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Sample records for mercury planet

  1. Planet Mercury

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Mariner 10's first image of Mercury acquired on March 24, 1974. During its flight, Mariner 10's trajectory brought it behind the lighted hemisphere of Mercury, where this image was taken, in order to acquire important measurements with other instruments.

    This picture was acquired from a distance of 3,340,000 miles (5,380,000 km) from the surface of Mercury. The diameter of Mercury (3,031 miles; 4,878 km) is about 1/3 that of Earth.

    Images of Mercury were acquired in two steps, an inbound leg (images acquired before passing into Mercury's shadow) and an outbound leg (after exiting from Mercury's shadow). More than 2300 useful images of Mercury were taken, both moderate resolution (3-20 km/pixel) color and high resolution (better than 1 km/pixel) black and white coverage.

  2. Mercury: the forgotten planet.

    NASA Astrophysics Data System (ADS)

    Nelson, R. M.

    1997-11-01

    Mercury is the neglected child of the planetary system. Only one spacecraft has every ventured near it, whereas scores have probed the moon, Venus and Mars. The scant facts available show this strange, blazingly hot planet is full of surprises: its anomalous density and magnetic field suggest that Mercury may be where to seek clues to the origin of the solar system.

  3. The planet Mercury (1971)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The physical properties of the planet Mercury, its surface, and atmosphere are presented for space vehicle design criteria. The mass, dimensions, mean density, and orbital and rotational motions are described. The gravity field, magnetic field, electromagnetic radiation, and charged particles in the planet's orbit are discussed. Atmospheric pressure, temperature, and composition data are given along with the surface composition, soil mechanical properties, and topography, and the surface electromagnetic and temperature properties.

  4. Mercury - the hollow planet

    NASA Astrophysics Data System (ADS)

    Rothery, D. A.

    2012-04-01

    Mercury is turning out to be a planet characterized by various kinds of endogenous hole (discounting impact craters), which are compared here. These include volcanic vents and collapse features on horizontal scales of tens of km, and smaller scale depressions ('hollows') associated with bright crater-floor deposits (BCFD). The BCFD hollows are tens of metres deep and kilometres or less across and are characteristically flat-floored, with steep, scalloped walls. Their form suggests that they most likely result from removal of surface material by some kind of mass-wasting process, probably associated with volume-loss caused by removal (via sublimation?) of a volatile component. These do not appear to be primarily a result of undermining. Determining the composition of the high-albedo bluish surface coating in BCFDs will be a key goal for BepiColombo instruments such as MIXS (Mercury Imaging Xray Spectrometer). In contrast, collapse features are non-circular rimless pits, typically on crater floors (pit-floor craters), whose morphology suggests collapse into void spaces left by magma withdrawal. This could be by drainage of either erupted lava (or impact melt) or of shallowly-intruded magma. Unlike the much smaller-scale BCFD hollows, these 'collapse pit' features tend to lack extensive flat floors and instead tend to be close to triangular in cross-section with inward slopes near to the critical angle of repose. The different scale and morphology of BCFD hollows and collapse pits argues for quite different modes of origin. However, BCFD hollows adjacent to and within the collapse pit inside Scarlatti crater suggest that the volatile material whose loss was responsible for the growth of the hollows may have been emplaced in association with the magma whose drainage caused the main collapse. Another kind of volcanic collapse can be seen within a 25 km-wide volcanic vent outside the southern rim of the Caloris basin (22.5° N, 146.1° E), on a 28 m/pixel MDIS NAC image

  5. Venus and Mercury as Planets

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A general evolutionary history of the solar planetary system is given. The previously observed characteristics of Venus and Mercury (i.e. length of day, solar orbit, temperature) are discussed. The role of the Mariner 10 space probe in gathering scientific information on the two planets is briefly described.

  6. Thermal elastic deformations of the planet Mercury.

    NASA Technical Reports Server (NTRS)

    Liu, H.-S.

    1972-01-01

    The variation in solar heating due to the resonance rotation of Mercury produces periodic elastic deformations on the surface of the planet. The thermal stress and strain fields under Mercury's surface are calculated after certain simplifications. It is found that deformations penetrate to a greater depth than the variation of solar heating, and that the thermal strain on the surface of the planet pulsates with an amplitude of .004 and a period of 176 days.

  7. Thermal elastic deformations of the planet Mercury.

    NASA Technical Reports Server (NTRS)

    Liu, H.-S.

    1972-01-01

    The variation in solar heating due to the resonance rotation of Mercury produces periodic elastic deformations on the surface of the planet. The thermal stress and strain fields under Mercury's surface are calculated after certain simplifications. It is found that deformations penetrate to a greater depth than the variation of solar heating, and that the thermal strain on the surface of the planet pulsates with an amplitude of .004 and a period of 176 days.

  8. Thermal elastic deformations of the planet Mercury

    NASA Technical Reports Server (NTRS)

    Liu, H.

    1971-01-01

    The variation in solar heating due to the resonance rotation of Mercury produces periodic elastic deformations on the surface of the planet. The thermal stress and strain fields under Mercury's surface are calculated after certain simplifications. It is shown that deformations penetrate to a greater depth than the variation of solar heating, and that the thermal strain on the surface of the planet pulsates with an amplitude of 0.004 and a period of 176 days.

  9. Theory of Rotation for the Planet Mercury.

    PubMed

    Liu, H S; O'keefe, J A

    1965-12-24

    The theory of the rotation of the planet Mercury is developed in terms of the motion of a rigid system in an inverse-square field. It is possible for Mercury to rotate with a period exactly two-thirds of the period of revolution; there is a libration with a period of 25 years.

  10. Mercury: Exploration of a Planet

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The flight of the Mariner 10 spacecraft to Venus and Mercury is detailed in animation and photography. Views of Mercury are featured. Also included is animation on the origin of the solar system. Dr. Bruce C. Murray, director of the Jet Propulsion Laboratory, comments on the mission.

  11. Rotation of the planet mercury.

    PubMed

    Jefferys, W H

    1966-04-08

    The equations of motion for the rotation of Mercury are solved for the general case by an asymptotic expansion. The findings of Liu and O'Keefe, obtained by numerical integration of a special case, that it is possible for Mercury's rotation to be locked into a 2:3 resonance with its revolution, are confirmed in detail. The general solution has further applications.

  12. Mercury: Exploration of a Planet

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The flight of the Mariner 10 spacecraft to Venus and Mercury is detailed in animation and photography. Views of Mercury are featured. Also included is animation on the origin of the solar system. Dr. Bruce C. Murray, director of the Jet Propulsion Laboratory, comments on the mission.

  13. Physical properties of the planet Mercury

    NASA Technical Reports Server (NTRS)

    Clark, Pamela E.

    1988-01-01

    The global physical properties of Mercury are summarized with attention given to its figure and orbital parameters. The combination of properties suggests that Mercury has an extensive iron-rich core, possibly with a still-functioning dynamo, which is 42 percent of the interior by volume. Mercury's three major axes are comparable in size, indicating that the planet is a triaxial ellipsoid rather than an oblate spheroid. In terms of the domination of its surface by an intermediate plains terrane, it is more Venus- or Mars-like; however, due to the presence of a large metallic magnetic core, its interior may be more earth-like.

  14. Physical properties of the planet Mercury

    NASA Technical Reports Server (NTRS)

    Clark, Pamela E.

    1988-01-01

    The global physical properties of Mercury are summarized with attention given to its figure and orbital parameters. The combination of properties suggests that Mercury has an extensive iron-rich core, possibly with a still-functioning dynamo, which is 42 percent of the interior by volume. Mercury's three major axes are comparable in size, indicating that the planet is a triaxial ellipsoid rather than an oblate spheroid. In terms of the domination of its surface by an intermediate plains terrane, it is more Venus- or Mars-like; however, due to the presence of a large metallic magnetic core, its interior may be more earth-like.

  15. Sputtering of sodium on the planet Mercury

    NASA Technical Reports Server (NTRS)

    Mcgrath, M. A.; Johnson, R. E.; Lanzerotti, L. J.

    1986-01-01

    It is shown here that ion sputtering cannot account for the observed neutral sodium vapor column density on Mercury, but that it is an important loss mechanism for Na. Photons are likely to be the dominant stimulus, both directly through photodesorption and indirectly through thermal desorption of absorbed Na. It is concluded that the atmosphere produced is characterized by the planet's surface temperature, with the ion-sputtered Na contributing to a lesser, but more extended, component of the atmosphere.

  16. Sputtering of sodium on the planet Mercury

    NASA Technical Reports Server (NTRS)

    Mcgrath, M. A.; Johnson, R. E.; Lanzerotti, L. J.

    1986-01-01

    It is shown here that ion sputtering cannot account for the observed neutral sodium vapor column density on Mercury, but that it is an important loss mechanism for Na. Photons are likely to be the dominant stimulus, both directly through photodesorption and indirectly through thermal desorption of absorbed Na. It is concluded that the atmosphere produced is characterized by the planet's surface temperature, with the ion-sputtered Na contributing to a lesser, but more extended, component of the atmosphere.

  17. Earth-type planets (Mercury, Venus, and Mars)

    NASA Technical Reports Server (NTRS)

    Marov, M. Y.; Davydov, V. D.

    1975-01-01

    Spacecraft- and Earth-based studies on the physical nature of the planets Mercury, Venus, and Mars are reported. Charts and graphs are presented on planetary surface properties, rotational parameters, atmospheric compositions, and astronomical characteristics.

  18. Earth-type planets (Mercury, Venus, and Mars)

    NASA Technical Reports Server (NTRS)

    Marov, M. Y.; Davydov, V. D.

    1975-01-01

    Spacecraft- and Earth-based studies on the physical nature of the planets Mercury, Venus, and Mars are reported. Charts and graphs are presented on planetary surface properties, rotational parameters, atmospheric compositions, and astronomical characteristics.

  19. Earthlike planets: Surfaces of Mercury, Venus, earth, moon, Mars

    NASA Technical Reports Server (NTRS)

    Murray, B.; Malin, M. C.; Greeley, R.

    1981-01-01

    The surfaces of the earth and the other terrestrial planets of the inner solar system are reviewed in light of the results of recent planetary explorations. Past and current views of the origin of the earth, moon, Mercury, Venus and Mars are discussed, and the surface features characteristic of the moon, Mercury, Mars and Venus are outlined. Mechanisms for the modification of planetary surfaces by external factors and from within the planet are examined, including surface cycles, meteoritic impact, gravity, wind, plate tectonics, volcanism and crustal deformation. The origin and evolution of the moon are discussed on the basis of the Apollo results, and current knowledge of Mercury and Mars is examined in detail. Finally, the middle periods in the history of the terrestrial planets are compared, and future prospects for the exploration of the inner planets as well as other rocky bodies in the solar system are discussed.

  20. Earthlike planets: Surfaces of Mercury, Venus, earth, moon, Mars

    NASA Technical Reports Server (NTRS)

    Murray, B.; Malin, M. C.; Greeley, R.

    1981-01-01

    The surfaces of the earth and the other terrestrial planets of the inner solar system are reviewed in light of the results of recent planetary explorations. Past and current views of the origin of the earth, moon, Mercury, Venus and Mars are discussed, and the surface features characteristic of the moon, Mercury, Mars and Venus are outlined. Mechanisms for the modification of planetary surfaces by external factors and from within the planet are examined, including surface cycles, meteoritic impact, gravity, wind, plate tectonics, volcanism and crustal deformation. The origin and evolution of the moon are discussed on the basis of the Apollo results, and current knowledge of Mercury and Mars is examined in detail. Finally, the middle periods in the history of the terrestrial planets are compared, and future prospects for the exploration of the inner planets as well as other rocky bodies in the solar system are discussed.

  1. Terrestrial Planet Formation: Constraining the Formation of Mercury

    NASA Astrophysics Data System (ADS)

    Lykawka, Patryk Sofia; Ito, Takashi

    2017-04-01

    How the four terrestrial planets of the solar system formed is one of the most fundamental questions in the planetary sciences. Particularly, the formation of Mercury remains poorly understood. We investigated terrestrial planet formation by performing 110 high-resolution N-body simulation runs using more than 100 embryos and 6000 disk planetesimals representing a primordial protoplanetary disk. To investigate the formation of Mercury, these simulations considered an inner region of the disk at 0.2–0.5 au (the Mercury region) and disks with and without mass enhancements beyond the ice line location, a IL, in the disk, where a IL = 1.5, 2.25, and 3.0 au were tested. Although Venus and Earth analogs (considering both orbits and masses) successfully formed in the majority of the runs, Mercury analogs were obtained in only nine runs. Mars analogs were also similarly scarce. Our Mercury analogs concentrated at orbits with a ∼ 0.27–0.34 au, relatively small eccentricities/inclinations, and median mass m ∼ 0.2 {M}\\oplus . In addition, we found that our Mercury analogs acquired most of their final masses from embryos/planetesimals initially located between 0.2 and ∼1–1.5 au within 10 Myr, while the remaining mass came from a wider region up to ∼3 au at later times. Although the ice line was negligible in the formation of planets located in the Mercury region, it enriched all terrestrial planets with water. Indeed, Mercury analogs showed a wide range of water mass fractions at the end of terrestrial planet formation.

  2. Mercury Mapper: First Look at the Innermost Planet

    NASA Astrophysics Data System (ADS)

    Hirshon, B.

    2012-12-01

    Until very recently little has been known about the planet Mercury, despite its relative proximity to Earth. Mercury is difficult to observe from Earth, because it is so small and so close to the sun, and only one spacecraft had visited the planet: Mariner 10, in the mid 1970s. But now, the MESSENGER spacecraft is in orbit around Mercury, sending back high-resolution images of virtually the entire planetary surface. This provides a rare opportunity for public engagement in the exploration of a new world—a chance for non-scientists to help scientists locate, measure and describe terrain never before seen. Mercury Mapper, designed by CosmoQuest, will provide the training and toolkit needed to accomplish the task. Using thousands of images selected by the MESSENGER science team, Mercury Mapper will guide citizen scientists through the process of finding, categorizing and measuring key topographic features of interest to researchers. Mercury Mapper users will in many cases be the first people to examine these features. In this session, members of the MESSENGER Education and Public Outreach team along with CosmoQuest designers involved in developing Mercury Mapper will share the many considerations and tradeoffs involved in creating a fun environment for engaging the public while also serving the interests of scientists performing original research.; ;

  3. Surface history of Mercury - Implications for terrestrial planets

    NASA Technical Reports Server (NTRS)

    Murray, B. C.; Strom, R. G.; Trask, N. J.; Gault, D. E.

    1975-01-01

    A plausible surface history of Mercury is presented which is suggested by Mariner 10 television pictures. Five periods are postulated which are delineated by successive variations in the modification of the surface by external and internal processes: accretion and differentiation, terminal heavy bombardment, formation of the Caloris basin, flooding of that basin and other areas, and light cratering accumulated on the smooth plains. Each period is described in detail; the overall history is compared with the surface histories of Venus, Mars, and the moon; and the implications of this history for earth are discussed. It is tentatively concluded that: Mercury is a differentiated planet most likely composed of a large iron core enclosed by a relatively thin silicate layer; heavy surface bombardment occurred about four billion years ago, which probably affected all the inner planets, and was followed by a period of volcanic activity; no surface modifications caused by tectonic, volcanic, or atmospheric processes took place after the volcanic period.

  4. Surface history of Mercury - Implications for terrestrial planets

    NASA Technical Reports Server (NTRS)

    Murray, B. C.; Strom, R. G.; Trask, N. J.; Gault, D. E.

    1975-01-01

    A plausible surface history of Mercury is presented which is suggested by Mariner 10 television pictures. Five periods are postulated which are delineated by successive variations in the modification of the surface by external and internal processes: accretion and differentiation, terminal heavy bombardment, formation of the Caloris basin, flooding of that basin and other areas, and light cratering accumulated on the smooth plains. Each period is described in detail; the overall history is compared with the surface histories of Venus, Mars, and the moon; and the implications of this history for earth are discussed. It is tentatively concluded that: Mercury is a differentiated planet most likely composed of a large iron core enclosed by a relatively thin silicate layer; heavy surface bombardment occurred about four billion years ago, which probably affected all the inner planets, and was followed by a period of volcanic activity; no surface modifications caused by tectonic, volcanic, or atmospheric processes took place after the volcanic period.

  5. Reference surfaces of the planet Mercury from MESSENGER

    NASA Astrophysics Data System (ADS)

    Karimi, Roohollah; Ardalan, Alireza A.; Farahani, Soheil Vasheghani

    2016-01-01

    The aim of this work is to study the reference surfaces of the planet Mercury obtained by the MESSENGER mission in order to provide a geodetic reference system (GRS) for the planet. The reference surfaces under consideration are the geoid and the reference ellipsoid. The reference ellipsoid is a triaxial planetocentric equipotential ellipsoid that best fits the geoid. To determine the reference surfaces, two methods are presented. In this line, the shape of the planet is sampled by expanding the global shape model (GSM) GTMES_125V03_SHA only up to the degree strength of the global gravity model (GGM) GGMES_50V06_SHA. The spatial resolution of the sampling points is selected based on the degree strength and the latitude of the location. According to our preferred method, we estimate the values for the semi-major equatorial axis, semi-minor equatorial axis, and polar axis of the reference ellipsoid equal to 2, 439, 422 ± 368m , 2, 439, 304 ± 368m , and 2, 439, 178 ± 368m , respectively. Moreover, we estimate the geoid potential value equal to 9, 032, 044 ± 1361m2 /s2 . The three axes of the reference ellipsoid give the polar and equatorial flattenings equal to (100 ± 213) ×10-6 and (48 ± 213) ×10-6 , respectively. However, we show that the best-fitting ellipsoid gives the polar and equatorial flattenings equal to (896 ± 213) ×10-6 and (426 ± 213) ×10-6 , respectively. The best-fitting ellipsoid is a triaxial ellipsoid that fits the shape of Mercury in a least-squares sense. The significant discrepancy observed between the flattenings of the two ellipsoids is a consequence of Mercury's geophysical characteristics together with its non-hydrostatic equilibrium. The results provided in the present work prove adequate for defining a promised GRS for the planet Mercury.

  6. Google Mercury: The Launch of a New Planet

    NASA Astrophysics Data System (ADS)

    Hirshon, B.; Chapman, C. R.; Edmonds, J.; Goldstein, J.; Hallau, K. G.; Solomon, S. C.; Vanhala, H.; Weir, H. M.; Messenger Education; Public Outreach Epo Team

    2010-12-01

    The NASA MESSENGER mission’s Education and Public Outreach (EPO) Team, in cooperation with Google, Inc., has launched Google Mercury, an immersive new environment on the Google Earth platform. Google Mercury features hundreds of surface features, most of them newly revealed by the three flybys of the innermost planet by the MESSENGER spacecraft. As with Google Earth, Google Mercury is available on line at no cost. This presentation will demonstrate how our team worked with Google staff, features we incorporated, how games can be developed within the Google Earth platform, and how others can add tours, games, and other educational features. Finally, we will detail new enhancements to be added once MESSENGER enters into orbit about Mercury in March 2011 and begins sending back compelling images and other global data sets on a daily basis. The MESSENGER EPO Team comprises individuals from the American Association for the Advancement of Science (AAAS); Carnegie Academy for Science Education (CASE); Center for Educational Resources (CERES) at Montana State University (MSU) - Bozeman; National Center for Earth and Space Science Education (NCESSE); Johns Hopkins University Applied Physics Laboratory (JHU/APL); National Air and Space Museum (NASM); Science Systems and Applications, Inc. (SSAI); and Southwest Research Institute (SwRI). Screen shot of Google Mercury as a work in progress

  7. ISA accelerometer: fundamental support for the exploration of planet Mercury

    NASA Astrophysics Data System (ADS)

    Iafolla, Valerio; Fiorenza, Emiliano; Lefevre, Carlo; Nozzoli, Sergio; Peron, Roberto; Reale, Andrea; Santoli, Francesco

    2010-05-01

    The development of BepiColombo mission is proceeding, in view of the launch, foreseen for 2014. This mission will perform a thorough study of the planet Mercury and its environment. An important set of scientific objectives is constituted by the so-called Radio Science Experiments (RSE), which will study the gravitational field and rotation of the planet, and will perform very precise tests of general relativity theory. In order to reach the required level of accuracy in recovering the relevant parameters, the data coming from the high-sensitivity ISA (Italian Spring Accelerometer) instrument onboard the Mercury Planetary Orbiter (MPO) will be used: this will be the first time for a deep-space probe. Following a brief description of the mission and RSE, the instrument and its wide capabilities will be reviewed. The focus will be in particular on the updated error budget, operational procedures and extended use of the instrument in the various parts of the RSE. It will be also described the procedure for on-ground calibration of the accelerometer.

  8. Highly Reducing Partitioning Experiments Relevant to the Planet Mercury

    NASA Technical Reports Server (NTRS)

    Rowland, Rick, II; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Danielson, Lisa R.

    2017-01-01

    With the data returned from the MErcury Surface Space ENvironment GEochemistry and Ranging (MESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition. The high S and low FeO contents observed from MESSENGER on the planet's surface suggests a low oxygen fugacity of the present planetary materials. Estimates of the oxygen fugacity for Mercurian magmas are approximately 3-7 log units below the Iron-Wüstite (Fe-FeO) oxygen buffer, several orders of magnitude more reducing than other terrestrial bodies we have data from such as the Earth, Moon, or Mars. Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions are available in our collections (e.g., enstatite chondrites, achondrites, aubrites). With this limited amount of material, we must perform experiments to determine the elemental partitioning behavior of typically lithophile elements as a function of decreasing oxygen fugacity. Experiments are being conducted at 4 GPa in an 880-ton multi-anvil press, at temperatures up to 1850degC. The composition of starting materials for the experiments were selected for the final run products to contain metal, silicate melt, and sulfide melt phases. Oxygen fugacity is controlled in the experiments by adding silicon metal to the samples, using the Si-SiO2 oxygen buffer, which is approximately 5 log units more reducing than the Fe-FeO oxygen buffer at our temperatures of interest. The target silicate melt compositional is diopside (CaMgSi2O6) because measured surface compositions indicate partial melting of a pyroxene-rich mantle. Elements detected on Mercury

  9. Mercury-like Planets: Separating Metals and Silicates by Photophoresis

    NASA Astrophysics Data System (ADS)

    Wurm, Gerhard; Trieloff, M.; Rauer, H.; Kuepper, M.

    2013-10-01

    Particles at the inner edge of protoplanetary disks are embedded in gas and are illuminated by starlight. This leads to photophoretic forces which - acting best on low thermal conductivity particles - push silicates outward. Metal grains remain behind and get separated from the silicates. If planetesimal formation is set on top of this separation an outward migrating edge will naturally lead to a metal-silicate gradient. Metal rich bodies like Mercury will form close to the star and metal poor bodies will be located further outward. This is consistent with chondrites being mostly metal poor and it is consistent with the smallest rocky planets CoRoT-7b and Kepler-10b - found close to their host star - being Mercury-like. In contrast to high temperature processing photophoresis does not change the abundance of volatile elements. We started to model the particle transport in the transition region between the optical thin disk gap and the optical thick outer protoplanetary disk. Also, first drop tower experiments have been carried out to quantify the strength of the photophoretic force on silicate grains.

  10. Observations at the planet Mercury by the plasma electron experiment, Mariner 10

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Scudder, J. D.; Vasyliunas, V. M.; Hartle, R. E.; Siscoe, G. L.

    1976-01-01

    Plasma electron observations made onboard Mariner 10 are reported. Three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the Earth but much smaller in relation to the size of the planet. Electron populations similar to those found in the Earth's magnetotail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the Earth. The magnetosphere of Mercury resembles to a marked degree a reduced version of that of the Earth, with no significant differences of structure.

  11. Circular polarization of light by planet Mercury and enantiomorphism of its surface minerals.

    PubMed

    Meierhenrich, Uwe J; Thiemann, Wolfram H P; Barbier, Bernard; Brack, André; Alcaraz, Christian; Nahon, Laurent; Wolstencroft, Ray

    2002-04-01

    Different mechanisms for the generation of circular polarization by the surface of planets and satellites are described. The observed values for Venus, the Moon, Mars, and Jupiter obtained by photo-polarimetric measurements with Earth based telescopes, showed accordance with theory. However, for planet Mercury asymmetric parameters in the circular polarization were measured that do not fit with calculations. For BepiColombo, the ESA cornerstone mission 5 to Mercury, we propose to investigate this phenomenon using a concept which includes two instruments. The first instrument is a high-resolution optical polarimeter, capable to determine and map the circular polarization by remote scanning of Mercury's surface from the Mercury Planetary Orbiter MPO. The second instrument is an in situ sensor for the detection of the enantiomorphism of surface crystals and minerals, proposed to be included in the Mercury Lander MSE.

  12. MESSENGER, MErcury: Surface, Space ENvironment, GEochemistry, and Ranging; A Mission to Orbit and Explore the Planet Mercury

    NASA Technical Reports Server (NTRS)

    1999-01-01

    MESSENGER is a scientific mission to Mercury. Understanding this extraordinary planet and the forces that have shaped it is fundamental to understanding the processes that have governed the formation, evolution, and dynamics of the terrestrial planets. MESSENGER is a MErcury Surface, Space ENvironment, GEochemistry and Ranging mission to orbit Mercury for one Earth year after completing two flybys of that planet following two flybys of Venus. The necessary flybys return significant new data early in the mission, while the orbital phase, guided by the flyby data, enables a focused scientific investigation of this least-studied terrestrial planet. Answers to key questions about Mercury's high density, crustal composition and structure, volcanic history, core structure, magnetic field generation, polar deposits, exosphere, overall volatile inventory, and magnetosphere are provided by an optimized set of miniaturized space instruments. Our goal is to gain new insight into the formation and evolution of the solar system, including Earth. By traveling to the inner edge of the solar system and exploring a poorly known world, MESSENGER fulfills this quest.

