The Pluto Case and the Nature of Science

NASA Astrophysics Data System (ADS)

Nóbrega de Albuquerque, Vanessa; Leite, Cristina

2016-08-01

Pluto had its classification changed in 2006, from planet to “dwarf planet”. This change had great impact in the media. Pluto returned to the news due to the arrival of New Horizons probe to Pluto in July 2015. Whereas the understanding of the complexity involved in the definition of celestial bodies could help us to show science as a historic, social, collective, non-linear and non-neutral process, it is presented a historical survey of the episodes involving the various definitions for planet, since the first observations of the sky made by our ancestors until the resolutions that defined which are the attributes of a "planet " made at the 26th General Assembly of the International Astronomical Union, meeting at which it was decided to reclassify Pluto. In order contribute to help perform discussions about the nature of science involving Astronomy themes, it is explained which features of scientific knowledge become evident during the study of the mentioned episodes.

Pluto: Planet or "Dwarf Planet"?

NASA Astrophysics Data System (ADS)

Voelzke, M. R.; de Araújo, M. S. T.

2010-09-01

In August 2006 during the XXVI General Assembly of the International Astronomical Union (IAU), taken place in Prague, Czech Republic, new parameters to define a planet were established. According to this new definition Pluto will be no more the ninth planet of the Solar System but it will be changed to be a "dwarf planet". This reclassification of Pluto by the academic community clearly illustrates how dynamic science is and how knowledge of different areas can be changed and evolves through the time, allowing to perceive Science as a human construction in a constant transformation, subject to political, social and historical contexts. These epistemological characteristics of Science and, in this case, of Astronomy, constitute important elements to be discussed in the lessons, so that this work contributes to enable Science and Physics teachers who perform a basic education to be always up to date on this important astronomical fact and, thereby, carry useful information to their teaching.

Newest Member of Our Solar System Artist Concept

NASA Image and Video Library

2005-08-03

This artist concept shows the planet catalogued as 2003UB313 at the lonely outer fringes of our solar system. Our Sun can be seen in the distance. The new planet is at least as big as Pluto and about three times farther away from the Sun than Pluto.

Pluto-Charon: Infrared Reflectance from 3.6 to 8.0 Micrometers

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.; Emery, Joshua P.; Stansberry, John A.; VanCleve, Jeffrey E.

2004-01-01

We have measured the spectral reflectance of the Pluto-Charon pair at 3.6, 4.5, 5.8, and 8.0 micrometers with the Infrared Array Camera (IRAC) (G. G. Fazzio et al. Ap.J.Supp. 154, 10-17, 2004) on the Spitzer Space Telescope (STS), at eight different longitudes that cover a full rotation of the planet. STS does not have sufficient resolution to separate the light from the planet and the satellite. The image of the Pluto-Charon pair is clearly visible at each of the four wavelengths. We will discuss the spectral reflectance in terms of models that include the known components of Pluto and Charon s surfaces, and evidence for diurnal variations.

Pluto Express: Mission to Pluto

NASA Technical Reports Server (NTRS)

Giuliano, J. A.

1996-01-01

Pluto is the smallest, outermost and last-discovered planet in the Solar System and the only one that has never been visited by a spacecraft from Earth. Pluto and its relatively large satellite Charon are the destinations of a proposed spacecraft mission for the next decade, being developed for NASA by scientists and engineers at NASA's Jet Propulsion Laboratory.

"Pluto Has Been a Planet My Whole Life!" Emotions, Attitudes, and Conceptual Change in Elementary Students' Learning about Pluto's Reclassification

ERIC Educational Resources Information Center

Broughton, Suzanne H.; Sinatra, Gale M.; Nussbaum, E. Michael

2013-01-01

Learning about certain scientific topics has potential to spark strong emotions among students. We investigated whether emotions predicted students' attitudes after engaging in independent rereading and/or rereading plus discussion about Pluto's reclassification. Fifth and sixth grade students read a refutation text on Pluto's reclassification.…

Exploring the Trans-Neptunian Solar System

NASA Astrophysics Data System (ADS)

1998-01-01

A profound question for scientists, philosophers and, indeed, all humans concerns how the solar system originated and subsequently evolved. To understand the solar system's formation, it is necessary to document fully the chemical and physical makeup of its components today, particularly those parts thought to retain clues about primordial conditions and processes.] In the past decade, our knowledge of the outermost, or trans-neptunian, region of the solar system has been transformed as a result of Earth-based observations of the Pluto-Charon system, Voyager 2's encounter with Neptune and its satellite Triton, and recent discoveries of dozens of bodies near to or beyond the orbit of Neptune. As a class, these newly detected objects, along with Pluto, Charon, and Triton, occupy the inner region of a hitherto unexplored component of the solar system, the Kuiper Belt. The Kuiper Belt is believed to be a reservoir of primordial objects of the type that formed in the solar nebula and eventually accreted to form the major planets. The Kuiper Belt is also thought to be the source of short-period comets and a population of icy bodies, the Centaurs, with orbits among the giant planets. Additional components of the distant outer solar system, such as dust and the Oort comet cloud, as well as the planet Neptune itself, are not discussed in this report. Our increasing knowledge of the trans-neptunian solar system has been matched by a corresponding increase in our capabilities for remote and in situ observation of these distant regions. Over the next 10 to 15 years, a new generation of ground- and space-based instruments, including the Keck and Gemini telescopes and the Space Infrared Telescope Facility, will greatly expand our ability to search for and conduct physical and chemical studies on these distant bodies. Over the same time span, a new generation of lightweight spacecraft should become available and enable the first missions designed specifically to explore the icy bodies that orbit 30 astronomical units (AU) or more from the Sun. The combination of new knowledge, plus the technological capability to greatly expand this knowledge over the next decade or so, makes this a particularly opportune time to review current understanding of the trans-neptunian solar system and to begin planning for the future exploration of this distant realm. Based on current knowledge, studies of trans-neptunian objects are important for a variety of reasons that can be summarized under five themes: (1) Exploration of new territory; (2) reservoirs of primitive materials; (3) Processes that reveal the solar system's origin and evolution; (4) Links to extrasolar planets; and (5) prebiotic chemistry. These five themes are not on an equal footing. The first three are well-established areas of scientific investigation and are backed up by a substantial body of observational and theoretical understanding. The last two, however are more speculative. They are included here because they raise a number of interesting possibilities that seem particularly suited to an interdisciplinary approach uniting planetary scientists with their colleagues in the astrophysical and life science communities. Although not considered in any detail in this report, the distant outer solar system also has direct relevance to Earth and the other terrestrial planets because it is the source of comets that bring volatiles into the inner solar system. The resulting inevitable impacts between comets and other planetary bodies can play major roles in the evolution of life as suggested by, for example, the Cretaceous-tertiary boundary bolide and the extinction of the dinosaurs.

Sedna Orbit Animation

NASA Technical Reports Server (NTRS)

2004-01-01

This animation shows the location of the newly discovered planet-like object, dubbed 'Sedna,' in relation to the rest of the solar system. Starting at the inner solar system, which includes the orbits of Mercury, Venus, Earth, and Mars (all in yellow), the view pulls away through the asteroid belt and the orbits of the outer planets beyond (green). Pluto and the distant Kuiper Belt objects are seen next until finally Sedna comes into view. As the field widens the full orbit of Sedna can be seen along with its current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. Moving past Sedna, what was previously thought to be the inner edge of the Oort cloud appears. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

Sedna Size Comparisons Artist Concept

NASA Image and Video Library

2004-03-15

The artist's rendition shows the newly discovered planet-like object, dubbed "Sedna," in relation to other bodies in the solar system, including Earth and its Moon; Pluto; and Quaoar, a planetoid beyond Pluto that was until now the largest known object beyond Pluto. The diameter of Sedna is slightly smaller than Pluto's but likely somewhat larger than Quaoar. http://photojournal.jpl.nasa.gov/catalog/PIA05567

Our Solar System Features Eight Planets

NASA Technical Reports Server (NTRS)

2009-01-01

Our solar system features eight planets, seen in this artist's diagram. Although there is some debate within the science community as to whether Pluto should be classified as a Planet or a dwarf planet, the International Astronomical Union has decided on the term plutoid as a name for dwarf planets like Pluto.

This representation is intentionally fanciful, as the planets are depicted far closer together than they really are. Similarly, the bodies' relative sizes are inaccurate. This is done for the purpose of being able to depict the solar system and still represent the bodies with some detail. (Otherwise the Sun would be a mere speck, and the planets even the majestic Jupiter would be far too small to be seen.)

Miniatue Propulsion Components for the Pluto Fast Flyby Spacecraft

NASA Technical Reports Server (NTRS)

Morash, D. H.; Strand, L.

1994-01-01

Pluto is the only planet in our solar system not yet visited by our spacecraft. Recent observations through the Hubble Space Telescope have given us a glimpse of Pluto and it's moon Charon, but their small size and immense distance from earth have preserved their mystery.

X-Rays from Pluto

NASA Image and Video Library

2016-09-14

The first detection of Pluto in X-rays has been made using NASA's Chandra X-ray Observatory in conjunction with observations from NASA's New Horizons spacecraft. As New Horizons approached Pluto in late 2014 and then flew by the planet during the summer of 2015, Chandra obtained data during four separate observations. During each observation, Chandra detected low-energy X-rays from the small planet. The main panel in this graphic is an optical image taken from New Horizons on its approach to Pluto, while the inset shows an image of Pluto in X-rays from Chandra. There is a significant difference in scale between the optical and X-ray images. New Horizons made a close flyby of Pluto but Chandra is located near the Earth, so the level of detail visible in the two images is very different. The Chandra image is 180,000 miles across at the distance of Pluto, but the planet is only 1,500 miles across. Pluto is detected in the X-ray image as a point source, showing the sharpest level of detail available for Chandra or any other X-ray observatory. This means that details over scales that are smaller than the X-ray source cannot be seen here. Detecting X-rays from Pluto is a somewhat surprising result given that Pluto - a cold, rocky world without a magnetic field - has no natural mechanism for emitting X-rays. However, scientists knew from previous observations of comets that the interaction between the gases surrounding such planetary bodies and the solar wind - the constant streams of charged particles from the sun that speed throughout the solar system -- can create X-rays. The researchers were particularly interested in learning more about the interaction between the gases in Pluto's atmosphere and the solar wind. The New Horizon spacecraft carries an instrument designed to measure that activity up-close -- Solar Wind Around Pluto (SWAP) -- and scientists examined that data and proposed that Pluto contains a very mild, close-in bowshock, where the solar wind first "meets" Pluto (similar to a shock wave that forms ahead of a supersonic aircraft) and a small wake or tail behind the planet. The immediate mystery is that Chandra's readings on the brightness of the X-rays are much higher than expected from the solar wind interacting with Pluto's atmosphere. The Chandra detection is also surprising since New Horizons discovered Pluto's atmosphere was much more stable than the rapidly escaping, "comet-like" atmosphere that many scientists expected before the spacecraft flew past in July 2015. In fact, New Horizons found that Pluto's interaction with the solar wind is much more like the interaction of the solar wind with Mars, than with a comet. While Pluto is releasing enough gas from its atmosphere to make the observed X-rays, there isn't enough solar wind flowing directly at Pluto at its great distance from the Sun to make them according to certain theoretical models. There are several suggested possibilities for the enhanced X-ray emission from Pluto. These include a much wider and longer tail of gases trailing Pluto than New Horizons detected using its SWAP instrument. Because Pluto is so small compared to the size of a Chandra point source, scientists may be unable to detect such a tail in X-rays. Other possibilities are that interplanetary magnetic fields are focusing more particles than expected from the solar wind into the region around Pluto, or the low density of the solar wind in the outer solar system at the distance of Pluto could allow for the formation of a doughnut, or torus, of neutral gas centered around Pluto's orbit. It will take deeper and higher resolution images of X-rays from Pluto's environment than we currently have from Chandra to distinguish between these possibilities. http://photojournal.jpl.nasa.gov/catalog/PIA21061

The Pluto Affair: The good, the bad or the ugly?

NASA Astrophysics Data System (ADS)

Lindberg Christensen, Lars

2007-08-01

The International Astronomical Union (IAU) General Assembly in Prague 2006 was the setting of one of the most discussed stories of 2006 - the much hated and loved IAU Resolution to define a planet. The Resolution changed Pluto's status to a dwarf planet and resulted in an unprecedented emotional discussion. The author will start the discussion with some first-hand impressions of the events with the perspective of the IAU Press Officer. The discussion can then address other impressions of what happened in Prague. What were the negative and positive outcomes of the Pluto Affair? What can we learn from this experience?

Magnitudes of selected stellar occultation candidates for Pluto and other planets, with new predictions for Mars and Jupiter

NASA Technical Reports Server (NTRS)

Sybert, C. B.; Bosh, A. S.; Sauter, L. M.; Elliot, J. L.; Wasserman, L. H.

1992-01-01

Occultation predictions for the planets Mars and Jupiter are presented along with BVRI magnitudes of 45 occultation candidates for Mars, Jupiter, Saturn, Uranus, and Pluto. Observers can use these magnitudes to plan observations of occultation events. The optical depth of the Jovian ring can be probed by a nearly central occultation on 1992 July 8. Mars occults an unusually red star in early 1993, and the occultations for Pluto involving the brightest candidates would possibly occur in the spring of 1992 and the fall of 1993.

Pluto.

ERIC Educational Resources Information Center

Binzel, Richard P.

1990-01-01

Discussed are details of what is known about the composition, physical characteristics, and formation of the planet Pluto and its satellite, Charon. Alignments of these bodies and details of their rotations and revolutions are described. (CW)

Research in planetary astronomy and operation of the Mauna Kea Observatory

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.

1988-01-01

Spectroscopic studies with ground-based telescopes at low resolution can give compositional information of the surfaces and atmospheres of planets, satellites, asteroids, and comets. Solid state absorptions in ices and minerals are measurable by the low-resolution spectrophotometric technique. This program includes spectroscopy of distant comets, asteroids of particular interest in various contexts (planet crossers, outer main belt, trojans, etc.), Pluto and Charon, and planetary satellites of particular interest (Iapetus, Io, Uranian satellites, etc.). In the case of planets, satellites, and comets, emphasis is placed on volatiles (ices and organics), while for asteroids the stress is on mineralogy and the connection with the meteorites. New spectra show that the IR signature of Triton has changed since 1980, in that the methane bands are significantly weaker. Spectral evidence for the presence of molecular nitrogen remains convincing. Also, the brightness of Triton throughout its orbital cycle was measured to higher precision than before and was found to be constant to better than 0.02 mag. Suggestive spectral evidence was found for the presence of the C-H stretching mode band in diffuse reflection on asteroid 130 Elektra.

Double Planet Meets Triple Star

NASA Astrophysics Data System (ADS)

2002-08-01

High-Resolution VLT Image of Pluto Event on July 20, 2002 A rare celestial phenomenon involving the distant planet Pluto has occurred twice within the past month. Seen from the Earth, this planet moved in front of two different stars on July 20 and August 21, respectively, providing observers at various observatories in South America and in the Pacific area with a long awaited and most welcome opportunity to learn more about the tenuous atmosphere of that cold planet. On the first date, a series of very sharp images of a small sky field with Pluto and the star was obtained with the NAOS-CONICA (NACO) adaptive optics (AO) camera mounted on the ESO VLT 8.2-m YEPUN telescope at the Paranal Observatory. With a diameter of about 2300 km, Pluto is about six times smaller than the Earth. Like our own planet, it possesses a relatively large moon, Charon , measuring 1200 km across and circling Pluto at a distance of about 19,600 km once every 6.4 days. In fact, because of the similarity of the two bodies, the Pluto-Charon system is often referred to as a double planet . At the current distance of nearly 4,500 million km from the Earth, Pluto's disk subtends a very small angle in the sky, 0.107 arcsec. It is therefore very seldom that Pluto - during its orbital motion - passes exactly in front of a comparatively bright star. Such events are known as "occultations" , and it is difficult to predict exactly when and where on the Earth's surface they are visible. Stellar occultations When Pluto moves in front of a star, it casts a "shadow" on the Earth's surface within which an observer cannot see the star, much like the Earth's Moon hides the Sun during a total solar eclipse. During the occultation event, Pluto's "shadow" also moves across the Earth's surface. The width of this shadow is equal to Pluto's diameter, i.e. about 2300 km. One such occultation event was observed in 1988, and two others were expected to occur in 2002, according to predictions published in 2000 by American astronomers Steve W. McDonald and James L. Elliot (Massachussetts Institute of Technology [MIT], Cambridge, USA). Further refinements provided by other observers later showed that the first event would be visible from South America on July 20, 2002 , while a second one on August 21 was expected to be observable in the Pacific basin, from the western coast of North America down to Hawaii and New Zealand. A stellar occultation provides a useful opportunity to study the planetary atmosphere, by means of accurate photometric measurements of the dimming of the stellar light, as the planet moves in front of the star. The observed variation of the light intensity and colour provides crucial information about the structure (atmospheric layers) and composition of different gases and aerosols. More information is available in the Appendix below. The July 20 occultation ESO PR Photo 21a/02 ESO PR Photo 21a/02 [Preview - JPEG: 400 x 477 pix - 65k] [Normal - JPEG: 800 x 953 pix - 224k] Caption : PR Photo 21c/02 shows the path of Pluto's shadow (grey region) during the July 20, 2002 occultation. The shadow has a diameter of about 2300 km and moves from right to left; the timings along the central line are indicated in one-minute intervals (Universal Time - UT). The width of the gray area corresponds to the regions where more than 50% of the light from the star P126 A was attenuated by Pluto's atmosphere. The dotted lines indicate where the stellar flux was attenuated by more than 10%. The maximum duration of the occultation (for observers located at the middle of the shadow track) was about 3 min. The plot is based on astrometric measurements posted at the MIT site. Once completely analyzed, the VLT NACO images will provide significantly better accuracy on the location of this track and therefore a solid basis for the interpretation of the photometric observations obtained with other telescopes. In order to profit from the rare opportunity to learn more about Pluto and its atmosphere, a large campaign involving more than twenty scientists and engineers from the Paris Observatory and associated institutions [1] was organized to observe the July 20, 2002, event involving an occultation of a star of visual magnitude 11 (i.e., about 100 times fainter than what can be perceived with then unaided eye), referred to as "P126" in McDonald and Elliot's catalogue. In May 2002, preparatory observations showed that star to be double, with the brighter component of the system ( "P126 A" ) being likely to be occulted by Pluto, as seen from South America. However, because of the duplicity, the predictions of exactly where the shadow of Pluto would sweep the ground were uncertain by about 0.1 arcsec in the sky, corresponding to more than 2000 km on the ground. The NACO images ESO PR Photo 21b/02 ESO PR Photo 21b/02 [Preview - JPEG: 400 x 469 pix - 47k] [Normal - JPEG: 800 x 937 pix - 208k] ESO PR Photo 21c/02 ESO PR Photo 21c/02 [Preview - JPEG: 400 x 467 pix - 53k] [Normal - JPEG: 800 x 933 pix - 232k] Caption : PR Photo 21b/02 shows one of the images obtained with the NAOS-CONICA (NACO) adaptive optics (AO) camera mounted on the ESO VLT 8.2-m YEPUN telescope at the Paranal Observatory in connection with a stellar occultation by Pluto on July 20, 2002. The star was found to be triple - the three components (A, B and C), as well as Pluto and its moon, Charon, are indicated in PR Photo 21c/02 for easy orientation. The images are based on data available from the NACO data webpage. See the text for details. In the end, the close approach (an "appulse" in astronomical terminology) of Pluto and P126 A was indeed observed from various sites in South America, with several mobile telescopes and also including major facilities at the ESO La Silla and Paranal Observatories. In particular, unique and very sharp images were obtained with the NAOS-CONICA (NACO) adaptive optics (AO) camera mounted on the ESO VLT 8.2-m YEPUN telescope . One of the NACO images is shown in PR Photos 21b-c/02 . These images were made during the final adjustments of the NACO instrument and in anticipation of the upcoming science verification observations. All frames are now publicly available from the NACO data webpage on the ESO site. The NACO image shown was obtained in infrared light (in the K-band at wavelength 2.2 µm) on July 20, 2002, some 45 min before Pluto's shadow passed north of Paranal ( Photo 21a/02) . The orientation is such that North is up, and East is left. The small sky field measures about 7 x 7 arcsec 2. The pixel size is 0.027 arcsec, and the achieved image sharpness corresponds to the theoretical limit (the diffraction limit) with a telescope of this size and at this wavelength (0.07 arcsec). The object at the centre is the star P126 A of K-magnitude 9.5 (see also Photo 21c/02 where the objects are identified), while the brighter object at the right is the companion star P126 B , 2.25 arcsec away. As P126 B is very red (of stellar type M), it appears brighter than P126 A at this infrared wavelength - the opposite is true in visible light. The intensity of the left part of the image has been multiplied by a factor of approximately 35 in order to better display Pluto and its moon Charon , located some 0.5 arcsec to the lower left (SE) of the planet. Note also the faint star "P126 C" , at this moment very close to Pluto; it is probably a (physical) member of the P126 system. A closer inspection of the original image shows that the disk of Pluto (with a diameter of 0.107 arscec and covering 16 NACO pixels) is (barely) resolved. Many images were taken by NACO prior to the occultation. They will allow to retrace the precise motion of Pluto relative to P126 A, thereby improving the mapping of the motion of Pluto's shadow on the ground, cf. Photo 21a/02 . This is important in order to apply the correct geometrical circumstances for the interpretation of the photometric observations. A first evaluation of the NACO data indicates that the Paranal site "missed" the upper layers of Pluto's atmosphere by a mere 200 km or so - this is equivalent to no more than one hundredth of an arcsec as projected on the sky. More information A full report on the NACO observations and other results by the present group of astronomers, also from the subsequent occultation of another star on August 21, 2002, that was extensively observed with the Canada-France-Hawaii Telescope (CFHT) on Mauna Kea (Hawaii, USA), is available at this URL: http://despa.obspm.fr/~sicardy/pluton/results.html Other sharp NACO images have been published recently, e.g. ESO PR 25/01 , ESO PR Photos 04a-c/02 and ESO PR Photos 19a-c/02. Note [1]: The group from the Observatoire de Paris and other observatories is lead by Bruno Sicardy and also includes François Colas, Thomas Widemann, Françoise Roques, Christian Veillet, Jean-Charles Cuillandre, Wolfgang Beisker, Cyril Birnbaum, Kate Brooks, Audrey Delsanti, Pierre Drossart, Agnès Fienga, Eric Gendron, Mike Kretlow, Anne-Marie Lagrange, Jean Lecacheux, Emmanuel Lellouch, Cédric Leyrat, Alain Maury, Elisabeth Raynaud, Michel Rapaport, Stefan Renner and Mathias Schultheis . From ESO participated Nancy Ageorges, Olivier Hainaut, Chris Lidman and Jason Spyromilio . Contact Bruno Sicardy LESIA - Observatoire de Paris France Phone: +33-1-45 07 71 15 email: bruno.sicardy@obspm.fr Appendix: Stellar occultations and Pluto's atmosphere Stellar occultations are presently the only way to probe Pluto's tenuous atmosphere . When the star moves behind the planet, the stellar rays suffer minute deviations as they are refracted (i.e., bent and defocussed) by the planet's atmospheric layers. This effect, together with the large distance to the planet, manifests itself as a gradual decline of observed intensity of the stellar light, rather than an abrupt drop as this would be the case if the planet had no atmosphere. Pluto's atmosphere was first detected on August 19, 1985, during a stellar occultation observed from Israel and then studied in more detail from Australia and from the Kuiper Airborne Observatory (KAO) during another such event on July 9, 1988. However, Pluto's atmosphere is still not well understood. It appears to be mostly composed of a dominant gas of atomic weight 28, probably molecular nitrogen (N 2 ). Near-IR solar reflection spectra have since shown a small presence of methane (CH 4 ), probably at a level of about 1% relative to nitrogen. The 1988 occultation clearly revealed two different layers in Pluto's atmosphere, a rather smooth and isothermal outer part, and a more complex one near the planet's surface, with the possible presence of an inversion layer (in which the temperature increases with altitude) or possibly haze of photochemical origin. The present observations aimed at discriminating between the current theoretical models of Pluto's atmosphere by means of detailed measurements of the changing intensity and colour of the stellar light, as the star is seen through progressively lower layers of the planet's atmosphere. Another important issue is the question of whether Pluto's atmosphere has changed since 1988. In the intervening 14 years, the planet has moved away from the Sun in its elliptic orbit, whereby there has been a change in the insolation (solar flux) of about 6%. This effect might possibly have caused changes in the surface temperature and in the overall atmospheric structure of Pluto. However, any firm conclusions will have to await a complete and careful evaluation of all available observations. ESO PR Photos 21a-c/02 may be reproduced, if credit is given to the European Southern Observatory (ESO).

The Extraordinary Albedo Variations on Pluto Detected by New Horizons and Implications for Dwarf Planet Eris

NASA Astrophysics Data System (ADS)

Buratti, Bonnie J.; Hofgartner, Jason D.; Stern, S. Alan; Weaver, Harold A.; Verbiscer, Anne J.; Ennico, Kimberly; Olkin, Catherine B.; Young, Leslie; New Horizons Geology and Geophysics Team

2016-10-01

The New Horizons mission returned stunning observations of active geology on the surface of Pluto (Stern et al., 2015, Science 350, 292). One of the markers for activity on planets or moons is normal albedos approaching 1.0, as is the case for Enceladus (Buratti et al., 1984, Icarus 58, 254; Verbiscer et al., 2005, Icarus 173, 66). When all corrections for viewing geometry are made for Pluto, it has normal albedos that approach unity in the regions that show evidence for activity by a lack of craters, notably the region informally named Sputnik Planum. On the other hand, Pluto also has a very dark (normal albedo ~0.10) equatorial belt.The geometric albedo of Eris, another large dwarf planet in the Kuiper Belt, is 0.96 (Sicardy et al., 2011, Nature 478, 493), close to that of Enceladus. Coupled with a high density of 2.5 gm/cc (Sicardy et al., ibid.), implying an even larger amount of radiogenic heating than that for Pluto (with a density near 1.9 gm/cc), we find it highly likely that Eris is also active with some type of solid state convection or cryovolcanism on its surface. Alternate explanations such as complete condensation of methane frost onto its surface in the colder environment at nearly 100 AUs would not lead to the high albedo observed.Another implication of the extreme albedo variations on Pluto is that the temperature varies by at least 20K on its surface, spawning possible aeolian processes and associated features such as wind streaks and dunes, which are currently being sought on New Horizons images. Finally, low albedo regions on Pluto, with normal reflectances less than 0.10, provide possible evidence for dust in the Kuiper Belt that is accreting onto the surface of Pluto. Another - or additional - explanation for this low-albedo dust is native material created in Pluto's hazy atmosphere.New Horizons funding by NASA is gratefully acknowledged.

The Pluto Affair: When Professionals talk to Professionals with the Public Watching

NASA Astrophysics Data System (ADS)

Lindberg Christensen, Lars

This paper gives a first-hand look behind the scenes of the Press Room at the International Astronomical Union (IAU) XXVIth General Assembly in Prague that was the setting of one of the most discussed stories in 2006 - the much hated and loved International Astronomical Union resolution defining a planet. The vote passing the resolution that - as a side-effect - changed Pluto's status to a "dwarf planet" and resulted in an unprecedented emotional argument about our Solar System. What actually happened in Prague? What were the negative and positive outcomes of the Pluto Affair? What can science communicators learn from this experience?

NASA's Evolving Views of Pluto

NASA Image and Video Library

2015-07-15

NASA's New Horizons spacecraft flew within 8,000 miles of dwarf planet Pluto on 14 July 2015. Our view of this cold, previously unexplored world, 4.67 billion miles from Earth, has evolved since its discovery by Clyde W. Tombaugh in 1930. This short clip shows images from Tombaugh, Hubble and New Horizons over the years, arranged to illustrate improvements in resolution. The close-up image at the end of this clip was taken about 1.5 hours before New Horizons closest approach to Pluto, when the craft was 47,800 miles (77,000 kilometers) from the surface of the planet. The image easily resolves structures smaller than a mile across. Credit: NASA/Goddard

Image Analysis of the 2012 Pluto (Near) Occultation

DTIC Science & Technology

2013-09-01

Image Analysis of the 2012 Pluto (Near) Occultation Keith T. Knox Air Force Research Laboratory ABSTRACT Imagery was gathered at the AMOS...observatory on the 3.6-meter telescope for the expected occultation of a star by the dwarf planet, Pluto , on 29 June 2012. The imagery was taken at...5 Hz for 40 minutes before and after the expected time of occultation. The initial analysis of the photometry indicated that Pluto did not occult

KSC-05pd2528

NASA Image and Video Library

2005-11-29

KENNEDY SPACE CENTER, FLA. - In the Vertical Integration Facility on Launch Complex 41 at Cape Canaveral Air Force Station in Florida, workers maneuver the fifth and final solid rocket booster into place for mating to the Lockheed Martin Atlas V rocket. Two of the other four rockets are seen at left. The Atlas V is the launch vehicle for the Pluto-bound New Horizons spacecraft that will make the first reconnaissance of Pluto and its moon, Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. As it approaches Pluto, the spacecraft will look for ultraviolet emission from Pluto's atmosphere and make the best global maps of Pluto and Charon in green, blue, red and a special wavelength that is sensitive to methane frost on the surface. It will also take spectral maps in the near infrared, telling the science team about Pluto's and Charon’s surface compositions and locations and temperatures of these materials. When the spacecraft is closest to Pluto or its moon, it will take close-up pictures in both visible and near-infrared wavelengths. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and Charon in July 2015.

Reorientation and faulting of Pluto due to volatile loading within Sputnik Planitia.

PubMed

Keane, James T; Matsuyama, Isamu; Kamata, Shunichi; Steckloff, Jordan K

2016-12-01

Pluto is an astoundingly diverse, geologically dynamic world. The dominant feature is Sputnik Planitia-a tear-drop-shaped topographic depression approximately 1,000 kilometres in diameter possibly representing an ancient impact basin. The interior of Sputnik Planitia is characterized by a smooth, craterless plain three to four kilometres beneath the surrounding rugged uplands, and represents the surface of a massive unit of actively convecting volatile ices (N 2 , CH 4 and CO) several kilometres thick. This large feature is very near the Pluto-Charon tidal axis. Here we report that the location of Sputnik Planitia is the natural consequence of the sequestration of volatile ices within the basin and the resulting reorientation (true polar wander) of Pluto. Loading of volatile ices within a basin the size of Sputnik Planitia can substantially alter Pluto's inertia tensor, resulting in a reorientation of the dwarf planet of around 60 degrees with respect to the rotational and tidal axes. The combination of this reorientation, loading and global expansion due to the freezing of a possible subsurface ocean generates stresses within the planet's lithosphere, resulting in a global network of extensional faults that closely replicate the observed fault networks on Pluto. Sputnik Planitia probably formed northwest of its present location, and was loaded with volatiles over million-year timescales as a result of volatile transport cycles on Pluto. Pluto's past, present and future orientation is controlled by feedbacks between volatile sublimation and condensation, changing insolation conditions and Pluto's interior structure.

KSC-05pd2312

NASA Image and Video Library

2005-10-07

KENNEDY SPACE CENTER, FLA. - At NASA Kennedy Space Center’s Payload Hazardous Servicing Facility, a technician from the Applied Physics Laboratory works on the New Horizons spacecraft before installing one of the panels. A series of interconnecting panels will enclose the spacecraft beneath the antenna to maintain safe operating temperatures in space. New Horizons will make the first reconnaissance of Pluto and its moon, Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. As it approaches Pluto, the spacecraft will look for ultraviolet emission from Pluto's atmosphere and make the best global maps of Pluto and Charon in green, blue, red and a special wavelength that is sensitive to methane frost on the surface. It will also take spectral maps in the near infrared, telling the science team about Pluto's and Charon's surface compositions and locations and temperatures of these materials. When the spacecraft is closest to Pluto or its moon, it will take close-up pictures in both visible and near-infrared wavelengths. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and Charon in July 2015.

KSC-05pd2311

NASA Image and Video Library

2005-10-07

KENNEDY SPACE CENTER, FLA. - At NASA Kennedy Space Center’s Payload Hazardous Servicing Facility, technicians from the Applied Physics Laboratory work on a panel they are installing on the New Horizons spacecraft. A series of interconnecting panels will enclose the spacecraft beneath the antenna to maintain safe operating temperatures in space. New Horizons will make the first reconnaissance of Pluto and its moon, Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. As it approaches Pluto, the spacecraft will look for ultraviolet emission from Pluto's atmosphere and make the best global maps of Pluto and Charon in green, blue, red and a special wavelength that is sensitive to methane frost on the surface. It will also take spectral maps in the near infrared, telling the science team about Pluto's and Charon's surface compositions and locations and temperatures of these materials. When the spacecraft is closest to Pluto or its moon, it will take close-up pictures in both visible and near-infrared wavelengths. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and Charon in July 2015.

KSC-05pd2314

NASA Image and Video Library

2005-10-07

KENNEDY SPACE CENTER, FLA. - At NASA Kennedy Space Center’s Payload Hazardous Servicing Facility, technicians from the Applied Physics Laboratory install another panel on the New Horizons spacecraft. A series of interconnecting panels will enclose the spacecraft beneath the antenna to maintain safe operating temperatures in space. New Horizons will make the first reconnaissance of Pluto and its moon, Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. As it approaches Pluto, the spacecraft will look for ultraviolet emission from Pluto's atmosphere and make the best global maps of Pluto and Charon in green, blue, red and a special wavelength that is sensitive to methane frost on the surface. It will also take spectral maps in the near infrared, telling the science team about Pluto's and Charon's surface compositions and locations and temperatures of these materials. When the spacecraft is closest to Pluto or its moon, it will take close-up pictures in both visible and near-infrared wavelengths. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and Charon in July 2015.

KSC-05pd2315

NASA Image and Video Library

2005-10-07

KENNEDY SPACE CENTER, FLA. - At NASA Kennedy Space Center’s Payload Hazardous Servicing Facility, technicians from the Applied Physics Laboratory install another panel on the New Horizons spacecraft. A series of interconnecting panels will enclose the spacecraft beneath the antenna to maintain safe operating temperatures in space. New Horizons will make the first reconnaissance of Pluto and its moon, Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. As it approaches Pluto, the spacecraft will look for ultraviolet emission from Pluto's atmosphere and make the best global maps of Pluto and Charon in green, blue, red and a special wavelength that is sensitive to methane frost on the surface. It will also take spectral maps in the near infrared, telling the science team about Pluto's and Charon's surface compositions and locations and temperatures of these materials. When the spacecraft is closest to Pluto or its moon, it will take close-up pictures in both visible and near-infrared wavelengths. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and Charon in July 2015.

KSC-05pd2313

NASA Image and Video Library

2005-10-07

KENNEDY SPACE CENTER, FLA. - At NASA Kennedy Space Center’s Payload Hazardous Servicing Facility, technicians work on a panel they are installing on the New Horizons spacecraft. A series of interconnecting panels will enclose the spacecraft beneath the antenna to maintain safe operating temperatures in space. New Horizons will make the first reconnaissance of Pluto and its moon, Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. As it approaches Pluto, the spacecraft will look for ultraviolet emission from Pluto's atmosphere and make the best global maps of Pluto and Charon in green, blue, red and a special wavelength that is sensitive to methane frost on the surface. It will also take spectral maps in the near infrared, telling the science team about Pluto's and Charon's surface compositions and locations and temperatures of these materials. When the spacecraft is closest to Pluto or its moon, it will take close-up pictures in both visible and near-infrared wavelengths. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and Charon in July 2015.

KSC-05pd2323

NASA Image and Video Library

2005-10-11

KENNEDY SPACE CENTER, FLA. - Inside the mobile service tower on Launch Complex 41 at Cape Canaveral Air Force Station in Florida, workers oversee the lowering of the Lockheed Martin Atlas V Centaur stage (above) toward the first stage. The two stages will be mated. The Atlas V is the launch vehicle for the New Horizons spacecraft. New Horizons will make the first reconnaissance of Pluto and its moon, Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. As it approaches Pluto, the spacecraft will look for ultraviolet emission from Pluto's atmosphere and make the best global maps of Pluto and Charon in green, blue, red and a special wavelength that is sensitive to methane frost on the surface. It will also take spectral maps in the near infrared, telling the science team about Pluto's and Charon's surface compositions and locations and temperatures of these materials. When the spacecraft is closest to Pluto or its moon, it will take close-up pictures in both visible and near-infrared wavelengths. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and Charon in July 2015.

A Neptune Trojan Survey for the New Horizons Spacecraft

NASA Astrophysics Data System (ADS)

Sheppard, Scott

2010-06-01

Trojan asteroids share a planet's semi-major axis but lead (L4) or follow (L5) the planet by about 60 degrees near the two triangular Lagrangian points of equilibrium. These minor planets were likely captured in these locations around the planet formation epoch and thus their current dynamical and physical properties will help constrain the formation, evolution and migration of the planets. The Neptune Trojans currently consist of only six known objects, all in the leading L4 cloud. Three of these were discovered in our initial survey of the L4 region allowing us to determine that Neptune was likely on a much more eccentric orbit in the distant past. We propose to continue a survey for Neptune Trojans in the trailing L5 region and to recover promising candidates found in 2009A with Subaru. Only with knowledge of the Trojan numbers and orbits in both the L4 and L5 clouds will we be able to understand their formation and evolution and further constrain planet accretion and migration. In addition, the New Horizons spacecraft will pass through the Neptune L5 region in 2013 on its way to Pluto. It is important that we understand the possible dust production produced by collisions of the Trojans as well as find suitable Trojans that New Horizons will observe as it passes through the area.

A Colorful Landing on Pluto

NASA Image and Video Library

2017-01-21

What would it be like to actually land on Pluto? This image is one of more than 100 images taken by NASA's New Horizons spacecraft over six weeks of approach and close flyby in the summer of 2015. A video offers a trip down onto the surface of Pluto -- starting with a distant view of Pluto and its largest moon, Charon -- and leading up to an eventual ride in for a "landing" on the shoreline of Pluto's informally named Sputnik Planitia. After a 9.5-year voyage covering more than three billion miles, New Horizons flew through the Pluto system on July 14, 2015, coming within 7,800 miles (12,500 kilometers) of Pluto. Carrying powerful telescopic cameras that could spot features smaller than a football field, New Horizons sent back hundreds of images of Pluto and its moons that show how dynamic and fascinating their surfaces are. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA11709

Pluto Express - Out of the Darkness

NASA Technical Reports Server (NTRS)

Herman, M.

1995-01-01

Pluto, discovered in 1930, is the largest of a class of primordial bodies at the edge of our solar system that have comet-like properties and remain relatively unmodified by warming from the sun. It is the only planet in the solar system not explored via robotic spacecraft. This lecture discusses the status of the Pluto Express preproject (science objectives, etc.), and its telecommunication subsystem.

NASA's Discovery Program: Moving Toward the Edge (of the Solar System)

NASA Technical Reports Server (NTRS)

Johnson, Les; Gilbert, Paul

2007-01-01

NASA's Planetary Science , Division sponsors a competitive program of small spacecraft missions with the goal of performing focused science investigations that complement NASA's larger planetary science explorations at relatively low cost. The goal of the Discovery program is to launch many smaller missions with fast development times to increase our understanding of the solar system by exploring the planets, dwarf planets, their moons, and small bodies such as comets and asteroids. Discovery missions are solicited from the broad planetary science community approximately every 2 years. Active missions within the Discovery program include several with direct scientific or engineering connections to potential future missions to the edge of the solar system and beyond. In addition to those in the Discovery program are the missions of the New Frontiers program. The first New Frontiers mission. is the New Horizons mission to Pluto, which will explore this 38-AU distant dwarf planet and potentially some Kuiper Belt objects beyond. The Discovery program's Dawn mission, when launched in mid-2007, will use ion drive as its primary propulsion system. Ion propulsion is one of only two technologies that appear feasible for early interstellar precursor missions with practical flight times. The Kepler mission will explore the structure and diversity of extrasolar planetary systems, with an emphasis on the detection of Earth-size planets around other stars. Kepler will survey nearby solar systems searching for planets that may fall within the habitable zone,' a region surrounding a star within which liquid water may exist on a planet's surface - an essential ingredient for life as we know it. With its open and competitive approach to mission selections, the Discovery program affords scientists the opportunity to propose missions to virtually any solar system destination. With its emphasis on science and proven openness to the use of new technologies such as ion propulsion, missions flown as part of the program will test out technologies needed for future very deep-space exploration and potentially take us to these difficult and distant destinations.

Two Faces of Pluto July 1

NASA Image and Video Library

2015-12-31

Pluto shows two remarkably different sides in these color images of the planet and its largest moon, Charon, taken by NASA New Horizons on June 25 and June 27, 2015. http://photojournal.jpl.nasa.gov/catalog/PIA20292

New Horizons Sees Pluto (Sept. 24) Note: There is debate within the science community as to whether

NASA Technical Reports Server (NTRS)

2007-01-01

A white arrow marks Pluto in this New Horizons Long Range Reconnaissance Imager (LORRI) picture taken Sept. 21, 2006. Seen at a distance of about 4.2 billion kilometers (2.6 billion miles) from the spacecraft, Pluto is little more than a faint point of light among a dense field of stars. Mission scientists knew they had Pluto in their sights when LORRI detected an unresolved 'point' in Pluto's predicted position, moving at the planet's expected motion across the constellation of Sagittarius near the plane of the Milky Way galaxy.

New Horizons Sees Pluto (Sept. 21) Note: There is debate within the science community as to whether

NASA Technical Reports Server (NTRS)

2007-01-01

A white arrow marks Pluto in this New Horizons Long Range Reconnaissance Imager (LORRI) picture taken Sept. 21, 2006. Seen at a distance of about 4.2 billion kilometers (2.6 billion miles) from the spacecraft, Pluto is little more than a faint point of light among a dense field of stars. Mission scientists knew they had Pluto in their sights when LORRI detected an unresolved 'point' in Pluto's predicted position, moving at the planet's expected motion across the constellation of Sagittarius near the plane of the Milky Way galaxy.

THE ROTATION PERIOD AND LIGHT-CURVE AMPLITUDE OF KUIPER BELT DWARF PLANET 136472 MAKEMAKE (2005 FY9)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heinze, A. N.; DeLahunta, Daniel

Kuiper Belt dwarf planet 136472 Makemake, formerly known as 2005 FY9, is currently the third-largest known object in the Kuiper Belt, after the dwarf planets Pluto and Eris. It is currently second only to Pluto in apparent brightness, due to Eris' much larger heliocentric distance. Makemake shows very little photometric variability, which has prevented confident determination of its rotation period until now. Using extremely precise time-series photometry, we find that the rotation period of Makemake is 7.7710 {+-} 0.0030 hr, where the uncertainty is a 90% confidence interval. An alias period is detected at 11.41 hr, but is determined withmore » approximately 95% confidence not to be the true period. Makemake's 7.77 hr rotation period is in the typical range for Kuiper Belt objects, consistent with Makemake's apparent lack of a substantial satellite to alter its rotation through tides. The amplitude of Makemake's photometric light curve is 0.0286 {+-} 0.0016 mag in V. This amplitude is about 10 times less than Pluto's, which is surprising given the two objects' similar sizes and spectral characteristics. Makemake's photometric variability is instead similar to that of Eris, which is so small that no confident rotation period has yet been determined. It has been suggested that dwarf planets such as Makemake and Eris, both farther from the Sun and colder than Pluto, exhibit lower photometric variability because they are covered with a uniform layer of frost. Such a frost is probably the correct explanation for Eris. However, it may be inconsistent with the spectrum of Makemake, which resembles reddish Pluto more than neutrally colored Eris. Makemake may instead be a more Pluto-like object that we observe at present with a nearly pole-on viewing geometry-a possibility that can be tested with continuing observations over the coming decades.« less

The Icy Cold Heart of Pluto

NASA Astrophysics Data System (ADS)

Hamilton, Douglas P.

2015-11-01

The locations of large deposits of frozen volatiles on planetary surfaces are largely coincident with areas receiving the minimum annual influx of solar energy; familiar examples include the polar caps of Earth and Mars. For planets tilted by more than 45 degrees, however, the poles actually receive more energy than some other latitudes. Pluto, with its current obliquity of 119 degrees, has minima in its average annual insolation at +/- 27 degrees latitude, with ~1.5% more energy flux going to the equator and ~15% more to the poles. Remarkably, the fraction of annual solar energy incident on different latitudes depends only on the obliquity of the planet and not on any of its orbital parameters.Over millions of years, Pluto's obliquity varies sinusoidally from 102-126 degrees, significantly affecting the latitudinal profile of solar energy deposition. Roughly 1Myr ago, the poles received 15% more energy that today while the equator received 13% less. The energy flux to latitudes between 25-35 degrees is far more stable, remaining low over the presumably billions of years since Pluto acquired its current spin properties. Like the poles at Earth, these mid latitudes on Pluto should be favored for the long-term deposition of volatile ices. This is, indeed, the location of the bright icy heart of Pluto, Sputnik Planum.Reflected light and emitted thermal radiation from Charon increases annual insolation to one side of Pluto by of order 0.02%. Although small, the bulk of the energy is delivered at night to Pluto's cold equatorial regions. Furthermore, Charon's thermal infrared radiation is easily absorbed by icy deposits on Pluto, slowing deposition and facilitating sublimation of volatiles. We argue that the slight but persistent preference for ices to form and survive in the anti-Charon Pluto's heart.

KSC-05pd2523

NASA Image and Video Library

2005-11-29

KENNEDY SPACE CENTER, FLA. - Viewed from high in the Vertical Integration Facility on Launch Complex 41 at Cape Canaveral Air Force Station in Florida, the fifth and final solid rocket booster is ready to be raised to vertical and lifted into the facility. It will be added to the other four already mated to the Lockheed Martin Atlas V rocket in the facility. The Atlas V is the launch vehicle for the Pluto-bound New Horizons spacecraft that will make the first reconnaissance of Pluto and its moon, Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. As it approaches Pluto, the spacecraft will look for ultraviolet emission from Pluto's atmosphere and make the best global maps of Pluto and Charon in green, blue, red and a special wavelength that is sensitive to methane frost on the surface. It will also take spectral maps in the near infrared, telling the science team about Pluto's and Charon’s surface compositions and locations and temperatures of these materials. When the spacecraft is closest to Pluto or its moon, it will take close-up pictures in both visible and near-infrared wavelengths. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and Charon in July 2015.

Highly integrated Pluto payload system (HIPPS): a sciencecraft instrument for the Pluto mission

NASA Astrophysics Data System (ADS)

Stern, S. Alan; Slater, David C.; Gibson, William; Reitsema, Harold J.; Delamere, W. Alan; Jennings, Donald E.; Reuter, D. C.; Clarke, John T.; Porco, Carolyn C.; Shoemaker, Eugene M.; Spencer, John R.

1995-09-01

We describe the design concept for the highly integrated Pluto payload system (HIPPS): a highly integrated, low-cost, light-weight, low-power instrument payload designed to fly aboard the proposed NASA Pluto flyby spacecraft destined for the Pluto/Charon system. The HIPPS payload is designed to accomplish all of the Pluto flyby prime (IA) science objectives, except radio science, set forth by NASA's Outer Planets Science Working Group (OPSWG) and the Pluto Express Science Definition Team (SDT). HIPPS contains a complement of three instrument components within one common infrastructure; these are: (1) a visible/near UV CCD imaging camera; (2) an infrared spectrograph; and (3) an ultraviolet spectrograph. A detailed description of each instrument is presented along with how they will meet the IA science requirements.

Pluto and Charon: A Case of Precession-Orbit Resonance?

NASA Technical Reports Server (NTRS)

Rubincam, David Parry; Smith, David E. (Technical Monitor)

2000-01-01

Pluto may be the only known case of precession-orbit resonance in the solar system. The Pluto-Charon system orbits the Sun with a period of 1 Plutonian year, which is 250.8 Earth years. The observed parameters of the system are such that Charon may cause Pluto to precess with a period near 250.8 Earth years. This gives rise to two possible resonances, heretofore unrecognized. The first is due to Pluto's orbit being highly eccentric, giving solar torques on Charon with a period of 1 Plutonian year. Charon in turn drives Pluto near its precession period. Volatiles, which are expected to shuttle across Pluto's surface between equator and pole as Pluto's obliquity oscillates, might change the planet's dynamical flattening enough so that Pluto crosses the nearby resonance, forcing the planet's equatorial plane to depart from Charon's orbital plane. The mutual tilt can reach as much as 2 deg after integrating over 5.6 x 10(exp 6) years, depending upon how close Pluto is to the resonance and the supply of volatiles. The second resonance is due to the Sun's traveling above and below Charon's orbital plane; it has a period half that of the eccentricity resonance. Reaching this half-Plutonian year resonance requires a much larger but still theoretically possible amount of volatiles. In this case the departure of Charon from an equatorial orbit is about 1 deg after integrating for 5.6 x 10(exp 6) years. The calculations ignore libration and tidal friction. It is not presently known how large the mutual tilt can grow over the age of the solar system, but if it remains only a few degrees, then observing such small angles from a Pluto flyby mission would be difficult. It is not clear why the parameters of the Pluto-Charon system are so close to the eccentricity resonance.

Plutonian Moon confirmed

NASA Astrophysics Data System (ADS)

In late February, two separate observations confirmed the 1978 discovery by U.S. Naval Observatory scientist James W. Christy of a moon orbiting the planet Pluto. According to the U.S. Naval Observatory, these two observations were needed before the International Astronomical Society (IAS) would officially recognize the discovery.Two types of observations of the moon, which was named Charon after the ferryman in Greek mythology who carried the dead to Pluto's realm, were needed for confirmation: a transit, in which the moon passes in front of Pluto, and an occultation, in which the moon passes behind the planet. These two phenomena occur only during an 8-year period every 124 years that had been calculated to take place during 1984-1985. Both events were observed in late February.

The removal of Pluto from the class of planets and homosexuality from the class of psychiatric disorders: a comparison.

PubMed

Zachar, Peter; Kendler, Kenneth S

2012-01-13

We compare astronomers' removal of Pluto from the listing of planets and psychiatrists' removal of homosexuality from the listing of mental disorders. Although the political maneuverings that emerged in both controversies are less than scientifically ideal, we argue that competition for "scientific authority" among competing groups is a normal part of scientific progress. In both cases, a complicated relationship between abstract constructs and evidence made the classification problem thorny.

The removal of pluto from the class of planets and homosexuality from the class of psychiatric disorders: a comparison

PubMed Central

2012-01-01

We compare astronomers' removal of Pluto from the listing of planets and psychiatrists' removal of homosexuality from the listing of mental disorders. Although the political maneuverings that emerged in both controversies are less than scientifically ideal, we argue that competition for "scientific authority" among competing groups is a normal part of scientific progress. In both cases, a complicated relationship between abstract constructs and evidence made the classification problem thorny. PMID:22244039

And Then There Were Nine

NASA Astrophysics Data System (ADS)

Benningfield, Damond

2005-03-01

Most people now take for granted that our solar system is home to nine planets orbiting as far away as 4.6 billion miles from the Sun. But in the late 1920s, the ninth planet, then known only as "Planet X" had yet to be discovered. Percival Lowell, a member of a rich Boston family and founder of Lowell Observatory in Arizona, calculated Planet X's likely position in the solar system by the gravitational effect it was having on the orbit of the eighth planet Neptune. But it was the diligence and hard work of a Kansas farm boy with little formal astronomy training, who was employed by Lowell Observatory, that finally produced the photographic evidence of a ninth planet. Clyde W. Tombaugh, who learned astronomy by building his own telescopes, found definitive evidence of Planet X in February 1930. The mystery planet was later named Pluto for the ancient god of the underworld. But the symbol for Pluto, an interlocking P and L, was made as a tribute to the man who had inspired the search for the ninth planet, Percival Lowell.

The Icy Mountains of Pluto

NASA Image and Video Library

2015-07-15

New close-up images of a region near Pluto's equator reveal a giant surprise: a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body. The mountains likely formed no more than 100 million years ago -- mere youngsters relative to the 4.56-billion-year age of the solar system -- and may still be in the process of building. That suggests the close-up region, which covers less than one percent of Pluto's surface, may still be geologically active today. The youthful age estimate is based on the lack of craters in this scene. Like the rest of Pluto, this region would presumably have been pummeled by space debris for billions of years and would have once been heavily cratered -- unless recent activity had given the region a facelift, erasing those pockmarks. Unlike the icy moons of giant planets, Pluto cannot be heated by gravitational interactions with a much larger planetary body. Some other process must be generating the mountainous landscape. The mountains are probably composed of Pluto's water-ice "bedrock." Although methane and nitrogen ice covers much of the surface of Pluto, these materials are not strong enough to build the mountains. Instead, a stiffer material, most likely water-ice, created the peaks. The close-up image was taken about 1.5 hours before New Horizons closest approach to Pluto, when the craft was 47,800 miles (770,000 kilometers) from the surface of the planet. The image easily resolves structures smaller than a mile across. http://photojournal.jpl.nasa.gov/catalog/PIA19710

Astrometrical observations of Pluto-Charon system with the automated telescopes of Pulkovo observatory

NASA Astrophysics Data System (ADS)

Slesarenko, V. Yu.; Bashakova, E. A.; Devyatkin, A. V.

2016-03-01

The space probe "New Horizons" was launched on 19th of January 2006 in order to study Pluto and its moons. Spacecraft performed close fly-by to Pluto on 14th of July 2015 and obtained the most detailed images of Pluto and its moon until this moment. At the same time, observation obtained by the ground-based telescopes may also be helpful for the research of such distant system. Thereby, the Laboratory of observational astrometry of Pulkovo Observatory of RAS made a decision to reprocess observations obtained during last decade. More than 350 positional observations of Pluto-Charon system were carried out with the mirror astrograph ZA-320M at Pulkovo and Maksutov telescope MTM-500M near Kislovodsk. These observations were processed by means of software system APEX-II developed in Pulkovo observatory and numerical simulations were performed to calculate the differences between positions of photocenter and barycenter of Pluto-Charon system.

The impactor flux in the Pluto-Charon system

NASA Technical Reports Server (NTRS)

Weissman, Paul R.; Stern, S. Alan

1994-01-01

Current impact rates of comets on Pluto and Charon are estimated. It is shown that the dominant sources of impactors are comets from the Kuiper belt and the inner Oort cloud, each of whose perihelion distribution extends across Pluto's orbit. In contrast, long-period comets from the outer Oort cloud are a negligible source of impactors. The total predicted number of craters is not sufficient to saturate the surface areas of either Pluto of Charon over the age of the Solar System. However, heavy cratering may have occurred early in the Solar System's history during clearing of planetesimals from the outer planets' zone.

CVF spectrophotometry of Pluto - Correlation of composition with albedo. [circularly variable filter

NASA Technical Reports Server (NTRS)

Marcialis, Robert L.; Lebofsky, Larry A.

1991-01-01

The present time-resolved, 0.96-2.65-micron spectrophotometry for the Pluto-Charon system indicates night-to-night variations in the depths of the methane absorptions such that the bands' equivalent width is near minimum light. The interpretation of these data in terms of a depletion of methane in dark regions of the planet, relative to bright ones, is consistent with the Buie and Fink (1987) observations. The near-IR spectrum of Pluto seems to be dominated by surface frost. It is suggested that the dark equatorial regions of Pluto are redder than those of moderate albedo.

Methods & Strategies: Poor, Poor Pluto

ERIC Educational Resources Information Center

Graham, Lori; West, Courtney; Jones, Lindsay

2013-01-01

Just as students never stop learning, neither do librarians and teachers. Learning is a process that is facilitated by interest and applicability. Therefore, it is imperative to develop instructional activities that students deem important and relevant. "Why is Pluto no longer a planet?" is a question whose answer many people, young and…

A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation.

PubMed

Sicardy, B; Ortiz, J L; Assafin, M; Jehin, E; Maury, A; Lellouch, E; Hutton, R Gil; Braga-Ribas, F; Colas, F; Hestroffer, D; Lecacheux, J; Roques, F; Santos-Sanz, P; Widemann, T; Morales, N; Duffard, R; Thirouin, A; Castro-Tirado, A J; Jelínek, M; Kubánek, P; Sota, A; Sánchez-Ramírez, R; Andrei, A H; Camargo, J I B; da Silva Neto, D N; Gomes, A Ramos; Martins, R Vieira; Gillon, M; Manfroid, J; Tozzi, G P; Harlingten, C; Saravia, S; Behrend, R; Mottola, S; Melendo, E García; Peris, V; Fabregat, J; Madiedo, J M; Cuesta, L; Eibe, M T; Ullán, A; Organero, F; Pastor, S; de Los Reyes, J A; Pedraz, S; Castro, A; de la Cueva, I; Muler, G; Steele, I A; Cebrián, M; Montañés-Rodríguez, P; Oscoz, A; Weaver, D; Jacques, C; Corradi, W J B; Santos, F P; Reis, W; Milone, A; Emilio, M; Gutiérrez, L; Vázquez, R; Hernández-Toledo, H

2011-10-26

The dwarf planet Eris is a trans-Neptunian object with an orbital eccentricity of 0.44, an inclination of 44 degrees and a surface composition very similar to that of Pluto. It resides at present at 95.7 astronomical units (1 AU is the Earth-Sun distance) from Earth, near its aphelion and more than three times farther than Pluto. Owing to this great distance, measuring its size or detecting a putative atmosphere is difficult. Here we report the observation of a multi-chord stellar occultation by Eris on 6 November 2010 UT. The event is consistent with a spherical shape for Eris, with radius 1,163 ± 6 kilometres, density 2.52 ± 0.05 grams per cm(3) and a high visible geometric albedo, Pv = 0.96(+0.09)(-0.04). No nitrogen, argon or methane atmospheres are detected with surface pressure larger than ∼1 nanobar, about 10,000 times more tenuous than Pluto's present atmosphere. As Pluto's radius is estimated to be between 1,150 and 1,200 kilometres, Eris appears as a Pluto twin, with a bright surface possibly caused by a collapsed atmosphere, owing to its cold environment. We anticipate that this atmosphere may periodically sublimate as Eris approaches its perihelion, at 37.8 astronomical units from the Sun.

Isotopic constraints on the source of Pluto's nitrogen and the history of atmospheric escape

NASA Astrophysics Data System (ADS)

Mandt, Kathleen E.; Mousis, Olivier; Luspay-Kuti, Adrienn

2016-10-01

The origin and evolution of nitrogen in solar system bodies is an important question for understanding processes that took place during the formation of the planets and solar system bodies. Pluto has an atmosphere that is 99% molecular nitrogen, but it is unclear if this nitrogen is primordial or derived from ammonia in the protosolar nebula. The nitrogen isotope ratio is an important tracer of the origin of nitrogen on solar system bodies, and can be used at Pluto to determine the origin of its nitrogen. After evaluating the potential impact of escape and photochemistry on Pluto's nitrogen isotope ratio (14N/15N), we find that if Pluto's nitrogen originated as N2 the current ratio in Pluto's atmosphere would be greater than 324 while it would be less than 157 if the source of Pluto's nitrogen were NH3. The New Horizons spacecraft successfully visited the Pluto system in July 2015 providing a potential opportunity to measure 14N/15N in N2.

Pluto and Charon in Color: Pluto-Centric View Animation

NASA Image and Video Library

2015-06-11

The first color movies from NASA's New Horizons mission show Pluto and its largest moon, Charon, and the complex orbital dance of the two bodies, known as a double planet. A near-true color movie were assembled from images made in three colors -- blue, red and near-infrared -- by the Multispectral Visible Imaging Camera on the instrument known as Ralph. The images were taken on nine different occasions from May 29-June 3, 2015. The movie is "Pluto-centric," meaning that Charon is shown as it moves in relation to Pluto, which is digitally centered in the movie. (The North Pole of Pluto is at the top.) Pluto makes one turn around its axis every 6 days, 9 hours and 17.6 minutes-the same amount of time that Charon rotates in its orbit. Looking closely at the images in this movie, one can detect a regular shift in Pluto's brightness-due to the brighter and darker terrains on its differing faces. http://photojournal.jpl.nasa.gov/catalog/PIA19689

The Pluto system: Initial results from its exploration by New Horizons.

PubMed

Stern, S A; Bagenal, F; Ennico, K; Gladstone, G R; Grundy, W M; McKinnon, W B; Moore, J M; Olkin, C B; Spencer, J R; Weaver, H A; Young, L A; Andert, T; Andrews, J; Banks, M; Bauer, B; Bauman, J; Barnouin, O S; Bedini, P; Beisser, K; Beyer, R A; Bhaskaran, S; Binzel, R P; Birath, E; Bird, M; Bogan, D J; Bowman, A; Bray, V J; Brozovic, M; Bryan, C; Buckley, M R; Buie, M W; Buratti, B J; Bushman, S S; Calloway, A; Carcich, B; Cheng, A F; Conard, S; Conrad, C A; Cook, J C; Cruikshank, D P; Custodio, O S; Dalle Ore, C M; Deboy, C; Dischner, Z J B; Dumont, P; Earle, A M; Elliott, H A; Ercol, J; Ernst, C M; Finley, T; Flanigan, S H; Fountain, G; Freeze, M J; Greathouse, T; Green, J L; Guo, Y; Hahn, M; Hamilton, D P; Hamilton, S A; Hanley, J; Harch, A; Hart, H M; Hersman, C B; Hill, A; Hill, M E; Hinson, D P; Holdridge, M E; Horanyi, M; Howard, A D; Howett, C J A; Jackman, C; Jacobson, R A; Jennings, D E; Kammer, J A; Kang, H K; Kaufmann, D E; Kollmann, P; Krimigis, S M; Kusnierkiewicz, D; Lauer, T R; Lee, J E; Lindstrom, K L; Linscott, I R; Lisse, C M; Lunsford, A W; Mallder, V A; Martin, N; McComas, D J; McNutt, R L; Mehoke, D; Mehoke, T; Melin, E D; Mutchler, M; Nelson, D; Nimmo, F; Nunez, J I; Ocampo, A; Owen, W M; Paetzold, M; Page, B; Parker, A H; Parker, J W; Pelletier, F; Peterson, J; Pinkine, N; Piquette, M; Porter, S B; Protopapa, S; Redfern, J; Reitsema, H J; Reuter, D C; Roberts, J H; Robbins, S J; Rogers, G; Rose, D; Runyon, K; Retherford, K D; Ryschkewitsch, M G; Schenk, P; Schindhelm, E; Sepan, B; Showalter, M R; Singer, K N; Soluri, M; Stanbridge, D; Steffl, A J; Strobel, D F; Stryk, T; Summers, M E; Szalay, J R; Tapley, M; Taylor, A; Taylor, H; Throop, H B; Tsang, C C C; Tyler, G L; Umurhan, O M; Verbiscer, A J; Versteeg, M H; Vincent, M; Webbert, R; Weidner, S; Weigle, G E; White, O L; Whittenburg, K; Williams, B G; Williams, K; Williams, S; Woods, W W; Zangari, A M; Zirnstein, E

2015-10-16

The Pluto system was recently explored by NASA's New Horizons spacecraft, making closest approach on 14 July 2015. Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto's atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto's diverse surface geology and long-term activity raise fundamental questions about how small planets remain active many billions of years after formation. Pluto's large moon Charon displays tectonics and evidence for a heterogeneous crustal composition; its north pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected. Copyright © 2015, American Association for the Advancement of Science.

Attività fotometrica di Plutone nel 2005

NASA Astrophysics Data System (ADS)

Bianciardi, Giorgio

2006-06-01

This report describes unfiltered CCD differential photometry of Pluto performed between 1 August and 10 September 2005. Results show that in the present year Pluto is maintaining a high photometric activity, higher than expected (maximum brightness variations of 0.29±0.02 magnitudes) in relation to the rotational period. Pluto's appearance is now drastically changing owing to viewing geometry and the next collapse of its atmosphere onto the surface. Amateurs too should dedicate particular attention to the photometric evolution of the planet.

The Other Red Planet Animation

NASA Image and Video Library

2015-07-03

What color is Pluto? The answer, revealed in the first maps made from New Horizons data, turns out to be shades of reddish brown. The mission's first map of Pluto is in approximate true color -- that is, the color you would see if you were riding on New Horizons. At left, a map of Pluto's northern hemisphere composed using high-resolution black-and-white images from New Horizons LORRI instrument. At right is a map of Pluto's colors created using data from the Ralph instrument. In the center is the combined map, produced by merging the LORRI and Ralph data. http://photojournal.jpl.nasa.gov/catalog/PIA19697

Probing Pluto's Atmosphere Using Ground-Based Stellar Occultations

NASA Astrophysics Data System (ADS)

Sicardy, Bruno; Rio de Janeiro Occultation Team, Granada Team, International Occultation and Timing Association, Royal Astronomical Society New Zealand Occultation Section, Lucky Star associated Teams

2016-10-01

Over the last three decades, some twenty stellar occultations by Pluto have been monitored from Earth. They occur when the dwarf planet blocks the light from a star for a few minutes as it moves on the sky. Such events led to the hint of a Pluto's atmosphere in 1985, that was fully confirmed during another occultation in 1988, but it was only in 2002 that a new occultation could be recorded. From then on, the dwarf planet started to move in front of the galactic center, which amplified by a large factor the number of events observable per year.Pluto occultations are essentially refractive events during which the stellar rays are bent by the tenuous atmosphere, causing a gradual dimming of the star. This provides the density, pressure and temperature profiles of the atmosphere from a few kilometers above the surface up to about 250 km altitude, corresponding respectively to pressure levels of about 10 and 0.1 μbar. Moreover, the extremely fine spatial resolution (a few km) obtained through this technique allows the detection of atmospheric gravity waves, and permits in principle the detection of hazes, if present.Several aspects make Pluto stellar occultations quite special: first, they are the only way to probe Pluto's atmosphere in detail, as the dwarf planet is far too small on the sky and the atmosphere is far too tenuous to be directly imaged from Earth. Second, they are an excellent example of participative science, as many amateurs have been able to record those events worldwide with valuable scientific returns, in collaboration with professional astronomers. Third, they reveal Pluto's climatic changes on decade-scales and constrain the various seasonal models currently explored.Finally, those observations are fully complementary to space exploration, in particular with the New Horizons (NH) mission. I will show how ground-based occultations helped to better calibrate some NH profiles, and conversely, how NH results provide some key boundary conditions necessary to analyze ground-based data.Part of the research leading to these results has received funding from the European Research Council under the European Community's H2020 (2014-2020/ ERC Grant Agreement n 669416 "LUCKY STAR").

Pluto followed its heart: reorientation and faulting of Pluto due to volatile loading in Sputnik Planum

NASA Astrophysics Data System (ADS)

Tuttle Keane, James; Matsuyama, Isamu; Kamata, Shunichi; Steckloff, Jordan

2016-10-01

The New Horizons flyby of Pluto revealed the dwarf planet to be a strikingly diverse, geologically active world. Perhaps the most intriguing feature on the New Horizons encounter hemisphere is Sputnik Planum—a 1000 km diameter, probable impact basin, filled with several kilometers of actively convecting volatile ices (N2, CH4, CO). One salient characteristic of Sputnik Planum is its curious alignment with the Pluto-Charon tidal axis. The alignment of large geologic features with principal axis of inertia (such as the tidal axis) is the hallmark of global reorientation, i.e. true polar wander. Here we show that the present location of Sputnik Planum is a natural consequence of loading of 1-2 km of volatile ices within the Sputnik Planum basin. Larger volatile ice thicknesses (like those inferred from studies of ice convection within Sputnik Planum) betray an underlying negative gravity anomaly associated with the basin. As Pluto reoriented in response to the loading of volatile ices within Sputnik Planum, stresses accumulated within the lithosphere (as each geographic location experiences a change in tidal/rotational potential). These reorientation stresses, coupled with loading stresses, and stresses from the freezing of a subsurface ocean resulted in the fracturing of Pluto's lithosphere in a characteristic, global pattern of extensional faults. Our predicted pattern of extensional faults due to this reorientation closely replicates the observed distribution of faults on Pluto (more so than global expansion, orbit migration, de-spinning, or loading alone). Sputnik Planum likely formed ~60° northwest of its present location, and was loaded with volatile ices over millions of years due to seasonal volatile transport cycles. This result places Pluto in a truly unique category of planetary bodies where volatiles are not only controlling surface geology and atmospheric processes, but they are also directly controlling the orientation of the entire dwarf planet. Pluto's past, present, and future orientation is controlled by complicated feedbacks between volatile transport, insolation, and interior structure.

The Cold and Icy Heart of Pluto

NASA Astrophysics Data System (ADS)

Hamilton, D. P.

2015-12-01

The locations of large deposits of frozen volatiles on planetary surfaces are largely coincident with areas receiving the minimum annual influx of solar energy. Thus we have the familiar polar caps of Earth and Mars, but cold equatorial regions for planets with obliquities between 54 and 126 degrees. Furthermore, for tilts between 45-66 degrees and 114-135 degrees the minimum incident energy occurs neither at the pole nor the equator. We find that the annual average insolation is always symmetric about Pluto's equator and is fully independent of the relative locations of the planet's pericenter and equinoxes. Remarkably, this symmetry holds for arbitrary orbital eccentricities and obliquities, and so we provide a short proof in the margin of this abstract. The current obliquity of Pluto is 119 degrees, giving it minima in average annual insolation at +/- 27 degrees latitude, with ~1.5% more flux to the equator and ~15% more to the poles. But the obliquity of Pluto also varies sinusoidally from 102-126 degrees and so, over the past million years, Pluto's annual equatorial and polar fluxes have changed by +15% and -13%, respectively. Interestingly, the energy flux received by latitudes between 25-35 degrees remains nearly constant over the presumably billions of years since Pluto acquired its current orbit and spin properties. Thus these latitudes are continuously cold and should be favored for the long-term deposition of volatile ices; the bright heart of Pluto, Sputnik Planum, extends not coincidentally across these latitudes. Reflected light and emitted thermal radiation from Charon increases annual insolation to one side of Pluto by of order 0.02%. Although small, the bulk of the energy is delivered at night to Pluto's cold equatorial regions. Furthermore, Charon's thermal IR is delivered very efficiently to icy deposits. Over billions of years, ices have preferentially formed and survived in the anti-Charon hemisphere.

Surface Compositions Across Pluto and Charon

NASA Technical Reports Server (NTRS)

Grundy, W. M.; Binzel, R. P.; Buratti, B. J.; Cook, J. C.; Cruikshank, D. P.; Dalle Ore, C. M.; Earle, A. M.; Ennico, K.; Howett, C. J. A.; Lunsford, A. W.;

The New Solar System

ERIC Educational Resources Information Center

Wilkinson, John

2009-01-01

Since 2006, the details of bodies making up our solar system have been revised. This was largely as a result of new discoveries of a number of planet-like objects beyond the orbit of Pluto. The International Astronomical Union redefined what constituted a planet and established two new classifications--dwarf planets and plutoids. As a result, the…

NASA Missions Have Their Eyes Peeled on Pluto Artist Concept

NASA Image and Video Library

2015-07-09

This artist concept shows NASA fleet of observatories busily gathering data before and after July 14, 2015 to help piece together what we know about Pluto, and what features New Horizons data might help explain. What's icy, has "wobbly" potato-shaped moons, and is arguably the world's favorite dwarf planet? The answer is Pluto, and NASA's New Horizons is speeding towards the edge of our solar system for a July 14 flyby. It won't be making observations alone; NASA's fleet of observatories will be busy gathering data before and after to help piece together what we know about Pluto, and what features New Horizons data might help explain. http://photojournal.jpl.nasa.gov/catalog/PIA19703

Mapping Pluto Methane Ice

NASA Image and Video Library

2015-09-24

The Ralph/LEISA infrared spectrometer on NASA's New Horizons spacecraft mapped compositions across Pluto's surface as it flew past the planet on July 14, 2015. On the left, a map of methane ice abundance shows striking regional differences, with stronger methane absorption indicated by the brighter purple colors, and lower abundances shown in black. Data have only been received so far for the left half of Pluto's disk. At right, the methane map is merged with higher-resolution images from the spacecraft's Long Range Reconnaissance Imager (LORRI). http://photojournal.jpl.nasa.gov/catalog/PIA19953

Imagine a Landing on Pluto

NASA Image and Video Library

2016-07-14

Imagine a future spacecraft following New Horizons' trailblazing path to Pluto, but instead of flying past its target -- as New Horizons needed to do to explore Pluto and the Kuiper Belt beyond -- the next visitor touches down near the tall mountains on the frozen icy, plains of Pluto's heart. A video produced by New Horizons scientists that offers that very perspective. Made from more than 100 New Horizons images taken over six weeks of approach and close flyby, the video offers a trip in to Pluto -- starting with a distant spacecraft's-eye view of Pluto and its largest moon, Charon, to an eventual ride in for a "landing" on the shoreline of Pluto's informally named Sputnik Planum. The video shows what it would be like to ride aboard an approaching spacecraft and see Pluto grow from a "dot" to become a world, and then to swoop down over Pluto's spectacular terrains. New Horizons scientists had to interpolate some of the frames in the movie based on what they know Pluto looks like to make it as smooth and seamless as possible. After a 9.5-year voyage covering more than three billion miles, New Horizons flew through the Pluto system on July 14, 2015, coming within 7,800 miles (12,500 kilometers) of Pluto itself. Carrying powerful telescopic cameras that could spot features smaller than a football field, New Horizons has sent back hundreds of images of Pluto and its moons that show how dynamic and fascinating their surfaces are - and what great targets they'd make for follow-up mission one day. http://photojournal.jpl.nasa.gov/catalog/PIA20742

Twelve-year planetary ephemeris: 1995-2006

NASA Technical Reports Server (NTRS)

Espenak, Fred

1994-01-01

Accurate geocentric positions and physical ephemerides are tabulated for the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto for the 12-year period 1995 through 2006. The frequency interval is 2 days for the Sun and classical planets. Uranus, Neptune, and Pluto are tabulated at 4-day intervals. Because of its rapid apparent motion, the Moon's ephemeris is given daily.

Spinning Moons

NASA Image and Video Library

2015-11-10

Most inner moons in the solar system keep one face pointed toward their central planet; this frame from an animation by NASA New Horizons shows that certainly isnt the case with the small moons of Pluto, which behave like spinning tops. Pluto is shown at center with, in order, from smaller to wider orbit: Charon, Styx, Nix, Kerberos, Hydra. http://photojournal.jpl.nasa.gov/catalog/PIA20152

The Pluto debate: Influence of emotions on belief, attitude, and knowledge change

NASA Astrophysics Data System (ADS)

Broughton, Suzanne H.

In line with the "warming trend" (Sinatra, 2005), this study examined the influence of emotions during controversial conceptual change. Issues in science may trigger highly emotional responses (e.g., evolutionary theory). However, it is unclear whether these emotions facilitate or inhibit change. I investigated the nature of emotions engendered when learning about a controversial science topic, Pluto's reclassification, including the valence (positive/negative) and activation (activating/deactivating) of emotions (Pekrun et al., 2002). I also investigated whether belief, attitude, and/or conceptual change could be facilitated through rereading a refutation text and/or rereading during small group discussions. Refutation texts directly state a common misconception, refute it, and provide the scientific explanation as a plausible alternative (Hynd, 2001). Participants were randomly assigned to a group (reread text; reread text plus small group discussions). Participants in both groups read the same refutational text regarding the recent change in the definition of planet and Pluto's reclassification. The findings show that students' experienced a range of emotions towards Pluto's reclassification. Students reported experiencing more negative than positive emotions. Both positive and negative emotions were shown to be predictive of student's attitudes and attitude change. Emotions were also predictive of students' knowledge of planets and conceptual change. This suggests that emotions may have promoted deep engagement and critical thinking. Negative emotions may also be linked with resistance to attitude and conceptual change. The refutation text was effective in promoting belief change, attitude change, and conceptual change across both conditions. Students in both conditions reported more constructivist nature of science beliefs after rereading the text. Students also reported a greater level of acceptance about Pluto's reclassification. Conceptual change was promoted through the text as students' initial misconceptions about why scientists rewrote the definition of planet. Students in the reread plus discussion group showed greater conceptual change regarding the reasons for rewriting the definition of planet than those in the reread group. This study supports the "warming trend" (Sinatra, 2005) in conceptual change research because it shows the interplay between emotions and the change process. The findings also suggest that belief, attitude, and conceptual change can be fostered through small group discussions.

Changes in Pluto's Atmosphere Revealed by Occultations

NASA Astrophysics Data System (ADS)

Sicardy, Bruno; Widemann, Thomas; Lellouch, Emmanuel; Veillet, Christian; Colas, Francois; Roques, Francoise; Beisker, Wolfgang; Kretlow, Mike; Cuillandre, Jean-Charles; Hainaut, Olivier

After the discovery and study of Pluto's tenuous atmosphere in 1985 and 1988 with stellar occultations 14 years were necessary before two other occultations by the planet could be observed on 20 July 2002 and 21 August 2002 from Northern Chile with a portable telescope and from CFHT in Hawaii respectively. These occultations reveal drastric changes in Pluto's nitrogen atmosphere whose pressure increased by a factor two or more since 1988. In spite of an increasing distance to the Sun (and a correlated decrease of solar energy input at Pluto) this increase can be explained by the fact that Pluto's south pole went from permanent darkness to permanent illumination between 1988 and 2002. This might cause the sublimation of the south polar cap and the increase of pressure which could go on till 2015 according to current nitrogen cycle models. Furthermore we detect temperature contrasts between the polar and the equatorial regions probed on Pluto possibly caused by different diurnally averaged insolations at those locations. Finally spikes observed in the light curves reveal a dynamical activity in Pluto's atmosphere.

Pluto and Charon in Color: Barycentric View Animation

NASA Image and Video Library

2015-06-11

The first color movies from NASA's New Horizons mission show Pluto and its largest moon, Charon, and the complex orbital dance of the two bodies, known as a double planet. A near-true color movie was assembled from images made in three colors -- blue, red and near-infrared -- by the Multispectral Visible Imaging Camera on the instrument known as Ralph. The images were taken on nine different occasions from May 29-June 3, 2015. The movie is barycentric, meaning that both Pluto and Charon are shown in motion around the binary's barycenter -- the shared center of gravity between the two bodies as they do a planetary jig. Because Pluto is much more massive than Charon, the barycenter (marked by a small "x" in the movie) is much closer to Pluto than to Charon. Looking closely at the images in this movie, one can detect a regular shift in Pluto's brightness-due to the brighter and darker terrains on its differing faces. http://photojournal.jpl.nasa.gov/catalog/PIA19688

Comparative mapping of Pluto's sub-Charon hemisphere - Three least squares models based on mutual event lightcurves

NASA Technical Reports Server (NTRS)

Young, Eliot F.; Binzel, Richard P.

1993-01-01

Observations of Charon transits are used here to derive preliminary maps of Pluto's sub-Charon hemisphere. Three models are used to describe the brightness of Pluto's surface as functions of latitude and longitude. Mapping results are presented using spherical harmonic functions, polynomial functions, and finite elements. A smoothing algorithm applied to the maps is described and the validity and resolution of the maps is tested by reconstruction from synthetic data. A preliminary finding from the maps is that the south polar region has the highest albedo of any location on the planet.