  13. MESSENGER Measurements of Radioactive Elements on Mercury: Implications for the Planet's Formation and Evolution

    NASA Astrophysics Data System (ADS)

    Evans, L. G.; Peplowski, P. N.; Hauck, S. A.; McCoy, T. J.; Boynton, W. V.; Ebel, D. S.; Goldsten, J. O.; Hamara, D. K.; Lawrence, D. J.; McNutt, R. L.; Rhodes, E. A.; Nittler, L. R.; Sprague, A. L.; Solomon, S. C.; Starr, R. D.

    2011-12-01

    Measurements of the surface composition of Mercury offers a window into the epoch of planet formation in the inner solar system. Mercury likely preserves a more complete record of early crustal formation than do Venus, Earth, or Mars, each of which experienced extensive and prolonged resurfacing and near-surface alteration since earliest crustal formation. The MErcury Surface, Space ENvironment, GEochemisty, and Ranging (MESSENGER) spacecraft was inserted into Mercury orbit on 18 March 2011 and carries a suite of instruments designed for remote sensing of elemental and mineralogical composition including a Gamma-Ray Spectrometer (GRS). We report measured surface abundances of radioactive elements on Mercury and their implications for hypotheses regarding the planet's formation and thermal evolution. The average surface abundances of radioactive elements over the region of Mercury measured by the GRS are 1150 ± 220 ppm K, 220 ± 60 ppb Th, and 90 ± 20 ppb U. Ratios of the moderately volatile incompatible element K to the refractory incompatible elements Th and U provide insights into the volatile inventory of planetary bodies. The measured K/Th ratio for Mercury (5200 ± 1800) is comparable to values for the other terrestrial planets. By contrast, the lunar K/Th value (360) is an order of magnitude lower, indicative of the depletion of lunar volatiles relative to Earth. Mercury's K/Th ratio, combined with the high abundance of the volatile element sulfur measured by the MESSENGER X-Ray Spectrometer, indicates that the planet has a volatile inventory similar to those of the other terrestrial planets. Hypotheses proposed to explain the unusually high ratio of metal to silicate on Mercury also carry predictions for the ratios of volatile to refractory elements that can be tested against the K, Th, and U abundances measured by MESSENGER. The abundance of K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme

  14. Imaging the Sources and Full Extent of the Sodium Tail of the Planet Mercury

    NASA Technical Reports Server (NTRS)

    Baumgardner, Jeffrey; Wilson, Jody; Mendillo, Michael

    2008-01-01

    Observations of sodium emission from Mercury can be used to describe the spatial and temporal patterns of sources and sinks in the planet s surface-boundary-exosphere. We report on new data sets that provide the highest spatial resolution of source regions at polar latitudes, as well as the extraordinary length of a tail of escaping Na atoms. The tail s extent of approx.1.5 degrees (nearly 1400 Mercury radii) is driven by radiation pressure effects upon Na atoms sputtered from the surface in the previous approx.5 hours. Wide-angle filtered-imaging instruments are thus capable of studying the time history of sputtering processes of sodium and other species at Mercury from ground-based observatories in concert with upcoming satellite missions to the planet. Plasma tails produced by photo-ionization of Na and other gases in Mercury s neutral tails may be observable by in-situ instruments.

  15. Imaging the Sources and Full Extent of the Sodium Tail of the Planet Mercury

    NASA Technical Reports Server (NTRS)

    Baumgardner, Jeffrey; Wilson, Jody; Mendillo, Michael

    2008-01-01

    Observations of sodium emission from Mercury can be used to describe the spatial and temporal patterns of sources and sinks in the planet s surface-boundary-exosphere. We report on new data sets that provide the highest spatial resolution of source regions at polar latitudes, as well as the extraordinary length of a tail of escaping Na atoms. The tail s extent of approx.1.5 degrees (nearly 1400 Mercury radii) is driven by radiation pressure effects upon Na atoms sputtered from the surface in the previous approx.5 hours. Wide-angle filtered-imaging instruments are thus capable of studying the time history of sputtering processes of sodium and other species at Mercury from ground-based observatories in concert with upcoming satellite missions to the planet. Plasma tails produced by photo-ionization of Na and other gases in Mercury s neutral tails may be observable by in-situ instruments.

  16. Radio-interferometric imaging of the subsurface emissions from the planet Mercury

    NASA Technical Reports Server (NTRS)

    Burns, J. O.; Zeilik, M.; Gisler, G. R.; Borovsky, J. E.; Baker, D. N.

    1987-01-01

    The distribution of total and polarized intensities from Mercury's subsurface layers have been mapped using VLA observations. The first detection of a hot pole along the Hermean equator is reported and modeled as black-body reradiation from preferential diurnal heating. These observations appear to rule out any internal sources of heat within Mercury. Polarized emission from the limb of the planet is also found, and is understood in terms of the dielectric properties of the Hermean surface.

  17. Rotation of mercury: theoretical analysis of the dynamics of a rigid ellipsoidal planet.

    PubMed

    Laslett, L J; Sessler, A M

    1966-03-18

    The second-order nonlinear differential equation for the rotation of Mercury implies locked-in motion when the period is within the range where e is the eccentricity and T is the period of Mercury's orbit, the time t is measured from perihelion, and lambda is a measure of the planet's disiortion. For values near 2T/3, the instantaneous period oscillates about 2T/3 with period (21lambdae/2)T.

  18. Radio-interferometric imaging of the subsurface emissions from the planet Mercury

    NASA Technical Reports Server (NTRS)

    Burns, J. O.; Zeilik, M.; Gisler, G. R.; Borovsky, J. E.; Baker, D. N.

    1987-01-01

    The distribution of total and polarized intensities from Mercury's subsurface layers have been mapped using VLA observations. The first detection of a hot pole along the Hermean equator is reported and modeled as black-body reradiation from preferential diurnal heating. These observations appear to rule out any internal sources of heat within Mercury. Polarized emission from the limb of the planet is also found, and is understood in terms of the dielectric properties of the Hermean surface.

  19. Observations at the planet Mercury by the plasma electron experiment - Mariner 10

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Scudder, J. D.; Vasyliunas, V. M.; Hartle, R. E.; Siscoe, G. L.

    1977-01-01

    Two nightside encounters with Mercury's magnetosphere by Mariner 10 revealed bow shock and magnetosheath signatures in the plasma electron data that are entirely consistent with the geometry expected for an interaction between a planet-centered magnetic dipole and the solar wind. The geometrically determined distance between the planet's center and the solar wind stagnation point is 1.4 plus or minus 0.1 R sub M. Both diffuse and sharp shock crossings were observed on the two magnetosphere encounters.

  20. Observations at the planet Mercury by the plasma electron experiment - Mariner 10

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Scudder, J. D.; Vasyliunas, V. M.; Hartle, R. E.; Siscoe, G. L.

    1977-01-01

    Two nightside encounters with Mercury's magnetosphere by Mariner 10 revealed bow shock and magnetosheath signatures in the plasma electron data that are entirely consistent with the geometry expected for an interaction between a planet-centered magnetic dipole and the solar wind. The geometrically determined distance between the planet's center and the solar wind stagnation point is 1.4 plus or minus 0.1 R sub M. Both diffuse and sharp shock crossings were observed on the two magnetosphere encounters.

  1. IAU nomenclature for albedo features on the planet Mercury

    NASA Technical Reports Server (NTRS)

    Dollfus, A.; Chapman, C. R.; Davies, M. E.; Gingerich, O.; Goldstein, R.; Guest, J.; Morrison, D.; Smith, B. A.

    1978-01-01

    The International Astronomical Union has endorsed a nomenclature for the albedo features on Mercury. Designations are based upon the mythological names related to the god Hermes; they are expressed in Latin form. The dark-hued albedo features are associated with the generic term Solitudo. The light-hued areas are designated by a single name without generic term. The 32 names adopted are allocated on the Mercury map.

  2. Improving the Visual Magnitudes of the Planets in The Astronomical Almanac. I. Mercury and Venus

    DTIC Science & Technology

    2005-01-01

    2005 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Improving the Visual Magnitudes of the Planets in The Astronomical Almanac...1. Mercury and Venus 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK

  3. Groundbased High-Definition Imaging of the Planet Mercury

    NASA Astrophysics Data System (ADS)

    Mendillo, M.; Baumgardner, J.; Wilson, J. K.

    2000-10-01

    New instrumentation has been developed for spectral imaging of Mercury's extended atmosphere. The approach depends upon simultaneous short-exposure images in white light and sodium, with the former used to select the frames for post-integration of the sodium images. The effects of atmospheric seeing are thus minimized by the combination of high-speed exposures and subsequent selective integration. The instrumentation consists of a long slit imaging Echelle spectrometer equipped with an image slicer and an imaging photon detector. A test of the white light component of the technique has yielded a best-to-date image of a portion of Mercury's surface not photographed during the Mariner 10 mission. The pilot observations were made at the Mt. Wilson Observatory on 29 August 1998. The optical images show Mercury's albedo features over the longitude range 270o-360o W. Spatially variable features are seen with a resolution of ~250 km. A bright feature in the northern hemisphere appears similar to the lunar crater Copernicus; three darker features are similar in appearance to lunar maria. There are no obvious relations of the white light albedo features to either radar maps or sodium bright spots reported in the literature.

  4. The use of radar and visual observations to characterize the surface structure of the planet Mercury

    NASA Technical Reports Server (NTRS)

    Clark, P. E.; Kobrick, M.; Jurgens, R. F.

    1985-01-01

    An analysis is conducted of available topographic profiles and scattering parameters derived from earth-based S- and X-band radar observations of Mercury, in order to determine the nature and origin of regional surface variations and structures that are typical of the planet. Attention is given to the proposal that intercrater plains on Mercury formed from extensive volcanic flooding during bombardment, so that most craters were formed on a partially molten surface and were thus obliterated, together with previously formed tectonic features.

  5. The use of radar and visual observations to characterize the surface structure of the planet Mercury

    NASA Technical Reports Server (NTRS)

    Clark, P. E.; Kobrick, M.; Jurgens, R. F.

    1985-01-01

    An analysis is conducted of available topographic profiles and scattering parameters derived from earth-based S- and X-band radar observations of Mercury, in order to determine the nature and origin of regional surface variations and structures that are typical of the planet. Attention is given to the proposal that intercrater plains on Mercury formed from extensive volcanic flooding during bombardment, so that most craters were formed on a partially molten surface and were thus obliterated, together with previously formed tectonic features.

  6. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Thermal models of Mercury. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Recent and more complex thermal models of Mercury and the terrestrial planets are discussed or noted. These models isolate a particular aspect of the planet's thermal history in an attempt to understand that parameter. Among these topics are thermal conductivity, convection, radiogenic sources of heat, other heat sources, and the problem of the molten core and regenerative dynamo.

  7. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Thermal models of Mercury. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Recent and more complex thermal models of Mercury and the terrestrial planets are discussed or noted. These models isolate a particular aspect of the planet's thermal history in an attempt to understand that parameter. Among these topics are thermal conductivity, convection, radiogenic sources of heat, other heat sources, and the problem of the molten core and regenerative dynamo.

  8. Exo-Mercury Analogues and the Roche Limit for Close-Orbiting Rocky Planets

    NASA Astrophysics Data System (ADS)

    Rogers, Leslie A.; Price, Ellen

    2015-12-01

    The origin of Mercury's enhanced iron content is a matter of ongoing debate. The characterization of rocky exoplanets promises to provide new independent insights on this topic, by constraining the occurrence rate and physical and orbital properties of iron-enhanced planets orbiting distant stars. The ultra-short-period transiting planet candidate KOI-1843.03 (0.6 Earth-radius, 4.245 hour orbital period, 0.46 Solar-mass host star) represents the first exo-Mercury planet candidate ever identified. For KOI-1843.03 to have avoided tidal disruption on such a short orbit, Rappaport et al. (2013) estimate that it must have a mean density of at least 7g/cc and be at least as iron rich as Mercury. This density lower-limit, however, relies upon interpolating the Roche limits of single-component polytrope models, which do not accurately capture the density profiles of >1000 km differentiated rocky bodies. A more exact calculation of the Roche limit for the case of rocky planets of arbitrary composition and central concentration is needed. We present 3D interior structure simulations of ultra-short-period tidally distorted rocky exoplanets, calculated using a modified version of Hachisu’s self-consistent field method and realistic equations of state for silicates and iron. We derive the Roche limits of rocky planets as a function of mass and composition, and refine the composition constraints on KOI-1843.03. We conclude by discussing the implications of our simulations for the eventual characterization of short-period transiting planets discovered by K2, TESS, CHEOPS and PLATO.

  9. Mercury: Informing Remote Sensing through Petrology in the Absence of Samples from the Innermost Planet

    NASA Astrophysics Data System (ADS)

    McCoy, T. J.; Nittler, L. R.; Stockstill-Cahill, K.; Blewett, D. T.

    2012-12-01

    Remote sensing missions and petrologic studies are complementary methods of understanding airless planetary bodies. For bodies with both orbital missions and samples available for laboratory study, missions provide global chemical, mineralogical, and geologic data sets and context for samples, whereas samples often provide complementary petrogenetic histories in a chronological framework. In contrast, although the wealth of orbital data from MESSENGER is not complemented by samples from Mercury, petrologic and experimental studies remain essential to understanding the innermost planet. Prior to MESSENGER, most models centered on high-temperature events and formation under highly reducing conditions to explain Mercury's high metal to silicate ratio. These models predicted enrichment in refractory elements and depletion in volatile elements. The inference of formation at highly reducing conditions is supported by MESSENGER results. The low FeO concentration in the crust, implied low FeO contents of the mantle, apparent efficient partitioning of iron into the core, and evidence for Ca- and/or Mg-sulfides from X-Ray Spectrometer data are all consistent with reducing conditions. In contrast, the suggestion that Mercury is highly volatile-depleted has been refuted. Direct evidence for a relatively volatile-rich planet come from Na, K, and S abundances measured on the surface with MESSENGER's XRS and Gamma-Ray Spectrometer and the presence of neutral and ionized Na, K, and S species in the exosphere. Indirect evidence for volatile-rich compositions include the suggestion of volcanic vents with associated mantling pyroclastic deposits, hollows inferred to form by geologically recent volatile loss, and an inferred interior structure that includes a solid iron sulfide layer at the top of Mercury's fluid core. Petrologic and experimental studies of meteorites have played a key role in deciphering orbital data from MESSENGER. Partial melts from an enstatite chondrite

  10. A whole new Mercury: MESSENGER reveals a dynamic planet at the last frontier of the inner solar system

    NASA Astrophysics Data System (ADS)

    Johnson, Catherine L.; Hauck, , Steven A.

    2016-11-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission yielded a wealth of information about the innermost planet. For the first time, visible images of the entire planet, absolute altimetry measurements and a global gravity field, measurements of Mercury's surface composition, magnetic field, exosphere, and magnetosphere taken over more than four Earth years are available. From these data, two overarching themes emerge. First, multiple data sets and modeling efforts point toward a dynamic ancient history. Signatures of graphite in the crust suggest solidification of an early magma ocean, image data show extensive volcanism and tectonic features indicative of subsequent global contraction, and low-altitude measurements of magnetic fields reveal an ancient magnetic field. Second, the present-day Mercury environment is far from quiescent. Convective motions in the outer core support a modern magnetic field whose strength and geometry are unique among planets with global magnetic fields. Furthermore, periodic and aperiodic variations in the magnetosphere and exosphere have been observed, some of which couple to the surface and the planet's deep interior. Finally, signatures of geologically recent volatile activity at the surface have been detected. Mercury's early history and its present-day environment have common elements with the other inner solar system bodies. However, in each case there are also crucial differences and these likely hold the key to further understanding of Mercury and terrestrial planet evolution. MESSENGER's exploration of Mercury has enabled a new view of the innermost planet, and more importantly has set the stage for much-needed future exploration.

  11. Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution.

    PubMed

    Peplowski, Patrick N; Evans, Larry G; Hauck, Steven A; McCoy, Timothy J; Boynton, William V; Gillis-Davis, Jeffery J; Ebel, Denton S; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Nittler, Larry R; Solomon, Sean C; Rhodes, Edgar A; Sprague, Ann L; Starr, Richard D; Stockstill-Cahill, Karen R

    2011-09-30

    The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.

  12. Calculating the X-Ray Fluorescence from the Planet Mercury Due to High-Energy Electrons

    NASA Technical Reports Server (NTRS)

    Burbine, T. H.; Trombka, J. I.; Bergstrom, P. M., Jr.; Christon, S. P.

    2005-01-01

    The least-studied terrestrial planet is Mercury due to its proximity to the Sun, which makes telescopic observations and spacecraft encounters difficult. Our lack of knowledge about Mercury should change in the near future due to the recent launching of MESSENGER, a Mercury orbiter. Another mission (BepiColombo) is currently being planned. The x-ray spectrometer on MESSENGER (and planned for BepiColombo) can characterize the elemental composition of a planetary surface by measuring emitted fluorescent x-rays. If electrons are ejected from an atom s inner shell by interaction with energetic particles such as photons, electrons, or ions, electrons from an outer shell can transfer to the inner shell. Characteristic x-rays are then emitted with energies that are the difference between the binding energy of the ion in its excited state and that of the ion in its ground state. Because each element has a unique set of energy levels, each element emits x-rays at a unique set of energies. Electrons and ions usually do not have the needed flux at high energies to cause significant x-ray fluorescence on most planetary bodies. This is not the case for Mercury where high-energy particles were detected during the Mariner 10 flybys. Mercury has an intrinsic magnetic field that deflects the solar wind, resulting in a bow shock in the solar wind and a magnetospheric cavity. Electrons and ions accelerated in the magnetosphere tend to follow its magnetic field lines and can impact the surface on Mercury s dark side Modeling has been done to determine if x-ray fluorescence resulting from the impact of high-energy electrons accelerated in Mercury's magnetosphere can be detected by MESSENGER. Our goal is to understand how much bulk chemical information can be obtained from x-ray fluorescence measurements on the dark side of Mercury.

  13. Compact, Passively Q-Switched Nd:YAG Laser for the MESSENGER Mission to the Planet Mercury

    NASA Technical Reports Server (NTRS)

    Krebs, Danny J.; Novo-Gradac, Anne-Marie; Li, Steven X.; Lindauer, Steven J.; Afzal, Robert S.; Yu, Antony

    2004-01-01

    A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter (MLA) instrument which is an instrument on the MESSENGER mission to the planet Mercury. The laser achieves 5.4 percent efficiency with a near diffraction limited beam. It has passed all space flight environmental tests at system, instrument, and satellite integration. The laser design draws on a heritage of previous laser altimetry missions, specifically ISESAT and Mars Global Surveyor; but incorporates thermal management features unique to the requirements of an orbit of the planet Mercury.

  14. Mercury's place among the terrestrial planets: Summary on what can be measured from ground

    NASA Astrophysics Data System (ADS)

    Warell, J.

    Close-range measurements during the multiple flybys of Mariner 10 past Mercury in 1974-1975 provided us with the bulk of information currently available on its physical properties. Understanding of its geology and evolution took a quantum leap, yet numerous questions were left unanswered and new questions were opened up regarding processes that shaped its appearance as observed today. Two main shortages in the Mariner 10 data set with respect to this understanding pertains to Mercury's crust: imaging coverage was less than half of its surface, and spectrometers for compositional determinations were unavailable. Since then, and particularly during the past decade or two, ground-based studies have provided a wealth of new information that aid in understanding the chemical and microphysical properties of its regolith. These include spectroscopy, imaging, photometry and polarimetry at visual, near infrared, thermal infrared and radar wavelengths. Modeling of these data sets, laboratory studies, and comparative planetological interpretations of its remotely-sensed properties to those of the Moon and other atmosphereless bodies in the inner solar system, has clarified many issues and revealed unexpected facets of this extreme end-member planet. These include the discovery of volatiles at the planet's poles, new atomic species in the exosphere, the realisation of the apparent similaries of the Mariner 10 and poorly known hemispheres, confirmation that the surface mineralogy is likely heterogeneous and dominated by intermediate feldspars with minor low-iron pyroxenes, very iron-poor and very strongly matured. Due to Mercury's location close to the Sun, the large mass of exogenically contributed chondritic and volatile-rich material since the solidification of its crust, may be of greater importance for the interpretation of the surface and bulk properties than those of any other body, and accentuates that this planet in many ways is drastically different from the

  15. The Role of Carbon in Core Formation Under Highly Reducing Conditions With Implications for the Planet Mercury

    NASA Technical Reports Server (NTRS)

    Vander Kaaden, Kathleen E..; McCubbin, Francis M.; Ross, D. Kent; Draper, David S.

    2017-01-01

    Results from the MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) spacecraft have shown elevated abundances of carbon on the surface of Mercury. Furthermore, the X-Ray Spectrometer on board MESSENGER measured elevated abundances of sulfur and low abundances of iron, suggesting the planet's oxygen fugacity (fO2) is several log10 units below the Iron-Wüstite (IW) buffer. Similar to the role of other volatiles (e.g. sulfur) on highly reducing planetary bodies, carbon is expected to behave differently than it would under higher fO2. As discussed by Nittler et al. and Hauck et al., under such highly reducing conditions, the majority of the iron partitions into the core. On Mercury, this resulted in a relatively large core and a thin mantle. Using a composition similar to the largest volcanic field on the planet (the northern volcanic plains), Vander Kaaden and McCubbin conducted sink-float experiments to determine the density of melts and minerals on Mercury. They showed that graphite would be the only buoyant mineral in a mercurian magma ocean. Therefore, Vander Kaaden and McCubbin proposed a possible primary flotation crust on the planet composed of graphite. Concurrently, Peplowski et al. used GRS data from MESSENGER to show an average northern hemisphere abundance of C on the planet of 1.4 +/- 0.9 wt%. However, as this result was only at the one-sigma detection limit, possible carbon abundances at the three-sigma detection limit for Mercury range from 0 to 4.1 wt% carbon. Additionally, Murchie et al. investigated the possible darkening agent on Mercury and concluded that coarse-grained graphite could darken high reflectance plains to the low reflectance material. To further test the possibility of elevated abundances of carbon in Mercury's crust, Peplowski et al. used the low-altitude MESSENGER data to show that carbon is the only material consistent with both the visible to near-infrared spectra and the neutron measurements of low

  16. Mercury Sodium Atmosphere Spectral Imager (MSASI) - taking High Resolution Interferometry to the Planets

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Ichiro; Kameda, Shingo; Korablev, Oleg; Rees, David

    The Mercury Sodium Atmosphere Spectral Imager (MSASI) on the Mercury Magnetospheric Orbiter of the JAXA / ESA Bepi-Colombo (BC) Mission will address a range of fundamental scientific questions pertaining to Mercury's exosphere. The measurements will provide new information on regolith-exosphere-magnetosphere coupling as well as new understanding of the dynamics governing the exosphere bounded by the planetary surface, the solar wind and interplanetary space. MSASI is a high-dispersion visible spectrometer working in the spectral region near the sodium D2 emission (589 nm), a major constituent of the Mercury exosphere. A single high-resolution Fabry-Perot etalon is used in combination with a narrow-band interference filter to achieve a compact and efficient instrument design. The etalon and filter are extremely stable with respect to long-term ageing and temperature variations. Full-disk images of the planet are obtained by means of a single-axis scanning mirror in combination with the spin of the MMO spacecraft . This paper presents an overview of the MSASI and the design of the Fabry- Perot interferometer used as its spectral analyser. It is concluded that: (1) The MSASI optical design is practical and can be implemented without new or critical technology developments; (2) The thermally-stable etalon design is based on concepts, designs and materials that have a good space heritage. (3) The MSASI instrument will achieve a high SNR (˜10) in the range of 2K-10M Rayleigh.

  17. Contributions of ISA accelerometer to BepiColombo exploration of planet Mercury: status

    NASA Astrophysics Data System (ADS)

    Iafolla, Valerio; Fiorenza, Emiliano; Lefevre, Carlo; Massimo Lucchesi, David; Lucente, Marco; Magnafico, Carmelo; Nozzoli, Sergio; Peron, Roberto; Santoli, Francesco

    2014-05-01

    To be launched in 2016, ESA mission BepiColombo will perform a thorough study of the planet Mercury and its environment. Among the wide range of its scientific objectives, an important set is constituted by the so-called Radio Science Experiments (RSE), which will study the gravitational field and rotation of the planet, and will perform very precise tests of general relativity theory. In order to reach the required level of accuracy in recovering the relevant parameters, the data coming from the high-sensitivity ISA (Italian Spring Accelerometer) instrument onboard the Mercury Planetary Orbiter (MPO) will be used - the first time for a deep-space probe - in the orbit determination and parameter estimation procedure. Following a brief description of the RSE in the context of the mission, the instrument and its wide capabilities will be reviewed. In particular the overall measurement procedure will be discussed, along with recent and current work on instrument calibration (both on-ground and in-orbit), operations planning, data handling and processing and archiving.

  18. Contributions of ISA accelerometer to BepiColombo exploration of planet Mercury: current status

    NASA Astrophysics Data System (ADS)

    Iafolla, V.; Fiorenza, E.; Lefevre, C.; Lucchesi, D. M.; Lucente, M.; Magnafico, C.; Nozzoli, S.; Peron, R.; Santoli, F.

    2013-09-01

    The BepiColombo ESA mission will perform a thorough study of the planet Mercury and its environment. Among the wide range of its scientific objectives, an important set is constituted by the so-called Radio Science Experiments (RSE), which will study the gravitational field and rotation of the planet, and will perform very precise tests of general relativity theory. In order to reach the required level of accuracy in recovering the relevant parameters, the data coming from the high-sensitivity ISA (Italian Spring Accelerometer) instrument onboard the Mercury Planetary Orbiter (MPO) will be used — the first time for a deep-space probe — in the orbit determination and parameter estimation procedure. Following a brief description of the RSE in the context of the mission, the instrument and its wide capabilities will be reviewed. In particular the overall measurement procedure will be discussed, along with recent and current work on instrument calibration —both on-groun d and in-orbit—operations planning, data handling and processing and archiving.

  19. Contributions of ISA accelerometer to BepiColombo exploration of planet Mercury

    NASA Astrophysics Data System (ADS)

    Iafolla, Valerio; Fiorenza, Emiliano; Lefevre, Carlo; Lucchesi, David; Magnafico, Carmelo; Nozzoli, Sergio; Peron, Roberto; Reale, Andrea; Ricotta, Angelo; Santoli, Francesco

    To be launched in 2014, ESA mission BepiColombo will perform a thorough study of the planet Mercury and its environment. Among the wide range of its scientific objectives, an important set is constituted by the so-called Radio Science Experiments (RSE), which will study the gravitational field and rotation of the planet, and will perform very precise tests of general relativity theory. In order to reach the required level of accuracy in recovering the relevant parameters, the data coming from the high-sensitivity ISA (Italian Spring Accelerometer) instrument onboard the Mercury Planetary Orbiter (MPO) will be used — the first time for a deep-space probe — in the orbit determination and parameter estimation procedure. Following a brief description of the mission and RSE, the instrument and its wide capabilities will be reviewed. In particular the updated error budget for the acceleration measurements will be shown, together with a discussion of the calibration procedures, both on-ground and in-orbit, which are currently under definition.

  20. Assessing the Behavior of Typically Lithophile Elements Under Highly Reducing Conditions Relevant to the Planet Mercury

    NASA Technical Reports Server (NTRS)

    Rowland, Rick, II; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Danielson, Lisa R.

    2017-01-01

    With the data returned from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition (e.g., Evans et al. 2012; Nittler et al. 201 l; Peplowski et al. 2012; Weider et al. 2012). The high Sand low FeO contents observed from MESSENGER on the planet's surface suggests a low oxygen fugacity of the present planetary materials. Estimates of the oxygen fugacity for Mercurian magmas are approximately 3- 7 log units below the Iron-Wiistite (Fe-FeO) oxygen buffer (McCubbin et al. 2012; Zolotov et al. 2013), several orders of magnitude more reducing than other terrestrial bodies we have data from such as the Earth, Moon, or Mars (Herd 2008; Sharp, McCubbin, and Shearer 2013; Wadhwa 2008). Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions are available in our collections (e.g., enstatite chondrites, achondrites, aubrites). The goal of this study is to conduct experiments at high pressure and temperature conditions to determine the elemental partitioning behavior of typically lithophile elements as a function of decreasing oxygen fugacity.

  1. "Dry" Mercury and "wet" Mars: comparison of two terrestrial planets with strongly differing orbital frequencies

    NASA Astrophysics Data System (ADS)

    Kochemasov, G.

    The modern wave planetology states that "orbits make structures". It means that all celestial bodies moving in non-round keplerian elliptical (and parabolic) orbits and rotating (all bodies rotate) are subjected to warping action of inertia-gravity waves . The waves appear in bodies due to periodically changing accelerations during cyclic orbital movements; they have a stationary character, 4 intersecting ortho- and diagonal directions and various lengths. Wave intersections and superpositions produce uplifting (+), subsiding (-) and neutral (0) regularly disposed tectonic blocks. Their sizes depend on wavelengths. The longest in a globe fundamental wave1 long 2πR is responsible for ubiquitous appearance in all celestial bodies of tectonic dichotomy or segmentation (2πR-structure). The first overtone wave2 produces tectonic sectoring (πR-structure). On this already complex wave structurization are superposed individual waves whose lengths are proportional to orbital periods or inversely proportional to orbital frequencies: higher frequency - smaller waves, lower frequency - larger waves. These waves are responsible for production of tectonic granules. In a row of terrestrial planets according to their orb. fr. sizes of the granules are as follows (this row can be started with the solar photosphere that orbits around the center of the solar system with about one month period): Photosphere πR/60, Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1. By this way a bridging is made between planets and stars in that concerns their wave structurization. The calculated granule sizes are rather known in nature. The solar supergranulation about 30-40 thousand km across, prevailing sizes of mercurian craters ˜500 km in diameter (a radar image from Earth), venusian "blobs" ˜3000 km across, superstructures of the Earth's cratons ˜ 5000 km across (seen now on NASA image PIA04159), martian elongated shape due to 2 waves inscribed in equator, asteroids

  2. Assessing the Behavior of Typically Lithophile Elements Under Highly Reducing Conditions Relevant to the Planet Mercury

    NASA Technical Reports Server (NTRS)

    Rowland, Rick, II; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Danielson, Lisa R.

    2017-01-01

    With the data returned from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition. The high Sand low FeO contents observed from MESSENGER suggest a low oxygen fugacity of the present materials on the planet's surface. Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples, estimated at approximately 3-7 log units below the Iron-Wtistite (lW) oxygen buffer, several orders of magnitude more reducing than other terrestrial bodies we have data from. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions (e.g., enstatite chondrites, achondrites, aubrites) are available in our collections for examination of this change in geochemical affinity. Our goal is to determine the elemental partitioning behavior of typically lithophile elements at lower oxygen fugacity as a function of temperature and pressure. Experiments were conducted at I GPa in a 13 mm QUICKpress piston cylinder and at 4 GPa in an 880-ton multianvil press, at temperatures up to 1850degC. The composition of starting materials for the experiments were designed so the final run products contained metal, silicate melt, and sulfide melt phases. Oxygen fugacity was controlled in the experiments by adding silicon metal to the samples, in order to utilize the Si-Si02 buffer, which is approximately 5 log units more reducing than the IW buffer at our temperatures of interest. The target silicate melt composition was diopside (CaMgSi206) because measured surface compositions indicate partial melting of a pyroxene-rich mantle. The results of our experiments will aid in our understanding of

  3. Mercury

    NASA Technical Reports Server (NTRS)

    Gault, D. E.; Burns, J. A.; Cassen, P.; Strom, R. G.

    1977-01-01

    Prior to the flight of the Mariner 10 spacecraft, Mercury was the least investigated and most poorly known terrestrial planet (Kuiper 1970, Devine 1972). Observational difficulties caused by its proximity to the Sun as viewed from Earth caused the planet to remain a small, vague disk exhibiting little surface contrast or details, an object for which only three major facts were known: 1. its bulk density is similar to that of Venus and Earth, much greater than that of Mars and the Moon; 2. its surface reflects electromagnetic radiation at all wavelengths in the same manner as the Moon (taking into account differences in their solar distances); and 3. its rotation period is in 2/3 resonance with its orbital period. Images obtained during the flyby by Mariner 10 on 29 March 1974 (and the two subsequent flybys on 21 September 1974 and 16 March 1975) revealed Mercury's surface in detail equivalent to that available for the Moon during the early 1960's from Earth-based telescopic views. Additionally, however, information was obtained on the planet's mass and size, atmospheric composition and density, charged-particle environment, and infrared thermal radiation from the surface, and most significantly of all, the existence of a planetary magnetic field that is probably intrinsic to Mercury was established. In the following, this new information is summarized together with results from theoretical studies and ground-based observations. In the quantum jumps of knowledge that have been characteristic of "space-age" exploration, the previously obscure body of Mercury has suddenly come into sharp focus. It is very likely a differentiated body, probably contains a large Earth-like iron-rich core, and displays a surface remarkably similar to that of the Moon, which suggests a similar evolutionary history.

  4. Resolved Image of Surface of the Planet Mercury in Longitude Sector 210^O to 290^OW

    NASA Astrophysics Data System (ADS)

    Ksanfomality, L. V.

    2006-08-01

    Results of observations of the unknown portion of Mercury are presented. The observations were made by the millisecond exposure method. The planet's disk subtended, on average, 7 arcsec. Geocentric distance of Mercury was 0.87 AU. The observations were carried out in a near IR-range. For the instrument with diameter D=1.25 m, on wavelength λ = 600 nanometer the ratio 1.22 λ/D = 0.15 arc sec, limiting resolution on surface of the planet should make exactly 100 km. Under good atmospheric conditions a sufficient number of initial electronic images were obtained that when stacked increased the signal to noise ratio and gave rise to resolution that dramatically shows unprecedented detail of the surface albedo and physical features. By processing a great number of electronic images, a sufficiently distinct synthesized image of the planet's surface was obtained. The most prominent formation in the sector 210° to 290°W longitude, a region not imaged by Mariner 10 is a giant basin centered at about 8N, 280W. The inner portion of this double rimmed basin extends 1000 km across. The total dimension of the outer eroded rim is slightly more than 2000 km. This basin includes and extends west and north of the dark albedo feature known as Solitudo Criophori. Many well defined impact craters have also been imaged. Some regions within the basin area have circular rims that apparently lack rayed structure or evidence of ejecta material. An attempt has been made to restore information about relief of the 210° to 290°W (70° to 150°E) longitude sector. In addition, regions on the order of 10° of latitude and 10° of longitude have been examined and reveal rayed craters in comparable detail to the Aericebo radar imaging and, at the same location of craters where radar backscatter indicates infilling by volatiles or some other highly coherent backscattering material. Implications of the huge basin for the geophysics of Mercury are discussed.

  5. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Areal measurement of Mercury's first quadrant. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Various linear and areal measurements of Mercury's first quadrant which were used in geological map preparation, map analysis, and statistical surveys of crater densities are discussed. Accuracy of each method rests on the determination of the scale of the photograph, i.e., the conversion factor between distances on the planet (in km) and distances on the photograph (in cm). Measurement errors arise due to uncertainty in Mercury's radius, poor resolution, poor coverage, high Sun angle illumination in the limb regions, planetary curvature, limited precision in measuring instruments, and inaccuracies in the printed map scales. Estimates are given for these errors.

  6. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Areal measurement of Mercury's first quadrant. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Various linear and areal measurements of Mercury's first quadrant which were used in geological map preparation, map analysis, and statistical surveys of crater densities are discussed. Accuracy of each method rests on the determination of the scale of the photograph, i.e., the conversion factor between distances on the planet (in km) and distances on the photograph (in cm). Measurement errors arise due to uncertainty in Mercury's radius, poor resolution, poor coverage, high Sun angle illumination in the limb regions, planetary curvature, limited precision in measuring instruments, and inaccuracies in the printed map scales. Estimates are given for these errors.

  7. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Thermal histories of Mercury and the Moon. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    To determine a planet's thermal history, a wide range of data is necessary. These data include remote sensing results, photogeologic evidence, magnetic field and remanent magnetization data, composition and ages of samples, and physical parameters of the planet and its orbit. Few of these data form unambiguous constraints for thermal models of Mercury. Igneous Chronology as the time history of the differentiation and igneous activity, is defined. Igneous Chronology is used here in the sense of the apparent igneous or relative chronology of geologic events, such as plains formation (through whatever mechanism) relative to the crater production and tectonic history (lineament and scarp formation).

  8. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Thermal histories of Mercury and the Moon. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    To determine a planet's thermal history, a wide range of data is necessary. These data include remote sensing results, photogeologic evidence, magnetic field and remanent magnetization data, composition and ages of samples, and physical parameters of the planet and its orbit. Few of these data form unambiguous constraints for thermal models of Mercury. Igneous Chronology as the time history of the differentiation and igneous activity, is defined. Igneous Chronology is used here in the sense of the apparent igneous or relative chronology of geologic events, such as plains formation (through whatever mechanism) relative to the crater production and tectonic history (lineament and scarp formation).

  9. Mercury-T: A new code to study tidally evolving multi-planet systems. Applications to Kepler-62

    NASA Astrophysics Data System (ADS)

    Bolmont, Emeline; Raymond, Sean N.; Leconte, Jeremy; Hersant, Franck; Correia, Alexandre C. M.

    2015-11-01

    A large proportion of observed planetary systems contain several planets in a compact orbital configuration, and often harbor at least one close-in object. These systems are then most likely tidally evolving. We investigate how the effects of planet-planet interactions influence the tidal evolution of planets. We introduce for that purpose a new open-source addition to the MercuryN-body code, Mercury-T, which takes into account tides, general relativity and the effect of rotation-induced flattening in order to simulate the dynamical and tidal evolution of multi-planet systems. It uses a standard equilibrium tidal model, the constant time lag model. Besides, the evolution of the radius of several host bodies has been implemented (brown dwarfs, M-dwarfs of mass 0.1 M⊙, Sun-like stars, Jupiter). We validate the new code by comparing its output for one-planet systems to the secular equations results. We find that this code does respect the conservation of total angular momentum. We applied this new tool to the planetary system Kepler-62. We find that tides influence the stability of the system in some cases. We also show that while the four inner planets of the systems are likely to have slow rotation rates and small obliquities, the fifth planet could have a fast rotation rate and a high obliquity. This means that the two habitable zone planets of this system, Kepler-62e ad f are likely to have very different climate features, and this of course would influence their potential at hosting surface liquid water. The code is 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/583/A116

  10. Assessing the Behavior of Typically Lithophile Elements Under Highly Reducing Conditions Relevant to the Planet Mercury

    NASA Technical Reports Server (NTRS)

    Rowland, Rick, II; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Danielson, Lisa R.

    2017-01-01

    With the data returned from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (lvtESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition. The high S and low FeO contents observed from MESSENGER suggest a low oxygen fugacity of the present materials on the planet's surface. Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples, estimated at approximately 3-7 log units below the Iron-Wustite (lW) oxygen buffer, several orders of magnitude more reducing than other terrestrial bodies we have data from. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions (e.g., enstatite chondrites, achondrites, aubrites) are available in our collections for examination of this change in geochemical affinity. Our goal is to determine the elemental partitioning behavior of typically lithophile elements at lower oxygen fugacity as a function of temperature and pressure. Experiments were conducted at I GPa in a 13 mm QUICKpress piston cylinder and at 4 GPa in an 880-ton multi-anvil press, at temperatures up to 1850 C. The composition of starting materials for the experiments were designed so the final run products contained metal, silicate melt, and sulfide melt phases. Oxygen fugacity was controlled in the experiments by adding silicon metal to the samples, in order to utilize the Si-Si02 buffer, which is approx. 5 log units more reducing than the IW buffer at our temperatures of interest. The target silicate melt composition was diopside (CaMgSi206) because measured surface compositions indicate partial melting of a pyroxene-rich mantle. The results of our experiments will aid in our understanding of the

  11. PHOTOPHORETIC SEPARATION OF METALS AND SILICATES: THE FORMATION OF MERCURY-LIKE PLANETS AND METAL DEPLETION IN CHONDRITES

    SciTech Connect

    Wurm, Gerhard; Trieloff, Mario; Rauer, Heike

    2013-05-20

    Mercury's high uncompressed mass density suggests that the planet is largely composed of iron, either bound within metal (mainly Fe-Ni) or iron sulfide. Recent results from the MESSENGER mission to Mercury imply a low temperature history of the planet which questions the standard formation models of impact mantle stripping or evaporation to explain the high metal content. Like Mercury, the two smallest extrasolar rocky planets with mass and size determination, CoRoT-7b and Kepler-10b, were found to be of high density. As they orbit close to their host stars, this indicates that iron-rich inner planets might not be a nuisance of the solar system but be part of a general scheme of planet formation. From undifferentiated chondrites, it is also known that the metal to silicate ratio is highly variable, which must be ascribed to preplanetary fractionation processes. Due to this fractionation, most chondritic parent bodies-most of them originated in the asteroid belt-are depleted in iron relative to average solar system abundances. The astrophysical processes leading to metal silicate fractionation in the solar nebula are essentially unknown. Here, we consider photophoretic forces. As these forces particularly act on irradiated solids, they might play a significant role in the composition of planetesimals forming at the inner edge of protoplanetary disks. Photophoresis can separate high thermal conductivity materials (iron) from lower thermal conductivity solids (silicate). We suggest that the silicates are preferentially pushed into the optically thick disk. Subsequent planetesimal formation at the edge moving outward leads to metal-rich planetesimals close to the star and metal depleted planetesimals farther out in the nebula.

  12. Future Mercury Exploration: Unique Science Opportunities from Our Solar System's Innermost Planet

    NASA Astrophysics Data System (ADS)

    Chabot, N. L.; McNutt, R. L.; Blewett, D. T.; Denevi, B. W.; Ernst, C. M.; Mazarico, E.; Jozwiak, L. M.

    2017-02-01

    Mercury is one of only five inner solar system terrestrial bodies, each of which is unique. What properties and processes made these bodies so diverse? Future planetary exploration must include Mercury to make advances on this fundamental question.

  13. James Craig Watson, First Director of Washburn Observatory: His Obsession with the Intra-Mercurial Planet Vulcan

    NASA Astrophysics Data System (ADS)

    Sheehan, William

    1996-05-01

    The first director of the Washburn Observatory, Watson began his career at the University of Michigan, where he discovered more than a score of asteroids and planned (but did not live to carry out) the first search for a trans-Neptunian planet. He became a strong supporter of Le Verrier's hypothesis that a planet closer to the Sun than Mercury (Vulcan) was causing the anomalous advance of 38" of arc per century of Mercury's perihelion, and mounted a special search for Vulcan at the July 29, 1878 total eclipse, at Separation, Wyoming, recording two strange reddish stars near the Sun which he assumed were intra-Mercurial bodies. With the exception of Lewis Swift at Denver, Colorado, no one else confirmed his observations, and they were sharply criticized by Clinton College (New York) astronomer C. H. F. Peters. Nevertheless, Watson remained absolutely convinced of what he had seen, and his move from Ann Arbor to Madison in 1879 was partly motivated by the prospects of obtaining better instruments with which to further his search for Vulcan, which became the obsession of his later years. He was in the process of constructing an underground solar observatory from which he hoped to see stars near the Sun in broad daylight when he died, unexpectedly, in 1880. Though it is now known that Vulcan does not exist, Watson's observations at the July 1878 eclipse remain problematic; it is probable that he observed at least one and possibly two pygmy comets in the neighborhood of the Sun.

  14. Mercury

    MedlinePlus

    Mercury is an element that is found in air, water and soil. It has several forms. Metallic mercury is a shiny, silver-white, odorless liquid. If ... with other elements to form powders or crystals. Mercury is in many products. Metallic mercury is used ...

  15. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution: Introduction. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The relative ages of various geologic units and structures place tight constraints on the origin of the Moon and the planet Mercury, and thus provide a better understanding of the geologic histories of these bodies. Crater statistics, a reexamination of lunar geologic maps, and the compilation of a geologic map of a quarter of Mercury's surface based on plains units dated relative to crater degradation classes were used to determine relative ages. This provided the basis for deducing the origin of intercrater plains and their role in terrestrial planet evolution.

  16. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution: Introduction. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The relative ages of various geologic units and structures place tight constraints on the origin of the Moon and the planet Mercury, and thus provide a better understanding of the geologic histories of these bodies. Crater statistics, a reexamination of lunar geologic maps, and the compilation of a geologic map of a quarter of Mercury's surface based on plains units dated relative to crater degradation classes were used to determine relative ages. This provided the basis for deducing the origin of intercrater plains and their role in terrestrial planet evolution.

  17. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Discussion of the nature, origin and role of the intercrater plains of Mercury and the Moon. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The nature and origin of the intercrater plains of Mercury and the Moon as determined through geologic mapping, crater statistics, and remotely sensed data are summarized. Implications of these results regarding scarp formation, absolute ages, and terrestrial planet surfaces are included. The role of the intercrater plains is defined and future work which might lead to a better understanding of these units and terrestrial planet evolution is outlined.

  18. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Discussion of the nature, origin and role of the intercrater plains of Mercury and the Moon. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The nature and origin of the intercrater plains of Mercury and the Moon as determined through geologic mapping, crater statistics, and remotely sensed data are summarized. Implications of these results regarding scarp formation, absolute ages, and terrestrial planet surfaces are included. The role of the intercrater plains is defined and future work which might lead to a better understanding of these units and terrestrial planet evolution is outlined.

  19. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Chronology of surface history of Mercury. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Phases in the history of the planet Mercury include: (1) condensation and accretion; (2) heating; (3) planetary expansion during heavy bombardment; (4) tidal spin-down and lineament formation; (5) P5 plains emplacement; (6) P4 plains emplacement; (7) peak planetary volume in P3 period; (8) scarp formation; (9) Caloris Basin formation, late class 3; (10) scarp formation and P2 plains formation; (11) smooth plains formation in and around large basins; (12) late or local tectonic stress; and (13) quiescent class 1 period. Although the cooling and contraction of the lithosphere are complete, the core remains molten as an active dynamo, producing the magnetic fields detected by Mariner 10. Plains produced since core formation (P3 to P-1) should record its magnetic activity. Cratering during the Class 2 and Class 1 periods is probably not enough to distribute ballistic materials and homogenize any color differences.

  20. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Chronology of surface history of Mercury. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Phases in the history of the planet Mercury include: (1) condensation and accretion; (2) heating; (3) planetary expansion during heavy bombardment; (4) tidal spin-down and lineament formation; (5) P5 plains emplacement; (6) P4 plains emplacement; (7) peak planetary volume in P3 period; (8) scarp formation; (9) Caloris Basin formation, late class 3; (10) scarp formation and P2 plains formation; (11) smooth plains formation in and around large basins; (12) late or local tectonic stress; and (13) quiescent class 1 period. Although the cooling and contraction of the lithosphere are complete, the core remains molten as an active dynamo, producing the magnetic fields detected by Mariner 10. Plains produced since core formation (P3 to P-1) should record its magnetic activity. Cratering during the Class 2 and Class 1 periods is probably not enough to distribute ballistic materials and homogenize any color differences.

  1. The extreme ultraviolet albedos of the planet Mercury and of the moon

    NASA Technical Reports Server (NTRS)

    Wu, H. H.; Broadfoot, A. L.

    1977-01-01

    The albedo of the moon in the far UV was measured by Mariner 10 at a solar phase angle of 74 deg, and the geometric albedo of Mercury was measured in same wavelength range (584-1657 A) at solar phase angles ranging from 50 to 120 deg. For both the moon and Mercury there is a general increase in albedo for wavelengths decreasing from 1657 to 584 A. The ratio of the albedos of Mercury and the moon increases from about 0.6 to 0.8 in the range 600-1600 A. This merely points to a difference in the surfaces of the moon and Mercury, there being insufficient data to make any conclusions regarding the nature of the difference.

  2. The extreme ultraviolet albedos of the planet Mercury and of the moon

    NASA Technical Reports Server (NTRS)

    Wu, H. H.; Broadfoot, A. L.

    1977-01-01

    The albedo of the moon in the far UV was measured by Mariner 10 at a solar phase angle of 74 deg, and the geometric albedo of Mercury was measured in same wavelength range (584-1657 A) at solar phase angles ranging from 50 to 120 deg. For both the moon and Mercury there is a general increase in albedo for wavelengths decreasing from 1657 to 584 A. The ratio of the albedos of Mercury and the moon increases from about 0.6 to 0.8 in the range 600-1600 A. This merely points to a difference in the surfaces of the moon and Mercury, there being insufficient data to make any conclusions regarding the nature of the difference.

  3. ADDITIONAL OBSERVATIONS OF PLANETS AND QUASI-STELLAR RADIO SOURCES AT 3 MM,

    DTIC Science & Technology

    MERCURY ( PLANET ), VENUS( PLANET ), PERIODIC VARIATIONS, RADIO ASTRONOMY, SPECTRUM SIGNATURES...EXTRATERRESTRIAL RADIO WAVES, SOURCES), GALAXIES, BLACKBODY RADIATION, BRIGHTNESS, TEMPERATURE, MARS( PLANET ), JUPITER( PLANET ), SATURN( PLANET

  4. Mercury

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002476.htm Mercury To use the sharing features on this page, please enable JavaScript. This article discusses poisoning from mercury. This article is for information only. Do NOT ...

  5. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Alternative thermal histories. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Interpretations supporting a differentiated, once active Mercury are listed. Alternative scenarios of the planet's thermal history involve: different distributions of accreted materials, including uranium and thorium-rich materials; variations of early melting; and different modes of plains and scarp formation. Arguments are advanced which strongly favor plains formation by volcanism, lack of a primordial surface, and possible identification of remnant tensional features. Studies of remotely sensed data which strongly suggest a modestly homogeneous surface of silicates imply core separation. Reasons for accepting or rejecting various hypotheses for thermal histories of the planet are mentioned.

  6. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Alternative thermal histories. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Interpretations supporting a differentiated, once active Mercury are listed. Alternative scenarios of the planet's thermal history involve: different distributions of accreted materials, including uranium and thorium-rich materials; variations of early melting; and different modes of plains and scarp formation. Arguments are advanced which strongly favor plains formation by volcanism, lack of a primordial surface, and possible identification of remnant tensional features. Studies of remotely sensed data which strongly suggest a modestly homogeneous surface of silicates imply core separation. Reasons for accepting or rejecting various hypotheses for thermal histories of the planet are mentioned.

  7. Radar studies of the planets. [radar measurements of lunar surface, Mars, Mercury, and Venus

    NASA Technical Reports Server (NTRS)

    Ingalls, R. P.; Pettengill, G. H.; Rogers, A. E. E.; Sebring, P. B. (Editor); Shapiro, I. I.

    1974-01-01

    The radar measurements phase of the lunar studies involving reflectivity and topographic mapping of the visible lunar surface was ended in December 1972, but studies of the data and production of maps have continued. This work was supported by Manned Spacecraft Center, Houston. Topographic mapping of the equatorial regions of Mars has been carried out during the period of each opposition since that of 1967. The method comprised extended precise traveling time measurements to a small area centered on the subradar point. As measurements continued, planetary motions caused this point to sweep out extensive areas in both latitude and longitude permitting the development of a fairly extensive topographical map in the equatorial region. Radar observations of Mercury and Venus have also been made over the past few years. Refinements of planetary motions, reflectivity maps and determinations of rotation rates have resulted.

  8. OBSERVATIONS OF PLANETS AND QUASI-STELLAR RADIO SOURCES AT 3 MM.

    DTIC Science & Technology

    EXTRATERRESTRIAL RADIO WAVES), (* PLANETS , STARS, VENUS( PLANET ), MARS( PLANET ), MERCURY ( PLANET ), PLANETARY ATMOSPHERES, GALAXIES, ASTROPHYSICS, TEMPERATURE, MEASUREMENT, MICROWAVE FREQUENCY, ASTRONOMY, RADIO ASTRONOMY.