Pluto's Ultraviolet Airglow and Detection of Ions in the Upper Atmosphere

NASA Astrophysics Data System (ADS)

Steffl, A.; Young, L. A.; Kammer, J.; Gladstone, R.; Hinson, D. P.; Summers, M. E.; Strobel, D. F.; Stern, S. A.; Weaver, H. A., Jr.; Olkin, C.; Ennico Smith, K.

2017-12-01

In July 2015, the Alice ultraviolet spectrograph aboard the New Horizons spacecraft made numerous observations of Pluto and its atmosphere. We present here the far ultraviolet reflectance spectrum of Pluto and airglow emissions from its atmosphere. At wavelengths greater than 1400Å, Pluto's spectrum is dominated by sunlight reflected from the surface of the planet. Various hydrocarbon species such as C2H4 are detected in absorption of the solar continuum. Below 1400Å, Pluto's atmosphere is opaque and the surface cannot be detected. However, after carefully removing various sources of background light, we see extremely faint airglow emissions (<0.05 Rayleighs/Ångstrom) from Pluto's atmosphere. All of the emissions are produced by nitrogen in various forms: molecular, atomic, and singly ionized. The detection of N+ at 1086Å is the first, and thus far only, direct detection of ions in Pluto's atmosphere. This N+ emission line is produced primarily by dissociative photoionization of molecular N2 by solar EUV photons (energy > 34.7 eV; wavelength < 360Å). Notably absent from Pluto's spectrum are emission lines from argon at 1048 and 1067Å. We place upper limits on the amount of argon in Pluto's atmosphere above the tau=1 level (observed to be at 750km tangent altitude) that are significantly lower than pre-encounter atmospheric models.

The carbon budget in the outer solar nebula.

PubMed

Simonelli, D P; Pollack, J B; McKay, C P; Reynolds, R T; Summers, A L

1989-01-01

Detailed models of the internal structures of Pluto and Charon, assuming rock and water ice as the only constituents, indicate that the mean silicate mass fraction of this two-body system is on the order of 0.7; thus the Pluto/Charon system is significantly "rockier" than the satellites of the giant planets (silicate mass fraction approximately 0.55). This compositional contrast reflects different formation mechanisms: it is likely that Pluto and Charon formed directly from the solar nebula, while the circumplanetary nebulae that produced the giant planet satellites were derived from envelopes that surrounded the forming giant planets (envelopes in which icy planetesimals dissolved more readily than rocky planetesimals). Simple cosmic abundance calculations, and the assumption that the Pluto/Charon system formed directly from solar nebula condensates, strongly suggest that the majority of the carbon in the outer solar nebula was in the form of carbon monoxide; these results are consistent with (1) inheritance from the dense molecular clouds in the interstellar medium (where CH4/CO < 10(-2) in the gas phase) and/or (2) of the Lewis and Prinn kinetic inhibition model of solar nebula chemistry. Theoretical predictions of the C/H enhancements in the atmospheres of the giant planets, when compared to the actual observed enhancements, suggest that 10%, or slightly more, of the carbon in the outer solar nebula was in the form of condensed materials (although the amount of condensed C may have dropped slightly with increasing heliocentric distance). Strict compositional limits computed for the Pluto/Charon system using the densities of CH4 and CO ices indicate that these pure ices are at best minor components in the interiors of these bodies, and imply that CH4 and CO ices were not the dominant C-bearing solids in the outer nebula. Clathrate-hydrates could not have appropriated enough CH4 or CO to be the major form of condensed carbon, although such clathrates may be necessary to explain the presence of methane on Pluto after its formation from a CO-rich nebula. Laboratory studies of carbonaceous chondrites, and spacecraft observations of Comet Halley, strongly suggest that of the remaining possibilities, organic material, rather than elemental carbon, is the most likely candidate for the dominant C-bearing solid in the outer solar nebula. We conclude that the majority of the carbon in the outer solar nebula was in gaseous CO; 10% to a few tens of percent of the C was in condensed organic materials; and at least a trace amount of carbon was in methane gas.

Global albedos of Pluto and Charon from LORRI New Horizons observations

NASA Astrophysics Data System (ADS)

Buratti, B. J.; Hofgartner, J. D.; Hicks, M. D.; Weaver, H. A.; Stern, S. A.; Momary, T.; Mosher, J. A.; Beyer, R. A.; Verbiscer, A. J.; Zangari, A. M.; Young, L. A.; Lisse, C. M.; Singer, K.; Cheng, A.; Grundy, W.; Ennico, K.; Olkin, C. B.

2017-05-01

The exploration of the Pluto-Charon system by the New Horizons spacecraft represents the first opportunity to understand the distribution of albedo and other photometric properties of the surfaces of objects in the Solar System's ;Third Zone; of distant ice-rich bodies. Images of the entire illuminated surface of Pluto and Charon obtained by the Long Range Reconnaissance Imager (LORRI) camera provide a global map of Pluto that reveals surface albedo variegations larger than any other Solar System world except for Saturn's moon Iapetus. Normal reflectances on Pluto range from 0.08-1.0, and the low-albedo areas of Pluto are darker than any region of Charon. Charon exhibits a much blander surface with normal reflectances ranging from 0.20-0.73. Pluto's albedo features are well-correlated with geologic features, although some exogenous low-albedo dust may be responsible for features seen to the west of the area informally named Tombaugh Regio. The albedo patterns of both Pluto and Charon are latitudinally organized, with the exception of Tombaugh Regio, with darker regions concentrated at the Pluto's equator and Charon's northern pole. The phase curve of Pluto is similar to that of Triton, the large moon of Neptune believed to be a captured Kuiper Belt Object (KBO), while Charon's is similar to that of the Moon. Preliminary Bond albedos are 0.25 ± 0.03 for Charon and 0.72 ± 0.07 for Pluto. Maps of an approximation to the Bond albedo for both Pluto and Charon are presented for the first time. Our work shows a connection between very high albedo (near unity) and planetary activity, a result that suggests the KBO Eris may be currently active.

Planet X - Fact or fiction?

NASA Technical Reports Server (NTRS)

Anderson, John

1988-01-01

The search for a possible tenth planet in our solar system is examined. The history of the discoveries of Uranus, Neptune, and Pluto are reviewed. Searches of the sky with telescopes and theoretical studies of the gravitational influences on the orbits of known objects in the solar system are discussed. Information obtained during the Pioneer 10 and 11 missions which could suggest the presence of an undiscovered planet and computer simulations of the possible orbit of a tenth planet are presented.

Self-Stirring of Debris Discs by Planetesimals Formed by Pebble Concentration

NASA Astrophysics Data System (ADS)

Krivov, Alexander V.; Booth, Mark

2018-06-01

When a protoplanetary disc looses gas, it leaves behind planets and one or more planetesimal belts. The belts get dynamically excited, either by planets ("planet stirring") or by embedded big planetesimals ("self-stirring"). Collisions between planetesimals become destructive and start to produce dust, creating an observable debris disc. Following Kenyon & Bromley (2008), it is often assumed that self-stirring starts to operate as soon as the first ˜1000 km-sized embedded "Plutos" have formed. However, state-of-the-art pebble concentration models robustly predict planetesimals between a few km and ˜200 km in size to form in protoplanetary discs rapidly, before then slowly growing into Pluto-sized bodies. We show that the timescale, on which these planetesimals excite the disc sufficiently for fragmentation, is shorter than the formation timescale of Plutos. Using an analytic model based on the Ida & Makino (1993) theory, we find the excitation timescale to be T_excite ≈ 100 x_m^{-1} M_\\star ^{-3/2} a^3 Myr, where xm is the total mass of a protoplanetary disc progenitor in the units of the Minimum-Mass Solar Nebula, a its radius in the units of 100 AU, and M⋆ is the stellar mass in solar masses. These results are applied to a set of 23 debris discs that have been well resolved with ALMA or SMA. We find that the majority of these discs are consistent with being self-stirred. However, three large discs around young early-type stars do require planets as stirrers. These are 49 Cet, HD 95086, and HR 8799, of which the latter two are already known to have planets.

New Horizons Successful Completes the Historic First Flyby of Pluto and Its Moons

NASA Technical Reports Server (NTRS)

Ennico, Kimberly

2015-01-01

On July 14, 2015, after a 9.5 year trek across the solar system, NASA's New Horizons spacecraft flew by the dwarf planet Pluto and its system of moons, taking imagery, spectra and in-situ particle data. Data from New Horizons will address numerous outstanding questions on the geology and composition of Pluto and Charon, plus measurements of Pluto's atmosphere, and provide revised understanding of the formation and evolution of Pluto and Charon and its smaller moons. This data set is an invaluable glimpse into the outer Third Zone of the solar system. Data from the intense July 14th fly-by sequence will be downlinked to Earth over a period of 16 months, the duration set by the large data set (over 60 GBits) and the limited transmitted bandwidth rates (approx. 1-2 kbps) and sharing the three 70 m DSN assets with our missions. The small fraction (approx. 1%) of data downlinked during the early phase of the flyby has already revealed Pluto and Charon to be very different worlds, with increasing and dynamic complexity.

Outer Planet Exploration with Advanced Radioisotope Electric Propulsion

NASA Technical Reports Server (NTRS)

Oleson, Steven; Gefert, Leon; Patterson, Michael; Schreiber, Jeffrey; Benson, Scott; McAdams, Jim; Ostdiek, Paul

2002-01-01

In response to a request by the NASA Deep Space Exploration Technology Program, NASA Glenn Research Center conducted a study to identify advanced technology options to perform a Pluto/Kuiper mission without depending on a 2004 Jupiter Gravity Assist, but still arriving before 2020. A concept using a direct trajectory with small, sub-kilowatt ion thrusters and Stirling radioisotope power systems was shown to allow the same or smaller launch vehicle class as the chemical 2004 baseline and allow a launch slip and still flyby in the 2014 to 2020 timeframe. With this promising result the study was expanded to use a radioisotope power source for small electrically propelled orbiter spacecraft for outer planet targets such as Uranus, Neptune, and Pluto.

About the Linguistic Impossibility of Claiming that Small Planets are not Planets

NASA Astrophysics Data System (ADS)

Nedeljkovic, A. B.

2012-12-01

Philology, which is, the science of language and literature, must now offer assistance to the science of astronomy, about one question of terminology and logic. Namely, if something belongs to one category, then it is, regardless of its size (large, or medium, or small) a member of that category. Therefore, it was linguistically wrong to claim that Pluto is one of the dwarf planets and therefore not a planet. This mistake, much noticed by the world's public opinion, ought to be corrected immediately.

Pluto's Extended Atmosphere: New Horizons Alice Lyman-α Imaging

NASA Astrophysics Data System (ADS)

Retherford, Kurt D.; Gladstone, G. Randall; Stern, S. Alan; Weaver, Harold A.; Young, Leslie A.; Ennico, Kimberly A.; Olkin, Cathy B.; Cheng, Andy F.; Greathouse, Thomas K.; Hinson, David P.; Kammer, Joshua A.; Linscott, Ivan R.; Parker, Alex H.; Parker, Joel Wm.; Pryor, Wayne R.; Schindhelm, Eric; Singer, Kelsi N.; Steffl, Andrew J.; Strobel, Darrell F.; Summers, Michael E.; Tsang, Constantine C. C.; Tyler, G. Len; Versteeg, Maarten H.; Woods, William W.; Cunningham, Nathaniel J.; Curdt, Werner

2015-11-01

Pluto's upper atmosphere is expected to extend several planetary radii, proportionally more so than for any planet in our solar system. Atomic hydrogen is readily produced at lower altitudes due to photolysis of methane and transported upward to become an important constituent. The Interplanetary Medium (IPM) provides a natural light source with which to study Pluto's atomic hydrogen atmosphere. While direct solar Lyman-α emissions dominate the signal at 121.6 nm at classical solar system distances, the contribution of diffuse illumination by IPM Lyman-α sky-glow is roughly on par at Pluto (Gladstone et al., Icarus, 2015). Hydrogen atoms in Pluto's upper atmosphere scatter these bright Lyα emission lines, and detailed simulations of the radiative transfer for these photons indicate that Pluto would appear dark against the IPM Lyα background. The Pluto-Alice UV imaging spectrograph on New Horizons conducted several observations of Pluto during the encounter to search for airglow emissions, characterize its UV reflectance spectra, and to measure the radial distribution of IPM Lyα near the disk. Our early results suggest that these model predictions for the darkening of IPM Lyα with decreasing altitude being measureable by Pluto-Alice were correct. We'll report our progress toward extracting H and CH4 density profiles in Pluto's upper atmosphere through comparisons of these data with detailed radiative transfer modeling. These New Horizons findings will have important implications for determining the extent of Pluto's atmosphere and related constraints to high-altitude vertical temperature structure and atmospheric escape.This work was supported by NASA's New Horizons project.

Alice Solar Occultation

NASA Image and Video Library

2015-07-17

This figure shows how the Alice instrument count rate changed over time during the sunset and sunrise observations. The count rate is largest when the line of sight to the sun is outside of the atmosphere at the start and end times. Molecular nitrogen (N2) starts absorbing sunlight in the upper reaches of Pluto's atmosphere, decreasing as the spacecraft approaches the planet's shadow. As the occultation progresses, atmospheric methane and hydrocarbons can also absorb the sunlight and further decrease the count rate. When the spacecraft is totally in Pluto's shadow the count rate goes to zero. As the spacecraft emerges from Pluto's shadow into sunrise, the process is reversed. By plotting the observed count rate in the reverse time direction, it is seen that the atmospheres on opposite sides of Pluto are nearly identical. http://photojournal.jpl.nasa.gov/catalog/PIA19716

Mapping Pluto Broken Heart

NASA Image and Video Library

2015-10-29

In addition to transmitting new high-resolution images and other data on the familiar close-approach hemispheres of Pluto and Charon, NASA's New Horizons spacecraft is also returning images -- such as this one -- to improve maps of other regions. This image was taken by the New Horizons Long Range Reconnaissance Imager (LORRI) on the morning of July 13, 2015, from a range of 1.03 million miles (1.7 million kilometers) and has a resolution of 5.1 miles (8.3 kilometers) per pixel. It provides fascinating new details to help the science team map the informally named Krun Macula (the prominent dark spot at the bottom of the image) and the complex terrain east and northeast of Pluto's "heart" (Tombaugh Regio). Pluto's north pole is on the planet's disk at the 12 o'clock position of this image. http://photojournal.jpl.nasa.gov/catalog/PIA20037

A Close Look At Pluto

NASA Image and Video Library

2016-02-25

Pluto has long been a mystery, a dot at our solar system’s margins. The best images, even with NASA’s Hubble Space Telescope, were fuzzy and pixelated. In July 2015, NASA’s New Horizons spacecraft flew past Pluto and captured the sharpest views of the dwarf planet to date. One of the most striking areas, informally named "Sputnik Planum," is a sweeping, frozen plain the size of Texas and ringed by mountains of ice. Its smooth deposits are unmarred by impact craters, a stark contrast to the rest of Pluto’s battered surface. As a result, scientists believe the region formed recently, within the last few hundred million years. This contradicts past depictions of Pluto as an unchanging world. By analyzing images taken during the flyby, scientists hope to unravel more of the dwarf planet’s history. Watch the video for an up-close look at Pluto. Credit: NASA's Goddard Space Flight Center Video courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/S. Robbins

Configuration of Pluto's Volatile Ices

NASA Astrophysics Data System (ADS)

Grundy, William M.; Binzel, R. P.; Cook, J. C.; Cruikshank, D. P.; Dalle Ore, C. M.; Earle, A. M.; Ennico, K.; Jennings, D. E.; Howett, C. J. A.; Linscott, I. R.; Lunsford, A. W.; Olkin, C. B.; Parker, A. H.; Parker, J. Wm; Protopapa, S.; Reuter, D. C.; Singer, K. N.; Spencer, J. R.; Stern, S. A.; Tsang, C. C. C.; Verbiscer, A. J.; Weaver, H. A.; Young, L. A.; Berry, K.; Buie, M. W.; Stansberry, J. A.

2015-11-01

We report on near-infrared remote sensing by New Horizons' Ralph instrument (Reuter et al. 2008, Space Sci. Rev. 140, 129-154) of Pluto's N2, CO, and CH4 ices. These especially volatile ices are mobile even at Pluto's cryogenic surface temperatures. Sunlight reflected from these ices becomes imprinted with their characteristic spectral absorption bands. The detailed appearance of these absorption features depends on many aspects of local composition, thermodynamic state, and texture. Multiple-scattering radiative transfer models are used to retrieve quantitative information about these properties and to map how they vary across Pluto's surface. Using parameter maps derived from New Horizons observations, we investigate the striking regional differences in the abundances and scattering properties of Pluto's volatile ices. Comparing these spatial patterns with the underlying geology provides valuable constraints on processes actively modifying the planet's surface, over a variety of spatial scales ranging from global latitudinal patterns to more regional and local processes within and around the feature informally known as Sputnik Planum. This work was supported by the NASA New Horizons Project.

Revisiting the 1988 Pluto Occultation

NASA Astrophysics Data System (ADS)

Bosh, Amanda S.; Dunham, Edward W.; Young, Leslie A.; Slivan, Steve; Barba née Cordella, Linda L.; Millis, Robert L.; Wasserman, Lawrence H.; Nye, Ralph

2015-11-01

In 1988, Pluto's atmosphere was surmised to exist because of the surface ices that had been detected through spectroscopy, but it had not yet been directly detected in a definitive manner. The key to making such a detection was the stellar occultation method, used so successfully for the discovery of the Uranian rings in 1977 (Elliot et al. 1989; Millis et al. 1993) and before that for studies of the atmospheres of other planets.On 9 June 1988, Pluto occulted a star, with its shadow falling over the South Pacific Ocean region. One team of observers recorded this event from the Kuiper Airborne Observatory, while other teams captured the event from various locations in Australia and New Zealand. Preceding this event, extensive astrometric observations of Pluto and the star were collected in order to refine the prediction.We will recount the investigations that led up to this important Pluto occultation, discuss the unexpected atmospheric results, and compare the 1988 event to the recent 2015 event whose shadow followed a similar track through New Zealand and Australia.

Topographic Mapping of Pluto and Charon Using New Horizons Data

NASA Astrophysics Data System (ADS)

Schenk, P. M.; Beyer, R. A.; Moore, J. M.; Spencer, J. R.; McKinnon, W. B.; Howard, A. D.; White, O. M.; Umurhan, O. M.; Singer, K.; Stern, S. A.; Weaver, H. A.; Young, L. A.; Ennico Smith, K.; Olkin, C.; Horizons Geology, New; Geophysics Imaging Team

2016-06-01

New Horizons 2015 flyby of the Pluto system has resulted in high-resolution topographic maps of Pluto and Charon, the most distant objects so mapped. DEM's over ~30% of each object were produced at 100-300 m vertical and 300-800 m spatial resolutions, in hemispheric maps and high-resolution linear mosaics. Both objects reveal more relief than was observed at Triton. The dominant 800-km wide informally named Sputnik Planum bright ice deposit on Pluto lies in a broad depression 3 km deep, flanked by dispersed mountains 3-5 km high. Impact craters reveal a wide variety of preservation states from pristine to eroded, and long fractures are several km deep with throw of 0-2 km. Topography of this magnitude suggests the icy shell of Pluto is relatively cold and rigid. Charon has global relief of at least 10 km, including ridges of 2-3 km and troughs of 3-5 km of relief. Impact craters are up to 6 km deep. Vulcan Planum consists of rolling plains and forms a topographic moat along its edge, suggesting viscous flow.

The New Horizons Mission to Pluto and Flyby of Jupiter

NASA Technical Reports Server (NTRS)

Stern, Alan; Weaver, Hal; Young, Leslie; Bagenal, Fran; Binzel, Richard; Buratti, Bonnie; Cheng, andy; Cruikshank, Dale; Gladstone, Randy; Grundy, Will;

Triton: The Connection between Rosetta, New Horizons and a future Ice Giants Mission

NASA Astrophysics Data System (ADS)

Mandt, K.; Luspay-Kuti, A.; Mousis, O.

2017-12-01

Several planetary missions have made observations intended to evaluate the origin and evolution of volatiles in solar system atmospheres. This is an important topic that connects how planets, moons and small bodies formed to the question of past or present habitability. Comet isotope observations have been ongoing and have played a crucial role in this research. Measurements of the D/H in cometary water and 14N/15N in NH3, in particular, have been critical for evaluating the origin of water and nitrogen in the terrestrial planet atmospheres and for that of Saturn's moon Titan. We have conducted comparative studies modeling the escape, photochemistry and evolution of the atmospheres of Titan and Pluto to try to understand whether the nitrogen in these atmospheres originated as N2 or NH3 in the protosolar nebula. The origin of Titan's nitrogen has been well constrained, but uncertainties about isotope processes in Pluto's atmosphere leave the origin of Pluto's nitrogen difficult to resolve. Because of their similarities, Triton is subject to the same uncertainties and is of particular interest for understanding the origin of Triton's and Pluto's volatiles as well as of Kuiper Belt Objects in general. We will discuss how Rosetta, New Horizons and a future Ice Giants mission will each contribute to understanding the origin of nitrogen in these atmospheres and to the origin of volatiles in atmospheres throughout outer solar system.

The trans-neptunian object UB313 is larger than Pluto.

PubMed

Bertoldi, F; Altenhoff, W; Weiss, A; Menten, K M; Thum, C

2006-02-02

The most distant known object in the Solar System, 2003 UB313 (97 au from the Sun), was recently discovered near its aphelion. Its high eccentricity and inclination to the ecliptic plane, along with its perihelion near the orbit of Neptune, identify it as a member of the 'scattered disk'. This disk of bodies probably originates in the Kuiper belt objects, which orbit near the ecliptic plane in circular orbits between 30 and 50 au, and may include Pluto as a member. The optical brightness of 2003 UB313, if adjusted to Pluto's distance, is greater than that of Pluto, which suggested that it might be larger than Pluto. The actual size, however, could not be determined from the optical measurements because the surface reflectivity (albedo) was unknown. Here we report observations of the thermal emission of 2003 UB313 at a wavelength of 1.2 mm, which in combination with the measured optical brightness leads to a diameter of 3,000 +/- 300 +/- 100 km. Here the first error reflects measurement uncertainties, while the second derives from the unknown object orientation. This makes 2003 UB313 the largest known trans-neptunian object, even larger than Pluto (2,300 km). The albedo is 0.60 +/- 0.10 +/- 0.05, which is strikingly similar to that of Pluto, suggesting that the methane seen in the optical spectrum causes a highly reflective icy surface.

A New Planet in our Solar System? NASA Takes a Look

NASA Image and Video Library

2016-01-20

NASA’s Director of Planetary Science, Jim Green, discusses the Jan. 20, 2016 Astronomical Journal science paper that points to the possibility of a new “Planet 9” in our solar system beyond Pluto, examining the scientific process and inviting you to have a front row seat to our exploration of the solar system.

Do Other Planets Have Summer?

ERIC Educational Resources Information Center

Nelson, George

2005-01-01

It's important to keep two things in mind when thinking about the cause of the seasons: (1) Earth and all the other planets except Pluto and Mercury move around the Sun in almost perfect circles, getting neither closer nor farther away from the Sun during the year; and (2) Earth's rotation axis is tilted with respect to the plane of its orbit…

Pluto's Nonvolatile Chemical Compounds

NASA Astrophysics Data System (ADS)

Grundy, William M.; Binzel, Richard; Cook, Jason C.; Cruikshank, Dale P.; Dalle Ore, Cristina M.; Earle, Alissa M.; Ennico, Kimberly; Jennings, Donald; Howett, Carly; Kaiser, Ralf-Ingo; Linscott, Ivan; Lunsford, A. W.; Olkin, Catherine B.; Parker, Alex Harrison; Parker, Joel Wm.; Philippe, Sylvain; Protopapa, Silvia; Quirico, Eric; Reuter, D. C.; Schmitt, Bernard; Singer, Kelsi N.; Spencer, John R.; Stansberry, John A.; Stern, S. Alan; Tsang, Constantine; Verbiscer, Anne J.; Weaver, Harold A.; Weigle, G. E.; Young, Leslie

2016-10-01

Despite the migration of Pluto's volatile ices (N2, CO, and CH4) around the surface on seasonal timescales, the planet's non-volatile materials are not completely hidden from view. They occur in a variety of provinces formed over a wide range of timescales, including rugged mountains and chasms, the floors of mid-latitude craters, and an equatorial belt of especially dark and reddish material typified by the informally named Cthulhu Regio. NASA's New Horizons probe observed several of these regions at spatial resolutions as fine as 3 km/pixel with its LEISA imaging spectrometer, covering wavelengths from 1.25 to 2.5 microns. Various compounds that are much lighter than the tholin-like macromolecules responsible for the reddish coloration, but that are not volatile at Pluto surface temperatures such as methanol (CH3OH) and ethane (C2H6) have characteristic absorption bands within LEISA's wavelength range. This presentation will describe their geographic distributions and attempt to constrain their origins. Possibilities include an inheritance from Pluto's primordial composition (the likely source of H2O ice seen on Pluto's surface) or ongoing production from volatile precursors through photochemistry in Pluto's atmosphere or through radiolysis on Pluto's surface. New laboratory data inform the analysis.This work was supported by NASA's New Horizons project.

Three Views of Pluto

NASA Image and Video Library

2015-07-06

New Horizons' Long Range Reconnaissance Imager (LORRI) obtained these three images of Pluto between July 1-3 ,2015, as the spacecraft closed in on its July 14 encounter with the dwarf planet and its moons. The left image shows, on the right side of the disk, a large bright area on the hemisphere opposite Charon; this is the side of Pluto that will be seen in close-up by New Horizons on July 14. The three images together show the full extent of a continuous swath of dark terrain that wraps around Pluto's equatorial region between longitudes 40° and 160°. The western end of the swath, west of longitude 40°, breaks up into a series of striking dark regularly-spaced spots on the anti-Charon hemisphere (right image) that were first noted in New Horizons images taken on Pluto's previous rotation. Intriguing details are beginning to emerge in the bright material north of the dark region, in particular a series of bright and dark patches that are conspicuous just below the center of the disk in the right-hand image. In all three black-and-white views, the apparent jagged bottom edge of Pluto is the result of image processing. http://photojournal.jpl.nasa.gov/catalog/PIA19698

ICE MINERALOGY ACROSS AND INTO THE SURFACES OF PLUTO, TRITON, AND ERIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tegler, S. C.; Grundy, W. M.; Olkin, C. B.

We present three near-infrared spectra of Pluto taken with the Infrared Telescope Facility and SpeX, an optical spectrum of Triton taken with the MMT and the Red Channel Spectrograph, and previously published spectra of Pluto, Triton, and Eris. We combine these observations with a two-phase Hapke model and gain insight into the ice mineralogy on Pluto, Triton, and Eris. Specifically, we measure the methane-nitrogen mixing ratio across and into the surfaces of these icy dwarf planets. In addition, we present a laboratory experiment that demonstrates it is essential to model methane bands in spectra of icy dwarf planets with twomore » methane phases-one highly diluted by nitrogen and the other rich in methane. For Pluto, we find bulk, hemisphere-averaged, methane abundances of 9.1% {+-} 0.5%, 7.1% {+-} 0.4%, and 8.2% {+-} 0.3% for sub-Earth longitudes of 10 Degree-Sign , 125 Degree-Sign , and 257 Degree-Sign . Application of the Wilcoxon rank sum test to our measurements finds these small differences are statistically significant. For Triton, we find bulk, hemisphere-averaged, methane abundances of 5.0% {+-} 0.1% and 5.3% {+-} 0.4% for sub-Earth longitudes of 138 Degree-Sign and 314 Degree-Sign . Application of the Wilcoxon rank sum test to our measurements finds the differences are not statistically significant. For Eris, we find a bulk, hemisphere-averaged, methane abundance of 10% {+-} 2%. Pluto, Triton, and Eris do not exhibit a trend in methane-nitrogen mixing ratio with depth into their surfaces over the few centimeter range probed by these observations. This result is contrary to the expectation that since visible light penetrates deeper into a nitrogen-rich surface than the depths from which thermal emission emerges, net radiative heating at depth would drive preferential sublimation of nitrogen leading to an increase in the methane abundance with depth.« less

New Horizons: Bridge to the Beginning - to Pluto and Beyond

NASA Astrophysics Data System (ADS)

Weir, H. M.; Hallau, K. G.; Seaton, P.; Beisser, K.; New Horizons Education; Public Outreach Team

2010-12-01

Launched on Jan. 19, 2006, NASA’s New Horizons mission to Pluto and the Kuiper Belt will help us understand worlds at the edge of our solar system by making the first reconnaissance of Pluto and Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. However, New Horizons’ closest approach to Pluto will not occur until July 14, 2015, and the majority of the craft's time over the next 5 years will be spent in "hibernation." The Education and Public Outreach (EPO) team, however, will not be hibernating as we wait for New Horizons to reach its destination. With three distinct tools-- Educator Fellows, online learning modules and a planetarium program--the team seeks to excite and engage teachers, students and the public with information about the journey to Pluto and beyond. In the past year, the specially selected educators who participate as New Horizons Educator Fellows have trained more than 1,000 teachers across the U.S. on the New Horizons mission and the science behind it. Thousands more students, parents, educators, and citizens have learned about New Horizons from the mission's scientists, engineers and outreach professionals. New Horizons Fellows also distribute another EPO tool: online learning modules. These classroom-ready learning modules consist of educator guides, student handouts, detailed activities, and potential adaptations for students with special needs or disabilities. Some also offer online interactives to convey complex and dynamic concepts. The modules are web-accessible for both students and teachers, and are aligned with relevant national standards. The third tool is a highly visual way to engage the general public and supplement educational programs: a planetarium program that highlights the New Horizons mission from launch to destination Pluto. This program focuses on the engineering design of the spacecraft, with a focus on the concept of the electromagnetic spectrum. In the unique environment of the planetarium, users identify and view celestial objects at multiple wavelengths of light and discover how the instruments collect such data, which will help answer questions about Pluto, its moons, and the Kuiper Belt. The program is designed for educators and students at the middle school level and above.

Great debate probes Pluto's planetary credentials

NASA Astrophysics Data System (ADS)

Gwynne, Peter

2008-09-01

It had all the trappings of an Olympic boxing final: two fiery competitors, a partisan crowd and the attention of the global press. But no individual gold medalist emerged from the Great Planet Debate held last month in Baltimore to discuss what type of astronomical object Pluto really is. Rather, the contest between Neil de-Grasse Tyson, director of New York's Hayden Planetarium, and Mark Sykes of the University of Arizona's Planetary Science Institute provided a view of how science deals with controversial issues of definition.

Triton, Pluto, and Titan: A Comparison of Haze Photometry

NASA Astrophysics Data System (ADS)

Buratti, Bonnie J.; Hillier, John K.; Abgarian, Mary; Kutsop, Nicholas; Devins, Spencer; Mosher, Joel A.; Stern, S. Alan; Weaver, Harold A.; Olkin, Catherine; Young, Leslie; Ennico, Kimberly; New Horizons Science Team

2017-10-01

As Kuiper Belt Objects of similar size and albedo, Triton and Pluto were thought to be kindred bodies exhibiting like geologic histories and features, with possible seasonal volatile transport in their polar regions. During the flyby of Pluto in July 2015, active geological processes were observed on the planet (Stern et al., 2015), and a substantial haze layer that was more akin to Titan’s was observed (Gladstone et. al., 2016). Multiple haze layers were discovered surrounding the dwarf planet (Cheng et al. 2017).Using a radiative transfer model based on Chandrasekhar’s “Planetary Problem” of an optically thin atmosphere and a surface of arbitrary single scattering albedo and single particle phase function (Chandrasekhar, 1960; Hillier et al., 1990, 1991; Buratti et al., 2011), we have characterized the optical depth and surface properties of Pluto, Triton, and Titan. The forward-scattering properties of the haze can also be quantified by this model. Optical imaging data was analyzed for Triton and Pluto. For Titan we made use of published data on Titan (Tomasko and West, 2009) plus new Cassini Visual Infrared Mapping Spectrometer (VIMS) data, which spans the wavelength range between 0.35 and 5.2 microns, and which has several channels in the mid-infrared where both the haze opacity is relatively low and the atmosphere is optically thin. Pluto’s atmosphere is more optically thick than Triton’s but both are far thinner than Titan’s. The composition of Triton’s haze layer differs markedly from Titan’s. Observations of Pluto’s haze reveal a bluish color (Gladstone et al., 2016), but the reddish tint of possible haze deposits on the surface (Stern et al., 2015; Buratti et al., 2015) suggest Pluto’s haze composition is Titan-like. Institute of Technology. Government sponsorship acknowledged.

Chandra Observations of Pluto's Escaping Atmosphere in Support of the New Horizons Mission

NASA Astrophysics Data System (ADS)

McNutt, Ralph, Jr.

2013-09-01

Current models of Pluto's extended N2+CH4 atmosphere are still very uncertain, causing numerous difficulties in optimizing the New Horizons fast flyby operations plan for the dwarf planet. Applying knowledge gained from studying cometary X-ray emission, Chandra ACIS-S photometric imaging of X-rays produced by CXE between the solar wind and Pluto's atmosphere will address both the run of atmospheric density and the interaction of the solar wind with the extended Plutonian atmosphere. Determining the atmosphere's extent and amount of free molecular escape will aid the atmospheric sounding measurements of the NH ALICE instrument, while determining the x-ray luminosity will help the NH PEPSI instrument characterize the solar wind particle environment.

Volatile Transport on Pluto: First Results from the 2013 Observing Season

NASA Astrophysics Data System (ADS)

Buratti, B. J.; Dalba, P. A.; Hicks, M.; Chu, D.; O'Neill, A.; Chesley, J. P.

2013-12-01

With the New Horizons spacecraft due to encounter Pluto in slightly less than two years, close scrutiny of this dwarf ice planet has begun in earnest. Ground-based observations are especially critical for context and for a larger temporal excursion. Seasonal transport of volatiles should occur on Pluto, and this transport should be detectable through changes in its rotational light curve, once all variations due to viewing geometry have been modeled. Giving the steady increase observed in Pluto's atmospheric pressure over the past two decades, associated sublimation of frost from the surface has likely occurred, as predicted by volatile transport models. Rotational light curves of Pluto through time have been created for static frost models based on images from the Hubble Space Telescope. These models, which account for changes in viewing geometry, have been compared with observed light curves obtained between 1950 and 2013. No evidence for transport was evident prior to 2000. Observations from 2002 (Buie et al., 2010, Astron. J. 139, 1128) and 2007-2008 (Hicks et al. 2008, B.A.A.S. 40, 460) suggest changes in the frost pattern on Pluto's surface. New observations of Pluto's light curve from the 2013 season from Table Mountain Observatory show no evidence for the large transport of volatiles on Pluto's surface. Our data are the first measurement of a large opposition surge on Pluto similar to that seen on other icy bodies. Both Buie et al. (2010) and our observations from the 2012-2013 seasons show that Pluto is becoming more red in color. This observation makes sense if nitrogen is being removed from the surface to uncover a red, photolyzed substrate of methane. Funded by NASA.

Hubble Finds Two Chaotically Tumbling Pluto Moons

NASA Image and Video Library

2015-06-03

This computer animation illustrates how Pluto's moon Nix changes its spin unpredictably as it orbits the "double planet" Pluto-Charon. The view is from the surface of Pluto as the moon circles the Pluto-Charon system. This is a time-lapse view of the moon, compressing four years of motion into two minutes, with one complete orbit of Pluto-Charon every two seconds. (The apparent star movement rate is greatly slowed down for illustration purposes.) The animation is based on dynamical models of spinning bodies in complex gravitational fields — like the field produced by Pluto and Charon's motion about each other. Astronomers used this simulation to try to understand the unpredictable changes in reflected light from Nix as it orbits Pluto-Charon. They also found that Pluto's moon Hydra also undergoes chaotic spin. The football shape of both moons contributes to their wild motion. The consequences are that if you lived on either moon, you could not predict the time or direction the sun would rise the next morning. (The moon is too small for Hubble to resolve surface features, and so the surface textures used here are purely for illustration purposes.) Credit: NASA, ESA, M. Showalter (SETI Institute), and G. Bacon (STScI) Read more: www.nasa.gov/press-release/nasa-s-hubble-finds-pluto-s-mo... NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

The Copernicus project

NASA Technical Reports Server (NTRS)

Barnstable, Bob; Polte, Hans; Kepes, Paul; Walker, Kevin; Jacobs, Jeff; Williams, Stephen

1990-01-01

The Copernicus spacecraft, to be launched on May 4, 2009, is designed for scientific exploration of the planet Pluto. The main objectives of this exploration is to accurately determine the mass, density, and composition of the two bodies in the Pluto-Charon system. A further goal of the exploration is to obtain precise images of the system. The spacecraft will be designed for three axis stability control. It will use the latest technological advances to optimize the performance, reliability, and cost of the spacecraft. Due to the long duration of the mission, nominally 12.6 years, the spacecraft will be powered by a long lasting radioactive power source. Although this type of power may have some environmental drawbacks, currently it is the only available source that is suitable for this mission. The planned trajectory provides flybys of Jupiter and Saturn. These flybys provide an opportunity for scientific study of these planets in addition to Pluto. The information obtained on these flybys will supplement the data obtained by the Voyager and Galileo missions. The topics covered include: (1) scientific instrumentation; (2) mission management, planning, and costing; (3) power and propulsion system; (4) structural subsystem; (5) command, control, and communication; and (6) attitude and articulation control.

Solar system: Pluto is again a harbinger

NASA Astrophysics Data System (ADS)

Stern, S. Alan

2010-12-01

New astronomical and laboratory data show that the abundances of the two dominant ices, nitrogen and methane, on the surfaces of the Solar System's two largest dwarf planets are surprisingly similar - raising fresh questions.

Benefits of Nuclear Electric Propulsion for Outer Planet Exploration

NASA Technical Reports Server (NTRS)

Kos, Larry; Johnson, Les; Jones, Jonathan; Trausch, Ann; Eberle, Bill; Woodcock, Gordon; Brady, Hugh J. (Technical Monitor)

2002-01-01

Nuclear electric propulsion (NEP) offers significant benefits to missions for outer planet exploration. Reaching outer planet destinations, especially beyond Jupiter, is a struggle against time and distance. For relatively near missions, such as a Europa lander, conventional chemical propulsion and NEP offer similar performance and capabilities. For challenging missions such as a Pluto orbiter, neither chemical nor solar electric propulsion are capable while NEP offers acceptable performance. Three missions are compared in this paper: Europa lander, Pluto orbiter, and Titan sample return, illustrating how performance of conventional and advanced propulsion systems vary with increasing difficulty. The paper presents parametric trajectory performance data for NEP. Preliminary mass/performance estimates are provided for a Europa lander and a Titan sample return system, to derive net payloads for NEP. The NEP system delivers payloads and ascent/descent spacecraft to orbit around the target body, and for sample return, delivers the sample carrier system from Titan orbit to an Earth transfer trajectory. A representative scientific payload 500 kg was assumed, typical for a robotic mission. The resulting NEP systems are 100-kWe class, with specific impulse from 6000 to 9000 seconds.

Global Map of Pluto

NASA Image and Video Library

2015-07-27

The science team of NASA's New Horizons mission has produced an updated global map of the dwarf planet Pluto. The map includes all resolved images of the surface acquired between July 7-14, 2015, at pixel resolutions ranging from 40 kilometers (24 miles) on the Charon-facing hemisphere (left and right sides of the map) to 400 meters (1,250 feet) on the anti-Charon facing hemisphere (map center). Many additional images are expected in fall of 2015 and these will be used to complete the global map. http://photojournal.jpl.nasa.gov/catalog/PIA19858

NASA Planetary Surface Exploration

NASA Technical Reports Server (NTRS)

Hayati, Samad

1999-01-01

Managed for NASA by the California Institute of Technology, the Jet Propulsion Laboratory is the lead U.S. center for robotic exploration of the solar system. JPL spacecraft have visited all known planets except Pluto (a Pluto mission is currently under study). In addition to its work for NASA, JPL conducts tasks for a variety of other federal agencies. In addition, JPL manages the worldwide Deep Space Network, which communicates with spacecraft and conducts scientific investigations from its complexes in California's Mojave Desert near Goldstone; near Madrid, Spain; and near Canberra, Australia. JPL employs about 6000 people.

Reduction of EAO Positional Observations Database

NASA Astrophysics Data System (ADS)

Nefedyev, Yuri; Andreev, Alexey; Demina, Natalya; Churkin, Konstantin

2016-07-01

There is a large data bank of positional observations of Solar System bodies at Engelhadt Astronomical Observatory (EAO). The positional observations include the major planets, except Jupiter. Modern technologies replace classical methods of observations in astronomy and in astrometry as well. At the same time many positional observations have been gathered at astronomical observatories. So taking into account that observations of the past epochs have presenteda great value for astronomy and as times goes by their importance is growing it is obvious that positional astrometry will not lose its practical importance. This was noted in B3 XXIV IAU resolution by the General Assembly. The results of reduction of solar system bodies observations were published mainly in Proceeding of EAO and Transactions of Kazan City Astronomical Observatory. Earlier there have been made about three thousand observations at EAO and Zelenchuk station with the Zeiss telescope (D=400mm, f=2000mm), AFR-18 (photo visual, D=200, f=2000), refractor (D=400mm, f=3450mm), Meniscus camera (D=340mm, f=1200mm), Schmidt camera (D=350mm, f=2000mm). The major planets except Pluto and Neptune were observed with a special cassette chamber equipped with a rotating disk which had an open sector to reduce the brightness of the planets. The dimension of the sector was chosen accordingto the brightness of the planets. The disk was placed in the centre of the astrograph's field. The stars' true brightness was preserved. A large number of catalogues were compiled by the end of the 20th century. We used Tycho-2 catalogue for reducing our observations. As it is known the catalogue Tycho-2 (Tycho-2 catalogue, 2000) includes 2539913 stars. The stars' proper motions given in the catalogue were obtained by comparing positions from Tycho-2 with positions from the Astrographic Catalogue. Therefore they are considered to be highly accurate. The accuracy of stellar positions in Tycho-2 is about 60 mas and the accuracy of their proper motions is 2.5 mas/yr. The mean (O-C) values for Pluto were calculated for observations taken between 1985 and 1991. However, if we look at the period of 1988-1991 in detail, the values of (O-C)_{α} for Pluto with the Tycho-2 catalogue increase from 1,32" to 2,25". The values of (O-C)_{δ} are in the limits of -0,41" to -0,57". The large (O - C) values for Pluto in both coordinates can be explained by the uncertainties of its ephemeredes and probably by the oscillations of the photometric centre of the Pluto-Charon system. Similar results had been obtained earlier at EAO and Pulkovo observatory. The values of (O - C) for the other planets are within the accuracy of the positional method of observation. Positions of Venus, Mars, Saturn, Uranus, Neptune and Pluto in the system of the Tycho-2 catalogue were obtained. The coordinates of the planets are apparent exceptfor Pluto. In addition the work has been compared by the accuracy with the results obtained with using catalogues PPM and Tycho-2. The accuracy of the reduction of EAO planet observations based on the Tycho-2 catalogue is higher than that of the reduction with the PPM catalogues especially in right ascension. That is not surprising, since both the systematical and random errors are smaller in the Tycho-2 catalogue. We consider this demonstrates that rereduction of positional observations with improved catalogues can significantly improve the accuracy, and therefore the value, of old, and in the case of planets - unrepeatable, observations. At the present time at EAO there is a glass library which contains a large archive of photographic plates, covering the period of more than 90 years, and obtained by different telescopes:1) A photographic survey of the sky (FON) 30X30 - 1746 plates;2) Photographic catalogue (size 30X30) - 700 plates;3) The Moon with Stars - 612 plates;4) Positive images - 272 plates;5) Comets, asteroids, moons - 159 plates;Schmidt Telescope:6) Selected Areas of Kapteyn - 1500 plates;7) Comets and asteroids - 950 plates;8) Radio sources - 253 plates;9) Variable Stars - 350 plates;10) New and supernovae - 300 plates;11) Random objects - 250 plates;Meniscus telescope :12) Selected Areas of Kapteyn - 1070 (2130) plates.Total: 10292 plates. Today we are converting the astronomical plates into digital form. In order to get an acceptable size of final data (tens of MB) without loss of astronomical data some compression methods with resolution up to 20 microns will be used. Work was supported by grants RFBR 15-02-01638-a, 16-32-60071-mol-dk-a and 16-02-00496-a.

Breaking the BBC (Buoyancy Barriers to Cryovolcanism)

NASA Astrophysics Data System (ADS)

McGovern, P. J.; White, O. L.

2018-06-01

Like Australian table wines, Cryovolcanism has been poo-poohed, because of a perceived negative buoyancy problem. Here we point out that several basaltic planets have overcome far worse barriers, and calculate a scenario for cyrovolcanism on Pluto.

The fates of Solar system analogues with one additional distant planet

NASA Astrophysics Data System (ADS)

Veras, Dimitri

2016-12-01

The potential existence of a distant planet (`Planet Nine') in the Solar system has prompted a re-think about the evolution of planetary systems. As the Sun transitions from a main-sequence star into a white dwarf, Jupiter, Saturn, Uranus and Neptune are currently assumed to survive in expanded but otherwise unchanged orbits. However, a sufficiently distant and sufficiently massive extra planet would alter this quiescent end scenario through the combined effects of Solar giant branch mass-loss and Galactic tides. Here, I estimate bounds for the mass and orbit of a distant extra planet that would incite future instability in systems with a Sun-like star and giant planets with masses and orbits equivalent to those of Jupiter, Saturn, Uranus and Neptune. I find that this boundary is diffuse and strongly dependent on each of the distant planet's orbital parameters. Nevertheless, I claim that instability occurs more often than not when the planet is as massive as Jupiter and harbours a semimajor axis exceeding about 300 au, or has a mass of a super-Earth and a semimajor axis exceeding about 3000 au. These results hold for orbital pericentres ranging from 100 to at least 400 au. This instability scenario might represent a common occurrence, as potentially evidenced by the ubiquity of metal pollution in white dwarf atmospheres throughout the Galaxy.

Craters and ejecta on Pluto and Charon: Anticipated results from the New Horizons flyby

NASA Astrophysics Data System (ADS)

Bierhaus, Edward B.; Dones, Luke

2015-01-01

We examine the flux of bodies striking Pluto and Charon, and the nature of the crater populations that will form as a result of these impacts. Assuming impact speeds of 2 km/s and an impact angle of 45 ° , a 1 km impactor will form a 4.2 km diameter transient crater on Pluto, and a ∼5.0 km crater on Charon, as compared with 8-13 km for several mid-sized saturnian satellites and 8-10 km for the icy Galilean satellites. We predict that secondary craters will be present in the crater size-frequency distribution (SFD) for Pluto and Charon at sizes less than a few km, at spatial densities comparable to the range seen on the mid-sized saturnian satellites and distinctly less than seen on the icy Galilean satellites. Pluto should have more secondary craters formed per primary impact than Charon, so if neither crater population on these bodies is in saturation, Charon's crater SFD should be the "cleanest" reflection of the primary, impacting SFD. Ejecta from Pluto and Charon escape more efficiently from the combined system, relative to ejecta from a satellite in orbit around a giant planet, due to the absence of a large central body. We estimate that Kuiper Belt Objects (KBOs) with diameters larger than 1 km should strike Pluto and Charon on (nominal) timescales of 2.2 and 10 million years, respectively. These estimates are uncertain because the numbers of small KBOs are poorly constrained. Our estimated rates are smaller than earlier predictions of impact rates, primarily because we assume a KBO size distribution that is shallower overall than previous studies did. The impact rate, combined with the observed crater SFD, will enable estimates of relative and absolute age of different geologic units, should different geologic units exist. We explore two scenarios in regards to the crater population: (1) a shallow (differential power-law index of p ∼ 2 , i.e. for dN / dD ∝D-p), based on the crater SFD observed on young terrains of Galilean and saturnian satellites; and (2) a slightly steeper SFD (p ∼ 3), based on extrapolations of larger (∼100 km) KBOs from ground-based surveys. If the observed primary crater SFD, at diameters less than a few tens of km, is consistent with a differential power-law index p ∼ 2 , that will confirm that KBOs are deficient in small bodies relative to extrapolations from known ∼100 km KBOs, consistent with expectations derived from examination of crater populations in young terrains on the Galilean and saturnian satellites. If the crater SFD has p ⩾ 3 over all observed sizes, then that power-law index applies across the KBO population over at least two orders of magnitude (1 km to100 km objects), and there must be some process that erodes the small KBOs when they migrate to the Jupiter-Saturn region of the Solar System. Whatever SFD is observed, the primary crater population on Pluto and Charon will provide the strongest constraint on the SFD of small KBOs, which will be beyond the observational reach of ground- and space-based telescopes for years to come. This, in turn, will provide a fundamental constraint for further understanding of the evolution of this distant and compelling population of bodies beyond Neptune.

A Binary Planet in Color

NASA Image and Video Library

2015-07-23

This image from NASA New Horizons highlights the contrasting appearance of the two worlds: Charon is mostly gray, with a dark reddish polar cap, while Pluto shows a wide variety of subtle color variations. Pluto and Charon are shown in enhanced color in this image, which is the highest-resolution color image of the pair so far returned to Earth by New Horizons. It was taken at 06:49 UT on July 14, 2015, five hours before Pluto closest approach, from a range of 150,000 miles (250,000 kilometers), with the spacecraft's Ralph instrument. The image highlights the contrasting appearance of the two worlds: Charon is mostly gray, with a dark reddish polar cap, while Pluto shows a wide variety of subtle color variations, including yellowish patches on the north polar cap and subtly contrasting colors for the two halves of Pluto's "heart," informally named Tombaugh Regio, seen in the upper right quadrant of the image. In order to fit Pluto and Charon in the same frame in their correct relative positions, the image has been rotated so the north pole on both Pluto and Charon is pointing towards the upper left. The image was made with the blue, red, and near-infrared color filters of Ralph's Multispectral Visible Imaging Camera, and shows colors that are similar, but not identical, to what would be seen with the human eye, which is sensitive to a narrower range of wavelengths. http://photojournal.jpl.nasa.gov/catalog/PIA19856

The Chemistry of Pluto and its Satellites

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.

2017-01-01

Pluto's bulk composition and the composition of the surface layers hold clues to the origin and evolution of a number of other Solar System bodies of comparable size in the region beyond Neptune. The July 14, 2015 flyby of the Pluto system with the New Horizons spacecraft afforded the opportunity to corroborate and greatly improve discoveries about the planet and its satellites derived Earth-based studies. It also revealed extraordinary details of the surface and atmosphere of Pluto, as well as the geology and composition of Charon and two smaller satellites. With a mean density of 1.86 g/sq cm, the bulk composition of Pluto is about two-thirds anhydrous solar composition rocky material and one-third volatiles (primarily H2O in liquid and solid states) by mass, the surface is a veneer of ices dominated by N2, with smaller amounts of CH4 and CO, as well as limited exposures of H2O ice (considered to be "bedrock"). N2, CH4, and CO occur as solid solutions at temperature-dependent mutual concentrations, each component being soluble in the others. Frozen C2H6 as a minor component has also been identified. Sublimation and recondensation of N2, CH4, and CO over seasonal (248 y) and Milankovich-type megaseasons (approx. 3 My) result in the redistribution of these ices over time and with latitude control. Solid N2 is found in glaciers originating in higher elevations and flowing at the present time into a basin structure larger than the State of Texas, forming a convecting lens of N2 that overturns on a timescale of order 10 My. The varied colors of Pluto's landscape arise from the energetic processing of the surface ices in processes that break the simple molecules and reassemble complex organic structures consisting of groups of aromatic rings connected by aliphatic chains. When synthesized in the laboratory by UV or electron irradiation of a Pluto mix of ice, this material, called tholin, has colors closely similar to Pluto. The Pluto ice tholin analog contains carboxylic acids, urea, ketones, aldehydes, amines, and some nitriles. The largest satellite, Charon has density 1.70 g/sq cm and it is about 3/5 anhydrous solar composition rock, with the remainder in H2O ice. The surface H2O ice is infused in some way with NH3, probably as a hydrate, distributed nonuniformly, but to some degree related to geological structures. Pluto's atmosphere is N2, CH4, with CO, C2-hydrocarbons, HCN, and other molecules in trace but detectable amounts. The atmosphere supports a complex haze structure with about 20 discrete layers, and suspected clouds. The haze is presumed to be made of aggregates of complex hydrocarbons (tholins) produced by photolysis of the atmospheric gases, and with similar composition to the ice tholins made on the planet's surface. Urea and a suite of carboxylic acids are of interest for prebiotic and biological chemistries.

Pluto's elongated dark regions formed by the Charon-forming giant impact

NASA Astrophysics Data System (ADS)

Genda, Hidenori; Sekine, Yusuhito; Kamata, Shunichi; Funatsu, Taro

2017-04-01

The New Horizons spacecraft has found elongated dark areas in the equatorial region of Pluto, which were informally called "the Whale" or Cthulhu Region (Stern et al. 2015). Here we examine the possibility that the dark areas on Pluto were formed by thermal alterations and polymerization of interstellar volatiles caused by a Charon-forming giant impact. Pluto is one of the largest Kuiper belt objects, which is highly likely to contain various interstellar volatiles, including aldehyde and ammonia. The previous study (Cordy et al. 2011) shows that these interstellar volatiles are thermally polymerized in solutions at high temperatures, forming complex insoluble organic solids. Given the satellite-to-planet mass ratio, the Pluto-Charon system is suggested to be of a giant impact origin (Canup 2005). Impact-induced heating on Pluto could have converted these volatile into complex organic matter in solution near the surface, which may explain the presence of dark areas in the equatorial region of Pluto. Here, we produce complex organic matter for various temperatures by thermal polymerization of formaldehyde and ammonia in solutions. By measuring the UV-VIS absorption spectra of the produced organic matter, we found that the color of the solution changes to be dark if the temerature is above 50 degree C for months or more. This duration corresponds to the cooling timescale of a water pond with 500-km thickness. By using SPH code (Genda et al. 2015), we carried out many simulations of a giant impact, and we found that a molten hot pond with > 500-km thickness is formed around the equatorial region of Pluto by a Charon-forming giant impact, if the water/rock mixing mass ratio is less than 1 or if the pre-impact interior temperature is 150 K. Both the dark equatorial region and a Charon-sized moon are formed when the pre-impact Pluto is undifferentiated. To keep a rock-rich Pluto undifferentiated at time of the giant impact, Pluto may have been formed >100 Myrs after CAIs, and the giant impact may have occurred <100 Myrs after the Pluto's formation.

Pluto: Distribution of ices and coloring agents from New Horizons LEISA observations

NASA Astrophysics Data System (ADS)

Cruikshank, Dale P.; Grundy, William M.; Stern, S. Alan; Olkin, Catherine B.; Cook, Jason C.; Dalle Ore, Cristina M.; Binzel, Richard P.; Earle, Alissa M.; Ennico, Kimberly; Jennings, Donald E.; Howett, Carly J. A.; Linscott, Ivan R.; Lunsford, Allen W.; Parker, Alex H.; Parker, Joel W.; Protopapa, Silvia; Reuter, Dennis C.; Singer, Kelsi N.; Spencer, John R.; Tsang, Constantine C. C.; Verbiscer, Anne J.; Weaver, Harold A.; Young, Leslie A.

2015-11-01

Pluto was observed at high spatial resolution (maximum ~3 km/px) by the New Horizons LEISA imaging spectrometer. LEISA is a component of the Ralph instrument (Reuter, D.C., Stern, S.A., Scherrer, J., et al. 2008, Space Sci. Rev. 140, 129) and affords a spectral resolving power of 240 in the wavelength range 1.25-2.5 µm, and 560 in the range 2.1-2.25 µm. Spatially resolved spectra with LEISA are used to map the distributions of the known ices on Pluto (N2, CH4, CO) and to search for other surface components. The spatial distribution of volatile ices is compared with the distribution of the coloring agent(s) on Pluto's surface. The correlation of ice abundance and the degree of color (ranging from yellow to orange to dark red) is consistent with the presence of tholins, which are refractory organic solids of complex structure and high molecular weight, with colors consistent with those observed on Pluto. Tholins are readily synthesized in the laboratory by energetic processing of mixtures of the ices (N2, CH4, CO) known on Pluto's surface. We present results returned from the spacecraft to date obtained from the analysis of the high spatial resolution dataset obtained near the time of closest approach to the planet. Supported by NASA’s New Horizons project.

Hydrodynamic escape from planetary atmospheres

NASA Astrophysics Data System (ADS)

Tian, Feng

Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Due to the existence of a singularity point near the transonic point, it is difficult to find transonic steady state solutions by solving the time-independent hydrodynamic equations. In addition to that, most previous works assume that all energy driving the escape flow is deposited in one narrow layer. This assumption not only results in less accurate solutions to the hydrodynamic escape problem, but also makes it difficult to include other chemical and physical processes in the hydrodynamic escape models. In this work, a numerical model describing the transonic hydrodynamic escape from planetary atmospheres is developed. A robust solution technique is used to solve the time dependent hydrodynamic equations. The method has been validated in an isothermal atmosphere where an analytical solution is available. The hydrodynamic model is applied to 3 cases: hydrogen escape from small orbit extrasolar planets, hydrogen escape from a hydrogen rich early Earth's atmosphere, and nitrogen/methane escape from Pluto's atmosphere. Results of simulations on extrasolar planets are in good agreement with the observations of the transiting extrasolar planet HD209458b. Hydrodynamic escape of hydrogen from other hypothetical close-in extrasolar planets are simulated and the influence of hydrogen escape on the long-term evolution of these extrasolar planets are discussed. Simulations on early Earth suggest that hydrodynamic escape of hydrogen from a hydrogen rich early Earth's atmosphere is about two orders magnitude slower than the diffusion limited escape rate. A hydrogen rich early Earth's atmosphere could have been maintained by the balance between the hydrogen escape and the supply of hydrogen into the atmosphere by volcanic outgassing. Origin of life may have occurred in the organic soup ocean created by the efficient formation of prebiotic molecules in the hydrogen rich early Earth's atmosphere. Simulations show that hydrodynamic escape of nitrogen from Pluto is able to remove a ~3 km layer of ice over the age of the solar system. The escape flux of neutral nitrogen may interact with the solar wind at Pluto's orbit and may be detected by the New Horizon mission.

Two Faces of Pluto

NASA Image and Video Library

2015-07-01

This pair of approximately true color images of Pluto and its big moon Charon, taken by NASA's New Horizons spacecraft, highlight the dramatically different appearance of different sides of the dwarf planet, and reveal never-before-seen details on Pluto's varied surface. The views were made by combining high-resolution black-and-white images from the Long Range Reconnaissance Imager (LORRI) with color information from the lower-resolution color camera that is part of the Ralph instrument. The left-hand image shows the side of Pluto that always faces away from Charon -- this is the side that will be seen at highest resolution by New Horizons when it makes its close approach to Pluto on July 14th. This hemisphere is dominated by a very dark region that extends along the equator and is redder than its surroundings, alongside a strikingly bright, paler-colored region which straddles the equator on the right-hand side of the disk. The opposite hemisphere, the side that faces Charon, is seen in the right-hand image. The most dramatic feature on this side of Pluto is a row of dark dots arranged along the equator. The origin of all these features is still mysterious, but may be revealed in the much more detailed images that will be obtained as the spacecraft continues its approach to Pluto. In both images, Charon shows a darker and grayer color than Pluto, and a conspicuous dark polar region. The left-hand image was obtained at 5:37 UT on June 25th 2015, at a distance from Pluto of 22.9 million kilometers (14.3 million miles) and has a central longitude of 152 degrees. The right-hand image was obtained at 23:15 UT on June 27th 2015, at a distance from Pluto of 19.7 million kilometers (12.2 million miles) with a central longitude of 358 degrees. Insets show the orientation of Pluto in each image -- the solid lines mark the equator and the prime meridian, which is defined to be the longitude that always faces Charon. The smallest visible features are about 200 km (120 miles) across. http://photojournal.jpl.nasa.gov/catalog/PIA19693

Final Hazard Search

NASA Image and Video Library

2015-07-08

This single frame from a four-frame movie shows New Horizons' final deep search for hazardous material around Pluto, obtained on July 1, 2015. These data allow a highly sensitive search for any new moons. The images were taken with the spacecraft's Long Range Reconnaissance Imager (LORRI) over a 100-minute period, and were the final observations in the series of dedicated searches for hazards in the Pluto system which began on May 11. The images show all five known satellites of Pluto moving in their orbits around the dwarf planet, but analysis of these data has so far not revealed the existence of any additional moons. This means that any undiscovered Plutonian moons further than a few thousand miles from Pluto must be smaller than about 1 mile (1.6 kilometers) in diameter, if their surfaces have similar brightness to Pluto's big moon Charon. For comparison, Pluto's faintest known moon, Styx, which is conspicuous in the lower left quadrant of these images, is about 4 miles (7 kilometers) across, assuming the same surface brightness. The absence of additional moons, and also the absence of detectable rings in the hazard search data, imply that the spacecraft is very unlikely to be damaged by collisions with rings, or dust particles ejected from moons, during its high-speed passage through the Pluto system. The four movie frames were taken at 16:28, 16:38, 17:52, and 18:04 UTC on July 1, from a range of 9.4 million miles (15.2 million kilometers). Each frame is a mosaic of four sets of overlapping images, with a total exposure time of 120 seconds. The images have been heavily processed to remove the glare of Pluto and Charon, and the dense background of stars, though blemishes remain at the locations of many of the brighter stars. The "tails" extending to the right or downward from Pluto and Charon are camera artifacts caused by the extreme overexposure of both objects. Pluto and its five moons Charon, Styx, Nix, Kerberos and Hydra are identified by their initials, and their orbits around the center of gravity of the system (which is located just outside Pluto itself) are also shown. http://photojournal.jpl.nasa.gov/catalog/PIA19701

A search for stellar occultations by Uranus, Neptune, Pluto, and their satellites: 1990-1999

NASA Technical Reports Server (NTRS)

Mink, Douglas J.

1991-01-01

A search for occultations of stars by Uranus, Neptune, and Pluto between 1990 and 1999 was carried out by combining ephemeris information and star positions using very accurate occultation modeling software. Stars from both the Space Telescope Guide Catalog and photographic plates taken by Arnold Klemola at Lick Observatory were compared with planet positions from the JPL DE-130 ephemeris, with local modifications for Pluto and Charon. Some 666 possible occultations by the Uranian ring, 143 possible occultations by Neptune, and 40 possible occultations by Pluto and/or Charon were found among stars with visual magnitudes as faint as 16. Before the star positions could be obtained, the occultation prediction software was used to aid many observers in observing the occultation of 28 Sagitarii by Saturn in July 1989. As a test on other outer solar system objects, 17 possible occultations were found in a search of the Guide Star Catalog for occultations by 2060 Chiron, and interesting object between Saturn and Uranus which shows both cometary and asteroidal properties.

A search for stellar occultations by Uranus, Neptune, Pluto, and their satellites: 1990-1999

NASA Astrophysics Data System (ADS)

Mink, Douglas J.

1991-03-01

A search for occultations of stars by Uranus, Neptune, and Pluto between 1990 and 1999 was carried out by combining ephemeris information and star positions using very accurate occultation modeling software. Stars from both the Space Telescope Guide Catalog and photographic plates taken by Arnold Klemola at Lick Observatory were compared with planet positions from the JPL DE-130 ephemeris, with local modifications for Pluto and Charon. Some 666 possible occultations by the Uranian ring, 143 possible occultations by Neptune, and 40 possible occultations by Pluto and/or Charon were found among stars with visual magnitudes as faint as 16. Before the star positions could be obtained, the occultation prediction software was used to aid many observers in observing the occultation of 28 Sagitarii by Saturn in July 1989. As a test on other outer solar system objects, 17 possible occultations were found in a search of the Guide Star Catalog for occultations by 2060 Chiron, and interesting object between Saturn and Uranus which shows both cometary and asteroidal properties.

A Remarkable World

NASA Image and Video Library

2015-07-03

This image of Pluto and its big moon Charon was taken by NASA's New Horizons spacecraft at 04:15 (UTC) on July 1, 2015, and shows the clearest view yet of the sides of Pluto and Charon that will be studied in great detail during New Horizons' closest approach to the dwarf planet on July 14, 2015. There will be just two more rotations of Pluto and Charon, and two more orbits about their mutual center of gravity, between the time of this image and closest approach (the rotation period of the system is 6.4 days). The image, which has been sharpened by the image processing technique known as deconvolution, shows details as small as about 160 kilometers (100 miles). The highest-resolution images of this side of Pluto, taken on July 14, will show details that are 1,000 times smaller. New Horizons is revealing Pluto to be a world that, at this point, looks like no other in the solar system. Its equatorial regions are occupied by a discontinuous band of very dark material, which is interrupted on this hemisphere by a very bright region which appears sharp-edged at the resolution of the image. The north polar region is blander, but shows a distinctive darker southern boundary where it meets the higher-contrast equatorial regions. The origin of these remarkable features is still unknown, though some of them might be related to seasonal movement of frost across Pluto's surface. Charon, in contrast, still shows few details other than the dark polar region. The image was taken by New Horizons' Long Range Reconnaissance Imager (LORRI ) at a distance from Pluto of 15.8 million kilometers (9.8 million miles) and has a central longitude of 177 degrees on Pluto and 357 degrees on Charon. The inset shows the orientation of Pluto- the solid lines mark the equator and the prime meridian, which is defined to be the longitude that always faces Charon. http://photojournal.jpl.nasa.gov/catalog/PIA19694

Our Solar System's Cousin?

NASA Technical Reports Server (NTRS)

2007-01-01

This artist's concept illustrates two planetary systems -- 55 Cancri (top) and our own. Blue lines show the orbits of planets, including the dwarf planet Pluto in our solar system. The 55 Cancri system is currently the closest known analogue to our solar system, yet there are some fundamental differences.

The similarities begin with the stars themselves, which are about the same mass and age. Both stars also host big families of planets. Our solar system has eight planets, while 55 Cancri has five, making it the record-holder for having the most known exoplanets. In fact, 55 Cancri could have additional planets, possibly even rocky ones that are too small to be seen with current technologies. All of the planets in the two systems have nearly circular orbits.

In addition, both planetary systems have giant planets in their outer regions. The giant located far away from 55 Cancri is four times the mass of our Jupiter, and completes one orbit every 14 years at a distance of five times that between Earth and the sun (about 868 million kilometers or 539 million miles). Our Jupiter completes one orbit around the sun every 11.9 years, also at about five times the Earth-sun distance (778 million kilometers or 483 million miles). Fifty-five Cancri is still the only known star besides ours with a planet in a distant Jupiter-like orbit. Both systems also contain inner planets that are less massive than their outer planets.

The differences begin with the planets' masses. The planets orbiting 55 Cancri are all larger than Earth, and represent a 'souped-up' version of our own solar system. In fact, this is the first star that boasts more giant planets than our sun!

The arrangement of the planetary systems is also different. The inner four planets of 55 Cancri are all closer to the star than Earth is to the sun. The closest, about the mass of Uranus, whips around the star in just under three days at a distance of approximately 5.6 million kilometers (3.5 million miles). The second planet out from the star is a little smaller than Jupiter and completes one orbit every 14.7 days at a distance of approximately 17.9 million kilometers (11.2 million miles). The third planet out from the star is similar in mass to Saturn and completes one orbit every 44 days at a distance of approximately 35.9 million kilometers (22.3 million miles). The fourth planet is about half the mass of Saturn, orbits every 260 days and is approximately 116.7 million kilometers (72.5 million miles) away from the star.

Biology on the outer planets. [life possibility in atmospheres and moons

NASA Technical Reports Server (NTRS)

Young, R. S.; Macelroy, R. D.

1976-01-01

A brief review is given of information on the structure and composition of the outer planets and the organic reactions that may be occurring on them. The possibility of life arising or surviving in the atmospheres of these planets is considered, and the problem of contamination during future unmanned missions is assessed. Atmospheric models or available atmospheric data are reviewed for Jupiter, Saturn, Uranus, Neptune, Pluto, the Galilean satellites, and Titan. The presence of biologically interesting gases on Jupiter and Saturn is discussed, requirements for life on Jupiter are summarized, and possible sources of biological energy are examined. Proposals are made for protecting these planets and satellites from biological contamination by spacecraftborne terrestrial organisms.

The Pluto-Charon System

NASA Astrophysics Data System (ADS)

Grundy, Will

2018-05-01

Pluto orbits the Sun at a mean distance of 39 AU, with an orbital period of 248 Earth years. Its orbit is just eccentric enough to cross that of Neptune. They never collide thanks to a 2:3 mean-motion resonance: Pluto completes two orbits of the Sun for every three by Neptune. The Pluto system consists of Pluto and its large satellite Charon, plus four small satellites: Styx, Nix, Kerberos, and Hydra. Pluto and Charon are spherical bodies, with diameters of 2377 and 1212 km, respectively. They are tidally locked to one another such that each spins about its axis with the same 6.39 day period as their mutual orbit about their common barycenter. Pluto's surface is dominated by frozen volatiles nitrogen, methane, and carbon monoxide. Their vapor pressure supports an atmosphere with multiple layers of photochemical hazes. Pluto's equator is marked by a belt of dark red maculae, where the photochemical haze has accumulated over time. Some regions are ancient and cratered, while others are geologically active via processes including sublimation and condensation, glaciation, and eruption of material from the subsurface. The surfaces of the satellites are dominated by water ice. Charon has dark red polar stains produced from chemistry fed by Pluto's escaping atmosphere. The existence of a planet beyond Neptune had been postulated by Percival Lowell and William Pickering in the early 20th century, to account for supposed clustering in comet aphelia and perturbations of the orbit of Uranus. Both lines of evidence turned out to be spurious, but they motivated a series of searches that culminated in Clyde Tombaugh's discovery of Pluto in 1930, at the observatory Lowell had founded in Arizona. Over subsequent decades, basic facts about Pluto were hard-won through application of technological advances in astronomical instrumentation. The progression from photographic plates, through photoelectric photometers, to digital array detectors, space-based telescopes, and ultimately, direct exploration by robotic spacecraft each revealed more about Pluto. A key breakthrough came in 1978 with the discovery of Charon by Christy and Harrington. Charon's orbit revealed the mass of the system. Observations of stellar occultations constrained the sizes of Pluto and Charon, and enabled the detection of Pluto's atmosphere in 1988. Spectroscopic instruments revealed Pluto's volatile ices. In a series of mutual events from 1985 through 1990, Pluto and Charon alternated in passing in front of the other as seen from Earth. Observations of these events provided additional constraints on their sizes and albedo patterns and revealed their distinct compositions. Hubble Space Telescope's vantage above Earth's atmosphere enabled further mapping of Pluto's albedo patterns and the discovery of the small satellites. NASA's New Horizons spacecraft flew through the system in 2015. Its instruments mapped the diversity and compositions of geological features on Pluto and Charon and provided detailed information on Pluto's atmosphere and its interaction with the solar wind.

The Binary Fission Model for the Formation of the Pluto system

NASA Astrophysics Data System (ADS)

Prentice, Andrew

2016-10-01

The ratio F of the mass of Pluto (P) to Charon (C), viz. F ≈ 8:1, is the largest ratio of any planet-satellite pair in the solar system. Another measure of the PC binary is its normalized angular momentum density J (see McKinnon 1989). Analysis of astrometric data (Brozovic et al 2015) acquired before the New Horizons (NH) arrival at Pluto and new measurements made by NH (Stern et al 2015) show that J = 0.39. Yet these F & J values are ones expected if the PC binary had formed by the rotational fission of a single liquid mass (Darwin 1902; Lyttleton 1953). At first glance, therefore, the fission model seems to be a viable model for the formation of the Pluto system. In fact, Prentice (1993 Aust J Astron 5 111) had used this model to successfully predict the existence of several moons orbiting beyond Charon, before their discovery in 2005-2012. The main problem with the fission model is that the observed mean density of Charon, namely 1.70 g/cm3, greatly exceeds that of water ice. Charon thus could not have once been a globe of pure water. Here I review the fission model within the framework of the modern Laplacian theory of solar system origin (Prentice 1978 Moon Planets 19 341; 2006 PASA 23 1) and the NH results. I assume that Pluto and Charon were initially a single object (proto-Pluto [p-P]) which had condensed within the same gas ring shed by the proto-solar cloud at orbital distance ~43 AU, where the Kuiper belt was born. The temperature of this gas ring is 26 K and the mean orbit pressure is 1.3 × 10-9 bar. After the gas ring is shed, chemical condensation takes place. The bulk chemical composition of the condensate is anhydrous rock (mass fraction 0.5255), graphite (0.0163), water ice (0.1858), CO2 ice (0.2211) and methane ice (0.0513). Next I assume that melting of the ices in p-P takes place through the decay of short-lived radioactive nuclides, thus causing internal segregation of the rock & graphite. Settling of heavy grains to the centre lowers the MOI of p-P, so triggering rotational disruption. Pluto's moons would then form from liquid water and liquid CO2, as well as entrained rock-graphite grains. Charon's mean density implies that the rock-graphite mass fraction of the fissioned mass was ˜0.41.

Heterogeneous and Evolving Distributions of Pluto's Volatile Surface Ices

NASA Astrophysics Data System (ADS)

Grundy, William M.; Olkin, C. B.; Young, L. A.; Buie, M. W.; Young, E. F.

2013-10-01

We report observations of Pluto's 0.8 to 2.4 µm reflectance spectrum with IRTF/SpeX on 70 nights over the 13 years from 2001 to 2013. The spectra show numerous vibrational absorption features of simple molecules CH4, CO, and N2 condensed as ices on Pluto's surface. These absorptions are modulated by the planet's 6.39 day rotation period, enabling us to constrain the longitudinal distributions of the three ices. Absorptions of CO and N2 are concentrated on Pluto's anti-Charon hemisphere, unlike absorptions of less volatile CH4 ice that are offset by roughly 90° from the longitude of maximum CO and N2 absorption. In addition to the diurnal/longitudinal variations, the spectra show longer term trends. On decadal timescales, Pluto's stronger CH4 absorption bands have deepened, while the amplitude of their diurnal variation has diminished, consistent with additional CH4 absorption by high northern latitude regions rotating into view as the sub-Earth latitude moves north (as defined by the system's angular momentum vector). Unlike the CH4 absorptions, Pluto's CO and N2 absorptions are declining over time, suggesting more equatorial or southerly distributions of those species. The authors gratefully thank the staff of IRTF for their tremendous assistance over the dozen+ years of this project. The work was funded in part by NSF grants AST-0407214 and AST-0085614 and NASA grants NAG5-4210 and NAG5-12516.

Reorientation and faulting of Pluto due to volatile loading within Sputnik Planitia

NASA Astrophysics Data System (ADS)

Keane, James T.; Matsuyama, Isamu; Kamata, Shunichi; Steckloff, Jordan K.

2016-12-01

Pluto is an astoundingly diverse, geologically dynamic world. The dominant feature is Sputnik Planitia—a tear-drop-shaped topographic depression approximately 1,000 kilometres in diameter possibly representing an ancient impact basin. The interior of Sputnik Planitia is characterized by a smooth, craterless plain three to four kilometres beneath the surrounding rugged uplands, and represents the surface of a massive unit of actively convecting volatile ices (N2, CH4 and CO) several kilometres thick. This large feature is very near the Pluto-Charon tidal axis. Here we report that the location of Sputnik Planitia is the natural consequence of the sequestration of volatile ices within the basin and the resulting reorientation (true polar wander) of Pluto. Loading of volatile ices within a basin the size of Sputnik Planitia can substantially alter Pluto’s inertia tensor, resulting in a reorientation of the dwarf planet of around 60 degrees with respect to the rotational and tidal axes. The combination of this reorientation, loading and global expansion due to the freezing of a possible subsurface ocean generates stresses within the planet’s lithosphere, resulting in a global network of extensional faults that closely replicate the observed fault networks on Pluto. Sputnik Planitia probably formed northwest of its present location, and was loaded with volatiles over million-year timescales as a result of volatile transport cycles on Pluto. Pluto’s past, present and future orientation is controlled by feedbacks between volatile sublimation and condensation, changing insolation conditions and Pluto’s interior structure.

KSC-05pd2273

NASA Image and Video Library

2005-09-29

KENNEDY SPACE CENTER, FLA. - On the Shuttle Landing Facility at NASA Kennedy Space Center, the Atlas V fairing halves for the New Horizons spacecraft have been offloaded from the Russian cargo plane (background). The fairing halves will be transported to Astrotech Space Operations in Titusville. The fairing later will be placed around the New Horizons spacecraft in the Payload Hazardous Service Facility. A fairing protects a spacecraft during launch and flight through the atmosphere. Once in space, it is jettisoned. The Lockheed Martin Atlas V is the launch vehicle for the New Horizons spacecraft, which is designed to make the first reconnaissance of Pluto and Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and its moon, Charon, in July 2015.

KSC-05pd2274

NASA Image and Video Library

2005-09-29

KENNEDY SPACE CENTER, FLA. - On the Shuttle Landing Facility at NASA Kennedy Space Center, one of the Atlas V fairing halves for the New Horizons spacecraft is offloaded from the Russian cargo plane. The fairing halves will be transported to Astrotech Space Operations in Titusville. The fairing later will be placed around the New Horizons spacecraft in the Payload Hazardous Service Facility. A fairing protects a spacecraft during launch and flight through the atmosphere. Once in space, it is jettisoned. The Lockheed Martin Atlas V is the launch vehicle for the New Horizons spacecraft, which is designed to make the first reconnaissance of Pluto and Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and its moon, Charon, in July 2015.

KSC-05pd2271

NASA Image and Video Library

2005-09-29

KENNEDY SPACE CENTER, FLA. - A Russian cargo plane sits on the Shuttle Landing Facility at NASA Kennedy Space Center with the Atlas V fairing for the New Horizons spacecraft inside. The two fairing halves will be removed, loaded onto trucks and transported to Astrotech Space Operations in Titusville. The fairing later will be placed around the New Horizons spacecraft in the Payload Hazardous Service Facility. A fairing protects a spacecraft during launch and flight through the atmosphere. Once in space, it is jettisoned. The Lockheed Martin Atlas V is the launch vehicle for the New Horizons spacecraft, which is designed to make the first reconnaissance of Pluto and Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. The mission will then visit one or more objects in the Kuiper Belt region beyond Neptune. New Horizons is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in February or March 2007, and reach Pluto and its moon, Charon, in July 2015.

Measuring the Size of a Small, Frost World

NASA Astrophysics Data System (ADS)

2006-01-01

Observing a very rare occultation of a star by Pluto's satellite Charon from three different sites, including Paranal, home of the VLT, astronomers were able to determine with great accuracy the radius and density of the satellite to the farthest planet. The density, 1.71 that of water, is indicative of an icy body with about slightly more than half of rocks. The observations also put strong constraints on the existence of an atmosphere around Charon. ESO PR Photo 02a/06 ESO PR Photo 02a/06 Artist's Impression of the Pluto-Charon system Since its discovery in 1978, Charon and Pluto have appeared to form a double planet, rather than a planet-satellite couple. Actually, Charon is about twice as small as Pluto in size, and about eight times less massive. However, there have been considerable discussions concerning the precise radii of Pluto and Charon, as well as about the presence of a tenuous atmosphere around Charon. In August 2004, Australian amateur astronomer Dave Herald predicted that the 15-magnitude star UCAC2 26257135 should be occulted by Charon on 11 July 2005. The occultation would be observable from some parts of South America, including Cerro Paranal, in the northern Atacama Desert, the location of ESO's Very Large Telescope (VLT). Stellar occultations have proved to be powerful tools to both measure sizes - at km-level accuracy, i.e. a factor ten better than what is feasible with other techniques - and detect very tenuous atmosphere - at microbar levels or less. Unfortunately, in the case of Charon, such occultations are extremely rare, owing to the very small angular diameter of the satellite on the sky: 55 milli-arcsec, i.e. the size of a one Euro coin observed from 100 km away! This explains why only one occultation by Charon was ever observed before 2005, namely on 7 April 1980 by Alistair Walker, from the South Africa Astronomical Observatory. Similarly, only in 1985, 1988 and 2002 could astronomers observe stellar occultations by Pluto. Quite surprisingly, the 2002 event showed that Pluto's atmospheric pressure had increased by a factor of two in four years (ESO PHOT 21/02). "Several factors, however, have boosted our odds for witnessing occultations of Charon," said Bruno Sicardy, from Paris Observatory (France) and lead author of the paper reporting the results. "First, larger telescopes now give access to fainter stars, thus multiplying the candidates for occultations. Secondly, stellar catalogues have become much more precise, allowing us to do better predictions. And, finally, the Pluto-Charon system is presently crossing the Milky Way, thereby increasing the likelihood of an occultation." ESO PR Photo 02b/06 ESO PR Photo 02b/06 The Pluto-Charon System (NACO/VLT) The July 2005 event was eventually observed from Paranal with Yepun, the fourth Unit Telescope of the VLT, equipped with the adaptive optics instrument NACO, as well as with the 0.5m "Campo Catino Austral Telescope" at San Pedro de Atacama (Chile), and with the 2.15m "Jorge Sahade" telescope at Cerro El Leoncito (Argentina). An accurate timing of the occultation seen at the three sites provides the most accurate measurement of Charon's size: its radius is found to be 603.6 km, with an error of the order of 5 km. This accuracy now allows astronomers to pin Charon's density down to 1.71 that of water, indicative of an icy body with about slightly more than half of rocks. Quite remarkably, Charon's density is now measured with much more precision than Pluto's. ESO PR Photo 02c/06 ESO PR Photo 02c/06 Charon's Occultation on July 11, 2005 Thanks to these observations, Sicardy and his collaborators could determine that if an tenuous atmosphere exists on Charon, linking it to the freezing ­-220­ degrees centigrade or so surface, its pressure has to be less than one tenth of a millionth that at the surface of the Earth, or 0.1 microbar, assuming that it is constituted entirely of nitrogen. A similar upper limit is derived for a gas like carbon monoxide. This is more than a factor one hundred smaller than Pluto's surface pressure, which is estimated to be in the range 10-15 microbars. "Comparing Pluto and Charon, we seem to cross a borderline between bodies which may have bound atmospheres - like Pluto - and airless bodies like Charon", said Olivier Hainaut, from ESO and member of the team. The observations also indicate that methane ice, if present, should be restricted to very cold regions of the surface. Similarly, nitrogen ice would be confined at best to high northern latitudes or permanently shadowed regions of Charon. As Pluto and its satellite sweep across the Milky Way, observations of more occultations will be tempted from the ground, while the NASA's Pluto-Kuiper Belt Mission, to be launched in January 2006, will be travelling towards the planet, that it should reach in July 2015. A report of these results is to be published in the January 5, 2006 issue of Nature ("Charon's size and upper limit on its atmosphere from a stellar occultation", by B. Sicardy, A. Bellucci, E. Gendron, F. Lacombe, S. Lacour, J. Lecacheux, E. Lellouch, S. Renner, S. Pau, F. Roques, T. Widemann, F. Colas, F. Vachier, N. Ageorges, O. Hainaut, O. Marco, W. Beisker, E. Hummel, C. Feinstein, H. Levato, A. Maury, E. Frappa, B. Gaillard, M. Lavayssière, M. Di Sora, F. Mallia, G. Masi, R. Behrend, F. Carrier, O. Mousis, P. Rousselot, A. Alvarez-Candal, D. Lazzaro, C. Veiga, A.H. Andrei, M. Assafin, D.N. da Silva Neto, R. Vieira Martins, C. Jacques, E. Pimentel, D. Weaver, J.-F Lecampion, F. Doncel, T. Momiyama, and G. Tancredi). High resolution images and their captions are available on this page.

Pluto is the new Mars!

NASA Technical Reports Server (NTRS)

Moore, Jeffrey M.; Mckinnon, William B.; Spencer, John R.; Howard, Alan D.; Grundy, William M.; Stern, S. Alan; Weaver, Harold A.; Young, Leslie A.; Ennico, Kimberly; Olkin, Cathy

2016-01-01

Data from NASA's New Horizons encounter with Pluto in July 2015 revealed an astoundingly complex world. The surface seen on the encounter hemisphere ranged in age from ancient to recent. A vast craterless plain of slowly convecting solid nitrogen resides in a deep primordial impact basin, reminiscent of young enigmatic deposits in Mars' Hellas basin. Like Mars, regions of Pluto are dominated by valleys, though the Pluto valleys are thought to be carved by nitrogen glaciers. Pluto has fretted terrain and halo craters. Pluto is cut by tectonics of several different ages. Like Mars, vast tracts on Pluto are mantled by dust and volatiles. Just as on Mars, Pluto has landscapes that systematically vary with latitude due to past and present seasonal (and mega-seasonal) effects on two major volatiles. On Mars, those volatiles are H2O and CO2; on Pluto they are CH4 and N2. Like Mars, some landscapes on Pluto defy easy explanation. In the Plutonian arctic there is a region of large (approx. 40 km across) deep (approx. 3-4 km) pits that probably could not be formed by sublimation, or any other single process, alone. Equally bizarre is the Bladed terrain, which is composed of fields of often roughly aligned blade-like ridges covering the flanks and crests of broad regional swells. Topping the unexpected are two large mounds approximately150 km across, approx. 5-6 km high, with great central depressions at their summits. The central depressions are almost as deep as the mounds are tall. These mounds have many of the characteristics of volcanic mountains seen on Mars and elsewhere in the inner solar system. Hypotheses for the formation of these Plutonian mounds so far all have challenges, principally revolving around the need for H2O ice to support their relief and the difficulty imagining mechanisms that would mobilize H2O. From the perspective of one year after the encounter, our appreciation of the extent of Pluto's diversity and complexity is quite reminiscent of the perspective the science community had of Mars, with similar quality data sets, soon after the early reconnaissance of that planet in the late 1960s and early 70s. So certainly in this sense, Pluto is the new Mars.

How Planet Nine could change the fate of the Solar system

NASA Astrophysics Data System (ADS)

Veras, D.

2017-09-01

The potential existence of a distant planet ('Planet Nine') in the Solar system has prompted a re-think about the evolution of planetary systems. As the Sun transitions from a main-sequence star into a white dwarf, Jupiter, Saturn, Uranus and Neptune are currently assumed to survive in expanded but otherwise unchanged orbits. However, a sufficiently distant and sufficiently massive extra planet would alter this quiescent end scenario through the combined effects of Solar giant branch mass-loss and Galactic tides. Here I estimate bounds for the mass and orbit of a distant extra planet that would incite future instability in systems with a Sun-like star and giant planets with masses and orbits equivalent to those of Jupiter, Saturn, Uranus and Neptune. I find that this boundary is diffuse and strongly dependent on each of the distant planet's orbital parameters. Nevertheless, I claim that instability occurs more often than not when the planet is as massive as Jupiter and harbours a semimajor axis exceeding about 300 au, or has a mass of a super-Earth and a semimajor axis exceeding about 3000 au. These results hold for orbital pericentres ranging from 100 to at least 400 au. This instability scenario might represent a common occurrence, as potentially evidenced by the ubiquity of metal pollution in white dwarf atmospheres throughout the Galaxy.

Upper limits to the fractionation of isotopes due to atmospheric escape: Implications for potential 14N/15N in Pluto's atmosphere

NASA Astrophysics Data System (ADS)

Mandt, K.; Mousis, O.

2014-12-01

Formation and evolution of the solar system is studied in part using stable isotope ratios that are presumed to be primordial, or representative of conditions in the protosolar Nebula. Comets, meteorites and giant planet atmospheres provide measurements that can reasonably be presumed to represent primordial conditions while the terrestrial planets, Pluto and Saturn's moon Titan have atmospheres that have evolved over the history of the solar system. The stable isotope ratios measured in these atmospheres are, therefore, first a valuable tool for evaluating the history of atmospheric escape and once escape is constrained can provide indications of conditions of formation. D/H ratios in the atmosphere of Venus provide indications of the amount of water lost from Venus over the history of the solar system, while several isotope ratios in the atmosphere of Mars provide evidence for long-term erosion of the atmosphere. We have recently demonstrated that the nitrogen ratios, 14N/15N, in Titan's atmosphere cannot evolve significantly over the history of the solar system and that the primordial ratio for Titan must have been similar to the value recently measured for NH3 in comets. This implies that the building blocks for Titan formed in the protosolar nebula rather than in the warmer subnebula surrounding Saturn at the end of its formation. Our result strongly contrasts with works showing that 14N/15N in the atmosphere of Mars can easily fractionate from the terrestrial value to its current value due to escape processes within the lifetime of the solar system. The difference between how nitrogen fractionates in Mars and Titan's atmospheres presents a puzzle for the fractionation of isotopes in an atmosphere due to atmospheric escape. Here, we present a method aiming at determining an upper limit to the amount of fractionation allowed to occur due to escape, which is a function of the escape flux and the column density of the atmospheric constituent. Through this approach, we demonstrate that fractionation on Titan is more limited than on Mars. When applied to Pluto, we find that any potential measurement of 14N/15N in Pluto's atmosphere can constrain the type of escape occurring from Pluto's atmosphere and possibly the source of nitrogen for Pluto.

Chairmanship of the Neptune/Pluto Outer Planets Science Working Group

NASA Technical Reports Server (NTRS)

Stern, S. Alan

1992-01-01

The Outer Planets Science Working Group (OPSWG) is the NASA Solar System Exploration Division (SSED) scientific steering committee for the Outer Solar Systems missions. The FY92 activities of OPSWG are summarized. A set of objectives for OPSWG over FY93 are described. OPSWG's activities for subsequent years are outlined. A paper which examines scientific questions motivating renewed exploration of the Neptune/Triton system and which reviews the technical results of the mission studies completed to date is included in the appendix.

Long-term surface temperature modeling of Pluto

NASA Astrophysics Data System (ADS)

Earle, Alissa M.; Binzel, Richard P.; Young, Leslie A.; Stern, S. A.; Ennico, K.; Grundy, W.; Olkin, C. B.; Weaver, H. A.; New Horizons Geology and Geophysics Imaging Team

2017-05-01

NASA's New Horizons' reconnaissance of the Pluto system has revealed at high resolution the striking albedo contrasts from polar to equatorial latitudes on Pluto, as well as the sharpness of boundaries for longitudinal variations. These contrasts suggest that Pluto must undergo dynamic evolution that drives the redistribution of volatiles. Using the New Horizons results as a template, we explore the surface temperature variations driven seasonally on Pluto considering multiple timescales. These timescales include the current orbit (248 years) as well as the timescales for obliquity precession (peak-to-peak amplitude of 23° over 3 million years) and regression of the orbital longitude of perihelion (3.7 million years). These orbital variations create epochs of ;Extreme Seasons; where one pole receives a short, relatively warm summer and long winter, while the other receives a much longer, but less intense summer and short winter. We use thermal modeling to build upon the long-term insolation history model described by Earle and Binzel (2015) and investigate how these seasons couple with Pluto's albedo contrasts to create temperature effects. From this study we find that a bright region at the equator, once established, can become a site for net deposition. We see the region informally known as Sputnik Planitia as an example of this, and find it will be able to perpetuate itself as an ;always available; cold trap, thus having the potential to survive on million year or substantially longer timescales. Meanwhile darker, low-albedo, regions near the equator will remain relative warm and generally not attract volatile deposition. We argue that the equatorial region is a ;preservation zone; for whatever albedo is seeded there. This offers insight as to why the equatorial band of Pluto displays the planet's greatest albedo contrasts.

Re-examination of the Possibility of Haze in Pluto's Atmosphere Based on Multi-Wavelength Observations of the Pluto Occultation of P131.1.

NASA Astrophysics Data System (ADS)

Thomas-Osip, J. E.; Elliot, J. L.; Clancy, K. B.

2002-12-01

Multi-wavelength observations of the occultation of P131.1 by Pluto (see Elliot et al., this conference) allow for a re-examination of the possibility of the existence of haze in Pluto's atmosphere. Models of the extinction efficiency of haze particles as a function of wavelength are being used investigate the potential for the existence of haze in the 2002 Pluto atmosphere. The existence of a haze layer in Pluto's atmosphere was postulated to explain the abrupt change in slope seen in the light curve of the 1988 stellar occultation by Pluto (Elliot and Young 1992, AJ, 103, 991). An alternative explanation (Hubbard et al. 1990, Icarus, 84, 1) includes a steep thermal gradient near the surface instead of, or in addition to, a haze layer. Modeling of the growth and sedimentation of photo-chemically produced spherical aerosols (Stansberry et al. 1989, Geophys. Res. Let., 16, 1221) suggested that an appropriate production rate is not sufficient to produce the opacity necessary to account for change in slope found in the 1988 light curve, if it were due solely to spherical particle haze extinction. Recent studies (see for example, Rannou et al. 1995, Icarus, 188, 355 and Thomas-Osip et al. 2002, Icarus, submitted) have shown that it is likely that photochemical hazes on Titan are aggregate in nature. Fractal aggregate particles can have larger extinction efficiencies than equivalent mass spheres of the same material (Rannou et al. 1999, Planet. Space Sci., 47,385). We are, therefore, also re-examining the effect of a haze with an aggregate morphology on modeling of the 1988 occultation observations. This research has been supported in part by NSF Grant AST-0073447 and NASA Grant NAG5-10444.

The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation.

PubMed

Ortiz, J L; Santos-Sanz, P; Sicardy, B; Benedetti-Rossi, G; Bérard, D; Morales, N; Duffard, R; Braga-Ribas, F; Hopp, U; Ries, C; Nascimbeni, V; Marzari, F; Granata, V; Pál, A; Kiss, C; Pribulla, T; Komžík, R; Hornoch, K; Pravec, P; Bacci, P; Maestripieri, M; Nerli, L; Mazzei, L; Bachini, M; Martinelli, F; Succi, G; Ciabattari, F; Mikuz, H; Carbognani, A; Gaehrken, B; Mottola, S; Hellmich, S; Rommel, F L; Fernández-Valenzuela, E; Bagatin, A Campo; Cikota, S; Cikota, A; Lecacheux, J; Vieira-Martins, R; Camargo, J I B; Assafin, M; Colas, F; Behrend, R; Desmars, J; Meza, E; Alvarez-Candal, A; Beisker, W; Gomes-Junior, A R; Morgado, B E; Roques, F; Vachier, F; Berthier, J; Mueller, T G; Madiedo, J M; Unsalan, O; Sonbas, E; Karaman, N; Erece, O; Koseoglu, D T; Ozisik, T; Kalkan, S; Guney, Y; Niaei, M S; Satir, O; Yesilyaprak, C; Puskullu, C; Kabas, A; Demircan, O; Alikakos, J; Charmandaris, V; Leto, G; Ohlert, J; Christille, J M; Szakáts, R; Farkas, A Takácsné; Varga-Verebélyi, E; Marton, G; Marciniak, A; Bartczak, P; Santana-Ros, T; Butkiewicz-Bąk, M; Dudziński, G; Alí-Lagoa, V; Gazeas, K; Tzouganatos, L; Paschalis, N; Tsamis, V; Sánchez-Lavega, A; Pérez-Hoyos, S; Hueso, R; Guirado, J C; Peris, V; Iglesias-Marzoa, R

2017-10-11

Haumea-one of the four known trans-Neptunian dwarf planets-is a very elongated and rapidly rotating body. In contrast to other dwarf planets, its size, shape, albedo and density are not well constrained. The Centaur Chariklo was the first body other than a giant planet known to have a ring system, and the Centaur Chiron was later found to possess something similar to Chariklo's rings. Here we report observations from multiple Earth-based observatories of Haumea passing in front of a distant star (a multi-chord stellar occultation). Secondary events observed around the main body of Haumea are consistent with the presence of a ring with an opacity of 0.5, width of 70 kilometres and radius of about 2,287 kilometres. The ring is coplanar with both Haumea's equator and the orbit of its satellite Hi'iaka. The radius of the ring places it close to the 3:1 mean-motion resonance with Haumea's spin period-that is, Haumea rotates three times on its axis in the time that a ring particle completes one revolution. The occultation by the main body provides an instantaneous elliptical projected shape with axes of about 1,704 kilometres and 1,138 kilometres. Combined with rotational light curves, the occultation constrains the three-dimensional orientation of Haumea and its triaxial shape, which is inconsistent with a homogeneous body in hydrostatic equilibrium. Haumea's largest axis is at least 2,322 kilometres, larger than previously thought, implying an upper limit for its density of 1,885 kilograms per cubic metre and a geometric albedo of 0.51, both smaller than previous estimates. In addition, this estimate of the density of Haumea is closer to that of Pluto than are previous estimates, in line with expectations. No global nitrogen- or methane-dominated atmosphere was detected.

A Comparative Planetology Activity

ERIC Educational Resources Information Center

LoPresto, Michael C.; Murrell, Steven R.

2010-01-01

The beginning of a typical solar system "unit" in a traditional introductory astronomy course often consists of an overview of the different object types--planets, moons, and debris (asteroids, comets, and meteors), and now also Pluto's home, the Kuiper belt--prior to coverage of formation and more detail about the various object types. An…

What Happened to Pluto?

ERIC Educational Resources Information Center

Consolmagno, Guy

2007-01-01

I had just finished speaking at the Cranbrook Museum of Science outside Detroit, presenting an hour-long talk about the newly defined dwarf planets, which covered the history of the IAU, the discovery of transneptunian objects (TNOs), the essentials of planetary nomenclature, and was full of PowerPoint graphics and erudite astronomy. The questions…

Fourier spectroscopy in planetary research

NASA Technical Reports Server (NTRS)

Hanel, R. A.; Kunde, V. G.

1975-01-01

The application of Fourier Transform Spectroscopy (FTS) to planetary research is reviewed. The survey includes FTS observations of the sun, all the planets except Uranus and Pluto, The Galilean satellites and Saturn's rings. Instrumentation and scientific results are considered. The prospects and limitations of FTS for planetary research in the forthcoming years are discussed.

Geology Before Pluto: Pre-encounter Considerations

NASA Astrophysics Data System (ADS)

Moore, J. M.

2014-12-01

Pluto, its large satellite Charon, and its four small known satellites represent the first trans-Neptunian Kuiper Belt objects populating the outer-most solar system beyond the gas giant planets to be studied in detail from a spacecraft (New Horizons). A complete picture of the solar nebula and solar system formation cannot be confidently formulated until representatives of this group of bodies at the edge of solar space have been examined. The Pluto system is composed of unique, lunar- and intermediate-sized objects that can tell us much about how objects with volatile icy compositions evolve. Modeling of the interior suggests that geologic activity may have been significant to some degree, and observations of frost on the surface could imply the need for a geologic reservoir for the replenishment of these phases. However, these putative indicators of Pluto's geologic history are inconclusive and unspecific. Detailed examination of Pluto's geologic record is the only plausible means of bridging the gap between theory and observation. In this talk I will examine the potential importance of these tentative indications of geologic activity and how specific spacecraft observations have been designed and used to constrain the Pluto system's geologic history. The cameras of New Horizons will provide robust data sets that should be immanently amenable to geological analysis of the Pluto system's landscapes. In this talk, we begin with a brief discussion of the planned observations by the New Horizons cameras that will bear most directly on geological interpretability. Then I will broadly review major geological processes that could potentially operate on the surfaces of Pluto and its moons. I will first survey exogenic processes (i.e., those for which energy for surface modification is supplied externally to the planetary surface): impact cratering, sedimentary processes (including volatile migration), and the work of wind. I will conclude with an assessment of the prospects for endogenic activity in the form of tectonics and cryovolcanism.

Geology Before Pluto: Pre-encounter Considerations

NASA Astrophysics Data System (ADS)

Moore, Jeffrey

2014-05-01

Jeffrey M. Moore (NASA Ames) and the New Horizons Science Team Pluto, its large satellite Charon, and its four small known satellites represent the first trans-Neptunian Kuiper Belt objects populating the outer-most solar system beyond the gas giant planets to be studied in detail from a spacecraft (New Horizons). A complete picture of the solar nebula and solar system formation cannot be confidently formulated until representatives of this group of bodies at the edge of solar space have been examined. The Pluto system is composed of unique, lunar- and intermediate-sized objects that can tell us much about how objects with volatile icy compositions evolve. Modeling of the interior suggests that geologic activity may have been significant to some degree, and observations of frost on the surface could imply the need for a geologic reservoir for the replenishment of these phases. However, these putative indicators of Pluto's geologic history are inconclusive and unspecific. Detailed examination of Pluto's geologic record is the only plausible means of bridging the gap between theory and observation. In this talk I will examine the potential importance of these tentative indications of geologic activity and how specific spacecraft observations have been designed and used to constrain the Pluto system's geologic history. The cameras of New Horizons will provide robust data sets that should be immanently amenable to geological analysis of the Pluto System's landscapes. In this talk, we begin with a brief discussion of the planned observations by the New Horizons cameras that will bear most directly on geological interpretability. Then I will broadly review major geological processes that could potentially operate on the surfaces of Pluto and its moons. I will first survey exogenic processes (i.e. those for which energy for surface modification is supplied externally to the planetary surface): impact cratering, sedimentary processes (including volatile migration), and the work of wind. I will conclude with an assessment of the prospects for endogenic activity in the form of tectonics and cryo-volcanism.

Geology Before Pluto: Pre-Encounter Considerations

NASA Technical Reports Server (NTRS)

Moore, Jeffrey M.

2014-01-01

Pluto, its large satellite Charon, and its four known satellites represent the first trans-Neptunian Kuiper Belt objects populating the outer-most solar system beyond the gas giant planets to be studied in detail from a spacecraft (New Horizons). A complete picture of the solar nebula, and solar system formation cannot be confidently formulated until representatives of this group of bodies at the edge of solar space have been examined. The Pluto system is composed of unique lunar- and intermediate-sized objects that can tell us much about how objects with volatile icy compositions evolve. Modeling of the interior suggests that geologic activity may have been to some degree, and observations of frost on the surface could imply the need for a geologic reservoir for the replenishment of these phases. However, the putative indicators of Pluto's geologic history are inconclusive and unspecific. Detailed examination of Pluto's geologic record is the only plausible means of bridging the gap between theory and observations. In this talk I will examine the potential importance of these tentative indications of geologic activity and how specific spacecraft observations have been designed and used to constrain the Pluto system's geologic history. The cameras of New Horizons will provide robust data sets that should be immanently amenable to geological analysis of the Pluto System's landscapes. In this talk, we begin with a brief discussion of the planned observations by New Horizons' cameras that will bear most directly on geological interpretability. Then I will broadly review major geological processes that could potentially operate of the surfaces of Pluto and its moons. I will first survey exogenic processes (i.e., those for which energy for surface modification is supplied externally to the planetary surface): impact cratering, sedimentary processes (including volatile migration) and the work of wind. I will conclude with an assessment of prospects for endogenic activity in the form of tectonics and cryo-volcanism.

New Horizons Results at Charon

NASA Astrophysics Data System (ADS)

Buratti, B. J.; Stern, A.; Moore, J. M.; Weaver, H. A., Jr.; Grundy, W. M.; Hofgartner, J. D.; Spencer, J. R.; McKinnon, W. B.; Olkin, C.; Young, L. A.; Verbiscer, A.; Singer, K. N.; Robbins, S. J.; Ennico Smith, K.

2016-12-01

The New Horizons Spacecraft encountered dwarf planet Pluto and its system of moons on July 15, 2015 for the first detailed study of a Kuiper Belt Object (1). Pluto possesses a system of at least 5 moons, including Charon, which is the largest moon in relation to its primary, comprising 12% of the mass of Pluto. The results from the flyby show a world that has undergone a large resurfacing event on at least one of its hemispheres, perhaps from differentiation and subsequent freezing of a subsurface ocean. Charon has a complex system of faults, and regions of various ages based on crater counting statistics. It has no evidence for recent or ongoing geologic activity as Pluto does. Its visible geometric albedo is 0.41±0.02, with normal reflectances ranging from 0.2-0.7. A few isolated brighter areas exist. A northern polar cap of low-albedo red material may be formed from a newly discovered process in the Solar System: the capture of methane from Pluto's atmosphere and subsequent polymerization and accumulation of a complex lag deposit (2). Unlike Pluto, which has a surface covered primarily of methane and nitrogen, Charon's surface is composed of water ice, along with NH3-ice in some form (3). The substantial relief on the moon implies that ice extends below the surface. The bulk density of Pluto and Charon are similar (1). This result implies that if Charon was formed from an impact and reaccretion event involving Pluto and a second body (4), it is unlikely the two bodies were fully differentiated prior to the event. (1) Stern, S. A. et al. (2015). Science 350, 292. (2) Grundy, W. M. et al. (2016). Manuscript accepted at Nature. (3) Grundy, W. M. et al. (2016). Science 351, 1283. (4) Canup, R. M. (2011). Astron. J. 141, 35. Funded by NASA.

Observational Constraints on a Pluto Torus of Circumsolar Neutral Gas

NASA Astrophysics Data System (ADS)

Hill, M. E.; Kollmann, P.; McNutt, R. L., Jr.; Smith, H. T.; Bagenal, F.; Brown, L. E.; Elliott, H. A.; Haggerty, D. K.; Horanyi, M.; Krimigis, S. M.; Kusterer, M. B.; Lisse, C. M.; McComas, D. J.; Piquette, M. R.; Sidrow, E. J.; Strobel, D. F.; Szalay, J.; Vandegriff, J. D.; Zirnstein, E.; Ennico Smith, K.; Olkin, C.; Weaver, H. A., Jr.; Young, L. A.; Stern, S. A.

2015-12-01

We present the concept of a neutral gas torus surrounding the Sun, aligned with Pluto's orbit, and place observational constraints based primarily on comparison of New Horizons (NH) measurements with a 3-D Monte Carlo model adapted from analogous satellite tori surrounding Saturn and Jupiter. Such a torus, or perhaps partial torus, should result from neutral N2 escaping from Pluto's exosphere. Unlike other more massive planets closer to the Sun, neutrals escape Pluto readily owing, e.g., to the high thermal speed relative to the escape velocity. Importantly, escaped neutrals have a long lifetime due to the great distance from the Sun, ~100 years for photoionization of N2 and ~180 years for photoionization of N, which results from disassociated N2. Despite the lengthy 248-year orbit, these long e-folding lifetimes may allow an enhanced neutral population to form an extended gas cloud that modifies the N2 spatial profile near Pluto. These neutrals are not directly observable by NH but once ionized N2+ or N+ are picked up by the solar wind, reaching ~50 keV, making these pickup ions (PUIs) detectable by NH's Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument. PEPSSI observations analyzed to date may constrain the N2 density; the remaining ~95% of the encounter data, scheduled for downlink in August along with similarly anticipated data from the Solar Wind Around Pluto (SWAP) experiment, should help determine the Pluto outgassing rates. Measurements from SWAP include the solar wind speed, a quantity that greatly enhances PUI studies by enabling us to directly account for the PUI distribution's sensitive dependence on plasma speed. Note that anomalous cosmic ray Si observed at Voyager is overabundant by a factor of ~3000 relative to interstellar composition. This might be related to "outer source" PUIs, but the fact that N2 and Si are indistinguishable in many instruments could mean that N2 is actually driving this apparent Si discrepancy.

A Distant Solar System Artist Concept

NASA Image and Video Library

2004-12-09

This artist concept depicts a distant hypothetical solar system, similar in age to our own. Looking inward from the system outer fringes, a ring of dusty debris can be seen, and within it, planets circling a star the size of our Sun. This debris is all that remains of the planet-forming disk from which the planets evolved. Planets are formed when dusty material in a large disk surrounding a young star clumps together. Leftover material is eventually blown out by solar wind or pushed out by gravitational interactions with planets. Billions of years later, only an outer disk of debris remains. These outer debris disks are too faint to be imaged by visible-light telescopes. They are washed out by the glare of the Sun. However, NASA's Spitzer Space Telescope can detect their heat, or excess thermal emission, in infrared light. This allows astronomers to study the aftermath of planet building in distant solar systems like our own. http://photojournal.jpl.nasa.gov/catalog/PIA07096

KSC-05pd2648

NASA Image and Video Library

2005-12-07

KENNEDY SPACE CENTER, FLA. - A Florida quarter is prepared for installation on the New Horizons spacecraft in Kennedy Space Center's Payload Hazardous Servicing Facility. The new quarter, engraved with the "Gateway to Discovery" design, will accompany New Horizons on its 3-billion-mile journey to the planet Pluto and its moon, Charon. Although appropriate for the mission to carry the coin from the state that symbolizes space exploration, it will also serve a practical purpose: scientists are using the quarter as a spin-balance weight. New Horizons comprises seven scientific instruments that will characterize the global geology and geomorphology of Pluto and its moon Charon, map their surface compositions and temperatures, and examine Pluto's complex atmosphere. After that, flybys of Kuiper Belt objects from even farther in the solar system may be undertaken in an extended mission. New Horizons is the first mission in NASA's New Frontiers program of medium-class planetary missions. The spacecraft, designed for NASA by the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., will launch aboard a Lockheed Martin Atlas V rocket and fly by Pluto and Charon as early as summer 2015. Photo Credit: Applied Physics Laboratory/George W. Rogers III

The Whale and the Donut

NASA Image and Video Library

2015-07-07

This map of Pluto, created from images taken from June 27-July 3, 2015, by the Long Range Reconnaissance Imager (LORRI) on New Horizons, was combined with lower-resolution color data from the spacecraft's Ralph instrument. The center of the map corresponds to the side of Pluto that will be seen close-up during New Horizons' July 14 flyby. This map gives mission scientists an important tool to decipher the complex and intriguing pattern of bright and dark markings on Pluto's surface. Features from all sides of Pluto can now be seen at a glance and from a consistent perspective, making it much easier to compare their shapes and sizes. The elongated dark area informally known as "the whale," along the equator on the left side of the map, is one of the darkest regions visible to New Horizons. It measures some 1,860 miles (3,000 kilometers) in length. Directly to the right of the whale's "snout" is the brightest region visible on the planet, which is roughly 990 miles (1,600 kilometers) across. This may be a region where relatively fresh deposits of frost -- perhaps including frozen methane, nitrogen and/or carbon monoxide -- form a bright coating. http://photojournal.jpl.nasa.gov/catalog/PIA19700

(abstract) Follow-on Missions for the Pluto Spacecraft

NASA Technical Reports Server (NTRS)

Weinstein, Stacy; Salvo, Chris; Stern, Alan

1994-01-01

The Pluto Fast Flyby mission development baseline consists of 2 identical spacecraft (120 - 165 kg) to be launched to Pluto/Charon in the late 1990s. These spacecraft are intended to fly by Pluto and Charon in order to perform various remote-sensing scientific investigations and have a mission development cost less than $400M (FY92$) through launch plus 30 days. The long-life (6 - 10 years) mission duration and lightweight design make the Pluto spacecraft a good candidate for a number of other flyby missions to objects in the outer Solar System, and some of these were investigated by JPL in cooperation with NASA Code SL's (Solar System Exploration) Outer Planets Science Working Group (OPSWG) in 1993. The JPL team looked at what it would mean to fly one of these missions (if a third spacecraft were available) in terms of flight time, spacecraft modifications, and science payload resources; the OPSWG recommended science investigation modifications for the different targets based on the available resources. The missions could, in many cases, utilize less capable launch vehicles, thereby reducing life-cycle cost of the mission. Examples of the sort of targets which were investigated and looked attractive in terms of flight time are: Uranus, Neptune, Uranus/Neptune dual-mission, Trojan asteroids (624 Hektor, 617 Patroclus, others), 5145 Pholus (the reddest object known in the solar system), and Kuiper Belt objects (i.e., 1992 QB1) . This paper will present the results of this investigation in terms of potential science return, performance, and the potential for life-cycle cost reductions through inheritance from Pluto Fast Flyby .

The Light and Dark Sides of a Distant Planet

NASA Image and Video Library

2006-10-12

The top graph consists of infrared data from NASA Spitzer Space Telescope. It tells astronomers that a distant planet, called Upsilon Andromedae b, always has a giant hot spot on the side that faces the star, while the other side is cold and dark.

The Exploration of the Pluto System by New Horizons

NASA Astrophysics Data System (ADS)

Weaver, Harold; Stern, S. Alan

2016-07-01

The New Horizons (NH) mission was selected by NASA in November 2001 to conduct the first in situ reconnaissance of Pluto and the Kuiper belt. The NH spacecraft was launched on 2006 January 19, received a gravity assist from Jupiter during closest approach on 2007 February 28, and flew 12,500 km above Pluto's surface on 2015 July 14. NH carried a sophisticated suite of seven scientific instruments, altogether weighing less than 30 kg and drawing less than 30 W of power, that includes panchromatic and color imagers, ultraviolet and infrared spectral imagers, a radio science package, plasma and charged particle sensors, and a dust counting experiment. The NH flyby of the Pluto system executed flawlessly, providing unprecedented detail on the Pluto-Charon binary and Pluto's four small moons (Styx, Nix, Kerberos, and Hydra, in order of their orbital distance from Pluto). Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. NH discovered trace hydrocarbons in Pluto's atmosphere, multiple global haze layers, and a surface pressure near 10 microbars. Pluto's diverse surface geology and long term activity raise fundamental questions about how small planets remain active many billions of years (Gyr) after formation. Charon displays tectonics, evidence for a heterogeneous crustal composition, and a puzzling giant hood of dark material covering its North Pole. Crater density statistics for Charon's surface give a crater retention age of 4-4.5 Ga, indicating that Charon's geological evolution largely ceased early in its history. Nix and Hydra have high albedos suggestive of H2O-ice covered surfaces. Crater densities on Nix and Hydra indicate surface ages > 4 Ga. All the small satellites have highly elongated shapes and are rotating much faster then synchronous with their orbital periods, with rotational poles clustered near the Pluto-Charon orbital plane. The NH spacecraft remains healthy and was targeted toward the flyby of a small (~30-40 km diameter) KBO in late-2015, enabling the study of an object (2014 MU69) in a completely different dynamical class (cold classical) than Pluto, if NASA approves an Extended Mission phase. The proposed Extended Mission would also include observations of more than 20 other KBOs at resolutions and geometries not feasible from Earth, and studies of the heliospheric plasma, neutral H and He, and the dust environment out to 50 AU from the Sun.

First Official Pluto Feature Names

NASA Image and Video Library

2017-09-06

The International Astronomical Union (IAU), the internationally recognized authority for naming celestial bodies and their surface features, approved names of 14 surface features on Pluto in August 2017. The names were proposed by NASA's New Horizons team following the first reconnaissance of Pluto and its moons by the New Horizons spacecraft in 2015. The names, listed below, pay homage to the underworld mythology, pioneering space missions, historic pioneers who crossed new horizons in exploration, and scientists and engineers associated with Pluto and the Kuiper Belt. Tombaugh Regio honors Clyde Tombaugh (1906-1997), the U.S. astronomer who discovered Pluto in 1930 from Lowell Observatory in Arizona. Burney crater honors Venetia Burney (1918-2009), who as an 11-year-old schoolgirl suggested the name "Pluto" for Clyde Tombaugh's newly discovered planet. Later in life she taught mathematics and economics. Sputnik Planitia is a large plain named for Sputnik 1, the first space satellite, launched by the Soviet Union in 1957. Tenzing Montes and Hillary Montes are mountain ranges honoring Tenzing Norgay (1914-1986) and Sir Edmund Hillary (1919-2008), the Indian/Nepali Sherpa and New Zealand mountaineer were the first to reach the summit of Mount Everest and return safely. Al-Idrisi Montes honors Ash-Sharif al-Idrisi (1100-1165/66), a noted Arab mapmaker and geographer whose landmark work of medieval geography is sometimes translated as "The Pleasure of Him Who Longs to Cross the Horizons.” Djanggawul Fossae defines a network of long, narrow depressions named for the Djanggawuls, three ancestral beings in indigenous Australian mythology who traveled between the island of the dead and Australia, creating the landscape and filling it with vegetation. Sleipnir Fossa is named for the powerful, eight-legged horse of Norse mythology that carried the god Odin into the underworld. Virgil Fossae honors Virgil, one of the greatest Roman poets and Dante's fictional guide through hell and purgatory in the Divine Comedy. Adlivun Cavus is a deep depression named for Adlivun, the underworld in Inuit mythology. Hayabusa Terra is a large land mass saluting the Japanese spacecraft and mission (2003-2010) that performed the first asteroid sample return. Voyager Terra honors the pair of NASA spacecraft, launched in 1977, that performed the first "grand tour" of all four giant planets. The Voyager spacecraft are now probing the boundary between the Sun and interstellar space. Tartarus Dorsa is a ridge named for Tartarus, the deepest, darkest pit of the underworld in Greek mythology. Elliot crater recognizes James Elliot (1943-2011), an MIT researcher who pioneered the use of stellar occultations to study the solar system -- leading to discoveries such as the rings of Uranus and the first detection of Pluto's thin atmosphere. https://photojournal.jpl.nasa.gov/catalog/PIA21944

The Performance of Ultra-stable Oscillators for the Gravity Recovery and Interior Laboratory (GRAIL)

DTIC Science & Technology

2010-11-01

the mid-2000s for JHU/APL’s exploration mission of Pluto and the Kuiper belt . Fig. 1. Timeline of USO mission legacy with history of...determination at remote bodies far from Earth extends the possibility of measuring other moons, planets, and asteroids in future science mission concepts

Fourier spectroscopy and planetary research

NASA Technical Reports Server (NTRS)

Hanel, R. A.; Kunde, V. G.

1974-01-01

The application of Fourier Transform Spectroscopy (FTS) to planetary research is reviewed. The survey includes FTS observations of the sun, all the planets except Uranus and Pluto, the Galilean satellites and Saturn's rings. Instrumentation and scientific results are considered and the prospects and limitations of FTS for planetary research in the forthcoming years are discussed.

Voyager to Jupiter and Saturn

NASA Technical Reports Server (NTRS)

1977-01-01

The NASA Voyager mission to explore planets of the outer solar system is summarized. The mission schedule and profiles for encounters with Jupiter and Saturn, and possibly with Uranus and Pluto are included along with a description of the spacecraft and its trajectories. Scientific investigations to be made and the instruments carried are also discussed.

Formation of Pluto's moons: the fission hypothesis revisited

NASA Astrophysics Data System (ADS)

Prentice, A. J.

2015-12-01

I re-examine the fission hypothesis for the formation of Pluto's moons within the framework of a gas ring model for the origin of the solar system (Prentice 1978 Moon Planets 19 341; 2015 LPSC, abs. 2664). It is supposed that the planetary system condensed from a concentric family of orbiting gas rings. These were cast off by the proto-solar cloud (PSC) as a means for disposing of excess spin angular momentum during gravitational contraction. If contraction is homologous, the mean orbital radii R(n) (n = 0,1,2,3,..) of the rings form a nearly geometric sequence. The temperatures T(n) of the rings scale roughly as T(n) = A/R(n) and the gas pressures p(n) on the gas ring mean orbits scale as p(n) = B/R(n)^4. The constants A & B are chosen so that (1) the geometric mean of the ratio R(n+1)/R(n) of successive gas ring radii from Jupiter to Mercury matches the observed mean ratio of planetary distances and (2) that the metal mass fraction at Mercury's orbit, namely 0.70, yields a planet whose mean density equals the observed value (Prentice 2008, LPSC abs. 1945.pdf). I assume that proto-Pluto (PPO) condensed within the n = 0 gas ring shed by the PSC at the orbit of Quaoar (43.2 AU). Here T(0) = 26.3 K and p(0) = 1.3 x 10^(-9) bar. The condensate consists of anhydrous rock (mass fraction 0.5255), graphite (0.0163), water ice (0.1858), dry ice (0.2211), and methane ice (0.0513). The RTP rock density is 3.662 g/cc. I assume that melting of the ices in the PPO took place through the decay of short-lived radioactive nuclides, causing internal segregation of rock & graphite. If rotational fission did occur and Pluto's moons formed from ejected liquid water and CO2, we get a Charon mean density of 1.24 g/cc. This is much lower than the observed value. Perhaps some of the rock and graphite became entrained in the fissioned liquid, so yielding a dense core for Charon of mass fraction ~0.4? In any event, the surfaces of all of the moons should have initially been football-shaped, very smooth and consist solely of water ice. As there is no outward migration of the major planets in the gas ring model, the risk of impact bombardment is minimal. Most likely, subsequent tidal action between Pluto and Charon produced the chasms that girdle the equator of Charon (Barr & Collins 2015). I predict that New Horizons will detect dry ice in those parts of Hydra that have been gouged by impacts.

Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006

USGS Publications Warehouse

Seidelmann, P.K.; Archinal, B.A.; A'Hearn, M.F.; Conrad, A.; Consolmagno, G.J.; Hestroffer, D.; Hilton, J.L.; Krasinsky, G.A.; Neumann, G.; Oberst, J.; Stooke, P.; Tedesco, E.F.; Tholen, D.J.; Thomas, P.C.; Williams, I.P.

2007-01-01

Every three years the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report introduces improved values for the pole and rotation rate of Pluto, Charon, and Phoebe, the pole of Jupiter, the sizes and shapes of Saturn satellites and Charon, and the poles, rotation rates, and sizes of some minor planets and comets. A high precision realization for the pole and rotation rate of the Moon is provided. The expression for the Sun's rotation has been changed to be consistent with the planets and to account for light travel time ?? 2007 Springer Science+Business Media B.V.

Automated design of gravity-assist trajectories to Mars and the outer planets

NASA Technical Reports Server (NTRS)

Longuski, James M.; Williams, Steve N.

1991-01-01

In this paper, a new approach to planetary mission design is described which automates the search for gravity-assist trajectories. This method finds all conic solutions given a range of launch dates, a range of launch energies and a set of target planets. The new design tool is applied to the problems of finding multiple encounter trajectories to the outer planets and Venus gravity-assist trajectories to Mars. The last four-planet grand tour opportunity (until the year 2153) is identified. It requires an earth launch in 1996 and encounters Jupiter, Uranus, Neptune, and Pluto. Venus gravity-assist trajectories to Mars for the 30 year period 1995-2024 are examined. It is shown that in many cases these trajectories require less launch energy to reach Mars than direct ballistic trajectories.

The search for other planets: clues from the solar system.

PubMed

Owen, T

1994-01-01

Studies of element abundances and values of D/H in the atmospheres of the outer planets and Titan support a two-step model for the formation of these bodies. This model suggests that the dimensions of Uranus provide a good index for the sensitivity required to detect planets around other stars. The high proportion of N2 on the surfaces of Pluto and Triton indicates that this gas was the dominant reservoir of nitrogen in the early solar nebula. It should also be abundant on pristine comets. There is evidence that some of these comets may well have brought a large store of volatiles to the inner planets, while others were falling into the sun. In other systems, icy planetesimals falling into stars should reveal themselves through high values of D/H.

An unmanned probe to Pluto

NASA Technical Reports Server (NTRS)

1990-01-01

Now that Voyager II has completed its grand tour of the solar system, all the planets in the solar system, with the exception of Pluto, have been studied. Even now, missions to return to Mercury, Venus, Mars Jupiter, and Saturn are currently flying or are planned. However, a mission to explore Pluto is not, at the present time, being considered seriously. The design problem presented to the students was very general, i.e., design an unmanned mission to Pluto with a launch window constraint of the years 2000 to 2010. All other characteristics of the mission, such as mission type (flyby, orbiter, lander, penetrator), scientific objectives and payload, and the propulsion system were to be determined by the design teams. The design studies exposed several general problems to be solved. Due to the extreme distance to Pluto (and a corresponding travel time in the range of 10 to 25 years), the spacecraft had to be lighter and more robust than current spacecraft designs. In addition, advanced propulsion concepts had to be considered. These included the new generation of launch vehicles and upper stages and nuclear electric propulsion. The probe design offered an abundance of synthesis and analysis problems. These included sizing trade studies, selection of subsystem components, analysis of spacecraft dynamics, stability and control, structural design and material selection, trajectory design, and selection of scientific equipment. Since the characteristics of the mission, excluding the launch window, were to be determined by the design teams, the solutions varied widely.

Dust Ablation in Pluto's Atmosphere

NASA Astrophysics Data System (ADS)

Horanyi, M.; Poppe, A. R.; Sternovsky, Z.

2015-12-01

Based on measurements by in situ dust detectors onboard the Pioneer and New Horizon spacecraft the total production rate of dust particles born in the Kuiper belt can be estimated to be on the order of 5 x 10 ^3 kg/s in the approximate size range of 1 - 10 micron. These particles slowly migrate inward due to Poynting - Robertson drag and their spatial distribution is shaped by mean motion resonances with the gas giant planets in the outer solar system. The expected mass influx into Pluto's atmosphere is on the order of 50 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that, if the particles are rich in volatiles, they can fully sublimate due to drag heating and deposit their mass in a narrow layer. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles, as well as on our newly developed models of Pluto's atmosphere that can be learned by matching the altitude where haze layers could be formed.

Chiron and the Centaurs: Escapees from the Kuiper Belt

NASA Technical Reports Server (NTRS)

Stern, Alan; Campins, Humberto

1996-01-01

The outer Solar System has long appeared to be a largely empty place, inhabited only by the four giant planets, Pluto and a transient population of comets. In 1977 however, a faint and enigmatic object - 2060 Chiron - was discovered moving on a moderately inclined, strongly chaotic 51-year orbit which takes it from just inside Saturn's orbit out almost as far as that of Uranus. It was not initially clear from where Chiron originated. these objects become temporarily trapped on Centaur-like orbits Following Chiron's discovery, almost 15 years elapsed before other similar objects were discovered; five more have now been identified. Based on the detection statistics implied by these discoveries, it has become clear that these objects belong to a significant population of several hundred (or possibly several thousand) large icy bodies moving on relatively short-lived orbits between the giant planets. This new class of objects, known collectively as the Centaurs, are intermediate in diameter between typical comets (1-20 km) and small icy planets such as Pluto (approx. 2,300 km) and Triton (approx. 2,700 km). Although the Centaurs are interesting in their own right, they have taken on added significance following the recognition that they most probably originated in the ancient reservoir of comets and larger objects located beyond the orbit of Neptune known as the Kuiper belt.

The carbon budget in the outer solar nebula

NASA Technical Reports Server (NTRS)

Simonelli, Damon P.; Pollack, James B.; Mckay, Christopher P.; Reynolds, Ray T.; Summers, Audrey L.

1989-01-01

The compositional contrast between the giant-planet satellites and the significantly rockier Pluto/Charon system is indicative of different formation mechanisms; cosmic abundance calculations, in conjunction with an assumption of the Pluto/Charon system's direct formation from solar nebula condensates, strongly suggest that most of the carbon in the outer solar nebula was in CO form, in keeping with both the inheritance from the dense molecular clouds in the interstellar medium, and/or the Lewis and Prinn (1980) kinetic-inhibition model of solar nebula chemistry. Laboratory studies of carbonaceous chondrites and Comet Halley flyby studies suggest that condensed organic material, rather than elemental carbon, is the most likely candidate for the small percentage of the carbon-bearing solid in the outer solar nebula.

NOVA - Official Website | The Pluto Files

Science.gov Websites

December 14, 2011 on PBS Program Description (Program not available for streaming.) When the American : So that's when most people first learn about the planets. So his name comes up, and you learn he's a DEGRASSE TYSON (American Museum of Natural History, Hayden Planetarium): In 1930, a farm boy, with a

Chaotic Dynamics of Trans-Neptunian Objects Perturbed by Planet Nine

NASA Astrophysics Data System (ADS)

Hadden, Sam; Li, Gongjie; Payne, Matthew J.; Holman, Matthew J.

2018-06-01

Observations of clustering among the orbits of the most distant trans-Neptunian objects (TNOs) has inspired interest in the possibility of an undiscovered ninth planet lurking in the outskirts of the solar system. Numerical simulations by a number of authors have demonstrated that, with appropriate choices of planet mass and orbit, such a planet can maintain clustering in the orbital elements of the population of distant TNOs, similar to the observed sample. However, many aspects of the rich underlying dynamical processes induced by such a distant eccentric perturber have not been fully explored. We report the results of our investigation of the dynamics of coplanar test-particles that interact with a massive body on an circular orbit (Neptune) and a massive body on a more distant, highly eccentric orbit (the putative Planet Nine). We find that a detailed examination of our idealized simulations affords tremendous insight into the rich test-particle dynamics that are possible. In particular, we find that chaos and resonance overlap plays an important role in particles’ dynamical evolution. We develop a simple mapping model that allows us to understand, in detail, the web of overlapped mean-motion resonances explored by chaotically evolving particles. We also demonstrate that gravitational interactions with Neptune can have profound effects on the orbital evolution of particles. Our results serve as a starting point for a better understanding of the dynamical behavior observed in more complicated simulations that can be used to constrain the mass and orbit of Planet Nine.

Book Review: Distant wanderers / Copernicus Books/Springer , 2001/2002

NASA Astrophysics Data System (ADS)

Bhatt, H. C.

2002-06-01

Are we alone in the Universe? The Earth, teeming with life, as we know it, is only one amongst the nine planets (wanderers) that wander around the Sun in more or less circular orbits. Do distant stars also have planets circling them? Are some of them similar to Earth and support life? These questions have long occupied the human mind. However, until the closing years of the twentieth century, the idea that there are stars, other than the Sun, that have planets orbiting them, remained a subject of speculation and controversy because the astronomical observing techniques used for the detection of planetary companions of stars did not have the necessary precision. During the past several years, advances in technology and dedicated efforts of planet-hunting astronomers have made it possible to detect Jupiter-like or more massive planets around nearby stars. So far about 70 such extra-solar planets have been discovered indicating that our solar system is not unique and distant wanderers are not uncommon. Distant Wanderers narrates the story of the search for extra-solar planets, even as the search is becoming more vigorous with newer instruments pushing the limits of sensitivity that has often resulted in the detection of planetary systems with totally unexpected characteristics. The book is primarily aimed at non specialists, but practicing scientists, including astronomers, will find the narrative very interesting and sometimes offering a perspective that is unfamiliar to professionals. The book begins with an introduction to some basic astronomical facts about the Universe, evolution of stars, supernovae and formation of pulsars. The first extra-solar planets were discovered in 1992 around a radio pulsar (PSR 1257+12) by measuring the oscillatory perturbations in the pulse arrival times from the pulsar caused by the presence of orbiting earth-sized planets as their gravity forces the pulsar also to move in orbit around the system barycenter. Such planetary systems are, however, very rare and only one other planet around a pulsar has so far been found. The first extra-solar planet around a sun-like star was discovered in 1995 by M. Mayor and D. Queloz circling the star 51 Pegasi by the method of Doppler spectroscopy. Since then about 70 extra-solar planets have been discovered. Most of these have been detected by Doppler spectroscopy, but now newer methods like occultation and gravitational lensing have also begun to reveal extra-solar planets and candidate extra-solar planets. Distant Wanderers gives a brief description of current theories of planet formation in dusty disks around stars as they form by gravitational collapse of rotating interstellar clouds. Various techniques used by astronomers for the detection of extra-solar planets are discussed. Important astrophysical concepts relevant to planet formation and their detection are also explained. The reader is taken to observatories on mountain tops, laboratories where instruments are built and conferences where astronomers announce their discoveries, debate the results and discuss future strategies for the search for distant wanderers. The extra-solar planets discovered so far, around sun-like stars, are similar in mass to Jupiter or more massive. Their orbits show a great variety. Some are in very close orbits (orbital periods of a few days) about the parent star, and are therefore very hot (hot Jupiters), while others are in wider orbits and cold. Some have nearly circular orbits, while many of them have highly eccentric orbits. There are extra-solar planets with masses as large as about 10 times the mass of Jupiter, close to being brown dwarfs. The existence of such planetary systems was never predicted by the standard theories of planet and star formation. As the hunt for extra-solar planets continues with more sophisticated instruments using innovative ideas, astronomers can be sure to be rewarded with more surprises. In Distant Wanderers, these discoveries and technological developments, currently taking place and being planned for the future, in the search for extra-solar planets, are narrated by the author, Bruce Dorminey, in simple language and lucid style. There are a few technical errors in the book. For example, on page 4, the angular momentum , which must always be conserved, is said to be created. In the discussion of the proper motion (which is measured on the plane of the sky) of Barnard's star, on page 111, it is incorrect to say that the star is moving toward the Sun. The book is, otherwise, well written and succeeds in communicating the excitement of the hunt for the distant wanderers.

Space Education at the University of Texas at San Antonio: Army Space Cadre - Learn from Southwest Research Institute Scientists (Army Space Journal, 2009 Summer Edition)

DTIC Science & Technology

2009-01-01

Neptune and is similar to the asteroid belt , although it is far larger. Cassini studies the planet Saturn and its moons. The space- craft consists of two...and the Kuiper belt , beginning in 2015. The New Horizons spacecraft executed a fly-by of Jupiter in 2007. The Jupiter fly- by was used to provide a...gravitational assist that shaved years off the travel time to Pluto-Charon and the Kuiper belt . Charon is the largest moon of the dwarf planet

The New Cosmos

NASA Astrophysics Data System (ADS)

Eicher, David J.; Filippenko, Alex

2015-12-01

Foreword Alex Filippenko; 1. The awakening of astronomy; 2. How the Sun will die; 3. The end of life on Earth; 4. How the moon formed; 5. Where has all the water gone?; 6. Why did Venus turn inside-out?; 7. Is Pluto a planet?; 8. Planets everywhere; 9. The Milky Way as barred spiral; 10. Here comes Milkomeda; 11. The Big Bang's cosmic echo; 12. How large is the universe?; 13. The mystery of dark matter; 14. The bigger mystery of dark energy; 15. Black holes are ubiquitous; 16. What is the universe's fate?; 17. The meaning of life in the cosmos; Glossary; Bibliography; Index.

Portrait of Distant Planets

NASA Image and Video Library

2010-04-14

This image taken with the Palomar Observatory Hale Telescope, shows the light from three planets orbiting a star 120 light-years away. The planets star, called HR8799, is located at the spot marked with an X.

The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation

NASA Astrophysics Data System (ADS)

Ortiz, J. L.; Santos-Sanz, P.; Sicardy, B.; Benedetti-Rossi, G.; Bérard, D.; Morales, N.; Duffard, R.; Braga-Ribas, F.; Hopp, U.; Ries, C.; Nascimbeni, V.; Marzari, F.; Granata, V.; Pál, A.; Kiss, C.; Pribulla, T.; Komžík, R.; Hornoch, K.; Pravec, P.; Bacci, P.; Maestripieri, M.; Nerli, L.; Mazzei, L.; Bachini, M.; Martinelli, F.; Succi, G.; Ciabattari, F.; Mikuz, H.; Carbognani, A.; Gaehrken, B.; Mottola, S.; Hellmich, S.; Rommel, F. L.; Fernández-Valenzuela, E.; Campo Bagatin, A.; Cikota, S.; Cikota, A.; Lecacheux, J.; Vieira-Martins, R.; Camargo, J. I. B.; Assafin, M.; Colas, F.; Behrend, R.; Desmars, J.; Meza, E.; Alvarez-Candal, A.; Beisker, W.; Gomes-Junior, A. R.; Morgado, B. E.; Roques, F.; Vachier, F.; Berthier, J.; Mueller, T. G.; Madiedo, J. M.; Unsalan, O.; Sonbas, E.; Karaman, N.; Erece, O.; Koseoglu, D. T.; Ozisik, T.; Kalkan, S.; Guney, Y.; Niaei, M. S.; Satir, O.; Yesilyaprak, C.; Puskullu, C.; Kabas, A.; Demircan, O.; Alikakos, J.; Charmandaris, V.; Leto, G.; Ohlert, J.; Christille, J. M.; Szakáts, R.; Takácsné Farkas, A.; Varga-Verebélyi, E.; Marton, G.; Marciniak, A.; Bartczak, P.; Santana-Ros, T.; Butkiewicz-Bąk, M.; Dudziński, G.; Alí-Lagoa, V.; Gazeas, K.; Tzouganatos, L.; Paschalis, N.; Tsamis, V.; Sánchez-Lavega, A.; Pérez-Hoyos, S.; Hueso, R.; Guirado, J. C.; Peris, V.; Iglesias-Marzoa, R.

2017-10-01

Haumea—one of the four known trans-Neptunian dwarf planets—is a very elongated and rapidly rotating body. In contrast to other dwarf planets, its size, shape, albedo and density are not well constrained. The Centaur Chariklo was the first body other than a giant planet known to have a ring system, and the Centaur Chiron was later found to possess something similar to Chariklo’s rings. Here we report observations from multiple Earth-based observatories of Haumea passing in front of a distant star (a multi-chord stellar occultation). Secondary events observed around the main body of Haumea are consistent with the presence of a ring with an opacity of 0.5, width of 70 kilometres and radius of about 2,287 kilometres. The ring is coplanar with both Haumea’s equator and the orbit of its satellite Hi’iaka. The radius of the ring places it close to the 3:1 mean-motion resonance with Haumea’s spin period—that is, Haumea rotates three times on its axis in the time that a ring particle completes one revolution. The occultation by the main body provides an instantaneous elliptical projected shape with axes of about 1,704 kilometres and 1,138 kilometres. Combined with rotational light curves, the occultation constrains the three-dimensional orientation of Haumea and its triaxial shape, which is inconsistent with a homogeneous body in hydrostatic equilibrium. Haumea’s largest axis is at least 2,322 kilometres, larger than previously thought, implying an upper limit for its density of 1,885 kilograms per cubic metre and a geometric albedo of 0.51, both smaller than previous estimates. In addition, this estimate of the density of Haumea is closer to that of Pluto than are previous estimates, in line with expectations. No global nitrogen- or methane-dominated atmosphere was detected.

The Pluto system: Initial results from its exploration by New Horizons

NASA Astrophysics Data System (ADS)

Stern, S. A.; Bagenal, F.; Ennico, K.; Gladstone, G. R.; Grundy, W. M.; McKinnon, W. B.; Moore, J. M.; Olkin, C. B.; Spencer, J. R.; Weaver, H. A.; Young, L. A.; Andert, T.; Andrews, J.; Banks, M.; Bauer, B.; Bauman, J.; Barnouin, O. S.; Bedini, P.; Beisser, K.; Beyer, R. A.; Bhaskaran, S.; Binzel, R. P.; Birath, E.; Bird, M.; Bogan, D. J.; Bowman, A.; Bray, V. J.; Brozovic, M.; Bryan, C.; Buckley, M. R.; Buie, M. W.; Buratti, B. J.; Bushman, S. S.; Calloway, A.; Carcich, B.; Cheng, A. F.; Conard, S.; Conrad, C. A.; Cook, J. C.; Cruikshank, D. P.; Custodio, O. S.; Dalle Ore, C. M.; Deboy, C.; Dischner, Z. J. B.; Dumont, P.; Earle, A. M.; Elliott, H. A.; Ercol, J.; Ernst, C. M.; Finley, T.; Flanigan, S. H.; Fountain, G.; Freeze, M. J.; Greathouse, T.; Green, J. L.; Guo, Y.; Hahn, M.; Hamilton, D. P.; Hamilton, S. A.; Hanley, J.; Harch, A.; Hart, H. M.; Hersman, C. B.; Hill, A.; Hill, M. E.; Hinson, D. P.; Holdridge, M. E.; Horanyi, M.; Howard, A. D.; Howett, C. J. A.; Jackman, C.; Jacobson, R. A.; Jennings, D. E.; Kammer, J. A.; Kang, H. K.; Kaufmann, D. E.; Kollmann, P.; Krimigis, S. M.; Kusnierkiewicz, D.; Lauer, T. R.; Lee, J. E.; Lindstrom, K. L.; Linscott, I. R.; Lisse, C. M.; Lunsford, A. W.; Mallder, V. A.; Martin, N.; McComas, D. J.; McNutt, R. L.; Mehoke, D.; Mehoke, T.; Melin, E. D.; Mutchler, M.; Nelson, D.; Nimmo, F.; Nunez, J. I.; Ocampo, A.; Owen, W. M.; Paetzold, M.; Page, B.; Parker, A. H.; Parker, J. W.; Pelletier, F.; Peterson, J.; Pinkine, N.; Piquette, M.; Porter, S. B.; Protopapa, S.; Redfern, J.; Reitsema, H. J.; Reuter, D. C.; Roberts, J. H.; Robbins, S. J.; Rogers, G.; Rose, D.; Runyon, K.; Retherford, K. D.; Ryschkewitsch, M. G.; Schenk, P.; Schindhelm, E.; Sepan, B.; Showalter, M. R.; Singer, K. N.; Soluri, M.; Stanbridge, D.; Steffl, A. J.; Strobel, D. F.; Stryk, T.; Summers, M. E.; Szalay, J. R.; Tapley, M.; Taylor, A.; Taylor, H.; Throop, H. B.; Tsang, C. C. C.; Tyler, G. L.; Umurhan, O. M.; Verbiscer, A. J.; Versteeg, M. H.; Vincent, M.; Webbert, R.; Weidner, S.; Weigle, G. E.; White, O. L.; Whittenburg, K.; Williams, B. G.; Williams, K.; Williams, S.; Woods, W. W.; Zangari, A. M.; Zirnstein, E.

2015-10-01

The Pluto system was recently explored by NASA’s New Horizons spacecraft, making closest approach on 14 July 2015. Pluto’s surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto’s atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto’s diverse surface geology and long-term activity raise fundamental questions about how small planets remain active many billions of years after formation. Pluto’s large moon Charon displays tectonics and evidence for a heterogeneous crustal composition; its north pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected.

(abstract) A Low-Cost Mission to 2060 Chiron Based on the Pluto Fast Flyby

NASA Technical Reports Server (NTRS)

Stern, S. A.; Salvo, C. G.; Wallace, R. A.; Weinstein, S. S.; Weissman, P. R.

1994-01-01

The Pluto Fast Flyby-based mission to Chiron described in this paper is a low cost, scientifically rewarding, focused mission in the outer solar system. The proposed mission will make a flyby of 2060 Chiron, an active 'comet' with over 10(sup 4) times the mass of Halley, and an eccentric, Saturn-crossing orbit which ranges from 8.5 to 19 AU. This mission concept achieves the flyby 4.2 years after launch on a direct trajectory from Earth, is independent of Jupiter launch windows, and fits within Discovery cost guidelines. This mission offers the scientific opportunity to examine a class of object left unsampled by the trail-blazing Mariners, Pioneers, Voyagers, and missions to Halley. Spacecraft reconnaissance of Chiron addresses unique objectives relating to cometary science, other small bodies, the structure of quasi-bound atmospheres on modest-sized bodies, and the origin of primitive bodies and the giant planets. Owing to Chiron's large size (180

Properties of ultra low frequency upstream waves at Venus and Saturn: A comparison

NASA Technical Reports Server (NTRS)

Orlowski, D. S.; Russell, C. T.; Krauss-Varban, D.; Omidi, N.

1995-01-01

The upstream regions of all planets, except Pluto, have been investigated, using in situ spacecraft measurements and a variety of analysis techniques. The detailed studies at Earth indicate that these waves are generated locally in the magnetically connected solar wind by the interaction with ions backstreaming from the shock. However, since the properties of the solar wind vary with heliocentric distance and since properties of planetary shocks depend on plasma beta, interplanetary magnetic field (IMF) spiral angle and Mach number, the amount of heating, acceleration efficiencies, etc. significantly change with heliocentric distance. In turn the waves seen at each planet propagate not in the same but different (physical) propagation modes. In this paper we compare the ULF wave observations at an outer and an inner planet. We use the results of the ratio, quantites easily derivable with sufficient accuracy at each planet. We use the full electromagnetic dispersion relation for comparison with theoretical predictions.

Icy Dwarf Planets: Colored popsicles in the Solar System

NASA Astrophysics Data System (ADS)

Pinilla-Alonso, Noemi

2015-08-01

In 1992 the discovery of 1992 QB1 was the starting signal of a race to characterize the trans-Neptunian belt. The detection of icy “asteroids”, similar to Pluto, in the outer Solar System had been largely hypothesized but it had also being an elusive goal. This belt was considered by the planetary scientists as the icy promised land, the largest reservoir of primordial ices in the Solar System.From 1992 to 2005 about 1000 trans-Neptunian objects and Centaurs had been discovered and a lot of “first ever” science had been published: 1996 TO66, first ever detection of the water ice bands in a TNO's spectrum; 1998 WW31, first detection of a binary; first estimation of size and albedo from thermal and visible observations, Varuna; discovery of Sedna, at that moment “the coldest most distant place known in the Solar System”2005 was the year of the discovery of three large TNOs: (136108) Haumea, (136472) Makemake and (136199) Eris (a.k.a 2003 EL61, 2005 FY9 and 2003 UB313). These three big guys entered the schoolyard showing off as colored popsicles and making a clear statement: “We are special”, and sure they are!The discovery of these large TNOs resulted in 2006 in the adoption by the IAU of a new definition of planet and in the introduction of a new category of minor bodies: the “dwarf planets”. With only three members at this moment (although this can change anytime) the exclusive club of the icy dwarf planets is formed by the TNOs at the higher end of the size distribution. By virtue of their size and low surface temperatures, these bodies can retain most of their original inventory of ices. As a consequence, their visible and near-infrared spectra show evidences of water ice, nitrogen, methane and longer chains of hydrocarbons. Moreover, they have high geometric albedo in the visible. Also the accretional and radiogenic heating for these bodies was likely more than sufficient to have caused their internal differentiation.In this talk we will review the advance in the knowledge of the icy dwarf planets in the last 10 years and its cosmogonical meaning. We will also entertain the idea of the science that can be done in the next 10 years, on icy dwarf planets.

Water in Solar system

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.

2018-05-01

Water consists of two most common chemical elements in the universe: hydrogen and oxygen. At the study of the solar and other planetary systems, water was found on planets, their satellites, in cometary nuclei, in asteroids, dwarf planets such as Ceres and Pluto. Water also occurs in the giant molecular clouds at interstellar space, in the materials of protoplanetary disks, in the atmospheres of exoplanets. In addition, in liquid form, water can also be under the surface. Most of the satellites of the giant planets also contain a huge amount of water ice. Some satellites of Saturn and Jupiter even give evidence of the presence of oceans under their surface. These include, for example, Enceladus, Titan and Dione in Saturn; Europe, Ganymede and Callisto near Jupiter; Here we will also include the satellite of Neptune - Triton.

The evolution of a Pluto-like system during the migration of the ice giants

NASA Astrophysics Data System (ADS)

Pires, Pryscilla; Giuliatti Winter, Silvia M.; Gomes, Rodney S.

2015-01-01

The planetary migration of the Solar System giant planets in the framework of the Nice model (Tsiganis, K., Gomes, R., Morbidelli, A., Levison, H.F. [2005]. Nature 435,459-461; Morbidelli, A., Levison, H.F., Tsiganis, K., Gomes, R. [2005]. Nature 435, 462-465; Gomes, R., Levison, H.F., Tsiganis, K., Morbidelli, A. [2005]. Nature 435, 466-469) creates a dynamical mechanism which can be used to explain the distribution of objects currently observed in the Kuiper belt (e.g., Levison, H.F., Morbidelli, A., Vanlaerhoven, C., Gomes, R., Tsiganis, K. [2008]. Icarus 196, 258-273). Through this mechanism the planetesimals within the disk, heliocentric distance ranging from beyond Neptune's orbit to approximately 34 AU, are delivered to the belt after a temporary eccentric phase of Uranus and Neptune's orbits. We reproduced the mechanism proposed by Levison et al. to implant bodies into the Kuiper belt. The capture of Pluto into the external 3:2 mean motion resonance with Neptune is associated with this gravitational scattering model. We verified the existence of several close encounters between the ice giants and the planetesimals during their outward radial migration, then we believe that the analysis of the dynamical history of the plutonian satellites during this kind of migration is important, and would provide some constrains about their place of formation - within the primordial planetesimal disk or in situ. We performed N-body simulations and recorded the trajectories of the planetesimals during close approaches with Uranus and Neptune. Close encounters with Neptune are the most common, reaching approximately 1200 in total. A Pluto similarly sized body assumed the hyperbolic trajectories of the former primordial planetesimal with respect to those giant planets. We assumed the current mutual orbital configuration and sizes for Pluto's satellites, then we found that the rate of destruction of systems similar to that of Pluto with closest approaches to Uranus or Neptune <0.10 AU is 40%, i.e. these close approaches can lead to ejections of satellites or to changes in the satellites eccentricities at least 1 order of magnitude larger than the currently observed. However, we also found that the number of closest approaches which the minimum separation to Uranus or Neptune <0.10 AU is negligible, reaching 6%. In the other 60% of close encounter histories with closest approaches >0.10 AU, none of the systems have been destroyed. The latter sample concentrates 94% of closest approaches with the ice giants. Recall that throughout the early history of the Solar System giant impacts were common (McKinnon, W.B. [1989]. Astrophys. J. 344, L41-L44; Stern, A. [1991]. Icarus 90; Canup, R.M. [2005]. Science 307, 546-550). Also, impacts capable of forming a binary like Pluto-Charon can occur possibly prior to 0.5-1 Gyr (Kenyon, S.J., Bromley, B.C. [2014]. Astron. J. 147, 8), and small satellites such as Nix and Hydra can grow in debris from the giant impact (e.g., Canup, R.M. [2011]. Astron. J. 141, 35). Thus, we conclude that if Pluto and its satellites were emplaced into the KB from lower heliocentric orbits, then the Pluto system could survive the encounters that may have happened for emplacement of the Plutinos through the mechanism proposed by Levison et al.

Tholins as Coloring Agents on Pluto

NASA Astrophysics Data System (ADS)

Cruikshank, D. P.; Materese, C. K.; Imanaka, H.; Dalle Ore, C.; Sandford, S. A.; Nuevo, M.

2015-12-01

The shape of the reflectance spectrum of Pluto recorded with telescopes, 0.3-1.0 μm, shows the planet's yellow-red color (1). Additionally, multi-filter images of Pluto with the MVIC camera on the New Horizons spacecraft report concentrations of the coloring agent(s) in some regions of the surface, and apparent near absence in other regions. Tholins are refractory organic solids of complex structure and high molecular weight, with a wide range of color ranging from yellow and orange to dark red, and through tan to black. They are readily synthesized in the laboratory by energetic processing of mixtures of the ices (N2, CH4, CO) known on Pluto's surface (2), or the same molecules in the gas phase (3). Energy in the form of UV light, electrons, protons, or coronal discharge are all effective to one degree or another in producing various types of tholins; details of the composition and yield vary with experimental conditions. Chemical analysis of ice tholins shows carboxylic acids, urea, and HCN and other nitriles. Aromatic/olefinic, amide, and other functional groups are identified in XANES analysis (4). The ice tholins produce by e- irradiation have a higher concentration of N than UV ice tholins, with N/C ~0.9 (versus ~0.5 for UV tholins) and O/C~0.2. EUV photolysis of Pluto atmosphere analog yields pale yellow solids relatively transparent in the visual, and with aliphatic CH bonds prominent in IR spectra. This material may be responsible for Pluto's hazes (5). Various tholins are the principal coloring agents on Pluto's surface, probably Charon's colored region, and on numerous other outer Solar System bodies (6). Refs: 1. Cruikshank, D. P. et al. 2014 DPS abstract #419.04; 2. Cruikshank et al. 2015 Icarus 246, 82; 3. Krasnopolsky & Cruikshank 1999 JGR 104 E9, 21,979; 4. Materese, C. K. et al. 2014 Ap.J. 788:111, June 20; 5. Imanaka, H. et al. 2014 DPS abstract #419.10; 6. Cruikshank, D. P. et al. 2005 Adv. Space Res. 36, 178.

The Pluto fast flyby mission: Completing the reconnaissance of the solar system

NASA Technical Reports Server (NTRS)

Henry, Paul K.

1993-01-01

The concept of a fast flyby mission to Pluto has been advanced as a means to complete the reconnaissance of the known solar system. In order to acquire data on the Pluto system at the earliest possible time, and within the professional lifetime of investigators now active in the field, concepts are being developed for relatively small spacecraft in the mass range of 70 Kg to 350 Kg with flight times to Pluto of 7 to 13 years. Necessarily, the science complement on such a mission will be very mass and power limited. The challenge will be to define a spacecraft and an instrument package that will maximize the scientific return within these limitations. Cost, of course, will be a major consideration, and funds for new technology development specific to this mission will not be extensive. Consequently, innovative ways to incorporate elegant simplicity into the designs must be found. In order to facilitate exploration of the Pluto-Charon system, fully integrated science payloads must be developed. Two proposed mission designs involving limited mass and power science payloads have been presented to the Outer Planets Science Working Group (OPSWG). These payload mass allocations range from 5 to 30 kilograms with power allocations as low as 5 watts. The drivers behind these low mass and power allocations are that they enable developing missions to fit within the moderate mission cost profile and allow fast flight times to Pluto (7 to 13 years). The OPSWG has prioritized science goals for this class of reconnaissance mission. Three specific science objectives were identified as the highest priority required for the first Pluto mission. These goals were: (1) study of the neutral atmosphere, (2) geology and morphology, and (3) surface compositional mapping. In order to achieve these science goals within the constraints of low mass, power and cost, it may be necessary to combine the functions of 3 conventional instruments (CCD camera, Ultra-Violet Spectrometer, and Infrared Spectrometer) into one fully integrated payload. Where possible, this payload would share optics, mechanisms, electronics and packaging.

"A Planet of Confusion and Debate": Children's and Young People's Response to the News Coverage of Pluto's Loss of Planetary Status

ERIC Educational Resources Information Center

Jarman, Ruth; McClune, Billy

2009-01-01

Despite calls that the school science curriculum should develop among students an ability to understand and respond critically to science-related media reports, very little research has been directed toward an important matter relevant to that aim, namely, how children and young people, untutored, react to science in the news. This study sought,…

Astronomical studies of the major planets, natural satellites and asteroids using the 2.24 m telescope

NASA Technical Reports Server (NTRS)

Jefferies, J. T.

1982-01-01

Ground based detection of east-west asymmetries in the Jovian torus, three dimensional models of the plasma conditions in the Jovian torus, rotational variations in methane band images of Neptune, Io's rapid flickering, thermophysical models, the diameters and albedos of the satellites of Uranus from radiometric observations, the diameters of Pluto and Triton, standard stars are discussed.

Probing Signatures of a Distant Planet around the Young T-Tauri Star CI Tau Hosting a Possible Hot Jupiter

NASA Astrophysics Data System (ADS)

Konishi, Mihoko; Hashimoto, Jun; Hori, Yasunori

2018-06-01

We search for signatures of a distant planet around the two million-year-old classical T-Tauri star CI Tau hosting a hot-Jupiter candidate ({M}{{p}}\\sin i∼ 8.1 {M}Jupiter}) in an eccentric orbit (e ∼ 0.3). To probe the existence of an outer perturber, we reanalyzed 1.3 mm dust continuum observations of the protoplanetary disk around CI Tau obtained by the Atacama Large Millimeter/submillimeter Array (ALMA). We found a gap structure at ∼0.″8 in CI Tau’s disk. Our visibility fitting assuming an axisymmetric surface brightness profile suggested that the gap is located at a deprojected radius of 104.5 ± 1.6 au and has a width of 36.9 ± 2.9 au. The brightness temperature around the gap was calculated to be ∼2.3 K lower than that of the ambient disk. Gap-opening mechanisms such as secular gravitational instability (GI) and dust trapping can explain the gap morphology in the CI Tau disk. The scenario that an unseen planet created the observed gap structure cannot be ruled out, although the coexistence of an eccentric hot Jupiter and a distant planet around the young CI Tau would be challenging for gravitational scattering scenarios. The mass of the planet was estimated to be between ∼0.25 M Jupiter and ∼0.8 M Jupiter from the gap width and depth ({0.41}-0.06+0.04) in the modeled surface brightness image, which is lower than the current detection limits of high-contrast direct imaging. The young classical T-Tauri CI Tau may be a unique system for exploring the existence of a potential distant planet as well as the origin of an eccentric hot Jupiter.

First Ever High Resolution View of Pluto's Surface

NASA Image and Video Library

2017-12-08

New close-up images of a region near Pluto’s equator reveal a giant surprise: a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body. The mountains likely formed no more than 100 million years ago -- mere youngsters relative to the 4.56-billion-year age of the solar system -- and may still be in the process of building, says Jeff Moore of New Horizons’ Geology, Geophysics and Imaging Team (GGI). That suggests the close-up region, which covers less than one percent of Pluto’s surface, may still be geologically active today. Moore and his colleagues base the youthful age estimate on the lack of craters in this scene. Like the rest of Pluto, this region would presumably have been pummeled by space debris for billions of years and would have once been heavily cratered -- unless recent activity had given the region a facelift, erasing those pockmarks. “This is one of the youngest surfaces we’ve ever seen in the solar system,” says Moore. Unlike the icy moons of giant planets, Pluto cannot be heated by gravitational interactions with a much larger planetary body. Some other process must be generating the mountainous landscape. “This may cause us to rethink what powers geological activity on many other icy worlds,” says GGI deputy team leader John Spencer of the Southwest Research Institute in Boulder, Colo. The mountains are probably composed of Pluto’s water-ice “bedrock.” Although methane and nitrogen ice covers much of the surface of Pluto, these materials are not strong enough to build the mountains. Instead, a stiffer material, most likely water-ice, created the peaks. “At Pluto’s temperatures, water-ice behaves more like rock,” said deputy GGI lead Bill McKinnon of Washington University, St. Louis. The close-up image was taken about 1.5 hours before New Horizons closest approach to Pluto, when the craft was 478,000 miles (770,000 kilometers) from the surface of the planet. The image easily resolves structures smaller than a mile across. Image Credit: NASA-JHUAPL-SwRI NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Compositional Remote Sensing of Icy Planets and Satellites Beyond Jupiter

NASA Technical Reports Server (NTRS)

Roush, T. L.

2002-01-01

The peak of the solar energy distribution occurs at visual wavelengths and falls off rapidly in the infrared. This fact, improvements in infrared detector technology, and the low surface temperatures for most icy objects in the outer solar system have resulted in the bulk of telescopic and spacecraft observations being performed at visual and near-infrared wavelengths. Such observations, begun in the early 1970's and continuing to present, have provided compositional information regarding the surfaces of the satellites of Saturn and Uranus, Neptune's moon Triton, Pluto, Pluto's moon Charon, Centaur objects, and Kuiper belt objects. Because the incident sunlight penetrates the surface and interacts with the materials present there, the measured reflected sunlight contains information regarding the surface materials, and the ratio of the reflected to incident sunlight provides a mechanism of identifying the materials that are present.