  9. Dance of the Planets

    ERIC Educational Resources Information Center

    Riddle, Bob

    2005-01-01

    As students continue their monthly plotting of the planets along the ecliptic they should start to notice differences between inner and outer planet orbital motions, and their relative position or separation from the Sun. Both inner and outer planets have direct eastward motion, as well as retrograde motion. Inner planets Mercury and Venus,…

  10. Dance of the Planets

    ERIC Educational Resources Information Center

    Riddle, Bob

    2005-01-01

    As students continue their monthly plotting of the planets along the ecliptic they should start to notice differences between inner and outer planet orbital motions, and their relative position or separation from the Sun. Both inner and outer planets have direct eastward motion, as well as retrograde motion. Inner planets Mercury and Venus,…

  11. Extrasolar planets

    PubMed Central

    Lissauer, Jack J.; Marcy, Geoffrey W.; Ida, Shigeru

    2000-01-01

    The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However, these models require some modifications to explain the properties of the observed extrasolar planetary systems. PMID:11035782

  12. Extrasolar planets.

    PubMed

    Lissauer, J J; Marcy, G W; Ida, S

    2000-11-07

    The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However, these models require some modifications to explain the properties of the observed extrasolar planetary systems.

  13. From Mercury to Vesta: present studies confirm conclusions of the wave planetology about regularly changing rocky planets characteristics with increasing solar distance

    NASA Astrophysics Data System (ADS)

    Kochemasov, G. G.

    2012-09-01

    I. Kepler has shown that all heavenly bodies move in elliptical orbits. After about 100 years I. Newton has shown that the bodies are not simple points but have certain masses influencing orbits. After about 300 years now one may say that the bodies are not simple structureless masses but have vertical and horizontal structural and compositional characteristics tied to their orbits. The comparative wave planetology (Kochemasov, 1992-2012) deals with these characteristics in relat ion to orbital characteristics of planetary bodies. Warping bodies waves appear in them due to keplerian orbits with changing bodies ' accelerations . Mercury's data were predicted before the MESSENGER era due to an extrapolation of known regularities. Ves ta's convexoconcave shape is a feature (consequence) of the warping fundamental wave present in all bodies, for example, in Ceres, Hyperion, Earth, and Mars. A protrusion of mountain on the concave subsiding side (hemisphere) is also typical: the Hawaii in the Pacific, the Pl. Boreale, Elysium Mons on the northern lowlands of Mars. Planetary at mos pheres as a product of "sweeping out" volatiles from solid bodies increase their masses with diminishing solar distance (increasing orbital frequencies) and diminishing relief range, and tectonic granulation. Recent MESSENGER's data on Mercury [1, 10-12] characterize it as a planet with relat ively low surface relief range, low albedo contrast, Mg-rich basaltic (komatiitic, enstatitic) surface, a relat ively fine tectonic granulation (magnetic field t ight undulations, Fig. 4[11]). These features were predicted long ago based on some indirect evidences and mainly on regularities of the wave planetology [2- 9 & others]. This branch of planetology connects physical-chemical characteristics of celestial bodies with their orbital frequencies. Terrestrial planets from Mercury to asteroids (the mini-planet Vesta) according to their orbital frequencies increase sizes of tectonic granules (Mercury

  14. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Geologic mapping of Mercury and the Moon. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The geologic framework of the intercrater plains on Mercury and the Moon as determined through geologic mapping is presented. The strategies used in such mapping are discussed first. Then, because the degree of crater degradation is applied to both mapping and crater statistics, the correlation of degradation classification of lunar and Mercurian craters is thoroughly addressed. Different imaging systems can potentially affect this classification, and are therefore also discussed. The techniques used in mapping Mercury are discussed in Section 2, followed by presentation of the Geologic Map of Mercury in Section 3. Material units, structures, and relevant albedo and color data are discussed therein. Preliminary conclusions regarding plains' origins are given there. The last section presents the mapping analyses of the lunar intercrater plains, including tentative conclusions of their origin.

  15. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Geologic mapping of Mercury and the Moon. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The geologic framework of the intercrater plains on Mercury and the Moon as determined through geologic mapping is presented. The strategies used in such mapping are discussed first. Then, because the degree of crater degradation is applied to both mapping and crater statistics, the correlation of degradation classification of lunar and Mercurian craters is thoroughly addressed. Different imaging systems can potentially affect this classification, and are therefore also discussed. The techniques used in mapping Mercury are discussed in Section 2, followed by presentation of the Geologic Map of Mercury in Section 3. Material units, structures, and relevant albedo and color data are discussed therein. Preliminary conclusions regarding plains' origins are given there. The last section presents the mapping analyses of the lunar intercrater plains, including tentative conclusions of their origin.

  16. Mercury: The Image of the Planet in the 210°-285° W Longitude Range Obtained by the Short-Exposure Method

    NASA Astrophysics Data System (ADS)

    Ksanfomality, L. V.

    2003-11-01

    For the purpose of obtaining images of the unknown portion of Mercury, we continued the previously started series of observations of this planet by the short exposure method. Several thousand electronic images of Mercury have been acquired on 1-2 May 2002 under good meteorological conditions at the high-altitude Skinakas Astrophysical Observatory of Iraklion University (Crete, Greece, 35°13' E, 24°54' N) during the evening elongation. The phase angle of Mercury was 95°-99° and the observed range of longitudes was 210°-285° W. Observations were carried out using Ritchy-Chrétien telescope (D = 1.29 m, F = 9.857 m) with the KS 19 filter cutting wavelengths shorter than about 700 nm. The planet's disk was seen, on average, at an angle of 7.75'' arcsec. The image scale was equal to 47.8 μm/arcsec. We used a CCD with a pixel size of 7.4 × 7.4 μm in the regime of short exposures. By processing a great number of electronic images, we succeeded in obtaining a sufficiently distinct synthesized image of the unknown portion of Mercury's surface. The most prominent formation in this region is a giant basin (or cratered ``mare'') centered at about 8° N, 280° W, which was given a working name ``Skinakas basin'' (after the name of the observatory where observations were made). By its size, the interior part of this basin exceeds the largest lunar Mare Imbrium. As opposed to Mare Imbrium, the Skinakas basin is presumably of impact origin. Its relief resembles that of Caloris Planitia but the size is much larger. A series of smaller formations are also seen on synthesized images. The resolution obtained on the surface of Mercury is about 100 km, which is close to the telescope diffraction limit. Also considered are the published theoretical estimations of the possible advantages offered by the short exposure method. Some results obtained by other research groups are discussed.

  17. Chlorine on the surface of Mercury: MESSENGER gamma-ray measurements and implications for the planet's formation and evolution

    NASA Astrophysics Data System (ADS)

    Evans, Larry G.; Peplowski, Patrick N.; McCubbin, Francis M.; McCoy, Timothy J.; Nittler, Larry R.; Zolotov, Mikhail Yu.; Ebel, Denton S.; Lawrence, David J.; Starr, Richard D.; Weider, Shoshana Z.; Solomon, Sean C.

    2015-09-01

    Orbital measurements obtained by the MESSENGER Gamma-Ray Spectrometer have been analyzed to determine the surface abundance of chlorine in Mercury's northern hemisphere. The derived Cl/Si mass ratio is 0.0057 ± 0.001, which for an assumed Si abundance of 24.6 wt% corresponds to 0.14 ± 0.03 wt% Cl. The abundance of Cl is a factor of 2.9 ± 1.3 higher in the north polar region (>80°N) than at latitudes 0-60°N, a latitudinal variation similar to that observed for Na. Our reported Cl abundances are consistent with measured bulk concentrations of neutron-absorbing elements on Mercury, particularly those observed at high northern latitudes. The Cl/K ratio on Mercury is chondritic, indicating a limited impact history akin to that of Mars, which accreted rapidly. Hypotheses for the origin of Mercury's high metal-to-silicate ratio must be able to reproduce Mercury's observed elemental abundances, including Cl. Chlorine is also an important magmatic volatile, and its elevated abundance in the northern polar region of Mercury indicates that it could have played a role in the production, ascent, and eruption of flood volcanic material in this region. We have identified several candidate primary mineralogical hosts for Cl on Mercury, including the halide minerals lawrencite (FeCl2), sylvite (KCl), and halite (NaCl), as well as Cl-bearing alkali sulfides. Amphiboles, micas, apatite, and aqueously deposited halides, in contrast, may be ruled out as mineralogical hosts of Cl on Mercury.

  18. FURTHER OBSERVATIONS OF PLANETS AND QUASI-STELLAR RADIO SOURCES AT 3 MM.

    DTIC Science & Technology

    EXTRATERRESTRIAL RADIO WAVES), (* MERCURY ( PLANET ), (*RADIO ASTRONOMY, EXTRATERRESTRIAL RADIO WAVES), PLANETARY ATMOSPHERES, SKY BRIGHTNESS, ANTENNAS...EPHEMERIDES, ASTROPHYSICS, JUPITER( PLANET ), VENUS( PLANET ), BRIGHTNESS, ATMOSPHERIC TEMPERATURE, INTENSITY, MEASUREMENT.

  19. A measurement of the shape of the solar disk: The solar quadrupole moment, the solar octopole moment, and the advance of perihelion of the planet mercury

    SciTech Connect

    Lydon, T.J.; Sofia, S.

    1996-01-01

    The Solar Disk Sextant experiment has measured the solar angular diameter for a variety of solar latitudes. Combined with solar surface angular rotation data, the solar quadrupole moment {ital J}{sub 2} and the solar octopole moment {ital J}{sub 4} have been derived first by assuming constant internal angular rotation on cylinders and then by assuming constant internal angular rotation on cones. We have derived values of 1.8{times}10{sup {minus}7} for {ital J}{sub 2} and 9.8{times}10{sup {minus}7} for {ital J}{sub 4}. We conclude with a discussion of errors and address the prediction of general relativity for the rate of advance of perihelion of the planet Mercury. {copyright} {ital 1996 The American Physical Society.}

  20. The Planet Mercury Surface Spectroscopy and Analysis from the Kuiper Airborne Observatory and Analysis and Modeling to Determine Surface Composition

    NASA Technical Reports Server (NTRS)

    Sprague, Ann

    1997-01-01

    We had two successful flights to observe Mercury from the Kuiper Airborne Observatory (KAO) using High-efficiency Infrared Faint-Object Grating Spectrograph (HIFOGS). Flights were May 8, 1995 (eastern elongation) and July 6, 1995 (western elongation) For the observations one half of the primary mirror was covered to prevent sunlight from entering the telescope. All equipment and the airplane and its crew performed well. These flights were historical firsts for the KAO and for spectroscopy of Mercury in that it was the first time any spectroscopic observations of Mercury from above the Earth's atmosphere had been made. It was the first time the KAO had been used to @bserve an object less than 30 degrees from the Sun. Upon completion of the basic data reduction it became obvious that extensive modeling and analysis would be required to understand the data. It took three years of a graduate student's time and part time the PI to do the thermal modeling and the spectroscopic analysis. This resulted in a lengthy publication. A copy of this publication is attached and has all the data obtained in both KAO flights and the results clearly presented. Notable results are: (1) The observations found an as yet unexplained 5 micron emission enhancement that we think may be a real characteristic of Mercury's surface but could have an instrumental cause; (2) Ground-based measurements or an emission maximum at 7.7 microns were corroborated. The chemical composition of Mercury's surface must be feldspathic in order to explain spectra features found in the data obtained during the KAO flights.

  1. The Planet Mercury Surface Spectroscopy and Analysis from the Kuiper Airborne Observatory and Analysis and Modeling to Determine Surface Composition

    NASA Technical Reports Server (NTRS)

    Sprague, Ann

    1997-01-01

    We had two successful flights to observe Mercury from the Kuiper Airborne Observatory (KAO) using High-efficiency Infrared Faint-Object Grating Spectrograph (HIFOGS). Flights were May 8, 1995 (eastern elongation) and July 6, 1995 (western elongation) For the observations one half of the primary mirror was covered to prevent sunlight from entering the telescope. All equipment and the airplane and its crew performed well. These flights were historical firsts for the KAO and for spectroscopy of Mercury in that it was the first time any spectroscopic observations of Mercury from above the Earth's atmosphere had been made. It was the first time the KAO had been used to @bserve an object less than 30 degrees from the Sun. Upon completion of the basic data reduction it became obvious that extensive modeling and analysis would be required to understand the data. It took three years of a graduate student's time and part time the PI to do the thermal modeling and the spectroscopic analysis. This resulted in a lengthy publication. A copy of this publication is attached and has all the data obtained in both KAO flights and the results clearly presented. Notable results are: (1) The observations found an as yet unexplained 5 micron emission enhancement that we think may be a real characteristic of Mercury's surface but could have an instrumental cause; (2) Ground-based measurements or an emission maximum at 7.7 microns were corroborated. The chemical composition of Mercury's surface must be feldspathic in order to explain spectra features found in the data obtained during the KAO flights.

  2. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  3. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  4. The Study of Mercury

    NASA Astrophysics Data System (ADS)

    Prockter, Louise M.; Bedini, Peter D.

    2010-01-01

    When the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft enters orbit about Mercury in March 2011 it will begin a new phase in an age-old scientific study of the innermost planet. Despite being visible to the unaided eye, Mercury's proximity to the Sun makes it extremely difficult to observe from Earth. Nonetheless, over the centuries man has pursued a quest to understand the elusive planet, and has teased out information about its motions in the sky, its relation to the other planets, and its physical characteristics. A great leap was made in our understanding of Mercury when the Mariner 10 spacecraft flew past it three times in the mid-1970s, providing a rich set of close-up observations. Now, three decades later, The MESSENGER spacecraft has also visited the planet three times, and is poised to add significantly to the study with a year-long orbital observation campaign.

  5. Uncratered Area on Mercury

    NASA Image and Video Library

    1999-10-08

    A dark, smooth, relatively uncratered area on Mercury was photographed two hours after NASA Mariner 10 flew by the planet. The prominent, sharp crater with a central peak is 30 kilometers 19 miles across.

  6. Mercury's exosphere: observations during MESSENGER's First Mercury flyby.

    PubMed

    McClintock, William E; Bradley, E Todd; Vervack, Ronald J; Killen, Rosemary M; Sprague, Ann L; Izenberg, Noam R; Solomon, Sean C

    2008-07-04

    During MESSENGER's first Mercury flyby, the Mercury Atmospheric and Surface Composition Spectrometer measured Mercury's exospheric emissions, including those from the antisunward sodium tail, calcium and sodium close to the planet, and hydrogen at high altitudes on the dayside. Spatial variations indicate that multiple source and loss processes generate and maintain the exosphere. Energetic processes connected to the solar wind and magnetospheric interaction with the planet likely played an important role in determining the distributions of exospheric species during the flyby.

  7. Mercury Solar Transit

    NASA Image and Video Library

    2016-05-09

    The planet Mercury is seen in silhouette, lower center of image, as it transits across the face of the sun, Monday, May 9, 2016, as viewed from Boyertown, Pennsylvania. Mercury passes between Earth and the sun only about 13 times a century, with the previous transit taking place in 2006. Photo Credit: (NASA/Bill Ingalls)

  8. Mercury Solar Transit

    NASA Image and Video Library

    2016-05-09

    The planet Mercury is seen in silhouette, lower third of image, as it transits across the face of the sun Monday, May 9, 2016, as viewed from Boyertown, Pennsylvania. Mercury passes between Earth and the sun only about 13 times a century, with the previous transit taking place in 2006. Photo Credit: (NASA/Bill Ingalls)

  9. Mercury Solar Transit

    NASA Image and Video Library

    2016-05-09

    The planet Mercury is seen in silhouette, lower left of image, as it transits across the face of the sun, Monday, May 9, 2016, as viewed from Boyertown, Pennsylvania. Mercury passes between Earth and the sun only about 13 times a century, with the previous transit taking place in 2006. Photo Credit: (NASA/Bill Ingalls)

  10. Mercury Solar Transit

    NASA Image and Video Library

    2016-05-09

    The planet Mercury is seen in silhouette, lower left, as it transits across the face of the sun Monday, May 9, 2016, as viewed from Boyertown, Pennsylvania. Mercury passes between Earth and the sun only about 13 times a century, with the previous transit taking place in 2006. Photo Credit: (NASA/Bill Ingalls)

  11. Project Mercury - Monument

    NASA Image and Video Library

    1966-11-11

    S66-59963 (9 Nov. 1966) --- Monument at Pad 14 honoring Project Mercury. The Arabic number seven represents the seven original astronauts. The other figure is the astronomical symbol of the Planet Mercury. In background is the Gemini-12 Agena Target Docking Vehicle atop its Atlas launch vehicle at Cape Kennedy, Florida. Photo credit: NASA

  12. Possible Disintegrating Planet Artist Concept

    NASA Image and Video Library

    2012-05-21

    This artist concept depicts a comet-like tail of a possible disintegrating super Mercury-size planet candidate as it transits, or crosses, its parent star, named KIC 12557548. The results are based on data from NASA Kepler mission.

  13. Planets' magnetic environments

    SciTech Connect

    Lanzerotti, L.J.; Uberoi, C.

    1989-02-01

    The magnetospheres of Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and comets and the heliomagnetosphere are examined. The orientations of the planetary spin and magnetic axes, the size of the magnetospheres, and the magnetic properties and the radio emissions of the planets are compared. Results from spacecraft studies of the planets are included. Plans for the Voyager 2 mission and its expected study of the Neptune magnetosphere are considered.

  14. Planetary science: Mercury's mysteries start to unfold

    NASA Astrophysics Data System (ADS)

    Stevenson, David J.

    2012-05-01

    The origin of the planet Mercury has been a continuing puzzle. Data from NASA's MESSENGER space probe, combined with ground-based observations, are delivering information on the planet's structure and evolution.

  15. Nonrelativistic Contribution to Mercury's Perihelion Precession.

    ERIC Educational Resources Information Center

    Price, Michael P.; Rush, William F.

    1979-01-01

    Presents a calculation of the precession of the perihelion of Mercury due to the perturbations from the outer planets. The time-average effect of each planet is calculated by replacing that planet with a ring of linear mass density equal to the mass of the planet divided by the circumference of its orbit. (Author/GA)

  16. Nonrelativistic Contribution to Mercury's Perihelion Precession.

    ERIC Educational Resources Information Center

    Price, Michael P.; Rush, William F.

    1979-01-01

    Presents a calculation of the precession of the perihelion of Mercury due to the perturbations from the outer planets. The time-average effect of each planet is calculated by replacing that planet with a ring of linear mass density equal to the mass of the planet divided by the circumference of its orbit. (Author/GA)

  17. Terrestrial planet formation

    PubMed Central

    Righter, K.; O’Brien, D. P.

    2011-01-01

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (∼106 y), followed by planetesimals to embryos (lunar to Mars-sized objects; few × 106 y), and finally embryos to planets (107–108 y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids. PMID:21709256

  18. Terrestrial planet formation.

    PubMed

    Righter, K; O'Brien, D P

    2011-11-29

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (~10(6) y), followed by planetesimals to embryos (lunar to Mars-sized objects; few 10(6) y), and finally embryos to planets (10(7)-10(8) y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids.

  19. Unlocking the Secrets of Mercury

    NASA Image and Video Library

    Of all the rocky planets, Mercury is the smallest and densest, the one with the oldest surface, and the one with the largest daily surface temperature variations. It is also the least explored! Joi...

  20. MESSENGER: Exploring the Innermost Planet

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.

    2011-12-01

    One of Earth's closest planetary neighbors, Mercury remained comparatively unexplored for the more than three decades that followed the three flybys of the innermost planet by the Mariner 10 spacecraft in 1974-75. Mariner 10 imaged 45% of Mercury's surface at about 1 km/pixel average resolution, confirmed Mercury's anomalously high bulk density and implied large fractional core size, discovered Mercury's internal magnetic field, documented that H and He are present in the planet's tenuous exosphere, and made the first exploration of Mercury's magnetosphere and solar wind environment. Ground-based astronomers later reported Na, K, and Ca in Mercury's exosphere; the presence of deposits in the floors of polar craters having radar characteristics best matched by water ice; and strong evidence from the planet's forced libration amplitude that Mercury has a fluid outer core. Spacecraft exploration of Mercury resumed with the selection for flight, under NASA's Discovery Program, of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. Launched in 2004, MESSENGER flew by the innermost planet three times in 2008-2009 en route to becoming the first spacecraft to orbit Mercury in March of this year. MESSENGER's first chemical remote sensing measurements of Mercury's surface indicate that the planet's bulk silicate fraction differs from those of the other inner planets, with a low-Fe surface composition intermediate between basalts and ultramafic rocks and best matched among terrestrial rocks by komatiites. Moreover, surface materials are richer in the volatile constituents S and K than predicted by most planetary formation models. Global image mosaics and targeted high-resolution images (to resolutions of 10 m/pixel) reveal that Mercury experienced globally extensive volcanism, including large expanses of plains emplaced as flood lavas and widespread examples of pyroclastic deposits likely emplaced during explosive eruptions of volatile

  1. Mercury Solar Transit

    NASA Image and Video Library

    2016-05-09

    Boyertown Area High School astronomy teacher Peter Detterline prepares high powered binoculars with a solar filter so that his students may view the planet Mercury as it transits across the face of the sun , Monday, May 9, 2016, Boyertown Area High School, Boyertown, Pennsylvania. Mercury passes between Earth and the sun only about 13 times a century, with the previous transit taking place in 2006. Photo Credit: (NASA/Bill Ingalls)

  2. Mercury Solar Transit

    NASA Image and Video Library

    2016-05-09

    Boyertown Area High School students, 12th grader Bransen Mackey, left, and 11th grader Nick Cioppi wear solar safety glasses and attempt to see the planet Mercury as it transits across the face of the sun, Monday, May 9, 2016, Boyertown, Pennsylvania. Mercury passes between Earth and the sun only about 13 times a century, with the previous transit taking place in 2006. Photo Credit: (NASA/Bill Ingalls)

  3. Mercury Solar Transit

    NASA Image and Video Library

    2016-05-09

    Boyertown Area High School 12th grade student Ben Maurer uses his smartphone and a photographers lens with a solar filter to make a photograph of the planet Mercury transitting the sun, Monday, May 9, 2016, Boyertown area High School, Boyertown, Pennsylvania. Mercury passes between Earth and the sun only about 13 times a century, with the previous transit taking place in 2006. Photo Credit: (NASA/Bill Ingalls)

  4. Mercury Solar Transit

    NASA Image and Video Library

    2016-05-09

    Boyertown Area High School 12th grade student Jay Hallman looks through a photographers lens and solar filter to see the planet Mercury as it transits across the face of the sun , Monday, May 9, 2016, Boyertown area High School, Boyertown, Pennsylvania. Mercury passes between Earth and the sun only about 13 times a century, with the previous transit taking place in 2006. Photo Credit: (NASA/Bill Ingalls)

  5. Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.

    1999-01-01

    Among the major discoveries made by the Mariner 10 mission to the inner planets was the existence of an intrinsic magnetic field at Mercury with a dipole moment of approx. 300 nT R(sup 3, sub M). This magnetic field is sufficient to stand off the solar wind at an altitude of about 1 R(sub M) (i.e. approx. 2439 km). Hence, Mercury possesses a 'magnetosphere' from which the so]ar wind plasma is largely excluded and within which the motion of charged particles is controlled by the planetary magnetic field. Despite its small size relative to the magnetospheres of the other planets, a Mercury orbiter mission is a high priority for the space physics community. The primary reason for this great interest is that Mercury unlike all the other planets visited thus far, lacks a significant atmosphere; only a vestigial exosphere is present. This results in a unique situation where the magnetosphere interacts directly with the outer layer of the planetary crust (i.e. the regolith). At all of the other planets the topmost regions of their atmospheres become ionized by solar radiation to form ionospheres. These planetary ionospheres then couple to electrodynamically to their magnetospheres or, in the case of the weakly magnetized Venus and Mars, directly to the solar wind. This magnetosphere-ionosphere coupling is mediated largely through field-aligned currents (FACs) flowing along the magnetic field lines linking the magnetosphere and the high-latitude ionosphere. Mercury is unique in that it is expected that FACS will be very short lived due to the low electrical conductivity of the regolith. Furthermore, at the earth it has been shown that the outflow of neutral atmospheric species to great altitudes is an important source of magnetospheric plasma (following ionization) whose composition may influence subsequent magnetotail dynamics. However, the dominant source of plasma for most of the terrestrial magnetosphere is the 'leakage'of solar wind across the magnetopause and more

  6. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Cratering histories of the intercrater plains. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The intercrater plains of Mercury and the Moon are defined, in part, by their high densities of small craters. The crater size frequency statistics presented in this chapter may help constrain the relative ages and origins of these surfaces. To this end, the effects of common geologic processes on crater frequency statistics are compared with the diameter frequency distributions of the intercrater regions of the Moon and Mercury. Such analyses may determine whether secondary craters dominate the distribution at small diameters, and whether volcanic plains or ballistic deposits form the intercrater surface. Determining the mass frequency distribution and flux of the impacting population is a more difficult problem. The necessary information such as scaling relationships between projectile energy and crater diameter, the relative fluxes of solar system objects, and the absolute ages of surface units is model dependent and poorly constrained, especially for Mercury.

  7. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Cratering histories of the intercrater plains. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The intercrater plains of Mercury and the Moon are defined, in part, by their high densities of small craters. The crater size frequency statistics presented in this chapter may help constrain the relative ages and origins of these surfaces. To this end, the effects of common geologic processes on crater frequency statistics are compared with the diameter frequency distributions of the intercrater regions of the Moon and Mercury. Such analyses may determine whether secondary craters dominate the distribution at small diameters, and whether volcanic plains or ballistic deposits form the intercrater surface. Determining the mass frequency distribution and flux of the impacting population is a more difficult problem. The necessary information such as scaling relationships between projectile energy and crater diameter, the relative fluxes of solar system objects, and the absolute ages of surface units is model dependent and poorly constrained, especially for Mercury.

  8. Innermost Planets of the Solar System

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The appearance and characteristics of Mercury and Venus as evening and morning stars are discussed. Inferior and superior conjunction are defined. The motions, phases, and planetary dynamics of the two planets are compared with those of the earth and moon.

  9. On-board calibration of the spectral response functions of the Advanced Baseline Imager's thermal IR channels by observation of the planet Mercury

    NASA Astrophysics Data System (ADS)

    Bremer, James C.

    2010-09-01

    The Advanced Baseline Imager (ABI) will image Earth in 16 spectral channels, including 10 thermal IR (TIR) channels. The instantaneous field of view (IFOV) of each TIR detector element is (56 μrad)2. The ABI has an onboard fullaperture blackbody, the Internal Calibration Target (ICT), used in conjunction with deep space looks to calibrate the ABI's TIR channels. The ICT is only observed over a small range of temperatures and at one specific pair of reflection angles from the ABI's two scan mirrors. The sunlit area on Mercury's surface underfills the IFOV's of the ABI's TIR channels, but has a much higher range of characteristic temperatures than the ICT, so its radiation is weighted more strongly toward shorter wavelengths. Comparison of a TIR channel's responses to the ICT and to Mercury provides a sensitive means to evaluate variations in spectral response functions among detector elements, across the ABI's field of regard, and among instruments on different satellites. Observations of Mercury can also verify co-registration among the ABI's atmospheric absorption channels that do not observe features on Earth's surface. The optimal conditions for viewing Mercury typically occur during one or two intervals of a few weeks each year when it traverses the ABI's FOR (-10.5o < declination < +10.5o) with an elongation angle from the Sun of at least 20.5o.

  10. Exploring Mercury Tail

    NASA Image and Video Library

    2008-08-26

    As the MESSENGER spacecraft approached Mercury, the UVVS field of view was scanned across the planet's exospheric "tail," which is produced by the solar wind pushing Mercury's exosphere (the planet's extremely thin atmosphere) outward. This figure, recently published in Science magazine, shows a map of the distribution of sodium atoms as they stream away from the planet (see PIA10396); red and yellow colors represent a higher abundance of sodium than darker shades of blue and purple, as shown in the colored scale bar, which gives the brightness intensity in units of kiloRayleighs. The escaping atoms eventually form a comet-like tail that extends in the direction opposite that of the Sun for many planetary radii. The small squares outlined in black correspond to individual measurements that were used to create the full map. These measurements are the highest-spatial-resolution observations ever made of Mercury's tail. In less than six weeks, on October 6, 2008, similar measurements will be made during MESSENGER's second flyby of Mercury. Comparing the measurements from the two flybys will provide an unprecedented look at how Mercury's dynamic exosphere and tail vary with time. Date Acquired: January 14, 2008. http://photojournal.jpl.nasa.gov/catalog/PIA11076

  11. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed dri-fi paths for energetic particles and, hence, no radiation belts; the characteristic time scales for wave propagation and convective transport are short possibly coupling kinetic and fluid modes; magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to directly impact the dayside regolith; inductive currents in Mercury's interior should act to modify the solar In addition, Mercury's magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionosphere. This lack of an ionosphere is thought to be the underlying reason for the brevity of the very intense, but short lived, approx. 1-2 min, substorm-like energetic particle events observed by Mariner 10 in Mercury's magnetic tail. In this seminar, we review what we think we know about Mercury's magnetosphere and describe the MESSENGER science team's strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic magnetosphere.

  12. Planets, planets everywhere

    NASA Astrophysics Data System (ADS)

    1999-09-01

    The authors, an international team led by Harm Habing, from Leiden University (The Netherlands), wanted to know if stars belonging to a particular class were more likely than others to form planets. In our own Solar System planets formed out of a disc of small particles of dust, so every star surrounded by such a disc is a potential planet-forming star. The astronomers therefore chose a sample of 84 nearby stars, all of them very common and in the most stable phase of their lives - the 'main sequence' - but of different ages. Which ones would have discs? Discs are difficult to see because they emit very faintly; only a few had been positively detected so far. Using ESA's highly sensitive infrared space observatory, ISO, the international team found that 15 stars in their sample did have a disc. Then they analysed the ages of the stars: it turned out that most of those younger than 400 million years had discs, while the great majority of the older ones did not. "We show for the first time that the presence of a disc around a main sequence star depends strongly on the star's age. Why do those above a precise age not have discs? We searched for clues in our own Solar System, and realised that it was just when the Sun was that age (about 400 million years) that planets were forming", Habing says. In our Solar System, several facts demonstrate that very soon after the formation of the planets the disc orbiting the Sun disappeared. Some evidence comes, for instance, from Moon craters. These 'scars' on the lunar surface were made while the planets were completing their formation phase and the Sun was losing its own disc of debris, during the 'clean-up phase' of the Solar System. The newly-born planets scattered the remaining planetesimals, which were ejected from the system, fell into the Sun or collided with other large bodies - such as the Moon. The age determinations of lunar rocks brought back by the Apollo missions prove that all this happened when the Sun was 300 to

  13. Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Deeg, Hans; Belmonte, Juan Antonio; Aparicio, Antonio

    2012-03-01

    Participants; Preface; Acknowledgements; 1. Extrasolar planet detection methods Laurance R. Doyle; 2. Statistical properties of exoplanets Stéphane Udry; 3. Characterizing extrasolar planets Timothy M. Brown; 4. From clouds to planet systems: formation and evolution of stars and planets Günther Wuchterl; 5. Abundances in stars with extrasolar planetary systems Garik Israelian; 6. Brown dwarfs: the bridge between stars and planets Rafael Rebolo; 7. The perspective: a panorama of the Solar System Agustín Sánchez-Lavega; 8. Habitable planets around the Sun and other stars James F. Kasting; 9. Biomarkers of extrasolar planets and their observability Franck Selsis, Jimmy Paillet and France Allard; Index.

  14. Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Deeg, Hans; Belmonte, Juan Antonio; Aparicio, Antonio

    2007-10-01

    Participants; Preface; Acknowledgements; 1. Extrasolar planet detection methods Laurance R. Doyle; 2. Statistical properties of exoplanets Stéphane Udry; 3. Characterizing extrasolar planets Timothy M. Brown; 4. From clouds to planet systems: formation and evolution of stars and planets Günther Wuchterl; 5. Abundances in stars with extrasolar planetary systems Garik Israelian; 6. Brown dwarfs: the bridge between stars and planets Rafael Rebolo; 7. The perspective: a panorama of the Solar System Agustín Sánchez-Lavega; 8. Habitable planets around the Sun and other stars James F. Kasting; 9. Biomarkers of extrasolar planets and their observability Franck Selsis, Jimmy Paillet and France Allard; Index.

  15. 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…

  16. 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…

  17. The tectonics of Mercury

    NASA Technical Reports Server (NTRS)

    Melosh, H. J.; Mckinnon, W. B.

    1988-01-01

    The probable tectonic history of Mercury and the relative sequence of events are discussed on the basis of data collected by the Mariner-10 spacecraft. Results indicate that Mercury's tectonic activity was confined to its early history; its endogenic activity was principally due to a small change in the shape of its lithosphere, caused by tidal despinning, and a small change in area caused by shrinkage due to cooling. Exogenic processes, in particular the impact activity, have produced more abundant tectonic features. Many features associated with the Caloris basin are due to loading of Mercury's thick lithosphere by extrusive lavas or subsidence due to magma withdrawal. It is emphasized that tectonic features observed on Mercury yield insight into the earliest tectonic events on planets like Mars and, perhaps, the earth, where subsequent events obscured or erased the most ancient tectonic records.

  18. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    United States Postal Service Vice President of Finance Steve Masse, left, and NASA Mercury Astronaut Scott Carpenter, unveil two USPS stamps to commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  19. Mercury's Dynamic Magnetic Tail

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2010-01-01

    The Mariner 10 and MESSENGER flybys of Mercury have revealed a magnetosphere that is likely the most responsive to upstream interplanetary conditions of any in the solar system. The source of the great dynamic variability observed during these brief passages is due to Mercury's proximity to the Sun and the inverse proportionality between reconnection rate and solar wind Alfven Mach number. However, this planet's lack of an ionosphere and its small physical dimensions also contribute to Mercury's very brief Dungey cycle, approx. 2 min, which governs the time scale for internal plasma circulation. Current observations and understanding of the structure and dynamics of Mercury's magnetotail are summarized and discussed. Special emphasis will be placed upon such questions as: 1) How much access does the solar wind have to this small magnetosphere as a function of upstream conditions? 2) What roles do heavy planetary ions play? 3) Do Earth-like substorms take place at Mercury? 4) How does Mercury's tail respond to extreme solar wind events such coronal mass ejections? Prospects for progress due to advances in the global magnetohydrodynamic and hybrid simulation modeling and the measurements to be taken by MESSENGER after it enters Mercury orbit on March 18, 2011 will be discussed.

  20. Taxonomy of the extrasolar planet.

    PubMed

    Plávalová, Eva

    2012-04-01

    When a star is described as a spectral class G2V, we know that the star is similar to our Sun. We know its approximate mass, temperature, age, and size. When working with an extrasolar planet database, it is very useful to have a taxonomy scale (classification) such as, for example, the Harvard classification for stars. The taxonomy has to be easily interpreted and present the most relevant information about extrasolar planets. I propose an extrasolar planet taxonomy scale with four parameters. The first parameter concerns the mass of an extrasolar planet in the form of units of the mass of other known planets, where M represents the mass of Mercury, E that of Earth, N Neptune, and J Jupiter. The second parameter is the planet's distance from its parent star (semimajor axis) described in a logarithm with base 10. The third parameter is the mean Dyson temperature of the extrasolar planet, for which I established four main temperature classes: F represents the Freezing class, W the Water class, G the Gaseous class, and R the Roasters class. I devised one additional class, however: P, the Pulsar class, which concerns extrasolar planets orbiting pulsar stars. The fourth parameter is eccentricity. If the attributes of the surface of the extrasolar planet are known, we are able to establish this additional parameter where t represents a terrestrial planet, g a gaseous planet, and i an ice planet. According to this taxonomy scale, for example, Earth is 1E0W0t, Neptune is 1N1.5F0i, and extrasolar planet 55 Cnc e is 9E-1.8R1.

  1. Terminator View of Mercury

    NASA Image and Video Library

    2017-09-27

    Date acquired: May 05, 2014 Today's color image features both Mercury's terminator and limb. The terminator is the striking separation of night and day on Mercury. It is seen in this image with the change from dark, on the left of the image, to light. Mercury's limb is also captured, as we can see the edge between sunlit Mercury and space. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. During the first two years of orbital operations, MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington 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

  2. Reference Atmosphere for Mercury

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.

    2002-01-01

    We propose that Ar-40 measured in the lunar atmosphere and that in Mercury's atmosphere is due to current diffusion into connected pore space within the crust. Higher temperatures at Mercury, along with more rapid loss from the atmosphere will lead to a smaller column abundance of argon at Mercury than at the Moon, given the same crustal abundance of potassium. Because the noble gas abundance in the Hermean atmosphere represents current effusion, it is a direct measure of the crustal potassium abundance. Ar-40 in the atmospheres of the planets is a measure of potassium abundance in the interiors, since Ar-40 is a product of radiogenic decay of K-40 by electron capture with the subsequent emission of a 1.46 eV gamma-ray. Although the Ar-40 in the Earth's atmosphere is expected to have accumulated since the late bombardment, Ar-40 in the atmospheres of Mercury and the Moon is eroded quickly by photoionization and electron impact ionization. Thus, the argon content in the exospheres of the Moon and Mercury is representative of current effusion rather than accumulation over the lifetime of the planet.

  3. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Fonda, Mark (Technical Monitor)

    2002-01-01

    Modern theories of star and planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. The most detailed models of planetary growth are based upon observations of planets and smaller bodies within our own Solar System and of young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed, and the methods that are being used and planned for detecting and characterizing extrasolar planets are reviewed.

  4. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Fonda, Mark (Technical Monitor)

    2002-01-01

    Modern theories of star and planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. The most detailed models of planetary growth are based upon observations of planets and smaller bodies within our own Solar System and of young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed, and the methods that are being used and planned for detecting and characterizing extrasolar planets are reviewed.

  5. Migrating Planets

    NASA Astrophysics Data System (ADS)

    Murray, N.; Hansen, B.; Holman, M.; Tremaine, S.

    1998-01-01

    A planet orbiting in a disk of planetesimals can experience an instability in which it migrates to smaller orbital radii. Resonant interactions between the planet and planetesimals remove angular momentum from the planetesimals, increasing their eccentricities. Subsequently, the planetesimals either collide with or are ejected by the planet, reducing the semimajor axis of the planet. If the surface density of planetesimals exceeds a critical value, corresponding to 0.03 solar masses of gas inside the orbit of Jupiter, the planet will migrate inward a large distance. This instability may explain the presence of Jupiter-mass objects in small orbits around nearby stars.

  6. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1997-01-01

    Modern theories of star and planet formation, which are based upon observations of the Solar System and of young stars and their environments, predict that most single stars should have rocky planets in orbit about them; the frequency of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Models for the formation of the giant planets found in recent radial velocity searches are discussed.

  7. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1998-01-01

    An overview of current theories of star and planet formation is presented. These models are based upon observations of the Solar System and of young stars and their environments. They predict that rocky planets should form around most single stars, although it is possible that in some cases such planets are lost to orbital decay within the protoplanetary disk. The frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates.

  8. Momument at Pad 14 honoring Project Mercury

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Momument at Pad 14 honoring Project Mercury. The Arabic number 7 represents the seven original astronauts. The other figure is the astronomical symbol of the Planet Mercury. In background is the Gemini 12 Agena Target Docking Vehicle atop its Atlas launch vehicle at Cape Kennedy, Florida.

  9. Terrestrial Planet Geophysics

    NASA Astrophysics Data System (ADS)

    Phillips, R. J.

    2008-12-01

    Terrestrial planet geophysics beyond our home sphere had its start arguably in the early 1960s, with Keith Runcorn contending that the second-degree shape of the Moon is due to convection and Mariner 2 flying past Venus and detecting no planetary magnetic field. Within a decade, in situ surface geophysical measurements were carried out on the Moon with the Apollo program, portions of the lunar magnetic and gravity fields were mapped, and Jack Lorell and his colleagues at JPL were producing spherical harmonic gravity field models for Mars using tracking data from Mariner 9, the first spacecraft to orbit another planet. Moreover, Mariner 10 discovered a planetary magnetic field at Mercury, and a young Sean Solomon was using geological evidence of surface contraction to constrain the thermal evolution of the innermost planet. In situ geophysical experiments (such as seismic networks) were essentially never carried out after Apollo, although they were sometimes planned just beyond the believability horizon in planetary mission queues. Over the last three decades, the discipline of terrestrial planet geophysics has matured, making the most out of orbital magnetic and gravity field data, altimetric measurements of surface topography, and the integration of geochemical information. Powerful constraints are provided by tectonic and volcanic information gleaned from surface images, and the engagement of geologists in geophysical exercises is actually quite useful. Accompanying these endeavors, modeling techniques, largely adopted from the Earth Science community, have become increasingly sophisticated and have been greatly enhanced by the dramatic increase in computing power over the last two decades. The future looks bright with exciting new data sets emerging from the MESSENGER mission to Mercury, the promise of the GRAIL gravity mission to the Moon, and the re-emergence of Venus as a worthy target for exploration. Who knows? With the unflagging optimism and persistence

  10. Accumulation of the planets

    NASA Technical Reports Server (NTRS)

    Wetherill, G. W.

    1987-01-01

    In modeling the accumulation of planetesimals into planets, it is appropriate to distinguish between two stages: an early stage, during which approximately 10 km diameter planetesimals accumulate locally to form bodies approximate 10 to the 25th g in mass; and a later stage in which the approximately 10 to the 25th g planetesimals accumulate into the final planets. In the terrestrial planet region, an initial planetesimal swarm corresponding to the critical mass of dust layer gravitational instabilities is considered. In order to better understand the accumulation history of Mercury-sized bodies, 19 Monte-Carlo simulations of terrestrial planet growth were calculated. A Monte Carlo technique was used to investigate the orbital evolution of asteroidal collision debris produced interior to 2.6 AU. It was found that there are two regions primarily responsible for production of Earth-crossing meteoritic material and Apollo objects. The same techniques were extended to include the origin of Earth-approaching asteroidal bodies. It is found that these same two resonant mechanisms predict a steady-state number of Apollo-Amor about 1/2 that estimated based on astronomical observations.

  11. MESSENGER'S First Flyby of Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. An overview of the MESSENGER mission and its January 14th close flyby of Mercury will be provided. Primary science objectives and the science instrumentation will be described. Initial results from MESSENGER'S first flyby on January 14th, 2008 will be discussed with an emphasis on the magnetic field and charged particle measurements.

  12. Mercury: Beethoven Quadrangle, H-7

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Mercury: Computer Photomosaic of the Beethoven Quadrangle, H-7 The Beethoven Quadrangle, named for the 19th century classical German composer, lies in Mercury's Equatorial Mercator located between longitude 740 to 1440. The Mariner 10 spacecraft imaged the region during its initial flyby of the planet. The Image Processing Lab at NASA's Jet Propulsion Laboratory produced this photomosaic using computer software and techniques developed for use in processing planetary data. The images used to construct the Beethoven Quadrangle were taken as Mariner 10 flew passed Mercury. The Mariner 10 spacecraft was launched in 1974. The spacecraft took images of Venus in February 1974 on the way to three encounters with Mercury in March and September 1974 and March 1975. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth and the Moon during its mission. The Mariner 10 Mission was managed by the Jet Propulsion Laboratory for NASA's Office of Space Science in Washington, D.C.

  13. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    Daughters of NASA astronaut Alan Shepard, Laura Shepard Churchley, left, Alice Wackermann and Julie Jenkins, right, speak during an unveiling ceremony of two USPS stamps that commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  14. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    Daughters of NASA astronaut Alan Shepard, Laura Shepard Churchley, standing left, Alice Wackermann and Julie Jenkins, standing right, speak during an unveiling ceremony of two USPS stamps that commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  15. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    NASA Administrator Charles Boldin speaks during an unveiling ceremony of two USPS stamps that commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  16. Mercury's sodium exosphere

    NASA Astrophysics Data System (ADS)

    Leblanc, F.; Johnson, R. E.

    2003-08-01

    Mercury's neutral sodium exosphere is simulated using a comprehensive 3D Monte Carlo model following sodium atoms ejected from Mercury's surface by thermal desorption, photon stimulated desorption, micro-meteoroid vaporization and solar wind sputtering. The evolution of the sodium surface density with respect to Mercury's rotation and its motion around the Sun is taken into account by considering enrichment processes due to surface trapping of neutrals and ions and depletion of the sodium available for ejection from the surfaces of grains. The change in the sodium exosphere is calculated during one Mercury year taking into account the variations in the solar radiation pressure, the photo-ionization frequency, the solar wind density, the photon and meteoroid flux intensities, and the surface temperature. Line-of-sight column densities at different phase angles, the supply rate of new sodium, average neutral and ion losses over a Mercury year, surface density distribution and the importance of the different processes of ejection are discussed in this paper. The sodium surface density distribution is found to become significantly nonuniform from day to night sides, from low to high latitudes and from morning to afternoon because of rapid depletion of sodium atoms in the surfaces of grains mainly driven by thermal depletion. The shape of the exosphere, as it would be seen from the Earth, changes drastically with respect to Mercury's heliocentric position. High latitude column density maxima are related to maxima in the sodium surface concentration at high latitudes in Mercury's surface and are not necessarily due to solar wind sputtering. The ratio between the sodium column density on the morning side of Mercury's exosphere and the sodium column density on the afternoon side is consistent with the conclusions of Sprague et al. (1997, Icarus 129, 506-527). The model, which has no fitting parameters, shows surprisingly good agreement with recent observations of Potter et

  17. To Mercury dynamics

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.; Ferrandiz, J. M.

    obtain new and accurate data about dynamics and structure of this planet (Anselmi et al., 2001). There are also some evaluations of moments of inertia Mercury and its core: C/(mR^2)=0.35, C_m /C=0.5± 0.07, (Peal, 1996). Here C and C_m are the moments of inertia of the full Mercury and of its core, m and R is a mass and a mean radius of Mercury. Based on two methods, we consider the rotation of Mercury in the gravitational field of the Sun. First method of perturbation has been effectively applied to the construction of a rotational theory of the Earth for its models as two or three layer celestial body moving in gravitational fields of the Moon, Sun and planets in wide set of papers ranging in 1999-2001 years of Ferrandiz J.M. and Getino J.(2001). Some generalization of this Hamiltonian formalism on the case of cavity (core) with arbitrary dynamical and geometrical oblateness has been obtained in a paper (Barkin, Ferrandiz, 2001). Another method is an analytical method of construction of the resonant rotational motion of synchronous satellites and Mercury, considered as non-spherical rigid bodies. This method has been applied earlier to construction of an analytical theory of rotation of the Moon considered as rigid non-spherical body (Barkin, 1989). Here we modified these methods to apply them to the study of the resonant rotation of a two-layer Mercury. By this we use very effective for the application of perturbation methods and dynamical geometrical illustration of canonical equations in Andoyer and Poincare variables. Main resonant properties of Mercury motion were been described first as generalized Cassini's laws (Colombo, 1966). But Colombo and some anothers scientists (Peal, 1969; Beletskii, 1972; Ward, 1975 and oth.) considered Mercury as rigid non-spherical body sometimes taking into account tidal deformation. Here we have been obtained and formulated these laws and their generalization for a two-layer model of Mercury. On the next step we have evaluated

  18. Mercury: The Kuiper Melt

    NASA Image and Video Library

    2017-09-27

    Date acquired: April 05, 2013 This striking image of Kuiper shows the crater in a new perspective. This image highlights the crater's smooth impact melt and central peaks. Kuiper, first seen by Mariner 10, is an easily identifiable feature on Mercury's surface due to its bright rays, similar to Hokusai. This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. During the first two years of orbital operations, MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

  19. A sub-Mercury-sized exoplanet.

    PubMed

    Barclay, Thomas; Rowe, Jason F; Lissauer, Jack J; Huber, Daniel; Fressin, François; Howell, Steve B; Bryson, Stephen T; Chaplin, William J; Désert, Jean-Michel; Lopez, Eric D; Marcy, Geoffrey W; Mullally, Fergal; Ragozzine, Darin; Torres, Guillermo; Adams, Elisabeth R; Agol, Eric; Barrado, David; Basu, Sarbani; Bedding, Timothy R; Buchhave, Lars A; Charbonneau, David; Christiansen, Jessie L; Christensen-Dalsgaard, Jørgen; Ciardi, David; Cochran, William D; Dupree, Andrea K; Elsworth, Yvonne; Everett, Mark; Fischer, Debra A; Ford, Eric B; Fortney, Jonathan J; Geary, John C; Haas, Michael R; Handberg, Rasmus; Hekker, Saskia; Henze, Christopher E; Horch, Elliott; Howard, Andrew W; Hunter, Roger C; Isaacson, Howard; Jenkins, Jon M; Karoff, Christoffer; Kawaler, Steven D; Kjeldsen, Hans; Klaus, Todd C; Latham, David W; Li, Jie; Lillo-Box, Jorge; Lund, Mikkel N; Lundkvist, Mia; Metcalfe, Travis S; Miglio, Andrea; Morris, Robert L; Quintana, Elisa V; Stello, Dennis; Smith, Jeffrey C; Still, Martin; Thompson, Susan E

    2013-02-28

    Since the discovery of the first exoplanets, it has been known that other planetary systems can look quite unlike our own. Until fairly recently, we have been able to probe only the upper range of the planet size distribution, and, since last year, to detect planets that are the size of Earth or somewhat smaller. Hitherto, no planets have been found that are smaller than those we see in the Solar System. Here we report a planet significantly smaller than Mercury. This tiny planet is the innermost of three that orbit the Sun-like host star, which we have designated Kepler-37. Owing to its extremely small size, similar to that of the Moon, and highly irradiated surface, the planet, Kepler-37b, is probably rocky with no atmosphere or water, similar to Mercury.

  20. Extreme Planets

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This artist's concept depicts the pulsar planet system discovered by Aleksander Wolszczan in 1992. Wolszczan used the Arecibo radio telescope in Puerto Rico to find three planets - the first of any kind ever found outside our solar system - circling a pulsar called PSR B1257+12. Pulsars are rapidly rotating neutron stars, which are the collapsed cores of exploded massive stars. They spin and pulse with radiation, much like a lighthouse beacon. Here, the pulsar's twisted magnetic fields are highlighted by the blue glow.

    All three pulsar planets are shown in this picture; the farthest two from the pulsar (closest in this view) are about the size of Earth. Radiation from charged pulsar particles would probably rain down on the planets, causing their night skies to light up with auroras similar to our Northern Lights. One such aurora is illustrated on the planet at the bottom of the picture.

    Since this landmark discovery, more than 160 extrasolar planets have been observed around stars that are burning nuclear fuel. The planets spotted by Wolszczan are still the only ones around a dead star. They also might be part of a second generation of planets, the first having been destroyed when their star blew up. The Spitzer Space Telescope's discovery of a dusty disk around a pulsar might represent the beginnings of a similarly 'reborn' planetary system.

  1. Extreme Planets

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This artist's concept depicts the pulsar planet system discovered by Aleksander Wolszczan in 1992. Wolszczan used the Arecibo radio telescope in Puerto Rico to find three planets - the first of any kind ever found outside our solar system - circling a pulsar called PSR B1257+12. Pulsars are rapidly rotating neutron stars, which are the collapsed cores of exploded massive stars. They spin and pulse with radiation, much like a lighthouse beacon. Here, the pulsar's twisted magnetic fields are highlighted by the blue glow.

    All three pulsar planets are shown in this picture; the farthest two from the pulsar (closest in this view) are about the size of Earth. Radiation from charged pulsar particles would probably rain down on the planets, causing their night skies to light up with auroras similar to our Northern Lights. One such aurora is illustrated on the planet at the bottom of the picture.

    Since this landmark discovery, more than 160 extrasolar planets have been observed around stars that are burning nuclear fuel. The planets spotted by Wolszczan are still the only ones around a dead star. They also might be part of a second generation of planets, the first having been destroyed when their star blew up. The Spitzer Space Telescope's discovery of a dusty disk around a pulsar might represent the beginnings of a similarly 'reborn' planetary system.