The cable catapult - Putting it there and keeping it there

NASA Technical Reports Server (NTRS)

Forward, Robert L.; Conley, Buford R.; Stanek, Clay; Ramsey, William

1992-01-01

The cable catapult is the previously proposed method of using long space tethers for high speed interplanetary transport. A long conductive multistrand cable would be connected to a power supply and pointed in the desired direction. A linear motor would pull itself along the powered cable strands and launch a payload capsule toward a distant planet, where it would be caught and decelerated by another cable catapult positioned there. In this paper it is shown how cable catapults can be used to transport themselves to a distant planet and keep themselves in position near the planet despite the tendency of the payload capsule momentum transfer to push them apart.

The cable catapult - Putting it there and keeping it there

NASA Astrophysics Data System (ADS)

Forward, Robert L.; Conley, Buford R.; Stanek, Clay; Ramsey, William

1992-07-01

The cable catapult is the previously proposed method of using long space tethers for high speed interplanetary transport. A long conductive multistrand cable would be connected to a power supply and pointed in the desired direction. A linear motor would pull itself along the powered cable strands and launch a payload capsule toward a distant planet, where it would be caught and decelerated by another cable catapult positioned there. In this paper it is shown how cable catapults can be used to transport themselves to a distant planet and keep themselves in position near the planet despite the tendency of the payload capsule momentum transfer to push them apart.

Kepler-186f, the First Earth-size Planet in the Habitable Zone Artist Concept

NASA Image and Video Library

2014-04-17

This artist concept depicts Kepler-186f, the first validated Earth-size planet to orbit a distant star in the habitable zone, a range of distance from a star where liquid water might pool on the planet surface.

ORBITAL DISTRIBUTIONS OF CLOSE-IN PLANETS AND DISTANT PLANETS FORMED BY SCATTERING AND DYNAMICAL TIDES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagasawa, M.; Ida, S., E-mail: nagasawa.m.ad@m.titech.ac.jp

2011-12-01

We investigated the formation of close-in planets (hot Jupiters) by a combination of mutual scattering, Kozai effect, and tidal circularization, through N-body simulations of three gas giant planets, and compared the results with discovered close-in planets. We found that in about 350 cases out of 1200 runs ({approx}30%), the eccentricity of one of the planets is excited highly enough for tidal circularization by mutual close scatterings followed by secular effects due to outer planets, such as the Kozai mechanism, and the planet becomes a close-in planet through the damping of eccentricity and semimajor axis. The formation probability of close-in planetsmore » by such scattering is not affected significantly by the effect of the general relativity and inclusion of inertial modes in addition to fundamental modes in the tides. Detailed orbital distributions of the formed close-in planets and their counterpart distant planets in our simulations were compared with observational data. We focused on the possibility for close-in planets to retain non-negligible eccentricities ({approx}> 0.1) on timescales of {approx}10{sup 9} yr and have high inclinations, because close-in planets in eccentric or highly inclined orbits have recently been discovered. In our simulations we found that as many as 29% of the close-in planets have retrograde orbits, and the retrograde planets tend to have small eccentricities. On the other hand, eccentric close-in planets tend to have orbits of small inclinations.« less

OBSERVATIONAL SIGNATURES OF A MASSIVE DISTANT PLANET ON THE SCATTERING DISK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lawler, S. M.; Kavelaars, J. J.; Shankman, C.

The orbital element distribution of trans-Neptunian objects (TNOs) with large pericenters has been suggested to be influenced by the presence of an undetected, large planet at >200 au from the Sun. To find additional observables caused by this scenario, we present here the first detailed emplacement simulation in the presence of a massive ninth planet on the distant Kuiper Belt. We perform 4 Gyr N -body simulations with the currently known solar system planetary architecture, plus a 10  M {sub ⊕} planet with similar orbital parameters to those suggested by Trujillo and Sheppard or Batygin and Brown, and 10{sup 5} testmore » particles in an initial planetesimal disk. We find that including a distant super-Earth-mass planet produces a substantially different orbital distribution for the scattering and detached TNOs, raising the pericenters and inclinations of moderate semimajor axis (50 <  a  < 500 au) objects. We test whether this signature is detectable via a simulator with the observational characteristics of four precisely characterized TNO surveys. We find that the qualitatively very distinct solar system models that include a ninth planet are essentially observationally indistinguishable from an outer solar system produced solely by the four giant planets. We also find that the mass of the Kuiper Belt’s current scattering and detached populations is required to be 3–10 times larger in the presence of an additional planet. We do not find any evidence for clustering of orbital angles in our simulated TNO population. Wide-field, deep surveys targeting inclined high-pericenter objects will be required to distinguish between these different scenarios.« less

Retrieval of Haze Properties in Pluto's Atmosphere from New Horizons Observations

NASA Astrophysics Data System (ADS)

Fan, S.; Gao, P.; Yung, Y. L.

2017-12-01

On July 14th, 2015, New Horizons performed its historic close approach of Pluto, giving humanity unprecedented observations of the dwarf planet's atmosphere. One of the amazing features seen was the multi-layered haze in its atmosphere. The haze was detected both at visible wavelengths by the Long Range Reconnaissance Imager (LORRI) from direct imaging and in the ultraviolet by the Alice spectrograph from solar occultations. Preliminary analysis using simplified models showed that neither spherical nor 2-dimensional aggregate particles could satisfy both sets of observations. In this work, we present a joint retrieval of haze particles using both LORRI and Alice data, which examines various size distributions and dimensions of aggregate particles. We map out the haze particles' phase function by the forward scattering and extinction properties by the occultation. With the combination of these two approaches, the Haze's properties of size and shape are constrained.

A NEW HYBRID N-BODY-COAGULATION CODE FOR THE FORMATION OF GAS GIANT PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bromley, Benjamin C.; Kenyon, Scott J., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu

2011-04-20

We describe an updated version of our hybrid N-body-coagulation code for planet formation. In addition to the features of our 2006-2008 code, our treatment now includes algorithms for the one-dimensional evolution of the viscous disk, the accretion of small particles in planetary atmospheres, gas accretion onto massive cores, and the response of N-bodies to the gravitational potential of the gaseous disk and the swarm of planetesimals. To validate the N-body portion of the algorithm, we use a battery of tests in planetary dynamics. As a first application of the complete code, we consider the evolution of Pluto-mass planetesimals in amore » swarm of 0.1-1 cm pebbles. In a typical evolution time of 1-3 Myr, our calculations transform 0.01-0.1 M{sub sun} disks of gas and dust into planetary systems containing super-Earths, Saturns, and Jupiters. Low-mass planets form more often than massive planets; disks with smaller {alpha} form more massive planets than disks with larger {alpha}. For Jupiter-mass planets, masses of solid cores are 10-100 M{sub +}.« less

Our Solar System

NASA Astrophysics Data System (ADS)

Coates, Andrew

2005-10-01

Up until the dark ages, humankind knew of six planets including our own. The invention of the telescope, and the beginnings of scientific thought on orbits and planetary motion, were in the seventeenth century. The next three centuries added Uranus, Neptune and Pluto to the known list as well as the many moons, asteroids and comets that we know today. It is only in the latter part of the 20th century that we have been privileged to carry out in-situ exploration of the planets, comets and the solar wind's realm and to begin to understand the special conditions on Earth which meant that life started here. This is leading to a detailed view of the processes which have shaped our solar system. Here, we briefly review our current knowledge of the solar system we inhabit. We discuss the current picture of how the solar system began. Important processes at work, such as collisions and volcanism, and atmospheric evolution, are discussed. The planets, comets and asteroids are all discussed in general terms, together with the important discoveries from space missions which have led to our current views. For each of the bodies we present the current understanding of the physical properties and interrelationships and present questions for further study. The significance of recent results, such as proof that there were one standing bodies of water on Mars, and the discovery of what appears to be an Oort cloud comet, are put into context. What is in store for planetary exploration and discoveries in the future? Already a sequence of Mars exploration missions, a landing on a comet, further exploration of Saturn and the Jovian system and the first flyby of Pluto are planned. We examine the major scientific questions to be answered. We also discuss the prospects for finding other Earth-like planets elsewhere, and for finding extraterrestrial life both within and beyond our own solar system.

Voyager's Grand Tour

NASA Technical Reports Server (NTRS)

Uri, Joihn J.

2017-01-01

In the early days of the Space Age, scientists realized that given the right planetary alignments it might be possible to use the gravity of one planet to change the trajectory of a spacecraft and send it on to another planet without expending any fuel. This slingshot or gravity assist trajectory principle was first tested by Mariner 10, which used the gravity of Venus to slingshot its way to Mercury in 1974. A very rare planetary alignment would occur in the late 1970's allowing a spacecraft to visit all the outer planets (Jupiter, Saturn, Uranus, Neptune and Pluto) using gravity assists at each planet to send it on to the next. This unique alignment would not occur again for another 175 years! The initial ambitious plan, called the Grand Tour, was to send two pairs of spacecraft, one pair to visit Jupiter, Saturn and Pluto, the other to fly by Jupiter, Uranus and Neptune. However, the original plan was scaled back in the budget conscious early 1970's to just two less capable spacecraft visiting only Jupiter and Saturn, and Titan, Saturn's largest moon Taking advantage of this alignment would be two Voyager spacecraft, both beginning their long journeys in 1977. Voyager 2 launched first, on August 20, followed by Voyager 1 on September 5. Both spacecraft would first fly by Jupiter and use that planet's massive gravity to bend their trajectories to then fly by Saturn. Voyager 1 would also be targeted to fly by Saturn's moon Titan, which was known to have a dense atmosphere, a trajectory that would preclude any future planetary flybys. But the option was kept open, if Voyager 1's Titan flyby was successful, to retarget Voyager 2 to send it on to Uranus and maybe even Neptune - assuming it would survive that long! Just 13 days after its launch, Voyager 1 scored the first of its many firsts: at a distance of 7.25 million miles, it turned its camera back toward Earth and snapped the first ever photograph of the Earth-Moon system in a single frame, giving a sneak preview of the discoveries that lay ahead.

On the Existence of Regular and Irregular Outer Moons Orbiting the Pluto-Charon System

NASA Astrophysics Data System (ADS)

Michaely, Erez; Perets, Hagai B.; Grishin, Evgeni

2017-02-01

The dwarf planet Pluto is known to host an extended system of five co-planar satellites. Previous studies have explored the formation and evolution of the system in isolation, neglecting perturbative effects by the Sun. Here we show that secular evolution due to the Sun can strongly affect the evolution of outer satellites and rings in the system, if such exist. Although precession due to extended gravitational potential from the inner Pluto-Charon binary quench such secular evolution up to a crit ˜ 0.0035 au (˜0.09 R Hill the Hill radius; including all of the currently known satellites), outer orbits can be significantly altered. In particular, we find that co-planar rings and satellites should not exist beyond a crit; rather, satellites and dust particles in these regions secularly evolve on timescales ranging between 104 and 106 years, and quasi-periodically change their inclinations and eccentricities through secular evolution (Lidov-Kozai oscillations). Such oscillations can lead to high inclinations and eccentricities, constraining the range where such satellites (and dust particles) can exist without crossing the orbits of the inner satellites or crossing the outer Hill stability range. Outer satellites, if such exist are therefore likely to be irregular satellites, with orbits limited to be non-circular and/or highly inclined. Current observations, including the recent data from the New-Horizons mission explored only inner regions (<0.0012 au) and excluded the existence of additional satellites; however, the irregular satellites discussed here should reside farther, in the yet uncharted regions around Pluto.

The Origin of Pluto's Orbit: Implications for the Solar System Beyond Neptune

NASA Technical Reports Server (NTRS)

Malhotra, Renu

1995-01-01

The origin of the highly eccentric, inclined, and resonance-locked orbit of Pluto has long been a puzzle. A possible explanation has been proposed recently which suggests that these extraordinary orbital properties may be a natural consequence of the formation and early dynamical evolution of the outer solar system. A resonance capture mechanism is possible during the clearing of the residual planetesimal debris and the formation of the Oort Cloud of comets by planetesimal mass loss from the vicinity of the giant planets. If this mechanism were in operation during the early history of the planetary system, the entire region between the orbit of Neptune and approximately 50 AU would have been swept by first-order mean motion resonances. Thus, resonance capture could occur not only for Pluto, but quite generally for other trans-Neptunian small bodies. Some consequences of this evolution for the present-day dynamical structure of the trans-Neptunian region are (1) most of the objects in the region beyond Neptune and up to approximately 50 AU exist in very narrow zones located at orbital resonances with Neptune (particularly the 3:2 and the 2:1 resonances); and (2) these resonant objects would have significantly large eccentricities. The distribution of objects in the Kuiper Belt as predicted by this theory is presented here.

Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigour

NASA Astrophysics Data System (ADS)

McKinnon, William B.; Nimmo, Francis; Wong, Teresa; Schenk, Paul M.; White, Oliver L.; Roberts, J. H.; Moore, J. M.; Spencer, J. R.; Howard, A. D.; Umurhan, O. M.; Stern, S. A.; Weaver, H. A.; Olkin, C. B.; Young, L. A.; Smith, K. E.; Moore, J. M.; McKinnon, W. B.; Spencer, J. R.; Beyer, R.; Buie, M.; Buratti, B.; Cheng, A.; Cruikshank, D.; Dalle Ore, C.; Gladstone, R.; Grundy, W.; Howard, A.; Lauer, T.; Linscott, I.; Nimmo, F.; Olkin, C.; Parker, J.; Porter, S.; Reitsema, H.; Reuter, D.; Roberts, J. H.; Robbins, S.; Schenk, P. M.; Showalter, M.; Singer, K.; Strobel, D.; Summers, M.; Tyler, L.; Weaver, H.; White, O. L.; Umurhan, O. M.; Banks, M.; Barnouin, O.; Bray, V.; Carcich, B.; Chaikin, A.; Chavez, C.; Conrad, C.; Hamilton, D.; Howett, C.; Hofgartner, J.; Kammer, J.; Lisse, C.; Marcotte, A.; Parker, A.; Retherford, K.; Saina, M.; Runyon, K.; Schindhelm, E.; Stansberry, J.; Steffl, A.; Stryk, T.; Throop, H.; Tsang, C.; Verbiscer, A.; Winters, H.; Zangari, A.; New Horizons Geology, Geophysics and Imaging Theme Team

2016-06-01

The vast, deep, volatile-ice-filled basin informally named Sputnik Planum is central to Pluto's vigorous geological activity. Composed of molecular nitrogen, methane, and carbon monoxide ices, but dominated by nitrogen ice, this layer is organized into cells or polygons, typically about 10 to 40 kilometres across, that resemble the surface manifestation of solid-state convection. Here we report, on the basis of available rheological measurements, that solid layers of nitrogen ice with a thickness in excess of about one kilometre should undergo convection for estimated present-day heat-flow conditions on Pluto. More importantly, we show numerically that convective overturn in a several-kilometre-thick layer of solid nitrogen can explain the great lateral width of the cells. The temperature dependence of nitrogen-ice viscosity implies that the ice layer convects in the so-called sluggish lid regime, a unique convective mode not previously definitively observed in the Solar System. Average surface horizontal velocities of a few centimetres a year imply surface transport or renewal times of about 500,000 years, well under the ten-million-year upper-limit crater retention age for Sputnik Planum. Similar convective surface renewal may also occur on other dwarf planets in the Kuiper belt, which may help to explain the high albedos shown by some of these bodies.

Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigour.

PubMed

McKinnon, William B; Nimmo, Francis; Wong, Teresa; Schenk, Paul M; White, Oliver L; Roberts, J H; Moore, J M; Spencer, J R; Howard, A D; Umurhan, O M; Stern, S A; Weaver, H A; Olkin, C B; Young, L A; Smith, K E

2016-06-02

The vast, deep, volatile-ice-filled basin informally named Sputnik Planum is central to Pluto's vigorous geological activity. Composed of molecular nitrogen, methane, and carbon monoxide ices, but dominated by nitrogen ice, this layer is organized into cells or polygons, typically about 10 to 40 kilometres across, that resemble the surface manifestation of solid-state convection. Here we report, on the basis of available rheological measurements, that solid layers of nitrogen ice with a thickness in excess of about one kilometre should undergo convection for estimated present-day heat-flow conditions on Pluto. More importantly, we show numerically that convective overturn in a several-kilometre-thick layer of solid nitrogen can explain the great lateral width of the cells. The temperature dependence of nitrogen-ice viscosity implies that the ice layer convects in the so-called sluggish lid regime, a unique convective mode not previously definitively observed in the Solar System. Average surface horizontal velocities of a few centimetres a year imply surface transport or renewal times of about 500,000 years, well under the ten-million-year upper-limit crater retention age for Sputnik Planum. Similar convective surface renewal may also occur on other dwarf planets in the Kuiper belt, which may help to explain the high albedos shown by some of these bodies.

OPUS - Outer Planets Unified Search with Enhanced Surface Geometry Parameters - Not Just for Rings

NASA Astrophysics Data System (ADS)

Gordon, Mitchell; Showalter, Mark Robert; Ballard, Lisa; Tiscareno, Matthew S.; Heather, Neil

2016-10-01

In recent years, with the massive influx of data into the PDS from a wide array of missions and instruments, finding the precise data you need has been an ongoing challenge. For remote sensing data obtained from Jupiter to Pluto, that challenge is being addressed by the Outer Planets Unified Search, more commonly known as OPUS.OPUS is a powerful search tool available at the PDS Ring-Moon Systems Node (RMS) - formerly the PDS Rings Node. While OPUS was originally designed with ring data in mind, its capabilities have been extended to include all of the targets within an instrument's field of view. OPUS provides preview images of search results, and produces a zip file for easy download of selected products, including a table of user specified metadata. For Cassini ISS and Voyager ISS we have generated and include calibrated versions of every image.Currently OPUS supports data returned by Cassini ISS, UVIS, VIMS, and CIRS (Saturn data through June 2010), New Horizons Jupiter LORRI, Galileo SSI, Voyager ISS and IRIS, and Hubble (ACS, WFC3 and WFPC2).At the RMS Node, we have developed and incorporated into OPUS detailed geometric metadata, based on the most recent SPICE kernels, for all of the bodies in the Cassini Saturn observations. This extensive set of geometric metadata is unique to the RMS Node and enables search constraints such as latitudes and longitudes (Saturn, Titan, and icy satellites), viewing and illumination geometry (phase, incidence and emission angles), and distances and resolution.Our near term plans include adding the full set of Cassini CIRS Saturn data (with enhanced geometry), New Horizons MVIC Jupiter encounter images, New Horizons LORRI and MVIC Pluto data, HST STIS observations, and Cassini and Voyager ring occultations. We also plan to develop enhanced geometric metadata for the New Horizons LORRI and MVIC instruments for both the Jupiter and the Pluto encounters.OPUS: http://pds-rings.seti.org/search/

Monsters in the sky. I mostri del cielo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maffei, P.

1980-01-01

The book treats astronomical objects and phenomena which remain unexplained or unproven by current investigators. Specific objects discussed include comets, satellite clouds surrounding the earth, tektites, the planet Vulcan (within the orbit of Mercury), Planet X (beyond Pluto), the Gum Nebula, planetary nebulae, supernovae, supernova remnants, transient X-ray sources, the possible extinction of the dinosaurs by an X-ray explosion and super-supernovae. Attention is also given to the star Eta Carinae, black holes, BL Lacertae objects, active galaxies, Markarian galaxies, N and compact galaxies, Seyfert galaxies, quasars, redshift anomalies, Stephan's quintet of galaxies, and intergalactic black holes or black dwarfs whichmore » may account for the mass necessary to bind together clusters of galaxies.« less

Inflatable robotics for planetary applications

NASA Technical Reports Server (NTRS)

Jones, Jack A.

2001-01-01

Space Inflatable vehicles have been finding popularity in recent years for applications as varied as spacecraft antennas, space-based telescopes, solar sails, and manned habitats [1]. Another branch of space inflatable technology has also considered developing ambient gasfilled, solar balloons for Mars as well as ambient gasfilled inflatable rovers [2]. More recently, some other intriguing space-inflatable vehicles have been proposed for the gas planets and Pluto, as well as for Saturn's moon, Titan, Neptune's moon, Triton, and Jupiter's moon, Io [3].

Dynamical Evolution Induced by Planet Nine

NASA Astrophysics Data System (ADS)

Batygin, Konstantin; Morbidelli, Alessandro

2017-12-01

The observational census of trans-Neptunian objects with semimajor axes greater than ˜ 250 {au} exhibits unexpected orbital structure that is most readily attributed to gravitational perturbations induced by a yet-undetected, massive planet. Although the capacity of this planet to (I) reproduce the observed clustering of distant orbits in physical space, (II) facilitate the dynamical detachment of their perihelia from Neptune, and (III) excite a population of long-period centaurs to extreme inclinations is well-established through numerical experiments, a coherent theoretical description of the dynamical mechanisms responsible for these effects remains elusive. In this work, we characterize the dynamical processes at play from semi-analytic grounds. We begin by considering a purely secular model of orbital evolution induced by Planet Nine and show that it is at odds with the ensuing stability of distant objects. Instead, the long-term survival of the clustered population of long-period Kuiper Belt objects (KBOs) is enabled by a web of mean-motion resonances driven by Planet Nine. Then, by taking a compact-form approach to perturbation theory, we show that it is the secular dynamics embedded within these resonances that regulate the orbital confinement and perihelion detachment of distant KBOs. Finally, we demonstrate that the onset of large-amplitude oscillations of the orbital inclinations is accomplished through the capture of low-inclination objects into a high-order secular resonance, and we identify the specific harmonic that drives the evolution. In light of the developed qualitative understanding of the governing dynamics, we offer an updated interpretation of the current observational data set within the broader theoretical framework of the Planet Nine hypothesis.

The Generation of the Distant Kuiper Belt by Planet Nine from an Initially Broad Perihelion Distribution

NASA Astrophysics Data System (ADS)

Khain, Tali; Batygin, Konstantin; Brown, Michael E.

2018-04-01

The observation that the orbits of long-period Kuiper Belt objects are anomalously clustered in physical space has recently prompted the Planet Nine hypothesis - the proposed existence of a distant and eccentric planetary member of our Solar System. Within the framework of this model, a Neptune-like perturber sculpts the orbital distribution of distant Kuiper Belt objects through a complex interplay of resonant and secular effects, such that the surviving orbits get organized into apsidally aligned and anti-aligned configurations with respect to Planet Nine's orbit. We present results on the role of Kuiper Belt initial conditions on the evolution of the outer Solar System using numerical simulations. Intriguingly, we find that the final perihelion distance distribution depends strongly on the primordial state of the system, and demonstrate that a bimodal structure corresponding to the existence of both aligned and anti-aligned clusters is only reproduced if the initial perihelion distribution is assumed to extend well beyond 36 AU. The bimodality in the final perihelion distance distribution is due to the permanently stable objects, with the lower perihelion peak corresponding to the anti-aligned orbits and the higher perihelion peak corresponding to the aligned orbits. We identify the mechanisms that enable the persistent stability of these objects and locate the regions of phase space in which they reside. The obtained results contextualize the Planet Nine hypothesis within the broader narrative of solar system formation, and offer further insight into the observational search for Planet Nine.

The Effect of Convective Overstability on Planet Disk Interactions

NASA Astrophysics Data System (ADS)

Klahr, Hubert; Gomes, Aiara Lobo

2016-10-01

We run global two dimensional hydrodynamical simulations, using the PLUTO code and the planet-disk model of Uribe et al. 2011, to investigate the effect of the convective overstability (CO) on planet-disk interactions. First, we study the long-term evolution of planet-induced vortices. We found that the CO leads to smoother planetary gap edges, thus weaker planet-induced vortices. The main result was the observation of two generation of vortices, which can pose an explanation for the location of the vortex in the Oph IRS48 system. The lifetime of the primary vortices, as well as the birth time of the secondary vortices are shown to be highly dependent on the thermal relaxation timescale. Second, we study the long-term evolution of the migration of low mass planets and assess whether the CO can prevent the saturation of the horseshoe drag. We found that the disk parameters that favour slow inward or outward migration oppose the amplification of vortices, meaning that the CO does not seem to be a good mechanism to prevent the saturation of the horseshoe drag. On the other hand, we observed a planetary trap, caused by vortices formed in the horseshoe region. This trap may be an alternative mechanism to prevent the fast type I migration rates.

Dusty disc-planet interaction with dust-free simulations

NASA Astrophysics Data System (ADS)

Chen, Jhih-Wei; Lin, Min-Kai

2018-05-01

Protoplanets may be born into dust-rich environments if planetesimals formed through streaming or gravitational instabilities, or if the protoplanetary disc is undergoing mass loss due to disc winds or photoevaporation. Motivated by this possibility, we explore the interaction between low mass planets and dusty protoplanetary discs with focus on disc-planet torques. We implement Lin & Youdin's newly developed, purely hydrodynamic model of dusty gas into the PLUTO code to simulate dusty protoplanetary discs with an embedded planet. We find that for imperfectly coupled dust and high metallicity, e.g. Stokes number 10-3 and dust-to-gas ratio Σd/Σg = 0.5, a `bubble' develops inside the planet's co-orbital region, which introduces unsteadiness in the flow. The resulting disc-planet torques sustain large amplitude oscillations that persists well beyond that in simulations with perfectly coupled dust or low dust-loading, where co-rotation torques are always damped. We show that the desaturation of the co-rotation torques by finite-sized particles is related to potential vorticity generation from the misalignment of dust and gas densities. We briefly discuss possible implications for the orbital evolution of protoplanets in dust-rich discs. We also demonstrate Lin & Youdin's dust-free framework reproduces previous results pertaining to dusty protoplanetary discs, including dust-trapping by pressure bumps, dust settling, and the streaming instability.

Circularizing Planet Nine through dynamical friction with an extended, cold planetesimal belt

NASA Astrophysics Data System (ADS)

Eriksson, Linn E. J.; Mustill, Alexander J.; Johansen, Anders

2018-04-01

Unexpected clustering in the orbital elements of minor bodies beyond the Kuiper belt has led to speculations that our Solar system actually hosts nine planets, the eight established plus a hypothetical `Planet Nine'. Several recent studies have shown that a planet with a mass of about 10 Earth masses on a distant eccentric orbit with perihelion far beyond the Kuiper belt could create and maintain this clustering. The evolutionary path resulting in an orbit such as the one suggested for Planet Nine is nevertheless not easily explained. Here, we investigate whether a planet scattered away from the giant-planet region could be lifted to an orbit similar to the one suggested for Planet Nine through dynamical friction with a cold, distant planetesimal belt. Recent simulations of planetesimal formation via the streaming instability suggest that planetesimals can readily form beyond 100 au. We explore this circularisation by dynamical friction with a set of numerical simulations. We find that a planet that is scattered from the region close to Neptune on to an eccentric orbit has a 20-30 per cent chance of obtaining an orbit similar to that of Planet Nine after 4.6 Gyr. Our simulations also result in strong or partial clustering of the planetesimals; however, whether or not this clustering is observable depends on the location of the inner edge of the planetesimal belt. If the inner edge is located at 200 au, the degree of clustering amongst observable objects is significant.

A Demonstration Setup to Simulate Detection of Planets outside the Solar System

ERIC Educational Resources Information Center

Choopan, W.; Ketpichainarong, W.; Laosinchai, P.; Panijpan, B.

2011-01-01

We constructed a simple demonstration setup to simulate an extrasolar planet and its star revolving around the system's centre of mass. Periodic dimming of light from the star by the transiting planet and the star's orbital revolution simulate the two major ways of deducing the presence of an exoplanet near a distant star. Apart from being a…

Worlds Fantastic, Worlds Familiar

NASA Astrophysics Data System (ADS)

Buratti, Bonnie J.

2017-02-01

Introduction; 1. Mercury: the hottest little place; 2. Venus: an even hotter place; 3. Mars: the abode of life?; 4. Asteroids and comets: sweat the small stuff; 5. Galileo's treasures: worlds of fire and ice; 6. Enceladus: an active iceball in space; 7. Titan: an Earth in deep freeze?; 8. Iapetus and its friends: the weirdest 'planets' in the Solar System; 9. Pluto: the first view of the 'third zone'; 10. Earths above: the search for exoplanets and life in the universe; Epilogue; Glossary; Acknowledgements; Index.

Layered Craters and Icy Plains

NASA Image and Video Library

2015-12-05

This highest-resolution image from NASA's New Horizons spacecraft reveals new details of Pluto's rugged, icy cratered plains. Notice the layering in the interior walls of many craters (the large crater at upper right is a good example) -- layers in geology usually mean an important change in composition or event but at the moment New Horizons team members do not know if they are seeing local, regional or global layering. The darker crater in the lower center is apparently younger than the others, because dark material ejected from within -- its "ejecta blanket" -- have not been erased and can still be made out. The origin of the many dark linear features trending roughly vertically in the bottom half of the image is under debate, but may be tectonic. Most of the craters seen here lie within the 155-mile (250-kilometer)-wide Burney Basin, whose outer rim or ring forms the line of hills or low mountains at bottom. The basin is informally named after Venetia Burney, the English schoolgirl who first proposed the name "Pluto" for the newly discovered planet in 1930. The top of the image is to Pluto's northwest. These images were made with the telescopic Long Range Reconnaissance Imager (LORRI) aboard New Horizons, in a timespan of about a minute centered on 11:36 UT on July 14 -- just about 15 minutes before New Horizons' closest approach to Pluto-- from a range of just 10,000 miles (17,000 kilometers). They were obtained with an unusual observing mode; instead of working in the usual "point and shoot," LORRI snapped pictures every three seconds while the Ralph/Multispectral Visual Imaging Camera (MVIC) aboard New Horizons was scanning the surface. This mode requires unusually short exposures to avoid blurring the images. http://photojournal.jpl.nasa.gov/catalog/PIA20200

Origin and Evolution of Nitrogen on Titan, Enceladus, Triton, and Pluto

NASA Technical Reports Server (NTRS)

Atreya, S. K.; Niemann, H. B.; Mahaffy, P. R.; Owen, T. C.

2007-01-01

Nitrogen, together with carbon, hydrogen, oxygen, phosphorus and sulfur (CHNOPS), plays a central role in life as we know it. Indeed, molecular nitrogen is the most abundant component of the terrestrial atmosphere, and second only to carbon dioxide on Mars and Venus. The Voyager and Cassini-Huygens observations show that copious nitrogen is present on Titan also, comprising some 95% by volume of this moon's 1500 millibar atmosphere. After water vapor, it may be the most abundant (4%) of the gases around tiny Enceladus, as revealed by the recent Cassini observations. A thin nitrogen atmosphere is found even on the coldest of the solar system bodies, Triton and Pluto. The available evidence on nitrogen isotopes and the heavy noble gases suggests that Titan acquired its nitrogen largely in the form of ammonia. Subsequent chemical evolution, beginning with the photolysis of NH3 on primordial Titan, led to the nitrogen atmosphere we see on Titan today. This is also the scenario for the origin of nitrogen on the terrestrial planets. Contrary to Titan, the colder outer solar system objects, Triton and Pluto, neither had the luxury of receiving much arnmonia in the first place, nor of photolyzing whatever little ammonia they did receive in the planetesimals that formed them. On the other hand, it is plausible the planetesimals were capable of trapping and delivering molecular nitrogen directly to Triton and Pluto, unlike Titan. The origin of nitrogen on Enceladus is somewhat enigmatic. A scenario similar to Titan's, but with a role for the interior processes, may be at work. In this paper, we will discuss the source and loss of nitrogen for the above objects, and why Ganymede, the largest moon in the solar system, is nitrogen starved.

A Road Map for the Exploration of Neighboring Planetary Systems (ExNPS)

NASA Technical Reports Server (NTRS)

Elachi, Charles; Angel, Roger; Beichman, Charles A. (Editor); Boss, Alan; Brown, Robert; Dressler, Alan; Dyson, Freeman; Fanson, James; Ftaclas, Chris; Goad, Lawrence;

Radioisotope Electric Propulsion for Fast Outer Planetary Orbiters

NASA Technical Reports Server (NTRS)

Oleson, Steven; Benson, Scott; Gefert, Leon; Patterson, Michael; Schreiber, Jeffrey

2002-01-01

Recent interest in outer planetary targets by the Office of Space Science has spurred the search for technology options to enable relatively quick missions to outer planetary targets. Several options are being explored including solar electric propelled stages combined with aerocapture at the target and nuclear electric propulsion. Another option uses radioisotope powered electric thrusters to reach the outer planets. Past work looked at using this technology to provide faster flybys. A better use for this technology is for outer planet orbiters. Combined with medium class launch vehicles and a new direct trajectory these small, sub-kilowatt ion thrusters and Stirling radioisotope generators were found to allow missions as fast as 5 to 12 years for objects from Saturn to Pluto, respectively. Key to the development is light spacecraft and science payload technologies.

Cosmogonic curve and positions on it of Earth, asteroids, and the outer planets

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2013-09-01

The main point of the comparative wave planetology [1 & others] is the statement: "Orbits make structures". All so different celestial bodies (various sizes, masses, densities, chemichal compositions, physical states, positions in the Universe and so on) have two fundamental properties: movement and rotation. Movements in non-circular (keplerian elliptical, parabolic) orbits with changing accelerations induce in bodies wave warpings (standing waves) which in rotating bodies have 4 orthogonal and diagonal directions. An interference of these directions produces uprising, subsiding and neutral tectonic blocks size of which depends on warping wavelengths. The fundamental wave1 long 2πR (R - a body radius) gives ubiquitous tectonic dichotomy (two hemispheres - segments), the first overtone wave2 long πR produces sectoring. Along with these warpings (wave1 with harmonics) exist tectonic granulations. Granule size depends on orbital frequency: higher frequency - smaller granule, lower frequency - larger granule. Terrestrial planets have the following individual granule sizes (a half of a wavelength): Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1 (Fig. 1, bottom). These granule producing warpings tend to bring planetary spheres to polyhedrons which, for simplicity, are represented by the following figures inscribed in the planetary circles: Mercury- 16-gon, Venus- hexagon, Earth- square, Mars- rectangle, asteroids - line (Fig. 2). Obviously, nearer a figure to circle more it is stable, and this is expressed by the ratio of a figure area to the circle area. Mercury has 0.973, Venus 0.830, Earth 0.637, Mars 0.420, asteroids 0. The line for asteroids means the zero ratio, thus zero stability and no planet in the asteroid zone. Earth is unique by its near to the "golden section" value. In Fig. 1 both axes are logarithmic: the abscissa - solar distances of the planets, the ordinate - relative granule sizes (ratio of an individual wave to the fundamental wave). Before the asteroid belt individual waves are shorter than the fundamental wave, after the belt - an opposite relation occurs. Thus the asteroid belt crosses the ordinate 1 what means that there is the very strong 1 : 1 resonance between the fundamental and the individual waves prohibiting a planet (Phaethon) formation. Available material is scattered leading to a known matter deficit. The constructed cosmogonic curve is a curve with a bending point. Earth occurs at this peculiar place what determines Earth uniqueness. The heliocentric distance is then mathematically the abscissa of the bending point (Fig. 1). In the outer planets zone regularly increasing warping wavelengths begin to exceed the fundamental wavelength. The giant planets resist to destructive high amplitude oscillations thanks to their large gravitational compression and elasticity. Nevertheless they also lose a part of their matter ejecting it into near planet space where it gathers up as systems of satellites and rings. Such ejections could explain appearance of non-regular satellites, arcs in rings and other "anomalous" phenomena. Pluto bears vivid marks of destructive oscillations. It has large bulge or is torn in two parts (second core or large satellite) and "chaotically" moves in orbit. The chaos is most probably caused by a distortion of its orbit by its own high amplitude oscillations. Approaching the 100 : 1 resonance (Fig. 1) tells on significant matter deficit in the Pluto's orbit and its increased density. Decimal resonances (1:1,10:1, 100:1) are marked by a matter deficit. Planetary masses relative to the Earth's mass are as follows: Mercury 0.06; Venus 0.82; Earth 1.00; Mars 0.11; Asteroids 0.001(mass deficit); Jupiter 318; Saturn 95.1; (mass deficit) Uranus 14.5; Neptune 17.3; Pluto 0.002 (mass deficit). References: [1]Kochemasov G.G. (1992)16th Russian-American microsymposium on planetology, Abstracts, Moscow, Vernadsky Inst. (GEOKHI), 36-37.

Tidal-Rotational Dynamics of Solar System Worlds, from the Moon to Pluto

NASA Astrophysics Data System (ADS)

Keane, James Tuttle

The spins of planetary bodies are not stagnant; they evolve in response to both external and internal forces. One way a planet's spin can change is through true polar wander. True polar wander is the reorientation of a planetary body with respect to its angular momentum vector, and occurs when mass is redistributed within the body, changing its principal axes of inertia. True polar wander can literally reshape a world, and has important implications for a variety of processes--from the long-term stability of polar volatiles in the permanently shadowed regions of airless worlds like the Moon and Mercury, to the global tectonic patterns of icy worlds like Pluto. In this dissertation, we investigate three specific instances of planetary true polar wander, and their associated consequences. In Chapter 2 we investigate the classic problem of the Moon's dynamical figure. By considering the effects of a fossil figure supported by an elastic lithosphere, and the contribution of impact basins to the figure, we find that the lunar figure is consistent with the Moon's lithosphere freezing in when the Moon was much closer to the Earth, on a low eccentricity synchronous orbit. The South Pole-Aitken impact basin is the single largest perturbation to the Moon's figure and resulted in tens of degrees of true polar wander after its formation. In Chapter 3 we continue our analyses of the lunar figure in light of the discovery of a lunar "volatile" paleopole, preserved in the distribution of hydrogen near the Moon's poles. We find that the formation and evolution of the Procellarum KREEP Terrain significantly altered the Moon's orientation, implying that some fraction of the Moon's polar volatiles are ancient--predating the geologic activity within the Procellarum region. In Chapter 4 we investigate how the formation of the giant, basin-filling glacier, Sputnik Planitia reoriented Pluto. This reorientation is recorded in both the present- day location of Sputnik Planitia (near the Pluto-Charon tidal axis), and the tectonic record of Pluto. This reorientation likely reflects a coupling between Pluto's volatile cycles and rotational dynamics, and may be active on other worlds with comparably large, mobile volatile reservoirs. Finally, in Chapter 5 we consider the broader context of these studies, and touch on future investigations of true polar wander on Mercury, Venus, Mars, Vesta, Ceres, and other worlds in our solar system.

Robotic planetary science missions enabled with small NTR engine/stage technologies

NASA Astrophysics Data System (ADS)

Borowski, Stanley K.

1995-10-01

The high specific impulse (Isp) and engine thrust-to-weight ratio of liquid hydrogen (LH2)-cooled nuclear thermal rocket (NTR) engines makes them ideal for upper stage applications to difficult robotic planetary science missions. A small 15 thousand pound force (klbf) NTR engine using a uranium-zirconium-niobium 'ternary carbide' fuel (Isp approximately 960 seconds at approximately 3025K) developed in the Commonwealth of Independent States (CIS) is examined and its use on an expendable injection stage is shown to provide major increases in payload delivered to the outer planets (Saturn, Uranus, Neptune and Pluto). Using a single 'Titan IV-class' launch vehicle, with a lift capability to low Earth orbit (LEO) of approximately 20 metric tons (t), an expendable NTR upper stage can inject two Pluto 'Fast Flyby' spacecraft (PFF/SC) plus support equipment-combined mass of approximately 508 kg--on high energy, '6.5-9.2 year' direct trajectory missions to Pluto. A conventional chemical propulsion mission would use a liquid oxygen (LOX)/LH2 'Centaur' upper stage and two solid rocket 'kick motors' to inject a single PFF/SC on the same Titan IV launch vehicle. For follow on Pluto missions, the NTR injection stage would utilize a Jupiter 'gravity assist' (JGA) maneuver to launch a LOX/liquid methane (CH4) capture stage (Isp approximately 375 seconds) and a Pluto 'orbiter' spacecraft weighing between approximately 167-312 kg. With chemical propulsion, a Pluto orbiter mission is not a viable option because c inadequate delivered mass. Using a 'standardized' NTR injection stage and the same single Titan IV launch scenario, 'direct flight' (no gravity assist) orbiter missions to Saturn, Uranus and Neptune are also enabled with transit times of 2.3, 6.6, and 12.6 years, respectively. Injected mass includes a storable, nitrogen tetroxide/monomethyl hydrazine (N2O4/MMH) capture stage (Isp approximately 330 seconds) and orbiter payloads 340 to 820% larger than that achievable using a LOX/LH2-fueled injection stage. The paper discusses NTR technology and mission characteristics, shows NTR stage and payload accommodations within the 26.2 m long Titan IV payload fairing, and discusses NTR stage performance as a function of assumed cryogenic tank technology.

Robotic Planetary Science Missions Enabled with Small NTR Engine/Stage Technologies

NASA Technical Reports Server (NTRS)

Borowski, Stanley K.

1995-01-01

The high specific impulse (Isp) and engine thrust-to-weight ratio of liquid hydrogen (LH2)-cooled nuclear thermal rocket (NTR) engines makes them ideal for upper stage applications to difficult robotic planetary science missions. A small 15 thousand pound force (klbf) NTR engine using a uranium-zirconium-niobium 'ternary carbide' fuel (Isp approximately 960 seconds at approximately 3025K) developed in the Commonwealth of Independent States (CIS) is examined and its use on an expendable injection stage is shown to provide major increases in payload delivered to the outer planets (Saturn, Uranus, Neptune and Pluto). Using a single 'Titan IV-class' launch vehicle, with a lift capability to low Earth orbit (LEO) of approximately 20 metric tons (t), an expendable NTR upper stage can inject two Pluto 'Fast Flyby' spacecraft (PFF/SC) plus support equipment-combined mass of approximately 508 kg--on high energy, '6.5-9.2 year' direct trajectory missions to Pluto. A conventional chemical propulsion mission would use a liquid oxygen (LOX)/LH2 'Centaur' upper stage and two solid rocket 'kick motors' to inject a single PFF/SC on the same Titan IV launch vehicle. For follow on Pluto missions, the NTR injection stage would utilize a Jupiter 'gravity assist' (JGA) maneuver to launch a LOX/liquid methane (CH4) capture stage (Isp approximately 375 seconds) and a Pluto 'orbiter' spacecraft weighing between approximately 167-312 kg. With chemical propulsion, a Pluto orbiter mission is not a viable option because c inadequate delivered mass. Using a 'standardized' NTR injection stage and the same single Titan IV launch scenario, 'direct flight' (no gravity assist) orbiter missions to Saturn, Uranus and Neptune are also enabled with transit times of 2.3, 6.6, and 12.6 years, respectively. Injected mass includes a storable, nitrogen tetroxide/monomethyl hydrazine (N2O4/MMH) capture stage (Isp approximately 330 seconds) and orbiter payloads 340 to 820% larger than that achievable using a LOX/LH2-fueled injection stage. The paper discusses NTR technology and mission characteristics, shows NTR stage and payload accommodations within the 26.2 m long Titan IV payload fairing, and discusses NTR stage performance as a function of assumed cryogenic tank technology.

The search for life on Earth and other planets.

PubMed

Gross, Michael

2012-04-10

As the NASA rover Curiosity approaches Mars on its quest to look for signs of past or present life there and sophisticated instruments like the space telescopes Kepler and CoRoT keep discovering additional, more Earth-like planets orbiting distant stars, science faces the question of how to spot life on other planets. Even here on Earth biotopes remain to be discovered and explored.

Peering Into Distant Lands: The Geology of Pluto and Charon as Revealed by New Horizons

NASA Astrophysics Data System (ADS)

Umurhan, Orkan; Spencer, John; McKinnon, William; Weaver, Harold; Olkin, Cathy; Ennico, Kimberly; Young, Leslie; Moore, Jeffrey M.; Stern, S. Alan

2016-07-01

The New Horizons spacecraft's close-encounter with Pluto and Charon has revealed these two planetary bodies to have strikingly different surface appearances despite their similar densities and (presumed) compositions [1,2]. Pluto's surface landforms are varied but most appear to be a consequence of surface-atmosphere interactions and insolation mobilization of volatile ices. Pluto exhibits an abundance of valley systems that appear to be shaped by glacial dynamics involving N_{2} ice. N_{2} and (possibly) CO ice appears to be involved in solid-state convection in the 3-4 km deep, 900 km wide equatorial region called Sputnik Planum [3] with convection pattern size scales ranging from 15-40 km. Calculations involving known properties of volatiles under Pluto's current conditions show that Pluto's radiogenic heat loss is enough to power advection and convection of volatile ices. The Piri Planitia/Rupes complex, located in the uplands west of Sputnik Planum, appears to be a landform undergoing scarp retreat driven by the sublimation of CH_{4} gas. The prominent mountain ranges found on the western margin of Sputnik Planum, including Norgay and Hillary Montes, as well as the odd-looking mound features (possibly cryovolcanic) found to the south, like the 3-4 km high Wright Mons, are likely composed of H_{2}O ice and appear to be geologically young - as suggested by their light cratering and superposition relationships. What drives the formation and development of these Plutonian structures so late in Solar System history remains puzzling and is under investigation. While also harboring geologically varied features, Charon's terrain is heavily cratered and appears to be 4 Ga old and lacks obvious evidence of dynamic remolding by volatile transport. Oz Terra, in the northern portion of the encounter hemisphere, exhibits extremely rugged terrain with craters up to 240 km in diameter and a network of polygonal troughs as deep as 10 km. Oz Terra is separated from the southern smooth terrain called Vulcan Planum by a series of graben and tilted blocks indicative of a past and rather vigorous endogenic phase expressed through tectonism. The presence of 1 - 2 km high convex marginal scarps, some of which form moats around isolated mountains, suggests that a viscous fluid, possibly an ammonia/water mixture, was responsible for surfacing the plains of Vulcan Planum. Many young craters, including Nasreddin crater, show conspicuous light and dark rays - suggesting subsurface inhomogeneities. Speculations as to the geologic histories of these two bodies will be discussed. References [1] Stern, S. A. et al. (2015) Science, 350, 292. [2] Moore et al. (2016) Science, in press. [3] All place names on Pluto and Charon are informal.

Recovering Neptune 170 Years After its Initial Discovery

NASA Astrophysics Data System (ADS)

Myles, Justin

2017-01-01

Recent work by Trujillo and Shephard (2014) and Batygin and Brown (2016) has shown an as-yet unexplained clustering of the periapse vectors of the most distant Kuiper Belt objects. This unusual clustering has motivated the search for an unseen perturbing planet that is responsible for maintaining the alignment. As a proof of concept of a technique for locating unseen solar system planets, we use dynamical N-body integrations to simulate the orbital dynamics of distant Kuiper Belt objects, with the aim of determining the orbital parameters of Neptune (which, for the sake of exercise, we assume is, as-yet, undiscovered). In this poster, we determine the accuracy with which the perturbing planet’s orbital elements and sky location can be determined, and we show how the lessons learned can improve the search strategy for potentially undiscovered trans-Neptunian planets.

The Generation of the Distant Kuiper Belt by Planet Nine from an Initially Broad Perihelion Distribution

NASA Astrophysics Data System (ADS)

Khain, Tali; Batygin, Konstantin; Brown, Michael E.

2018-06-01

The observation that the orbits of long-period Kuiper Belt objects (KBOs) are anomalously clustered in physical space has recently prompted the Planet Nine hypothesis—the proposed existence of a distant and eccentric planetary member of our solar system. Within the framework of this model, a Neptune-like perturber sculpts the orbital distribution of distant KBOs through a complex interplay of resonant and secular effects, such that in addition to perihelion-circulating objects, the surviving orbits get organized into apsidally aligned and anti-aligned configurations with respect to Planet Nine’s orbit. In this work, we investigate the role of Kuiper Belt initial conditions on the evolution of the outer solar system using numerical simulations. Intriguingly, we find that the final perihelion distance distribution depends strongly on the primordial state of the system, and we demonstrate that a bimodal structure corresponding to the existence of both aligned and anti-aligned clusters is only reproduced if the initial perihelion distribution is assumed to extend well beyond ∼36 au. The bimodality in the final perihelion distance distribution is due to the existence of permanently stable objects, with the lower perihelion peak corresponding to the anti-aligned orbits and the higher perihelion peak corresponding to the aligned orbits. We identify the mechanisms that enable the persistent stability of these objects and locate the regions of phase space in which they reside. The obtained results contextualize the Planet Nine hypothesis within the broader narrative of solar system formation and offer further insight into the observational search for Planet Nine.

The Surfaces of Pluto and Charon

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.; Roush, Ted L.; Moore, Jeffrey M.; Sykes, Mark V.; Owen, Tobias C.; Bartholomew, Mary Jane; Brown, Robert H.; Tryka, Kimberly A.

1996-01-01

Much of the surface of Pluto consists of high-albedo regions covered to an unknown depth by Beta-N2, contaminated with CH4, CO, and other molecules. A portion of the exposed surface appears to consist of solid H2O. The remainder is covered by lower albedo material of unknown composition. The N2 ice may occur as polar caps of large extent, leaving ices and other solids of lower volatility in the equatorial regions. The low-albedo material found primarily in the equatorial regions may consist in part of solid hydrocarbons and nitriles produced from N2 and CH4 in the atmosphere or in the surface ices. Alternatively, it may arise from deposition from impacting bodies and/or the chemistry of the impact process itself. Charon's surface is probably more compositionally uniform than that of Pluto, and is covered by H2O ice with possible contaminants or exposures of other materials that are as yet unidentified. The molecular ices discovered on Pluto and Charon have been identified from near-infrared spectra obtained with Earth-based telescopes. The quantitative interpretation of those data has been achieved through the computation of synthetic spectra using the Hapke scattering theory and the optical constants of various ices observed in the laboratory. Despite limitations imposed by the availability of laboratory data on ices in various mixtures, certain specific results have been obtained. It appears that CH4 and CO are trace constituents, and that some fraction of the CH4 (and probably the CO) on Pluto is dissolved in the matrix of solid N2. Pure CH4 probably also occurs on Pluto's surface, allowing direct access to the atmosphere. Study of the nitrogen absorption band at 2.148 micrometers shows that the temperature of the N2 in the present epoch is 40 +/-2 K. The global temperature regime of Pluto can be modeled from observations of the thermal flux at far-infrared and millimeter wavelengths. The low-albedo equatorial regions must be significantly warmer than the polar regions covered by N2 (at T = 40 K) to account for the total thermal flux measured. At the present season, the diurnal skin depth of the insolation-driven thermal wave is small, and the observed mm-wave fluxes may arise from a greater depth. Alternatively, the mm-wave flux may arise from the cool, sublimation source region. The surface microstructure in the regions covered by N2 ice is likely governed by the sintering properties of this highly volatile material. The observed nitrogen infrared band strength requires that expanses of the surface be covered with cm-sized crystals of N2. Grains of H2O ice on Charon, in contrast, are probably of order 50 micrometers in size, and do not metamorphose into larger grains at a significant rate. Because of the similarities in size, density, atmosphere and surface composition between Pluto and Neptune's satellite Triton, the surface structures observed by Voyager on Triton serve as a plausible paradigm for what might be expected on Pluto. Such crater forms, tectonic structures, aeolian features, cryovolcanic structures, and sublimation-degraded topography as are eventually observed on Pluto and Charon by spacecraft will give information on their interior compositions and structures, as well as on the temperature and wind regimes over the planet's extreme seasonal cycle.

Wright Stuff

NASA Image and Video Library

2016-01-14

Scientists with NASA New Horizons mission have assembled the highest-resolution color view of one of two potential cryovolcanoes spotted on the surface of the distant planet by the passing New Horizons spacecraft in July 2015. At about 90 miles (150 kilometers) across and 2.5 miles (4 kilometers) high, the feature -- informally named Wright Mons -- is enormous. If it is in fact a volcano, as suspected, it would be the largest such feature discovered in the outer solar system. Mission scientists are intrigued by the sparse distribution of red material in the image and wonder why it is not more widespread. Also perplexing is that there is only one identified impact crater on Wright Mons itself, telling scientists that the surface (as well as some of the crust underneath) was created relatively recently. This is turn may indicate that Wright Mons was volcanically active late in Pluto's history. This composite image includes pictures taken by the New Horizons spacecraft's Long Range Reconnaissance Imager (LORRI) on July 14, 2015, from a range of about 30,000 miles (48,000 kilometers), showing features as small as 1,500 feet (450 meters) across. Sprinkled across the LORRI mosaic is enhanced color data from the Ralph/Multispectral Visible Imaging Camera (MVIC) gathered about 20 minutes after the LORRI snapshots were taken, from a range of 21,000 miles (34,000 kilometers) and at a resolution of about 2,100 feet (650 meters) per pixel. The entire scene is 140 miles (230 kilometers) across. http://photojournal.jpl.nasa.gov/catalog/PIA20361

Observational Constraints on the Orbit and Location of Planet Nine in the Outer Solar System

NASA Astrophysics Data System (ADS)

Brown, Michael E.; Batygin, Konstantin

2016-06-01

We use an extensive suite of numerical simulations to constrain the mass and orbit of Planet Nine, the recently proposed perturber in a distant eccentric orbit in the outer solar system. We compare our simulations to the observed population of aligned eccentric high semimajor axis Kuiper belt objects (KBOs) and determine which simulation parameters are statistically compatible with the observations. We find that only a narrow range of orbital elements can reproduce the observations. In particular, the combination of semimajor axis, eccentricity, and mass of Planet Nine strongly dictates the semimajor axis range of the orbital confinement of the distant eccentric KBOs. Allowed orbits, which confine KBOs with semimajor axis beyond 380 au, have perihelia roughly between 150 and 350 au, semimajor axes between 380 and 980 au, and masses between 5 and 20 Earth masses. Orbitally confined objects also generally have orbital planes similar to that of the planet, suggesting that the planet is inclined approximately 30°to the ecliptic. We compare the allowed orbital positions and estimated brightness of Planet Nine to previous and ongoing surveys which would be sensitive to the planet’s detection and use these surveys to rule out approximately two-thirds of the planet’s orbit. Planet Nine is likely near aphelion with an approximate brightness of 22< V< 25. At opposition, its motion, mainly due to parallax, can easily be detected within 24 hours.

Deep Space Detectives: Searching for Planets Suitable for Life

ERIC Educational Resources Information Center

Pallant, Amy; Damelin, Daniel; Pryputniewicz, Sarah

2013-01-01

This article describes the High-Adventure Science curriculum unit "Is There Life in Space?" This free online investigation, developed by The Concord Consortium, helps students see how scientists use modern tools to locate planets around distant stars and explore the probability of finding extraterrestrial life. This innovative curriculum…

Feasibility of infrared Earth tracking for deep-space optical communications.

PubMed

Chen, Yijiang; Hemmati, Hamid; Ortiz, Gerry G

2012-01-01

Infrared (IR) Earth thermal tracking is a viable option for optical communications to distant planet and outer-planetary missions. However, blurring due to finite receiver aperture size distorts IR Earth images in the presence of Earth's nonuniform thermal emission and limits its applicability. We demonstrate a deconvolution algorithm that can overcome this limitation and reduce the error from blurring to a negligible level. The algorithm is applied successfully to Earth thermal images taken by the Mars Odyssey spacecraft. With the solution to this critical issue, IR Earth tracking is established as a viable means for distant planet and outer-planetary optical communications. © 2012 Optical Society of America

How do external companions affect spin-orbit misalignment of hot Jupiters?

NASA Astrophysics Data System (ADS)

Lai, Dong; Anderson, Kassandra R.; Pu, Bonan

2018-04-01

Consider a planet with its orbital angular momentum axis aligned with the spin axis of its host star. To what extent does an inclined distant companion (giant planet or binary star) affect this alignment? We provide an analytic, quantitative answer and apply it to hot Jupiter systems, for which misalignments between the orbital axis and the stellar spin axis have been detected. We also show how similar consideration can be applied to multiplanet systems with distant companions (such as Kepler-56). The result of this paper provides a simple method to assess the dynamical role played by external companions on spin-orbit misalignments in exoplanetary systems.

Polar Wander on Triton and Pluto Due to Volatile Migration

NASA Technical Reports Server (NTRS)

Rubincam, David Parry

2002-01-01

Polar wander may occur on Triton and Pluto because of volatile migration. Triton, with its low obliquity, can theoretically sublimate volatiles (mostly nitrogen) at the rate of approximately 10(exp 14) kilograms per year from the equatorial regions and deposit them at the poles. Assuming Triton to be rigid on the sublimation timescale, after approximately 10(exp 5) years the polar caps would become large enough to cancel the rotational flattening, with a total mass equivalent to a global layer approximately 120-250 m in depth. At this point the pole wanders about the tidal bulge axis, which is the line joining Triton and Neptune. Rotation about the bulge axis might be expected to disturb the leading side/trailing side cratering statistics. Because no such disturbance is observed, it may be that Triton's mantle viscosity is too high but its surface volatile inventory is too low to permit wander. On the other hand, its mantle viscosity might be low, so that any uncompensated cap load might be expected to wander toward the tidal bulge axis. In this case, the axis of wander passes through the equator from the leading side to the trailing side; rotation about this wander axis would not disturb the cratering statistics. Low-viscosity polar wander may explain the bright southern hemisphere: this is the pole which is wandering toward the equator. In any case the permanent polar caps may be geologically very young. Polar wander may possibly take place on Pluto, due to its obliquity oscillations and perihelion-pole geometry. However, Pluto is probably not experiencing any wander at present. The Sun has been shining strongly on the poles over the last half of the obliquity cycle, so that volatiles should migrate to the equator, stabilizing the planet against wander. Spacecraft missions to Triton and Pluto which measure the dynamical flattening could give information about the accumulation of volatiles at the poles. Such information is best obtained by measuring gravity and topography from orbiters, as was done for Mars with the highly successful Mars Global Surveyor.

CIRCUMBINARY CHAOS: USING PLUTO'S NEWEST MOON TO CONSTRAIN THE MASSES OF NIX AND HYDRA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Youdin, Andrew N.; Kratter, Kaitlin M.; Kenyon, Scott J.

The Pluto system provides a unique local laboratory for the study of binaries with multiple low-mass companions. In this paper, we study the orbital stability of P4, the most recently discovered moon in the Pluto system. This newfound companion orbits near the plane of the Pluto-Charon (PC) binary, roughly halfway between the two minor moons Nix and Hydra. We use a suite of few body integrations to constrain the masses of Nix and Hydra, and the orbital parameters of P4. For the system to remain stable over the age of the solar system, the masses of Nix and Hydra likelymore » do not exceed 5 Multiplication-Sign 10{sup 16} kg and 9 Multiplication-Sign 10{sup 16} kg, respectively. These upper limits assume a fixed mass ratio between Nix and Hydra at the value implied by their median optical brightness. Our study finds that stability is more sensitive to their total mass and that a downward revision of Charon's eccentricity (from our adopted value of 0.0035) is unlikely to significantly affect our conclusions. Our upper limits are an order of magnitude below existing astrometric limits on the masses of Nix and Hydra. For a density at least that of ice, the albedos of Nix and Hydra would exceed 0.3. This constraint implies they are icy, as predicted by giant impact models. Even with these low masses, P4 only remains stable if its eccentricity e {approx}< 0.02. The 5:1 commensurability with Charon is particularly unstable, combining stability constraints with the observed mean motion places the preferred orbit for P4 just exterior to the 5:1 resonance. These predictions will be tested when the New Horizons satellite visits Pluto. Based on the results for the PC system, we expect that circumbinary, multi-planet systems will be more widely spaced than their singleton counterparts. Further, circumbinary exoplanets close to the three-body stability boundary, such as those found by Kepler, are less likely to have other companions nearby.« less

Earth, Meet Pluto: The New Horizons Education and Communications Partnership

NASA Astrophysics Data System (ADS)

Buckley, M.

2015-12-01

The unique partnership between the NASA New Horizons education/communications and public affairs programs tapped into the excitement of visiting an unexplored planet in a new region of the solar system - resulting in unprecedented public participation in and coverage of a planetary mission. With a range of hands-on learning experiences, Web materials and online , the program provided opportunities for students, educators, museums, science centers, the media, Web surfers and other members of the public to ride along on the first mission to Pluto and the Kuiper Belt. The programs leveraged resources, materials and expertise to address a wide range of traditional and nontraditional audiences while providing consistent messages and information on this historic NASA endeavor. The E/C program included a variety of formal lesson plans and learning materials — based on New Horizons science and engineering goals, and aligned with National Research Council's National Science Education Standards — that continue to help students in grades K-12 learn more about science, technology, engineering and mathematics. College students designed and built an actual flight instrument on New Horizons and held internships with the spacecraft integration and test team. New Horizons E/C programs went well beyond the classroom, from a chance for people to send their names to Pluto on board the New Horizons spacecraft before launch, to opportunities for the public to access milestone events and the first-ever close-up views of Pluto in places such as museums, science centers and libraries, TV and the Web — as well as thousands who attended interactive "Plutopalooza" road shows across the country. Teamed with E/C was the public affairs strategy to communicate New Horizons news and messages to media, mission stakeholders, the scientific community and the public. These messages include various aspects of New Horizons, including the progress of the mission and key milestones and achievements; the unique, long-distance operation of the spacecraft and its instruments; and the release of scientific data and results from New Horizons' historic Pluto encounter. Through traditional and social media channels the mission reached billions of people worldwide - and likely inspired millions among the next generation of STEM professionals.

A Herschel-Detected Correlation between Planets and Debris Disks

NASA Astrophysics Data System (ADS)

Bryden, Geoffrey; Krist, J. E.; Stapelfeldt, K. R.; Kennedy, G.; Wyatt, M.; Beichman, C. A.; Eiroa, C.; Marshall, J.; Maldonado, J.; Montesinos, B.; Moro-Martin, A.; Matthews, B. C.; Fischer, D.; Ardila, D. R.; Kospal, A.; Rieke, G.; Su, K. Y.

2013-01-01

The Fomalhaut, beta Pic, and HR 8799 systems each have directly imaged planets and prominent debris disks, suggesting a direct link between the two phenomena. Unbiased surveys with Spitzer, however, failed to find a statistically significant correlation. We present results from SKARPS (the Search for Kuiper belts Around Radial-velocity Planet Stars) a Herschel far-IR survey for debris disks around solar-type stars known to have orbiting planets. The identified disks are generally cold and distant 50 K/100 AU), i.e. well separated from the radial-velocity-discovered planets. Nevertheless, we find a strong correlation between the inner planets and outer disks, with disks around planet-bearing stars tending to be much brighter than those not known to have planets.

Radioisotope thermophotovoltaic system design and its application to an illustrative space mission

NASA Astrophysics Data System (ADS)

Schock, A.; Kumar, V.

1995-01-01

The paper describes the results of a DOE-sponsored design study of a radioisotope thermophotovoltaic generator (RTPV), to complement similar studies of Radioisotope Thermoelectric Generators (RTGs) and Stirling Generators (RSGs) previously published by the author. Instead of conducting a generic study, it was decided to focus the design effort by directing it at a specific illustrative space mission, Pluto Fast Flyby (PFF). That mission, under study by JPL, envisages a direct eight-year flight to Pluto (the only unexplored planet in the solar system), followed by comprehensive mapping, surface composition, and atmospheric structure measurements during a brief flyby of the planet and its moon Charon, and transmission of the recorded science data to Earth during a post-encounter cruise lasting up to one year. Because of Pluto's long distance from the sun (30-50 A.U.) and the mission's large energy demand, JPL has baselined the use of a radioisotope power system for the PFF spacecraft. TRGs have been tentatively selected, because they have been successfully flown on many space missions, and have demonstrated exceptional reliability and durability. The only reason for exploring the applicability of the far less mature RTPV systems is their potential for much higher conversion efficiencies, which would greatly reduce the mass and cost of the required radioisotope heat source. Those attributes are particularly important for the PFF mission, which—like all NASA missions under current consideration—is severely mass- and cost-limited. The paper describes the design of the radioisotope heat source, the thermophotovoltaic converter, and the heat rejection system; and depicts its integration with the PFF spacecraft. A companion paper presented at this conference presents the results of the thermal, electrical, and structural analysis and the design optimization of the integrated RTPV system. It also discusses the programmatic implications of the analytical results, which suggest that the RTPV generator, when developed by DOE and/or NASA, would be quite valuable not only for the PFF mission but also for other future missions requiring small, long-lived, low-mass generators.

Guidance and navigation requirements for unmanned flyby and swingby missions to the outer planets. Volume 4: High thrust mission, part 2, phase C

NASA Technical Reports Server (NTRS)

1971-01-01

The guidance and navigation requirements for a set of impulsive thrust missions involving one or more outer planets or comets. Specific missions considered include two Jupiter entry missions of 800 and 1200 day duration, two multiple swingby missions with the sequences Jupiter-Uranus-Neptune and Jupiter-Saturn-Pluto, and two comets rendezvous missions involving the short period comets P/Tempel 2 and P/Tuttle-Giacobini-Kresak. Results show the relative utility of onboard and Earth-based DSN navigation. The effects of parametric variations in navigation accuracy, measurement rate, and miscellaneous constraints are determined. The utility of a TV type onboard navigation sensor - sighting on planetary satellites and comets - is examined. Velocity corrections required for the nominal and parametrically varied cases are tabulated.

Creation of fully vectorized FORTRAN code for integrating the movement of dust grains in interplanetary environments

NASA Technical Reports Server (NTRS)

Colquitt, Walter

1989-01-01

The main objective is to improve the performance of a specific FORTRAN computer code from the Planetary Sciences Division of NASA/Johnson Space Center when used on a modern vectorizing supercomputer. The code is used to calculate orbits of dust grains that separate from comets and asteroids. This code accounts for influences of the sun and 8 planets (neglecting Pluto), solar wind, and solar light pressure including Poynting-Robertson drag. Calculations allow one to study the motion of these particles as they are influenced by the Earth or one of the other planets. Some of these particles become trapped just beyond the Earth for long periods of time. These integer period resonances vary from 3 orbits of the Earth and 2 orbits of the particles to as high as 14 to 13.

Communicating with Light: A New Dawn in the Information Age

NASA Technical Reports Server (NTRS)

Raible, Daniel

2016-01-01

You and I are living in a very special time; the age of Solar System exploration. Our Solar System is a complex masterpiece of which we knew so little from our ground-based observations. But within the span of a single lifetime, NASA has sent spacecraft to every planet and several moons, our first eyes to set upon undiscovered lands. Before we endeavored on this journey everything we knew of Pluto could have fit on a single file card, and now we downlink new data every day.

Orbital Evolution of Jupiter-Family Comets

NASA Technical Reports Server (NTRS)

Ipatov, S. I.; Mather, J. S.; Oegerle, William R. (Technical Monitor)

2002-01-01

We investigated the evolution for periods of at least 5-10 Myr of 2500 Jupiter-crossing objects (JCOs) under the gravitational influence of all planets, except for Mercury and Pluto (without dissipative factors). In the first series we considered N=2000 orbits near the orbits of 30 real Jupiter-family comets with period less than 10 yr, and in the second series we took 500 orbits close to the orbit of Comet 10P Tempel 2. We calculated the probabilities of collisions of objects with the terrestrial planets, using orbital elements obtained with a step equal to 500 yr and then summarized the results for all time intervals and all bodies, obtaining the total probability P(sub sigma) of collisions with a planet and the total time interval T(sub sigma) during which perihelion distance of bodies was less than a semimajor axis of the planet. The values of P = 10(exp 6)P(sub sigma)/N and T = T(sub sigma)/1000 yr are presented in Table together with the ratio r of the total time interval when orbits were of Apollo type (at e less than 0.999) to that of Amor type.

Migration of Trans-Neptunian Objects to a Near-Earth Space

NASA Technical Reports Server (NTRS)

Ipatov, S. I.; Mather, J. C.; Oegerle, William (Technical Monitor)

2002-01-01

Our estimates of the migration of trans-Neptunian objects (TNOs) to a near-Earth space are based on the results of investigations of orbital evolution of TNOs and Jupiter-crossing objects (JCOs). The orbital evolution of TNOs was considered in many papers. Recently we investigated the evolution for intervals of at least 5-10 Myr of 2500 JCOs under the gravitational influence of all planets, except for Mercury and Pluto (without dissipative factors). In the first series we considered N=2000 orbits near the orbits of 30 real Jupiter-family comets with period P(sub alpha)less than 10 yr, and in the second series we took N=500 orbits close to the orbit of Comet 10P Tempel 2 (alpha=3.1 AU, e=0.53, i=12 deg). We calculated the probabilities of collisions of objects with the terrestrial planets, using orbital elements obtained with a step equal to 500 yr, and then summarized the results for all time intervals and all bodies, obtaining the total probability P(sub sigma) of collisions with a planet and the total time interval T(sub sigma) during which perihelion distance q of bodies was less than a semimajor axis of the planet.

Dust ablation in Pluto's atmosphere

NASA Astrophysics Data System (ADS)

Horanyi, Mihaly; Poppe, Andrew; Sternovsky, Zoltan

2016-04-01

Based on measurements by dust detectors onboard the Pioneer 10/11 and New Horizons spacecraft the total production rate of dust particles born in the Edgeworth Kuiper Belt (EKB) has been be estimated to be on the order of 5 ṡ 103 kg/s in the approximate size range of 1 - 10 μm. Dust particles are produced by collisions between EKB objects and their bombardment by both interplanetary and interstellar dust particles. Dust particles of EKB origin, in general, migrate towards the Sun due to Poynting-Robertson drag but their distributions are further sculpted by mean-motion resonances as they first approach the orbit of Neptune and later the other planets, as well as mutual collisions. Subsequently, Jupiter will eject the vast majority of them before they reach the inner solar system. The expected mass influx into Pluto atmosphere is on the order of 200 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that volatile rich particles can fully sublimate due to drag heating and deposit their mass in narrow layers. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles by comparing the altitude of the deposition layers to the observed haze layers.

Pluto and it's moon Charon Shine in False Color

NASA Image and Video Library

2017-12-08

**This image was taken at 3:38 a.m. EDT on July 13, one day before New Horizons’ closest approach to Pluto.** New Horizons has obtained impressive new images of Pluto and its large moon Charon that highlight their compositional diversity. These are not actual color images of Pluto and Charon—they are shown here in exaggerated colors that make it easy to note the differences in surface material and features on each planetary body. The images were obtained using three of the color filters of the “Ralph” instrument on July 13 at 3:38 am EDT. New Horizons has seven science instruments on board the spacecraft—including “Ralph” and “Alice”, whose names are a throwback to the “Honeymooners,” a popular 1950s sitcom. “These images show that Pluto and Charon are truly complex worlds. There's a whole lot going on here,” said New Horizons co-investigator Will Grundy, Lowell Observatory, Flagstaff, Arizona. “Our surface composition team is working as fast as we can to identify the substances in different regions on Pluto and unravel the processes that put them where they are.” The color data helps scientists understand the molecular make-up of ices on the surfaces of Pluto and Charon, as well as the age of geologic features such as craters. They can also tell us about surface changes caused by space “weather,” such as radiation. The new color images reveal that the “heart” of Pluto actually consists of two remarkably different-colored regions. In the false-color image, the heart consists of a western lobe shaped like an ice cream cone that appears peach color in this image. A mottled area on the right (east) side looks bluish. A mid-latitude band appears in shades ranging from pale blue through red. Even within the northern polar cap, in the upper part of the image, various shades of yellow-orange indicate subtle compositional differences. This image was obtained using three of the color filters of the Ralph instrument on July 13 at 3:38 am EDT and received on the ground on at 12:25 pm. Charon is Just as Colorful The surface of Charon is viewed using the same exaggerated color. The red on the dark northern polar cap of Charon is attributed to hydrocarbon and other molecules, a class of chemical compounds called tholins. The mottled colors at lower latitudes point to the diversity of terrains on Charon. This image was obtained using three of the color filters of the Ralph instrument on July 13 at 3:38 am EDT and received on the ground on at 12:25 pm. “We make these color images to highlight the variety of surface environments present in the Pluto system,” said Dennis Reuter, co-investigator with the New Horizons Composition Team. “They show us in an intuitive way that there is much still to learn from the data coming down.” Due to the three-billion-mile distance to Pluto, data takes 4 ½ hours to come to Earth, even at the speed of light. It will take 16 months for all of New Horizons’ science data to be received, and the treasure trove from this mission will be studied for decades to come. Image Caption: Pluto and Charon in False Color Show Compositional Diversity This July 13, 2015, image of Pluto and Charon is presented in false colors to make differences in surface material and features easy to see. It was obtained by the Ralph instrument on NASA's New Horizons spacecraft, using three filters to obtain color information, which is exaggerated in the image. These are not the actual colors of Pluto and Charon, and the apparent distance between the two bodies has been reduced for this side-by-side view. The image reveals that the bright heart-shaped region of Pluto includes areas that differ in color characteristics. The western lobe, shaped like an ice-cream cone, appears peach color in this image. A mottled area on the right (east) appears bluish. Even within Pluto's northern polar cap, in the upper part of the image, various shades of yellow-orange indicate subtle compositional differences. The surface of Charon is viewed using the same exaggerated color. The red on the dark northern polar cap of Charon is attributed to hydrocarbon materials including a class of chemical compounds called tholins. The mottled colors at lower latitudes point to the diversity of terrains on Charon. --- At 7:49 AM EDT on Tuesday, July 14 New Horizons sped past Pluto at 30,800 miles per hour (49,600 kilometers per hour), with a suite of seven science instruments. As planned, New Horizons went incommunicado as it hurtled through the Pluto-Charon system busily gathering data. The New Horizons team will breathe a sigh of relief when New Horizons “phones home” at approximately 9:02 p.m. EDT on July 14. The mission to the icy dwarf planet completes the initial reconnaissance of the solar system. Stay in touch with the New Horizons mission with #PlutoFlyby and on Facebook at: www.facebook.com/new.horizons1

New objective of the "New Horizons" in the Kuiper belt

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.

2018-05-01

The scientific purpose of the study of the small planet 2014 MU69 is to obtain characteristics on its geology and morphology, to perform mapping of the surface composition: the search for ammonia, carbon monoxide, methane, water ice, etc. Also, it is planned to study its surface, the history of formation and development, measure the temperature, display the 3D topography in order to find out what it looks like, and by what it is differ, for example, from cometary nuclei, asteroids, dwarf planets, such as Pluto; search for any signs of activity, such as commas, to search for and explore possible satellites and / or rings, determine the mass, and so on. The spacecraft will visit MU69 1.01.2019. It is planned to get closer to its surface at a distance of about 3500 km. This will allow obtaining images of the surface with a resolution of up to 30 m.

Massive Smash-up at Vega Artist Concept

NASA Image and Video Library

2005-01-10

This artist concept illustrates how a massive collision of objects perhaps as large as the planet Pluto smashed together to create the dust ring around the nearby star Vega. New observations from NASA's Spitzer Space Telescope indicate the collision took place within the last one million years. Astronomers think that embryonic planets smashed together, shattered into pieces, and repeatedly crashed into other fragments to create ever finer debris. In the image, a collision is seen between massive objects that measured up to 2,000 kilometers (about 1,200 miles) in diameter. Scientists say the big collision initiated subsequent collisions that created dust particles around the star that were a few microns in size. Vega's intense light blew these fine particles to larger distances from the star, and also warmed them to emit heat radiation that can be detected by Spitzer's infrared detectors. http://photojournal.jpl.nasa.gov/catalog/PIA07217

New Horizons High-Phase Observations of Distant Kuiper Belt Objects

NASA Astrophysics Data System (ADS)

Verbiscer, A.; Porter, S.; Spencer, J. R.; Buie, M. W.; Benecchi, S.; Weaver, H. A., Jr.; Buratti, B. J.; Ennico Smith, K.; Olkin, C.; Stern, S. A.; Young, L. A.; Cheng, A. F.

2017-12-01

From its unique vantage point far from the Sun, NASA's New Horizons spacecraft has observed Kuiper Belt Objects at separations ranging from 0.1 to 70 AU, and at solar phase angles far larger than those attainable from Earth. We have constructed the first KBO solar phase curves with substantial phase angle coverage for targets including Haumea, Makemake, Quaoar, Arawn (Porter et al. 2016, Astrophys. J. Lett. 828, L15), and 2002 MS4. We compare the phase functions of these KBOs with those of objects in the Pluto system and other Solar System bodies such as comets, asteroids, and icy satellites. For KBOs with known geometric albedos, these measurements enable calculation of the phase integral, an important photometric property that characterizes the energy balance on a distant KBO surface. During its approach to 2014 MU69, and following its close encounter on 1 January 2019, New Horizons will continue to exploit its capabilities as NASA's only observatory within the Kuiper Belt itself.

Forecasting Weather on Distant Worlds

NASA Technical Reports Server (NTRS)

2007-01-01

An artist's conception shows a gas-giant planet orbiting very close to its parent star, creating searingly hot conditions on the planet's surface. New research suggests that for three such planets lying from 50 to 150 light-years from Earth, strong winds thousands of miles per hour mix the atmosphere so that the temperature is relatively uniform from the permanently light side to the permanently dark side.

This illustration represents an infrared view of a planetary system, in which brightness indicates warmer temperatures. For example, the bright band around the equator of the planet denotes warmer temperatures on both the dark and sunlit sides. The planet's poles, shown in darker colors, would be cooler.

A Dwarf Planet Class Object in the 21:5 Resonance with Neptune

NASA Astrophysics Data System (ADS)

Holman, Matthew J.; Payne, Matthew J.; Fraser, Wesley; Lacerda, Pedro; Bannister, Michele T.; Lackner, Michael; Chen, Ying-Tung; Lin, Hsing Wen; Smith, Kenneth W.; Kokotanekova, Rosita; Young, David; Chambers, K.; Chastel, S.; Denneau, L.; Fitzsimmons, A.; Flewelling, H.; Grav, Tommy; Huber, M.; Induni, Nick; Kudritzki, Rolf-Peter; Krolewski, Alex; Jedicke, R.; Kaiser, N.; Lilly, E.; Magnier, E.; Mark, Zachary; Meech, K. J.; Micheli, M.; Murray, Daniel; Parker, Alex; Protopapas, Pavlos; Ragozzine, Darin; Veres, Peter; Wainscoat, R.; Waters, C.; Weryk, R.

2018-03-01

We report the discovery of an H r = 3.4 ± 0.1 dwarf planet candidate by the Pan-STARRS Outer Solar System Survey. 2010 JO179 is red with (g ‑ r) = 0.88 ± 0.21, roughly round, and slowly rotating, with a period of 30.6 hr. Estimates of its albedo imply a diameter of 600–900 km. Observations sampling the span between 2005 and 2016 provide an exceptionally well determined orbit for 2010 JO179, with a semimajor axis of 78.307 ± 0.009 au; distant orbits known to this precision are rare. We find that 2010 JO179 librates securely within the 21:5 mean-motion resonance with Neptune on 100 Myr timescales, joining the small but growing set of known distant dwarf planets on metastable resonant orbits. These imply a substantial trans-Neptunian population that shifts between stability in high-order resonances, the detached population, and the eroding population of the scattering disk.

Solar system 'fast mission' trajectories using aerogravity assist

NASA Technical Reports Server (NTRS)

Randolph, James E.; Mcronald, Angus D.

1992-01-01

Initial analyses of the aerogravity assist (AGA) delivery technique to solar system targets (and beyond) has been encouraging. Mission opportunities are introduced that do not exist with typical gravity assist trajectories and current launch capabilities. The technique has the most payoff for high-energy missions such as outer planet orbiters and flybys. The goal of this technique is to reduce the flight duration significantly and to eliminate propulsion for orbit insertion. The paper will discuss detailed analyses and parametric studies that consider launch opportunities for missions to the sun, Saturn, Uranus, Neptune, and Pluto using AGA at Venus and Mars.

Origin and evolution of outer solar system atmospheres

NASA Technical Reports Server (NTRS)

Lunine, J. I.

1989-01-01

The origin and evolution of the atmospheres of bodies in the outer solar system is studied on the basis of the abundances of key molecular species. Formation models in which significant infall of icy and rocky planetesimals accompanies planet formation is supported by the enrichment of methane and deuterated species from Jupiter and Neptune. The chemistry of the solar nebula and Titan are discussed. The prospects for obtaining information on the atmosphere of Triton from the Voyager 2 mission are considered. It is found that the mean density of the Pluto-Charon system implies an origin in the rather water-poor solar nebula.

Variazioni di luminosità del pianeta Urano

NASA Astrophysics Data System (ADS)

Bianciardi, Giorgio

2005-04-01

This report describes R-CCD differential photometric studies of Uranus from 21 July 2004 through 18 September 2004. Results do not confirm the report by A. J. Hollis (2000) describing variations of magnitude of 0.3-0.5 over a 2 month period, and support the existence of brightness variations of some hundredths of a magnitude, in small (hours) and long (month) time scales. Uranus' appearance continues to change as it approaches its 2007 equinox, and even amateurs should dedicate particular attention to photometric evaluation of the planet. The same is true for Pluto, as it approaches its perihelion.

Mysterious Saturn--Some Ancient and Modern Views

ERIC Educational Resources Information Center

Agarwal, Pankaj

2011-01-01

The familiar image of Saturn and its rings has come to symbolise our idea of a planet but there is still much about Saturn and its system that we do not understand. The history of our beliefs and knowledge about it, one of the most distant planets visible to the naked eye, is described, from the early myths, such as the Indian village that…

The Light and Dark Sides of a Distant Planet

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] Poster Version

The top graph consists of infrared data from NASA's Spitzer Space Telescope. It tells astronomers that a distant planet, called Upsilon Andromedae b, always has a giant hot spot on the side that faces the star, while the other side is cold and dark. The artist's concepts above the graph illustrate how the planet might look throughout its orbit if viewed up close with infrared eyes.

Spitzer was able to determine the difference in temperature between the two sides of this planet by measuring the planet's infrared light, or heat, at five points during its 4.6-day-long trip around its star. The temperature rose and fell depending on which face, the sunlit or dark, was pointed toward Spitzer's cameras. Those temperature oscillations are traced by the wavy orange curve. They indicate that Upsilon Andromedae b has an extreme range of temperatures across its surface, about 1,400 degrees Celsius (2,550 degrees Fahrenheit). This means that hot gas moving across the bright side of the planet cools off by the time it reaches the dark side.

The bottom graph and artist's concepts represent what astronomers might have seen if the planet had bands of different temperatures girdling it, like Jupiter. Some astronomers had speculated that 'hot-Jupiter' planets like Upsilon Andromedae b, which circle very closely around their stars, might resemble Jupiter in this way. If Upsilon Andromedae b had been like this, there would have been no difference between the average temperatures of the sunlit and dark sides to detect, and Spitzer's data would have appeared as a flat line.

The Backyard Worlds: Planet 9 Citizen Science Project

NASA Astrophysics Data System (ADS)

Faherty, Jacqueline K.; Kuchner, Marc; Schneider, Adam; Meisner, Aaron; Gagné, Jonathan; Filippazzo, Joeseph; Trouille, Laura; Backyard Worlds: Planet 9 Collaboration; Jacqueline Faherty

2018-01-01

In February of 2017 our team launched a new citizen science project entitled Backyard Worlds: Planet 9 to scan the cosmos for fast moving stars, brown dwarfs, and even planets. This Zooniverse website, BackyardWorlds.org, invites anyone with a computer or smartphone to flip through WISE images taken over a several year baseline and mark any point source that appears to move. This “blinking technique” is the same that Clyde Tombaugh discovered Pluto with over 80 years ago. In the first few days of our program we recruited over 30,000 volunteers. After 3/4 of a year with the program we have completed 30% of the sky and our participants have identified several hundred candidate movers. These include (1) over 20 candidate Y-type brown dwarfs, (2) a handful of new co-moving systems containing a previously unidentified low mass object and a known nearby star, (3) over 100 previously missed M dwarfs, (4) and more than 200 candidate L and T brown dwarfs, many of which occupy outlier positions on reduced proper motion diagrams. Our first publication credited four citizen scientists as co-authors. The Backyard Worlds: Planet 9 project is both scientifically fruitful and empowering for any mind across the globe that has ever wanted to participate in a discovery-driven astronomy research project.

NASA’s Hubble Telescope Finds Potential Kuiper Belt Targets for New Horizons Pluto Mission

NASA Image and Video Library

2017-12-08

This is an artist’s impression of a Kuiper Belt object (KBO), located on the outer rim of our solar system at a staggering distance of 4 billion miles from the Sun. A HST survey uncovered three KBOs that are potentially reachable by NASA’s New Horizons spacecraft after it passes by Pluto in mid-2015. Credit: NASA, ESA, and G. Bacon (STScI) --- Peering out to the dim, outer reaches of our solar system, NASA’s Hubble Space Telescope has uncovered three Kuiper Belt objects (KBOs) the agency’s New Horizons spacecraft could potentially visit after it flies by Pluto in July 2015. The KBOs were detected through a dedicated Hubble observing program by a New Horizons search team that was awarded telescope time for this purpose. “This has been a very challenging search and it’s great that in the end Hubble could accomplish a detection – one NASA mission helping another,” said Alan Stern of the Southwest Research Institute (SwRI) in Boulder, Colorado, principal investigator of the New Horizons mission. The Kuiper Belt is a vast rim of primordial debris encircling our solar system. KBOs belong to a unique class of solar system objects that has never been visited by spacecraft and which contain clues to the origin of our solar system. The KBOs Hubble found are each about 10 times larger than typical comets, but only about 1-2 percent of the size of Pluto. Unlike asteroids, KBOs have not been heated by the sun and are thought to represent a pristine, well preserved deep-freeze sample of what the outer solar system was like following its birth 4.6 billion years ago. The KBOs found in the Hubble data are thought to be the building blocks of dwarf planets such as Pluto. Read more: 1.usa.gov/1vzUcyK NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Are Makemake and Eris Sputnik Planets?

NASA Astrophysics Data System (ADS)

Grundy, William M.; Umurhan, Orkan M.

2017-10-01

Makemake and Eris have high albedos (Sicardy et al. 2011; Ortiz et al. 2012) and show strong spectral absorption by CH4 ice (Licandro et al. 2006; Brown et al. 2007; Dumas et al. 2007). Energetic space radiation breaks C-H bonds in CH4 producing fragments that recombine into dark, red macromolecular materials (tholins, e.g., Johnson et al. 1987; Thompson et al. 1987; Strazzulla et al. 1991). This fact, coupled with Pluto's strong CH4 ice absorption bands and high albedo led Stern (1988) to pose the question "why is Pluto bright?". New Horizons has confirmed that Pluto refreshes its surface via seasonal volatile transport (e.g., Stern et al. 2015). However, one part of Pluto refreshes itself in a different way, too. This is the informally named Sputnik Planitia, a vast plain of volatile ice partly filling a probable impact basin. The ice is thick enough to act as a barrier to internal radiogenic heat flow, which drives convective overturning on 105 to 106 year timescales (e.g., McKinnon et al. 2016; Trowbridge et al 2016). Vigorous convection in Sputnik mixes radiolytic products from the surface down into the bulk of the ice, diluting it, and thus maintaining the high albedo of the surface.We propose that the surfaces of Eris and Makemake are similarly refreshed by convection in deep volatile ice deposits, perhaps covering the majority of their surfaces, unlike Pluto's Sputnik, which only covers a small fraction. The local fluxes of energetic radiation dictate production rates for tholin. Assuming steady-state production over the age of the solar system and mixing into the volatile ice, the colors and albedos of the bodies can be used to estimate the thickness of the volatile ice into which the tholin has been diluted through convective mixing. Likewise, for plausible radiogenic internal heat production, lower limits can be set on the thickness of the ice, to support convective mixing. We don't know the rheological properties of mixed N2+CH4 ice, let alone what happens when plausible additional contaminants, such as CO, Ar, C2H2, C2H4, C2H6, etc. are added, but bounding cases for N2-dominated and CH4-dominated ice compositions can be calculated.

Artificial Intelligence and NASA Data Used to Discover Eighth Planet Circling Distant Star

NASA Image and Video Library

2017-12-12

Our solar system now is tied for most number of planets around a single star, with the recent discovery of an eighth planet circling Kepler-90, a Sun-like star 2,545 light years from Earth. The planet was discovered in data from NASA’s Kepler space telescope. The newly-discovered Kepler-90i -- a sizzling hot, rocky planet that orbits its star once every 14.4 days -- was found by researchers from Google and The University of Texas at Austin using machine learning. Machine learning is an approach to artificial intelligence in which computers “learn.” In this case, computers learned to identify planets by finding in Kepler data instances where the telescope recorded signals from planets beyond our solar system, known as exoplanets. Video Credit: NASA Ames Research Center / Google

Looking for planetary moons in the spectra of distant Jupiters.

PubMed

Williams, D M; Knacke, R F

2004-01-01

More than 100 nearby stars are known to have at least one Jupiter-sized planet. Whether any of these giant gaseous planets has moons is unknown, but here we suggest a possible way of detecting Earth-sized moons with future technology. The planned Terrestrial Planet Finder observatory, for example, will be able to detect objects comparable in size to Earth. Such Earth-sized objects might orbit their stars either as isolated planets or as moons to giant planets. Moons of Jovian-sized planets near the habitable zones of main-sequence stars should be noticeably brighter than their host planets in the near-infrared (1-4 microm) if their atmospheres contain methane, water, and water vapor, because of efficient absorption of starlight by these atmospheric components. By taking advantage of this spectral contrast, future space observatories will be able to discern which extrasolar giant planets have Earth-like moons capable of supporting life.

Introducing GV : The Spacecraft Geometry Visualizer

NASA Astrophysics Data System (ADS)

Throop, Henry B.; Stern, S. A.; Parker, J. W.; Gladstone, G. R.; Weaver, H. A.

2009-12-01

GV (Geometry Visualizer) is a web-based program for planning spacecraft observations. GV is the primary planning tool used by the New Horizons science team to plan the encounter with Pluto. GV creates accurate 3D images and movies showing the position of planets, satellites, and stars as seen from an observer on a spacecraft or other body. NAIF SPICE routines are used throughout for accurate calculations of all geometry. GV includes 3D geometry rendering of all planetary bodies, lon/lat grids, ground tracks, albedo maps, stellar magnitudes, types and positions from HD and Tycho-2 catalogs, and spacecraft FOVs. It generates still images, animations, and geometric data tables. GV is accessed through an easy-to-use and flexible web interface. The web-based interface allows for uniform use from any computer and assures that all users are accessing up-to-date versions of the code and kernel libraries. Compared with existing planning tools, GV is often simpler, faster, lower-cost, and more flexible. GV was developed at SwRI to support the New Horizons mission to Pluto. It has been subsequently expanded to support multiple other missions in flight or under development, including Cassini, Messenger, Rosetta, LRO, and Juno. The system can be used to plan Earth-based observations such as occultations to high precision, and was used by the public to help plan 'Kodak Moment' observations of the Pluto system from New Horizons. Potential users of GV may contact the author for more information. Development of GV has been funded by the New Horizons, Rosetta, and LRO missions.

An estimate of the prevalence of biocompatible and habitable planets.

PubMed

Fogg, M J

1992-01-01

A Monte Carlo computer model of extra-solar planetary formation and evolution, which includes the planetary geochemical carbon cycle, is presented. The results of a run of one million galactic disc stars are shown where the aim was to assess the possible abundance of both biocompatible and habitable planets. (Biocompatible planets are defined as worlds where the long-term presence of surface liquid water provides environmental conditions suitable for the origin and evolution of life. Habitable planets are those worlds with more specifically Earthlike conditions). The model gives an estimate of 1 biocompatible planet per 39 stars, with the subset of habitable planets being much rarer at 1 such planet per 413 stars. The nearest biocompatible planet may thus lie approximately 14 LY distant and the nearest habitable planet approximately 31 LY away. If planets form in multiple star systems then the above planet/star ratios may be more than doubled. By applying the results to stars in the solar neighbourhood, it is possible to identify 28 stars at distances of < 22 LY with a non-zero probability of possessing a biocompatible planet.

Interplanetary missions with the GDM propulsion system

NASA Astrophysics Data System (ADS)

Kammash, T.; Emrich, W.

1998-01-01

The Gasdynamic Mirror (GDM) fusion propulsion system utilizes a magnetic mirror machine in which a hot dense plasma is confined long enough to produce fusion energy while allowing a fraction of its charged particle population to escape from one end to generate thrust. The particles escaping through the opposite end have their energy converted to electric power which can be used to sustain the system in a steady state operation. With the aid of a power flow diagram the minimum demands on energy production can be established and the propulsive capability of the system can be determined by solving an appropriate set of governing equations. We apply these results to several missions within the solar system and compute the trip time by invoking a continuous burn, acceleration/deceleration type of trajectory with constant thrust and specific impulse. Ignoring gravitational effects of the planets or the sun, and neglecting the change in the Earth's position during the flight we compute the round trip time for missions from Earth to Mars, Jupiter, and Pluto using linear distances and certain payload fractions. We find that a round trip to Mars with the GDM rocket takes about 170 days while those to Jupiter and Pluto take 494 and 1566 days respectively.

Not So Titanic

NASA Image and Video Library

2015-07-13

Titan may be a "large" moon -- its name even implies it! -- but it is still dwarfed by its parent planet, Saturn. As it turns out, this is perfectly normal. Although Titan (3200 miles or 5150 kilometers across) is the second-largest moon in the solar system, Saturn is still much bigger, with a diameter almost 23 times larger than Titan's. This disparity between planet and moon is the norm in the solar system. Earth's diameter is "only" 3.7 times our moon's diameter, making our natural satellite something of an oddity. (Another exception to the rule: dwarf planet Pluto's diameter is just under two times that of its moon.) So the question isn't why is Titan so small (relatively speaking), but why is Earth's moon so big? This view looks toward the anti-Saturn hemisphere of Titan. North on Titan is up. The image was taken with the Cassini spacecraft wide-angle camera on April 18, 2015 using a near-infrared spectral filter with a passband centered at 752 nanometers. The view was acquired at a distance of approximately 930,000 miles (1.5 million kilometers) from Titan. Image scale is 56 miles (90 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18326

Dynamical and observational constraints on satellites in the inner Pluto-Charon system

NASA Technical Reports Server (NTRS)

Stern, S. Alan; Parker, Joel William; Duncan, Martin J.; Snowdall, J. Clark, Jr.; Levison, Harold F.

1994-01-01

It is not known if Pluto has other satellites besides its massive partner Charon. In the past, searches for additional satellites in the Pluto-Charon system have extended from the solar-tidal stability boundary (approximately 90 arcsec from Pluto) inward to about 1 arcsec from Pluto. Here we further explore the inner (i.e., less than 10 arcsec) region of the Pluto-Charon system to determine where additional satellites might lie. In particular, we report on (1) dynamical simulations to delineate the region where unstable orbits lie around Charon, (2) dynamical simulations which use the low orbital eccentricity of Charon to constrain the mass of any third body near Pluto, and (3) analysis of Hubble Space Telescope (HST) archival images to search for satellites in the inner Pluto-Charon system. Although no objects were found, significant new constraints on bodies orbiting in the inner Pluto-Charon system were obtained.

A Full View of Pluto Stunning Crescent

NASA Image and Video Library

2015-10-29

In September, NASA's New Horizons team released a stunning but incomplete image of Pluto's crescent. Thanks to new processing work by the science team, New Horizons is releasing the entire, breathtaking image of Pluto. This image was made just 15 minutes after New Horizons' closest approach to Pluto on July 14, 2015, as the spacecraft looked back at Pluto toward the sun. The wide-angle perspective of this view shows the deep haze layers of Pluto's atmosphere extending all the way around Pluto, revealing the silhouetted profiles of rugged plateaus on the night (left) side. The shadow of Pluto cast on its atmospheric hazes can also be seen at the uppermost part of the disk. On the sunlit side of Pluto (right), the smooth expanse of the informally named icy plain Sputnik Planum is flanked to the west (above, in this orientation) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. Below (east) of Sputnik, rougher terrain is cut by apparent glaciers. The backlighting highlights more than a dozen high-altitude layers of haze in Pluto's tenuous atmosphere. The horizontal streaks in the sky beyond Pluto are stars, smeared out by the motion of the camera as it tracked Pluto. The image was taken with New Horizons' Multi-spectral Visible Imaging Camera (MVIC) from a distance of 11,000 miles (18,000 kilometers) to Pluto. The resolution is 700 meters (0.4 miles).

First results of MAO NASU SS bodies photographic archive digitizing

NASA Astrophysics Data System (ADS)

Pakuliak, L.; Andruk, V.; Shatokhina, S.; Golovnya, V.; Yizhakevych, O.; Kulyk, I.

2013-05-01

MAO NASU glass archive encloses about 1800 photographic plates with planets and their satellites (including near 80 images of Uranus, Pluto and Neptune), about 1700 plates with minor planets and about 900 plates with comets. Plates were made during 1949-1999 using 11 telescopes of different focus, mostly the Double Wide-angle Astrograph (F/D=2000/400) and the Double Long-focus Astrograph (F/D=5500/400) of MAO NASU. Observational sites are Kyiv, Lviv (Ukraine), Biurakan (Armenia), Abastumani (Georgia), Mt. Maidanak (Uzbekistan), Quito (Equador). Tables contain data about the most significant numbers of plates sub-divided by years and objects. The database with metadata of plates (DBGPA) is available on the computer cluster of MAO (http://gua.db.ukr-vo.org) via open access. The database accumulates archives of four Ukrainian observatories, involving the UkrVO national project. Together with the archive managing system, the database serves as a test area for JDA - Joint Digital Archive - the core of the UkrVO.

Optimum solar electric interplanetary mission opportunities from 1975 to 1990

NASA Technical Reports Server (NTRS)

Mann, F. I.; Horsewood, J. L.

1971-01-01

A collection of optimum trajectory and spacecraft data is presented for unmanned interplanetary missions from 1975 to 1990 using solar electric propulsion. Data are presented for one-way flyby and orbiter missions from Earth to Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. The solar system model assumes planetary ephemerides which very closely approximate the true motion of the planets. Direct and indirect flight profiles are investigated. Data are presented for two representative flight times for each mission. The launch vehicle is the Titan 3 B (core)/Centaur, and a constant jet exhaust speed solar electric propulsion system having a specific mass of 30 kg/kw is completely optimized in terms of power level and jet exhaust speed to yield maximum net spacecraft mass. The hyperbolic excess speeds at departure and arrival and the launch date are optimized for each mission. For orbiter missions, a chemical retro stage is used to brake the spacecraft into a highly eccentric capture orbit about the target planet.

MOLECULAR-KINETIC SIMULATIONS OF ESCAPE FROM THE EX-PLANET AND EXOPLANETS: CRITERION FOR TRANSONIC FLOW

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Robert E.; Volkov, Alexey N.; Erwin, Justin T.

The equations of gas dynamics are extensively used to describe atmospheric loss from solar system bodies and exoplanets even though the boundary conditions at infinity are not uniquely defined. Using molecular-kinetic simulations that correctly treat the transition from the continuum to the rarefied region, we confirm that the energy-limited escape approximation is valid when adiabatic expansion is the dominant cooling process. However, this does not imply that the outflow goes sonic. Rather large escape rates and concomitant adiabatic cooling can produce atmospheres with subsonic flow that are highly extended. Since this affects the heating rate of the upper atmosphere andmore » the interaction with external fields and plasmas, we give a criterion for estimating when the outflow goes transonic in the continuum region. This is applied to early terrestrial atmospheres, exoplanet atmospheres, and the atmosphere of the ex-planet, Pluto, all of which have large escape rates.« less

The Dynamical Imprint of Lost Protoplanets on the Trans-Neptunian Populations, and Limits on the Primordial Size Distribution of Trans-Neptunian Objects at Pluto and Larger Sizes.

NASA Astrophysics Data System (ADS)

Shannon, Andrew Brian; Dawson, Rebekah

2018-04-01

Planet formation remains a poorly understood process, in part because of our limited access to the intermediate phases of planetesimal and protoplanet growth. Today, the vast majority of the accessible remaining planetesimals and protoplanets reside within the Hot Trans-Neptunian Object population. This population has been depleted by 99% - 99.9% over the course of the Solar system's history, and as such the present day size-number distribution may be incomplete at the large size end. We show that such lost protoplanets would have left signatures in the dynamics of the present-day Trans-Neptunian Populations, and their primordial number can thus be statistically limited by considering the survival of ultra-wide binary TNOs, the Cold Classical Kuiper belt, and the resonant populations. We compare those limits to the predicted size-number distribution of various planetesimal and proto-planet growth models.

Outer planets satellites

NASA Technical Reports Server (NTRS)

Morrison, D.

1983-01-01

The present investigation takes into account the published literature on outer planet satellites for 1979-1982. It is pointed out that all but three (the moon and the two Martian satellites) of the known planetary satellites are found in the outer solar system. Most of these are associated with the three regular satellite systems of Jupiter, Saturn, and Uranus. The largest satellites are Titan in the Saturn system and Ganymede and Callisto in the Jupiter system. Intermediate in size between Mercury and Mars, each has a diameter of about 5000 km. Presumably each has an internal composition about 60 percent rock and 40 ice, and each is differentiated with a dense core extending out about 75 percent of the distance to the surface, with a mantle of high-pressure ice and a crust of ordinary ice perhaps 100 km thick. Attention is also given to Io, Europa, the icy satellites of Saturn, the satellites of Uranus, the small satellites of Jupiter and Saturn, Triton and the Pluto system, and plans for future studies.

Adaptive Nulling for Interferometric Detection of Planets

NASA Technical Reports Server (NTRS)

Lay, Oliver P.; Peters, Robert D.

2010-01-01

An adaptive-nulling method has been proposed to augment the nulling-optical- interferometry method of detection of Earth-like planets around distant stars. The method is intended to reduce the cost of building and aligning the highly precise optical components and assemblies needed for nulling. Typically, at the mid-infrared wavelengths used for detecting planets orbiting distant stars, a star is millions of times brighter than an Earth-sized planet. In order to directly detect the light from the planet, it is necessary to remove most of the light coming from the star. Nulling interferometry is one way to suppress the light from the star without appreciably suppressing the light from the planet. In nulling interferometry in its simplest form, one uses two nominally identical telescopes aimed in the same direction and separated laterally by a suitable distance. The light collected by the two telescopes is processed through optical trains and combined on a detector. The optical trains are designed such that the electric fields produced by an on-axis source (the star) are in anti-phase at the detector while the electric fields from the planet, which is slightly off-axis, combine in phase, so that the contrast ratio between the star and the planet is greatly decreased. If the electric fields from the star are exactly equal in amplitude and opposite in phase, then the star is effectively nulled out. Nulling is effective only if it is complete in the sense that it occurs simultaneously in both polarization states and at all wavelengths of interest. The need to ensure complete nulling translates to extremely tight demands upon the design and fabrication of the complex optical trains: The two telescopes must be highly symmetric, the reflectivities of the many mirrors in the telescopes and other optics must be carefully tailored, the optical coatings must be extremely uniform, sources of contamination must be minimized, optical surfaces must be nearly ideal, and alignments must be extremely precise. Satisfaction of all of these requirements entails substantial cost.

Discovery, Orbit and Orbital Evolution of the Distant Object (463368) 2012 VU85

NASA Astrophysics Data System (ADS)

Wlodarczyk, I.; Černis, K.; Boyle, R. P.

2017-03-01

We present the discovery and time evolution of orbital elements of the distant Centaur-type object (463368) 2012 VU85. From all 2135 distant objects listed in the Minor Planet Center we select all 347 numbered distant object and integrate their equations of motion in the 1 Gyr forward and backward integration. The asteroid (463368) 2012 VU85 lies on the border of the group of 347 distant objects, which have a semimajor axis about 44 a.u., eccentricity 0.1 and inclination between 0° and 30°. We show that after 1 Gyr of forward integration, about half of the objects are expelled from the Solar System, \\ie their median lifetime is about 1 Gyr. We note that the long-lived distant objects are mainly located between the regions where Neptune controls aphelia of asteroids and the asteroids are in the mean motion resonance 2/3 with Neptune. We find eight almost regular approaches of clones of the asteroid (463368) 2012 VU85 to Neptune and several generally shorter in time regular approaches to Uranus. For other outer planets we did not detect any approaches below 5 a.u. for a period of 15 000 yr in forward and backward integrations. In our calculations we find eight episodes, each lasting about 3000 yr when the value of inclination oscillates around its average. These changes look similar to the changes of semimajor axis during the occurrence of orbital mean motion resonance with a planet. We find that half of the clones of the asteroid (463368) 2012 VU85 remain in the Solar System for a forward integration of 44 Myr, and for a backward integration of 34 Myr. This is a significantly shorter escape time as compared to the group of distant objects. Almost all long-lived clones have value of Tisserand parameter with respect to Neptune smaller than 3 during the whole 1 Gyr forward and backward integrations. This implies that there are several clones of the asteroid (463368) 2012 VU85 that cross the orbits of Neptune and Uranus. We find many orbital mean motion resonances lasting up to several Myr in the motion of the asteroid (463368) 2012 VU85. According to our computations the presence of the Kozai resonance protects the asteroid from the close approaches with Uranus and Neptune. The Lyapunov time for the asteroid (463368) 2012 VU85 is equal to 4260 years.

What Eating at Pluto?

NASA Image and Video Library

2016-03-10

Scientists on NASA's New Horizons mission have discovered what looks like a giant bite-mark on the planet's surface. In this image, north is up. The southern portion of the left inset above shows the cratered plateau uplands informally named Vega Terra (note that all feature names are informal). This terrain is separated from the young, nearly uncratered, mottled plains of Piri Planitia in the center of the image by a generally north-facing jagged scarp called Piri Rupes. The scarp breaks up into isolated mesas in several places. Cutting diagonally across Piri Planitia is the long extensional fault of Inanna Fossa, which stretches eastward 370 miles (600 kilometers) from here to the western edge of the great nitrogen ice plains of Sputnik Planum. Compositional data from the New Horizons spacecraft's Ralph/Linear Etalon Imaging Spectral Array (LEISA) instrument, shown in the right inset, indicate that the plateau uplands south of Piri Rupes are rich in methane ice (shown in false color as purple). Scientists speculate that sublimation of methane may be causing the plateau material to erode along the face of the scarp cliffs, causing them to retreat south and leave the plains of Piri Planitia in their wake. Compositional data also show that the surface of Piri Planitia is more enriched in water ice (shown in false color as blue) than the plateau uplands, which may indicate that Piri Planitia's surface is made of water ice bedrock, on top of which the layer of retreating methane ice had been sitting. Because the surface of Pluto is so cold, the water ice behaves like rock and is immobile. The light/dark mottled pattern of Piri Planitia in the left inset is reflected in the composition map, with the lighter areas corresponding to areas richer in methane – these may be remnants of methane that have not yet sublimated away entirely. The inset at left shows about 650 feet (200 meters) per pixel; the image measures approximately 280 miles (450 kilometers) long by 255 miles (410 kilometers) wide. It was obtained by New Horizons at a range of approximately 21,100 miles (33,900 kilometers) from Pluto, about 45 minutes before the spacecraft's closest approach to Pluto on July 14, 2015.The LEISA data at right was gathered when the spacecraft was about 29,000 miles (47,000 kilometers) from Pluto; best resolution is 1.7 miles (2.7 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA20531

Pushing back the frontier - A mission to the Pluto-Charon system

NASA Technical Reports Server (NTRS)

Farquhar, Robert; Stern, S. Alan

1990-01-01

A flyby mission to Pluto is proposed. The size, orbit, atmosphere, and surface of Pluto, and the Pluto-Charon system are described. The benefits of a planetary flyby compared to ground observations are discussed in terms of imaging capabilities. Planned payloads include a plasma science package, a UV spectrometer, and a thermal mapper. The advantages of a dual launch to Mars and the need for a Jupiter-Pluto transfer are considered. A diagram of a spacecraft for a flyby study of Pluto is provided.

Upcoming and Future Missions in the Area of Infrared Astronomy: Spacecraft and Ground-based Observations

NASA Technical Reports Server (NTRS)

Sittler, E. C., Jr.

2004-01-01

The IRIS instrument on the Voyager spacecrafts made major discoveries with regard to the giant planets, their moons and rings and paved the way for future infrared observations for planetary missions within our solar system. The CIRS instrument of Cassini with much greater spectral-spatial resolution and sensitivity than that provided by IRIS is now rapidly approaching the Saturnian system with orbit insertion on July 1, 2004, for which CIRS is expected to provide an order of magnitude advance beyond that provided by IRIS. The Mars program is also presently dominated by infrared observations in the near to mid-infrared spectral bands for missions such as Mars Global Surveyor and its TES instrument and Odyssey with its THEMIS instrument. In the case of Earth science we have such missions as TIMED, which makes infrared observations of the thermosphere using the SABER instrument. With the newly formed New Frontiers Program we have the opportunity for $650M missions such as Kuiper Belt-Pluto Explorer and Jupiter Polar Orbiter with Probes. Under the Flagship line, once per decade, we have the opportunity for $1B missions for which Europa is presently being considered; for this mission infrared measurements could look for hot spots within the maze of cracks and faults on Europa s surface. On Kuiper Belt- Pluto there is an imaging near-IR spectrometer called LEISA. Another mission on the horizon is Titan Orbiter Aerorover Mission (TOAM) for which there is planned a state-of-art version of CIRS called TIRS on the orbiter that will map out the atmospheric composition with unprecedented wavelength coverage and spectral-spatial resolution. This instrument will also provide temperature maps of the surface of Titan to look for hot spots where life may form. On the same mission there will be a descent imager on the Aerorover (i.e., balloon) similar to that provided by LEISA on the Pluto mission to provide compositional-topographical maps of Titan s surface. Other future mission will also be discussed. Improved thermal detectors could have important applications in solar physics, specifically in the detection of far-IR synchrotron emission from energetic electrons in solar flares. For infrared astronomy we have missions like SIRTF and JWST, which will cover the spectral range from near-IR to far-IR in the search and probing of both new and old planetary systems in our galaxy and the measurement of the most distant galaxies of our universe. SIRTF is scheduled to be launched in August 2003, while JWST will be launched next decade. Another mission is TPF, which will use interferometer techniques at infrared wavelengths to search for planetary systems beyond 2010. With regard to ground based telescopes we have, for example, the twin 10 meter Keck telescopes and the IRTF telescope at Mauna Kea. The Keck telescopes are presently using interferometer techniques. Over the next several decades there are plans for 50 meter to 200 meter telescopes providing near-IR to far-IR measurements with the eventual plan to combine all telescopes using interferometer techniques to provide unprecedented spectral-spatial resolution and sensitivity.

Pluto's atmosphere in 2015 from high-resolution spectroscopy

NASA Astrophysics Data System (ADS)

Roe, Henry G.; Cook, Jason C.; Mace, Gregory N.; Holler, Bryan J.; Young, Leslie A.; McLane, Jacob N.; Jaffe, Daniel T.

2015-11-01

Pluto's thin N2/CH4 atmosphere is in vapor-pressure equilibrium with ices on its surface. The atmosphere evolves seasonally with the varying insolation pattern on Pluto's heterogenous surface, perhaps even largely freezing out to the surface during the coldest portion of Pluto's year. We use high-resolution (R≈25,000-50,000) near-infrared spectroscopy to resolve atmospheric methane absorption lines from Pluto's continuum spectra, as well as separate Pluto's atmospheric lines from the telluric spectrum. In addition to measuring the abundance and temperature of Pluto's atmospheric CH4, with broad wavelength coverage we are able to search for the inevitable products of N2/CH4 photochemistry. In 2015 we are undertaking an intensive campaign using NIRSPEC at Keck Observatory and IGRINS (Immersion Grating INfrared Spectrometer) at McDonald Observatory to coincide with the New Horizons Pluto encounter. We will report initial results from this 2015 campaign and compare the state of Pluto's atmosphere at the time of the New Horizons encounter with earlier years.

Hydrothermal systems in small ocean planets.

PubMed

Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael

2007-12-01

We examine means for driving hydrothermal activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of hydrothermal system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of hydrothermal activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive hydrothermal fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive hydrothermal circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1).

Mass-radius relationships and constraints on the composition of Pluto

NASA Technical Reports Server (NTRS)

Lupo, M. J.; Lewis, J. S.

1980-01-01

With the new upper limit of Pluto's mass, an upper limit for Pluto's density of 1.74 g/cu cm has been found. Assuming Pluto to be 100% methane, available methane density data can be used to set a lower limit of 0.53 g/cu cm on Pluto's density, thus placing an absolute upper limit of 1909 km on the radius and a lower limit of 0.32 on the albedo. The results of 280 computer models covering a wide range of composition ratios of rock, water ice, and methane ice are reported. Limits are placed on Pluto's silicate content, and a simple spacecraft method for determining Pluto's water content from its density and moment of inertia is given. The low thermal conductivity and strength of solid methane suggest rapid solid-state convection in Pluto's methane layer.

Prevalence and Properties of Planets from Kepler and K2

NASA Astrophysics Data System (ADS)

Petigura, Erik; Marcy, Geoffrey W.; Howard, Andrew; Crossfield, Ian; Beichman, Charles; Sinukoff, Evan

2015-12-01

Discoveries from the prime Kepler mission demonstrated that small planets (< 3 Earth-radii) are common outcomes of planet formation around G, K, and M stars. While Kepler detected many such planets, all but a handful orbit faint, distant stars, which are not amenable to precise follow up measurements. NASA's K2 mission has the potential to increase the number of known small, transiting planets around bright stars by an order of magnitude. I will present the latest results from my team's efforts to detect, confirm, and characterize planets using the K2 mission. I will highlight some of the progress and remaining challenges involved with generating denoised K2 photometry and with detecting planets in the presence of severe instrument systematics. Among our recent discoveries are the K2-3 and K2-21 planetary systems: M dwarfs hosting multiple transiting Earth-size planets with low equilibrium temperatures. These systems offer a convenient laboratory for studying the bulk composition and atmospheric properties of small planets receiving low levels of stellar irradiation, where processes such as mass loss by photo-evaporation could play a weaker role.

PSF subtraction to search for distant Jupiters with SPITZER

NASA Astrophysics Data System (ADS)

Rameau, Julien; Artigau, Etienne; Baron, Frédérique; Lafrenière, David; Doyon, Rene; Malo, Lison; Naud, Marie-Eve; Delorme, Philippe; Janson, Markus; Albert, Loic; Gagné, Jonathan; Beichman, Charles

2015-12-01

In the course of the search for extrasolar planets, a focus has been made towards rocky planets very close (within few AUs) to their parent stars. However, planetary systems might host gas giants as well, possibly at larger separation from the central star. Direct imaging is the only technique able to probe the outer part of planetary systems. With the advent of the new generation of planet finders like GPI and SPHERE, extrasolar systems are now studied at the solar system scale. Nevertheless, very extended planetary systems do exist and have been found (Gu Ps, AB Pic b, etc.). They are easier to detect and characterize. They are also excellent proxy for close-in gas giants that are detected from the ground. These planets have no equivalent in our solar system and their origin remain a matter of speculation. In this sense, studying planetary systems from its innermost to its outermost part is therefore mandatory to have a clear understanding of its architecture, hence hints of its formation and evolution. We are carrying out a space-based survey using SPITZER to search for distant companions around a well-characterized sample of 120 young and nearby stars. We designed an observing strategy that allows building a very homogeneous PSF library. With this library, we perform a PSF subtraction to search for planets from 10’’ down to 1’’. In this poster, I will present the library, the different algorithms used to subtract the PSF, and the promising detection sensitivity that we are able to reach with this survey. This project to search for the most extreme planetary systems is unique in the exoplanet community. It is also the only realistic mean of directly imaging and subsequently obtaining spectroscopy of young Saturn or Jupiter mass planets in the JWST-era.

Pluto Color Map

NASA Image and Video Library

2017-01-20

This new, detailed global mosaic color map of Pluto is based on a series of three color filter images obtained by the Ralph/Multispectral Visual Imaging Camera aboard New Horizons during the NASA spacecraft's close flyby of Pluto in July 2015. The mosaic shows how Pluto's large-scale color patterns extend beyond the hemisphere facing New Horizons at closest approach- which were imaged at the highest resolution. North is up; Pluto's equator roughly bisects the band of dark red terrains running across the lower third of the map. Pluto's giant, informally named Sputnik Planitia glacier - the left half of Pluto's signature "heart" feature -- is at the center of this map. http://photojournal.jpl.nasa.gov/catalog/PIA11707

Pluto in Hi-Def Note: There is debate within the science community as to whether Pluto should be

NASA Technical Reports Server (NTRS)

2008-01-01

This image demonstrates the first detection of Pluto using the high-resolution mode on the New Horizons Long-Range Reconnaissance Imager (LORRI). The mode provides a clear separation between Pluto and numerous nearby background stars. When the image was taken on October 6, 2007, Pluto was located in the constellation Serpens, in a region of the sky dense with background stars.

Typically, LORRI's exposure time in hi-res mode is limited to approximately 0.1 seconds, but by using a special pointing mode that allowed an increase in the exposure time to 0.967 seconds, scientists were able to spot Pluto, which is approximately 15,000 times fainter than human eyes can detect.

New Horizons was still too far from Pluto (3.6 billion kilometers, or 2.2 billion miles) for LORRI to resolve any details on Pluto's surface that won't happen until summer 2014, approximately one year before closest approach. For now the entire Pluto system remains a bright dot to the spacecraft's telescopic camera, though LORRI is expected to start resolving Charon from Pluto seeing them as separate objects in summer 2010.

Searching for New Earths: Teaching Children How We Seek Distant Planets

NASA Astrophysics Data System (ADS)

Pulliam, C.

2008-06-01

Teaching science to children ages 8-13 can be a great challenge, especially if you lack the resources for a full-blown audio/visual presentation. How do you hold their attention and get them involved? One method is to teach a topic no one else covers at this educational level: something exciting and up-to-the-minute, at the cutting edge of science. We developed an interactive 45-minute presentation to convey the two basic techniques used to locate planets orbiting other stars. Activities allowed children to hunt for their own planets in simulated data sets. We also stimulated their imagination by giving each child a take-home, multicolored marble ``planet'' and asking them to discuss their planet's characteristics. The resulting presentation ``Searching for New Earths'' could be adapted to a variety of educational settings.

Energetic Particles in the far and near Environment of Pluto

NASA Astrophysics Data System (ADS)

Kollmann, P.; Hill, M. E.; McNutt, R. L., Jr.; Brown, L. E.; Kusterer, M. B.; Vandegriff, J. D.; Smith, H. T.; Mitchell, D. G.; Haggerty, D. K.; Bagenal, F.; Krimigis, S. M.; Lisse, C. M.; Delamere, P. A.; Elliott, H. A.; Horanyi, M.; McComas, D. J.; Piquette, M. R.; Poppe, A. R.; Sidrow, E. J.; Strobel, D. F.; Szalay, J.; Valek, P. W.; Weidner, S.; Zirnstein, E.; Ennico Smith, K.; Olkin, C.; Weaver, H. A., Jr.; Young, L. A.; Stern, A.

2015-12-01

The New Horizons spacecraft was launched in 2006, passed Jupiter and its magnetotail, took continuous measurements in the solar wind throughout the recent years, and flew by Pluto in July 2015. The onboard PEPSSI instrument measures ion and electron intensities, masses, and energies in the keV to MeV range. The closest approach distance to Pluto was 11 Pluto radii, inside the orbit of Charon. Data taken near Pluto is downlinked throughout August. We will present analysis of this data and set it into context with previous measurements. We expect a number of interesting particle structures around Pluto. Parts of Pluto's molecular nitrogen atmosphere is escaping and will co-orbit with Pluto, potentially forming a partial gas torus. This torus can be additionally sourced by other Kuiper belt objects. The neutrals are eventually ionized and pick-up by the solar wind brings them into the PEPSSI energy range. The measured ion densities can be used to constrain the Pluto torus. Pluto is not expected to have an intrinsic magnetic field, but the energetic particle data can be used to infer its properties, if any. Pluto interacts instead with the solar wind via the pick-up of its ions and the magnetic fields created by currents in its ionosphere. The relative role of these mechanisms can be revealed by the flyby data and directly compared to data that was taken at Jupiter with identical instrumentation.

Faces of Pluto

NASA Image and Video Library

2015-06-11

These images, taken by NASA's New Horizons' Long Range Reconnaissance Imager (LORRI), show four different "faces" of Pluto as it rotates about its axis with a period of 6.4 days. All the images have been rotated to align Pluto's rotational axis with the vertical direction (up-down) on the figure, as depicted schematically in the upper left. From left to right, the images were taken when Pluto's central longitude was 17, 63, 130, and 243 degrees, respectively. The date of each image, the distance of the New Horizons spacecraft from Pluto, and the number of days until Pluto closest approach are all indicated in the figure.These images show dramatic variations in Pluto's surface features as it rotates. When a very large, dark region near Pluto's equator appears near the limb, it gives Pluto a distinctly, but false, non-spherical appearance. Pluto is known to be almost perfectly spherical from previous data. These images are displayed at four times the native LORRI image size, and have been processed using a method called deconvolution, which sharpens the original images to enhance features on Pluto. Deconvolution can occasionally introduce "false" details, so the finest details in these pictures will need to be confirmed by images taken from closer range in the next few weeks. All of the images are displayed using the same brightness scale. http://photojournal.jpl.nasa.gov/catalog/PIA19686

Possible occultation by Pluto from US East Coast

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2012-06-01

We have been asked to help disseminate the news of a possible occultation by Pluto visible to observers on the US East coast. Although the AAVSO does not ordinarily issue announcements of upcoming occultations, in this case the object is Pluto and the NASA New Horizons mission (http://www.nasa.gov/mission_pages/newhorizons/main/index.html) will be visiting Pluto in 2015. The information below has been supplied by Dr. Leslie Young (Southwest Research Institute), who is coordinating this observing campaign on Pluto. Dr. Young is also Deputy Project Scientist for the New Horizons mission. ALERT: Possible Pluto occultation Wednesday night (2012/06/14 03:28 UT) from US East coast. CONTACT: Leslie Young (layoung@boulder.swri.edu; work: 303-546-6057; skype: drpluto). Also see our planning pages in progress at http://wiki.boulder.swri.edu/mediawiki/index.php/2012-06-14_Pluto_occultation. Pluto's thin, nitrogen atmosphere is in vapor-pressure equilibrium with the surface ice, and changes seasonally. We've seen it double since 1988, and now we measure its pressure once or twice a year. The technique we use is stellar occultation, when a star passes behind Pluto's atmosphere. The atmosphere defocuses the starlight. By the timing of the fading of the star, we measure the pressure and temperature in Pluto's atmosphere at ~10 km resolution. MORE INFORMATION: See http://wiki.boulder.swri.edu/mediawiki/index.php/2012-06-14_Pluto_occultation.

Simulating the escaping atmospheres of hot gas planets in the solar neighborhood

NASA Astrophysics Data System (ADS)

Salz, M.; Czesla, S.; Schneider, P. C.; Schmitt, J. H. M. M.

2016-02-01

Absorption of high-energy radiation in planetary thermospheres is generally believed to lead to the formation of planetary winds. The resulting mass-loss rates can affect the evolution, particularly of small gas planets. We present 1D, spherically symmetric hydrodynamic simulations of the escaping atmospheres of 18 hot gas planets in the solar neighborhood. Our sample only includes strongly irradiated planets, whose expanded atmospheres may be detectable via transit spectroscopy using current instrumentation. The simulations were performed with the PLUTO-CLOUDY interface, which couples a detailed photoionization and plasma simulation code with a general MHD code. We study the thermospheric escape and derive improved estimates for the planetary mass-loss rates. Our simulations reproduce the temperature-pressure profile measured via sodium D absorption in HD 189733 b, but show still unexplained differences in the case of HD 209458 b. In contrast to general assumptions, we find that the gravitationally more tightly bound thermospheres of massive and compact planets, such as HAT-P-2 b are hydrodynamically stable. Compact planets dispose of the radiative energy input through hydrogen Lyα and free-free emission. Radiative cooling is also important in HD 189733 b, but it decreases toward smaller planets like GJ 436 b. Computing the planetary Lyα absorption and emission signals from the simulations, we find that the strong and cool winds of smaller planets mainly cause strong Lyα absorption but little emission. Compact and massive planets with hot, stable thermospheres cause small absorption signals but are strong Lyα emitters, possibly detectable with the current instrumentation. The absorption and emission signals provide a possible distinction between these two classes of thermospheres in hot gas planets. According to our results, WASP-80 and GJ 3470 are currently the most promising targets for observational follow-up aimed at detecting atmospheric Lyα absorption signals. Simulated atmospheres are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A75

Chemical fingerprints of hot Jupiter planet formation

NASA Astrophysics Data System (ADS)

Maldonado, J.; Villaver, E.; Eiroa, C.

2018-05-01

Context. The current paradigm to explain the presence of Jupiter-like planets with small orbital periods (P < 10 days; hot Jupiters), which involves their formation beyond the snow line following inward migration, has been challenged by recent works that explore the possibility of in situ formation. Aims: We aim to test whether stars harbouring hot Jupiters and stars with more distant gas-giant planets show any chemical peculiarity that could be related to different formation processes. Methods: Our methodology is based on the analysis of high-resolution échelle spectra. Stellar parameters and abundances of C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, and Zn for a sample of 88 planet hosts are derived. The sample is divided into stars hosting hot (a < 0.1 au) and cool (a > 0.1 au) Jupiter-like planets. The metallicity and abundance trends of the two sub-samples are compared and set in the context of current models of planet formation and migration. Results: Our results show that stars with hot Jupiters have higher metallicities than stars with cool distant gas-giant planets in the metallicity range +0.00/+0.20 dex. The data also shows a tendency of stars with cool Jupiters to show larger abundances of α elements. No abundance differences between stars with cool and hot Jupiters are found when considering iron peak, volatile elements or the C/O, and Mg/Si ratios. The corresponding p-values from the statistical tests comparing the cumulative distributions of cool and hot planet hosts are 0.20, <0.01, 0.81, and 0.16 for metallicity, α, iron-peak, and volatile elements, respectively. We confirm previous works suggesting that more distant planets show higher planetary masses as well as larger eccentricities. We note differences in age and spectral type between the hot and cool planet host samples that might affect the abundance comparison. Conclusions: The differences in the distribution of planetary mass, period, eccentricity, and stellar host metallicity suggest a different formation mechanism for hot and cool Jupiters. The slightly larger α abundances found in stars harbouring cool Jupiters might compensate their lower metallicities allowing the formation of gas-giant planets. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 072.C-0033(A), 072.C-0488(E), 074.B-0455(A), 075.C-0202(A), 077.C-0192(A), 077.D-0525(A), 078.C-0378(A), 078.C-0378(B), 080.A-9021(A), 082.C-0312(A) 082.C-0446(A), 083.A-9003(A), 083.A-9011(A), 083.A-9011(B), 083.A-9013(A), 083.C-0794(A), 084.A-9003(A), 084.A-9004(B), 085.A-9027(A), 085.C-0743(A), 087.A-9008(A), 088.C-0892(A), 089.C-0440(A), 089.C-0444(A), 089.C-0732(A), 090.C-0345(A), 092.A-9002(A), 192.C-0852(A), 60.A-9036(A), 60.A-9120(B), and 60.A-9700(A); and on data products from the SOPHIE archive.

Searching for Life: Early Earth, Mars and Beyond

NASA Technical Reports Server (NTRS)

DesMarais, David J.; Chang, Sherwood (Technical Monitor)

1996-01-01

We might be entering a golden age for exploring life throughout time and space. Rapid gene sequencing will better define our most distant ancestors. The earliest geologic evidence of life is now 3.8 billion years old. Organic matter and submicron-sized morphologies have been preserved in the martian crust for billions of years. Several new missions to Mars are planned, with a high priority on the search for life, past or present. The recent discovery of large extrasolar planets has heightened interest in spacecraft to detect small, earth-like planets. A recent workshop discussed strategies for life detection on such planets. There is much to anticipate in the near future.

Solar system plasma waves

NASA Technical Reports Server (NTRS)

Gurnett, Donald A.

1995-01-01

An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.

Occultations of Astrophysical Radio Sources as Probes of Planetary Environments: A Case Study of Jupiter and Possible Applications to Exoplanets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Withers, Paul; Vogt, Marissa F.

Properties of planetary atmospheres, ionospheres, and magnetospheres are difficult to measure from Earth. Radio occultations are a common method for measuring these properties, but they traditionally rely on radio transmissions from a spacecraft near the planet. Here, we explore whether occultations of radio emissions from a distant astrophysical radio source can be used to measure magnetic field strength, plasma density, and neutral density around planets. In a theoretical case study of Jupiter, we find that significant changes in polarization angle due to Faraday rotation occur for radio signals that pass within 10 Jupiter radii of the planet and that significantmore » changes in frequency and power occur from radio signals that pass through the neutral atmosphere. There are sufficient candidate radio sources, such as pulsars, active galactic nuclei, and masers, that occultations are likely to occur at least once per year. For pulsars, time delays in the arrival of their emitted pulses can be used to measure plasma density. Exoplanets, whose physical properties are very challenging to observe, may also occult distant astrophysical radio sources, such as their parent stars.« less

SIM Lite Detection of Habitable Planets in P-Type Binary-Planetary Systems

NASA Technical Reports Server (NTRS)

Pan, Xiaopei; Shao, Michael; Shaklan, Stuart; Goullioud, Renaud

2010-01-01

Close binary stars like spectroscopic binaries create a completely different environment than single stars for the evolution of a protoplanetary disk. Dynamical interactions between one star and protoplanets in such systems provide more challenges for theorists to model giant planet migration and formation of multiple planets. For habitable planets the majority of host stars are in binary star systems. So far only a small amount of Jupiter-size planets have been discovered in binary stars, whose minimum separations are 20 AU and the median value is about 1000 AU (because of difficulties in radial velocity measurements). The SIM Lite mission, a space-based astrometric observatory, has a unique capability to detect habitable planets in binary star systems. This work analyzed responses of the optical system to the field stop for companion stars and demonstrated that SIM Lite can observe exoplanets in visual binaries with small angular separations. In particular we investigated the issues for the search for terrestrial planets in P-type binary-planetary systems, where the planets move around both stars in a relatively distant orbit.

Pluto's Radius

NASA Astrophysics Data System (ADS)

Young, Eliot F.; Young, L. A.; Buie, M.

2007-10-01

The size of Pluto has been difficult to measure. Stellar occultations by Pluto have not yet probed altitudes lower than 1198 km, assuming the clear atmosphere model of Elliot, Person and Qu (2003). Differential refraction by Pluto's atmosphere attenuates the light from an occulted star to a level that is indistinguishable from the zero-level baseline long before Pluto's solid surface is a factor. Since Charon has no detectable atmosphere, its radius was well determined from a stellar occultation in 2005 (Gulbis et al. 2006, Sicardy et al. 2006). Combined with the mutual event photometry (Charon transited Pluto every 6.38 days between 1986 through 1992) - for which differential refraction is a negligible effect - the well-known radius of Charon translates into a more accurate radius for Pluto's solid surface. Our preliminary solid radius estimate for Pluto is 1161 km. We will discuss error bars and the correlations of this determination with Pluto albedo maps. We will also discuss the implications for Pluto's thermal profile, surface temperature and pressure, and constraints on the presence of a haze layer. This work is funded by NASA's Planetary Astronomy program. References Elliot, J.L., Person, M.J., & Qu, S. 2003, "Analysis of Stellar Occultation Data. II. Inversion, with Application to Pluto and Triton." AJ, 126, 1041. Gulbis, A.A.S. et al. 2006, "Charon's radius and atmospheric constraints from observations of a stellar occultation." Nature, 49, 48. Sicardy, B. et al. 2006, "Charon's size and an upper limit on its atmosphere from a stellar occultation." Nature, 49, 52.

MITEE: A Compact Ultralight Nuclear Thermal Propulsion Engine for Planetary Science Missions

NASA Astrophysics Data System (ADS)

Powell, J.; Maise, G.; Paniagua, J.

2001-01-01

A new approach for a near-term compact, ultralight nuclear thermal propulsion engine, termed MITEE (Miniature Reactor Engine) is described. MITEE enables a wide range of new and unique planetary science missions that are not possible with chemical rockets. With U-235 nuclear fuel and hydrogen propellant the baseline MITEE engine achieves a specific impulse of approximately 1000 seconds, a thrust of 28,000 newtons, and a total mass of only 140 kilograms, including reactor, controls, and turbo-pump. Using higher performance nuclear fuels like U-233, engine mass can be reduced to as little as 80 kg. Using MITEE, V additions of 20 km/s for missions to outer planets are possible compared to only 10 km/s for H2/O2 engines. The much greater V with MITEE enables much faster trips to the outer planets, e.g., two years to Jupiter, three years to Saturn, and five years to Pluto, without needing multiple planetary gravity assists. Moreover, MITEE can utilize in-situ resources to further extend mission V. One example of a very attractive, unique mission enabled by MITEE is the exploration of a possible subsurface ocean on Europa and the return of samples to Earth. Using MITEE, a spacecraft would land on Europa after a two-year trip from Earth orbit and deploy a small nuclear heated probe that would melt down through its ice sheet. The probe would then convert to a submersible and travel through the ocean collecting samples. After a few months, the probe would melt its way back up to the MITEE lander, which would have replenished its hydrogen propellant by melting and electrolyzing Europa surface ice. The spacecraft would then return to Earth. Total mission time is only five years, starting from departure from Earth orbit. Other unique missions include Neptune and Pluto orbiter, and even a Pluto sample return. MITEE uses the cermet Tungsten-UO2 fuel developed in the 1960's for the 710 reactor program. The W-UO2 fuel has demonstrated capability to operate in 3000 K hydrogen for many hours - a much longer period than the approximately one hour burn time for MITEE. Using this cermet fuel, and technology available from other nuclear propulsion programs, MITEE could be developed and ready for implementation in a relatively short time, i.e., approximately seven years. An overview description of the MITEE engine and its performance capabilities is provided.

Pluto' interaction with its space environment: Solar wind, energetic particles, and dust

NASA Astrophysics Data System (ADS)

Bagenal, F.; Horányi, M.; McComas, D. J.; McNutt, R. L.; Elliott, H. A.; Hill, M. E.; Brown, L. E.; Delamere, P. A.; Kollmann, P.; Krimigis, S. M.; Kusterer, M.; Lisse, C. M.; Mitchell, D. G.; Piquette, M.; Poppe, A. R.; Strobel, D. F.; Szalay, J. R.; Valek, P.; Vandegriff, J.; Weidner, S.; Zirnstein, E. J.; Stern, S. A.; Ennico, K.; Olkin, C. B.; Weaver, H. A.; Young, L. A.; Gladstone, G. R.; Grundy, W. M.; McKinnon, W. B.; Moore, J. M.; Spencer, J. R.; Andert, T.; Andrews, J.; Banks, M.; Bauer, B.; Bauman, J.; Barnouin, O. S.; Bedini, P.; Beisser, K.; Beyer, R. A.; Bhaskaran, S.; Binzel, R. P.; Birath, E.; Bird, M.; Bogan, D. J.; Bowman, A.; Bray, V. J.; Brozovic, M.; Bryan, C.; Buckley, M. R.; Buie, M. W.; Buratti, B. J.; Bushman, S. S.; Calloway, A.; Carcich, B.; Cheng, A. F.; Conard, S.; Conrad, C. A.; Cook, J. C.; Cruikshank, D. P.; Custodio, O. S.; Dalle Ore, C. M.; Deboy, C.; Dischner, Z. J. B.; Dumont, P.; Earle, A. M.; Ercol, J.; Ernst, C. M.; Finley, T.; Flanigan, S. H.; Fountain, G.; Freeze, M. J.; Greathouse, T.; Green, J. L.; Guo, Y.; Hahn, M.; Hamilton, D. P.; Hamilton, S. A.; Hanley, J.; Harch, A.; Hart, H. M.; Hersman, C. B.; Hill, A.; Hinson, D. P.; Holdridge, M. E.; Howard, A. D.; Howett, C. J. A.; Jackman, C.; Jacobson, R. A.; Jennings, D. E.; Kammer, J. A.; Kang, H. K.; Kaufmann, D. E.; Kusnierkiewicz, D.; Lauer, T. R.; Lee, J. E.; Lindstrom, K. L.; Linscott, I. R.; Lunsford, A. W.; Mallder, V. A.; Martin, N.; Mehoke, D.; Mehoke, T.; Melin, E. D.; Mutchler, M.; Nelson, D.; Nimmo, F.; Nunez, J. I.; Ocampo, A.; Owen, W. M.; Paetzold, M.; Page, B.; Parker, A. H.; Parker, J. W.; Pelletier, F.; Peterson, J.; Pinkine, N.; Porter, S. B.; Protopapa, S.; Redfern, J.; Reitsema, H. J.; Reuter, D. C.; Roberts, J. H.; Robbins, S. J.; Rogers, G.; Rose, D.; Runyon, K.; Retherford, K. D.; Ryschkewitsch, M. G.; Schenk, P.; Schindhelm, E.; Sepan, B.; Showalter, M. R.; Singer, K. N.; Soluri, M.; Stanbridge, D.; Steffl, A. J.; Stryk, T.; Summers, M. E.; Tapley, M.; Taylor, A.; Taylor, H.; Throop, H. B.; Tsang, C. C. C.; Tyler, G. L.; Umurhan, O. M.; Verbiscer, A. J.; Versteeg, M. H.; Vincent, M.; Webbert, R.; Weigle, G. E.; White, O. L.; Whittenburg, K.; Williams, B. G.; Williams, K.; Williams, S.; Woods, W. W.; Zangari, A. M.

2016-03-01

The New Horizons spacecraft carried three instruments that measured the space environment near Pluto as it flew by on 14 July 2015. The Solar Wind Around Pluto (SWAP) instrument revealed an interaction region confined sunward of Pluto to within about 6 Pluto radii. The region's surprisingly small size is consistent with a reduced atmospheric escape rate, as well as a particularly high solar wind flux. Observations from the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument suggest that ions are accelerated and/or deflected around Pluto. In the wake of the interaction region, PEPSSI observed suprathermal particle fluxes equal to about 1/10 of the flux in the interplanetary medium and increasing with distance downstream. The Venetia Burney Student Dust Counter, which measures grains with radii larger than 1.4 micrometers, detected one candidate impact in ±5 days around New Horizons' closest approach, indicating an upper limit of <4.6 kilometers-3 for the dust density in the Pluto system.

The far ultraviolet spectrum of Pluto and the discovery of its ionosphere

NASA Astrophysics Data System (ADS)

Steffl, A.; Stern, A.; Gladstone, R.; Parker, J. W.; Greathouse, T. K.; Retherford, K. D.; Young, L. A.; Schindhelm, E.; Kammer, J.; Strobel, D. F.; Summers, M. E.; Versteeg, M.; Olkin, C.; Weaver, H. A., Jr.; Hinson, D. P.; Linscott, I.

2016-12-01

During the New Horizons spacecraft's encounter with Pluto in July 2015, the Alice far ultraviolet spectrograph made numerous observations of Pluto and its atmosphere. We present here the far ultraviolet spectrum of Pluto. We observe faint emission (<0.01 Rayleighs/Ångstrom) from singly ionized nitrogen at 108.6 nm-the first detection of an ionosphere at Pluto. This N+ line is produced primarily by dissociative photoionization of molecular N2 by solar EUV photons (energy > 34.7 eV; wavelength < 36nm). Notably absent from Pluto's spectrum are emission lines from argon at 104.8 and 106.7 nm. We place upper limits on the amount of argon in Pluto's atmosphere above the tau=1 level (observed to be at 750km tangent altitude) that are significantly lower than previous models. We also identify and derive column densities for various hydrocarbon species such as C2H4 through their absorption of sunlight reflected from Pluto's surface.

Pluto's interaction with its space environment: Solar wind, energetic particles, and dust.

PubMed

Bagenal, F; Horányi, M; McComas, D J; McNutt, R L; Elliott, H A; Hill, M E; Brown, L E; Delamere, P A; Kollmann, P; Krimigis, S M; Kusterer, M; Lisse, C M; Mitchell, D G; Piquette, M; Poppe, A R; Strobel, D F; Szalay, J R; Valek, P; Vandegriff, J; Weidner, S; Zirnstein, E J; Stern, S A; Ennico, K; Olkin, C B; Weaver, H A; Young, L A

2016-03-18

The New Horizons spacecraft carried three instruments that measured the space environment near Pluto as it flew by on 14 July 2015. The Solar Wind Around Pluto (SWAP) instrument revealed an interaction region confined sunward of Pluto to within about 6 Pluto radii. The region's surprisingly small size is consistent with a reduced atmospheric escape rate, as well as a particularly high solar wind flux. Observations from the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument suggest that ions are accelerated and/or deflected around Pluto. In the wake of the interaction region, PEPSSI observed suprathermal particle fluxes equal to about 1/10 of the flux in the interplanetary medium and increasing with distance downstream. The Venetia Burney Student Dust Counter, which measures grains with radii larger than 1.4 micrometers, detected one candidate impact in ±5 days around New Horizons' closest approach, indicating an upper limit of <4.6 kilometers(-3) for the dust density in the Pluto system. Copyright © 2016, American Association for the Advancement of Science.

Probing the Impact of Stellar Duplicity on Planet Occurrence with Spectroscopic and Imaging Observations

NASA Astrophysics Data System (ADS)

Eggenberger, Anne; Udry, Stéphane

Over the past 14 years, Doppler spectroscopy has been very successful in detecting and characterizing extrasolar planets, providing us with a wealth of information on these distant worlds (e.g., Marcy et al. 2005a; Udry and Santos 2007b; Udry et al. 2007a). One important and considerably unexpected fact these new data have taught us is that diversity is the rule in the planetary world. Diversity is found not only in the characteristics and orbital properties of the ˜ 340 planets detected thus far,1 but also in the types of environments in which they reside and are able to form. This observation has prompted a serious revision of the theories of planet formation (e.g., Lissauer and Stevenson 2007; Durisen et al. 2007; Nagasawa et al. 2007), leading to the idea that planet formation may be a richer and more robust process than originally thought.

Alpha Centauri's siren call has frustrated planet hunters

NASA Astrophysics Data System (ADS)

Clery, Daniel

2018-04-01

Alpha Centauri, a three-star system just 4 light-years away that is the sun's nearest neighbor, ought to be a great place to look for Earth-like planets. But last week, at a meeting of the European Astronomical Society here, astronomers lamented that the system has so far thwarted discovery efforts—and announced new schemes to probe it. The two sunlike stars, Alpha Centauri A and B, orbit each other closely while Proxima Centauri, a tempestuous red dwarf, hangs onto the system tenuously in a much more distant orbit. In 2016, astronomers discovered an Earth-mass planet around Proxima Centauri, but few think the planet, blasted by radiation and fierce stellar winds, is habitable. Astrobiologists believe the other two stars are more likely to host temperate, Earth-like worlds.

Implications of the observed Pluto-Charon density contrast

NASA Astrophysics Data System (ADS)

Bierson, C. J.; Nimmo, F.; McKinnon, W. B.

2018-07-01

Observations by the New Horizons spacecraft have determined that Pluto has a larger bulk density than Charon by 153 ± 44 kg m-3 (2σ uncertainty). We use a thermal model of Pluto and Charon to determine if this density contrast could be due to porosity variations alone, with Pluto and Charon having the same bulk composition. We find that Charon can preserve a larger porous ice layer than Pluto due to its lower gravity and lower heat flux but that the density contrast can only be explained if the initial ice porosity is ≳ 30%, extends to ≳100 km depth and Pluto retains a subsurface ocean today. We also find that other processes such as a modern ocean on Pluto, self-compression, water-rock interactions, and volatile (e.g., CO) loss cannot, even in combination, explain this difference in density. Although an initially high porosity cannot be completely ruled out, we conclude that it is more probable that Pluto and Charon have different bulk compositions. This difference could arise either from forming Charon via a giant impact, or via preferential loss of H2O on Pluto due to heating during rapid accretion.

Planetary Taxonomy: Label Round Bodies "Worlds"

NASA Astrophysics Data System (ADS)

Margot, Jean-Luc; Levison, H. F.

2009-05-01

The classification of planetary bodies is as important to Astronomy as taxonomy is to other sciences. The etymological, historical, and IAU definitions of planet rely on a dynamical criterion, but some authors prefer a geophysical criterion based on "roundness". Although the former criterion is superior when it comes to classifying newly discovered objects, the conflict need not exist if we agree to identify the subset of "round" planetary objects as "worlds". This addition to the taxonomy would conveniently recognize that "round" objects such as Earth, Europa, Titan, Triton, and Pluto share some common planetary-type processes regardless of their distance from the host star. Some of these worlds are planets, others are not. Defining how round is round and handling the inevitable transition objects are non-trivial tasks. Because images at sufficient resolution are not available for the overwhelming majority of newly discovered objects, the degree of roundness is not a directly observable property and is inherently problematic as a basis for classification. We can tolerate some uncertainty in establishing the "world" status of a newly discovered object, and still establish its planet or satellite status with existing dynamical criteria. Because orbital parameters are directly observable, and because mass can often be measured either from orbital perturbations or from the presence of companions, the dynamics provide a robust and practical planet classification scheme. It may also be possible to determine which bodies are dynamically dominant from observations of the population magnitude/size distribution.

Predictable Patterns in Planetary Transit Timing Variations and Transit Duration Variations Due to Exomoons

NASA Technical Reports Server (NTRS)

Heller, Rene; Hippke, Michael; Placek, Ben; Angerhausen, Daniel; Agol, Eric

2016-01-01

We present new ways to identify single and multiple moons around extrasolar planets using planetary transit timing variations (TTVs) and transit duration variations (TDVs). For planets with one moon, measurements from successive transits exhibit a hitherto undescribed pattern in the TTV-TDV diagram, originating from the stroboscopic sampling of the planet's orbit around the planet-moon barycenter. This pattern is fully determined and analytically predictable after three consecutive transits. The more measurements become available, the more the TTV-TDV diagram approaches an ellipse. For planets with multiple moons in orbital mean motion resonance (MMR), like the Galilean moon system, the pattern is much more complex and addressed numerically in this report. Exomoons in MMR can also form closed, predictable TTV-TDV figures, as long as the drift of the moons' pericenters is suciently slow.We find that MMR exomoons produce loops in the TTV-TDV diagram and that the number of these loops is equal to the order of the MMR, or the largest integer in the MMR ratio.We use a Bayesian model and Monte Carlo simulations to test the discoverability of exomoons using TTV-TDV diagrams with current and near-future technology. In a blind test, two of us (BP, DA) successfully retrieved a large moon from simulated TTV-TDV by co-authors MH and RH, which resembled data from a known Kepler planet candidate. Single exomoons with a 10 percent moon-to-planet mass ratio, like to Pluto-Charon binary, can be detectable in the archival data of the Kepler primary mission. Multi-exomoon systems, however, require either larger telescopes or brighter target stars. Complementary detection methods invoking a moon's own photometric transit or its orbital sampling effect can be used for validation or falsification. A combination of TESS, CHEOPS, and PLATO data would offer a compelling opportunity for an exomoon discovery around a bright star.

The fate of scattered planets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bromley, Benjamin C.; Kenyon, Scott J., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu

2014-12-01

As gas giant planets evolve, they may scatter other planets far from their original orbits to produce hot Jupiters or rogue planets that are not gravitationally bound to any star. Here, we consider planets cast out to large orbital distances on eccentric, bound orbits through a gaseous disk. With simple numerical models, we show that super-Earths can interact with the gas through dynamical friction to settle in the remote outer regions of a planetary system. Outcomes depend on planet mass, the initial scattered orbit, and the evolution of the time-dependent disk. Efficient orbital damping by dynamical friction requires planets atmore » least as massive as the Earth. More massive, longer-lived disks damp eccentricities more efficiently than less massive, short-lived ones. Transition disks with an expanding inner cavity can circularize orbits at larger distances than disks that experience a global (homologous) decay in surface density. Thus, orbits of remote planets may reveal the evolutionary history of their primordial gas disks. A remote planet with an orbital distance ∼100 AU from the Sun is plausible and might explain correlations in the orbital parameters of several distant trans-Neptunian objects.« less

Flying Past Pluto Animation

NASA Image and Video Library

2015-08-28

This dramatic view of the Pluto system is as NASA's New Horizons spacecraft saw it in July 2015. The animation, made with real images taken by New Horizons, begins with Pluto flying in for its close-up on July 14; we then pass behind Pluto and see the atmosphere glow in sunlight before the sun passes behind Pluto's largest moon, Charon. The movie ends with New Horizons' departure, looking back on each body as thin crescents. http://photojournal.jpl.nasa.gov/catalog/PIA19873

Icy Satellites of the Planets, and the Work of V.I. Moroz

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.

2006-01-01

The satellites of the giant planets are highly varied in size and density, indicating a wide range of compositions. The principal components of these satellites are ices of many different compositions (with H2O the most abundant) and varying amounts of silicate rocky material. Many different ices have been found by spectroscopic techniques both from Earth-based observatories and from planetary spacecraft. Three of the Galilean satellites of Jupiter exhibit H2O ice on their surfaces, while small amounts of CO2 are present on Ganymede and Callisto. The volcanic satellite Io has abundant SO2 ice and frost deposits. Saturn s satellites have surfaces dominated by H2O ice, but CO2 is also present on most of them, and in the cases of the low-albedo satellites Iapetus and Phoebe, there is evidence of complex hydrocarbons mixed with the surface materials. The large Uranian satellites also have H2O-dominated surfaces, but CO2 has also been discovered on two of them. Neptune s largest satellite, Triton, show spectroscopic evidence for six different ices, including N2, CH4, CO, CO2, H2O, and C2H6. The latter ice is a photochemical product from the action of sunlight on Triton's atmosphere. Pluto is similar to Triton, although CO2 has not been found. Pluto s large satellite, Charon, shows evidence for an ammonia hydrate on part of its surface. V. I. Moroz was a pioneer in the application of near-infrared detectors to astronomical sources. Using a prism spectrometer he measured the spectra of the Galilean satellites of Jupiter, and in 1966 he published the first near-infrared spectra, noting the appearance of H2O ice as a major component of Europa and Ganymede. This discovery, and the techniques of Moroz measurements help set the stage for the broad extension of the study of planetary, satellite, and asteroid surfaces through reflectance spectroscopy in the near-infrared.

Pluto-Charon solar wind interaction dynamics

NASA Astrophysics Data System (ADS)

Hale, J. P. M.; Paty, C. S.

2017-05-01

This work studies Charon's effects on the Pluto-solar wind interaction using a multifluid MHD model which simulates the interactions of Pluto and Charon with the solar wind as well as with each other. Specifically, it investigates the ionospheric dynamics of a two body system in which either one or both bodies possess an ionosphere. Configurations in which Charon is directly upstream and directly downstream of Pluto are considered. Depending on ionospheric and solar wind conditions, Charon could periodically pass into the solar wind flow upstream of Pluto. The results of this study demonstrate that in these circumstances Charon modifies the upstream flow, both in the case in which Charon possesses an ionosphere, and in the case in which Charon is without an ionosphere. This modification amounts to a change in the gross structure of the interaction region when Charon possesses an ionosphere but is more localized when Charon lacks an ionosphere. Furthermore, evidence is shown that supports Charon acting to partially shield Pluto from the solar wind when it is upstream of Pluto, resulting in a decrease in ionospheric loss by Pluto.

Pluto Haze

NASA Image and Video Library

2015-09-10

Two different versions of an image of Pluto's haze layers, taken by New Horizons as it looked back at Pluto's dark side nearly 16 hours after close approach, from a distance of 480,000 miles (770,000 kilometers), at a phase angle of 166 degrees. Pluto's north is at the top, and the sun illuminates Pluto from the upper right. These images are much higher quality than the digitally compressed images of Pluto's haze downlinked and released shortly after the July 14 encounter, and allow many new details to be seen. The left version has had only minor processing, while the right version has been specially processed to reveal a large number of discrete haze layers in the atmosphere. In the left version, faint surface details on the narrow sunlit crescent are seen through the haze in the upper right of Pluto's disk, and subtle parallel streaks in the haze may be crepuscular rays- shadows cast on the haze by topography such as mountain ranges on Pluto, similar to the rays sometimes seen in the sky after the sun sets behind mountains on Earth. http://photojournal.jpl.nasa.gov/catalog/PIA19880

Which Type of Planets do We Expect to Observe in the Habitable Zone?

PubMed

Adibekyan, Vardan; Figueira, Pedro; Santos, Nuno C

2016-11-01

We used a sample of super-Earth-like planets detected by the Doppler spectroscopy and transit techniques to explore the dependence of orbital parameters of the planets on the metallicity of their host stars. We confirm the previous results (although still based on small samples of planets) that super-Earths orbiting around metal-rich stars are not observed to be as distant from their host stars as we observe their metal-poor counterparts to be. The orbits of these super-Earths with metal-rich hosts usually do not reach into the Habitable Zone (HZ), keeping them very hot and inhabitable. We found that most of the known planets in the HZ are orbiting their GK-type hosts which are metal-poor. The metal-poor nature of planets in the HZ suggests a high Mg abundance relative to Si and high Si abundance relative to Fe. These results lead us to speculate that HZ planets might be more frequent in the ancient Galaxy and had compositions different from that of our Earth.

Survival of planets around shrinking stellar binaries

PubMed Central

Muñoz, Diego J.; Lai, Dong

2015-01-01

The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov–Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like. PMID:26159412

Survival of planets around shrinking stellar binaries.

PubMed

Muñoz, Diego J; Lai, Dong

2015-07-28

The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov-Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like.

2012 DR30, The Most Distant Solar System Object

NASA Astrophysics Data System (ADS)

Kiss, Csaba; Szabó, G.; Pál, A.; Kiss, L.; Sárneczky, K.; Müller, T.; Vilenius, E.; Santos-Sanz, P.; Lellouch, E.; Conn, B.; Ortiz, J.; Duffard, R.; Morales, N.; Horner, J.; Bannister, M.; Stansberry, J.

2012-10-01

2012 DR30, the most distant TNO in the Solar System (a=1103 AU) has recently been observed with the Herschel Space Observatory. Radiometric model results using the far-infrared fluxes and visual range data show a dark and cratered surface (p_V = 6%) and provide a diameter of 200km. If considered as a Centaur, this is the fifth largest object known in this dynamical class. Recent visual range measurements indicate the presence of methane ice on the surface, a feature that has been seen previously for objects with diameters of >=1000km only (like Eris, Makemake and Pluto). The presence of methane ice can be explained assuming that the object spent most of its lifetime in a very cold environment and has been recently placed to its present orbit. This scenario is in agreement with the results of a dynamical study of the object's orbit, also suggesting an Oort-cloud origin. This research has been supported by the following grants: (1) The PECS program of the European Space Agency (ESA) and the Hungarian Space Office, PECS-98073; (2) C.K. and A.P. acknowledges the support of the Bolyai Research Fellowship of the Hungarian Academy of Sciences.

The Cosmochemistry of Pluto: A Primordial Origin of Volatiles?

NASA Astrophysics Data System (ADS)

Glein, C. R.; Waite, J. H., Jr.

2017-12-01

Pluto is a wonderland of volatiles. Nitrogen, methane, and carbon monoxide are the principal volatiles that maintain its tenuous atmosphere, and they have also created a mesmerizing landscape of icy geological features, including Pluto's iconic "heart". Recent data, particularly those returned by the New Horizons mission [1-3], allow us to begin testing hypotheses for the cosmochemical origins of these world-shaping species on Pluto. Here, we investigate if Pluto's volatiles could have been accreted in its building blocks. We take both bottom-up and top-down approaches in testing this hypothesis in terms of mass balance. We estimate Pluto's primordial inventory of volatiles by scaling a range of cometary abundances up to the ice mass fraction of Pluto. We also make estimates of the present and lost inventories of volatiles based on surface observations and interpretations, as well as different scenarios of atmospheric photochemistry and escape. We find that, if primordial Pluto resembled a giant comet with respect to volatile abundances, then the initial volatile inventory would have been sufficient to account for the estimated present and lost inventories. This consistency supports a primordial origin for Pluto's volatiles. However, the observed ratio of CO/N2 in Pluto's atmosphere [4] is several orders of magnitude lower than the nominal cometary value. We are currently using phase equilibrium and rate models to explore if volatile layering in Sputnik Planitia, or the destruction of CO in a past or present subsurface ocean of liquid water could explain the apparent depletion of CO on Pluto. References: [1] Moore et al. (2016) Science 351, 1284. [2] Grundy et al. (2016) Science 351, aad9189. [3] Gladstone et al. (2016) Science 351, aad8866. [4] Lellouch et al. (2017) Icarus 286, 289.