  2. Space plasma physics research progress 1987-1990 - Mars, Venus, and Mercury

    SciTech Connect

    Luhmann, J.G. )

    1991-01-01

    Theoretical and observational studies of space plasma physics at the inner planets, Mars, Venus, and Mercury are reviewed. Emphasis is placed on the solar wind interactions and aeronomy (upper neutral atmospheres and ionospheres) of these planets. 206 refs.

  3. On the Edge of Mercury

    NASA Image and Video Library

    2017-09-28

    In this image, Mercury's horizon cuts a striking edge against the stark blackness of space. On the right, sunlight harshly brings the landscape into relief while on the left, the surface is shrouded in the darkness of night. This image was acquired as part of MDIS's limb imaging campaign. Once per week, MDIS captures images of Mercury's limb, with an emphasis on imaging the southern hemisphere limb. These limb images provide information about Mercury's shape and complement measurements of topography made by the Mercury Laser Altimeter (MLA) of Mercury's northern hemisphere. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. In the mission's more than three years of orbital operations, MESSENGER has acquired over 250,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington 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

  4. Mercury and Your Health

    MedlinePlus

    ... the Risk of Exposure to Mercury Learn About Mercury What is Mercury What is Metallic mercury? Toxicological Profile ToxFAQs Mercury Resources CDC’s National Biomonitoring Program Factsheet on Mercury ...

  5. [Mercury poisoning].

    PubMed

    Bensefa-Colas, L; Andujar, P; Descatha, A

    2011-07-01

    Mercury is a widespread heavy metal with potential severe impacts on human health. Exposure conditions to mercury and profile of toxicity among humans depend on the chemical forms of the mercury: elemental or metallic mercury, inorganic or organic mercury compounds. This article aims to reviewing and synthesizing the main knowledge of the mercury toxicity and its organic compounds that clinicians should know. Acute inhalation of metallic or inorganic mercury vapours mainly induces pulmonary diseases, whereas chronic inhalation rather induces neurological or renal disorders (encephalopathy and interstitial or glomerular nephritis). Methylmercury poisonings from intoxicated food occurred among some populations resulting in neurological disorders and developmental troubles for children exposed in utero. Treatment using chelating agents is recommended in case of symptomatic acute mercury intoxication; sometimes it improves the clinical effects of chronic mercury poisoning. Although it is currently rare to encounter situations of severe intoxication, efforts remain necessary to decrease the mercury concentration in the environment and to reduce risk on human health due to low level exposure (dental amalgam, fish contamination by organic mercury compounds…). In case of occupational exposure to mercury and its compounds, some disorders could be compensated in France. Clinicians should work with toxicologists for the diagnosis and treatment of mercury intoxication.

  6. Mercury's Complex Exosphere: Results from MESSENGER's Third Flyby

    NASA Technical Reports Server (NTRS)

    Vervack, Ronald J., Jr.; McClintock, William E.; Killen, Rosemary M.; Sprague, Ann L.; Anderson, Brian J.; Burger, Matthew H.; Bradley, E. Todd; Mouawad, Nelly; Solomon, Sean C.; Izenberg, Noam R.

    2010-01-01

    During MESSENGER's third flyby of Mercury, the Mercury Atmospheric and Surface Composition Spectrometer detected emission from ionized calcium concentrated 1 to 2 Mercury radii tailward of the planet. This measurement provides evidence for tailward magnetospheric convection of photoions produced inside the magnetosphere. Observations of neutral sodium, calcium, and magnesium above the planet's north and south poles reveal attitude distributions that are distinct for each species. A two-component sodium distribution and markedly different magnesium distributions above the two poles are direct indications that multiple processes control the distribution of even single species in Mercury's exosphere,

  7. Mercury's complex exosphere: results from MESSENGER's third flyby.

    PubMed

    Vervack, Ronald J; McClintock, William E; Killen, Rosemary M; Sprague, Ann L; Anderson, Brian J; Burger, Matthew H; Bradley, E Todd; Mouawad, Nelly; Solomon, Sean C; Izenberg, Noam R

    2010-08-06

    During MESSENGER's third flyby of Mercury, the Mercury Atmospheric and Surface Composition Spectrometer detected emission from ionized calcium concentrated 1 to 2 Mercury radii tailward of the planet. This measurement provides evidence for tailward magnetospheric convection of photoions produced inside the magnetosphere. Observations of neutral sodium, calcium, and magnesium above the planet's north and south poles reveal altitude distributions that are distinct for each species. A two-component sodium distribution and markedly different magnesium distributions above the two poles are direct indications that multiple processes control the distribution of even single species in Mercury's exosphere.

  8. Outer Planets

    NASA Image and Video Library

    Did you know that through NASA’s various satellite missions we have learned more about these planetary bodies in recent years than we knew collectively since we started to study our planets? Throu...

  9. Planet formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    1993-01-01

    Models of planetary formation are developed using the present single example of a planetary system, supplemented by limited astrophysical observations of star-forming regions and circumstellar disks. The solar nebula theory and the planetesimal hypothesis are discussed. The latter is found to provide a viable theory of the growth of the terrestrial planets, the cores of the giant planets, and the smaller bodies present in the solar system. The formation of solid bodies of planetary size should be a common event, at least around young stars which do not have binary companions orbiting at planetary distances. Stochastic impacts of large bodies provide sufficient angular momentum to produce the obliquities of the planets. The masses and bulk compositions of the planets can be understood in a gross sense as resulting from planetary growth within a disk whose temperature and surface density decreased with distance from the growing sun.

  10. Origin and composition of Mercury

    NASA Technical Reports Server (NTRS)

    Lewis, John S.

    1988-01-01

    The predictions of the expected range of composition of Mercury at the time of its formation made on the basis of a suite of condensation-accretion models of Mercury spanning a range of condensation temperature and accretion sampling functions appropriate to Mercury are examined. It is concluded that these compositonal models can, if modified to take into account the nonselective loss of most of the silicate component of the planet during accretion, provide compositional predictions for the Weidenschilling (1978, 1980) mechanism for the accretion of a metal-rich Mercury. The silicate portion would, in this case, contain 3.6 to 4.5 percent alumina, roughly 1 percent of alkali oxides, and between 0.5 and 6 percent FeO.

  11. Characterization of Mercury's Space Environment

    NASA Astrophysics Data System (ADS)

    Laurenza, Monica; Storini, Marisa; Diego, Piero; Massetti, Stefano

    2015-04-01

    Data from the Helios spacecraft have been revised to identify different solar wind conditions (interplanetary magnetic field intensity, solar wind density, velocity and temperature) at Mercury's location, as they induce critcal changes in the Hermean environment. In particular, the weak magnetic field of the planet and the increasing weight of the interplanetary magnetic field (IMF) BX component at Mercury's orbit, introduce critical differences in the Mercury magnetosphere, such as a strong north-south asymmetry. Different geometries of the Mercury's magnetosphere are also calculated as response to the different solar wind conditions through aToffoletto-Hill modified model (Massetti et al., 2007). Results allow to compute the cutoff rigidities, in order to estimate the energetic charged particle transmission through the Hermean magnetosphere to the specific location of the BepiColombo spacecraft Work partly supported by the Italian Space Agency

  12. Mercury Project

    NASA Image and Video Library

    1959-04-27

    Astronaut L. Gordon Cooper, Jr., one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The MA-9 mission, boosted by the Mercury-Atlas launch vehicle, was the last flight of the Mercury Project. The Faith 7 spacecraft orbited the Earth 22 times in 1-1/2 days.

  13. Reorientation Histories of the Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Keane, J. T.; Matsuyama, I.

    2016-12-01

    The nature of how a planet spins is controlled by the planet's inertia tensor. In a minimum energy rotation state, planets spin about the maximum principal axis of inertia. Yet, the orientation of this axis is not often constant with time. The redistribution of mass within a planet due to both interior processes (e.g. convection, intrusive volcanism) and surface processes (e.g. extrusive volcanism, impacts) can significantly alter the planet's inertia tensor, resulting in the reorientation of the planet. This form of reorientation is also known as true polar wander. Reorientation can directly alter the topography and gravity field of a planet, generate tectonic stresses, change the insolation geometry (affecting climate and volatile stability), and modify the orientation of the planet's magnetic field. Yet, despite its significance, the reorientation histories of many planets is not well constrained. In this work, we present a new technique for using spacecraft-derived, orbital gravity measurements to directly quantify how individual large geologic features reoriented Mercury, Venus, the Moon, and Mars. When coupled with the geologic record for these respective planets, this enables us to determine the reorientation history for each planet. These mark the first comprehensive, multi-episode reorientation chronologies for these planets. The reorientation histories for the Moon and Mercury are similar; the orientation of both planets is strongly controlled by the presence of large remnant bulges (tidal/rotational for the Moon, and likely thermal for Mercury), but significantly modulated by subsequent, large impacts and volcanic events—resulting in 15° of total reorientation after their formation. Mars experienced larger reorientation due to the formation of the Tharsis rise, punctuated by smaller reorientation events from large impacts. Lastly, Venus's diminutive remnant figure and large volcanic edifices result in the largest possible reorientation events, but the

  14. The Low-Degree Shape of Mercury

    NASA Astrophysics Data System (ADS)

    Perry, M. E.; Neumann, G. A.; Mazarico, E.; Hauck, S. A., II; Solomon, S. C.; Zuber, M. T.; Smith, D. E.; Phillips, R. J.; Margot, J. L.; Johnson, C. L.; Ernst, C. M.; Oberst, J.

    2015-12-01

    The shape of Mercury, particularly when combined with its geoid, provides clues to the planet's internal structure, thermal evolution, and rotational history. Twenty-five million elevation measurements of the northern hemisphere, acquired by the Mercury Laser Altimeter on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft, were combined with 378 occultation measurements of radio-frequency signals from the spacecraft in the planet's southern hemisphere to reveal the low-degree shape of Mercury. We solved for the spherical-harmonic coefficients through degree and order 128 and found that Mercury's mean radius is 2439.36±0.02 km. The offset between the planet's centers of mass and figure is negligible (40±40 m) along the polar axis and modest (140±50 m) in the equatorial plane. Mercury's spherical-harmonic shape spectrum is dominated by degree 2, and the planet's first-order shape is that of a triaxial ellipsoid with semimajor axes a, b, and c. The polar radius, c, is 1.65 km less than (a+b)/2, and the equatorial difference, a-b, is 1.25 km. The long axis is rotated 15° west of Mercury's dynamically defined principal axis. Mercury's geoid is similarly dominated by degree 2 and well described by a triaxial ellipsoid. The degree-2 geoid and shape are highly correlated, but the power spectral density of the geoid at degree 2 is only 1% of its shape counterpart, implying substantial compensation of elevation variations on a global scale and that Mercury is not in hydrostatic equilibrium.

  15. Compressibility of Mercury's Dayside Magnetosphere

    NASA Astrophysics Data System (ADS)

    Zhong, J.; Wan, W.; Wei, Y.; Slavin, J. A.; Raines, J. M.; Rong, Z.; Chai, L.; Han, X.

    2016-12-01

    Mercury's comparatively weak intrinsic magnetic field, together with the strong solar wind forcing in the inner heliosphere, creates a small and highly dynamic magnetosphere. Unlike other planets in the solar system, Mercury is experiencing significant variations of solar wind forcing along its large eccentric orbit. With 12 Mercury years of data from MESSENGER, we demonstrate that Mercury's distance from the Sun has a great effect on the size of the dayside magnetosphere that is much larger than the temporal variations. The mean solar wind standoff distance was found to be about 0.27 Mercury radii (RM) closer to the Mercury at perihelion than at aphelion. At perihelion the subsolar magnetopause can be compressed below 1.2 RM of 2.5% of the time. The relationship between the average magnetopause standoff distance and heliocentric distance suggests that on average the effects of the erosion process appears to counter balance those of induction in Mercury's interior at perihelion. However, at aphelion, where solar wind pressure is lower and Alfvénic Mach number is higher, the effects of induction appear dominant.

  16. The evolution of the moon and the terrestrial planets

    NASA Technical Reports Server (NTRS)

    Toksoez, M. N.; Johnston, D. H.

    1977-01-01

    The thermal evolutions of the Moon, Mars, Venus, and Mercury were calculated theoretically starting from cosmochemical condensation models. An assortment of geological, geochemical, and geophysical data were used to constrain both the present day temperature and the thermal histories of the planets' interiors. Such data imply that the planets were heated during or shortly after formation and that all the terrestrial planets started their differentiations early in their history.

  17. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie E.; McCoy, J. Torin; Garcia, Hector D.; James, John T.

    2009-01-01

    Many of the operational and payload lighting units used in various spacecraft contain elemental mercury. If these devices were damaged on-orbit, elemental mercury could be released into the cabin. Although there are plans to replace operational units with alternate light sources, such as LEDs, that do not contain mercury, mercury-containing lamps efficiently produce high quality illumination and may never be completely replaced on orbit. Therefore, exposure to elemental mercury during spaceflight will remain possible and represents a toxicological hazard. Elemental mercury is a liquid metal that vaporizes slowly at room temperature. However, it may be completely vaporized at the elevated operating temperatures of lamps. Although liquid mercury is not readily absorbed through the skin or digestive tract, mercury vapors are efficiently absorbed through the respiratory tract. Therefore, the amount of mercury in the vapor form must be estimated. For mercury releases from lamps that are not being operated, we utilized a study conducted by the New Jersey Department of Environmental Quality to calculate the amount of mercury vapor expected to form over a 2-week period. For longer missions and for mercury releases occurring when lamps are operating, we conservatively assumed complete volatilization of the available mercury. Because current spacecraft environmental control systems are unable to remove mercury vapors, both short-term and long-term exposures to mercury vapors are possible. Acute exposure to high concentrations of mercury vapors can cause irritation of the respiratory tract and behavioral symptoms, such as irritability and hyperactivity. Chronic exposure can result in damage to the nervous system (tremors, memory loss, insomnia, etc.) and kidneys (proteinurea). Therefore, the JSC Toxicology Group recommends that stringent safety controls and verifications (vibrational testing, etc.) be applied to any hardware that contains elemental mercury that could yield

  18. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie E.; McCoy, J. Torin; Garcia, Hector D.; James, John T.

    2009-01-01

    Many of the operational and payload lighting units used in various spacecraft contain elemental mercury. If these devices were damaged on-orbit, elemental mercury could be released into the cabin. Although there are plans to replace operational units with alternate light sources, such as LEDs, that do not contain mercury, mercury-containing lamps efficiently produce high quality illumination and may never be completely replaced on orbit. Therefore, exposure to elemental mercury during spaceflight will remain possible and represents a toxicological hazard. Elemental mercury is a liquid metal that vaporizes slowly at room temperature. However, it may be completely vaporized at the elevated operating temperatures of lamps. Although liquid mercury is not readily absorbed through the skin or digestive tract, mercury vapors are efficiently absorbed through the respiratory tract. Therefore, the amount of mercury in the vapor form must be estimated. For mercury releases from lamps that are not being operated, we utilized a study conducted by the New Jersey Department of Environmental Quality to calculate the amount of mercury vapor expected to form over a 2-week period. For longer missions and for mercury releases occurring when lamps are operating, we conservatively assumed complete volatilization of the available mercury. Because current spacecraft environmental control systems are unable to remove mercury vapors, both short-term and long-term exposures to mercury vapors are possible. Acute exposure to high concentrations of mercury vapors can cause irritation of the respiratory tract and behavioral symptoms, such as irritability and hyperactivity. Chronic exposure can result in damage to the nervous system (tremors, memory loss, insomnia, etc.) and kidneys (proteinurea). Therefore, the JSC Toxicology Group recommends that stringent safety controls and verifications (vibrational testing, etc.) be applied to any hardware that contains elemental mercury that could yield

  19. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Krimigis, Stamatios M.; Acuna, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Koehn, Patrick L.; Korth, Haje; Levi, Stefano; Mauk, Barry H.; Solomon, Sean C.; Zurbuchen, Thomas H.

    2005-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet s miniature magnetosphere since the brief flybys of Mariner 10. Mercury s magnetosphere is unique in many respects. The magnetosphere of Mercury is among the smallest in the solar system; its magnetic field typically stands off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed drift paths for energetic particles and, hence, no radiation belts. The characteristic time scales for wave propagation and convective transport are short and kinetic and fluid modes may be coupled. Magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to impact directly the regolith. Inductive currents in Mercury s interior may act to modify the solar wind interaction by resisting changes due to solar wind pressure variations. Indeed, observations of these induction effects may be an important source of information on the state of Mercury s interior. In addition, Mercury s magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionospheric layer. This lack of an ionosphere is probably the underlying reason for the brevity of the very intense, but short-lived, - 1-2 min, substorm-like energetic particle events observed by Mariner 10 during its first traversal of Mercury s magnetic tail. Because of Mercury s proximity to the sun, 0.3 - 0.5 AU, this magnetosphere experiences the most extreme driving forces in the solar system. All of these factors are expected to produce complicated interactions involving the exchange and re-cycling of neutrals and ions between the solar wind, magnetosphere, and regolith. The electrodynamics of Mercury s magnetosphere are expected to be equally complex, with strong forcing by the solar wind, magnetic reconnection at the magnetopause and in the tail, and the pick-up of planetary ions all

  20. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    From left, NASA Deputy Director, Planetary Science Division, Science Mission Directorate, Jim Adams, NASA Kennedy Space Center Director of Education and External Relations Cheryl Hurst, United States Postal Service Vice President of Finance Steve Masse, NASA Mercury Astronaut Scott Carpenter, NASA Administrator Charles Boldin, Daughters of NASA astronaut Alan Shepard, Alice Wackermann, Laura Shepard Churchley, and Julie Jenkins, and NASA Kennedy Space Center Director Robert Cabana pose for a photograph during an unveiling ceremony of two USPS stamps that commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  1. Microlensing Planets

    NASA Astrophysics Data System (ADS)

    Gould, Andrew

    The theory and practice of microlensing planet searches is developed in a systematic way, from an elementary treatment of the deflection of light by a massive body to a thorough discussion of the most recent results. The main concepts of planetary microlensing, including microlensing events, finite-source effects, and microlens parallax, are first introduced within the simpler context of point-lens events. These ideas are then applied to binary (and hence planetary) lenses and are integrated with concepts specific to binaries, including caustic topologies, orbital motion, and degeneracies, with an emphasis on analytic understanding. The most important results from microlensing planet searches are then reviewed, with emphasis both on understanding the historical process of discovery and the means by which scientific conclusions were drawn from light-curve analysis. Finally, the future prospects of microlensing planets searches are critically evaluated. Citations to original works provide the reader with multiple entry points into the literature.

  2. The Microlensing Planet Search Program of the WFIRST Mission

    NASA Astrophysics Data System (ADS)

    Bennett, David P.

    2011-01-01

    The recently Decadal Survey report, "New Worlds, New Horizons in Astronomy and Astrophysics" recommends a new mission called WFIRST as its top ranked large space mission for the next decade. The WFIRST mission is to have two major science programs that will drive the design requirements: a dark energy program and a microlensing planet search program. WFIRST's microlensing planet search program will provide a statistical census of exoplanets with masses greater than one tenth of an Earth mass and orbital separations ranging from 0.5AU to infinity. This includes analogs to all the Solar System's planets except for Mercury, as well as most types of planets predicted by planet formation theories. In combination with Kepler's census of planets in shorter period orbits, WFIRST's planet search program will provide a complete statistical census of the planets that populate our Galaxy.

  3. The Microlensing Planet Search Program of the WFIRST Mission

    NASA Astrophysics Data System (ADS)

    Bennett, David P.

    2010-10-01

    The recently Decadal Survey report, "New Worlds, New Horizons in Astronomy and Astrophysics" recommends a new mission called WFIRST as its top ranked large space mission for the next decade. The WFIRST mission is to have two major science programs that will drive the design requirements: a dark energy program and a microlensing planet search program. WFIRST's microlensing planet search program will provide a statistical census of exoplanets with masses greater than one tenth of an Earth mass and orbital separations ranging from 0.5AU to infinity. This includes analogs to all the Solar System's planets except for Mercury, as well as most types of planets predicted by planet formation theories. In combination with Kepler's census of planets in shorter period orbits, WFIRST's planet search program will provide a complete statistical census of the planets that populate our Galaxy.

  4. Thermal Evolution of Mercury

    NASA Astrophysics Data System (ADS)

    Multhaup, K.

    2008-09-01

    A 1D thermal evolution model of Mercury is presented. Refer to Fig. 1 for a sketch. Mercury is assumed to consist of a dense, initially entirely fluid iron-rich core surrounded by a convecting silicate mantle with a conducting immobile layer on top. Heating is provided by radiogenic decay. As the planet evolves, an inner core may freeze out and the mantle may differentiate by forming a basaltic crust. As our current knowledge of Mercury provides poor constraints on key parameters including mantle rheology, sulphur contents of the core or radiogenic heat sources, a broad range of contrasting values is used to create thermal histories of the innermost planet of the solar system. The proposed evolutions of mantle temperature, core adiabat and stagnant lid thickness provide starting points for considerations pertaining to a possible core dynamo, interior and exterior heat flows, characteristics of the mantle-crust system, impact events and the Hermian gravity field. For given parameters, mantle convection is likely to have continued until the present day. Inner cores of pure iron—either completely frozen out or engulfed in a spherical liquid shell—are obtained only if "wet" mantle rheology is assumed. Results from earlier and current studies and data obtained by Mariner 10 or ground-based studies are used to evaluate the various model outcomes, but insight expected from the BepiColombo or MESSENGER missions is required to further limit the parameter space. The present-day ratio of Mercury's inner and outer cores as determined by the core sulphur content is shown in Fig. 2 for an initially volatile-rich (A) and refractory-rich (B) mantle-crust system. Trends in results characterizing the present-day Hermian mantlecrust system are shown in Fig. 3.

  5. BepiColombo: Exploring Mercury

    NASA Astrophysics Data System (ADS)

    Geelen, K.; Novara, M.; Fugger, S.; Benkhoff, J.

    2014-04-01

    BepiColombo is an interdisciplinary mission to explore Mercury, the planet closest to the sun, carried out jointly between the European Space Agency and the Japanese Aerospace Exploration Agency. The mission consists of two orbiters dedicated to the detailed study of the planet and of its magnetosphere, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). The MPO is ESA's scientific contribution to the mission and comprises 11 science instruments. It is a three-axis-stabilized, nadir-pointing spacecraft which will be placed in a polar orbit with a period of approximately 2.3 hours, a periapsis of 480 km and an apoapsis of 1500 km, providing excellent spatial resolution over the entire planet surface. The interplanetary transfer is performed by an Electric Propulsion Module, which is jettisoned when Mercury is reached. It will set off in July 2016 on a journey to the smallest and least explored terrestrial planet in our Solar System. When it arrives at Mercury in January 2024, it will endure temperatures in excess of 350 °C and gather data during its 1 year nominal mission, with a possible 1-year extension. The difficulty of reaching, surviving and operating in the harsh environment of a planet so close to the sun, makes BepiColombo one of the most challenging planetary projects undertaken by ESA so far. A range of major challenges need to be overcome to enable the mission including the electric propulsion system, development of a new Multi-Layer Insulation able to withstand the high temperatures, an original solar panel design, stringent pointing requirements to be maintained in extreme conditions varying from a solar flux of 10 solar constants to eclipse conditions etc. The scientific payload of both spacecraft will provide the detailed information necessary to understand the origin and evolution of the planet itself and its surrounding environment. The scientific objectives focus on a global characterization of Mercury through the

  6. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Geologic map analyses: Correlation of geologic and cratering histories. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Geologic map analyses are expanded, beginning with a discussion of particular regions which may illustrate volcanic and ballistic plains emplacement on Mercury. Major attention is focused on the surface history of Mercury through discussion of the areal distribution of plains and craters and the paleogeologic maps of the first quadrant. A summary of the lunar intercrater plains formation similarly interrelates the information from the Moon's geologic and cratering histories.

  7. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Geologic map analyses: Correlation of geologic and cratering histories. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Geologic map analyses are expanded, beginning with a discussion of particular regions which may illustrate volcanic and ballistic plains emplacement on Mercury. Major attention is focused on the surface history of Mercury through discussion of the areal distribution of plains and craters and the paleogeologic maps of the first quadrant. A summary of the lunar intercrater plains formation similarly interrelates the information from the Moon's geologic and cratering histories.

  8. Mariner 10 mercury encounter.

    PubMed

    Dunne, J A

    1974-07-12

    Mariner 10's closet approach to Mercury on 29 March 1974 occurred on the dark side of the planet at a range of approximately 700 kilometers. The spacecraft trajectory passed through the shadows of both the sun and Earth. Experiments conducted included magnetic fields, plasma and charged particle studies of the solar wind interaction region, television photography, extreme ultraviolet spectroscopy of the atmosphere, the detection of infrared thermal radiation from the surface, and a dual-frequency radio occultation in search of an ionosphere.

  9. 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.

  10. The Origin of Mercury

    NASA Astrophysics Data System (ADS)

    Benz, W.; Anic, A.; Horner, J.; Whitby, J. A.

    Mercury's unusually high mean density has always been attributed to special circumstances that occurred during the formation of the planet or shortly thereafter, and due to the planet's close proximity to the Sun. The nature of these special circumstances is still being debated and several scenarios, all proposed more than 20 years ago, have been suggested. In all scenarios, the high mean density is the result of severe fractionation occurring between silicates and iron. It is the origin of this fractionation that is at the centre of the debate: is it due to differences in condensation temperature and/or in material characteristics (e.g. density, strength)? Is it because of mantle evaporation due to the close proximity to the Sun? Or is it due to the blasting off of the mantle during a giant impact?

  11. Mercury - Surface composition from the reflection spectrum.

    NASA Technical Reports Server (NTRS)

    Mccord, T. B.; Adams, J. B.