Secrets Revealed from Pluto Twilight Zone

NASA Image and Video Library

2016-06-02

NASA's New Horizons spacecraft took this stunning image of Pluto only a few minutes after closest approach on July 14, 2015. The image was obtained at a high phase angle -- that is, with the sun on the other side of Pluto, as viewed by New Horizons. Seen here, sunlight filters through and illuminates Pluto's complex atmospheric haze layers. The southern portions of the nitrogen ice plains informally named Sputnik Planum, as well as mountains of the informally named Norgay Montes, can also be seen across Pluto's crescent at the top of the image. Looking back at Pluto with images like this gives New Horizons scientists information about Pluto's hazes and surface properties that they can't get from images taken on approach. The image was obtained by New Horizons' Ralph/Multispectral Visual Imaging Camera (MVIC) approximately 13,400 miles (21,550 kilometers) from Pluto, about 19 minutes after New Horizons' closest approach. The image has a resolution of 1,400 feet (430 meters) per pixel. Pluto's diameter is 1,475 miles (2,374 kilometers). The inset at top right in the annotated version shows a detail of Pluto's crescent, including an intriguing bright wisp (near the center) measuring tens of miles across that may be a discreet, low-lying cloud in Pluto's atmosphere; if so, it would be the only one yet identified in New Horizons imagery. This cloud -- if that's what it is -- is visible for the same reason the haze layers are so bright: illumination from the sunlight grazing Pluto's surface at a low angle. Atmospheric models suggest that methane clouds can occasionally form in Pluto's atmosphere. The scene in this inset is 140 miles (230 kilometers) across. The inset at bottom right shows more detail on the night side of Pluto. This terrain can be seen because it is illuminated from behind by hazes that silhouette the of the annotated version limb. The topography here appears quite rugged, and broad valleys and sharp peaks with relief totaling 3 miles (5 kilometers) are apparent. This image, made from closer range, is much better than the lower-resolution images of this same terrain taken several days before closest approach. These silhouetted terrains therefore act as a useful "anchor point," giving New Horizons scientists a rare, detailed glimpse at the lay of the land in this mysterious part of Pluto seen at high resolution only in twilight. The scene in this inset is 460 miles (750 kilometers) wide. http://photojournal.jpl.nasa.gov/catalog/PIA20727

Comet and Asteroid Hazard to the Terrestrial Planets

NASA Technical Reports Server (NTRS)

Ipatov, S. I.; Mather, J. C.; Oegerle, William (Technical Monitor)

2002-01-01

We made computer simulations of orbital evolution for intervals of at least 5-10 Myr of N=2000 Jupiter-crossing objects (JCOs) with initial orbits close to those of real comets with period P less than 10 yr, 500 objects with orbits close to that of Comet 10P, and the asteroids initially located at the 3:1 and 5:2 resonances with Jupiter at initial eccentricity e(sub 0)=0.15 and initial inclination i(sub 0)=10(sup 0). The gravitational influence of all planets, except for Mercury and Pluto, was taken into account (without dissipative factors). We calculated the probabilities of collisions of bodies with the terrestrial planets, using orbital elements obtained with a step equal to 500 yr, and then summarized the results for all bodies, obtaining, the total probability Psigma of collisions with a planet and the total time interval Tsigma during which perihelion distance q of bodies was less than a semimajor axis of the planet. The values of p(sub r) =10(exp 6)Psigma/N and T(sub r)=T/1000 yr (where T=Tsigma/N) are presented in a table together with the ratio r of the total time interval when orbits were of Apollo type (at a greater than 1 AU, q less than 1.017 AU, e less than 0.999) to that of Amor type (1.017 less than q less than 1.33 AU), r(sub 2) is the same as r but for Apollo objects with e less than 0.9. For asteroids we present only results obtained by direct integration, as a symplectic method can give large errors for these resonances.

The Sensitivity to Trans-Neptunian Dwarf Planets of the Siding Spring Survey

NASA Astrophysics Data System (ADS)

Bannister, Michele; Brown, M. E.; Schmidt, B. P.; Francis, P.; McNaught, R.; Garrad, G.; Larson, S.; Beshore, E.

2012-10-01

The last decade has seen considerable effort in assessing the populations of icy worlds in the outer Solar System, with major surveys in the Northern and more recently, in the Southern Hemisphere skies. Our archival search of more than ten thousand square degrees of sky south of the ecliptic observed over five years is a bright-object survey, sensitive to dwarf-planet sized trans-Neptunian objects. Our innovative survey analyses observations of the Siding Spring Survey, an ongoing survey for near-Earth asteroids at the 0.5 m Uppsala telescope at Siding Spring Observatory. This survey observed each of 2300 4.55 square degree fields on between 30 and 90 of the nights from early 2004 to late 2009, creating a dataset with dense temporal coverage, which we reprocessed for TNOs with a dedicated pipeline. We assess our survey's sensitivity to trans-Neptunian objects by simulating the observation of the synthetic outer Solar System populations of Grav et al. (2011): Centaurs, Kuiper belt and scattered disk. As our fields span approx. -15 to -70 declination, avoiding the galactic plane by 10 degrees either side, we are particularly sensitive to dwarf planets in high-inclination orbits. Partly due to this coverage far from the ecliptic, all known dwarf planets, including Pluto, do fall outside our survey coverage in its temporal span. We apply the widest plausible range of absolute magnitudes to each observable synthetic object, measuring each subsequent apparent magnitude against the magnitude depth of the survey observations. We evaluate our survey's null detection of new dwarf planets in light of our detection efficiencies as a function of trans-Neptunian orbital parameter space. MTB appreciates the funding support of the Joan Duffield Postgraduate Scholarship, an Australian Postgraduate Award, and the Astronomical Society of Australia.

Clues From Pluto's Ions

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-05-01

Nearly a year ago, in July 2015, the New Horizons spacecraft passed by the Pluto system. The wealth of data amassed from that flyby is still being analyzed including data from the Solar Wind Around Pluto (SWAP) instrument. Recent examination of this data has revealedinteresting new information about Plutos atmosphere and how the solar wind interacts with it.A Heavy Ion TailThe solar wind is a constant stream of charged particles released by the Sun at speeds of around 400 km/s (thats 1 million mph!). This wind travels out to the far reaches of the solar system, interacting with the bodies it encounters along the way.By modeling the SWAP detections, the authors determine the directions of the IMF that could produce the heavy ions detected. Red pixels represent IMF directions permitted. No possible IMF could reproduce the detections if the ions are nitrogen (bottom panels), and only retrograde IMF directions can produce the detections if the ions are methane. [Adapted from Zirnstein et al. 2016]New Horizons data has revealed that Plutos atmosphere leaks neutral nitrogen, methane, and carbon monoxide molecules that sometimes escape its weak gravitational pull. These molecules become ionized and are subsequently picked up by the passing solar wind, forming a tail of heavy ions behind Pluto. The details of the geometry and composition of this tail, however, had not yet been determined.Escaping MethaneIn a recent study led by Eric Zirnstein (Southwest Research Institute), the latest analysis of data from the SWAP instrument on board New Horizons is reported. The team used SWAPs ion detections from just after New Horizons closest approach to Pluto to better understand how the heavy ions around Pluto behave, and how the solar wind interacts with Plutos atmosphere.In the process of analyzing the SWAP data, Zirnstein and collaborators first establish what the majority of the heavy ions picked up by the solar wind are. Models of the SWAP detections indicate they are unlikely to be nitrogen ions, despite nitrogen being the most abundant molecule in Plutos atmosphere. Instead, the detections are likely of methane ions possibly present because methane molecules are lighter, allowing them to more efficiently escape Plutos atmosphere.Reconstructed origins of heavy ions detected by SWAP shortly after New Horizons closest approach to Pluto. Color represents the energy at the time of detection. [Adapted from Zirnstein et al. 2016]Magnetic DirectionNew Horizons does not have a magnetometer on board, which prevented it from making direct measurements of the interplanetary magnetic field (IMF; the solar magnetic field extended throughout the solar system) during the Pluto encounter. In spite of this, Zirnstein and collaborators are able to determine the IMF direction using some clever calculations about SWAPs field of view and the energies of heavy ions it detected.They demonstrate that the IMF was likely oriented roughly parallel to the ecliptic plane, and in the opposite direction of Plutos orbital motion, during New Horizons Pluto encounter. This would cause the solar wind to deflect southward around Pluto, resulting in a north-south asymmetry in the heavy ion tail behind Pluto.The new knowledge gained from SWAP about the geometry and the composition of Plutos extended atmosphere will help us to interpret further data from New Horizons. Ultimately, this provides us with a better understanding both of Plutos atmosphere and how the solar wind interacts with bodies in our solar system.CitationE. J. Zirnstein et al 2016 ApJ 823 L30. doi:10.3847/2041-8205/823/2/L30

Speckle interferometry applied to asteroids and other solar system objects

NASA Technical Reports Server (NTRS)

Drummond, J. D.; Hege, E. K.

1986-01-01

Speckle interferometry is a high angular resolution technique that allows study of resolved asteroids. By following the changing size, shape, and orientation of minor planets, and with a few general assumptions (e.g., geometric scattering, triaxial ellipsoid figures, no albedo features), it is possible to directly measure an asteroid's true dimensions and the direction of its spin axis in one or two nights. A particular subset of triaxial ellipsoid figures are equilibrium shapes, and would imply that some asteroids are thoroughly fractured. Such shapes if they exist among the asteroids would allow a determination of bulk density since there is a unique relation among spin period, size, shape, and density. The discovery of even a single rubble pile, (just as the finding of even one binary asteroid by speckle interferometric techniques) would drastically alter the notion of asteroids as small solid planets. The Pluto/Charon system was studied to aid in improving the orbital elements necessary to predict the eclipse/occultation season currently in progress. Four asteroids were reduced to their size, shape, and pole direction: 433 Eros, 532 Herculina, 511 Davida, and 2 Pallas.

How to Find a Planetary Hot Spot

NASA Image and Video Library

2010-10-19

This graph of data from NASA Spitzer Space Telescope shows how astronomers located a hot spot on a distant gas planet named upsilon Andromedae b. Termed an exoplanet, it orbits a star beyond our sun, and whips around very closely to its star.

12 years of Pluto surface's evolution investigated with radiative transfer modeling

NASA Astrophysics Data System (ADS)

Philippe, Sylvain; Schmitt, Bernard; Grundy, William; Protopapa, Silvia; Olkin, Cathy

2015-11-01

The evolution of Pluto’s surface through time, due to surface - atmosphere interactions, remains unknown. New Horizons will provide very high spatial resolution data of its surface state but only as a snapshot. Furthermore, this evolution during the last decades is supposed to be fast due to the recent passage of Pluto through its perihelion (1989). Ground based survey data over a long period of time are thus crucial to understand the long-term evolution of the dwarf planet surface.IRTF/SpeX reflectance spectra of Pluto have been acquired during 13 years (2001-2013) between 0.8-2.4 μm (Grundy et al., 2013; Grundy et al., 2014). This set of data present the opportunity to monitor possible changes of the surface in terms of geographical distribution and segregation between different chemical species that are known to be present at the surface in an icy state (N2, CH4 and CO, Owen et al., 1993, Douté et al., 1999). These variations are recorded through changes in the infrared absorption bands of the different ices. A study based on band criteria variation (Grundy et al., 2013) showed that CH4 absorption bands are increasing through time, whereas N2 and CO absorptions bands are decreasing (Grundy et al. 2014). However, quantitative interpretation of these data needs further investigation and detailed radiative transfer modeling.We used the bidirectional reflectance model of Douté & Schmitt (1998) to fit the IRTF/SpeX spectral data. This model takes into account a possible stratification of chemical species, a phenomenon that is likely to occur on Pluto where CH4 is supposed to accumulate on a sublimating molecular mixture of N2-CH4-CO (Douté et al., 1999). Different modelings take into account pure CH4 ice, a molecular mixture of N2-CH4-CO, tholins and water ice. We modeled the grand average spectra and then allowed the parameters to vary around the average values to model individual spectra and get quantitative variations of the different species.Preliminary results of these modelings will be presented in terms of longitudinal and temporal variations. This study could provide a useful precursor for the analysis of the spatially resolved New Horizon hyper spectral data acquired by the RALPH/Leisa instrument.

Methane in Pluto's Atmosphere

NASA Astrophysics Data System (ADS)

Roe, Henry G.

2006-09-01

The abundance of methane in Pluto's atmosphere has not been remeasured since its initial detection in 1992 by Young et al. (1997). As Pluto recedes from the Sun its atmosphere should eventually collapse and freeze out on the surface, but recent occultation observations (Elliot et al. 2003) show an expansion of the atmosphere rather than contraction. New measurements of Pluto's atmospheric methane abundance are warranted. We obtained high resolution (R=25000) near-infrared spectra of Pluto in July 2006 with NIRSPEC at the W.M. Keck II telescope and will report our initial analysis and results.

Global Mosaics of Pluto and Charon

NASA Image and Video Library

2017-07-14

Global mosaics of Pluto and Charon projected at 300 meters (985 feet) per pixel that have been assembled from most of the highest resolution images obtained by the Long-Range Reconnaissance Imager (LORRI) and the Multispectral Visible Imaging Camera (MVIC) onboard New Horizons. Transparent, colorized stereo topography data generated for the encounter hemispheres of Pluto and Charon have been overlain on the mosaics. Terrain south of about 30°S on Pluto and Charon was in darkness leading up to and during the flyby, so is shown in black. "S" and "T" respectively indicate Sputnik Planitia and Tartarus Dorsa on Pluto, and "C" indicates Caleuche Chasma on Charon. All feature names on Pluto and Charon are informal. https://photojournal.jpl.nasa.gov/catalog/PIA21862

Improved orbital and physical parameters for the Pluto-Charon system

NASA Astrophysics Data System (ADS)

Tholen, D. J.; Buie, M. W.; Binzel, R. P.; Frueh, M. L.

1987-07-01

Analysis of the observations of several Pluto-Charon occultation and transit events in 1985 and 1986 has provided a more detailed knowledge of the system. The sum of the radii of Pluto and Charon is 1786±19 kilometers, but the individual radii are somewhat more poorly determined; Pluto is 1145±46 kilometers in radius and Charon is 642±34 kilometers in radius. The mean density of the system is 1.84±0.19 grams per cubic centimeter implying that more than half of the mass is due to rock. Charon appears to have hemispheres of two different colors, the Pluto-facing side being neutral in color and the opposite hemisphere being a reddish color similar to Pluto.

On the Detectability of Planet X with LSST

NASA Astrophysics Data System (ADS)

Trilling, David E.; Bellm, Eric C.; Malhotra, Renu

2018-06-01

Two planetary mass objects in the far outer solar system—collectively referred to here as Planet X— have recently been hypothesized to explain the orbital distribution of distant Kuiper Belt Objects. Neither planet is thought to be exceptionally faint, but the sky locations of these putative planets are poorly constrained. Therefore, a wide area survey is needed to detect these possible planets. The Large Synoptic Survey Telescope (LSST) will carry out an unbiased, large area (around 18000 deg2), deep (limiting magnitude of individual frames of 24.5) survey (the “wide-fast-deep (WFD)” survey) of the southern sky beginning in 2022, and it will therefore be an important tool in searching for these hypothesized planets. Here, we explore the effectiveness of LSST as a search platform for these possible planets. Assuming the current baseline cadence (which includes the WFD survey plus additional coverage), we estimate that LSST will confidently detect or rule out the existence of Planet X in 61% of the entire sky. At orbital distances up to ∼75 au, Planet X could simply be found in the normal nightly moving object processing; at larger distances, it will require custom data processing. We also discuss the implications of a nondetection of Planet X in LSST data.

Pervasive orbital eccentricities dictate the habitability of extrasolar earths.

PubMed

Kita, Ryosuke; Rasio, Frederic; Takeda, Genya

2010-09-01

The long-term habitability of Earth-like planets requires low orbital eccentricities. A secular perturbation from a distant stellar companion is a very important mechanism in exciting planetary eccentricities, as many of the extrasolar planetary systems are associated with stellar companions. Although the orbital evolution of an Earth-like planet in a stellar binary system is well understood, the effect of a binary perturbation on a more realistic system containing additional gas-giant planets has been very little studied. Here, we provide analytic criteria confirmed by a large ensemble of numerical integrations that identify the initial orbital parameters leading to eccentric orbits. We show that an extrasolar earth is likely to experience a broad range of orbital evolution dictated by the location of a gas-giant planet, which necessitates more focused studies on the effect of eccentricity on the potential for life.

Triton's Summer Sky of Methane and Carbon Monoxide

NASA Astrophysics Data System (ADS)

2010-04-01

According to the first ever infrared analysis of the atmosphere of Neptune's moon Triton, summer is in full swing in its southern hemisphere. The European observing team used ESO's Very Large Telescope and discovered carbon monoxide and made the first ground-based detection of methane in Triton's thin atmosphere. These observations revealed that the thin atmosphere varies seasonally, thickening when warmed. "We have found real evidence that the Sun still makes its presence felt on Triton, even from so far away. This icy moon actually has seasons just as we do on Earth, but they change far more slowly," says Emmanuel Lellouch, the lead author of the paper reporting these results in Astronomy & Astrophysics. On Triton, where the average surface temperature is about minus 235 degrees Celsius, it is currently summer in the southern hemisphere and winter in the northern. As Triton's southern hemisphere warms up, a thin layer of frozen nitrogen, methane, and carbon monoxide on Triton's surface sublimates into gas, thickening the icy atmosphere as the season progresses during Neptune's 165-year orbit around the Sun. A season on Triton lasts a little over 40 years, and Triton passed the southern summer solstice in 2000. Based on the amount of gas measured, Lellouch and his colleagues estimate that Triton's atmospheric pressure may have risen by a factor of four compared to the measurements made by Voyager 2 in 1989, when it was still spring on the giant moon. The atmospheric pressure on Triton is now between 40 and 65 microbars - 20 000 times less than on Earth. Carbon monoxide was known to be present as ice on the surface, but Lellouch and his team discovered that Triton's upper surface layer is enriched with carbon monoxide ice by about a factor of ten compared to the deeper layers, and that it is this upper "film" that feeds the atmosphere. While the majority of Triton's atmosphere is nitrogen (much like on Earth), the methane in the atmosphere, first detected by Voyager 2, and only now confirmed in this study from Earth, plays an important role as well. "Climate and atmospheric models of Triton have to be revisited now, now that we have found carbon monoxide and re-measured the methane," says co-author Catherine de Bergh. Of Neptune's 13 moons, Triton is by far the largest, and, at 2700 kilometres in diameter (or three quarters the Earth's Moon), is the seventh largest moon in the whole Solar System. Since its discovery in 1846, Triton has fascinated astronomers thanks to its geologic activity, the many different types of surface ices, such as frozen nitrogen as well as water and dry ice (frozen carbon dioxide), and its unique retrograde motion [1]. Observing the atmosphere of Triton, which is roughly 30 times further from the Sun than Earth, is not easy. In the 1980s, astronomers theorised that the atmosphere on Neptune's moon might be as thick as that of Mars (7 millibars). It wasn't until Voyager 2 passed the planet in 1989 that the atmosphere of nitrogen and methane, at an actual pressure of 14 microbars, 70 000 times less dense than the atmosphere on Earth, was measured. Since then, ground-based observations have been limited. Observations of stellar occultations (a phenomenon that occurs when a Solar System body passes in front of a star and blocks its light) indicated that Triton's surface pressure was increasing in the 1990's. It took the development of the Cryogenic High-Resolution Infrared Echelle Spectrograph (CRIRES) at the Very Large Telescope (VLT) to provide the team the chance to perform a far more detailed study of Triton's atmosphere. "We needed the sensitivity and capability of CRIRES to take very detailed spectra to look at the very tenuous atmosphere," says co-author Ulli Käufl. The observations are part of a campaign that also includes a study of Pluto [eso0908]. Pluto, often considered a cousin of Triton and with similar conditions, is receiving renewed interest in the light of the carbon monoxide discovery, and astronomers are racing to find this chemical on the even more distant dwarf planet. This is just the first step for astronomers using CRIRES to understand the physics of distant bodies in the Solar System. "We can now start monitoring the atmosphere and learn a lot about the seasonal evolution of Triton over decades," Lellouch says. Notes [1] Triton is the only large moon in the Solar System with a retrograde motion, which is a motion in the opposite direction to its planet's rotation. This is one of the reasons why Triton is thought to have been captured from the Kuiper Belt, and thus shares many features with the dwarf planets, such as Pluto. More information This research was presented in a paper to appear in Astronomy & Astrophysics ("Detection of CO in Triton's atmosphere and the nature of surface-atmosphere interactions", by E. Lellouch et al.), reference DOI : 10.1051/0004-6361/201014339. The team is composed of E. Lellouch, C. de Bergh, B. Sicardy (LESIA, Observatoire de Paris, France), S. Ferron (ACRI-ST, Sophia-Antipolis, France), and H.-U. Käufl (ESO). ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and VISTA, the world's largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".

Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces

NASA Astrophysics Data System (ADS)

Plane, John M. C.; Flynn, George J.; Määttänen, Anni; Moores, John E.; Poppe, Andrew R.; Carrillo-Sanchez, Juan Diego; Listowski, Constantino

2018-02-01

Recent advances in interplanetary dust modelling provide much improved estimates of the fluxes of cosmic dust particles into planetary (and lunar) atmospheres throughout the solar system. Combining the dust particle size and velocity distributions with new chemical ablation models enables the injection rates of individual elements to be predicted as a function of location and time. This information is essential for understanding a variety of atmospheric impacts, including: the formation of layers of metal atoms and ions; meteoric smoke particles and ice cloud nucleation; perturbations to atmospheric gas-phase chemistry; and the effects of the surface deposition of micrometeorites and cosmic spherules. There is discussion of impacts on all the planets, as well as on Pluto, Triton and Titan.

Small planetary missions for the Space Shuttle

NASA Technical Reports Server (NTRS)

Staehle, R. L.

1979-01-01

The paper deals with the concept of a small planetary mission that might be described as one which: (1) focuses on a narrow set of discovery-oriented objectives, (2) utilizes largely existing and proven subsystem capabilities, (3) does not tax future launch vehicle capabilities, and (4) is flexible in terms of mission timing such that it can be easily integrated with launch vehicle schedules. Three small planetary mission concepts are presented: a tour of earth-sun Lagrange regions in search of asteroids which might be gravitationally trapped, a network of spacecraft to search beyond Pluto for a tenth planet; and a probe which could be targeted for infrequent long period 'comets of opportunity' or for a multitude of shorter period comets.

Past epochs of significantly higher pressure atmospheres on Pluto

NASA Astrophysics Data System (ADS)

Stern, S. A.; Binzel, R. P.; Earle, A. M.; Singer, K. N.; Young, L. A.; Weaver, H. A.; Olkin, C. B.; Ennico, K.; Moore, J. M.; McKinnon, W. B.; Spencer, J. R.; New Horizons Geology; Geophysics; Atmospheres Teams

2017-05-01

Pluto is known to have undergone thousands of cycles of obliquity change and polar precession. These variations have a large and corresponding impact on the total average solar insolation reaching various places on Pluto's surface as a function of time. Such changes could produce dramatic increases in surface pressure and may explain certain features observed by New Horizons on Pluto's surface, including some that indicate the possibility of surface paleo-liquids. This paper is the first to discuss multiple lines of geomorphological evidence consistent with higher pressure epochs in Pluto's geologic past, and it also the first to provide a mechanism for potentially producing the requisite high pressure conditions needed for an environment that could support liquids on Pluto. The presence of such liquids and such conditions, if borne out by future work, would fundamentally affect our view of Pluto's past climate, volatile transport, and geological evolution. This paper motivates future, more detailed climate modeling and geologic interpretation efforts in this area.

Epimetheus Above the Rings

NASA Image and Video Library

2015-11-09

Although Epimetheus appears to be lurking above the rings here, it's actually just an illusion resulting from the viewing angle. In reality, Epimetheus and the rings both orbit in Saturn's equatorial plane. Inner moons and rings orbit very near the equatorial plane of each of the four giant planets in our solar system, but more distant moons can have orbits wildly out of the equatorial plane. It has been theorized that the highly inclined orbits of the outer, distant moons are remnants of the random directions from which they approached the planets they orbit. This view looks toward the unilluminated side of the rings from about -0.3 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 26, 2015. The view was obtained at a distance of approximately 500,000 miles (800,000 kilometers) from Epimetheus and at a Sun-Epimetheus-spacecraft, or phase, angle of 62 degrees. Image scale is 3 miles (5 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18342

Former 9th and possible future 9th planet in the Solar system

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.

2016-12-01

4 terrestrial planets and 4 giant planets were formed in the Solar system. The Main asteroid belt is located between them, and the Kuiper belt and Oort cloud are located beyond the giant planets. Therefore, the planetary system is surrounded by a swarm of rocky-icy bodies up to a distance of 105 AU. The former 9th planet in the Solar system, Pluto, is the first known object of the Kuiper Belt. Due to data from the spacecraft "New Horizons" we made significant progress in the study of the physical characteristics of the object and its surface. Numerous observations have shown that the Kuiper belt itself is dynamically stable. And the source of cometary nuclei is a disk scattered by the gravitational perturbation of the giant planets more than 4 billion years ago. Recently, it was reported on indirect evidence of the existence of a new 9th planet in the Solar system with a mass 10 times greater than the mass of the Earth, a distance from the Sun ∼200 AU at perihelion, 600-1200 AU at aphelion, and an orbital period of ∼15000 years. These conclusions are based on the calculation of the orbits of 6 presently known objects of the scattered disc. We pay attention that, in moments close to their discovery, they were located near the perihelion, had a maximum brightness and a maximum orbital velocity. On the basis of probabilistic assumptions, we estimated that the probable number of the same bodies with eccentric orbits should be estimated at many thousands rather than at a few. For the initial evaluation, we used observational data from the Infrared Space Telescope "WISE". They showed that any Saturn's analog has not been registered at distances up to 30 000 AU. Therefore, a super-Earth with a radius of <11000 km (with a mass of ∼10 Earth masses) would have been seen at a distance up to 1000 AU. Thus, either unknown 9th planet is now at a greater distance, or these results cannot be directly scaled to the super-Earth with a disproporti! onately lower internal heat reserves.

Pluto: A Global Perspective

NASA Image and Video Library

2016-05-02

NASA New Horizons mission science team has produced this updated panchromatic black-and-white global map of Pluto. The map includes all resolved images of Pluto surface acquired between July 7-14, 2015.

Seasonal Nitrogen Cycles on Pluto

NASA Technical Reports Server (NTRS)

Hansen, Candice J.; Paige, David A.

1996-01-01

A thermal model, developed to predict seasonal nitrogen cycles on Triton, has been modified and applied to Pluto. The model was used to calculate the partitioning of nitrogen between surface frost deposits and the atmosphere, as a function of time for various sets of input parameters. Volatile transport was confirmed to have a significant effect on Pluto's climate as nitrogen moved around on a seasonal time scale between hemispheres, and sublimed into and condensed out of the atmosphere. Pluto's high obliquity was found to have a significant effect on the distribution of frost on its surface. Conditions that would lead to permanent polar caps on Triton were found to lead to permanent zonal frost bands on Pluto. In some instances, frost sublimed from the middle of a seasonal cap outward, resulting in a "polar bald spot". Frost which was darker than the substrate did not satisfy observables on Pluto, in contrast to our findings for Triton. Bright frost (brighter than the substrate) came closer to matching observables. Atmospheric pressure varied seasonally. The amplitudes, and to a lesser extent the phase, of the variation depended significantly on frost and substrate properties. Atmospheric pressure was found to be determined both by Pluto's distance from the sun and by the subsolar latitude. In most cases two peaks in atmospheric pressure were observed annually: a greater one associated with the sublimation of the north polar cap just as Pluto receded from perihelion, and a lesser one associated with the sublimation of the south polar cap as Pluto approached perihelion. Our model predicted frost-free dark substrate surface temperatures in the 50 to 60 K range, while frost temperatures typically ranged between 30 to 40 K. Temporal changes in frost coverage illustrated by our results, and changes in the viewing geometry of Pluto from the Earth, may be important for interpretation of ground-based measurements of Pluto's thermal emission.

Pluto in Hi-Def

NASA Image and Video Library

2008-01-24

This image demonstrates the first detection of Pluto using the high-resolution mode on the NASA New Horizons Long-Range Reconnaissance Imager. The mode provides a clear separation between Pluto and numerous nearby background stars.

Map of Pluto Surface

NASA Image and Video Library

1998-03-28

This image-based surface map of Pluto was assembled by computer image processing software from four separate images of Pluto disk taken with the European Space Agency Faint Object Camera aboard NASA Hubble Space Telescope.

Direct imaging search for the "missing link" in giant planet formation

NASA Astrophysics Data System (ADS)

Ngo, Henry; Mawet, Dimitri; Ruane, Garreth; Xuan, Wenhao; Bowler, Brendan; Cook, Therese; Zawol, Zoe

2018-01-01

While transit and radial velocity detection techniques have probed giant planet populations at close separations (within a few au), current direct imaging surveys are finding giant planets at separations of 10s-100s au. Furthermore, these directly imaged planets are very massive, including some with masses above the deuterium burning limit. It is not certain whether these objects represent the high mass end of planet formation scenarios or the low mass end of star formation. We present a direct imaging survey to search for the "missing link" population between the close-in RV and transiting giant planets and the extremely distant directly imaged giant planets (i.e. giant planets between 5-10 au). Finding and characterizing this population allows for comparisons with the formation models of closer-in planets and connects directly imaged planets with closer-in planets in semi-major axis phase space. In addition, microlensing surveys have suggested a large reservoir of giant planets exist in this region. To find these "missing link" giant planets, our survey searches for giant planets around M-stars. The ubiquity of M-stars provide a large number of nearby targets and their L-band contrast with planets allow for sensitivities to smaller planet masses than surveys conducted at shorter wavelengths. Along with careful target selection, we use Keck's L-band vector vortex coronagraph to enable sensitivities of a few Jupiter masses as close as 4 au to their host stars. We present our completed 2-year survey targeting 200 young (10-150 Myr), nearby M-stars and our ongoing work to follow-up over 40 candidate objects.

Pluto's Atmospheric Figure from the P131.1 Stellar Occultation

NASA Astrophysics Data System (ADS)

Person, M. J.; Elliot, J. L.; Clancy, K. B.; Kern, S. D.; Salyk, C. V.; Tholen, D. J.; Pasachoff, J. M.; Babcock, B. A.; Souza, S. P.; Ticehurst, D. R.; Hall, D.; Roberts, L. C., Jr.; Bosh, A. S.; Buie, M. W.; Dunham, E. W.; Olkin, C. B.; Taylor, B.; Levine, S. E.; Eikenberry, S. S.; Moon, D.-S.; Osip, D. J.

2003-05-01

The stellar occultation by Pluto of the 15th magnitude star designated P131.1 (McDonald and Elliot, AJ, 119, 1999) on 2002 August 21 (UT) provided the first significant chance to compare Pluto's atmospheric structure to that determined from the 1988 occultation of P8 (Millis, et al., Icarus, 105, 282). The P131.1 occultation was observed from several stations in Hawaii and the western United States (Elliot et al., Nature, in press, 2003). Numerous occultation chords were obtained enabling us to examine Pluto's atmospheric figure. The light curves from the observations were analyzed together in the occultation coordinate system of Elliot et al., (AJ, 106, 2544). The Mauna Kea and Lick datasets straddle the center of Pluto's figure, providing strong constraints on model fits to cross sections of the atmospheric shape. In 1988, Millis (et al., Icarus, 105, 282) did not report any deviation from sphericity in Pluto's atmospheric figure. From the 2002 data, Pluto;s isobars at the radii probed by the occultation ( 1250 km) appear to be distorted from a circular cross-section. Least-squares fits to this cross-section by elliptical models reveal ellipticities in the range 0.05-0.08 although the shape may be more complex than ellipsoidal. The orientation of the distortion appears uncorrelated with Pluto;s rotational axis. Taken at face value, this ellipticity could imply wind speeds of up to twice the sonic speed ( 200 m/s), which would be difficult to explain. Similar distortions have been reported for Triton's atmosphere (Elliot, J. L., et al., Icarus 148, 347). This work has been supported in part by Research Corporation, the Air Force Research Laboratory, NSF, and NASA.

Pluto and Charon: Surface Colors and Compositions - A Hypothesis

NASA Technical Reports Server (NTRS)

Cruikshank, D. P.

2016-01-01

The surface of Pluto displays an array of colors ranging from yellow to red to brown, while the surface of Charon is largely gray with a north polar zone of red color similar to regions on Pluto. Pluto's surface shows layers of intensely colored material in tilted and transported blocks, and fractured geo-graphical units. This arrangement suggests episodes of formation or deposition of that material interspersed with episodes of emplacement of ices having little or no color. The ices identified on the surfaces of these two bodies (N2, CH4, CO, C2H6, H2O on Pluto, and H2O and NH3 on Charon) are colorless, as are nearly all ices in a powdery state. The colors on Pluto probably arise from the in situ formation of a macro-molecular carbonaceous material generated by energetic processing of the ices on the surface. Laboratory experiments producing refractory tholins particularly relevant to Pluto explored the chemistry of both UV and low-energy electron bombardment of a mix of Pluto ices (N2:CH4:CO = 100:1:1). We can term this Pluto ice tholin PIT. Water ice in the crystalline state characterizes Charon's surface, and while most of Charon's surface is neutral in color, with geometric albedo approximately 0.38, the polar zone and a light cover of fainter but similar reddish color over some surface regions suggest a common origin with the colored material on Pluto. NH3 or NH3 x nH2O was identified from disk-integrated Earth-based spectra, and a few concentrated NH3 exposures have been found in the New Horizons spectral images.

Determination of the Charon/Pluto Mass Ratio from Center-of-Light Astrometry

NASA Technical Reports Server (NTRS)

Foust, Jeffrey A.; Elliot, J. L.; Olkin, Catherine B.; McDonald, Stephen W.; Dunham, Edward W.; Stone, Remington P. S.; McDonald, John S.; Stone, Ronald C.

1997-01-01

The Charon/Pluto mass ratio is a fundamental but poorly known parameter of the two-body system. Previous values for the mass ratio have ranged from 0.0837 plus or minus 0.0147 (Null et al., 1993, Astron. J. 105, 2319-2335) to 0.1566 plus or minus 0.0035 (Young et al., 1994, Icarus 108,186-199). We report here a new determination of the Charon/Pluto mass ratio, using five sets of groundbased images taken at four sites in support of Pluto occultation predictions. Unlike the Null et al. and Young et A determinations, where the centers of light for Pluto and Charon could be determined separately, this technique examines the motion of the center of light of the blended Pluto-Charon image. We compute the offsets of the observed center-of-light position of Pluto-Charon from the ephemeris position of the system and fit these offsets to a model of the Pluto-Charon system. The least-squares fits to the five data sets agree within their errors, and the weighted mean mass ratio is 0.117 plus or minus 0.006. The effects of errors in the Charon light fraction, semimajor axis, and ephemeris have been examined and are equal to only a small fraction of the formal error from the fit. This result is intermediate between those of Null et al., and Young et al. and matches a new value of 0.124 plus or minus 0.008 by Null and Owen (1996, Astron. J. 111, 1368-1381). The mass ratio and resulting individual masses and densities of Pluto and Charon are consistent with a collisional origin for the Pluto-Charon system.

Constraints on Pluto's Hazes from 2-Color Occultation Lightcurves

NASA Astrophysics Data System (ADS)

Hartig, Kara; Barry, T.; Carriazo, C. Y.; Cole, A.; Gault, D.; Giles, B.; Giles, D.; Hill, K. M.; Howell, R. R.; Hudson, G.; Loader, B.; Mackie, J. A.; Olkin, C. B.; Rannou, P.; Regester, J.; Resnick, A.; Rodgers, T.; Sicardy, B.; Skrutskie, M. F.; Verbiscer, A. J.; Wasserman, L. H.; Watson, C. R.; Young, E. F.; Young, L. A.; Buie, M. W.; Nelson, M.

2015-11-01

The controversial question of aerosols in Pluto's atmosphere first arose in 1988, when features in a Pluto occultation lightcurve were alternately attributed to haze opacity (Elliot et al. 1989) or a thermal inversion (Eshleman 1989). A stellar occultation by Pluto in 2002 was observed from several telescopes on Mauna Kea in wavelengths ranging from R- to K-bands (Elliot et al. 2003). This event provided compelling evidence for haze on Pluto, since the mid-event baseline levels were systematically higher at longer wavelengths (as expected if there were an opacity source that scattered more effectively at shorter wavelengths). However, subsequent occultations in 2007 and 2011 showed no significant differences between visible and IR lightcurves (Young et al. 2011).The question of haze on Pluto was definitively answered by direct imaging of forward-scattering aerosols by the New Horizons spacecraft on 14-JUL-2015. We report on results of a bright stellar occultation which we observed on 29-JUN-2015 in B- and H-bands from both grazing and central sites. As in 2007 and 2011, we see no evidence for wavelength-dependent extinction. We will present an analysis of haze parameters (particle sizes, number density profiles, and fractal aggregations), constraining models of haze distribution to those consistent with and to those ruled out by the occultation lightcurves and the New Horizons imaging.References:Elliot, J.L., et al., "Pluto's Atmosphere." Icarus 77, 148-170 (1989)Eshleman, V.R., "Pluto's Atmosphere: Models based on refraction, inversion, and vapor pressure equilibrium." Icarus 80 439-443 (1989)Elliot, J.L., et al., "The recent expansion of Pluto's atmosphere." Nature 424 165-168 (2003)Young, E.F., et al., "Search for Pluto's aerosols: simultaneous IR and visible stellar occultation observations." EPSC-DPS Joint Meeting 2011, held 2-7 October 2011 in Nantes, France (2011)

Destination pluto: New horizons performance during the approach phase

NASA Astrophysics Data System (ADS)

Flanigan, Sarah H.; Rogers, Gabe D.; Guo, Yanping; Kirk, Madeline N.; Weaver, Harold A.; Owen, William M.; Jackman, Coralie D.; Bauman, Jeremy; Pelletier, Frederic; Nelson, Derek; Stanbridge, Dale; Dumont, Phillip J.; Williams, Bobby; Stern, S. Alan; Olkin, Cathy B.; Young, Leslie A.; Ennico, Kimberly

2016-11-01

The New Horizons spacecraft began its journey to the Pluto-Charon system on January 19, 2006 on-board an Atlas V rocket from Cape Canaveral, Florida. As the first mission in NASA's New Frontiers program, the objective of the New Horizons mission is to perform the first exploration of ice dwarfs in the Kuiper Belt, extending knowledge of the solar system to include the icy "third zone" for the first time. Arriving at the correct time and correct position relative to Pluto on July 14, 2015 depended on the successful execution of a carefully choreographed sequence of events. The Core command sequence, which was developed and optimized over multiple years and included the highest-priority science observations during the closest approach period, was contingent on precise navigation to the Pluto-Charon system and nominal performance of the guidance and control (G&C) subsystem. The flyby and gravity assist of Jupiter on February 28, 2007 was critical in placing New Horizons on the path to Pluto. Once past Jupiter, trajectory correction maneuvers (TCMs) became the sole source of trajectory control since the spacecraft did not encounter any other planetary bodies along its flight path prior to Pluto. During the Pluto approach phase, which formally began on January 15, 2015, optical navigation images were captured primarily with the Long Range Reconnaissance Imager to refine spacecraft and Pluto-Charon system trajectory knowledge, which in turn was used to design TCMs. Orbit determination solutions were also used to update the spacecraft's on-board trajectory knowledge throughout the approach phase. Nominal performance of the G&C subsystem, accurate TCM designs, and high-quality orbit determination solutions resulted in final Pluto-relative B-plane arrival conditions that facilitated a successful first reconnaissance of the Pluto-Charon system.

The Orbits and Masses of Pluto's Satellites

NASA Astrophysics Data System (ADS)

Jacobson, Robert A.; Brozovic, M.

2012-10-01

We have fit numerically integrated orbits of Pluto's satellites, Charon, Nix, Hydra, and S/2011 (134340) 1, to an extensive set of astrometric, mutual event, and stellar occultation observations over the time interval April 1965 to July 2011. We did not include the newly discovered satellite S/2012 (134340) 1 because its observation set is insufficient to constrain a numerically integrated orbit. The data set contains all of the HST observations of Charon relative to Pluto which have been corrected for the Pluto center-of-figure center-of-light (COF) offset due to the Pluto albedo variations (Buie et al. 2012 AJ submitted). Buie et al. (2010 AJ 139, 1117 and 1128) discuss the development of the albedo model and the COF offset. We applied COF offset corrections to the remainder of the Pluto relative observations where applicable. The dual stellar occultations in 2008 and 2011 provided precise Pluto_Charon relative positions. We obtain a well determined value for the Pluto system mass, however, the lack of orbital resonances in the system makes it difficult to determine the satellite masses. The primary source of information for the Charon mass is a small quantity of absolute position measurements which are sensitive to the independent motions of Pluto and Charon about the system barycenter. The long term dynamical interaction among the satellites yields a weak determination of Hydra's mass; the masses of the other two satellites are found to be small but indeterminate. We have delivered ephemerides based on our integrated orbits to the New Horizons project along with their expected uncertainties at the time of the New Horizons encounter with the Pluto system. Acknowledgments: The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Inhibition of the electron cyclotron maser instability in the dense magnetosphere of a hot Jupiter

NASA Astrophysics Data System (ADS)

Daley-Yates, S.; Stevens, I. R.

2018-06-01

Hot Jupiter (HJ) type exoplanets are expected to produce strong radio emission in the MHz range via the Electron Cyclotron Maser Instability (ECMI). To date, no repeatable detections have been made. To explain the absence of observational results, we conduct 3D adaptive mess refinement (AMR) magnetohydrodynamic (MHD) simulations of the magnetic interactions between a solar type star and HJ using the publicly available code PLUTO. The results are used to calculate the efficiency of the ECMI at producing detectable radio emission from the planets magnetosphere. We also calculate the frequency of the ECMI emission, providing an upper and lower bounds, placing it at the limits of detectability due to Earth's ionospheric cutoff of ˜10 MHz. The incident kinetic and magnetic power available to the ECMI is also determined and a flux of 0.075 mJy for an observer at 10 pc is calculated. The magnetosphere is also characterized and an analysis of the bow shock which forms upstream of the planet is conducted. This shock corresponds to the thin shell model for a colliding wind system. A result consistent with a colliding wind system. The simulation results show that the ECMI process is completely inhibited by the planets expanding atmosphere, due to absorption of UV radiation form the host star. The density, velocity, temperature and magnetic field of the planetary wind are found to result in a magnetosphere where the plasma frequency is raised above that due to the ECMI process making the planet undetectable at radio MHz frequencies.

Other Planetary Systems: The View From Our Neighborhood

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.; Witteborn, Fred C. (Technical Monitor)

1995-01-01

The structure and contents of the Solar System offer an initial model for other planetary systems in this and other galaxies. Our knowledge of the bodies in the Solar System and their physical conditions has grown enormously in the three decades of planetary exploration. Parallel to the uncovering of new facts has been a great expansion of our understanding of just how these conditions came to be. Telescopic studies and missions to all the planets (except Pluto) have shown spectacular and unexpected diversity among those planets, their satellites, the asteroids, and the comets. Highlights include the organic-rich crust of comets, volcanic activity on planetary satellites, randomly oriented magnetic fields of the major planets, the existence of a huge population of planetesimals just beyond Neptune, dramatic combinations of exogenic and endogenic forces shaping the solid bodies throughout the Solar System, and much more. Simultaneously, computational, laboratory, and conceptual advances have shown that the Solar System is not fully evolved either dynamically or chemically. The discovery of clearly identified interstellar (presolar) material in the meteorites and comets connects us directly with the matter in the molecular cloud from which the Solar System originated. At the same time, an increased understanding of the chemistry of comets and the impact history of the planets has demonstrated the dependence of the origin and evolution of life on Earth on powerful exogenic factors. This presentation summarizes some of the new knowledge of the Solar System and proposes specific character ist ics that may be observed in (or used as criteria for identification of) extrasolar planetary systems.

Missions to the Outer Solar System and Beyond - Concept Study for a Kuiper Belt Sample-Return

NASA Astrophysics Data System (ADS)

Ganapathy, Rohan M.

The exploration of Kuiper belt objects (KBOs) might deliver crucial data for answering questions about the evolution of the solar system and the origin of life. Whereas the current New Horizons mission performs a flyby at KBOs, an in-depth exploration of the Kuiper belt requires an orbiter, lander or even a sample return. In this paper, we present a range of potential mission architectures for a Kuiper belt sample return mission. We use the Systems Modeling Language (SysML) for the necessary modeling and the systems engineering tool MagicDraw. A process similar to the NASA Rapid Mission Architecture approach was used. We start with a rationale a KBO sample return, dene science objectives, high-level requirements and select a strawman payload. From a key trade-matrix, mission architecture options are generated. Finally, necessary technologies and prerequisites for the mission are identied. We conclude that one of the dwarf planets Pluto, Haumea, Orcus or Quaoar and their moons should be considered as a target for the mission. The samples should be collected from the dwarf planet of choice or from its moon(s), which omits the rather high velocity requirements for a landing and departure from the dwarf planet itself. Attractive mission architectures include radioisotopic electric propulsion-based missions, missions with a combination of a solar electric propulsion stage and radioisotopic electric propulsion, or missions using nuclear electric propulsion.

Orbital Modification of the Himalia Family during an Early Solar System Dynamical Instability

NASA Astrophysics Data System (ADS)

Li, Daohai; Christou, Apostolos A.

2017-11-01

Among the irregular satellites orbiting Jupiter, the Himalia family is characterized by a high velocity dispersion δ v of several hundred {{m}} {{{s}}}-1 among its members, inconsistent with a collisional origin. Efforts to account for this through internecine gravitational interactions do not readily reproduce this feature. Here, we revisit the problem in the context of recent cosmogonical models, where the giant planets migrated significantly through interaction with a planetesimal disk and suffered encounters with planetesimals and planet-sized objects. Our starting assumption is that family formation either predated this phase or occurred soon after its onset. We simulate numerically the diffusive effect of three distinct populations of perturbers on a set of test particles representing the family: Moon-sized (MPT) and Pluto-sized (PPT) planetesimals, and planetary-mass objects (PMO) with masses typical of ice-giant planets. We find that PPT flybys are inefficient, but encounters with MPTs raise the δ v of ∼60% of our test particles to > 200 {{m}} {{{s}}}-1 with respect to Himalia, in agreement with observations. As MPTs may not have been abundant in the disk, we simulate encounters between Jupiter and PMOs. We find that too few encounters generate less dispersion than MPTs while too many essentially destroy the family. For PMO masses in the range 5{--}20 {m}\\oplus , the family orbital distribution is reproduced by a few tens of encounters.

Observational Limits for Rings and Debris at Pluto from New Horizons

NASA Astrophysics Data System (ADS)

Throop, Henry B.; Lauer, Tod R.; Showalter, Mark R.; Weaver, Harold A.; Stern, S. Alan; Spencer, John R.; Buie, Marc W.; Hamilton, Douglas P.; Porter, Simon Bernard; Verbiscer, Anne J.; Young, Leslie; Olkin, Catherine; Ennico, Kimberly; New Horizons Science Team

2017-10-01

NASA's New Horizons missions flew past Pluto on July 14, 2015. New Horizons conducted an extensive search for orbital material at Pluto, using deep imaging at backscatter and forward-scatter, direct in situ dust detector measurements, and stellar occultations. We searched the entire region from the surface of Pluto outward to the Pluto-Charon Hill radius (6.4 x 106 km = 100 times Hydra's orbital radius), using the spacecraft's LORRI and MVIC cameras.No material was found to a normal I/F limit of 2 x 10-8 for 1500 km-wide rings, and 7 x 10-9 for 12,000 km-wide rings. Our results are consistent with dynamical studies that show the lifetime of dust in the Pluto system is short, with the loss dominated by solar radiation pressure and gravitational perturbations.

Chasing Shadows

ERIC Educational Resources Information Center

DeVore, Edna; Gould, Alan

2017-01-01

The solar eclipse coming August 21 offers students the opportunity not only to explore the geometry of the solar system but also to learn about exoplanets transiting distant stars. Students can glimpse a great frontier of science: the search for other worlds and life. This article presents information on exoplanets, discovering planets around…

Visible and infrared investigations of planet-crossing asteroids and outer solar system objects

NASA Technical Reports Server (NTRS)

Tholen, David J.

1991-01-01

The project is supporting lightcurve photometry, colorimetry, thermal radiometry, and astrometry of selected asteroids. Targets include the planet-crossing population, particularly Earth approachers, which are believed to be the immediate source of terrestrial meteorites, future spacecraft targets, and those objects in the outer belt, primarily the Hilda and Trojan populations, that are dynamically isolated from the main asteroid belt. Goals include the determination of population statistics for the planet-crossing objects, the characterization of spacecraft targets to assist in encounter planning and subsequent interpretation of the data, a comparison of the collisional evolution of dynamically isolated Hilda and Trojan populations with the main belt, and the determination of the mechanism driving the activity of the distant object 2060 Chiron.

Grounded Eyes on Distant Watery Skies

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-08-01

What can we learn about exoplanets from high-resolution, ground-based observations? A new view of the nearby upsilon Andromedae system has revealed a great deal about the systems closest-in exoplanet including the presence of water vapor in its atmosphere.Search for WobblesIllustration of how spectral lines shift when observing two objects that orbit each other. Click here to see a simulation of this process. [R. Pogge, OSU]The upsilon Andromedae system is located roughly 44 light-years from Earth. In 1997, a hot Jupiter exoplanet was discovered orbiting the primary star, and more planets were found not long after making this the first multiple-planet system discovered around a main-sequence star.These planets, however, were not discovered due to transits; their orbital planes are not aligned with our line of sight to the star. Instead, the hiddenplanets were first detected via the stars spectrum. The radial velocity method of detecting exoplanets searches for telltale periodic shifts of a stars spectral lines, which are induced by the orbiting planets gravitational tugs.In recent years, ground-based spectroscopy has become ever more powerful; thus revisiting old systems with higher resolution instruments can often open a whole new world of data to us. In the case of a recent study, a team of astronomers led by Danielle Piskorz (California Institute of Technology) revisited upsilon Andromedae with the high-resolution Near Infrared Spectrometer (NIRSPEC) at the Keck telescope in Hawaii. Their goal: to gather data about upsilon Andromedae b, the closest-in planet in the system.Top-down schematic of the orbit of upsilon Andromedae b around its star and the location in the orbit of the authors observations. [Piskorz et al. 2017]An Unusual ArchitecturePiskorz and collaborators obtained 13 different sets of observations of upsilon Andromedae with NIRSPEC across three different wavelength bands. By treating the starplanet system as though it were a spectroscopic binary, the authorshigh-resolution observations allowed them to resolve not only the stellar spectrum, but also the spectral lines fromthe hot Jupiter exoplanet itself.Obtaining a thermal spectrum of the planet permitted the team to break the usual observational degeneracy that occurs with exoplanet observations: they were able to disentangle the planet mass and its orbital inclination angle. Piskorz and collaborators found that the planet is roughly 1.7 Jupiter masses and its orbit is inclined 24 relative to our line of sight.Artists illustration of the closest three planets in the upsilon Andromedae system. The system also has a distant red-dwarf binary companion, as well as a possible fourth planet. [NASA/ESA/A. Feild (STScI)]These measurements of the orbital structure of upsilon Andromedae are critical for understanding this unusual system. With non-coplanar planets and a distant red-dwarf companion, the upsilon Andromedae system has long been suspected to lie on the precipice of instability. The new measurements of upsilon Andromeda bs orbital properties will help us to better understand how the system may have formed, evolved, and survived to today.Water FoundOne of the biggest benefits of spectroscopy of an exoplanet is the potentialto learn about its atmospheric composition. Using their NIRSPEC observations of upsilon Andromedae b and detailed atmospheric modeling, Piskorz and collaborators found that the planets opacity structure is dominated by water vapor at the wavelengths they probed.This detection of water vapor in upsilon Andromedae bs atmosphere and the constraints on the planets orbital properties demonstrate the power and potential of ground-based, high-resolution spectroscopy for characterizing exoplanets and constraining the architecture of distantsolar systems.CitationDanielle Piskorz et al 2017 AJ 154 78. doi:10.3847/1538-3881/aa7dd8

Map of Exoplanets Found in Our Galaxy Artist Concept

NASA Image and Video Library

2015-04-14

Astronomers have discovered one of the most distant planets known, a gas giant about 13,000 light-years from Earth, called OGLE-2014-BLG-0124L. The planet was discovered using a technique called microlensing, and the help of NASA's Spitzer Space Telescope and the Optical Gravitational Lensing Experiment, or OGLE. In this artist's illustration, planets discovered with microlensing are shown in yellow. The farthest lies in the center of our galaxy, 25,000 light-years away. Most of the known exoplanets, numbering in the thousands, have been discovered by NASA's Kepler space telescope, which uses a different strategy called the transit method. Kepler's cone-shaped field of view is shown in pink/orange. Ground-based telescopes, which use the transit and other planet-hunting methods, have discovered many exoplanets close to home, as shown by the pink/orange circle around the sun. http://photojournal.jpl.nasa.gov/catalog/PIA19333

Radio Occultation Measurements of Pluto's Atmosphere with New Horizons

NASA Astrophysics Data System (ADS)

Hinson, D. P.; Linscott, I.; Tyler, G. L.; Bird, M. K.; Paetzold, M.; Strobel, D. F.; Summers, M. E.; Woods, W. W.; Stern, A.; Weaver, H. A., Jr.; Olkin, C.; Young, L. A.; Ennico Smith, K.; Gladstone, R.; Greathouse, T.; Kammer, J.; Parker, A. H.; Parker, J. W.; Retherford, K. D.; Schindhelm, E.; Singer, K. N.; Steffl, A.; Tsang, C.; Versteeg, M.

2015-12-01

The reconnaissance of the Pluto System by New Horizons included radio occultations at both Pluto and Charon. This talk will present the latest results from the Pluto occultation. The REX instrument onboard New Horizons received and recorded uplink signals from two 70-m antennas and two 34-m antennas of the NASA Deep Space Network - each transmitting 20 kW at 4.2-cm wavelength - during a diametric occultation by Pluto. At the time this was written only a short segment of data at occultation entry (193°E, 17°S) was available for analysis. The REX measurements extend unequivocally to the surface, providing the first direct measure of the surface pressure and the temperature structure in Pluto's lower atmosphere. Preliminary analysis yields a surface pressure of about 10 microbars, smaller than expected. Data from occultation exit (16°E, 15°N) are scheduled to arrive on the ground in late August 2015. Those observations will yield an improved estimate of the surface pressure, a second temperature profile, and a measure of the diameter of Pluto with a precision of a few hundred meters.

Discovery of two new satellites of Pluto.

PubMed

Weaver, H A; Stern, S A; Mutchler, M J; Steffl, A J; Buie, M W; Merline, W J; Spencer, J R; Young, E F; Young, L A

2006-02-23

Pluto's first known satellite, Charon, was discovered in 1978. It has a diameter (approximately 1,200 km) about half that of Pluto, which makes it larger, relative to its primary, than any other moon in the Solar System. Previous searches for other satellites around Pluto have been unsuccessful, but they were not sensitive to objects less, similar150 km in diameter and there are no fundamental reasons why Pluto should not have more satellites. Here we report the discovery of two additional moons around Pluto, provisionally designated S/2005 P 1 (hereafter P1) and S/2005 P 2 (hereafter P2), which makes Pluto the first Kuiper belt object known to have multiple satellites. These new satellites are much smaller than Charon, with estimates of P1's diameter ranging from 60 km to 165 km, depending on the surface reflectivity; P2 is about 20 per cent smaller than P1. Although definitive orbits cannot be derived, both new satellites appear to be moving in circular orbits in the same orbital plane as Charon, with orbital periods of approximately 38 days (P1) and approximately 25 days (P2).

Occultation Lightcurves for Selected Pluto Volatile Transport Models

NASA Astrophysics Data System (ADS)

Young, L. A.

2004-11-01

The stellar occultations by Pluto in 1988 and 2002 are demonstrably sensitive to changes in Pluto's atmosphere near one microbar (Elliot and Young 1992, AJ 103, 991; Elliot et al. 2003, Nature 424, 165; Sicardy 2003, Nature 424, 168). However, Pluto volatile-transport models focus on the changes in the atmospheric pressure at the surface (e.g., Hansen and Paige 1996, Icarus 20, 247; Stansberry and Yelle 1999, Icarus 141, 299). What's lacking is a connection between predictions about the surface properties and either temperature and pressure profiles measurable from stellar occultations, or the occultation light curve morphology itself. Radiative-conductive models can illuminate this connection. I will illustrate how Pluto's changing surface pressure, temperature, and heliocentric distance may affect occultation light curves for a selection of existing volatile transport models. Changes in the light curve include the presence or absence of an observable ``kink'' (or departure from an isothermal light curve), the appearance of non-zero minimum flux levels, and the detectability of the solid surface. These light curves can serve as examples of what we may anticipate during the upcoming Pluto occultation season, as Pluto crosses the galactic plane.

K2 Finds Earth-Sized Planets Artist Concept

NASA Image and Video Library

2016-07-18

This artist's concept shows NASA's Kepler Space Telescope on its K2 mission. In July 2016, an international team of astronomers announced they had discovered more than 100 new planets using this telescope. The batch includes four planets in the size range of Earth that are orbiting a single dwarf star, depicted in this illustration. Two of these planets are too hot to support life as we know it, but two are in the star's "habitable" zone, where liquid water could exist on the surface. These small, rocky worlds are far closer to their star than Mercury is to our sun. But because the star is smaller and cooler than ours, its habitable zone is much closer. One of the two planets in the habitable zone, K2-72c, has a "year" about 15 Earth-days long -- the time it takes to complete one orbit. This closer planet is likely about 10 percent warmer than Earth. The slightly more distant planet in the habitable zone, K2-72e, has a year lasting 24 Earth days, and would be about 6 percent colder than Earth. http://photojournal.jpl.nasa.gov/catalog/PIA20698

Migration of icy planetesimals to forming terrestrial planets

NASA Astrophysics Data System (ADS)

Ipatov, Sergei I.; Marov, Mikhail

2016-07-01

Our studies of migration of planetesimals from the feeding zone of Jupiter and Saturn to forming terrestrial planets were based on computer simulations of the orbital evolution of 10^4 planetesimals under the gravitational influence of planets. In series JN, all planets were considered in present orbits with present masses, and in series JS, Uranus and Neptune were excluded. Initial eccentricities and inclinations of planetesimals were 0.3 and 0.15 rad, respectively. Their initial semi-major axes were between 4.5 and 12 AU. Masses of planets moving in the orbits of the terrestrial planets were equal to present masses of the planets in series JS and JN, and were smaller by a factor of 10 in series JS_{01} and JN_{01}. The obtained results show that the ratio of the fraction of the planetesimals collided with an embryo of the Earth's embryo was about 2\\cdot10^{-6} and 4\\cdot10^{-7} for the mass of the embryo equal to the Earth mass and to 10% of the Earth mass, respectively. We concluded that during the growth of the mass of the Earth's embryo up to a half of the present mass of the Earth, the amount of water delivered to the embryo could be about 30% of all water delivered to the Earth from the feeding zone of Jupiter and Saturn. The total mass of water delivered to the Earth from the feeding zones of the giant planets and beyond these zones could be comparable with the mass of the Earth's oceans. A half of this water could come from the feeding zone of Jupiter and Saturn, and another half from more distant regions. Most of the water that was delivered from the distant regions to the Earth's embryo came when its mass was not small (e.g., was mainly greater than a half of the Earth mass). In series JS, the ratio of the mass of water delivered to a planet to the mass of the planet for the Earth was smaller by a factor of 2, 1.25, and 1.3 than for Mars, Venus and Mercury, respectively. For series JN, the above values of the factor were equal to 3.4, 0.7 i 0.8. For the growth of the Earth's embryo of mass m by accretion of planetesimals that came from the feeding zone of Jupiter and Saturn, the increase of its mass was proportional to m^{0.74}.

Martin Brasier (1947-2014): astrobiologist

NASA Astrophysics Data System (ADS)

McMahon, Sean; Cockell, Charles

2015-10-01

How did life on Earth begin? What does the search for life in the distant past tell us about the search for life on distant planets? How should the most ancient and ambiguous putative biosignatures be critically evaluated? How did the Earth-life system evolve through the dramatic upheavals of the Precambrian-Cambrian boundary? When and why did eukaryotes begin to produce mineralized skeletons? These are among the astrobiological questions to which palaeobiologist Martin Brasier made profound contributions in a career spanning nearly half a century and tragically cut short late last year. Here, we summarize and celebrate Martin's contributions to astrobiology.

Pluto Big Heart in Color

NASA Image and Video Library

2015-07-14

Pluto nearly fills the frame in this image from NASA New Horizons spacecraft, taken on July 13, 2015. This is the last and most detailed image sent to Earth before the spacecraft closest approach to Pluto on July 14.

Pluto Bladed Terrain in 3-D

NASA Image and Video Library

2016-03-31

One of the strangest landforms spotted by NASA New Horizons spacecraft when it flew past Pluto last July was the bladed terrain just east of Tombaugh Regio, the informal name given to Pluto large heart-shaped surface feature.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quintana, Elisa V.; Lissauer, Jack J., E-mail: elisa.quintana@nasa.gov

Models of planet formation have shown that giant planets have a large impact on the number, masses, and orbits of terrestrial planets that form. In addition, they play an important role in delivering volatiles from material that formed exterior to the snow line (the region in the disk beyond which water ice can condense) to the inner region of the disk where terrestrial planets can maintain liquid water on their surfaces. We present simulations of the late stages of terrestrial planet formation from a disk of protoplanets around a solar-type star and we include a massive planet (from 1 Mmore » {sub ⊕} to 1 M {sub J}) in Jupiter's orbit at ∼5.2 AU in all but one set of simulations. Two initial disk models are examined with the same mass distribution and total initial water content, but with different distributions of water content. We compare the accretion rates and final water mass fraction of the planets that form. Remarkably, all of the planets that formed in our simulations without giant planets were water-rich, showing that giant planet companions are not required to deliver volatiles to terrestrial planets in the habitable zone. In contrast, an outer planet at least several times the mass of Earth may be needed to clear distant regions of debris truncating the epoch of frequent large impacts. Observations of exoplanets from radial velocity surveys suggest that outer Jupiter-like planets may be scarce, therefore, the results presented here suggest that there may be more habitable planets residing in our galaxy than previously thought.« less

ScienceCast 26: Visit to Pluto

NASA Image and Video Library

2011-09-02

Pluto is a world of mystery waiting to be visited for the 1st time. NASA's New Horizons probe is racing across the solar system for a close encounter that could alter what researchers "know" about Pluto and other small worlds.

Pluto in Twilight

NASA Image and Video Library

2015-09-10

This image of Pluto from NASA's New Horizons spacecraft, processed in two different ways, shows how Pluto's bright, high-altitude atmospheric haze produces a twilight that softly illuminates the surface before sunrise and after sunset, allowing the sensitive cameras on New Horizons to see details in nighttime regions that would otherwise be invisible. The right-hand version of the image has been greatly brightened to bring out faint details of rugged haze-lit topography beyond Pluto's terminator, which is the line separating day and night. The image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). http://photojournal.jpl.nasa.gov/catalog/PIA19931

NASA Researchers Discover “Bladed Terrain” on Pluto is Made of Frozen Methane (Video News File)

NASA Image and Video Library

2017-09-22

NASA has identified large formations of frozen methane on the surface of Pluto that are as tall as skyscrapers. Researchers at NASA’s Ames Research Center in Silicon Valley used high resolution maps from the New Horizons flyby of Pluto in 2015 to understand these dramatic structures. The “bladed terrain” occurs only at high altitudes and in the region around the equator of Pluto. These jagged spires are thought to be created by an erosion process as the methane ice sublimates into gas. Researchers hope to use their findings to fill in the details of the areas of Pluto that were only measured in low resolution.

Pluto behaving badly: false beliefs and their consequences.

PubMed

Berkowitz, Shari R; Laney, Cara; Morris, Erin K; Garry, Maryanne; Loftus, Elizabeth F

2008-01-01

We exposed college students to suggestive materials in order to lead them to believe that, as children, they had a negative experience at Disneyland involving the Pluto character. A sizable minority of subjects developed a false belief or memory that Pluto had uncomfortably licked their ear. Suggestions about a positive experience with Pluto led to even greater acceptance of a lovable ear-licking episode. False beliefs and memories had repercussions; those seduced by the bad suggestions were not willing to pay as much for a Pluto souvenir. These findings are among the first to demonstrate that false beliefs can have repercussions for people, meaning that they can influence their later thoughts, beliefs, and behaviors.

Volatile Transport in Pluto's Super Seasons

NASA Astrophysics Data System (ADS)

Earle, Alissa M.; Binzel, Richard; Young, Leslie; Stern, S. Alan; Olkin, Catherine B.; Ennico, Kimberly; Moore, Jeffrey M.; Weaver, Harold A.; NASA New Horizons Composition Team, The NASA New Horizons GGI Team

2016-10-01

The data returned from NASA's New Horizons' reconnaissance of the Pluto system shows striking albedo variations from polar to equatorial latitudes as well as sharp boundaries for longitudinal variations. Pluto has a high obliquity (currently around 119 degrees) which varies by more than 23 degrees (between roughly 103 and 127 degrees) over a period of less than 3 million years. These obliquity properties, combined with Pluto's orbital regression in longitude of perihelion (360 degrees over 3.7 million years), create epochs of "Super Seasons" on Pluto. A "Super Season" occurs, for example, when Pluto happens to be pole-on towards the Sun at the same time as perihelion. In such a case, one pole experiences a short, intense summer (relative to its long-term average) followed by a longer than average period of winter darkness. By complement, the other pole experiences a much longer, but less intense summer and short winter season. We explore the relationship between albedo variations and volatile transport for the current epoch as well as historical epochs during which Pluto experienced these "Super Seasons". Our investigation suggests Pluto's orbit creates the potential for runaway albedo variations, particularly in the equatorial region, which would create and support stark longitudinal contrasts like the ones we see between the informally named Tombaugh and Cthulhu Regios.This work was supported by the NASA New Horizons mission.

The State of Pluto's Bulk Atmosphere at the Time of the New Horizons Encounter

NASA Astrophysics Data System (ADS)

Resnick, Aaron C.; Barry, T.; Buie, M. W.; Carriazo, C. Y.; Cole, A.; Gault, D.; Giles, B.; Giles, D.; Hartig, K.; Hill, K.; Howell, R. R.; Hudson, G.; Loader, B.; Mackie, J.; Nelson, M.; Olkin, C.; Register, J.; Rodgers, T.; Sicardy, B.; Skrutskie, M.; Verbiscer, A.; Wasserman, L.; Watson, C.; Young, E.; Young, L.; Zalucha, A.

2015-11-01

On 29-JUL-2015, our team - plus many critical amateur astronomers - observed a stellar occultation by Pluto from sites in Australia and New Zealand. This event was remarkable for two reasons: it preceded the New Horizons flyby of Pluto by just two weeks, and the occulted star was about 10x brighter than Pluto itself, by far the brightest Pluto occultation event observed to date. The separation of ground sites spanned nearly 900 km with respect to the central chord, allowing a good geometric solution for the shadow path. The lightcurves show some inflection points and broad "fangs" that are characteristic of perturbations in the temperature profile. Preliminary fits show that the temperature profile derived from a 2006 occultation (Young et al. 2008) reproduces the 29-JUN-2015 lightcurves well. Assuming a surface radius of 1187 km for Pluto, we find that the surface pressure is 18 +/- 3 µbar. This pressure indicates that Pluto's surface has not yet started to cool down, despite a decrease in absorbed solar flux of more than 17% since perihelion in 1988. A surface pressure of 18 µbar would correspond to a nitrogen ice surface temperature of 38.0 K.References:Young, E.F., et al. "Vertical Structure in Pluto's Atmosphere from the 2006 June 12 Stellar Occultation," AJ 136 1757-1769 (2008)

The Search for Planet Nine

NASA Astrophysics Data System (ADS)

Brown, Michael E.; Batygin, Konstantin

2016-10-01

We use an extensive suite of numerical simulations to constrain the mass and orbit of Planet Nine, and we use these constraints to begin the search for this newly proposed planet in new and in archival data. Here, we compare our simulations to the observed population of aligned eccentric high semimajor axis Kuiper belt objects and determine which simulation parameters are statistically compatible with the observations. We find that only a narrow range of orbital elements can reproduce the observations. In particular, the combination of semimajor axis, eccentricity, and mass of Planet Nine strongly dictates the semimajor axis range of the orbital confinement of the distant eccentric Kuiper belt objects. Allowed orbits, which confine Kuiper belt objects with semimajor axis beyond 380 AU, have perihelia roughly between 150 and 350 AU, semimajor axes between 380 and 980 AU, and masses between 5 and 20 Earth masses. Orbitally confined objects also generally have orbital planes similar to that of the planet, suggesting that the planet is inclined approximately 30 degrees to the ecliptic. We compare the allowed orbital positions and estimated brightness of Planet Nine to previous and ongoing surveys which would be sensitive to the planet's detection and use these surveys to rule out approximately two-thirds of the planet's orbit. Planet Nine is likely near aphelion with an approximate brightness of 22

Blue Rays: New Horizons High-Res Farewell to Pluto

NASA Image and Video Library

2017-03-24

This is the highest-resolution color departure shot of Pluto's receding crescent from NASA's New Horizons spacecraft, taken when the spacecraft was 120,000 miles (200,000 kilometers) away from Pluto. Shown in approximate true color, the picture was constructed from a mosaic of six black-and-white images from the Long Range Reconnaissance Imager (LORRI), with color added from a lower resolution Ralph/Multispectral Visible Imaging Camera (MVIC) color image, all acquired between 15:20 and 15:45 UT -- about 3.5 hours after closest approach to Pluto -- on July 14, 2015. The resolution of the LORRI images is about 0.6 miles (1 kilometer) per pixel; the sun illuminates the scene from the other side of Pluto and somewhat toward the top of this image. The image is dominated by spectacular layers of blue haze in Pluto's atmosphere. Scientists believe the haze is a photochemical smog resulting from the action of sunlight on methane and other molecules in Pluto's atmosphere, producing a complex mixture of hydrocarbons such as acetylene and ethylene. These hydrocarbons accumulate into small haze particles, a fraction of a micrometer in size, which preferentially scatter blue sunlight -- the same process that can make haze appear bluish on Earth. As they settle down through the atmosphere, the haze particles form numerous intricate, horizontal layers, some extending for hundreds of miles around large portions of the limb of Pluto. The haze layers extend to altitudes of over 120 miles (200 kilometers). Pluto's circumference is 4,667 miles (7,466 kilometers). Adding to the beauty of this picture are mountains and other topographic features on Pluto's surface that are silhouetted against the haze near the top of the image. Sunlight casts dramatic and beautiful finger-like shadows from many of these features onto the haze (especially on the left, near the 11 o'clock position), forming crepuscular rays like those often seen in Earth's atmosphere near sunrise or sunset. https://photojournal.jpl.nasa.gov/catalog/PIA21590

Pluto in 3-D

NASA Image and Video Library

2015-10-23

Global stereo mapping of Pluto surface is now possible, as images taken from multiple directions are downlinked from NASA New Horizons spacecraft. Stereo images will eventually provide an accurate topographic map of most of the hemisphere of Pluto seen by New Horizons during the July 14 flyby, which will be key to understanding Pluto's geological history. This example, which requires red/blue stereo glasses for viewing, shows a region 180 miles (300 kilometers) across, centered near longitude 130 E, latitude 20 N (the red square in the global context image). North is to the upper left. The image shows an ancient, heavily cratered region of Pluto, dotted with low hills and cut by deep fractures, which indicate extension of Pluto's crust. Analysis of these stereo images shows that the steep fracture in the upper left of the image is about 1 mile (1.6 kilometers) deep, and the craters in the lower right part of the image are up to 1.3 miles (2.1 km) deep. Smallest visible details are about 0.4 miles (0.6 kilometers) across. You will need 3D glasses to view this image showing an ancient, heavily cratered region of Pluto. http://photojournal.jpl.nasa.gov/catalog/PIA20032

Astrometry of Pluto from 1930-1951 observations: The Lampland plate collection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buie, Marc W.; Folkner, William M., E-mail: buie@boulder.swri.edu, E-mail: william.m.folkner@jpl.nasa.gov

We present a new analysis of 843 photographic plates of Pluto taken by Carl Lampland at Lowell Observatory from 1930–1951. This large collection of plates contains useful astrometric information that improves our knowledge of Pluto's orbit. This improvement provides critical support to the impending flyby of Pluto by New Horizons. New Horizons can do inbound navigation of the system to improve its targeting. This navigation is capable of nearly eliminating the sky-plane errors but can do little to constrain the time of closest approach. Thus the focus on this work was to better determine Pluto's heliocentric distance and to determinemore » the uncertainty on that distance with a particular eye to eliminating systematic errors that might have been previously unrecognized. This work adds 596 new astrometric measurements based on the USNO CCD Astrograph Catalog 4. With the addition of these data the uncertainty of the estimated heliocentric position of Pluto in Developmental Ephemerides 432 (DE432) is at the level of 1000 km. This new analysis gives us more confidence that these estimations are accurate and are sufficient to support a successful flyby of Pluto by New Horizons.« less

Astrometry of Pluto from 1930-1951 Observations: the Lampland Plate Collection

NASA Astrophysics Data System (ADS)

Buie, Marc W.; Folkner, William M.

2015-01-01

We present a new analysis of 843 photographic plates of Pluto taken by Carl Lampland at Lowell Observatory from 1930-1951. This large collection of plates contains useful astrometric information that improves our knowledge of Pluto's orbit. This improvement provides critical support to the impending flyby of Pluto by New Horizons. New Horizons can do inbound navigation of the system to improve its targeting. This navigation is capable of nearly eliminating the sky-plane errors but can do little to constrain the time of closest approach. Thus the focus on this work was to better determine Pluto's heliocentric distance and to determine the uncertainty on that distance with a particular eye to eliminating systematic errors that might have been previously unrecognized. This work adds 596 new astrometric measurements based on the USNO CCD Astrograph Catalog 4. With the addition of these data the uncertainty of the estimated heliocentric position of Pluto in Developmental Ephemerides 432 (DE432) is at the level of 1000 km. This new analysis gives us more confidence that these estimations are accurate and are sufficient to support a successful flyby of Pluto by New Horizons.

Particle Radiation Sources, Propagation and Interactions in Deep Space, at Earth, the Moon, Mars, and Beyond: Examples of Radiation Interactions and Effects

NASA Astrophysics Data System (ADS)

Schwadron, Nathan A.; Cooper, John F.; Desai, Mihir; Downs, Cooper; Gorby, Matt; Jordan, Andrew P.; Joyce, Colin J.; Kozarev, Kamen; Linker, Jon A.; Mikíc, Zoran; Riley, Pete; Spence, Harlan E.; Török, Tibor; Townsend, Lawrence W.; Wilson, Jody K.; Zeitlin, Cary

2017-11-01

Particle radiation has significant effects for astronauts, satellites and planetary bodies throughout the Solar System. Acute space radiation hazards pose risks to human and robotic exploration. This radiation also naturally weathers the exposed surface regolith of the Moon, the two moons of Mars, and other airless bodies, and contributes to chemical evolution of planetary atmospheres at Earth, Mars, Venus, Titan, and Pluto. We provide a select review of recent areas of research covering the origin of SEPs from coronal mass ejections low in the corona, propagation of events through the solar system during the anomalously weak solar cycle 24 and important examples of radiation interactions for Earth, other planets and airless bodies such as the Moon.

Features of the Drag-Free-Simulator demonstrated for the Microscope-mission

NASA Astrophysics Data System (ADS)

List, Meike; Bremer, Stefanie; Dittus, Hansjoerg; Selig, Hanns

The ZARM Drag-Free-Simulator is being developed as a tool for comprehensive mission modeling. Environmental disturbances like solar radiation pressure, atmospheric drag, interactions between the satellite and the Earth's magnetic field can be taken into account via several models. Besides the gravitational field of the Earth, the influence of Sun, Moon and the planets including Pluto can be considered for aimed simulations, too. Methods of modeling and implementation will be presented. At the moment, effort is made to adapt this simulation tool for the french mission MICRO- SCOPE which is designed for testing the equivalence principle up to an accuracy of η=10-15 . Additionally, detailed modeling of on-board capacitive sensors is necessary for a better understanding of the real system. The actual status of mission modeling will be reported.

Panel proposes solar system missions

NASA Astrophysics Data System (ADS)

Showstack, Randy

A proposed probe to the Kuiper Belt and Pluto and another to Europa are among the priority Solar System exploration missions that should be pursued by NASA over the next decade, according to an 11 July report by a steering group of the Space Studies Board of the U.S. National Research Council (NRC).The report, "New Frontiers in the Solar System: An Integrated Exploration Strategy," was requested by NASA, and proposes a set of new missions and facilities to respond to key questions in four cross-cutting themes. The themes, which the report indicates form the basis for an integrated space exploration strategy are: the first billion years of Solar System history; volatiles and organics: the stuff of life; the origin and evolution of habitable worlds; and processes: how planets work.

Pluto's Far Ultraviolet Spectrum and Airglow Emissions

NASA Astrophysics Data System (ADS)

Steffl, A.; Schindhelm, E.; Kammer, J.; Gladstone, R.; Greathouse, T. K.; Parker, J. W.; Strobel, D. F.; Summers, M. E.; Versteeg, M. H.; Ennico Smith, K.; Hinson, D. P.; Linscott, I.; Olkin, C.; Parker, A. H.; Retherford, K. D.; Singer, K. N.; Tsang, C.; Tyler, G. L.; Weaver, H. A., Jr.; Woods, W. W.; Young, L. A.; Stern, A.

2015-12-01

The Alice far ultraviolet spectrograph on the New Horizons spacecraft is the second in a family of six instruments in flight on, or under development for, NASA and ESA missions. Here, we present initial results from the Alice observations of Pluto during the historic flyby. Pluto's far ultraviolet spectrum is dominated by sunlight reflected from the surface with absorption by atmospehric constituents. We tentatively identify C2H2 and C2H4 in Pluto's atmosphere. We also present evidence for weak airglow emissions.

Kuiper Belt Objects Along the Pluto Express Path

NASA Technical Reports Server (NTRS)

Jewitt, David

1999-01-01

The objective of this proposal was to mount a ground-based search for Kuiper Belt objects near the trajectory of the NASA Pluto Express spacecraft. The high density of Kuiper Belt objects established from work on Mauna Kea makes it probable that one or more bodies can be visited by Pluto Express after its encounter with Pluto. The work was funded during its first year through NASA HQ. The second year was funded through Goddard. The third year was never funded.

Developer Initiation and Social Interactions in OSS: A Case Study of the Apache Software Foundation

DTIC Science & Technology

2014-08-01

public interaction with the Apache Pluto community is on the mailing list in August 2006: Hello all, I’am John from the University [...], we are...developing the Prototype for the JSR 286. I hope that we can discuss the code [...] we have made and then develop new code for Pluto together [...], referring...to his and some of his fellow student’s intentions to contribute to Pluto . John gets the attention of Pluto committers and is immediately welcomed as

The Earth Through Time: Implications for Searching for Habitability and Life on Exoplanets

NASA Technical Reports Server (NTRS)

Pilcher, Carl B.

2016-01-01

The Earth has been both a habitable and inhabited planet for around 4 billion years, yet distant observers studying Earth at different epochs in our history would have detected substantially different and probably varying conditions. Understanding Earth's history thus has much to tell us about how to interpret observations of potentially habitable exoplanets. In this talk I will review the history of life on Earth, from the earliest microbial biosphere living under a relatively methane-rich atmosphere to the modern world of animals, plants, and atmospheric oxygen, with a focus on how observable conditions on Earth changed as the planet and its biosphere evolved. I'll discuss the implications of this history for assessing the habitability of-or presence of life on-planets around other stars.

The New Horizons Radio Science Experiment: Expected Performance in Measurements of Pluto's Atmospheric Structure, Surface Pressure, and Surface Temperature

NASA Astrophysics Data System (ADS)

Hinson, D. P.; Linscott, I.; Woods, W. W.; Tyler, G. L.; Bird, M. K.; Paetzold, M.; Strobel, D. F.

2014-12-01

The New Horizons (NH) payload includes a Radio Science Experiment (REX) for investigating key characteristics of Pluto and Charon during the upcoming flyby in July 2015. REX flight equipment augments the NH radio transceiver used for spacecraft communications and tracking. The REX hardware implementation requires 1.6 W and 160 g. This presentation will focus on the final design and the predicted performance of two high-priority observations. First, REX will receive signals from a pair of 70-m antennas on Earth - each transmitting 20 kW at 4.2-cm wavelength - during a diametric radio occultation by Pluto. The data recorded by REX will reveal the surface pressure, the temperature structure of the lower atmosphere, and the surface radius. Second, REX will measure the thermal emission from Pluto at 4.2-cm wavelength during two linear scans across the disk at close range when both the dayside and the nightside are visible, allowing the surface temperature and its spatial variations to be determined. Both scans extend from limb to limb with a resolution of about 10 pixels; one bisects Pluto whereas the second crosses the winter pole. We will illustrate the capabilities of REX by reviewing the method of analysis and the precision achieved in a lunar occultation observed by New Horizons in May 2011. Re-analysis of radio occultation measurements by Voyager 2 at Triton is also under way. More generally, REX objectives include a radio occultation search for Pluto's ionosphere; examination of Charon through both radio occultation and radiometry; a search for a radar echo from Pluto's surface; and improved knowledge of the Pluto system mass and the Pluto-Charon mass ratio from a combination of two-way and one-way Doppler frequency measurements.

(abstract) Student Involvement in the Pluto Mission

NASA Technical Reports Server (NTRS)

Weinstein, Stacy

1994-01-01

The Pluto Fast Flyby mission development baseline consists of 2 identical spacecraft (120 - 165 kg) to be launched to Pluto/ Charon in the late 1990s. These spacecraft are intended to fly by Pluto and Charon in order to perform various remote-sensing scientific investigations and have a mission development cost less than $400M (FY92$) through launch plus 30 days. The Pluto team is committed to involving students in all areas of mission development and operations. In November 1992, the Pluto team sent a request for information to industry and universities looking for ways to lower the mass and cost of the mission. A number of universities responded with creative and promising technological developments. In addition to contracts with industry and other federal labs, contracts were signed with schools which allowed students to apply their research, enabling the Pluto team to use valuable resources on a variety of advanced technology endeavors. Perhaps the most exciting aspect of these investigations was that the deliverables that the students produced were not just final reports, but actual prototype hardware complete with write-ups on lessons learned in machining, programming, and design. Another exciting development was a prototype adapter competition in which 7 universities competed to design, build, and test their idea of a lightweight spacecraft-propulsion stack adapter. Georgia Tech won with an innovative dodecahedron composite lattice cone. Other students from other universities were involved as well. All in all, over 40 students from 20 different colleges made significant contributions to the Pluto Fast Flyby mission development through their efforts. This paper will give an overview of Pluto student involvement, the technologies which they examined, and useful results for the mission.

Mapping the stability region of the 3:2 Neptune-Pluto resonance

NASA Technical Reports Server (NTRS)

Levison, H. F.; Stern, S. A.

1993-01-01

Pluto and Charon are most likely the remnants of a large number of objects that existed in the Uranus-Neptune region at early epochs of the solar system. Numerical integrations have shown that, in general, such objects were ejected from the planetary region on timescales of approximately 10(exp 7) years after Neptune and Uranus reached their current masses. It is thought that the Pluto-Charon system survived to current times without being dynamically removed in this way because it is trapped in a set of secular and mean motion resonances with Neptune. The best-known Pluto-Neptune orbit coupling is the 3:2 mean motion resonance discovered almost 30 years ago by C. Cohen and E. Hubbard. These workers showed that the resonance angle, delta is equivalent to 3(lambda(sub P)) - 2(lambda(sub N)) - omega-bar(sub P) where omega-bar(sub P) is the longitude of perihelion of the Pluto-Charon system, and lambda(sub N) and lambda(sub P) are the mean longitude of Neptune and Pluto-Charon respectively, librates about 180 deg with an amplitude, A(sub delta), of 76 deg. A numerical simulation project to map out the stability region of the 3:2 resonance is reported. The results of these simulations are important to understanding whether Pluto's long-term heliocentric stability requires only the 3:2 resonance, or whether it instead requires one or more of the other Pluto-Neptune resonances. Our study also has another important application. By investigating stability timescales as a function of orbital elements, we gain insight into the fraction of orbital phase space which the stable 3:2 resonance occupies. This fraction is directly related to the probability that the Pluto-Charon system (and possibly other small bodies) could have been captured into this resonance.

The GAPS Programme with HARPS-N at TNG . XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets

NASA Astrophysics Data System (ADS)

Bonomo, A. S.; Desidera, S.; Benatti, S.; Borsa, F.; Crespi, S.; Damasso, M.; Lanza, A. F.; Sozzetti, A.; Lodato, G.; Marzari, F.; Boccato, C.; Claudi, R. U.; Cosentino, R.; Covino, E.; Gratton, R.; Maggio, A.; Micela, G.; Molinari, E.; Pagano, I.; Piotto, G.; Poretti, E.; Smareglia, R.; Affer, L.; Biazzo, K.; Bignamini, A.; Esposito, M.; Giacobbe, P.; Hébrard, G.; Malavolta, L.; Maldonado, J.; Mancini, L.; Martinez Fiorenzano, A.; Masiero, S.; Nascimbeni, V.; Pedani, M.; Rainer, M.; Scandariato, G.

2017-06-01

We carried out a Bayesian homogeneous determination of the orbital parameters of 231 transiting giant planets (TGPs) that are alone or have distant companions; we employed differential evolution Markov chain Monte Carlo methods to analyse radial-velocity (RV) data from the literature and 782 new high-accuracy RVs obtained with the HARPS-N spectrograph for 45 systems over 3 years. Our work yields the largest sample of systems with a transiting giant exoplanet and coherently determined orbital, planetary, and stellar parameters. We found that the orbital parameters of TGPs in non-compact planetary systems are clearly shaped by tides raised by their host stars. Indeed, the most eccentric planets have relatively large orbital separations and/or high mass ratios, as expected from the equilibrium tide theory. This feature would be the outcome of planetary migration from highly eccentric orbits excited by planet-planet scattering, Kozai-Lidov perturbations, or secular chaos. The distribution of α = a/aR, where a and aR are the semi-major axis and the Roche limit, for well-determined circular orbits peaks at 2.5; this agrees with expectations from the high-eccentricity migration (HEM), although it might not be limited to this migration scenario. The few planets of our sample with circular orbits and α> 5 values may have migrated through disc-planet interactions instead of HEM. By comparing circularisation times with stellar ages, we found that hot Jupiters with a< 0.05 au have modified tidal quality factors 105 ≲ Q'p ≲ 109, and that stellar Q's ≳ 106 - 107 are required to explain the presence of eccentric planets at the same orbital distance. As aby-product of our analysis, we detected a non-zero eccentricity e = 0.104-0.018+0.021 for HAT-P-29; we determined that five planets that were previously regarded to be eccentric or to have hints of non-zero eccentricity, namely CoRoT-2b, CoRoT-23b, TrES-3b, HAT-P-23b, and WASP-54b, have circular orbits or undetermined eccentricities; we unveiled curvatures caused by distant companions in the RV time series of HAT-P-2, HAT-P-22, and HAT-P-29; we significantly improved the orbital parameters of the long-period planet HAT-P-17c; and we revised the planetary parameters of CoRoT-1b, which turned out to be considerably more inflated than previously found. Full Tables 1, 2, 5-9 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/602/A107

Surface compositions across Pluto and Charon.

PubMed

Grundy, W M; Binzel, R P; Buratti, B J; Cook, J C; Cruikshank, D P; Dalle Ore, C M; Earle, A M; Ennico, K; Howett, C J A; Lunsford, A W; Olkin, C B; Parker, A H; Philippe, S; Protopapa, S; Quirico, E; Reuter, D C; Schmitt, B; Singer, K N; Verbiscer, A J; Beyer, R A; Buie, M W; Cheng, A F; Jennings, D E; Linscott, I R; Parker, J Wm; Schenk, P M; Spencer, J R; Stansberry, J A; Stern, S A; Throop, H B; Tsang, C C C; Weaver, H A; Weigle, G E; Young, L A

2016-03-18

The New Horizons spacecraft mapped colors and infrared spectra across the encounter hemispheres of Pluto and Charon. The volatile methane, carbon monoxide, and nitrogen ices that dominate Pluto's surface have complicated spatial distributions resulting from sublimation, condensation, and glacial flow acting over seasonal and geological time scales. Pluto's water ice "bedrock" was also mapped, with isolated outcrops occurring in a variety of settings. Pluto's surface exhibits complex regional color diversity associated with its distinct provinces. Charon's color pattern is simpler, dominated by neutral low latitudes and a reddish northern polar region. Charon's near-infrared spectra reveal highly localized areas with strong ammonia absorption tied to small craters with relatively fresh-appearing impact ejecta. Copyright © 2016, American Association for the Advancement of Science.

The Surface Age of Sputnik Planum, Pluto, Must Be Less than 10 Million Years.

PubMed

Trilling, David E

2016-01-01

Data from the New Horizons mission to Pluto show no craters on Sputnik Planum down to the detection limit (2 km for low resolution data, 625 m for high resolution data). The number of small Kuiper Belt Objects that should be impacting Pluto is known to some degree from various astronomical surveys. We combine these geological and telescopic observations to make an order of magnitude estimate that the surface age of Sputnik Planum must be less than 10 million years. This maximum surface age is surprisingly young and implies that this area of Pluto must be undergoing active resurfacing, presumably through some cryo-geophysical process. We discuss three possible resurfacing mechanisms and the implications of each one for Pluto's physical properties.

The PLUTO plastidial nucleobase transporter also transports the thiamin precursor hydroxymethylpyrimidine

PubMed Central

Beaudoin, Guillaume A.W.; Johnson, Timothy S.; Hanson, Andrew D.

2018-01-01

In plants, the hydroxymethylpyrimidine (HMP) and thiazole precursors of thiamin are synthesized and coupled together to form thiamin in plastids. Mutants unable to form HMP can be rescued by exogenous HMP, implying the presence of HMP transporters in the plasma membrane and plastids. Analysis of bacterial genomes revealed a transporter gene that is chromosomally clustered with thiamin biosynthesis and salvage genes. Its closest Arabidopsis homolog, the plastidic nucleobase transporter (PLUTO), is co-expressed with several thiamin biosynthetic enzymes. Heterologous expression of PLUTO in Escherichia coli or Saccharomyces cerevisiae increased sensitivity to a toxic HMP analog, and disrupting PLUTO in an HMP-requiring Arabidopsis line reduced root growth at low HMP concentrations. These data implicate PLUTO in plastidial transport and salvage of HMP. PMID:29507060

Haze heats Pluto's atmosphere yet explains its cold temperature.

PubMed

Zhang, Xi; Strobel, Darrell F; Imanaka, Hiroshi

2017-11-15

Pluto's atmosphere is cold and hazy. Recent observations have shown it to be much colder than predicted theoretically, suggesting an unknown cooling mechanism. Atmospheric gas molecules, particularly water vapour, have been proposed as a coolant; however, because Pluto's thermal structure is expected to be in radiative-conductive equilibrium, the required water vapour would need to be supersaturated by many orders of magnitude under thermodynamic equilibrium conditions. Here we report that atmospheric hazes, rather than gases, can explain Pluto's temperature profile. We find that haze particles have substantially larger solar heating and thermal cooling rates than gas molecules, dominating the atmospheric radiative balance from the ground to an altitude of 700 kilometres, above which heat conduction maintains an isothermal atmosphere. We conclude that Pluto's atmosphere is unique among Solar System planetary atmospheres, as its radiative energy equilibrium is controlled primarily by haze particles instead of gas molecules. We predict that Pluto is therefore several orders of magnitude brighter at mid-infrared wavelengths than previously thought-a brightness that could be detected by future telescopes.

ESO PR Highlights in 2006

NASA Astrophysics Data System (ADS)

2007-01-01

Last year proved to be another exceptional year for the European organisation for ground-based astronomy. ESO should begin the New Year with two new member states: Spain (PR 05/06) and the Czech Republic (PR 52/06). ESO PR Highlights 2006 2006 was a year of renovation and revolution in the world of planets. A new Earth-like exoplanet has been discovered (PR 03/06) using a network of telescopes from all over the world (including the Danish 1.54-m one at ESO La Silla). It is not the only child of this fruitful year: thanks to the combined use of ESO's Very Large Telescope (VLT) and La Silla instruments, a surprising system of twin giant exoplanets was found (PR 29/06), and a trio of Neptune-like planets hosted by a nearby star were identified (PR 18/06). These results open new perspectives on the search for habitable zones and on the understanding of the mechanism of planet formation. The VISIR instrument on the VLT has been providing unique information to answer this last question, by supplying a high resolution view of a planet-forming disc (PR 36/06). There are not only new members in the planets' register: during the General Assembly of the International Astronomical Union held in Prague (Czech Republic), it was decided that Pluto is not a planet anymore but a 'dwarf planet'. Whatever its status, Pluto still has a satellite, Charon, whose radius and density have been measured more accurately by observing a rare occultation from different sites, including Cerro Paranal (PR 02/06). The scientific community dedicated 2006 to the great physicist James Clerk Maxwell (it was the 175th anniversary of the birth): without his electromagnetic theory of light, none of the astonishing discoveries of modern physics could have been achieved. Nowadays we can look at distant galaxies in great detail: the GIRAFFE spectrograph on the VLT revealed that galaxies 6 billion years ago had the same amount of dark matter relative to stars than nowadays (PR 10/06), while SINFONI gave an unprecedented detailed map of a proto-disc galaxy, showing how galaxies looked like 10 billion years ago (PR 31/06). The VLT also helped to discover a large primordial (more than 10 billion years away) 'blob', explained as the early stage formation of a galaxy (PR 23/06). Not only far away galaxies are rich of surprises: also our own Galaxy was the object of investigations during 2006 and its history is now less obscure (PR 34/06 and 41/06). ESO's Very Large Telescope unveiled that the stellar cluster Messier 12 must have lost to our Milky Way galaxy close to one million low-mass stars (PR 04/06). Stealing is not uncommon in astronomy: evidence of stellar vampires - star sucking off material from another - was unearthed in the globular cluster 47 Tucanae (PR 37/06). Still closer to home, the VLT observed Schwassmann-Wachmann 3, a comet that is breaking apart and revealed many mini-comets (PR 15/06). At Paranal, a fourth Auxiliary Telescope was installed for the Very Large Telescope Interferometer (PR 51/06), and since January 2006, not only do natural stars shine: the first artificial star twinkles in the Southern Hemisphere. It does not guide the sailors (it is too faint to be seen by the unaided eye), but it conducts the eye of the present and future telescopes (PR 07/06). And 2006 proved an important year for the future project of ESO, the Extremely Large Telescope. After approval from the ESO council, the European community can now start the final design of this telescope that will without doubt revolutionise astronomy (PR 25/06 and 46/06). ESO PR Photos 2006 2006 was without doubt an explosive year: the explosion of a supernovae of Type Ia in the enchanting Hooked Galaxy was followed from the middle of 2005 for more than a year (PR 22/06) and using observations of 17 supernovae Ia astronomers could make light on the nature of such explosions, that are likely to occur at supersonic speed (PR 44/06). Supernovae are proved to be linked to X-ray flashes (PR 33/06) and to the more energetic gamma-ray bursts. But not all the explosions are associated with supernovae, and a new kind of explosion is indeed suggested by the observation of a new mysterious category of gamma-ray bursts (PR 49/06). The Atacama Pathfinder Experiment (APEX) 12-m sub-millimetre telescope lived up to the ambitions of the scientists by providing access to the 'Cold Universe' with unprecedented sensitivity and image quality. As a demonstration, no less than 26 articles based on early science with APEX were published in a special issue of the research journal Astronomy & Astrophysics (PR 24/06). This year ESO and Chile celebrated ten years of collaboration: a cooperation that led not only to breakthrough discoveries, but also to a growth of astronomy and related sciences in the South American country (PR 21/06). ESO published many images last year as well, including two huge ones, made with the Wide Field Imager: one, made of about 300 million pixels, shows an 'empty field' (PR 14/06), while the other, a 256 million pixel mosaic, depicts in amazing detail the Tarantula Nebula (PR 50/06). These and other images can be accessed through the clickable map, including amazing images of galaxies and of a finally identified flying object (PR 48/06).

Colonizing the Plutoids: The Key to Human Expansion into the Galaxy

NASA Astrophysics Data System (ADS)

Roy, K. I.; Kennedy, R. G.; Fields, D. E.

Pluto-type worlds (plutoids) are far more numerous in our solar system than initially thought with hundreds, maybe thousands, of them existing in the Kuiper belt and Oort cloud. Other stars are likely to also possess many such worlds. These worlds possess almost limitless quantities of water and substantial quantities of nitrogen, which are two limiting ingredients necessary for terraforming planets in the inner solar system. Assuming that faster-than-light travel is impractical, that artificial gravity is only possible via circular motion, that humans remain basically unchanged, and that humanity's expansion into the solar system and beyond is desirable, then exploiting the resources of, and establishing bases and even colonies on, icy plutoids may become essential for human expansion into space. Such colonies face problems involving gravity, radiation, energy supply and complex ecologies. This paper attempts to address those issues and outline what such colonies might look like. This type of colony offers humanity, and perhaps other species, the ability to establish settlements at otherwise undesirable locations, including red and brown dwarf stars. Such colonies could even be established in orphan planets in interstellar space, far from any star.

The New Horizons Radio Science Experiment: Performance and Measurements of Pluto's Atmospheric Structure, Surface Pressure, and Surface Temperature

NASA Astrophysics Data System (ADS)

Linscott, I.; Hinson, D. P.; Bird, M. K.; Stern, A.; Weaver, H. A., Jr.; Olkin, C.; Young, L. A.; Ennico Smith, K.

2015-12-01

The New Horizons (NH) spacecraft payload contained the Radio Science Experiment (REX) for determining key characteristics of Pluto and Charon during the July 14, 2015, flyby of the Pluto/Charon system. The REX flight equipment augments the NH X-band radio transceiver by providing a high precision, narrow band recording of high power uplink transmissions from Earth stations, as well as a record of broadband radiometric power. This presentation will review the performance and initial results of two high- priority observations. First, REX received two pair of 20-kW signals, one pair per polarization, transmitted from the DSN at 4.2-cm wavelength during a diametric radio occultation by Pluto. REX recorded these uplink signals and determined precise measurement of the surface pressure, the temperature structure of the lower atmosphere, and the surface radius of Pluto. The ingress portion of one polarization was played back from the spacecraft in July and processed to obtain the pressure and temperature structure of Pluto's atmosphere. Second, REX measured the thermal emission from Pluto at 4.2- cm wavelength during two linear scans across the disk at close range when both the dayside and the night side are visible. Both scans extend from limb to limb with a resolution of one-tenth Pluto's disk and temperature resolution of 0.1 K. Occultation and radiometric temperature results presented here will encompass additional data scheduled for playback in September.

Mirages and the nature of Pluto's atmosphere

NASA Technical Reports Server (NTRS)

Stansberry, J. A.; Lunine, J. I.; Hubbard, W. B.; Yelle, R. V.; Hunten, D. M.

1994-01-01

We present model occultation lightcurves demonstrating that a strong thermal inversion layer at the base of Pluto's stratosphere can reproduce the minimum flux measured by the Kuiper Airborne Observatory (KAO) during the 1988 occultation of a star by Pluto. The inversion layer also forms the occultation equivalent of a mirage at a radius of 1198 km, which is capable of hiding tropospheres of significant depth. Pluto's surface lies below 1198 km, its radius depending on the depth of the troposphere. We begin by computing plausible temperature structures for Pluto's lower atmosphere, constrained by a calculation of the temperature of the atmosphere near the surface. We then trace rays from the occulted star through the model atmosphere, computing the resultant bending of the ray. Model light curves are obtained by summing the contribution of individual rays within the shadow of Pluto on Earth. We find that we can reproduce the KAO lightcurve using model atmospheres with a temperature inversion and no haze. We have explored models with tropospheres as deep as 40 km (implying a Pluto radius of 1158 km) that reproduce the suite of occultation data. Deeper tropospheres can be fitted to the data, but the mutual event radius of 1150 km probably provides a lower bound. If Pluto has a shallow or nonexistent troposphere, its density is consistent with formation in the solar nebula with modest water loss due to impact ejection. If the troposhere is relatively deep, implying a smaller radius and larger density, significant amounts of water loss are required.

NASA NASA CONNECT: Special World Space Congress. [Videotape].

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Hampton, VA. Langley Research Center.

NASA CONNECT is an annual series of free integrated mathematics, science, and technology instructional distance learning programs for students in grades 5-8. This video presents the World Space Congress 2002, the meeting of the decade for space professionals. Topics discussed range from the discovery of distant planets to medical advancements,…

Exchange of meteorites (and life?) between stellar systems.

PubMed

Melosh, H J

2003-01-01

It is now generally accepted that meteorite-size fragments of rock can be ejected from planetary bodies. Numerical studies of the orbital evolution of such planetary ejecta are consistent with the observed cosmic ray exposure times and infall rates of these meteorites. All of these numerical studies agree that a substantial fraction (up to one-third) of the ejecta from any planet in our Solar System is eventually thrown out of the Solar System during encounters with the giant planets Jupiter and Saturn. In this paper I examine the probability that such interstellar meteorites might be captured into a distant solar system and fall onto a terrestrial planet in that system within a given interval of time. The overall conclusion is that it is very unlikely that even a single meteorite originating on a terrestrial planet in our solar system has fallen onto a terrestrial planet in another stellar system, over the entire period of our Solar System's existence. Although viable microorganisms may be readily exchanged between planets in our solar system through the interplanetary transfer of meteoritic material, it seems that the origin of life on Earth must be sought within the confines of the Solar System, not abroad in the galaxy.

Planet Formation Instrument for the Thirty Meter Telescope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Macintosh, B; Troy, M; Graham, J

2006-02-22

In the closing years of the 20th Century humankind began its exploration of the planetary systems in the solar neighborhood. Precision radial velocity measurements have now yielded the discovery of over 160 planets. Direct imaging of these planets, as opposed to detection of the effects of orbital motion on their parent star, is now feasible, and the first young planet in a wide orbit may have been detected using adaptive optics systems. Gemini and the VLT are building the first generation of high contrast adaptive optics systems, which deliver planet-imaging performance within few Airy rings of the host star. Thesemore » systems will make the first surveys of the outer regions of solar systems by detecting the self-luminous radiation of young planets. These instruments will establish whether Jovian planets form predominantly through 'top-down' (global gravitational instability) or 'bottom-up' (core accretion) processes. The 8-m 'extreme' AO systems cannot see close enough to the host stars to image Doppler planets, and they cannot reach the relatively distant, young clusters and associations where planets are forming. The Planet Formation Instrument will use the nearly four-fold improved angular resolution of TMT to peer into the inner solar systems of Doppler-planet bearing stars to yield a unified sample of planets with known Keplerian orbital elements and atmospheric properties. In star formation regions, where T Tauri stars (young solar type stars) are found in abundance, PFI can see into the snow line, where the icy cores of planets like Jupiter must have formed. Thus, TMT will be the first facility to witness the formation of new planets.« less

Radio emission in Mercury magnetosphere

NASA Astrophysics Data System (ADS)

Varela, J.; Reville, V.; Brun, A. S.; Pantellini, F.; Zarka, P.

2016-10-01

Context. Active stars possess magnetized wind that has a direct impact on planets that can lead to radio emission. Mercury is a good test case to study the effect of the solar wind and interplanetary magnetic field (IMF) on radio emission driven in the planet magnetosphere. Such studies could be used as proxies to characterize the magnetic field topology and intensity of exoplanets. Aims: The aim of this study is to quantify the radio emission in the Hermean magnetosphere. Methods: We use the magnetohydrodynamic code PLUTO in spherical coordinates with an axisymmetric multipolar expansion for the Hermean magnetic field, to analyze the effect of the IMF orientation and intensity, as well as the hydrodynamic parameters of the solar wind (velocity, density and temperature), on the net power dissipated on the Hermean day and night side. We apply the formalism derived by Zarka et al. (2001, Astrophys. Space Sci., 277, 293), Zarka (2007, Planet. Space Sci., 55, 598) to infer the radio emission level from the net dissipated power. We perform a set of simulations with different hydrodynamic parameters of the solar wind, IMF orientations and intensities, that allow us to calculate the dissipated power distribution and infer the existence of radio emission hot spots on the planet day side, and to calculate the integrated radio emission of the Hermean magnetosphere. Results: The obtained radio emission distribution of dissipated power is determined by the IMF orientation (associated with the reconnection regions in the magnetosphere), although the radio emission strength is dependent on the IMF intensity and solar wind hydro parameters. The calculated total radio emission level is in agreement with the one estimated in Zarka et al. (2001, Astrophys. Space Sci., 277, 293) , between 5 × 105 and 2 × 106 W.

Discovery and Classification in Astronomy

NASA Astrophysics Data System (ADS)

Dick, Steven J.

2012-01-01

Three decades after Martin Harwit's pioneering Cosmic Discovery (1981), and following on the recent IAU Symposium "Accelerating the Rate of Astronomical Discovery,” we have revisited the problem of discovery in astronomy, emphasizing new classes of objects. 82 such classes have been identified and analyzed, including 22 in the realm of the planets, 36 in the realm of the stars, and 24 in the realm of the galaxies. We find an extended structure of discovery, consisting of detection, interpretation and understanding, each with its own nuances and a microstructure including conceptual, technological and social roles. This is true with a remarkable degree of consistency over the last 400 years of telescopic astronomy, ranging from Galileo's discovery of satellites, planetary rings and star clusters, to the discovery of quasars and pulsars. Telescopes have served as "engines of discovery” in several ways, ranging from telescope size and sensitivity (planetary nebulae and spiral galaxies), to specialized detectors (TNOs) and the opening of the electromagnetic spectrum for astronomy (pulsars, pulsar planets, and most active galaxies). A few classes (radiation belts, the solar wind and cosmic rays), were initially discovered without the telescope. Classification also plays an important role in discovery. While it might seem that classification marks the end of discovery, or a post-discovery phase, in fact it often marks the beginning, even a pre-discovery phase. Nowhere is this more clearly seen than in the classification of stellar spectra, long before dwarfs, giants and supergiants were known, or their evolutionary sequence recognized. Classification may also be part of a post-discovery phase, as in the MK system of stellar classification, constructed after the discovery of stellar luminosity classes. Some classes are declared rather than discovered, as in the case of gas and ice giant planets, and, infamously, Pluto as a dwarf planet.

Biosignatures of Exoplanets

NASA Technical Reports Server (NTRS)

Kiang, Nancy Y.

2017-01-01

There was a time during Western civilization when musing about worlds other than Earth could be life-threatening. In 1600 Giordano Bruno was burnt at the stake as a heretic for claiming, amongst other things, that the fixed stars were in fact suns with planets moving around them, and furthermore, that lifeforms similar to those on Earth might exist on these planets. Although these ideas were not the result of scientific observation but rather of philosophical reflexions, Giordano Bruno is today recognized as the father of the idea of exoplanets. The study of planets revolving around distant stars has become one of the most thrilling disciplines in astronomy. As it did 400 years ago, this subject touches on the most profound questions of mankind, including the uniqueness of the planet Earth and even our own uniqueness as an intelligent species. As always in astronomy distance is an issue. While it requires a lot of patience to reach the planets within our own solar system, direct visits to exoplanets will not be feasible in the foreseeable future. Is there an alternative approach to find a second Earth?

DISK AROUND STAR MAY BE WARPED BY UNSEEN PLANET

NASA Technical Reports Server (NTRS)

2002-01-01

NASA's Hubble Space Telescope has provided strong evidence for the existence of a roughly Jupiter-sized planet orbiting the star Beta Pictoris. Detailed Hubble images of the inner region of the 200-billion mile diameter dust disk encircling the star reveal an unexpected warp. Researchers say the warp can be best explained as caused by the gravitational pull of an unseen planet. The suspected planet would dwell within a five-billion mile wide clear zone in the center of the disk. This zone has long been suspected of harboring planets that swept it clear of debris, but the Hubble discovery provides more definitive evidence that a planet is there. (Alternative theories suggest the clear zone is empty because it is too warm for ice particles to exist.) 'We were surprised to find that the innermost region of the disk is orbiting in a different plane from the rest of the disk,' says Chris Burrows (Space Telescope Science Institute, Baltimore, Maryland, and the European Space Agency) who is presenting his results at the meeting of the American Astronomical Society in San Antonio, Texas. As he analyzed Hubble images, taken in January 1995 with the Wide Field Planetary Camera 2, Burrows discovered an unusual bulge in the nearly edge-on disk, which was mirrored on the other side of the star. 'Such a warp cannot last for very long,' says Burrows. 'This means that something is still twisting the disk and keeping out of a basic flat shape.' 'The presence of the warp is strong though indirect evidence for the existence of planets in this system. If Beta Pictoris had a solar system like ours, it would produce a warp like the one we see.' Burrows concludes, 'The Beta Pictoris system seems to contain at least one planet not too dissimilar from Jupiter in size and orbit. Rocky planets like Earth might circle Beta Pictoris as well. However, there is no evidence for these yet. Any planet will be at least a billion- times fainter than the star, and presently impossible to view directly, even with Hubble.' An alterative explanation of the warp is that the disk could have been perturbed by a passing star However this is very unlikely because only the inner region of the disk is affected. Burrows estimates that there is a one in 400,000 chance for Beta Pictoris to have such a close encounter with another star. 'Though Beta Pictoris is probably at least 100 million years old, other explanations for the warp do not allow it to last for very long.' The size of the warp allows Burrows to roughly measure the mass of the orbiting body. 'It must lie well within the warp, probably within the clear zone that exists around Beta Pictoris.' On the other hand, he points out, it cannot be too close to the star because its gravitational pull would cause the star to 'jiggle,' and such radial velocity variations have never been seen in Beta Pictoris. Burrows estimates the planet is from one-twentieth to twenty times the mass of Jupiter. The planet must lie within the range of distances typical of planetary distances within our solar system -- from about Earth's distance from the Sun to about Pluto's distance from the Sun (Pluto is roughly 30 times father from the Sun than Earth.) If the suspected planet were as far from Beta Pictoris as Jupiter is from our Sun, it also would have about the same mass as Jupiter. The planet's orbit must be inclined by about three degrees to the plane of the Beta Pictoris disk, and this is typical of the inclinations of the orbits of the planets in our solar system. The star is located 50 light-years away in the southern constellation Pictor (Painter's Easel). Though its precise age is not known, Beta Pictoris is generally considered a mature, main sequence star, slightly hotter than our Sun. Detections of substellar objects orbiting nearby stars have recently been reported for two other normal (i.e., main sequence) stars -- Gliese 229 and 51 Pegasus. However, Beta Pictoris is the only candidate that looks like it might possess a planetary system similar to our own. Beta Pictoris also is the only known star with a circumstellar disk of gas and dust that can be optically imaged. Despite the presence of dust around approximately one-third of the brightest nearby stars -- as deduced from NASA's Infrared Astronomy Satellite (IRAS) data -- ground-based telescope imaging has not detected other disks. Several Hubble programs are currently in progress to search for these disks. The NICMOS (Near Infrared Camera and Multi-Object Spectrometer), to be installed on Hubble during the February 1997 servicing mission, will provide a near-infrared capability needed for this type of search. * * * * * The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).

A giant impact origin of Pluto-Charon.

PubMed

Canup, Robin M

2005-01-28

Pluto and its moon, Charon, are the most prominent members of the Kuiper belt, and their existence holds clues to outer solar system formation processes. Here, hydrodynamic simulations are used to demonstrate that the formation of Pluto-Charon by means of a large collision is quite plausible. I show that such an impact probably produced an intact Charon, although it is possible that a disk of material orbited Pluto from which Charon later accumulated. These findings suggest that collisions between 1000-kilometer-class objects occurred in the early inner Kuiper belt.

Kuiper Belt Objects Along the Pluto Express Path

NASA Technical Reports Server (NTRS)

Jewitt, David C.

1998-01-01

The science objective of this work was to identify objects in the Kuiper Belt which will, in the 5 years following Pluto encounter, be close to the flight path of NASA's Pluto-Kuiper Express. Currently, launch is scheduled for 2004 with a flight time of about 1 decade. Early identification of post-Pluto targets is important for mission design and orbit refinement. An object or objects close enough to the flight path can be visited and studied at high resolution, using only residual gas in the thrusters to affect a close encounter.

Hemispherical Pluto and Charon Color Composition From New Horizons

NASA Technical Reports Server (NTRS)

Ennico, K.; Parker, A.; Howett, C. A. J.; Olkin, C. B.; Spencer, J. R.; Grundy, W. M.; Reuter, D. E.; Cruikshank, D. P.; Binzel, R. P.; Buie, M. W.;

New Horizons at Pluto

NASA Technical Reports Server (NTRS)

2007-01-01

Artist's concept of the New Horizons spacecraft as it approaches Pluto and its largest moon, Charon, in July 2015. The craft's miniature cameras, radio science experiment, ultraviolet and infrared spectrometers and space plasma experiments will characterize the global geology and geomorphology of Pluto and Charon, map their surface compositions and temperatures, and examine Pluto's atmosphere in detail. The spacecraft's most prominent design feature is a nearly 7-foot (2.1-meter) dish antenna, through which it will communicate with Earth from as far as 4.7 billion miles (7.5 billion kilometers) away.

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

An audience member asks the panelists a question at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. Scientists discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

On the origin of Triton and Pluto

NASA Technical Reports Server (NTRS)

Mckinnon, W. B.

1984-01-01

Lyttleton's (1936) hypothesis that Triton and Pluto originated as adjacent prograde satellites of Neptune is evaluated, and it is shown that with the presently accepted masses of Triton and Pluto-Charon, the momentum and energy exchange required to set Triton on a retrograde orbit is impossible. The Pluto-Charon system could not have acquired its present angular momentum state during an ejection event unless a physical collision was involved, which is quite unlikely. The simplest hypothesis is that Triton and Pluto are independent representatives of large outer solar system planetesimals. Triton is simply captured, with spectacular consequences that include runaway melting of interior ices and release to the surface of clathrated CH4, CO, and N2. Condensed remnants of this protoatmosphere could account for features in Triton's unique spectrum.

On the Origin of Triton and Pluto

NASA Technical Reports Server (NTRS)

Mckinnon, W. B.

1985-01-01

Lyttleton's (1936) hypothesis that Triton and Pluto originated as adjacent prograde satellites of Neptune is evaluated, and it is shown that with the presently accepted masses of Triton and Pluto-Charon, the momentum and energy exchange required to sell Triton on a retrograde orbit is impossible. The Pluto-Charon system could not have acquired its present angular momentum state during an ejection event unless a physical collision was involved, which is quite unlikely. The simplest hypothesis is that Triton and Pluto are independent representatives of large outer solar system planetesimals. Triton is simply captured, with spectacular consequences that include runaway melting of interior ices and release to the surface of clathrated CH4, CO, and N2. Condensed remnants of this protoatmosphere could account for features in Triton's unique spectrum.

The PLUTO plastidial nucleobase transporter also transports the thiamin precursor hydroxymethylpyrimidine.

PubMed

Beaudoin, Guillaume A W; Johnson, Timothy S; Hanson, Andrew D

2018-04-27

In plants, the hydroxymethylpyrimidine (HMP) and thiazole precursors of thiamin are synthesized and coupled together to form thiamin in plastids. Mutants unable to form HMP can be rescued by exogenous HMP, implying the presence of HMP transporters in the plasma membrane and plastids. Analysis of bacterial genomes revealed a transporter gene that is chromosomally clustered with thiamin biosynthesis and salvage genes. Its closest Arabidopsis homolog, the plastidic nucleobase transporter (PLUTO), is co-expressed with several thiamin biosynthetic enzymes. Heterologous expression of PLUTO in Escherichia coli or Saccharomyces cerevisiae increased sensitivity to a toxic HMP analog, and disrupting PLUTO in an HMP-requiring Arabidopsis line reduced root growth at low HMP concentrations. These data implicate PLUTO in plastidial transport and salvage of HMP. © 2018 The Author(s).

FIRST ULTRAVIOLET REFLECTANCE SPECTRA OF PLUTO AND CHARON BY THE HUBBLE SPACE TELESCOPE COSMIC ORIGINS SPECTROGRAPH: DETECTION OF ABSORPTION FEATURES AND EVIDENCE FOR TEMPORAL CHANGE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stern, S. A.; Spencer, J. R.; Shinn, A.

We have observed the mid-UV spectra of both Pluto and its large satellite, Charon, at two rotational epochs using the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) in 2010. These are the first HST/COS measurements of Pluto and Charon. Here we describe the observations and our reduction of them, and present the albedo spectra, average mid-UV albedos, and albedo slopes we derive from these data. These data reveal evidence for a strong absorption feature in the mid-UV spectrum of Pluto; evidence for temporal change in Pluto's spectrum since the 1990s is reported, and indirect evidence for a near-UV spectralmore » absorption on Charon is also reported.« less

The subsurface of Pluto from submillimetre observations

NASA Astrophysics Data System (ADS)

Greaves, J. S.; Whitelaw, A. C. M.; Bendo, G. J.

2015-04-01

Surface areas on Pluto change in brightness and colour, at optical to infrared wavelengths, over time-scales as short as years. The subsurface contains a reservoir of frozen volatiles, but little is known about it because Pluto is out of reach for cm-radar. Here we present a 0.85 mm wavelength light curve of the Pluto system, from archival data taken in 1997 August with the SCUBA (Submillimetre Common-User Bolometer Array) camera on the James Clerk Maxwell Telescope (JCMT). This wavelength probes for the first time to just below the skin depth of thermal changes over Pluto's day. The light curve differs significantly from counterparts in the mid- to far-infrared, in a longitude range that is optically dark on Pluto's surface. An estimate from Herschel of the 0.5 mm flux in 2012 is comparable to the mean 0.45 mm flux from SCUBA in 1997, suggesting that layers centimetres below the surface have not undergone any gross temperature change. The longitudes that are relatively submillimetre-faint could have a different emissivity, perhaps with a subsurface layer richer in nitrogen or methane ices than at the surface. The Radio Science Experiment (REX) instrument on New Horizons may be able to constrain physical properties deeper down, as it looks back on Pluto's nightside after the 2015 July flyby.

Determination of the System Mass and the Individual Masses of Pluto and Charon from New Horizons Radio Tracking

NASA Astrophysics Data System (ADS)

Hahn, M.; Paetzold, M.; Andert, T.; Bird, M. K.; Tyler, G. L.; Hinson, D. P.; Linscott, I.; Stern, A.; Weaver, H. A., Jr.; Young, L. A.; Ennico Smith, K.; Olkin, C.

2016-12-01

One objective of the New Horizons Radio Science Experiment REX is the direct determination of the system mass and the individual masses of Pluto and Charon. About four weeks of two-way radio tracking centered around the closest approach of New Horizons to the Pluto system were processed. Major problems during the processing were the changes in spacecraft attitude by thrusters which applied extra Δv to the spacecraft motion masking partially the continuously perturbed motion caused by the attracting forces of the Pluto system members. The times of the spacecraft thruster activity are known but the applied Δv magnitude needed to be specifically adjusted. No two-way tracking was available during the flyby day on 14th July but slots of the REX one-way uplink observations cover the most important time near closest approach, these are for example the Pluto and Charon Earth occultation entries and exits. The REX data during the flyby day allowed to extract the individual masses of Pluto and Charon from the system mass at high precision. The relative errors of the mass determinations are below 0.02% and 0.2%, respectively. The masses of the 4 small satellites in the Pluto system could not be resolved.

Where is the Geophysical Evidence for the Giant Impact Origin of the Pluto System?

NASA Astrophysics Data System (ADS)

McKinnon, W. B.; Singer, K. N.; Nimmo, F.; Spencer, J. R.; Young, L. A.; Weaver, H. A., Jr.; Stern, S. A.

2016-12-01

Prior to the New Horizons flyby of the Pluto system, it was anticipated that both Pluto and Charon might show geological or geophysical evidence of the giant impact thought responsible for the formation of Charon and the smaller satellites. Although dynamical and compositional evidence still supports the giant impact model (McKinnon et al., submitted to Icarus), the question remains as to whether the geology of Pluto or Charon records evidence of this cataclysm. The collision speed and energy were most likely not large enough to melt all the ices in the precursor bodies, so surviving geological evidence is not out of the question. Specifically, Pluto post-impact should have been rapidly rotating (with a period as short as 5-6 hr) and highly distorted; Charon under most circumstances would have rapidly despun but have been a highly distorted triaxial body. The tidal evolution end state for both is close to spherical, but fossil figures were anticipated, which in addition to providing direct evidence for post-impact tidal evolution, would provide important clues to thermal and structural evolution. For Pluto, McKinnon and Singer (DPS 2014, abs. 419.07) predicted a flattening >1% (radii differences >10 km) for a strengthless icy lithosphere and an unrelaxed rock core. For a fully relaxed core, they predicted a >2-3 km fossil bulge supported by icy lithospheric strength (corresponding to a minimum past lithosphere thickness of 50 km). New Horizons image analyses have limited any oblateness for Pluto to 0.6% (Nimmo et al., Icarus, in press), which corresponds to <7 km flattening. So Pluto may yet possess a geophysically meaningful oblateness, only one not yet directly detectable (moreover, in order to be consistent with the observations, Pluto's rock core either completed its formation post-spindown, or was too weak to support much non-hydrostatic topography). Such an equator-to-pole surface elevation difference, even a subtle one, could express itself through control of Pluto's zonal albedo pattern (i.e., dark, reddish Cthulhu Regio, Krun and other Macula are all equatorial [names are informal]). Even for a completely relaxed shape, the tectonic effects on Pluto's surface should be manifest. There is a rich variety of tectonic expression, but no obvious match to classic predicted tectonic despinning patterns.

Detailed Astrometric Analysis of Pluto

NASA Astrophysics Data System (ADS)

ROSSI, GUSTAVO B.; Vieira-Martins, R.; Camargo, J. I.; Assafin, M.

2013-05-01

Abstract (2,250 Maximum Characters): Pluto is the main representant of the transneptunian objects (TNO's), presenting some peculiarities such as an atmosphere and a satellite system with 5 known moons: Charon, discovered in 1978, Nix and Hydra, in 2006, P4 in 2011 and P5 in 2012. Until the arrival of the New Horizons spacecraft to this system (july 2015), stellar occultations are the most efficient method, from the ground, to know physical and dinamical properties of this system. In 2010, it was evident a drift in declinations (about 20 mas/year) comparing to the ephemerides. This fact motivated us to remake the reductions and analysis of a great set of our observations at OPD/LNA, in a total of 15 years. The ephemerides and occultations results was then compared with the astrometric and photometric reductions of CCD images of Pluto (around 6500 images). Two corrections were used for a refinement of the data set: diferential chromatic refraction and photocenter. The first is due to the mean color of background stars beeing redder than the color of Pluto, resulting in a slightly different path of light through the atmosphere (that may cause a difference in position of 0.1”). It became more evident because Pluto is crossing the region of the galactic plane. The photocenter correction is based on two gaussians curves overlapped, with different hights and non-coincident centers, corresponding to Pluto and Charon (since they have less than 1” of angular separation). The objective is to separate these two gaussian curves from the observed one and find the right position of Pluto. The method is strongly dependent of the hight of each of the gaussian curves, related to the respective albedos of charon and Pluto. A detailed analysis of the astrometric results, as well a comparison with occultation results was made. Since Pluto has an orbital period of 248,9 years and our interval of observation is about 15 years, we have around 12% of its observed orbit and also, our observations were made when Pluto was near its periapsis. With the corrections made, the ephemeris, when recalculated, shall not present sistematic drifts near the temporal interval in wich contains our observational data, allowing the determination of local adjustments at the Pluto orbit.

A General Framework for Discovery and Classification in Astronomy

NASA Astrophysics Data System (ADS)

Dick, Steven J.

2012-09-01

An analysis of the discovery of 82 classes of astronomical objects reveals an extended structure of discovery, consisting of detection, interpretation and understanding, each with its own nuances and a microstructure including conceptual, technological and social roles. This is true with a remarkable degree of consistency over the last 400 years of telescopic astronomy, ranging from Galileo's discovery of satellites, planetary rings and star clusters, to the discovery of quasars and pulsars. Telescopes have served as ``engines of discovery'' in several ways, ranging from telescope size and sensitivity (planetary nebulae and spiral nebulae), to specialized detectors (TNOs) and the opening of the electromagnetic spectrum for astronomy (pulsars, pulsar planets, and most active galaxies). A few classes (radiation belts, the solar wind and cosmic rays) were initially discovered without the telescope. Classification also plays an important role in discovery. While it might seem that classification marks the end of discovery, or a post-discovery phase, in fact it often marks the beginning, even a pre-discovery phase. Nowhere is this more clearly seen than in the classification of stellar spectra, long before dwarfs, giants and supergiants were known, or their evolutionary sequence recognized. Classification may also be part of a post-discovery phase, as in the MK system of stellar classification, constructed after the discovery of stellar luminosity classes. Some classes are declared rather than detected, as in the case of gas and ice giant planets, and, infamously, Pluto as a dwarf planet. Others are inferred rather than detected, including most classes of stars.

Clyde W. Tombaugh, Discoverer of Pluto: A Personal Retrospective

NASA Astrophysics Data System (ADS)

Levy, David H.

2013-10-01

This talk offers a retrospective of the life, times, and ideas of Clyde W. Tombaugh. One of the premier observers of the twentieth century, Tombaugh began observing as a teenager and was hired by the Lowell Observatory in Flagstaff, Arizona, in 1928, to resume and conduct the searh for “Planet X”, the world postulated by Percival Lowell, founder of the observatory. Tombaugh discovered this object on February 18, 1930, and it was subsequently named Pluto a few months later. Tombaugh’s life following the discovery was busy, full, and sometimes difficult. He continued his search for about fifteen years, discovering five open clusters, one globular cluster, a new cataclysmic variable star, and likely the first known supercluster of galaxies. He also discovered a comet, but that find was not confirmed for 81 years until it was rediscovered by the Tenagra Observatories just a few months ago and named Comet Tombaugh-Tenagra. Tombaugh was as well known for his delightful sense of humor and fun as he was for his abilities as an observer. However it would be difficult to present such a talk without some mention of the concern and depression he endured at the end of his life about the changing status of his signature discovery. Ultimately, this presentation will try to offer a personal perspective of the man and the scientist I knew for the decades since I first heard him speak in 1963 until his death in 1997.

Haze production rates in super-Earth and mini-Neptune atmosphere experiments

NASA Astrophysics Data System (ADS)

Hörst, Sarah M.; He, Chao; Lewis, Nikole K.; Kempton, Eliza M.-R.; Marley, Mark S.; Morley, Caroline V.; Moses, Julianne I.; Valenti, Jeff A.; Vuitton, Véronique

2018-04-01

Numerous Solar System atmospheres possess photochemically generated hazes, including the characteristic organic hazes of Titan and Pluto. Haze particles substantially impact atmospheric temperature structures and may provide organic material to the surface of a world, potentially affecting its habitability. Observations of exoplanet atmospheres suggest the presence of aerosols, especially in cooler (<800 K), smaller (<0.3× Jupiter's mass) exoplanets. It remains unclear whether the aerosols muting the spectroscopic features of exoplanet atmospheres are condensate clouds or photochemical hazes1-3, which is difficult to predict from theory alone4. Here, we present laboratory haze simulation experiments that probe a broad range of atmospheric parameters relevant to super-Earth- and mini-Neptune-type planets5, the most frequently occurring type of planet in our galaxy6. It is expected that photochemical haze will play a much greater role in the atmospheres of planets with average temperatures below 1,000 K (ref. 7), especially those planets that may have enhanced atmospheric metallicity and/or enhanced C/O ratios, such as super-Earths and Neptune-mass planets8-12. We explored temperatures from 300 to 600 K and a range of atmospheric metallicities (100×, 1,000× and 10,000× solar). All simulated atmospheres produced particles, and the cooler (300 and 400 K) 1,000× solar metallicity (`H2O-dominated' and CH4-rich) experiments exhibited haze production rates higher than our standard Titan simulation ( 10 mg h-1 versus 7.4 mg h-1 for Titan13). However, the particle production rates varied greatly, with measured rates as low as 0.04 mg h-1 (for the case with 100× solar metallicity at 600 K). Here, we show that we should expect great diversity in haze production rates, as some—but not all—super-Earth and mini-Neptune atmospheres will possess photochemically generated haze.

Haze production rates in super-Earth and mini-Neptune atmosphere experiments

NASA Astrophysics Data System (ADS)

Hörst, Sarah M.; He, Chao; Lewis, Nikole K.; Kempton, Eliza M.-R.; Marley, Mark S.; Morley, Caroline V.; Moses, Julianne I.; Valenti, Jeff A.; Vuitton, Véronique

2018-03-01

Numerous Solar System atmospheres possess photochemically generated hazes, including the characteristic organic hazes of Titan and Pluto. Haze particles substantially impact atmospheric temperature structures and may provide organic material to the surface of a world, potentially affecting its habitability. Observations of exoplanet atmospheres suggest the presence of aerosols, especially in cooler (<800 K), smaller (<0.3× Jupiter's mass) exoplanets. It remains unclear whether the aerosols muting the spectroscopic features of exoplanet atmospheres are condensate clouds or photochemical hazes1-3, which is difficult to predict from theory alone4. Here, we present laboratory haze simulation experiments that probe a broad range of atmospheric parameters relevant to super-Earth- and mini-Neptune-type planets5, the most frequently occurring type of planet in our galaxy6. It is expected that photochemical haze will play a much greater role in the atmospheres of planets with average temperatures below 1,000 K (ref. 7), especially those planets that may have enhanced atmospheric metallicity and/or enhanced C/O ratios, such as super-Earths and Neptune-mass planets8-12. We explored temperatures from 300 to 600 K and a range of atmospheric metallicities (100×, 1,000× and 10,000× solar). All simulated atmospheres produced particles, and the cooler (300 and 400 K) 1,000× solar metallicity (`H2O-dominated' and CH4-rich) experiments exhibited haze production rates higher than our standard Titan simulation ( 10 mg h-1 versus 7.4 mg h-1 for Titan13). However, the particle production rates varied greatly, with measured rates as low as 0.04 mg h-1 (for the case with 100× solar metallicity at 600 K). Here, we show that we should expect great diversity in haze production rates, as some—but not all—super-Earth and mini-Neptune atmospheres will possess photochemically generated haze.

Planet Formation in Disks with Inclined Binary Companions: Can Primordial Spin-Orbit Misalignment be Produced?

NASA Astrophysics Data System (ADS)

Zanazzi, J. J.; Lai, Dong

2018-04-01

Many hot Jupiter (HJ) systems have been observed to have their stellar spin axis misaligned with the planet's orbital angular momentum axis. The origin of this spin-orbit misalignment and the formation mechanism of HJs remain poorly understood. A number of recent works have suggested that gravitational interactions between host stars, protoplanetary disks, and inclined binary companions may tilt the stellar spin axis with respect to the disk's angular angular momentum axis, producing planetary systems with misaligned orbits. These previous works considered idealized disk evolution models and neglected the gravitational influence of newly formed planets. In this paper, we explore how disk photoevaporation and planet formation and migration affect the inclination evolution of planet-star-disk-binary systems. We take into account planet-disk interactions and the gravitational spin-orbit coupling between the host star and the planet. We find that the rapid depletion of the inner disk via photoevaporation reduces the excitation of stellar obliquities. Depending on the formation and migration history of HJs, the spin-orbit coupling between the star and the planet may reduces and even completely suppress the excitation of stellar obliquities. Our work constrains the formation/migration history of HJs. On the other hand, planetary systems with "cold" Jupiters or close-in super-earths may experience excitation of stellar obliquities in the presence of distant inclined companions.

Planet formation in discs with inclined binary companions: can primordial spin-orbit misalignment be produced?

NASA Astrophysics Data System (ADS)

Zanazzi, J. J.; Lai, Dong

2018-07-01

Many hot Jupiter (HJ) systems have been observed to have their stellar spin axis misaligned with the planet's orbital angular momentum axis. The origin of this spin-orbit misalignment and the formation mechanism of HJs remain poorly understood. A number of recent works have suggested that gravitational interactions between host stars, protoplanetary discs, and inclined binary companions may tilt the stellar spin axis with respect to the disc's angular angular momentum axis, producing planetary systems with misaligned orbits. These previous works considered idealized disc evolution models and neglected the gravitational influence of newly formed planets. In this paper, we explore how disc photoevaporation and planet formation and migration affect the inclination evolution of planet-star-disc-binary systems. We take into account planet-disc interactions and the gravitational spin-orbit coupling between the host star and the planet. We find that the rapid depletion of the inner disc via photoevaporation reduces the excitation of stellar obliquities. Depending on the formation and migration history of HJs, the spin-orbit coupling between the star and the planet may reduces and even completely suppress the excitation of stellar obliquities. Our work constrains the formation/migration history of HJs. On the other hand, planetary systems with `cold' Jupiters or close-in super-earths may experience excitation of stellar obliquities in the presence of distant inclined companions.

The rapid formation of Sputnik Planitia early in Pluto's history.

PubMed

Hamilton, Douglas P; Stern, S A; Moore, J M; Young, L A

2016-11-30

Pluto's Sputnik Planitia is a bright, roughly circular feature that resembles a polar ice cap. It is approximately 1,000 kilometres across and is centred on a latitude of 25 degrees north and a longitude of 175 degrees, almost directly opposite the side of Pluto that always faces Charon as a result of tidal locking. One explanation for its location includes the formation of a basin in a giant impact, with subsequent upwelling of a dense interior ocean. Once the basin was established, ice would naturally have accumulated there. Then, provided that the basin was a positive gravity anomaly (with or without the ocean), true polar wander could have moved the feature towards the Pluto-Charon tidal axis, on the far side of Pluto from Charon. Here we report modelling that shows that ice quickly accumulates on Pluto near latitudes of 30 degrees north and south, even in the absence of a basin, because, averaged over its orbital period, those are Pluto's coldest regions. Within a million years of Charon's formation, ice deposits on Pluto concentrate into a single cap centred near a latitude of 30 degrees, owing to the runaway albedo effect. This accumulation of ice causes a positive gravity signature that locks, as Pluto's rotation slows, to a longitude directly opposite Charon. Once locked, Charon raises a permanent tidal bulge on Pluto, which greatly enhances the gravity signature of the ice cap. Meanwhile, the weight of the ice in Sputnik Planitia causes the crust under it to slump, creating its own basin (as has happened on Earth in Greenland). Even if the feature is now a modest negative gravity anomaly, it remains locked in place because of the permanent tidal bulge raised by Charon. Any movement of the feature away from 30 degrees latitude is countered by the preferential recondensation of ices near the coldest extremities of the cap. Therefore, our modelling suggests that Sputnik Planitia formed shortly after Charon did and has been stable, albeit gradually losing volume, over the age of the Solar System.

The rapid formation of Sputnik Planitia early in Pluto's history

NASA Astrophysics Data System (ADS)

Hamilton, Douglas P.; Stern, S. A.; Moore, J. M.; Young, L. A.; Binzel, R. P.; Buie, M. W.; Buratti, B. J.; Cheng, A. F.; Ennico, K.; Grundy, W. M.; Linscott, I. R.; McKinnon, W. B.; Olkin, C. B.; Reitsema, H. J.; Reuter, D. C.; Schenk, P.; Showalter, M. R.; Spencer, J. R.; Tyler, G. L.; Weaver, H. A.

2016-12-01

Pluto's Sputnik Planitia is a bright, roughly circular feature that resembles a polar ice cap. It is approximately 1,000 kilometres across and is centred on a latitude of 25 degrees north and a longitude of 175 degrees, almost directly opposite the side of Pluto that always faces Charon as a result of tidal locking. One explanation for its location includes the formation of a basin in a giant impact, with subsequent upwelling of a dense interior ocean. Once the basin was established, ice would naturally have accumulated there. Then, provided that the basin was a positive gravity anomaly (with or without the ocean), true polar wander could have moved the feature towards the Pluto-Charon tidal axis, on the far side of Pluto from Charon. Here we report modelling that shows that ice quickly accumulates on Pluto near latitudes of 30 degrees north and south, even in the absence of a basin, because, averaged over its orbital period, those are Pluto's coldest regions. Within a million years of Charon's formation, ice deposits on Pluto concentrate into a single cap centred near a latitude of 30 degrees, owing to the runaway albedo effect. This accumulation of ice causes a positive gravity signature that locks, as Pluto's rotation slows, to a longitude directly opposite Charon. Once locked, Charon raises a permanent tidal bulge on Pluto, which greatly enhances the gravity signature of the ice cap. Meanwhile, the weight of the ice in Sputnik Planitia causes the crust under it to slump, creating its own basin (as has happened on Earth in Greenland). Even if the feature is now a modest negative gravity anomaly, it remains locked in place because of the permanent tidal bulge raised by Charon. Any movement of the feature away from 30 degrees latitude is countered by the preferential recondensation of ices near the coldest extremities of the cap. Therefore, our modelling suggests that Sputnik Planitia formed shortly after Charon did and has been stable, albeit gradually losing volume, over the age of the Solar System.

Structure-Function Relationship of a Plant NCS1 Member – Homology Modeling and Mutagenesis Identified Residues Critical for Substrate Specificity of PLUTO, a Nucleobase Transporter from Arabidopsis

PubMed Central

Witz, Sandra; Panwar, Pankaj; Schober, Markus; Deppe, Johannes; Pasha, Farhan Ahmad; Lemieux, M. Joanne; Möhlmann, Torsten

2014-01-01

Plastidic uracil salvage is essential for plant growth and development. So far, PLUTO, the plastidic nucleobase transporter from Arabidopsis thaliana is the only known uracil importer at the inner plastidic membrane which represents the permeability barrier of this organelle. We present the first homology model of PLUTO, the sole plant NCS1 member from Arabidopsis based on the crystal structure of the benzyl hydantoin transporter MHP1 from Microbacterium liquefaciens and validated by molecular dynamics simulations. Polar side chains of residues Glu-227 and backbones of Val-145, Gly-147 and Thr-425 are proposed to form the binding site for the three PLUTO substrates uracil, adenine and guanine. Mutational analysis and competition studies identified Glu-227 as an important residue for uracil and to a lesser extent for guanine transport. A differential response in substrate transport was apparent with PLUTO double mutants E227Q G147Q and E227Q T425A, both of which most strongly affected adenine transport, and in V145A G147Q, which markedly affected guanine transport. These differences could be explained by docking studies, showing that uracil and guanine exhibit a similar binding mode whereas adenine binds deep into the catalytic pocket of PLUTO. Furthermore, competition studies confirmed these results. The present study defines the molecular determinants for PLUTO substrate binding and demonstrates key differences in structure-function relations between PLUTO and other NCS1 family members. PMID:24621654

Structure-function relationship of a plant NCS1 member--homology modeling and mutagenesis identified residues critical for substrate specificity of PLUTO, a nucleobase transporter from Arabidopsis.

PubMed

Witz, Sandra; Panwar, Pankaj; Schober, Markus; Deppe, Johannes; Pasha, Farhan Ahmad; Lemieux, M Joanne; Möhlmann, Torsten

2014-01-01

Plastidic uracil salvage is essential for plant growth and development. So far, PLUTO, the plastidic nucleobase transporter from Arabidopsis thaliana is the only known uracil importer at the inner plastidic membrane which represents the permeability barrier of this organelle. We present the first homology model of PLUTO, the sole plant NCS1 member from Arabidopsis based on the crystal structure of the benzyl hydantoin transporter MHP1 from Microbacterium liquefaciens and validated by molecular dynamics simulations. Polar side chains of residues Glu-227 and backbones of Val-145, Gly-147 and Thr-425 are proposed to form the binding site for the three PLUTO substrates uracil, adenine and guanine. Mutational analysis and competition studies identified Glu-227 as an important residue for uracil and to a lesser extent for guanine transport. A differential response in substrate transport was apparent with PLUTO double mutants E227Q G147Q and E227Q T425A, both of which most strongly affected adenine transport, and in V145A G147Q, which markedly affected guanine transport. These differences could be explained by docking studies, showing that uracil and guanine exhibit a similar binding mode whereas adenine binds deep into the catalytic pocket of PLUTO. Furthermore, competition studies confirmed these results. The present study defines the molecular determinants for PLUTO substrate binding and demonstrates key differences in structure-function relations between PLUTO and other NCS1 family members.

The Anglo-Australian Planet Search. XXV. A Candidate Massive Saturn Analog Orbiting HD 30177

NASA Astrophysics Data System (ADS)

Wittenmyer, Robert A.; Horner, Jonathan; Mengel, M. W.; Butler, R. P.; Wright, D. J.; Tinney, C. G.; Carter, B. D.; Jones, H. R. A.; Anglada-Escudé, G.; Bailey, J.; O'Toole, Simon J.

2017-04-01

We report the discovery of a second long-period giant planet orbiting HD 30177, a star previously known to host a massive Jupiter analog (HD 30177b: a = 3.8 ± 0.1 au, m sin I = 9.7 ± 0.5 M Jup). HD 30177c can be regarded as a massive Saturn analog in this system, with a = 9.9 ± 1.0 au and m sin I = 7.6 ± 3.1 M Jup. The formal best-fit solution slightly favors a closer-in planet at a ˜ 7 au, but detailed n-body dynamical simulations show that configuration to be unstable. A shallow local minimum of longer period, lower eccentricity solutions was found to be dynamically stable, and hence we adopt the longer period in this work. The proposed ˜32 year orbit remains incomplete; further monitoring of this and other stars is necessary to reveal the population of distant gas giant planets with orbital separations a ˜ 10 au, analogous to that of Saturn.

Neutron activation analysis on the surface of the Moon and other terrestrial planets

NASA Astrophysics Data System (ADS)

Golovin, Dmitry; Litvak, Maxim; Kozyrev, S. Alexander; Tretiyakov, Vladislav; Sanin, Anton; Vostrukhin, Andrey; Mitrofanov, Igor; Malakhov, Alexey

Determine of elements composition of the planet subsurface in situ is important scientific task for understanding of origin and formation processes of terrestrial planets, moons and asteroids. Also this study will be very perspective in terms of utilization of mineral resources for future lunar base. Creation of such outpost will open doors for robotic and human exploration in the distant parts of Solar System. ADRON instrument onboard landing platforms Russian near-pole lunar missions (Glob and Resource) will be first example of using Neutron Activation method in space. It will measure nuclear composition of the lunar regolith in the landing sites up to 1 m depth. This instrument is able to use for different planets and conditions. For Venus surface, taking into account short lifetime of spacecraft one or two hours of operation will be enough to perform such measurements. Another good opportunity is using similar instrument on Lunar or Martian rovers for searching of important minerals.

Photochemical aerosol formation in planetary atmospheres: A comparison between Pluto and Titan

NASA Astrophysics Data System (ADS)

Lavvas, Panayotis; Strobel, Darrell F.; Lellouch, Emmanuel; Gurwell, Mark A.; Cheng, Andrew F.; Summers, Michael; Gladstone, Randy

2016-10-01

The New Horizons mission observations have revealed us that Pluto's atmosphere is rich in photochemical hazes that extend to high altitudes above its surface [1], apparently similar to those observed in Titan's atmosphere [2].We use detailed models combining photochemistry and microphysics in order to simulate the aerosol formation and growth in Pluto's atmosphere, as performed for Titan's atmosphere [3]. Here we discuss the possible mechanisms leading to the formation of haze particles in Pluto's atmosphere, and we evaluate the contribution of different growth processes (e.g. coagulation vs. condensation) to the resulting particle properties.Moreover we investigate the role of these particles in the radiative balance of Pluto's atmosphere and we compare the resulting particle properties, with those retrieved for Titan's upper atmosphere based on Cassini observations [4]. We discuss the similarities and difference between Pluto's and Titan's aerosols.[1] Gladstone et al., 2016, Science, 351, 6271[2] West et al., 2015, Titan's Haze, in Titan, Interior, Surface, Atmosphere and Space environment, Cambridge University Press[3] Lavvas et al., 2013, PNAS, pnas.1217059110[4] Lavvas et al., 2015, DPS47, id.205.08

Intrepid: A Mission to Pluto

NASA Technical Reports Server (NTRS)

Behling, Michael; Buchman, Donald; Marcus, Andres; Procopis, Stephanie; Wassgren, Carl; Ziemer, Sarah

1990-01-01

A proposal for an exploratory spacecraft mission to Pluto/Charon system was written in response to the request for proposal for an unmannned probe to pluto (RFP). The design requirements of the RFP are presented and under the guidance of these requirements, the spacecraft Intrepid was designed. The RPF requirement that was of primary importance is the minimization of cost. Also, the reduction of flight time was of extreme importance because the atmosphere of Pluto is expected to collapse close to the Year 2020. If intrepid should arrive after the collapse, the mission would be a failure; for Pluto would be only a solid rock of ice. The topics presented include: (1) scientific instrumentation; (2) mission management, planning, and costing; (3) power and propulsion subsystem; (4) structural subsystem; (5) command, control, and communications; and (6) attitude and articulation control.

Molecular Detectability in Exoplanetary Emission Spectra

NASA Astrophysics Data System (ADS)

Tessenyi, M.; Tinetti, G.; Savini, G.; Pascale, E.

2013-09-01

Of the many recently discovered worlds orbiting distant stars, very little is yet known of their chemical composition. With the arrival of new transit spectroscopy and direct imaging facilities, the question of molecular detectability as a function of signal-to-noise (SNR), spectral resolving power and type of planets has become critical. We study the detectability of key molecules in the atmospheres of a range of planet types, and report on the minimum detectable abundances at fixed spectral resolving power and SNR. The planet types considered — hot Jupiters, hot super-Earths, warm Neptunes, temperate Jupiters and temperate super-Earths — cover most of the exoplanets characterisable today or in the near future. We focus on key atmospheric molecules, such as CH4, CO, CO2, NH3, H2O, C2H2, C2H6, HCN, H2S and PH.

Impact and Cratering History of the Pluto System

NASA Astrophysics Data System (ADS)

Greenstreet, Sarah; Gladman, Brett; McKinnon, William B.

2014-11-01

The observational opportunity of the New Horizons spacecraft fly-through of the Pluto system in July 2015 requires a current understanding of the Kuiper belt dynamical sub-populations to accurately interpret the cratering history of the surfaces of Pluto and its satellites. We use an Opik-style collision probability code to compute impact rates and impact velocity distributions onto Pluto and its binary companion Charon from the Canada-France Ecliptic Plane Survey (CFEPS) model of classical and resonant Kuiper belt populations (Petit et al., 2011; Gladman et al., 2012) and the scattering model of Kaib et al. (2011) calibrated to Shankman et al. (2013). Due to the uncertainty in how the well-characterized size distribution for Kuiper belt objects (with diameter d>100 km) connects to smaller objects, we compute cratering rates using three simple impactor size distribution extrapolations (a single power-law, a power-law with a knee, and a power-law with a divot) as well as the "curvy" impactor size distributions from Minton et al. (2012) and Schlichting et al. (2013). Current size distribution uncertainties cause absolute ages computed for Pluto surfaces to be entirely dependent on the extrapolation to small sizes and thus uncertain to a factor of approximately 6. We illustrate the relative importance of each Kuiper belt sub-population to Pluto's cratering rate, both now and integrated into the past, and provide crater retention ages for several cases. We find there is only a small chance a crater with diameter D>200 km has been created on Pluto in the past 4 Gyr. The 2015 New Horizons fly-through coupled with telescope surveys that cover objects with diameters d=10-100 km should eventually drop current crater retention age uncertainties on Pluto to <30%. In addition, we compute the "disruption timescale" (to a factor of three accuracy) for Pluto's smaller satellites: Styx, Nix, Kerberos, and Hydra.

Constraints on the Mass and Location of Planet 9 set by Range and VLBI Observations of Spacecraft at Saturn

NASA Astrophysics Data System (ADS)

Jacobson, Robert A.; Folkner, William M.; Park, Ryan S.; Williams, James G.

2017-06-01

Batygin and Brown, 2016 AJ, found that all Kuiper belt objects (KBOs) with well determined orbits having periods greater than 4000 years share nearly the same orbital plane and are apsidally aligned. They attribute this orbital clustering to the existence of a distant planet, Planet 9, well beyond Neptune, with a mass roughly ten times that of Earth. If such a planet exists, it would affect the motion of the known solar system planets, in particular Saturn, which is well observed with radiometric ranging from the Voyager and Cassini spacecraft and VLBI observations of Cassini. The current planetary ephemerides do not account for the postulated Planet 9, yet their fit to the observational data shows no obvious effect that could be attributed to neglecting that planet. However, it is possible that the effect could be absorbed by the estimated parameters used to determine the ephemerides. Those parameters include the planetary orbital elements, mass of the Sun, and the masses of the asteroids that perturb the Martian orbit. We recently updated the Voyager and Cassini data sets and extended the latter through 2017 March. We analyze the sensitivity of these data to the tidal perturbations caused by Planet 9 for a range of positions on the sky and tidal parameters (the ratio of the mass of Planet 9 to the cube of its distance from Saturn). We determine an upper bound on the tidal parameter and the most probable directions consistent with the observational data.

Constraints on the Mass and Location of Planet 9 set by Range and VLBI Observations of Cassini

NASA Astrophysics Data System (ADS)

Jacobson, Robert Arthur; Folkner, William; Park, Ryan; Williams, James

2018-04-01

Batygin and Brown, 2016 AJ, found that Kuiper belt objects (KBOs) with well determined orbits having periods greater than 4000 years are apsidally aligned. They attribute this orbital clustering to the existence of a distant planet, Planet 9, well beyond Neptune, with a mass roughly ten times that of Earth. If such a planet exists, it would affect the motion of the known solar system planets, in particular Saturn, which is well observed with radiometric ranging from the Cassini spacecraft and VLBI observations of Cassini. The current planetary ephemerides do not account for the postulated Planet 9, yet their fit to the observational data shows no obvious effect that could be attributed to neglecting that planet. However, it is possible that the effect could be absorbed by the estimated parameters used to determine the ephemerides. Those parameters include the planetary orbital elements, mass of the Sun, and the masses of the asteroids that perturb the Martian orbit. We recently updated the Cassini data set and extended it through the end of the mssion in 2017 September. We analyze the sensitivity of these data to the tidal perturbations caused by the postulated Planet 9 for a range of positions on the sky and tidal parameters (the ratio of the mass of Planet 9 to the cube of its distance from Saturn). We determine an upper bound on the tidal parameter and the most probable directions consistent with the observational data.

Inferring planetary obliquity using rotational and orbital photometry

NASA Astrophysics Data System (ADS)

Schwartz, J. C.; Sekowski, C.; Haggard, H. M.; Pallé, E.; Cowan, N. B.

2016-03-01

The obliquity of a terrestrial planet is an important clue about its formation and critical to its climate. Previous studies using simulated photometry of Earth show that continuous observations over most of a planet's orbit can be inverted to infer obliquity. However, few studies of more general planets with arbitrary albedo markings have been made and, in particular, a simple theoretical understanding of why it is possible to extract obliquity from light curves is missing. Reflected light seen by a distant observer is the product of a planet's albedo map, its host star's illumination, and the visibility of different regions. It is useful to treat the product of illumination and visibility as the kernel of a convolution. Time-resolved photometry constrains both the albedo map and the kernel, the latter of which sweeps over the planet due to rotational and orbital motion. The kernel's movement distinguishes prograde from retrograde rotation for planets with non-zero obliquity on inclined orbits. We demonstrate that the kernel's longitudinal width and mean latitude are distinct functions of obliquity and axial orientation. Notably, we find that a planet's spin axis affects the kernel - and hence time-resolved photometry - even if this planet is east-west uniform or spinning rapidly, or if it is north-south uniform. We find that perfect knowledge of the kernel at 2-4 orbital phases is usually sufficient to uniquely determine a planet's spin axis. Surprisingly, we predict that east-west albedo contrast is more useful for constraining obliquity than north-south contrast.

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Dr. Alan Stern, New Horizons principal investigator, speaks on a panel at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. Scientists discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Dr. Jim Green, Dr. Ed Stone, and Dr. Alan Stern speak on a panel at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. They discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Dr. Ed Stone, Voyager project scientist, speaks on a panel at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. Scientists discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Dr. Jim Green, Director of NASA’s Planetary Division, speaks on a panel at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. Scientists discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

Ice Volcanoes on Pluto?

NASA Image and Video Library

2015-11-10

NASA New Horizons scientists believe that the informally named feature Wright Mons, located south of Sputnik Planum on Pluto, and another, Piccard Mons, could have been formed by the cryovolcanic eruption of ices from beneath Pluto surface. Sputnik Planum on Pluto, is an unusual feature that's about 100 miles (160 kilometers) wide and 13,000 feet (4 kilometers) high. It displays a summit depression (visible in the center of the image) that's approximately 35 miles (56 kilometers) across, with a distinctive hummocky texture on its sides. The rim of the summit depression also shows concentric fracturing. http://photojournal.jpl.nasa.gov/catalog/PIA20155

Spectrophotometry of Pluto-Charon mutual events - Individual spectra of Pluto and Charon

NASA Technical Reports Server (NTRS)

Sawyer, S. R.; Barker, E. S.; Cochran, A. L.; Cochran, W. D.

1987-01-01

Time-resolved spectra of the March 3 and April 4, 1987 mutual events of Pluto and Charon, obtained with spectral coverage from 5500 to 10,000 A with 25-A spectral resolution, are discussed. Charon has a featureless reflectance spectrum, with no evidence of methane absorption. Charon's reflectance appears neutral in color and corresponds to a geometric albedo of about 0.37 at 6000 A. The Pluto reflectance spectrum displays methane absorption bands at 7300, 7900, 8400, 8600, and 8900 A and is red in color, with a geometric albedo of about 0.56 at 6000 A.

Swarmathon 2017

NASA Image and Video Library

2017-04-19

A display at the Kennedy Space Center Visitor Complex describes the purpose of Swarmies. Computer scientists are developing these robots focusing not so much on the hardware, but the software. In the spaceport's annual Swarmathon, students from 12 colleges and universities across the nation were invited to develop software code to operate Swarmies to help find resources when astronauts explore distant planets, such as Mars.

Report from the Third Planet: Detect Temperature Inversions and Meteors with a Television Set.

ERIC Educational Resources Information Center

Helms, Harry L.

1991-01-01

Described is how an ordinary FM radio or television receiver can indicate when a meteor streaks overhead by receiving distant broadcast signals. Temperature inversions and the presence of ionized clouds can also be detected using receivers. Information on the troposphere and ionosphere and directions for the activity are included. (KR)

Pluto at High Noon Artist Concept

NASA Image and Video Library

2015-06-08

Just how dim is the sunlight on Pluto, some three billion miles away? This artist concept of the frosty surface of Pluto with Charon and our sun as backdrops illustrates that while sunlight is much weaker than it is here on Earth, it isnt as dark as you might expect. http://photojournal.jpl.nasa.gov/catalog/PIA19682

Astrometric and Geodetic Properties of Earth and the Solar System

NASA Technical Reports Server (NTRS)

Yoder, Charles F.

1995-01-01

The mass, size and shape of planets and their satellites and are essential information from which one can consider the balance of gravity and tensile strength, chemical makeup and such factors as internal temperature or porosity. Orbits and planetary rotation are also useful clues concerning origin, internal structure and tidal history. The tables compiled here include some of the latest results such as detection of densities of Pluto-Charon from analysis of HST images and the latest results for Venus' shape, gravity field and pole orientation based on Magellan spacecraft data. Data concerning prominent asteroids, comets and Sun are also included. Most of the material here is presented as tables. They are preceded by brief explanations of the relevant geophysical and orbit parameters. More complete explanations can be found in any of several reference texts on geodesy, geophysics and celestial mechanics.

Solar System Studies in the Infrared with the Spitzer Space Telescope

NASA Technical Reports Server (NTRS)

Cruikshank, D. P.; Stansberry, J. A.; Cleve, J. Van; Burgdorf, M. J.; Fernandez, Y. R.; Meadows, V. S.; Reach, W. T.

2004-01-01

The Spitzer Space Telescope, formerly known as SIRTF, is a cryogenic telescope (85 cm diameter) operating in a heliocentric orbit trailing the Earth. Its three instruments provide capabilities for spectroscopy, wide-field and small-field imaging at many wavelengths in the range 3.5-160 microns. Observations to be executed in the first two years in programs defined by the Guaranteed Time Observer (GTO) group (the authors of this presentation) consist of photometry, spectroscopy, and radiometry of many Solar System objects, including Titan and other satellites of the outer planets, Pluto, Centaurs, trans-Neptunian objects, comers, asteroids, Uranus, and Neptune. At the time of the preparation of this abstract, some preliminary observations have been made, but the final calibration and reduction of the data are still in progress. The latest results of the Solar System investigations will be presented here.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kikuchi, Akihiro; Higuchi, Arika; Ida, Shigeru, E-mail: kikuchi.a@geo.titech.ac.jp, E-mail: higuchia@geo.titech.ac.jp, E-mail: ida@elsi.jp

Recently, gas giant planets in nearly circular orbits with large semimajor axes (a ∼ 30-1000 AU) have been detected by direct imaging. We have investigated orbital evolution in a formation scenario for such planets, based on a core accretion model. (1) Icy cores accrete from planetesimals at ≲ 30 AU, (2) they are scattered outward by an emerging nearby gas giant to acquire highly eccentric orbits, and (3) their orbits are circularized through the accretion of disk gas in outer regions, where they spend most of their time. We analytically derived equations to describe the orbital circularization through gas accretion.more » Numerical integrations of these equations show that the eccentricity decreases by a factor of more than 5 while the planetary mass increases by a factor of 10. Because runaway gas accretion increases planetary mass by ∼10-300, the orbits are sufficiently circularized. On the other hand, a is reduced at most only by a factor of two, leaving the planets in the outer regions. If the relative velocity damping by shock is considered, the circularization slows down, but is still efficient enough. Therefore, this scenario potentially accounts for the formation of observed distant jupiters in nearly circular orbits. If the apocenter distances of the scattered cores are larger than the disk sizes, their a shrink to a quarter of the disk sizes; the a-distribution of distant giants could reflect the outer edges of the disks in a similar way that those of hot jupiters may reflect inner edges.« less

PLUTO AND CHARON WITH THE HUBBLE SPACE TELESCOPE. I. MONITORING GLOBAL CHANGE AND IMPROVED SURFACE PROPERTIES FROM LIGHT CURVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buie, Marc W.; Young, Eliot F.; Young, Leslie A.