    1972-01-01

    The reflection spectrum for the integral disk of the planet Mercury was measured and was found to have a constant positive slope from 0.32 to 1.05 micrometers, except for absorption features in the infrared. The reflectivity curve matches closely the curve for the lunar upland and mare regions. Thus, the surface of Mercury is probably covered with a lunar-like soil rich in dark glasses of high iron and titanium content. Pyroxene is probably the dominant mafic mineral.

  12. Mercury: the dark-side temperature.

    PubMed

    Murdock, T L; Ney, E P

    1970-10-30

    The planet Mercury was observed before, during, and after the inferior conjunctions of 29 September 1969 and 9 May 1970 at wavelengths of 3.75, 4.75, 8.6, and 12 microns. The average dark-side temperature is 111 degrees +/- 3 degrees K. The thermal inertia of the surface required to fit this temperature is close to that for the moon and indicates that Mercury and the moon have very similar top surface layers.

  13. Mercury: surface composition from the reflection spectrum.

    PubMed

    McCord, T B; Adams, J B

    1972-11-17

    The reflection spectrum for the integral disk of the planet Mercury was measured and was found to have a constant positive slope from 0.32 to 1.05 micrometers, except for absorption features in the infrared. The reflectivity curve matches closely the curve for the lunar upland and mare regions. Thus, the surface of Mercury is probably covered with a lunar-like soil rich in dark glasses of high iron and titanium content. Pyroxene is probably the dominant mafic mineral.

  14. Binary Planets

    NASA Astrophysics Data System (ADS)

    Ryan, Keegan; Nakajima, Miki; Stevenson, David J.

    2014-11-01

    Can a bound pair of similar mass terrestrial planets exist? We are interested here in bodies with a mass ratio of ~ 3:1 or less (so Pluto/Charon or Earth/Moon do not qualify) and we do not regard the absence of any such discoveries in the Kepler data set to be significant since the tidal decay and merger of a close binary is prohibitively fast well inside of 1AU. SPH simulations of equal mass “Earths” were carried out to seek an answer to this question, assuming encounters that were only slightly more energetic than parabolic (zero energy). We were interested in whether the collision or near collision of two similar mass bodies would lead to a binary in which the two bodies remain largely intact, effectively a tidal capture hypothesis though with the tidal distortion being very large. Necessarily, the angular momentum of such an encounter will lead to bodies separated by only a few planetary radii if capture occurs. Consistent with previous work, mostly by Canup, we find that most impacts are disruptive, leading to a dominant mass body surrounded by a disk from which a secondary forms whose mass is small compared to the primary, hence not a binary planet by our adopted definition. However, larger impact parameter “kissing” collisions were found to produce binaries because the dissipation upon first encounter was sufficient to provide a bound orbit that was then rung down by tides to an end state where the planets are only a few planetary radii apart. The long computational times for these simulation make it difficult to fully map the phase space of encounters for which this outcome is likely but the indications are that the probability is not vanishingly small and since planetary encounters are a plausible part of planet formation, we expect binary planets to exist and be a non-negligible fraction of the larger orbital radius exoplanets awaiting discovery.

  15. Got Mercury?

    NASA Astrophysics Data System (ADS)

    Meyers, Valerie E.; McCoy, Torin J.; Garcia, Hector D.; James, John T.

    2010-09-01

    Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed by the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may vaporize completely when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. We estimated mercury vapor releases from stowed lamps during missions lasting ≤ 30 days, whereas we conservatively assumed complete vaporization from stowed lamps during missions lasting > 30 days and from operating lamps regardless of mission duration. The toxicity of mercury and its lack of removal have led Johnson Space Center’s Toxicology Group to recommend stringent safety controls and verifications for hardware containing elemental mercury that could yield airborne mercury vapor concentrations > 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting ≤ 30 days, or concentrations > 0.01 mg/m3 for exposures lasting > 30 days.

  16. Mpo - the Bepicolombo Mercury Planetary Orbiter.

    NASA Astrophysics Data System (ADS)

    Benkhoff, J.

    2008-09-01

    Introduction: BepiColombo is an interdisciplinary mission to explore the planet Mercury through a partnership between ESA and Japan's Aerospace Exploration Agency (JAXA). From their dedicated orbits two spacecrafts, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO), will be studying the planet and its environment Both orbiter will be launched together on an ARIANE 5. The launch is foreseen for Summer 2014 with arrival in Summer 2020. Solar electric propulsion will be used for the journey to Mercury. In November 2004, the BepiColombo scientific payload has been officially approved. Payload of BepiColombo: The MPO scientific payload comprises eleven instruments/instrument packages; the MMO scientific payload consists of five instruments/instrument packages. Together, the scientific payload of both spacecraft will provide the detailed information necessary to understand Mercury and its magnetospheric environment and to find clues to the origin and evolution of a planet close to its parent star. The MPO will focus on a global characterization of Mercury through the investigation of its interior, surface, exosphere and magnetosphere. In addition, it will be testing Einstein's theory of general relativity. Major effort was put into optimizing the scientific return by defining the payload complement such that individual measurements can be interrelated and complement each other. A detailed overview of the status of BepiColombo will be given with special emphasis on the MPO and its payload complement. BepiColombo factsheet BepiColombo is Europe's first mission to Mercury, the innermost planet of the Solar System, and ESA's first science mission in collaboration with Japan. A satellite 'duo' - consisting of an orbiter for planetary investigation and one for magnetospheric studies - Bepi- Colombo will reach Mercury after a six-year journey towards the inner Solar System, to make the most extensive and detailed study of the planet ever performed

  17. Mercury Project

    NASA Image and Video Library

    1961-07-21

    Astronaut Virgil Gus Grissom awaits America's second marned space mission, Mercury-Redstone 4 (MR-4) on July 21, 1961. During the 15-minute suborbital flight, the Liberty Bell 7 Mercury spacecraft reached an altitude of 118 miles and traveled 303 miles downrange. It was the fourth flight of the Mercury-Redstone launch vehicle (MR-4), developed by Dr. Wernher von Braun and the rocket team in Huntsville, Alabama.

  18. Mercury Project

    NASA Image and Video Library

    1961-01-01

    Ham, a three-year-old chimpanzee, in the spacesuit he would wear for the second Mercury- Redstone (MR-2) suborbital test flight in January, 1961. NASA used chimpanzees and other primates to test the Mercury capsule before launching the fisrt American astronaut, Alan Shepard, in May 1961. The Mercury capsule rode atop a modified Redstone rocket, developed by Dr. Wernher von Braun and the German Rocket Team in Huntsville, Alabama.

  19. Mercury Project

    NASA Image and Video Library

    1959-01-01

    Dr. Wernher von Braun, Director of the Army Ballistic Missile Agency's (ABMA) Development Operations Division, poses with the original Mercury astronauts in ABMA's Fabrication Laboratory during a 1959 visit. Inspecting Mercury-Redstone hardware are from left to right, Alan Shepard, Donald Deke Slayton, Virgil Gus Grissom, von Braun, Gordon Cooper, Wally Schirra, John Glenn, and Scott Carpenter. Project Mercury officially began October 7, 1958 as the United States' first manned space program.

  20. Optical system design and integration of the mercury laser altimeter.

    PubMed

    Ramos-Lzquierdo, Luis; Scott, V Stanley; Schmidt, Stephen; Britt, Jamie; Mamakos, William; Trunzo, Raymond; Cavanaugh, John; Miller, Roger

    2005-03-20

    The Mercury Laser Altimeter (MLA), developed for the 2004 MESSENGER mission to Mercury, is designed to measure the planet's topography by laser ranging. A description of the MLA optical system and its measured optical performance during instrument-level and spacecraft-level integration and testing are presented.

  1. Optical System Design and Integration of the Mercury Laser Altimeter

    NASA Technical Reports Server (NTRS)

    Ramos-Izquierdo, Luis; Scott, V. Stanley, III; Schmidt, Stephen; Britt, Jamie; Mamakos, William; Trunzo, Raymond; Cavanaugh, John; Miller, Roger

    2005-01-01

    The Mercury Laser Altimeter (MLA). developed for the 2004 MESSENGER mission to Mercury, is designed to measure the planet's topography via laser ranging. A description of the MLA optical system and its measured optical performance during instrument-level and spacecraft-level integration and testing are presented.

  2. How Tiny Collisions Shape Mercury

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-07-01

    If space rocks are unpleasant to encounter, space dust isnt much better. Mercurys cratered surface tells of billions of years of meteoroid impacts but its thin atmosphere is what reveals its collisional history with smaller impactors. Now new research is providing a better understanding of what were seeing.Micrometeoroids Ho!The inner solar system is bombarded by micrometeoroids, tiny particles of dust (on the scale of a tenth of a millimeter) emitted by asteroids and comets as they make their closest approach to the Sun. This dust doesnt penetrateEarths layers of atmosphere, but the innermost planet of our solar system, Mercury, doesnt have this convenient cushioning.Just as Mercury is affected by the impacts of large meteoroids, its also shaped by the many smaller-scale impacts it experiences. These tiny collisions are thought to vaporize atoms and molecules from the planets surface, which quickly dissociate. This process adds metals to Mercurys exosphere, the planets extremely tenuous atmosphere.Modeling PopulationsDistribution of the directions from which meteoroids originate before impacting Mercurys surface, as averaged over its entire orbit. Local time of 12 hr corresponds to the Sun-facing side. A significant asymmetry is seen between the dawn (6 hrs) and dusk (18 hrs) rates. [Pokorn et al. 2017]The metal distribution in the exosphere provides a way for us to measure the effect of micrometeoroid impacts on Mercury but this only works if we have accurate models of the process. A team of scientists led by Petr Pokorn (The Catholic University of America and NASA Goddard SFC) has now worked to improve our picture of micrometeoroid impact vaporization on Mercury.Pokorn and collaborators argue that two meteoroid populations Jupiter-family comets (short-period) and Halley-type comets (long-period) contribute the dust for the majority of micrometeoroid impacts on Mercury. The authors model the dynamics and evolution of these two populations, reproducing the

  3. Evolution of Mercury's Obliquity

    NASA Astrophysics Data System (ADS)

    Yseboodt, M.; Margot, J. L.

    2005-05-01

    Mercury has a near-zero obliquity, i.e. its spin axis is nearly perpendicular to its orbital plane. In order to constrain the size of the planet's core with the framework suggested by Peale (1976), the obliquity must be known precisely. Rambaux and Bois (2004) have suggested that Mercury's obliquity varies on thousand-year timescales due to planetary perturbations, potentially ruining the feasibility of Peale's experiment. We use a Hamiltonian approach (free of energy dissipation) to study the spin-orbit evolution of Mercury subject to planetary perturbations. We can reproduce an obliquity evolution similar to that of Rambaux and Bois (2004) if we introduce the planetary perturbations abruptly, i.e. by a step function. But if we introduce the planetary effects smoothly starting from an equilibrium position corresponding to the Cassini state (where the spin axis, the normal to the invariable plane and the normal to the orbital plane are aligned), the thousand-year oscillations in the obliquity do not appear. We find an equilibrium value for the obliquity of ˜1.6 arcmin for (B-A)/C = 1.2 10-4 and (C-A)/C = 2.4 10-4, which are combinations of the moments of inertia corresponding to the Mariner 10 gravity data. Our results indicate that planetary perturbations do not force short-period oscillations in Mercury's obliquity, even though such oscillations may appear in numerical integrations involving artificial departures from the Cassini state or the sudden onset of perturbations. Peale (2004) has shown that the periods of damping of the free motions (free precession or free libration) are short compared to the age of the solar system, such that oscillations in obliquity are expected to decay. In the absence of excitation processes, Mercury's obliquity will remain constant, suggesting that one of the important conditions for the success of Peale's experiment is realized.

  4. MESSENGER'S First and Second Flybys of Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2009-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only approximately 1000 km above the surface. An overview of the MESSENGER mission and its January 14th and October 6th, 2008 close flybys of Mercury will be provided. Primary science objectives and the science instrumentation will be described. Initial results from MESSENGER will be discussed with an emphasis on the magnetic field and charged particle measurements.

  5. The Plasma Environment at Mercury

    NASA Technical Reports Server (NTRS)

    Raines, James M.; Gershman, Daniel J.; Zurbuchen, Thomas H.; Gloeckler, George; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Krimigis, Stamatios M.; Killen, Rosemary M.; Sarantos, Menalos; hide

    2011-01-01

    Mercury is the least explored terrestrial planet, and the one subjected to the highest flux of solar radiation in the heliosphere. Its highly dynamic, miniature magnetosphere contains ions from the exosphere and solar wind, and at times may allow solar wind ions to directly impact the planet's surface. Together these features create a plasma environment that shares many features with, but is nonetheless very different from, that of Earth. The first in situ measurements of plasma ions in the Mercury space environment were made only recently, by the Fast Imaging Plasma Spectrometer (FIPS) during the MESSENGER spacecraft's three flybys of the planet in 2008-2009 as the probe was en route to insertion into orbit about Mercury earlier this year. Here. we present analysis of flyby and early orbital mission data with novel techniques that address the particular challenges inherent in these measurements. First. spacecraft structures and sensor orientation limit the FIPS field of view and allow only partial sampling of velocity distribution functions. We use a software model of FIPS sampling in velocity space to explore these effects and recover bulk parameters under certain assumptions. Second, the low densities found in the Mercury magnetosphere result in a relatively low signal-to-noise ratio for many ions. To address this issue, we apply a kernel density spread function to guide removal of background counts according to a background-signature probability map. We then assign individual counts to particular ion species with a time-of-flight forward model, taking into account energy losses in the carbon foil and other physical behavior of ions within the instrument. Using these methods, we have derived bulk plasma properties and heavy ion composition and evaluated them in the context of the Mercury magnetosphere.

  6. Mercury Project

    NASA Image and Video Library

    1959-01-01

    In this 1959 photograph, technicians prepare tail sections for Mercury-Redstone vehicles in Building 4706 at Redstone Arsenal in Huntsville, Alabama. Developed by Dr. Wernher von Braun and the rocket team at Redstone, the Mercury-Redstone launched the first two marned U.S. missions.

  7. Mercury Project

    NASA Image and Video Library

    1963-05-16

    The recovery operation of the Faith 7 spacecraft after the completion of the 1-1/2 day orbital flight (MA-9 mission) with Astronaut Gordon Cooper. Navy frogmen attach the flotation collar to the spacecraft. The MA-9 mission was the last flight of the Mercury Project and launched on May 15, 1963 boosted by The Mercury-Atlas launch vehicle.

  8. Mercury Project

    NASA Image and Video Library

    1963-09-09

    Astronaut Alan B. Shepard, one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The Freedom 7 spacecraft boosted by Mercury-Redstone vehicle for the MR-3 mission made the first marned suborbital flight and Astronaut Shepard became the first American in space.

  9. Mercury Project

    NASA Image and Video Library

    1959-04-27

    Astronaut Walter M. "Wally" Schirra, one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The MA-8 (Mercury-Atlas) mission with Sigma 7 spacecraft was the third marned orbital flight by the United States, and made the six orbits in 9-1/4 hours.

  10. Mercury Project

    NASA Image and Video Library

    1959-04-27

    Astronaut Virgil I. "Gus" Grissom, one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The MR-4 mission, boosted by the Mercury-Redstone vehicle, made the second marned suborbital flight. The capsule, Liberty Bell 7, sank into the sea after the splashdown.

  11. Mercury Project

    NASA Image and Video Library

    1959-04-27

    Astronaut John H. Glenn, one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The MA-6 mission, boosted by the Mercury-Atlas vehicle, was the first manned orbital launch by the United States, and carried Astronaut Glenn aboard the Friendship 7 spacecraft to orbit the Earth.

  12. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Remote sensing and physical data and the Moon. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Imagery data from Mariner 10 and Lunar Orbiter IV form the major base of observations analyzed. But a variety of other information aids in constraining the composition and structure of the Moon and Mercury, and in particular, provides input to the problem of the nature and origin of their intercrater plains. This information for Mercury is remotely sensed from Earth or from the Mariner 10 spacecraft. Lunar data includes, of course, ground truth information from the Apollo landing sites. Since neither intercrater region was sampled, lunar and Mercurian data are similar in type and limitations. Constraints on surface and interior composition and structure are reviewed.

  13. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Remote sensing and physical data and the Moon. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    Imagery data from Mariner 10 and Lunar Orbiter IV form the major base of observations analyzed. But a variety of other information aids in constraining the composition and structure of the Moon and Mercury, and in particular, provides input to the problem of the nature and origin of their intercrater plains. This information for Mercury is remotely sensed from Earth or from the Mariner 10 spacecraft. Lunar data includes, of course, ground truth information from the Apollo landing sites. Since neither intercrater region was sampled, lunar and Mercurian data are similar in type and limitations. Constraints on surface and interior composition and structure are reviewed.

  14. Physical study of planets and satellites

    NASA Technical Reports Server (NTRS)

    Pettengill, G. H.

    1973-01-01

    Review of recent progress made in various aspects of planetary research, followed by some comments on ongoing unpublished research at various centers. The results of planetary atmosphere research are cited for Mercury, Venus, Mars, the Jupiter system, Saturn and Titan (the largest satellite of Saturn), and Uranus and Neptune. Findings regarding planetary surfaces are presented for Mercury, Venus, and Mars. Current unpublished research concerning Venus, the minor planets, Jupiter, and Saturn is reviewed, and work currently being performed at the IAU Planetary Photographic Data Center at Meudon, by the Planetary Research Center at the Lowell Observatory, and within the framework of the International Planetary Patrol Program is evaluated.

  15. Mercury's Magma Ocean

    NASA Astrophysics Data System (ADS)

    Parman, S. W.; Parmentier, E. M.; Wang, S.

    2016-12-01

    The crystallization of Mercury's magma ocean (MMO) would follow a significantly different path than the terrestrial or lunar magma ocean. Evidence from the MESSENGER mission [1] indicates that Mercury's interior has an oxygen fugacity (fO2) orders of magnitude lower any other terrestrial planet (3-8 log units below the iron-wustite buffer = IW-3 to IW-8; [2]). At these conditions, silicate melts and minerals have negligible Fe contents. All Fe is present in sulfides or metal. Thus, the build up of Fe in the last dregs of the lunar magma ocean, that is so important to its evolution, would not happen in the MMO. There would be no overturn or plagioclase flotation crust. Sulfur solubility in silicate melts increases dramatically at low fO2, from 1 wt% at IW-3 to 8wt% at IW-8 [3]. Thus it is possible, perhaps probable, that km-thick layers of sulfide formed during MMO crystallization. Some of the sulfides (e.g. CaS) have high partition coefficients for trace elements and so could control the spatial distribution of radioactive heat producing elements such as U, Th and K. This in turn would have first order effects on the thermal and chemical evolution of the planet. The distribution of the sulfide layers depend upon the density of the sulfides that form in the MMO. At such low fO2, S forms compounds with a range of elements not typical for other planets: Ca, Mg, Na, K. The densities of these sulfides vary widely, with Mg and Ca-rich sulfides being more dense than estimated MMO densities, and Na and K-rich sulfides being less dense than the MMO. Thus sulfide sinking and floating may produce substantial chemical layering on Mercury, potentially including an Mg-Ca rich deep layer and a Na-K rich shallow layer or possibly floatation crust. The total amount of S in the MMO depends on the fO2 and the bulk S content of Mercury, both of which are poorly constrained. In the most extreme case, if the MMO had an fO2of IW-8 and was sulfide saturated from the start, a total

  16. Return to Mercury: a global perspective on MESSENGER's first Mercury flyby.

    PubMed

    Solomon, Sean C; McNutt, Ralph L; Watters, Thomas R; Lawrence, David J; Feldman, William C; Head, James W; Krimigis, Stamatios M; Murchie, Scott L; Phillips, Roger J; Slavin, James A; Zuber, Maria T

    2008-07-04

    In January 2008, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft became the first probe to fly past the planet Mercury in 33 years. The encounter revealed that Mercury is a dynamic system; its liquid iron-rich outer core is coupled through a dominantly dipolar magnetic field to the surface, exosphere, and magnetosphere, all of which interact with the solar wind. MESSENGER images confirm that lobate scarps are the dominant tectonic landform and record global contraction associated with cooling of the planet. The history of contraction can be related to the history of volcanism and cratering, and the total contractional strain is at least one-third greater than inferred from Mariner 10 images. On the basis of measurements of thermal neutrons made during the flyby, the average abundance of iron in Mercury's surface material is less than 6% by weight.

  17. Mercury's Densely Cratered Surface

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Mariner 10 took this picture (FDS 27465) of the densely cratered surface of Mercury when the spacecraft was 18,200 kilometers (8085 miles) from the planet on March 29. The dark line across top of picture is a 'dropout' of a few TV lines of data. At lower left, a portion of a 61 kilometer (38 mile) crater shows a flow front extending across the crater floor and filling more than half of the crater. The smaller, fresh crater at center is about 25 kilometers (15 miles) in diameter. Craters as small as one kilometer (about one-half mile) across are visible in the picture.

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    Image Credit: NASA/JPL/Northwestern University

  18. Uncratered Area on Mercury

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A dark, smooth, relatively uncratered area on Mercury was photographed (FDS 226) two hours after Mariner 10 flew by the planet on March 29 from a range of 86,000 kilometers (54,000 miles). Above and to the left of center is a surface similar to the mane material of Earth's moon. It embays and covers rougher, older, heavily cratered topography like that, which can be seen in both upper corners of this picture. The history of heavy cratering seems to be followed by volcanic filling, similar to the process on the Moon. The prominent, sharp crater with a central peak (center) is 30 kilometers (19 miles) across. It is located on the upper left edge of a very bright surface area. The bright crater, to its right is 10 kilometers (6 miles) in diameter. The sun is from the right.

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    Image Credit: NASA/JPL/Northwestern University

  19. Mercury's Magnetic Field

    NASA Astrophysics Data System (ADS)

    Johnson, C. L.

    2014-12-01

    Mercury is the only inner solar system body other than Earth to possess an active core dynamo-driven magnetic field and the only planet with a small, highly dynamic magnetosphere. Measurements made by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft have provided a wealth of data on Mercury's magnetic field environment. Mercury's weak magnetic field was discovered 40 years ago by the Mariner 10 spacecraft, but its large-scale geometry, strength and origin could not be definitively established. MESSENGER data have shown that the field is dynamo-generated and can be described as an offset axisymmetric dipole field (hereafter OAD): the magnetic equator lies ~0.2 RM (RM = 2440 km) north of the geographic equator and the dipole moment is 2.8 x1019 Am2 (~0.03% that of Earth's). The weak internal field and the high, but variable, solar wind ram pressure drive vigorous magnetospheric dynamics and result in an average distance from the planet center to the sub-solar magnetopause of only 1.42 RM. Magnetospheric models developed with MESSENGER data have allowed re-analysis of the Mariner 10 observations, establishing that there has been no measureable secular variation in the internal field over 40 years. Together with spatial power spectra for the OAD, this provides critical constraints for viable dynamo models. Time-varying magnetopause fields induce secondary core fields, the magnitudes of which confirm the core radius estimated from MESSENGER gravity and Earth-based radar data. After accounting for large-scale magnetospheric fields, residual signatures are dominated by additional external fields that are organized in the local time frame and that vary with magnetospheric activity. Birkeland currents have been identified, which likely close in the planetary interior at depths below the base of the crust. Near-periapsis magnetic field measurements at altitudes greater than 200 km have tantalizing hints of crustal fields, but crustal

  20. Collisional Evolution of Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Agnor, C.; Asphaug, E.

    2004-12-01

    The terrestrial planets are generally thought to have formed via the collisional accumulation of rocky bodies. The characteristics of the planets produced by this process are, to a large degree, determined by their collisional evolution, and their associated differentiation and thermal evolution. Studies of planet formation and planetary collisional evolution have typically been conducted separately. Most works of late-stage planet formation use perfectly inelastic mergers to model collisions (e.g. Agnor, Canup & Levison 1999, Chambers 2001, Levison & Agnor 2003), with certain recognized inadequacies, notably prohibitively large spin angular momentum acquired as a planet grows. To date, studies of the collisional evolution of terrestrial planets has focused on determining the efficacy of single impacts to account for particular planetary characteristics and the formation of satellites (e.g. Benz et al. 1988, Canup & Asphaug 2001, Canup 2004). It has been recognized for some time (Wetherill 1985) that the final characteristics (e.g. spin state, bulk composition, isotopic age) of an accreting planet are determined not by the last or single largest collision but by all of the major collisional encounters in a planet's history (Agnor, Canup & Levison 1999). As demonstrated by our impact models, each major impact changes the silicate to metal ratio, the thermal state, and the spin state, and sets the stage for the subsequent collision. We are studying collisional dynamics and outcomes common to the late stage of terrestrial planet formation. We use smooth particle hydrodynamics model collisions in an effort to identify the range of impact dynamics that allow for accretion (i.e. mass growth instead of mass loss). In our initial study we found that for dynamical environments typical of most late stage accretion models, about half of all collisions between equal mass planetary embryos do not result in accumulation into a larger embryo (Agnor & Asphaug 2004). We will

  1. Extrasolar Planets and Prospects for Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Marcy, Geoffrey W.; Butler, R. Paul; Vogt, Steven S.; Fischer, Debra A.