We present new light-curve measurements of Pluto and Charon taken with the Advanced Camera for Surveys High-resolution Camera on the Hubble Space Telescope. The observations were collected from 2002 June to 2003 June at 12 distinct sub-Earth longitudes over a range of solar phase angle 0.{sup 0}36-1.{sup 0}74-a larger range than previously measured. The new measurements of Pluto show that the light-curve amplitude has decreased since the mutual event season in the late 1980s. We also show that the average brightness has increased in the F555W (Johnson V equivalent) passband while the brightness has decreased in the F435W (Johnson Bmore » equivalent) passband. These data thus indicate a substantial reddening of the reflected light from Pluto. We find a weighted mean (B - V) = 0.9540 {+-} 0.0010 that is considerably higher than the long-standing value of (B - V) = 0.868 {+-} 0.003 most recently measured in 1992-1993. This change in color cannot be explained by the evolving viewing geometry and provides the strongest evidence to date for temporal changes on the surface of Pluto that are expected to be linked to volatile transport processes. We also report on the discovery of a new rotational modulation of Pluto's hemispherical color that ranges from 0.92 to 0.98 with the least red color at the longitude of maximum light and most red at minimum light. The phase coefficient of Pluto is nearly the same as measured in 1992-1993 with a value of {beta} {sub B} = 0.0392 {+-} 0.0064 and {beta} {sub V} = 0.0355 {+-} 0.0045 mag deg{sup -1} for the F435W and F555W data, respectively. The Pluto phase curve is still very close to linear but a small but significant nonlinearity is seen in the data. In contrast, the light curve of Charon is essentially the same as in 1992/1993, albeit with much less noise. We confirm that Charon's Pluto-facing hemisphere is 8% brighter than the hemisphere facing away from Pluto. The color of Charon is independent of longitude and has a mean weighted value of (B - V) = 0.7315 {+-} 0.0013. The phase curve for Charon is now shown to be strongly nonlinear and wavelength dependent. We present results for both Pluto and Charon that better constrain the single-particle scattering parameters from the Hapke scattering theory.« less

Pluto's Volatile Transport

NASA Astrophysics Data System (ADS)

Young, Leslie

2012-10-01

Pluto's varying subsolar latitude and heliocentric distance leads to large variations in the surface volatile distribution and surface pressure. I present results of new volatile transport models (Young 2012a, b). The models include insolation, thermal emission, subsurface conduction, heating of a volatile slab, internal heat flux, latent heat of sublimation, and strict global mass balance. Numeric advances include initial conditions that allow for rapid convergence, efficient computation with matrix arithmetic, and stable Crank-Nicholson timesteps for both bare and volatile-covered areas. Runs of the model show six distinct seasons on Pluto. (1) As Pluto approaches perihelion, the volatiles on the old winter pole (the Rotational North Pole, RNP) becomes more directly illuminated , and the pressure and albedo rise rapidly. (2) When a new ice cap forms on the Rotational South Pole, RSP, volatiles are exchanged between poles. The pressure and albedo change more slowly. (3) When all volatiles have sublimed from the RNP, the albedo and pressure drop rapidly. (4-6) A similar pattern is repeated near aphelion with a reversal of the roles and the poles. I will compare results with earlier Pluto models of Hansen and Paige (1996), show the dependence on parameters such as substrate inertia, and make predictions for the New Horizons flyby of Pluto in 2015. This work was supported, in part, by funding from NASA Planetary Atmospheres Grant NNG06GF32G and the Spitzer project (JPL research support Agreement 1368573). Hansen, C. J. and D. A. Paige 1996. Seasonal Nitrogen Cycles on Pluto. Icarus 120, 247-265. Young, L. A. 2012a. Volatile transport on inhomogeneous surfaces: I - Analytic expressions, with application to Pluto’s day. Icarus, in press Young, L. A. 2012b. Volatile transport on inhomogeneous surfaces: II. Numerical calculations, with application to Pluto's season. In preparation.

PLUTO AND CHARON WITH THE HUBBLE SPACE TELESCOPE. II. RESOLVING CHANGES ON PLUTO'S SURFACE AND A MAP FOR CHARON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buie, Marc W.; Young, Eliot F.; Young, Leslie A.

We present new imaging of the surface of Pluto and Charon obtained during 2002-2003 with the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) instrument. Using these data, we construct two-color albedo maps for the surfaces of both Pluto and Charon. Similar mapping techniques are used to re-process HST/Faint Object Camera (FOC) images taken in 1994. The FOC data provide information in the ultraviolet and blue wavelengths that show a marked trend of UV-bright material toward the sunlit pole. The ACS data are taken at two optical wavelengths and show widespread albedo and color variegation on the surface ofmore » Pluto and hint at a latitudinal albedo trend on Charon. The ACS data also provide evidence for a decreasing albedo for Pluto at blue (435 nm) wavelengths, while the green (555 nm) data are consistent with a static surface over the one-year period of data collection. We use the two maps to synthesize a true visual color map of Pluto's surface and investigate trends in color. The mid- to high-latitude region on the sunlit pole is, on average, more neutral in color and generally higher albedo than the rest of the surface. Brighter surfaces also tend to be more neutral in color and show minimal color variations. The darker regions show considerable color diversity arguing that there must be a range of compositional units in the dark regions. Color variations are weak when sorted by longitude. These data are also used to constrain astrometric corrections that enable more accurate orbit fitting, both for the heliocentric orbit of the barycenter and the orbit of Pluto and Charon about their barycenter.« less

Pluto's Atmosphere, Then and Now

NASA Astrophysics Data System (ADS)

Elliot, J. L.; Buie, M.; Person, M. J.; Qu, S.

2002-09-01

The KAO light curve for the 1988 stellar occultation by Pluto exhibits a sharp drop just below half light, but above this level the light curve is consistent with that of an isothermal atmosphere (T = 105 +/- 8 K, with N2 as its major constituent). The sharp drop in the light curve has been interpreted as being caused by: (i) a haze layer, (ii) a large thermal gradient, or (iii) some combination of these two. Modeling Pluto's atmosphere with a haze layer yields a normal optical depth >= 0.145 (Elliot & Young 1992, AJ 103, 991). On the other hand, if Pluto's atmosphere is assumed to be clear, the occultation light curve can be inverted with a new method that avoids the large-body approximations. Inversion of the KAO light curve with this method yields an upper isothermal part, followed by a sharp thermal gradient that reaches a maximum magnitude of -3.9 +/- 0.6 K km-1 at the end of the inversion (r = 1206 +/- 10 km). Even though we do not yet understand the cause of the sharp drop, the KAO light curve can be used as a benchmark for examining subsequent Pluto occultation light curves to determine whether Pluto's atmospheric structure has changed since 1988. As an example, the Mamiña light curve for the 2002 July 20 Pluto occultation of P126A was compared with the KAO light curve by Buie et al. (this conference), who concluded that Pluto's atmospheric structure has changed significantly since 1988. Further analysis and additional light curves from this and subsequent occultations (e.g. 2002 August 21) will allow us to elucidate the nature of these changes. This work was supported, in part, by grants from NASA (NAG5-9008 and NAG5-10444) and NSF (AST-0073447).

The Orbits and Masses of Pluto's Satellites

NASA Astrophysics Data System (ADS)

Brozovic, Marina; Jacobson, R. A.

2013-05-01

Abstract (2,250 Maximum Characters): We report on the numerically integrated orbital fits of Pluto's satellites, Charon, Nix, Hydra, and S/2011 (134340) 1, to an extensive set of astrometric, mutual event, and stellar occultation observations over the time interval April 1965 to July 2011. The observations of Charon relative to Pluto have been corrected for the Pluto center-of-figure center-of-light (COF) offset due to the Pluto albedo variations. The most recently discovered satellite S/2012 (134340) 1 is fit with a precessing ellipse because its observation set is insufficient to constrain a numerically integrated orbit. The Pluto system mass is well determined with the current data. However, the Charon’s mass still carries a considerable amount of the uncertainty due to the fact that the primary source of information for the Charon mass is a small quantity of absolute position measurements that are sensitive to the independent motions of Pluto and Charon about the system barycenter. We used bounded-least squares algorithm to try to constrain the masses of Nix, Hydra, and S/2011 (134340) 1, but the current dataset appears to be too sparse for mass determination. The long-term dynamical interaction among the satellites does yield a weak determination of Hydra's mass. We investigated the effect of more astrometry of S/2012 (134340) 1 on the mass determination of the other satellites and found no improvement with the additional data. We have delivered ephemerides based on our integrated orbits to the New Horizons project along with their expected uncertainties at the time of the spacecraft encounter with the Pluto system. Acknowledgments: The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Observation of solar-system objects with the ISO satellite

NASA Astrophysics Data System (ADS)

Encrenaz, Therese

1998-09-01

The ISO (Infrared Space Observatory) mission was an ESA earth-orbiting satellite devoted to the infrared observation of astronomical sources. The 60-cm helium-cooled telescope was launched in November 1995 and ended its life in May 1998. The satellite was equipped with 4 focal-plane instruments: a camera (CAM, 2.5-17 microns), a photometer (PHT, 2-200 microns) and two spectrometers, SWS (2.3-45 microns) and LWS (45-180 microns). A description of the ISO mission can be found in Kessler et al.(A&A 315 L27, 1996). Observations with ISO have been performed on all classes of solar-system objects. Several important discoveries have been obtained from the ISO data, in particular with the SWS instrument. A few of them are listed below: (1) a new determination of D/H on the four giant planets; (2) the discovery of an external source of water in the stratospheres of the giant planets and Titan; (3) the detection of CO_2 in the stratospheres of Jupiter, Saturn and Neptune; (4) the detection of new hydrocarbons (CH_3C_2H, C_4H_2, C_6H_6, CH_3) in Saturn's stratosphere; (5) the detection of tropospheric water in Saturn; (6) the detection of CO_2 in comet Hale-Bopp at far heliocentric distances (4.6 AU); (7) the first detection of forsterite (Mg_2SiO_4) in the dust of comet Hale-Bopp; (7) the determination of the formation temperature of comets Hale-Bopp and Hartley 2 (27 K and 35 K respectively) from the measurement of the ortho-para ratio in their H_2O nu _3 emission lines. In addition, ISO spectra of Titan, Io and the other galilean satellites, and asteroids were also recorded; IR photometry was achieved on Pluto, distant comets and zodiacal light. Preliminary results can be found in Crovisier et al. (A&A 315 L385, 1996; Science 275 1904, 1996), Encrenaz et al. (A&A 315 L397, 1996; A&A 333 L43, 1998), de Graauw et al. (A&A 321 L13, 1997), Feuchtgruber et al. (Nature 389 159, 1997), Griffin et al. (A&A 315 L389, 1996), Davis et al. (A&A 315 L393, 1996), Reach et al. (A&A 315 L381, 1996), Bezard et al. (A&A 334 L41, 1998) and Coustenis et al. (A&A 336 L85, 1998).

The atmosphere of Pluto as observed by New Horizons

NASA Astrophysics Data System (ADS)

Gladstone, G. Randall; Stern, S. Alan; Ennico, Kimberly; Olkin, Catherine B.; Weaver, Harold A.; Young, Leslie A.; Summers, Michael E.; Strobel, Darrell F.; Hinson, David P.; Kammer, Joshua A.; Parker, Alex H.; Steffl, Andrew J.; Linscott, Ivan R.; Parker, Joel Wm.; Cheng, Andrew F.; Slater, David C.; Versteeg, Maarten H.; Greathouse, Thomas K.; Retherford, Kurt D.; Throop, Henry; Cunningham, Nathaniel J.; Woods, William W.; Singer, Kelsi N.; Tsang, Constantine C. C.; Schindhelm, Eric; Lisse, Carey M.; Wong, Michael L.; Yung, Yuk L.; Zhu, Xun; Curdt, Werner; Lavvas, Panayotis; Young, Eliot F.; Tyler, G. Leonard; Bagenal, F.; Grundy, W. M.; McKinnon, W. B.; Moore, J. M.; Spencer, J. R.; Andert, T.; Andrews, J.; Banks, M.; Bauer, B.; Bauman, J.; Barnouin, O. S.; Bedini, P.; Beisser, K.; Beyer, R. A.; Bhaskaran, S.; Binzel, R. P.; Birath, E.; Bird, M.; Bogan, D. J.; Bowman, A.; Bray, V. J.; Brozovic, M.; Bryan, C.; Buckley, M. R.; Buie, M. W.; Buratti, B. J.; Bushman, S. S.; Calloway, A.; Carcich, B.; Conard, S.; Conrad, C. A.; Cook, J. C.; Cruikshank, D. P.; Custodio, O. S.; Ore, C. M. Dalle; Deboy, C.; Dischner, Z. J. B.; Dumont, P.; Earle, A. M.; Elliott, H. A.; Ercol, J.; Ernst, C. M.; Finley, T.; Flanigan, S. H.; Fountain, G.; Freeze, M. J.; Green, J. L.; Guo, Y.; Hahn, M.; Hamilton, D. P.; Hamilton, S. A.; Hanley, J.; Harch, A.; Hart, H. M.; Hersman, C. B.; Hill, A.; Hill, M. E.; Holdridge, M. E.; Horanyi, M.; Howard, A. D.; Howett, C. J. A.; Jackman, C.; Jacobson, R. A.; Jennings, D. E.; Kang, H. K.; Kaufmann, D. E.; Kollmann, P.; Krimigis, S. M.; Kusnierkiewicz, D.; Lauer, T. R.; Lee, J. E.; Lindstrom, K. L.; Lunsford, A. W.; Mallder, V. A.; Martin, N.; McComas, D. J.; McNutt, R. L.; Mehoke, D.; Mehoke, T.; Melin, E. D.; Mutchler, M.; Nelson, D.; Nimmo, F.; Nunez, J. I.; Ocampo, A.; Owen, W. M.; Paetzold, M.; Page, B.; Pelletier, F.; Peterson, J.; Pinkine, N.; Piquette, M.; Porter, S. B.; Protopapa, S.; Redfern, J.; Reitsema, H. J.; Reuter, D. C.; Roberts, J. H.; Robbins, S. J.; Rogers, G.; Rose, D.; Runyon, K.; Ryschkewitsch, M. G.; Schenk, P.; Sepan, B.; Showalter, M. R.; Soluri, M.; Stanbridge, D.; Stryk, T.; Szalay, J. R.; Tapley, M.; Taylor, A.; Taylor, H.; Umurhan, O. M.; Verbiscer, A. J.; Versteeg, M. H.; Vincent, M.; Webbert, R.; Weidner, S.; Weigle, G. E.; White, O. L.; Whittenburg, K.; Williams, B. G.; Williams, K.; Williams, S.; Zangari, A. M.; Zirnstein, E.

2016-03-01

Observations made during the New Horizons flyby provide a detailed snapshot of the current state of Pluto's atmosphere. Whereas the lower atmosphere (at altitudes of less than 200 kilometers) is consistent with ground-based stellar occultations, the upper atmosphere is much colder and more compact than indicated by pre-encounter models. Molecular nitrogen (N2) dominates the atmosphere (at altitudes of less than 1800 kilometers or so), whereas methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) are abundant minor species and likely feed the production of an extensive haze that encompasses Pluto. The cold upper atmosphere shuts off the anticipated enhanced-Jeans, hydrodynamic-like escape of Pluto's atmosphere to space. It is unclear whether the current state of Pluto's atmosphere is representative of its average state - over seasonal or geologic time scales.

The atmosphere of Pluto as observed by New Horizons.

PubMed

Gladstone, G Randall; Stern, S Alan; Ennico, Kimberly; Olkin, Catherine B; Weaver, Harold A; Young, Leslie A; Summers, Michael E; Strobel, Darrell F; Hinson, David P; Kammer, Joshua A; Parker, Alex H; Steffl, Andrew J; Linscott, Ivan R; Parker, Joel Wm; Cheng, Andrew F; Slater, David C; Versteeg, Maarten H; Greathouse, Thomas K; Retherford, Kurt D; Throop, Henry; Cunningham, Nathaniel J; Woods, William W; Singer, Kelsi N; Tsang, Constantine C C; Schindhelm, Eric; Lisse, Carey M; Wong, Michael L; Yung, Yuk L; Zhu, Xun; Curdt, Werner; Lavvas, Panayotis; Young, Eliot F; Tyler, G Leonard

2016-03-18

Observations made during the New Horizons flyby provide a detailed snapshot of the current state of Pluto's atmosphere. Whereas the lower atmosphere (at altitudes of less than 200 kilometers) is consistent with ground-based stellar occultations, the upper atmosphere is much colder and more compact than indicated by pre-encounter models. Molecular nitrogen (N2) dominates the atmosphere (at altitudes of less than 1800 kilometers or so), whereas methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) are abundant minor species and likely feed the production of an extensive haze that encompasses Pluto. The cold upper atmosphere shuts off the anticipated enhanced-Jeans, hydrodynamic-like escape of Pluto's atmosphere to space. It is unclear whether the current state of Pluto's atmosphere is representative of its average state--over seasonal or geologic time scales. Copyright © 2016, American Association for the Advancement of Science.

Pluto Majestic Mountains, Frozen Plains and Foggy Hazes

NASA Image and Video Library

2015-09-17

Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA's New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto's horizon. The smooth expanse of the informally named icy plain Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. To the right, east of Sputnik, rougher terrain is cut by apparent glaciers. The backlighting highlights more than a dozen layers of haze in Pluto's tenuous but distended atmosphere. The image was taken from a distance of 11,000 miles (18,000 kilometers) to Pluto; the scene is 780 miles (1,250 kilometers) wide. http://photojournal.jpl.nasa.gov/catalog/PIA19948

The Geology of Pluto and Charon Through the Eyes of New Horizons

NASA Technical Reports Server (NTRS)

Moore, J. M.; McKinnon, W. B.; Spencer, J. R.; Howard, A. D.; Schenk, P. M.; Beyer, R. A.; Nimmo, F.; Singer, K. N.; Umurhan, O. M.; White, O. L.;

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Audience members view slides from a presentation by Dr. Jim Green, Dr. Ed Stone, and Dr. Alan Stern at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. They discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

Kuiper Belt Objects Along the Pluto-Express Path

NASA Technical Reports Server (NTRS)

Jewitt, David (Principal Investigator)

1997-01-01

The science objective of this work is to identify objects in the Kuiper Belt which will, in the 5 years following Pluto encounter, be close to the flight path of NASA's Pluto Express. Our hope is that we will find a Kuiper Belt object or objects close enough that a spacecraft flyby will be possible. If we find a suitable object, the science yield of Pluto Express will be substantially enhanced. The density of objects in the Kuiper Belt is such that we are reasonably likely to find an object close enough to the flight path that on-board gas thrusters can effect a close encounter.

Charon/Pluto Mass Ratio Obtained with HST CCD Observations in 1991 and 1993

NASA Technical Reports Server (NTRS)

Null, George W.

1995-01-01

We have analyzed Hubble Space Telescope wide field camera observations of Pluto, Charon, and a reference star, acquired in 1991 and 1993, to observe Pluto's barycentric motion and determine the Charon/Pluto mass ratio, q = 0.1237 +/-0.0081, with 6.5% accuracy. Solution values for Charon orbital elements include the semimajor axis, a = 19662 +/-81 km; inclination, i = 96.57 +/-0.24 deg; eccentricity, e = 0.0072 +/-0.0067; longitude of periapsis, w = 2 +/-35 deg; and mean longitude, l = 123.58 +/-0.43 deg. These elements are referred to the J2000 Earth equator and equinox at epoch JED 2446600.5.

Looking over Pluto

NASA Image and Video Library

2015-09-10

This synthetic perspective view of Pluto, based on the latest high-resolution images to be downlinked from NASA's New Horizons spacecraft, shows what you would see if you were approximately 1,100 miles (1,800 kilometers) above Pluto's equatorial area, looking northeast over the dark, cratered, informally named Cthulhu Regio toward the bright, smooth, expanse of icy plains informally called Sputnik Planum. The entire expanse of terrain seen in this image is 1,100 miles (1,800 kilometers) across. The images were taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). http://photojournal.jpl.nasa.gov/catalog/PIA19937

The formation of Charon's red poles from seasonally cold-trapped volatiles

NASA Astrophysics Data System (ADS)

Grundy, W. M.; Cruikshank, D. P.; Gladstone, G. R.; Howett, C. J. A.; Lauer, T. R.; Spencer, J. R.; Summers, M. E.; Buie, M. W.; Earle, A. M.; Ennico, K.; Parker, J. Wm.; Porter, S. B.; Singer, K. N.; Stern, S. A.; Verbiscer, A. J.; Beyer, R. A.; Binzel, R. P.; Buratti, B. J.; Cook, J. C.; Dalle Ore, C. M.; Olin, C. B.; Parker, A. H.; Protopapa, S.; Quirico, E.; Retherford, K. D.; Robbins, S. J.; Schmitt, B.; Stansberry, J. A.; Umurhan, O. M.; Weaver, H. A.; Young, L. A.; Zangari, A. M.; Bray, V. J.; Cheng, A. F.; McKinnon, W. B.; McNutt, R. L.; Morre, J. M.; Nimmo, F.; Reuter, D. C.; Schenk, P. M.; New Horizons Science Team; Stern, S. A.; Bagenal, F.; Ennico, K.; Gladstone, G. R.; Grundy, W. M.; McKinnon, W. B.; Moore, J. M.; Olkin, C. B.; Spencer, J. R.; Weaver, H. A.; Young, L. A.; Andert, T.; Barnouin, O.; Beyer, R. A.; Binzel, R. P.; Bird, M.; Bray, V. J.; Brozovic, M.; Buie, M. W.; Buratti, B. J.; Cheng, A. F.; Cook, J. C.; Cruikshank, D. P.; Dalle Ore, C. M.; Earler, A. M.; Elliott, H. A.; Greathouse, T. K.; Hahn, M.; Hamilton, D. P.; Hill, M. E.; Hinson, D. P.; Hofgartner, J.; Horányi, M.; Howard, A. D.; Howett, C. J. A.; Jennings, D. E.; Kammer, J. A.; Kollmann, P.; Lauer, T. R.; Lavvas, P.; Linscott, I. R. Lisse, C. M.; Lunsford, A. W.; McComas, D. J.; McNutt, R. L., Jr.; Mutchler, M.; Nimmo, F.; Nunez, J. I.; Paetzold, M.; Parker, A. H.; Parker, J. Wm.; Philippe, S.; Piquette, M.; Porter, S. B.; Protopapa, S.; Quirico, E.; Reitsema, H. J.; Reuter, D. C.; Robbins, S. J.; Roberts, J. H.; Runyon, K.; Schenk, P. M.; Schindhelm, E.; Schmitt, B.; Showalter, M. R.; Singer, K. N.; Stansberry, J. A.; Steffl, A. J.; Strobel, D. F.; Stryk, T.; Summers, M. E.; Szalay, J. R.; Throop, H. B.; Tsang, C. C. C.; Tyler, G. L.; Umurhan, O. M.; Verbiscer, A. J.; Versteeg, M. H.; Weigle, G. E., II; White, O. L.; Woods, W. W.; Young, E. F.; Zangari, A. M.

2016-11-01

A unique feature of Pluto's large satellite Charon is its dark red northern polar cap. Similar colours on Pluto's surface have been attributed to tholin-like organic macromolecules produced by energetic radiation processing of hydrocarbons. The polar location on Charon implicates the temperature extremes that result from Charon's high obliquity and long seasons in the production of this material. The escape of Pluto's atmosphere provides a potential feedstock for a complex chemistry. Gas from Pluto that is transiently cold-trapped and processed at Charon's winter pole was proposed as an explanation for the dark coloration on the basis of an image of Charon's northern hemisphere, but not modelled quantitatively. Here we report images of the southern hemisphere illuminated by Pluto-shine and also images taken during the approach phase that show the northern polar cap over a range of longitudes. We model the surface thermal environment on Charon and the supply and temporary cold-trapping of material escaping from Pluto, as well as the photolytic processing of this material into more complex and less volatile molecules while cold-trapped. The model results are consistent with the proposed mechanism for producing the observed colour pattern on Charon.

The New Horizons Bistatic Radio Science Experiment to Measure Pluto's Surface Properties

NASA Astrophysics Data System (ADS)

Linscott, I.; Hinson, D. P.; Tyler, G. L.; Vincent, M.

2014-12-01

The New Horizons (NH) payload includes a Radio Science Experiment (REX) for principally occultation and radiometric measurement of Pluto and Charon during the flyby in July 2015. The REX subsystem is contained, together with the NH X-Band radio, in the Integrated Electronics Module (IEM) in the New Horizons spacecraft. REX samples and records in two polarizations both total RF power in a 4.5 MHz bandwidth, and radio signal waveforms in a narrow, 1.25 kHz band. During the encounter, and at closest approach to Pluto, the spacecraft's high gain antenna (HGA) will scan Pluto's equatorial latitudes, intercepting the specular zone, a region near Pluto's limb that geometrically favors reflection from the earth's direction. At the same time, a powerful 80 kW uplink beacon will have been transmitted from earth by the DSN to arrive at Pluto during spacecraft closest approach. Reflection from the specular zone is expected to be sufficiently strong to observe the bistatic uplink in the REX narrowband record. Measurements in both polarizations will then be combined to yield surface reflectivity, roughness and limits on the dielectric constant in the specular zone.

The Formation of Charon's Red Poles from Seasonally Cold-Trapped Volatiles

NASA Technical Reports Server (NTRS)

Grundy, W. M.; Cruikshank, D. P.; Gladstone, D. R.; Howett, C. J. A.; Lauer, T. R.; Spencer, J. R.; Summers, M. E.; Buie, M. W.; Earle, A. M.; Ennico, K.;

The formation of Charon's red poles from seasonally cold-trapped volatiles.

PubMed

Grundy, W M; Cruikshank, D P; Gladstone, G R; Howett, C J A; Lauer, T R; Spencer, J R; Summers, M E; Buie, M W; Earle, A M; Ennico, K; Parker, J Wm; Porter, S B; Singer, K N; Stern, S A; Verbiscer, A J; Beyer, R A; Binzel, R P; Buratti, B J; Cook, J C; Dalle Ore, C M; Olkin, C B; Parker, A H; Protopapa, S; Quirico, E; Retherford, K D; Robbins, S J; Schmitt, B; Stansberry, J A; Umurhan, O M; Weaver, H A; Young, L A; Zangari, A M; Bray, V J; Cheng, A F; McKinnon, W B; McNutt, R L; Moore, J M; Nimmo, F; Reuter, D C; Schenk, P M

2016-11-03

A unique feature of Pluto's large satellite Charon is its dark red northern polar cap. Similar colours on Pluto's surface have been attributed to tholin-like organic macromolecules produced by energetic radiation processing of hydrocarbons. The polar location on Charon implicates the temperature extremes that result from Charon's high obliquity and long seasons in the production of this material. The escape of Pluto's atmosphere provides a potential feedstock for a complex chemistry. Gas from Pluto that is transiently cold-trapped and processed at Charon's winter pole was proposed as an explanation for the dark coloration on the basis of an image of Charon's northern hemisphere, but not modelled quantitatively. Here we report images of the southern hemisphere illuminated by Pluto-shine and also images taken during the approach phase that show the northern polar cap over a range of longitudes. We model the surface thermal environment on Charon and the supply and temporary cold-trapping of material escaping from Pluto, as well as the photolytic processing of this material into more complex and less volatile molecules while cold-trapped. The model results are consistent with the proposed mechanism for producing the observed colour pattern on Charon.

Formation of the Sputnik Planum basin and the thickness of Pluto's subsurface ocean

NASA Astrophysics Data System (ADS)

Johnson, B. C.; Bowling, T.; Trowbridge, A.; Freed, A. M.

2016-12-01

Since the New Horizons flyby, evidence has been mounting that Pluto's Sputnik Planum (SP; informal name) (1,2) is associated with a 800-1000 km diameter elliptical impact basin (3,4). Global tectonics and the location of SP suggests that Pluto reoriented to align the basin with its tidal axis (4,5). This indicates there is a large positive mass anomaly associated with SP (4,5). However, even with loading of 3-10 km of dense convecting N2 ice (6,7), a positive mass anomaly associated with the deep basin requires that Pluto has a liquid ocean and the ice shell under the basin is substantially thinned (4). Although the possibility of a slowly freezing current day subsurface ocean is supported by thermal modeling (8,9) and the ubiquity of young extensional tectonic features (1), the thickness of the putative ocean is unconstrained. Here, we simulate the SP basin-forming impact into targets with a range of thermal states and ocean thicknesses. We find that SP can only achieve a large positive mass anomaly if Pluto has a more than 100 km thick salty ocean (i.e. ocean density exceeding 1100 kg/m3). This conclusion may help us better understand the composition and thermal evolution of Pluto. 1. Moore, J. M. et al. Science 351,1284-1293 (2016). 2. Stern, S. A. et al. Science 350,aad1815-aad1815 (2015). 3. Schenk, P. M. et al. A Large Impact Origin for Sputnik Planum and Surrounding Terrains, Pluto? AAS/Division for Planetary Sciences Meeting Abstracts 47,(2015). 4. Nimmo, F. et al. Loading, Relaxation, and Tidal Wander at Sputnik Planum, Pluto. 47th Lunar and Planetary Science Conference 47,2207 (2016). 5. Keane, J. T. & Matsuyama, I. Pluto Followed Its Heart: True Polar Wander of Pluto Due to the Formation and Evolution of Sputnik Planum. 47th Lunar and Planetary Science Conference 47,2348 (2016). 6. Trowbridge, A. J., Melosh, H. J., Steckloff, J. K. & Freed, A. M. Nature 534,79-81 (2016). 7. McKinnon, W. B. et al. Nature 534,82-85 (2016). 8. Robuchon, G. & Nimmo, F. Icarus 216,426-439 (2011). 9. Hammond, N. P., Barr, A. C. & Parmentier, E. M. Geophys. Res. Lett. (2016). doi:10.1002/2016GL069220

TOWARD A DETERMINISTIC MODEL OF PLANETARY FORMATION. VII. ECCENTRICITY DISTRIBUTION OF GAS GIANTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ida, S.; Lin, D. N. C.; Nagasawa, M., E-mail: ida@geo.titech.ac.jp, E-mail: lin@ucolick.org, E-mail: nagasawa.m.ad@m.titech.ac.jp

2013-09-20

The ubiquity of planets and diversity of planetary systems reveal that planet formation encompasses many complex and competing processes. In this series of papers, we develop and upgrade a population synthesis model as a tool to identify the dominant physical effects and to calibrate the range of physical conditions. Recent planet searches have led to the discovery of many multiple-planet systems. Any theoretical models of their origins must take into account dynamical interactions between emerging protoplanets. Here, we introduce a prescription to approximate the close encounters between multiple planets. We apply this method to simulate the growth, migration, and dynamicalmore » interaction of planetary systems. Our models show that in relatively massive disks, several gas giants and rocky/icy planets emerge, migrate, and undergo dynamical instability. Secular perturbation between planets leads to orbital crossings, eccentricity excitation, and planetary ejection. In disks with modest masses, two or less gas giants form with multiple super-Earths. Orbital stability in these systems is generally maintained and they retain the kinematic structure after gas in their natal disks is depleted. These results reproduce the observed planetary mass-eccentricity and semimajor axis-eccentricity correlations. They also suggest that emerging gas giants can scatter residual cores to the outer disk regions. Subsequent in situ gas accretion onto these cores can lead to the formation of distant (∼> 30 AU) gas giants with nearly circular orbits.« less

Pluto Close-up, Now in Color

NASA Image and Video Library

2015-12-10

This enhanced color mosaic combines some of the sharpest views of Pluto that NASA's New Horizons spacecraft obtained during its July 14 flyby. The pictures are part of a sequence taken near New Horizons' closest approach to Pluto, with resolutions of about 250-280 feet (77-85 meters) per pixel -- revealing features smaller than half a city block on Pluto's surface. Lower resolution color data (at about 2,066 feet, or 630 meters, per pixel) were added to create this new image. The images form a strip 50 miles (80 kilometers) wide, trending (top to bottom) from the edge of "badlands" northwest of the informally named Sputnik Planum, across the al-Idrisi mountains, onto the shoreline of Pluto's "heart" feature, and just into its icy plains. They combine pictures from the telescopic Long Range Reconnaissance Imager (LORRI) taken approximately 15 minutes before New Horizons' closest approach to Pluto, with -- from a range of only 10,000 miles (17,000 kilometers) -- with color data (in near-infrared, red and blue) gathered by the Ralph/Multispectral Visible Imaging Camera (MVIC) 25 minutes before the LORRI pictures. The wide variety of cratered, mountainous and glacial terrains seen here gives scientists and the public alike a breathtaking, super-high-resolution color window into Pluto's geology. e border between the relatively smooth Sputnik Planum ice sheet and the pitted area, with a series of hills forming slightly inside this unusual "shoreline." http://photojournal.jpl.nasa.gov/catalog/PIA20213

Precise Masses in the WASP-47 System

NASA Astrophysics Data System (ADS)

Vanderburg, Andrew; Becker, Juliette C.; Buchhave, Lars A.; Mortier, Annelies; Lopez, Eric; Malavolta, Luca; Haywood, Raphaëlle D.; Latham, David W.; Charbonneau, David; López-Morales, Mercedes; Adams, Fred C.; Bonomo, Aldo Stefano; Bouchy, François; Collier Cameron, Andrew; Cosentino, Rosario; Di Fabrizio, Luca; Dumusque, Xavier; Fiorenzano, Aldo; Harutyunyan, Avet; Johnson, John Asher; Lorenzi, Vania; Lovis, Christophe; Mayor, Michel; Micela, Giusi; Molinari, Emilio; Pedani, Marco; Pepe, Francesco; Piotto, Giampaolo; Phillips, David; Rice, Ken; Sasselov, Dimitar; Ségransan, Damien; Sozzetti, Alessandro; Udry, Stéphane; Watson, Chris

2017-12-01

We present precise radial velocity observations of WASP-47, a star known to host a hot Jupiter, a distant Jovian companion, and, uniquely, two additional transiting planets in short-period orbits: a super-Earth in a ≈19 hr orbit, and a Neptune in a ≈9 day orbit. We analyze our observations from the HARPS-N spectrograph along with previously published data to measure the most precise planet masses yet for this system. When combined with new stellar parameters and reanalyzed transit photometry, our mass measurements place strong constraints on the compositions of the two small planets. We find that, unlike most other ultra-short-period planets, the inner planet, WASP-47 e, has a mass (6.83 ± 0.66 {M}\\oplus ) and a radius (1.810 ± 0.027 {R}\\oplus ) that are inconsistent with an Earth-like composition. Instead, WASP-47 e likely has a volatile-rich envelope surrounding an Earth-like core and mantle. We also perform a dynamical analysis to constrain the orbital inclination of WASP-47 c, the outer Jovian planet. This planet likely orbits close to the plane of the inner three planets, suggesting a quiet dynamical history for the system. Our dynamical constraints also imply that WASP-47 c is much more likely to transit than a geometric calculation would suggest. We calculate a transit probability for WASP-47 c of about 10%, more than an order of magnitude larger than the geometric transit probability of 0.6%.

The Elephant in the Room: Effects of Distant, Massive Companions on Planetary System Architectures

NASA Astrophysics Data System (ADS)

Knutson, Heather

2016-06-01

Over the past two decades ongoing radial velocity and transit surveys have been astoundingly successful in detecting thousands of new planetary systems around nearby stars. These systems include apparently single gas giant planets on short period orbits, closely packed systems of up to 5-6 “super-Earths”, and relatively empty systems with either one or no small planets interior to 0.5 AU. Despite our success in cataloguing the diverse properties of these systems, we are still struggling to develop narratives that can explain their apparently divergent formation and migration histories. This is in large part due to our lack of knowledge about the potential presence of massive outer companions in these systems, which can play a pivotal role in the shaping the final properties of the inner planets. In my talk I will discuss current efforts to complete the census for known planetary systems by searching for outer gas giant planets with long term radial velocity monitoring and wide separation stellar companions with high contrast imaging and spectroscopy. I will then demonstrate how statistical constraints on this population of outer companions can be used to test current theories for planet formation and migration.

Featured Image: Simulating Planetary Gaps

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-03-01

The authors model of howthe above disk would look as we observe it in a scattered-light image. The morphology of the gap can be used to estimate the mass of the planet that caused it. [Dong Fung 2017]The above image from a computer simulation reveals the dust structure of a protoplanetary disk (with the star obscured in the center) as a newly formed planet orbits within it. A recent study by Ruobing Dong (Steward Observatory, University of Arizona) and Jeffrey Fung (University of California, Berkeley) examines how we can determine mass of such a planet based on our observations of the gap that the planet opens in the disk as it orbits. The authors models help us to better understand how our observations of gaps might change if the disk is inclined relative to our line of sight, and how we can still constrain the mass of the gap-opening planet and the viscosity of the disk from the scattered-light images we have recently begun to obtain of distant protoplanetary disks. For more information, check out the paper below!CitationRuobing Dong () and Jeffrey Fung () 2017 ApJ 835 146. doi:10.3847/1538-4357/835/2/146

All in the Family: What Brown Dwarfs Teach Us About Extrasolar Giant Planets

NASA Technical Reports Server (NTRS)

Marley, M.

2003-01-01

As we await the first direct image of an extrasolar giant planet, we can turn to theory and the experience gained in the campaign to detect and understand brown dwarfs for guidance on what to expect. As with any new arrival to a family, there should be a strong family resemblance (one hopes) along with notable unique features and interesting peculiarities. The 300 or so known L and T dwarfs, combined with our own giant planets, already span much of the effective temperature range within which extrasolar planets will be found. Only objects with thick, easily detectable, water clouds have yet to be seen. Thus we already know much of the family. I will describe what we have learned from studying these objects, focusing on the important roles clouds and atmospheric chemistry play in affecting their atmospheres and emergent spectra. Relying on these findings and theoretical models, I'll sketch out what we can expect from extrasolar giant planets, focusing on easily detectable features. Some wild cards, of course, are to be expected. Photochemical hazes, in particular, may obscure the family traits on the faces of Jupiter's distant cousins and may make one wonder, at least momentarily, about the milkman.

Magnificent Mars 10 Years of Mars Reconnaissance Orbiter

NASA Image and Video Library

2016-03-09

NASA's Mars Reconnaissance Orbiter has clocked more than a decade of service at the Red Planet and has yielded scientific discoveries and magnificent views of a distant world. Video uses spacecraft animation and stills set to music. These images taken by MRO's HiRISE camera are not in true color because they include infrared information in order to be optimized for geological science.

Eating in Space: Food for Thought. EG-2011-08-00005-SSC

ERIC Educational Resources Information Center

Vogt, Gregory L.; Shearer, Deborah A.

2011-01-01

Among the thousands of questions that need to be answered before astronauts travel to distant planets and asteroids are questions related to the astronauts themselves. How much food will they need and what foods can they take? We are fortunate on Earth to have an amazing variety of foods to eat. When astronauts do go to Mars and other…

It's Far, It's Small, It's Cool: It's an Icy Exoplanet!

NASA Astrophysics Data System (ADS)

2006-01-01

Using a network of telescopes scattered across the globe, including the Danish 1.54m telescope at ESO La Silla (Chile), astronomers [1] discovered a new extrasolar planet significantly more Earth-like than any other planet found so far. The planet, which is only about 5 times as massive as the Earth, circles its parent star in about 10 years. It is the least massive exoplanet around an ordinary star detected so far and also the coolest [2]. The planet most certainly has a rocky/icy surface. Its discovery marks a groundbreaking result in the search for planets that support life. ESO PR Photo 03a/06 ESO PR Photo 03a/06 Artist's Impression of the Newly Found Exoplanet The new planet, designated by the unglamorous identifier of OGLE-2005-BLG-390Lb, orbits a red star five times less massive than the Sun and located at a distance of about 20,000 light years, not far from the centre of our Milky Way galaxy. Its relatively cool parent star and large orbit implies that the likely surface temperature of the planet is 220 degrees Centigrade below zero, too cold for liquid water. It is likely to have a thin atmosphere, like the Earth, but its rocky surface is probably deeply buried beneath frozen oceans. It may therefore more closely resemble a more massive version of Pluto, rather than the rocky inner planets like Earth and Venus. "This planet is actually the first and only planet that has been discovered so far that is in agreement with the theories for how our Solar System formed ", said Uffe Gråe Jørgensen (Niels Bohr Institute, Copenhagen, Denmark), member of the team. The favoured theoretical explanation for the formation of planetary systems proposes that solid 'planetesimals' accumulate to build up planetary cores, which then accrete nebular gas - to form giant planets - if they are sufficiently massive. Around red dwarfs, the most common stars of our Galaxy, this model favours the formation of Earth- to Neptune-mass planets being between 1 and 10 times the Earth-Sun distance away from their host. "OGLE-2005-BLG-390Lb is only the third extra-solar planet discovered so far through microlensing searches ", said Jean-Philippe Beaulieu (Institut d'Astrophysique de Paris, France), the lead author. "While the other two microlensing planets have masses of a few times that of Jupiter, the discovery of a 5 Earth mass planet - though much harder to detect than more massive ones - is a strong hint that these lower-mass objects are very common. " Contrary to most exoplanets discovered, OGLE-2005-BLG-390Lb was indeed found using the 'microlensing' technique, based on an effect noted by Albert Einstein in 1912. "With this method, we let the gravity of a dim, intervening star act as a giant natural telescope for us, magnifying a more distant star, which then temporarily looks brighter ", explained team member Andrew Williams (Perth Observatory, Australia). "A small 'defect' in the brightening reveals the existence of a planet around the lens star. We don't see the planet, or even the star that it's orbiting, we just see the effect of their gravity. " Such an intervening star causes a characteristic brightening that lasts about a month. Any planets orbiting this star can produce an additional signal, lasting days for giant planets down to hours for Earth-mass planets. In order to be able to catch and characterize these planets, nearly-continuous round-the-clock high-precision monitoring of ongoing microlensing events is required. This is achieved by the PLANET network of 1m-class telescopes consisting of the ESO 1.54m Danish at La Silla (Chile), the Canopus Observatory 1.0m (Hobart, Tasmania, Australia), the Perth 0.6m (Bickley, Western Australia), the Boyden 1.5m (South Africa), and the SAAO 1.0m (Sutherland, South Africa). Since 2005, PLANET operates a common campaign with RoboNet, a UK operated network of 2m fully robotic telescopes currently comprising the Liverpool Telescope (Roque de Los Muchachos, La Palma, Spain) and the Faulkes Telescope North (Haleakala, Hawaii, USA). ESO PR Photo 03b/06 ESO PR Photo 03b/06 Light Curve of OGLE-2005-BLG-390 The OGLE (Optical Gravitational Lensing Experiment) search team (led by A. Udalski, Warsaw University Observatory, Poland) discovered the event OGLE-2005-BLG-390 on 11 July 2005, triggering the PLANET telescopes to start taking data. A light curve consistent with a single lens star peaking at an amplification of about 3 on 31 July 2005 was observed, until 10 August when PLANET member Pascal Fouqué, observing at the Danish 1.54m at ESO La Silla, noticed a planetary deviation. An OGLE point from the same night showed the same trend, while the last half of the planetary deviation, lasting about a day, had been covered by images from Perth Observatory. The MOA (Microlensing Observations in Astrophysics) collaboration was later able to identify the source star on its images and confirmed the deviation. No other interpretation than the presented sub-Neptune mass planet with its quoted parameters appeared to fit the extensive data set. This discovery brings a fresh look at the field of planetary science. In particular, astronomers now think that such frozen worlds are much more common than their larger, Jupiter-like brethren. "Indeed if Jupiter-like planets were as widespread, the microlensing method should have found dozens of them by now ", said David Bennett (University of Notre Dame, USA), another PLANET team member. The microlensing technique is most probably the only method currently capable of detecting planets similar to Earth. "The search for a second Earth is the driving force behind our research and this discovery constitutes a major leap forward since it is the most Earth-like planet we know of so far ", said co-author Daniel Kubas, from ESO. ESO PR Video 03/06 ESO PR Video 03/06 Learn more with the video! A report has been published in the 26 January 2006 edition of the leading journal Nature ("Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing" by J.-P. Beaulieu, D. P. Bennett, P. Fouqué, A. Williams, M. Dominik, U. G. Jørgensen, D. Kubas et al.). High resolution images and their captions are available on this page. This press release is also accompanied by Broadcast quality material.

New Opportunities for Outer Solar System Science using Radioisotope Electric Propulsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noble, Robert J.; /SLAC; Amini, Rashied

Today, our questions and hypotheses about the Solar System's origin have surpassed our ability to deliver scientific instruments to deep space. The moons of the outer planets, the Trojan and Centaur minor planets, the trans-Neptunian objects (TNO), and distant Kuiper Belt objects (KBO) hold a wealth of information about the primordial conditions that led to the formation of our Solar System. Robotic missions to these objects are needed to make the discoveries, but the lack of deep-space propulsion is impeding this science. Radioisotope electric propulsion (REP) will revolutionize the way we do deep-space planetary science with robotic vehicles, giving themmore » unprecedented mobility. Radioisotope electric generators and lightweight ion thrusters are being developed today which will make possible REP systems with specific power in the range of 5 to 10 W/kg. Studies have shown that this specific power range is sufficient to perform fast rendezvous missions from Earth to the outer Solar System and fast sample return missions. This whitepaper discusses how mobility provided by REP opens up entirely new science opportunities for robotic missions to distant primitive bodies. We also give an overview of REP technology developments and the required next steps to realize REP.« less

Does the Galactic Bulge Have Fewer Planets?

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-12-01

The Milky Ways dense central bulge is a very different environment than the surrounding galactic disk in which we live. Do the differences affect the ability of planets to form in the bulge?Exploring Galactic PlanetsSchematic illustrating how gravitational microlensing by an extrasolar planet works. [NASA]Planet formation is a complex process with many aspects that we dont yet understand. Do environmental properties like host star metallicity, the density of nearby stars, or the intensity of the ambient radiation field affect the ability of planets to form? To answer these questions, we will ultimately need to search for planets around stars in a large variety of different environments in our galaxy.One way to detect recently formed, distant planets is by gravitational microlensing. In this process, light from a distant source star is bent by a lens star that is briefly located between us and the source. As the Earth moves, this momentary alignment causes a blip in the sources light curve that we can detect and planets hosted by the lens star can cause an additional observable bump.Artists impression of the Milky Way galaxy. The central bulge is much denserthan the surroundingdisk. [ESO/NASA/JPL-Caltech/M. Kornmesser/R. Hurt]Relative AbundancesMost source stars reside in the galactic bulge, so microlensing events can probe planetary systems at any distance between the Earth and the galactic bulge. This means that planet detections from microlensing could potentially be used to measure the relative abundances of exoplanets in different parts of our galaxy.A team of scientists led by Matthew Penny, a Sagan postdoctoral fellow at Ohio State University, set out to do just that. The group considered a sample of 31 exoplanetary systems detected by microlensing and asked the following question: are the planet abundances in the galactic bulge and the galactic disk the same?A Paucity of PlanetsTo answer this question, Penny and collaborators derived the expected distribution of host distances from a simulated microlensing survey, correcting for dominant selection effects. They then compared the distribution of distances in this model sample to the distribution of distances measured for the actual, observed systems.Histogram and cumulative distribution (black lines) of distance estimates for microlensing planet hosts. Red lines show the distributions predicted by the model if the disk and bulge abundances were the same. [Penny et al. 2016]Intriguingly, the two distributions dont match when you assume that the planet abundances in the disk and the bulge are the same. The relative abundances appear to be higher in the disk than in the bulge, according to the teams results: the observations agree with a model in which the bulge/disk abundance ratio is less than 0.54.Whats to Blame?There are a few ways to interpret this result: 1) distance measurements for the sample of planets discovered by microlensing have errors, 2) the model is too simplified; it needs to also include dependence of planet abundance and detection sensitivity on properties like host mass and metallicity, or 3) the galactic bulge actually has fewer planets than the disk.Penny and collaboratorssuspect some combination of the first two interpretations is most likely, but an actual paucity of planets in the galactic bulge cant be ruled out. Performing similar analysis on a larger sample of microlensing planets expected from upcoming, second-generation microlensing searches and obtaining more accurate distance measurements will help us to address this puzzlemore definitively in the future.CitationMatthew T. Penny et al 2016 ApJ 830 150. doi:10.3847/0004-637X/830/2/150

Detection of Atmospheric CO on Pluto with ALMA

NASA Astrophysics Data System (ADS)

Gurwell, Mark; Lellouch, Emmanuel; Butler, Bryan; Moullet, Arielle; Moreno, Raphael; Bockelée-Morvan, Dominique; Biver, Nicolas; Fouchet, Thierry; Lis, Darek; Stern, Alan; Young, Leslie; Young, Eliot; Weaver, Hal; Boissier, Jeremie; Stansberry, John

2015-11-01

We observed Pluto and Charon using the Atacama Large Millimeter/submillimeter Array (ALMA) interferometer in Northern Chile on June 12.2 and June 13.15, 2015, just one month prior to the New Horizons flyby of the system. The configuration of ALMA at the time provided ~0.3" resolution, allowing separation of emission from Pluto and Charon. This project targeted multiple science goals, including a search for HCN in Pluto's atmosphere [1] and high precision measurements of the individual brightness temperatures of Pluto and Charon [2], also presented at this meeting. Here we report the high SNR detection of carbon monoxide in the atmosphere of Pluto. The CO(3-2) rotational line, at 345.796 GHz (867 μm), was observed with 117 kHz spectral resolution for 45 min (on-source) on each date, providing ~3.5mJy/channel RMS. CO emission was clearly detected on both days, with a contrast of ~65 mJy above the Pluto continuum, and ~1.8 MHz FWHM linewidth, with the combined integrated line SNR >50. The presence of CO in Pluto's atmosphere is expected due to it's presence as ice on the surface in vapor pressure equilibrium with the atmosphere (e.g. [3],[4]), and it was previously detected at modest SNR in the near-IR using the VLT [5]. A preliminary assessment based upon the CO line wings shows the fractional abundance of CO is 500-750 ppm, consistent with that found in [5]. Further, the shape of the line core emission (assuming a constant CO mixing ratio), suggests that the atmospheric temperature rises quickly from the surface to ~100-110 K in the altitude range 20-70 km but decreases above that, falling to about 70 K by 200 km altitude. A detailed line inversion analysis will be performed and results presented.[1] Lellouch et al, this meeting. [2] Butler et al., this meeting. [3] Owen et al (1993), Science, 261, pp. 745-748. [4] Spencer et al (1993), In Pluto and Charon, pp. 435-473. Univ. of Arizona Press, Tucson. [5] Lellouch et al (2011), A&A, 530, L4.

Modeling Low Velocity Impacts: Predicting Crater Depth on Pluto

NASA Astrophysics Data System (ADS)

Bray, V. J.; Schenk, P.

2014-12-01

The New Horizons mission is due to fly-by the Pluto system in Summer 2015 and provides the first opportunity to image the Pluto surface in detail, allowing both the appearance and number of its crater population to be studied for the first time. Bray and Schenk (2014) combined previous cratering studies and numerical modeling of the impact process to predict crater morphology on Pluto based on current understanding of Pluto's composition, structure and surrounding impactor population. Predictions of how the low mean impact velocity (~2km/s) of the Pluto system will influence crater formation is a complex issue. Observations of secondary cratering (low velocity, high angle) and laboratory experiments of impact at low velocity are at odds regarding how velocity controls depth-diameter ratios: Observations of secondary craters show that these low velocity craters are shallower than would be expected for a hyper-velocity primary. Conversely, gas gun work has shown that relative crater depth increases as impact velocity decreases. We have investigated the influence of impact velocity further with iSALE hydrocode modeling of comet impact into Pluto. With increasing impact velocity, a projectile will produce wider and deeper craters. The depth-diameter ratio (d/D) however has a more complex progression with increasing impact velocity: impacts faster than 2km/s lead to smaller d/D ratios as impact velocity increases, in agreement with gas-gun studies. However, decreasing impact velocity from 2km/s to 300 m/s produced smaller d/D as impact velocity was decreased. This suggests that on Pluto the deepest craters would be produced by ~ 2km/s impacts, with shallower craters produced by velocities either side of this critical point. Further simulations to investigate whether this effect is connected to the sound speed of the target material are ongoing. The complex relationship between impact velocity and crater depth for impacts occurring between 300m/s and 10 km/s suggests that there might be a larger range of 'pristine' crater depths on Pluto than on bodies with higher mean impact velocity. This might affect our ability to define a pristine crater depth as a starting point for crater infill and relaxation studies.

The Pluto System At Small Phase Angles

NASA Astrophysics Data System (ADS)

Verbiscer, Anne J.; Buie, Marc W.; Binzel, Richard; Ennico, Kimberly; Grundy, William M.; Olkin, Catherine B.; Showalter, Mark Robert; Spencer, John R.; Stern, S. Alan; Weaver, Harold A.; Young, Leslie; New Horizons Science Team

2016-10-01

Hubble Space Telescope observations of the Pluto system acquired during the New Horizons encounter epoch (HST Program 13667, M. Buie, PI) span the phase angle range from 0.06 to 1.7 degrees, enabling the measurement and characterization of the opposition effect for Pluto and its satellites at 0.58 microns using HST WFC3/UVIS with the F350LP filter, which has a broadband response and a pivot wavelength of 0.58 microns. At these small phase angles, differences in the opposition effect width and amplitude appear. The small satellites Nix and Hydra both exhibit a very narrow opposition surge, while the considerably larger moon Charon has a broader opposition surge. Microtextural surface properties derived from the shape and magnitude of the opposition surge of each surface contain a record of the collisional history of the system. We combine these small phase angle observations with those made at larger phase angles by the New Horizons Long Range Reconnaissance Imager (LORRI), which also has a broadband response with a pivot wavelength of 0.61 microns, to produce the most complete disk-integrated solar phase curves that we will have for decades to come. Modeling these disk-integrated phase curves generates sets of photometric parameters that will inform spectral modeling of the satellite surfaces as well as terrains on Pluto from spatially resolved New Horizons Ralph Linear Etalon Imaging Spectral Array (LEISA) data from 1.2 to 2.5 microns. Rotationally resolved phase curves of Pluto reveal opposition effects that only appear at phase angles less than 0.1 degree and have widths and amplitudes that are highly dependent on longitude and therefore on Pluto's diverse terrains. The high albedo region informally known as Sputnik Planum dominates the disk-integrated reflectance of Pluto on the New Horizons encounter hemisphere. These results lay the groundwork for observations at true opposition in 2018, when the Pluto system will be observable at phase angles so small that an Earth transit across the solar disk will be visible from Pluto and its satellites.

Geology and Composition of Pluto and Charon from New Horizons

NASA Astrophysics Data System (ADS)

Spencer, John R.; Stern, S. Alan; Moore, Jeffrey M.; Grundy, W. M.; McKinnon, William B.; Cruikshank, Dale P.; Weaver, Harold A.; Olkin, Catherine B.; Young, Leslie; Ennico, Kimberly; New Horizons Geology/Geophysics and Composition Theme Teams

2016-10-01

Data gathered by New Horizons during its July 2015 flyby has revolutionized our understanding of the geology and surface composition of Pluto and Charon. While much of Pluto's ice shell is ancient and rigid, as evinced by locally high crater densities and deep graben, much of the surface has been reworked, up to the present day, by a bewildering variety of geological processes. These include deposition and erosion of kilometers of mantle material, sublimation, apparent cryovolcanism, chaotic breakup of the crust to form rugged mountains, erosion and creation of channel networks by probable glacial action, and active glaciation. Pluto's anti-Charon hemisphere is dominated by 1000 km wide field of actively convecting nitrogen and other ices, informally called Sputnik Planum, occupying a large depression of probable impact origin. Color and composition is very varied, and is dominated by dark red tholins and N2, CH4, and CO ices, with H2O ice bedrock also exposed in many places. Apart from Sputnik Planum, color and composition is strongly correlated with latitude, showing the importance of insolation in controlling ice distribution. Charon shows pervasive extensional tectonism and locally extensive cryovolcanic resurfacing, both dating from early in solar system history. Its color and surface composition, dominated by H2O ice plus NH3 hydrate, is remarkably uniform apart from a thin deposit of dark red material near the north pole which may be due to cold-trapping and radiolysis of hydrocarbons escaping from Pluto. Neither Pluto nor Charon is likely to have experienced tidal heating during the period when observable landforms were created. Charon's surface shows resurfacing comparable in extent and age to many Saturnian and Uranian satellites such as Dione or Ariel, suggesting that observed activity on these satellites may not necessarily be tidally-driven. Pluto demonstrates that resurfacing on small volatile-rich icy bodies can be powered for at least 4.5 Ga by ongoing radiogenic and residual early heat alone, though the fact that Triton shows much more pervasive resurfacing than Pluto provides some evidence that Triton, unlike Pluto, has access to an additional heat source, presumably tidal.

Cosmogonic constraints from densities in the Pluto system and rotational and tidal figures of equilibrium for Pluto and Charon

NASA Astrophysics Data System (ADS)

McKinnon, W.; Buie, M.; Moore, J.; Linscott, I.; Hinson, D.; Tyler, G.; Singer, K.; Stern, S.; New Horizons Team

2014-07-01

A byproduct of the discovery of Nix, Hydra, Styx, and Kerberos, and the detailed study of their orbits, has been a relatively precise determination of the system barycenter, and thus the Pluto/Charon mass ratio [1]. Coupled with precise determinations of Charon's size by multiple stellar occultations [2,3], Charon's mean density is now relatively well-determined (1.72 ± 0.02 g cm^{-3}), both in an absolute sense and with respect to that of Pluto (1.89 ± 0.06 g cm^{-3}) [1]. The latter's precise size remains uncertain due to the effects of its atmosphere on stellar occultations [e.g., 4] and of limb darkening on mutual events [5]. Both Pluto and Charon are relatively rock-rich, but Charon is somewhat icier, which is consistent with impact origin scenarios in which one or both precursor bodies were at least partially differentiated (rock separated from ice under the action of gravity) [6,7]. Ice-rich ejecta is also the preferred route for forming a particle disk outside of Charon's initial post-giant-impact orbit, such as would lead to accretion of the small satellites [8]. In this regard, the upper limits on the densities of the brightest and presumably largest of the small satellites (Nix and Hydra) are - even at the 3σ level -- consistent with very icy and porous bodies. Icy rubble-pile bodies are predicted by the initial conditions of the giant impact as presently understood (conditions necessary to give an icier Charon). The small satellites will thus offer an interesting cosmogonical test during the 14 July 2015 New Horizons encounter, as good constraints will be placed on satellite volumes from imaging and improved satellite masses should result from optical navigation and orbital simulations. The fly-through of the Pluto-Charon system by New Horizons also offers the first opportunity to determine both the total system mass and the individual masses of Pluto and Charon by direct Doppler tracking (although the spacecraft will not pass close enough to any of the small satellites to measure their gravitational accelerations). Simulations of the encounter by the REX Radio Science experiment indicate the potential accuracies of the combined and individual mass determinations of Pluto and Charon are on the order of 0.1 % [9,10], a substantial improvement in precision (especially for Charon). This will put to rest a long-standing limitation on modeling and understanding Pluto and Charon's internal structure and evolution [11]. It is notable, from the densities quoted above, that the ''density gap'' between Pluto and Charon appears to be narrowing, and at the 3σ level and considering the effects of porosity, this gap could even be zero. If Pluto and Charon were close in density after all, it could change our view as to how the binary formed [12]. Refinement at the next level, that is, determining Pluto's or Charon's internal structure, specifically their degree of differentiation (or even the presence or absence of oceans), will not be easy. New Horizons will not pass close enough to measure the degree-2 gravity field for either body (nor was such an original measurement requirement or mission objective), but shape determination from imaging offers the possibility of determining differentiation state. For this to be successful, however, Pluto or Charon must be in hydrostatic equilibrium. For all hydrostatic models of these two bodies, the differences between the lengths of the principal axes of their figures are predicted to be less than 1 km, and the differences between differentiated and undifferentiated models smaller still [13]. Thus, discriminating between the two cases will be challenging. Furthermore, either Pluto or Charon may choose not to cooperate, if they retain fossil hydrostatic figures from earlier in their mutual tidal evolution [14], in the manner of Iapetus [e.g., 15]. These fossil figures would be larger (more biaxial in the case of Pluto, and more triaxial for Charon), and thus much easier to measure, and could provide important clues to Pluto's thermal and structural evolution [16].

Out of the Dust, A Planet is Born Artist Concept

NASA Image and Video Library

2004-05-27

In this artist's conception, a possible newfound planet spins through a clearing in a nearby star's dusty, planet-forming disc. This clearing was detected around the star CoKu Tau 4 by NASA's Spitzer Space Telescope. Astronomers believe that an orbiting massive body, like a planet, may have swept away the star's disc material, leaving a central hole. The possible planet is theorized to be at least as massive as Jupiter, and may have a similar appearance to what the giant planets in our own solar system looked like billions of years ago. A graceful ring, much like Saturn's, spins high above the planet's cloudy atmosphere. The ring is formed from countless small orbiting particles of dust and ice, leftovers from the initial gravitational collapse that formed the possible giant planet. If we were to visit a planet like this, we would have a very different view of the universe. The sky, instead of being the familiar dark expanse lit by distant stars, would be dominated by the thick disc of dust that fills this young planetary system. The view looking toward CoKu Tau 4 would be relatively clear, as the dust in the interior of the disc has fallen into the accreting star. A bright band would seem to surround the central star, caused by light scattered back by the dust in the disc. Looking away from CoKu Tau 4, the dusty disc would appear dark, blotting out light from all the stars in the sky except those which lie well above the plane of the disc. http://photojournal.jpl.nasa.gov/catalog/PIA05988

The 19th of July 2016 Multi-Chord Stellar Occultation by Pluto - A European PRO-AM cooperation

NASA Astrophysics Data System (ADS)

Beisker, W.; Eberle, A.; Gaehrken, B.; Kattentidt, B.; Murawski, G.; Gazeas, K.; Tzouganatos, L.; Tigani, K.; Gloistein, D.; Hampf, D.; Hampf, D.; Eichler, H.; Hattenbach, J.; Guhl, K.; Dohrmann, M.; Krannich, G.; Lindner, P.; Marchini, A.; Papini, R.; Salvaggio, F.; Ohlert, J.; Kloes, O.; Farago, O.; Farago, A.; Grzedzielsk, P.; Signoret, F.; Moravec, Z.; Tsamis, V.; Wortmann, G.; Walzel, K.; Rothe, W.; Bode, H.-J.; Dangl, G.; Berard, D.; Desmars, J.; Leiva, R.; Meza, E.; Assafin, M.; Benedetti-Rossi, G.; Braga Ribas, F.; Camargo, J.; Dias de Oliveira, A.; Gomes Junior, A.; Vieira, R. M.; Ortiz, J. L.; Duffard, R.; Santos-Sanz, P.; Morales, N.; Sicardy, B.

2017-09-01

The occultation of the 14th mag star UCAC4 345-180315 by Pluto on the evening of the 19th of July, 2016 could be observed from large parts of Europe, middle east and northern Africa as well. A campaign had been organized with for many observers and observatories throughout Europe and other countries. Professional as well as amateur observatories and observers shared in a PRO-AM cooperation to achieve the highest possible degree of coverage. The scientific goal was the ongoing monitoring of Pluto's atmosphere, waiting for a possible shrinking of its pressure due to the increasing distance of Pluto from the sun.

Comparative features of volcanoes on Solar system bodies

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.

2018-05-01

The bark of many cosmic bodies is in motion because of the displacement of tectonic plates on magma. Pouring molten magma through cracks in the cortex is called a volcanic eruption. There are two main types of volcanoes: basaltic, appearing where a new material of tectonic plates is formed, and andesitic, which located in the places of destruction of these plates.The third type of volcanoes is cryovolcanoes, or ice volcanoes. This type of volcano ejects matter in the form of ice volcanic melts or steam from water, ammonia, methane. After the eruption, the cryomagma at a low temperature condenses to a solid phase. Cryovolcanoes can be formed on such objects as Pluto, Ceres, Titan, Enceladus, Europe, Triton, etc. Potential sources of energy for melting ice in the production of cryovolcanoes are tidal friction and/or radioactive decay. Semi-transparent deposits of frozen materials that can create a subsurface greenhouse effect, with the possibility of accumulating the required heat with subsequent explosive eruption, are another way to start the cryovolcano action. This type of eruption is observed on Mars and Triton. The first and second types of eruptions (basaltic and andesitic) are characteristic of terrestrial planets (Mercury, Venus, Mars) and for some satellites of the planets of the Solar system.

Structure and other properties of Jupiter's distant magnetotail

NASA Technical Reports Server (NTRS)

Lepping, R. P.; Desch, M. D.; Klein, L. W.; Sittler, E. C., Jr.; Sullivan, J. D.; Kurth, W. S.; Behannon, K. W.

1983-01-01

Analyses of data from Voyager 2 experiments provide evidence for, and characteristics of, a Jovian magnetotail extending at least to 9,000 Jovian radii from the planet. During approximately (25 day) periodic sightings of the tail, the magnetic field tended to point radially towards or away from Jupiter, indicating preservation to large distances of the bipolar, lobe like structure observed near the planet. This periodicity, along with various properties of the solar wind at this time, indicates that the tail is apparently influenced by recurrent solar wind features. Anomalous magnetic fields, not aligned with the nominal tail axis, also exist within the tail, especially in the low density, central (core) region, indicating some complexity of internal structure.

Mass Determination of Pluto and Charon from New Horizon REX Radio Science Observations

NASA Astrophysics Data System (ADS)

Paetzold, Martin; Andert, T. P.; Tyler, G.; Bird, M. K.; Hinson, D. P.; Linscott, I. R.

2013-10-01

The anticipated 14 July 2015 New Horizons fly-through of the Pluto system provides the first opportunity to determine both the total system mass and the individual masses of Pluto and Charon by direct observation. This will be accomplished by use of: i) two-way Doppler radio frequency tracking data during intervals along the fly-in and -out trajectory, and ii) one-way uplink Doppler frequency recorded by the on-board radio science instrument, REX, during the day of closest approaches to Pluto and Charon. Continuous tracking is not feasible as a result of pointing sharing with the instruments during the encounter phase. Needed radio tracking will be obtained during time slots shared with i) two-way Doppler tracking for navigation, ii) 'plasma rolls' with the spacecraft antenna pointing to Earth, and iii) during the ingress and egress phases of the occultations. Simulations of the NH encounter indicate the potential accuracies of the combined and individual mass determinations of Pluto and Charon in the order of 0.1%.

Determination of the System Mass and the Individual Masses of the Pluto System from New Horizons Radio Tracking

NASA Astrophysics Data System (ADS)

Hahn, Matthias; Pätzold, Martin; Andert, Tom; Bird, Michael K.; Tyler, Leonard G.; Linscott, Ivan; Hinson, Dave P.; Stern, Alan; Weaver, Hal; Olkin, Cathrin; Young, Leslie; Ennico, Kimberly

2015-11-01

One objective of the New Horizons Radio Science Experiment REX is the determination of the system mass and the individual masses of Pluto and Charon. About four weeks of two-way radio tracking centered around the closest approach of New Horizons to the Pluto system were processed. Major problems during the processing were caused by the small net forces of the spacecraft thruster activity, which produce extra Δv on the spacecraft motion superposed onto the continuously perturbed motion caused by the attracting forces of the Pluto system. The times of spacecraft thruster activity are known but the applied Δv needs to be specifically adjusted. No two-way tracking was available for the day of the flyby, but slots of REX one-way uplink tracking are used to cover the most important times near closest approach, e.g. during occultation entries and exits. This will help to separate the individual masses of Pluto and Charon from the system mass.

Mass Determination of Pluto and Charon from New Horizon REX Radio Science Observations

NASA Astrophysics Data System (ADS)

Pätzold, M.; Andert, T. P.; Tyler, G. L.; Bird, M. K.; Hinson, D. H.; Linscott, I. R.

2013-09-01

The anticipated 14 July 2015 New Horizons flythrough of the Pluto system provides the first opportunity to determine both the total system mass and the individual masses of Pluto and Charon by direct observation. This will be accomplished by use of: i) two-way Doppler radio frequency tracking data during intervals along the fly-in and -out trajectory, and ii) one-way uplink Doppler frequency recorded by the on-board radio science instrument, REX, during the day of closest approaches to Pluto and Charon. Continuous tracking is not feasible as a result of pointing sharing with the instruments during the encounter phase. Needed radio tracking will be obtained during time slots shared with i) two-way Doppler tracking for navigation, ii) 'plasma rolls' with the spacecraft antenna pointing to Earth, and iii) during the ingress and egress phases of the occultations. Simulations of the NH encounter indicate the potential accuracies of the combined and individual mass determinations of Pluto and Charon in the order of 0.1%.

New Horizons Sees Pluto (Animation) Note: There is debate within the science community as to whether

NASA Technical Reports Server (NTRS)

2007-01-01

The Long Range Reconnaissance Imager (LORRI) on New Horizons acquired images of the Pluto field three days apart in late September 2006, in order to see Pluto's motion against a dense background of stars. LORRI took three frames at 1-second exposures on both Sept. 21 and Sept. 24. Because it moved along its predicted path, Pluto was detected in all six images.

These images are displayed using false-color to represent different intensities: the lowest intensity level is black, different shades of red mark intermediate intensities, and the highest intensity is white.

The images appear pixilated because they were obtained in a mode that compensates for the drift in spacecraft pointing over long exposure times. LORRI also made these observations before operators uploaded new flight-control software in October; the upgraded software package includes an optical navigation capability that will make LORRI approximately three times more sensitive still than for these Pluto observations.

OSSOS. V. Diffusion in the Orbit of a High-perihelion Distant Solar System Object

NASA Astrophysics Data System (ADS)

Bannister, Michele T.; Shankman, Cory; Volk, Kathryn; Chen, Ying-Tung; Kaib, Nathan; Gladman, Brett J.; Jakubik, Marian; Kavelaars, J. J.; Fraser, Wesley C.; Schwamb, Megan E.; Petit, Jean-Marc; Wang, Shiang-Yu; Gwyn, Stephen D. J.; Alexandersen, Mike; Pike, Rosemary E.

2017-06-01

We report the discovery of the minor planet 2013 SY99 on an exceptionally distant, highly eccentric orbit. With a perihelion of 50.0 au, 2013 SY99’s orbit has a semimajor axis of 730 ± 40 au, the largest known for a high-perihelion trans-Neptunian object (TNO), and well beyond those of (90377) Sedna and 2012 VP113. Yet, with an aphelion of 1420 ± 90 au, 2013 SY99’s orbit is interior to the region influenced by Galactic tides. Such TNOs are not thought to be produced in the current known planetary architecture of the solar system, and they have informed the recent debate on the existence of a distant giant planet. Photometry from the Canada-France-Hawaii Telescope, Gemini North, and Subaru indicate 2013 SY99 is ˜250 km in diameter and moderately red in color, similar to other dynamically excited TNOs. Our dynamical simulations show that Neptune’s weak influence during 2013 SY99’s perihelia encounters drives diffusion in its semimajor axis of hundreds of astronomical units over 4 Gyr. The overall symmetry of random walks in the semimajor axis allows diffusion to populate 2013 SY99’s orbital parameter space from the 1000 to 2000 au inner fringe of the Oort cloud. Diffusion affects other known TNOs on orbits with perihelia of 45 to 49 au and semimajor axes beyond 250 au. This provides a formation mechanism that implies an extended population, gently cycling into and returning from the inner fringe of the Oort cloud.

Radio Thermal Emission from Pluto and Charon during the New Horizons Encounter

NASA Astrophysics Data System (ADS)

Bird, Michael; Linscott, Ivan; Hinson, David; Tyler, G. L.; Strobel, Darrell F.; New Horizons Science Team

2017-10-01

As part of the New Horizons Radio-Science Experiment REX, radio thermal emission from Pluto and Charon (wavelength: 4.2 cm) was observed during the encounter on 14 July 2015. The primary REX measurement, a determination of the atmospheric height profile from the surface up to about 100 km, was conducted during an uplink radio occultation at both ingress and egress (Hinson et al., Icarus 290, 96-111, 2017). During the interval between ingress and egress, when the Earth and the REX uplink signals were occulted by the Pluto disk, the spacecraft antenna continued to point toward Earth and thus scanned diametrically across the Pluto nightside. The average diameter of the HGA 3 dB beam was ≈1100 km at the surface during this opportunity, thereby providing crudely resolved measurements of the radio brightness temperature across Pluto. The best resolution for the REX radiometry observations occurred shortly after closest approach, when the HGA was scanned twice across Pluto. These observations will be reported elsewhere (Linscott et al., Icarus, submitted, 2017). In addition to the resolved observations, full disk brightness temperature measurements of both bodies were performed during the approach (dayside) and departure (nightside) phases of the encounter. We present the results of these observations and provide a preliminary interpretation of the measured brightness temperatures.

Pluto and Charon in False Color Show Compositional Diversity

NASA Image and Video Library

2015-07-14

This July 13, 2015, image of Pluto and Charon is presented in false colors to make differences in surface material and features easy to see. It was obtained by the Ralph instrument on NASA's New Horizons spacecraft, using three filters to obtain color information, which is exaggerated in the image. These are not the actual colors of Pluto and Charon, and the apparent distance between the two bodies has been reduced for this side-by-side view. The image reveals that the bright heart-shaped region of Pluto includes areas that differ in color characteristics. The western lobe, shaped like an ice-cream cone, appears peach color in this image. A mottled area on the right (east) appears bluish. Even within Pluto's northern polar cap, in the upper part of the image, various shades of yellow-orange indicate subtle compositional differences. The surface of Charon is viewed using the same exaggerated color. The red on the dark northern polar cap of Charon is attributed to hydrocarbon materials including a class of chemical compounds called tholins. The mottled colors at lower latitudes point to the diversity of terrains on Charon. This image was taken at 3:38 a.m. EDT on July 13, one day before New Horizons' closest approach to Pluto. http://photojournal.jpl.nasa.gov/catalog/PIA19707

New Details on Pluto

NASA Image and Video Library

2015-07-10

This image of Pluto was taken by New Horizons' Long Range Reconnaissance Imager (LORRI) at 4:18 UT on July 9, 2015, from a range of 3.9 million miles (6.3 million kilometers). It reveals new details on the surface of Pluto, including complex patterns in the transition between the very dark equatorial band (nicknamed "the whale"), which occupies the lower part of the image, and the brighter northern terrain. The bright arc at the bottom of the disk shows that there is more bright terrain beyond the southern margin of the "whale." The side of Pluto that will be studied in great detail during the close encounter on July 14 is now rotating off the visible disk on the right hand side, and will not be seen again until shortly before closest approach. Three consecutive images were combined and sharpened, using a process called deconvolution, to create this view. Deconvolution enhances real detail but can also generate spurious features, including the bright edge seen on the upper and left margins of the disk (though the bright margin on the bottom of the disk is real). The wireframe globe shows the orientation of Pluto in the image: thicker lines indicate the equator and the prime meridian (the direction facing Charon). Central longitude on Pluto is 86°. http://photojournal.jpl.nasa.gov/catalog/PIA19705

HABITABILITY OF EXOMOONS AT THE HILL OR TIDAL LOCKING RADIUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinkel, Natalie R.; Kane, Stephen R., E-mail: natalie.hinkel@gmail.com

2013-09-01

Moons orbiting extrasolar planets are the next class of object to be observed and characterized for possible habitability. Like the host-planets to their host-star, exomoons have a limiting radius at which they may be gravitationally bound, or the Hill radius. In addition, they also have a distance at which they will become tidally locked and therefore in synchronous rotation with the planet. We have examined the flux phase profile of a simulated, hypothetical moon orbiting at a distant radius around the confirmed exoplanets {mu} Ara b, HD 28185 b, BD +14 4559 b, and HD 73534 b. The irradiated fluxmore » on a moon at its furthest, stable distance from the planet achieves its largest flux gradient, which places a limit on the flux ranges expected for subsequent (observed) moons closer in orbit to the planet. We have also analyzed the effect of planetary eccentricity on the flux on the moon, examining planets that traverse the habitable zone either fully or partially during their orbit. Looking solely at the stellar contributions, we find that moons around planets that are totally within the habitable zone experience thermal equilibrium temperatures above the runaway greenhouse limit, requiring a small heat redistribution efficiency. In contrast, exomoons orbiting planets that only spend a fraction of their time within the habitable zone require a heat redistribution efficiency near 100% in order to achieve temperatures suitable for habitability. This means that a planet does not need to spend its entire orbit within the habitable zone in order for the exomoon to be habitable. Because the applied systems comprise giant planets around bright stars, we believe that the transit detection method is most likely to yield an exomoon discovery.« less

Tholins as Coloring Agents on Solar System Bodies

NASA Technical Reports Server (NTRS)

Cruikshank, D. P.; Ore, C. M. Dalle; Imanaka, H.

2004-01-01

Pre-biotic organic materials appear to be common on many small bodies in the outer Solar System, as evidenced by the color properties of these objects. We report on our continuing study of color properties in connection with the presence of complex organic solids (tholins) among the planets and their satellites, the asteroids, and the trans- Neptunian objects (Kuiper Belt objects). Most small, icy bodies in the Solar System, whether they have high or low surface reflectance (albedo), show a pronounced downward slope in reflectance at wavelengths shorter than approx. 1 micron. This increasing absorption of sunlight toward shorter wavelengths is characteristic of pi-bonds in hydrocarbons having chains or rings of conjugated C atoms. Tholins, which contain polycyclic aromatic and aliphatic hydrocarbons, exhibit these color properties. Using the complex refractive indices of tholins in models of the reflectance spectra of icy bodies in the Solar System, we find that these complex organic materials satisfactorily account for the coloration so widely observed. The new results presented here show that the wide variety of colors of Kuiper Belt objects can be fit very well with tholins, as can the colors of Pluto and Triton. The implications of these fits of Kuiper Belt objects is that complex organic material is created on their surfaces by energetic particle bombardment of native ices, and also may be accreted from external sources. In the cases of Pluto and Triton, photochemistry of their weak N2 + CH4 + CO atmospheres produces complex organic molecules that precipitate to the surface, providing local color.

Delayed Gratification Habitable Zones: When Deep Outer Solar System Regions Become Balmy During Post-Main Sequence Stellar Evolution

NASA Astrophysics Data System (ADS)

Stern, S. Alan

2003-06-01

Like all low- and moderate-mass stars, the Sun will burn as a red giant during its later evolution, generating of solar luminosities for some tens of millions of years. During this post-main sequence phase, the habitable (i.e., liquid water) thermal zone of our Solar System will lie in the region where Triton, Pluto-Charon, and Kuiper Belt objects orbit. Compared with the 1 AU habitable zone where Earth resides, this "delayed gratification habitable zone" (DGHZ) will enjoy a far less biologically hazardous environment - with lower harmful radiation levels from the Sun, and a far less destructive collisional environment. Objects like Triton, Pluto-Charon, and Kuiper Belt objects, which are known to be rich in both water and organics, will then become possible sites for biochemical and perhaps even biological evolution. The Kuiper Belt, with >105 objects >=50 km in radius and more than three times the combined surface area of the four terrestrial planets, provides numerous sites for possible evolution once the Sun's DGHZ reaches it. The Sun's DGHZ might be thought to only be of academic interest owing to its great separation from us in time. However, ~109 Milky Way stars burn as luminous red giants today. Thus, if icy-organic objects are common in the 20-50 AU zones of these stars, as they are in our Solar System (and as inferred in numerous main sequence stellar disk systems), then DGHZs may form a niche type of habitable zone that is likely to be numerically common in the Galaxy.