    2004-06-01

    Examination of ˜2000 sun--like stars has revealed 97 planets (as of 2002 Nov), all residing within our Milky Way Galaxy and within ˜200 light years of our Solar System. They have masses between 0.1 and 10 times that of Jupiter, and orbital sizes of 0.05--5 AU. Thus planets occupy the entire detectable domain of mass and orbits. News &summaries about extrasolar planets are provided at: http://exoplanets.org. These planets were all discovered by the wobble of the host stars, induced gravitationally by the planets, causing a periodicity in the measured Doppler effect of the starlight. Earth--mass planets remain undetectable, but space--based missions such as Kepler, COROT and SIM may provide detections of terrestrial planets within the next decade. The number of planets increases with decreasing planet mass, indicating that nature makes more small planets than jupiter--mass planets. Extrapolation, though speculative, bodes well for an even larger number of earth--mass planets. These observations and the theory of planet formation suggests that single sun--like stars commonly harbor earth--sized rocky planets, as yet undetectable. The number of planets increases with increasing orbital distance from the host star, and most known planets reside in non--circular orbits. Many known planets reside in the habitable zone (albeit being gas giants) and most newly discovered planets orbit beyond 1 AU from their star. A population of Jupiter--like planets may reside at 5--10 AU from stars, not easily detectable at present. The sun--like star 55 Cancri harbors a planet of 4--10 Jupiter masses orbiting at 5.5 AU in a low eccentricity orbit, the first analog of our Jupiter, albeit with two large planets orbiting inward. To date, 10 multiple--planet systems have been discovered, with four revealing gravitational interactions between the planets in the form of resonances. GJ 876 has two planets with periods of 1 and 2 months. Other planetary systems are ``hierarchical'', consisting

  2. The Limiting Sizes of the Habitable Planets

    NASA Technical Reports Server (NTRS)

    Huang, Su-Shu

    1960-01-01

    The astrobiological problem of the occurrence of life in the universe is discussed from the standpoint of the size and nature of planets upon which living organisms might arise. The conclusion is tentatively drawn that the most likely radius of a habitable planet lies between 10(exp 8) cm and 2 x 10(exp 9) cm. Conditions of temperature and density also bear upon the occurrence of life; thus the moon and Mercury, although both fall within the range of favorable radii, are nevertheless believed uninhabited by indigeneous life.

  3. Mercury's Exosphere During MESSENGER's Second Flyby: Detection of Magnesium and Distinct Distributions of Neutral Species

    NASA Technical Reports Server (NTRS)

    McClintock, William E.; Vervack, Ronald J., Jr.; Bradley, E. Todd; Killen, Rosemary M.; Mouawad, Nelly; Sprague, Ann L.; Burger, Matthew H.; Solomon, Sean C.; Izenberg, Noam R.

    2009-01-01

    During MESSENGER's second Mercury flyby, the Mercury Atmospheric and Surface Composition Spectrometer observed emission from Mercury's neutral exosphere. These observations include the first detection of emission from magnesium. Differing spatial distributions for sodium, calcium, and magnesium were revealed by observations beginning in Mercury's tail region, approximately 8 Mercury radii anti-sunward of the planet, continuing past the nightside, and ending near the dawn terminator. Analysis of these observations, supplemented by observations during the first Mercury flyby as well as those by other MESSENGER instruments, suggests that the distinct spatial distributions arise from a combination of differences in source, transfer, and loss processes.

  4. The study Earth-like planets using spacecraft

    NASA Astrophysics Data System (ADS)

    Vidmachenko, A. P.; Morozhenko, O. V.

    2014-10-01

    The Solar system consists of the Sun, large (classical), dwarf, small planets and their satellites, comets, meteoroids, small meteoritic particles and dust grains. The eight classical planets are divided into terrestrial planets (Mercury, Venus, Earth, Mars) and giant planets (Jupiter, Saturn, Uranus, Neptune). The main components of the Earth-like planets atmospheres are nitrogen and carbon dioxide. The formation of the terrestrial planets' traced in some detail, calculated the distance between the planets, their mass, orbital period around the Sun, the inclination of the axis satisfactorily agree with observational data. Terrestrial planets have much in common: small size and weight, the average density is several times greater than the density of water, slow rotation around its axis, few satellites or lack thereof, hard surface and so on. There are volcanoes on Venus, Earth and Mars, and in the surface layers of all four planets more or less traces of tectonic activity (mountain building processes) and intense meteorite bombardment as one of the main factors of the Mars and Mercury surface formation. On Earth meteor crater almost completely obliterated by tectonic and erosional processes while they survived much better on Venus.

  5. The partial volatilization of Mercury

    NASA Technical Reports Server (NTRS)

    Cameron, A. G. W.

    1985-01-01

    During recent years research on the primitive solar nebula has followed two main themes: (1) Very early in the development of the nebula conditions probably favored the occurrence of major gaseous instabilities leading to the formation of giant gaseous protoplanets, but the rapid rise of the external temperature soon evaporated the envelopes of these protoplanets, possibly leaving behind precipitated solids which formed the cores and mantles of the terrestrial planets. (2) Models of the nebula indicate a later stage when conditions in the inner Solar System became very hot; at the position of Mercury the temperature was probably in the range 2500-3500 K. This leads to the hypothesis that the original protomercury was a body substantially more massive than the present planet and of normal composition, but that when it was immersed in the high-temperature field of the dissipating solar nebula, most of the rocky mantle was vaporized and mixed into the solar nebula gases and carried away by them. This hypothesis is investigated in the present paper. For simplicity the vaporization of a mantle composed of enstatite, MgSiO3, was computed for a planet with 2.25 the mass of Mercury at a temperature of 3000 K. It is argued that the mantle could probably be largely removed in the available time of 30,000 yrs. Subsequent accretion would restore some magnesium silicates to the mantle of the planet.

  6. Planet Ocean

    NASA Astrophysics Data System (ADS)

    Afonso, Isabel

    2014-05-01

    A more adequate name for Planet Earth could be Planet Ocean, seeing that ocean water covers more than seventy percent of the planet's surface and plays a fundamental role in the survival of almost all living species. Actually, oceans are aqueous solutions of extraordinary importance due to its direct implications in the current living conditions of our planet and its potential role on the continuity of life as well, as long as we know how to respect the limits of its immense but finite capacities. We may therefore state that natural aqueous solutions are excellent contexts for the approach and further understanding of many important chemical concepts, whether they be of chemical equilibrium, acid-base reactions, solubility and oxidation-reduction reactions. The topic of the 2014 edition of GIFT ('Our Changing Planet') will explore some of the recent complex changes of our environment, subjects that have been lately included in Chemistry teaching programs. This is particularly relevant on high school programs, with themes such as 'Earth Atmosphere: radiation, matter and structure', 'From Atmosphere to the Ocean: solutions on Earth and to Earth', 'Spring Waters and Public Water Supply: Water acidity and alkalinity'. These are the subjects that I want to develop on my school project with my pupils. Geographically, our school is located near the sea in a region where a stream flows into the sea. Besides that, our school water comes from a borehole which shows that the quality of the water we use is of significant importance. This project will establish and implement several procedures that, supported by physical and chemical analysis, will monitor the quality of water - not only the water used in our school, but also the surrounding waters (stream and beach water). The samples will be collected in the borehole of the school, in the stream near the school and in the beach of Carcavelos. Several physical-chemical characteristics related to the quality of the water will

  7. Mercury Project

    NASA Image and Video Library

    1961-01-31

    A three-year-old chimpanzee, named Ham, in the biopack couch for the MR-2 suborbital test flight. On January 31, 1961, a Mercury-Redstone launch from Cape Canaveral carried the chimpanzee "Ham" over 640 kilometers down range in an arching trajectory that reached a peak of 254 kilometers above the Earth. The mission was successful and Ham performed his lever-pulling task well in response to the flashing light. NASA used chimpanzees and other primates to test the Mercury Capsule before launching the first American astronaut Alan Shepard in May 1961. The successful flight and recovery confirmed the soundness of the Mercury-Redstone systems.

  8. Mercury Project

    NASA Image and Video Library

    1961-01-01

    A three-year-old chimpanzee, named Ham, in the biopack couch for the MR-2 suborbital test flight. On January 31, 1961, a Mercury-Redstone launch from Cape Canaveral carried the chimpanzee "Ham" over 640 kilometers down range in an arching trajectory that reached a peak of 254 kilometers above the Earth. The mission was successful and Ham performed his lever-pulling task well in response to the flashing light. NASA used chimpanzees and other primates to test the Mercury Capsule before launching the first American astronaut Alan Shepard in May 1961. The successful flight and recovery confirmed the soundness of the Mercury-Redstone systems.

  9. Mercury. [Mariner 10 observations and planetary properties

    NASA Technical Reports Server (NTRS)

    Gault, D. E.; Cassen, P.; Burns, J. A.; Strom, R. G.

    1977-01-01

    Information about Mercury obtained with the Mariner 10 spacecraft is summarized together with results of theoretical studies and ground-based observations. It is shown that Mercury is very likely a differentiated body, probably contains a large earthlike iron-rich core, and displays a surface similar to the moon's, which suggests a similar evolutionary history. The size and mass of Mercury are discussed along with its orbit, rotation, atmosphere, magnetic field, and magnetosphere. Surface features of Mercury are described on the basis of Mariner 10 pictures, with detailed attention given to the major physiographic provinces, the structure of the Caloris basin, the tectonic framework of the planet, crater morphology, the planet's optical and thermal properties, and cartography. The composition and structure of the interior are examined, and the thermal history of Mercury is considered. The planet's geologic history is divided into five stages or epochs: (1) accretion and differentiation, (2) terminal heavy bombardment, (3) Caloris basin formation, (4) basin flooding, and (5) postfilling lighter bombardment.

  10. Isotropic Contraction Of Mercury Due To Despinning

    NASA Astrophysics Data System (ADS)

    Matsuyama, Isamu; Bills, B. G.

    2009-09-01

    Mercury's slow rotation period of 59 days is presumably the result of solar tides driving its initial rotational state to the present 3:2 spin-orbit resonance. The observed large gravity coefficients can be explained as due to a remnant rotational bulge recording an initial rotation period of a few days (Matsuyama and Nimmo 2009). Despinning changes the shape of the rotational bulge, generating both compressional and extensional stresses (Melosh 1977). However, Mercury's surface is dominated by compressional tectonic features (Watters et al. 1998), and the inferred global contraction has been explained as due to thermal cooling (Solomon 1976). In addition to non-isotropic changes associated with the rotational flattening, despinning causes isotropic contraction of the entire planet. We consider the effect of the compressional stresses generated by this isotropic contraction on the predicted tectonic pattern. References Matsuyama and Nimmo. Gravity and tectonic patterns of Mercury: Effect of tidal deformation, spin-orbit resonance, nonzero eccentricity, despinning, and reorientation. J. Geophys. Res. (2009) vol. 114 pp. E01010 Melosh. Global tectonics of a despun planet. Icarus (1977) vol. 31 pp. 221-243 Solomon. Some aspects of core formation in Mercury. Icarus (1976) vol. 28 pp. 509-521 Watters et al. Topography of lobate scarps on Mercury: New constraints on the planet's contraction. Geology (1998) vol. 26 pp. 991-994

  11. A comprehensive study of Mercury and MESSENGER orbit determination

    NASA Astrophysics Data System (ADS)

    Genova, Antonio; Mazarico, Erwan; Goossens, Sander; Lemoine, Frank G.; Neumann, Gregory A.; Nicholas, Joseph B.; Rowlands, David D.; Smith, David E.; Zuber, Maria; Solomon, Sean C.

    2016-10-01

    The MErcury, Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbited the planet Mercury for more than 4 years. The probe started its science mission in orbit around Mercury on 18 March 2011. The Mercury Laser Altimeter (MLA) and radio science system were the instruments dedicated to geodetic observations of the topography, gravity field, orientation, and tides of Mercury. X-band radio-tracking range-rate data collected by the NASA Deep Space Network (DSN) allowed the determination of Mercury's gravity field to spherical harmonic degree and order 100, the planet's obliquity, and the Love number k2.The extensive range data acquired in orbit around Mercury during the science mission (from April 2011 to April 2015), and during the three flybys of the planet in 2008 and 2009, provide a powerful dataset for the investigation of Mercury's ephemeris. The proximity of Mercury's orbit to the Sun leads to a significant perihelion precession attributable to the gravitational flattening of the Sun (J2) and the Parameterized Post-Newtonian (PPN) coefficients γ and β, which describe the space curvature produced by a unit rest mass and the nonlinearity in superposition of gravity, respectively. Therefore, the estimation of Mercury's ephemeris can provide crucial information on the interior structure of the Sun and Einstein's general theory of relativity. However, the high correlation among J2, γ, and β complicates the combined recovery of these parameters, so additional assumptions are required, such as the Nordtvedt relationship η = 4β - γ - 3.We have modified our orbit determination software, GEODYN II, to enable the simultaneous integration of the spacecraft and central body trajectories. The combined estimation of the MESSENGER and Mercury orbits allowed us to determine a more accurate gravity field, orientation, and tides of Mercury, and the values of GM and J2 for the Sun, where G is the gravitational constant and M is the solar mass

  12. Mariner Venus Mercury, 1973. [close flyby investigation of mercury after Venus-flyby, and observation of Kohoutek comet

    NASA Technical Reports Server (NTRS)

    Wilson, J. H.

    1973-01-01

    The Mariner Venus Mercury 1973 unmanned mission is discussed, which is designed to conduct a close flyby investigation of the planet Mercury after using the gravity-turn technique in a Venus flyby. Its scientific purposes include photographic, thermal, and spectral surveys, radio occulation, and charged particle/magnetic measurements at each planet, observation of solar-system fields and particles from 1.0 a.u. down to 0.4 a.u., and comparative planetary surveys between the Earth, the Moon, Venus, and Mercury. It is also intended to observe Kohoutek's comet. The trajectory permits establishment of a solar orbit in phase with Mercury's, permitting repeated encounters with that planet.

  13. Mercury: infrared evidence for nonsynchronous rotation.

    PubMed

    Soter, S L

    1966-09-02

    An infrared observation of the dark side of Mercury made by Pettit and Nicholson in 1923 led them to suggest that the planet rotates nonsynchronously. Their early measurements, if taken at face value, would imply a brightness temperature of about 180 degrees K for the dark side. The asymmetry of the infrared phase curve is further interpreted as suggesting direct rotation.

  14. The Cambridge photographic atlas of the planets

    NASA Technical Reports Server (NTRS)

    Briggs, G.; Taylor, F.

    1982-01-01

    The origin of the solar systems is considered along with the formation of the planets, the evolution of the planets, the surfaces of solid planets, and the atmosphere of the planets. A description is provided of the various planets of the solar system. It is pointed out that Mercury was little known until March 1974 when the Mariner 10 spacecraft made the first of its three flybys of that body. In the case of Venus, the Pioneer mission to Venus by NASA in 1978 provided a breakthrough concerning a knowledge of the solid body hidden beneath the clouds. The characteristics of the planet earth are discussed together with information about the moon. A shaded relief map of Mars illustrates the geographic features of this planet. The map was produced with the aid of Mariner 9 photographs. Maps of the Jovian system based on photographs provided by space missions are also presented, and the Saturnian system is discussed, taking into account major satellites and rings of Saturn.

  15. Mercury orbiter - an interdisciplinary mission

    NASA Astrophysics Data System (ADS)

    Grard, R.; Scoon, G.; Coradini, M.

    Mercury is the innermost and a less known terrestrial planet of the Solar System. It possesses a very high density (5.3 g/cu cm at 10 kbar), a small but unexpected magnetic moment (6 x 10-3 that of Earth), and a tenuous exosphere; ground-based radar observations indicate that water ice may exist at the poles. There are still fundamental questions about its accretion and catering history, and its thermal and chemical evolution. The size of Mercury's magnetosphere is just 5% of that of Earth; substorms last 5 min, on average, and their generation process is influenced by the absence of an ionosphere. The model payload of Mercury Orbiter includes a multi-spectral imager, a gamma-and X -ray detector, a magnetometer, charged-particle analysers, a wave receiver and an ion emitter for spacecraft potential control. The spacecraft, the design of which is inherited from ESA's Cluster spacecraft, has a dry mass of 626 kg and is stabilized at 10 rmp, but the telemetry antenna is despun. The bit rate varies between 1.4 and 9 kb/s over the range 1.6-0.64 AU. The spacecraft, launched from Kourou with an Ariane-5, reaches its destination after two gravity assists at Venus and two at Mercury. Its orbit is polar with periherm and apherm altitudes of 400 and 16 800 km, respectively. The spacecraft's operating lifetime around Mercury is 3 Hermean years.

  16. Geodesy at Mercury with MESSENGER

    NASA Technical Reports Server (NTRS)

    Smith, David E.; Zuber, Maria t.; Peale, Stanley J.; Phillips, Roger J.; Solomon, Sean C.

    2006-01-01

    In 2011 the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft will enter Mercury orbit and begin the mapping phase of the mission. As part of its science objectives the MESSENGER mission will determine the shape and gravity field of Mercury. These observations will enable the topography and the crustal thickness to be derived for the planet and will determine the small libration of the planet about its axis, the latter critical to constraining the state of the core. These measurements require very precise positioning of the MESSENGER spacecraft in its eccentric orbit, which has a periapsis altitude as low as 200 km, an apoapsis altitude near 15,000 km, and a closest approach to the surface varying from latitude 60 to about 70 N. The X-band tracking of MESSENGER and the laser altimetry are the primary data that will be used to measure the planetary shape and gravity field. The laser altimeter, which has an expected range of 1000 to 1200 km, is expected to provide significant data only over the northern hemisphere because of MESSENGER's eccentric orbit. For the southern hemisphere, radio occultation measurements obtained as the spacecraft passes behind the planet as seen from Earth and images obtained with the imaging system will be used to provide the long-wavelength shape of the planet. Gravity, derived from the tracking data, will also have greater resolution in the northern hemisphere, but full global models for both topography and gravity will be obtained at low harmonic order and degree. The limiting factor for both gravity and topography is expected to be knowledge of the spacecraft location. Present estimations are that in a combined tracking, altimetry, and occultation solution the spacecraft position uncertainty is likely to be of order 10 m. This accuracy should be adequate for establishing an initial geodetic coordinate system for Mercury that will enable positioning of imaged features on the surface, determination of

  17. Our present view of Mercury and Venus

    NASA Technical Reports Server (NTRS)

    Danielson, G. E., Jr.

    1975-01-01

    The discipline of planetology received a quantum jump in new information on the planets Mercury and Venus from the Mariner 10 spacecraft. A detailed look at the ultraviolet markings in the upper atmosphere of Venus and their attendant motion has stimulated a considerable reevaluation of theories concerning the circulation, composition, and nature of this planet's upper atmosphere. The geologic history of Mercury as revealed by Mariner 10's television science data, from two close flybys, has challenged the prevalent theories of planetary evolution. The Mercury surface morphology and optical properties resemble those of the moon and seem to record a similar sequence of events despite their differences in density and proximity to both the sun and the asteroid belt.

  18. The magnetic field of Mercury, part 1

    NASA Technical Reports Server (NTRS)

    Ness, N. F.; Behannon, K. W.; Lepping, R. P.; Whang, Y. C.

    1974-01-01

    An updated analysis and interpretation is presented of the magnetic field observations obtained during the Mariner 10 encounter with the planet Mercury. The combination of data relating to position of the detached bow shock wave and magnetopause, and the geometry and magnitude of the magnetic field within the magnetosphere-like region surrounding Mercury, lead to the conclusion that an internal planetary field exists with dipole moment approximately 5.1 x 10 the 22nd power Gauss sq cm. The dipole axis has a polarity sense similar to earth's and is tilted 7 deg from the normal to Mercury's orbital plane. The magnetic field observations reveal a significant distortion of the modest Hermean field (350 Gamma at the equator) by the solar wind flow and the formation of a magnetic tail and neutral sheet which begins close to the planet on the night side. The composite data is not consistent with a complex induction process driven by the solar wind flow.

  19. Mercury radar imaging: evidence for polar ice.

    PubMed

    Slade, M A; Butler, B J; Muhleman, D O

    1992-10-23

    The first unambiguous full-disk radar mapping of Mercury at 3.5-centimeter wavelength, with the Goldstone 70-meter antenna transmitting and 26 antennas of the Very Large Array receiving, has provided evidence for the presence of polar ice. The radar experiments, conducted on 8 and 23 August 1991, were designed to image the half of Mercury not photographed by Mariner 10. The orbital geometry allowed viewing beyond the north pole of Mercury; a highly reflective region was clearly visible on the north pole during both experiments. This polar region has areas in which the circular polarization ratio (pt) was 1.0 to 1.4; values < approximately 0.1 are typical for terrestrial planets. Such high values of have hitherto been observed in radar observations only from icy regions of Mars and icy outer planet satellites.

  20. Messenger Observations of Mercury's Bow Shock and Magnetopause

    NASA Technical Reports Server (NTRS)

    Slavin J. A.; Acuna, M. H.; Anderson, B. J.; Benna, M.; Gloeckler, G.; Krimigis, S. M.; Raines, M.; Schriver, D.; Travnicek, P.; Zurbuchen, T. H.

    2008-01-01

    The MESSENGER spacecraft made the first of three flybys of Mercury on January 14.2008 (1). New observations of solar wind interaction with Mercury were made with MESSENGER'S Magnetometer (MAG) (2.3) and Energetic Particle and Plasma Spectrometer (EPPS) - composed of the Energetic Particle Spectrometer (EPS) and Fast Imaging Plasma Spectrometer (FIPS) (3,4). These MESSENGER observations show that Mercury's magnetosphere has a large-scale structure that is distinctly Earth-like, but it is immersed in a comet-like cloud of planetary ions [5]. Fig. 1 provides a schematic view of the coupled solar wind - magnetosphere - neutral atmosphere - solid planet system at Mercury.

  1. Laser altimeter observations from MESSENGER's first Mercury flyby.

    PubMed

    Zuber, Maria T; Smith, David E; Solomon, Sean C; Phillips, Roger J; Peale, Stanton J; Head, James W; Hauck, Steven A; McNutt, Ralph L; Oberst, Jürgen; Neumann, Gregory A; Lemoine, Frank G; Sun, Xiaoli; Barnouin-Jha, Olivier; Harmon, John K

    2008-07-04

    A 3200-kilometers-long profile of Mercury by the Mercury Laser Altimeter on the MESSENGER spacecraft spans approximately 20% of the near-equatorial region of the planet. Topography along the profile is characterized by a 5.2-kilometer dynamic range and 930-meter root-mean-square roughness. At long wavelengths, topography slopes eastward by 0.02 degrees , implying a variation of equatorial shape that is at least partially compensated. Sampled craters on Mercury are shallower than their counterparts on the Moon, at least in part the result of Mercury's higher gravity. Crater floors vary in roughness and slope, implying complex modification over a range of length scales.

  2. Lateral Viscosity Variations and the Contractional History of Mercury

    NASA Astrophysics Data System (ADS)

    Mohit, P. S.; Phillips, R. J.; Johnson, C. L.; Hauck, S. A.; Zuber, M. T.; Neumann, G. A.; Solomon, S. C.

    2008-12-01

    The lobate scarps of Mercury bear witness to the history of contraction of a cooling planet. Previous models of the contraction of Mercury were for a one-dimensional mechanical model in which outermost crust of the planet is assumed to be elastic. However, the time-averaged surface temperature of Mercury varies strongly with both latitude and longitude due to the pattern of solar insolation over the planet, influenced by the planet's 3:2 spin-orbit resonant state, near-zero obliquity, and eccentric orbit about the Sun. The variation in surface temperature produces variations in lithospheric thickness and viscosity structure that may affect the patterns of deformation and faulting due to contraction. We explore this issue using a semi-analytic, spherical viscoelastic model that incorporates lateral variations of viscosity. Results suggest that temporal and spatial variations in lithospheric thickness during contraction affect the response of the planet. In particular, for contraction occurring relatively late in the presence of a thick lithosphere, the lithosphere deforms at the longest wavelengths, bowing outward where it is thinnest -at low latitudes for Mercury, particularly the areas around the equatorial "hot poles" that face the Sun at perihelion. We couple this model to thermal evolution calculations to simulate the effects of different core evolution scenarios. Topographic data returned by the Mercury Laser Altimeter (MLA) from MESSENGER's first flyby of Mercury in January demonstrate the existence of a long-wavelength slope along the equator, and many new lobate scarps were documented from MESSENGER images. After MESSENGER's second flyby in October, nearly the entire planet will have been imaged by spacecraft. Information on the long-wavelength shape of the planet, the distribution and orientation of lobate scarps, and their relation to other geological features, together with model results, will provide new constraints on the timing of global contraction

  3. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Dr. von Braun addresses a crowd celebrating in front of the Madison County Alabama Courthouse following the successful launch of Astronaut Alan Shepard (America's first astronaut in space) into space on a Mercury-Redstone Launch Vehicle, Freedom 7. Shepard's Mercury Spacecraft, was launched from Cape Canaveral. He reached a speed of 5200 mph. His flight lasted 15-1/2 minutes. May 5, 1961 (Photo: Courtesy of Huntsville/Madison County Public Library)

  4. Mercury Project

    NASA Image and Video Library

    1950-01-01

    A Mercury-Redstone launch vehicle awaits test-firing in the Redstone Test Stand during the late 1950s. Between 1953 and 1960, the rocket team at Redstone Arsenal in Huntsville, Alabama performed hundreds of test firings on the Redstone rocket, over 200 on the Mercury-Redstone vehicle configuration alone. It was this configuration which launched America's first two marned space missions, Freedom 7 and Liberty Bell 7,in 1961.

  5. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Astronaut Alan B. Shepard, Jr. awaits liftoff in the Freedom 7 Mercury spacecraft on May 5, 1961. This third flight of the Mercury-Redstone (MR-3) vehicle, developed by D. Wernher von Braun and the rocket team in Huntsville, Alabama, was the first marned space mission for the United States. During the 15-minute suborbital flight, Shepard reached an altitude of 115 miles and traveled 302 miles downrange.

  6. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Alan B. Shepard, Jr., America's first astronaut, stands in front of the Freedom 7 spacecraft shortly after completion of the third flight of the Mercury-Redstone (MR-3) vehicle, May 5, 1961. During the 15-minute suborbital flight, the Freedom 7 Mercury spacecraft, launched atop a modified Redstone rocket developed by Dr. Wernher von Braun and the rocket team in Huntsville, Alabama, reached an altitude of 115 miles and traveled 302 miles downrange.

  7. Chemical composition of Earth, Venus, and Mercury

    PubMed Central

    Morgan, John W.; Anders, Edward

    1980-01-01

    Model compositions of Earth, Venus, and Mercury are calculated from the premise that planets and chondrites underwent four identical fractionation processes in the solar nebula. Because elements of similar properties stay together in these processes, five constraints suffice to define the composition of a planet: mass of the core, abundance of U, and the ratios K/U, Tl/U, and FeO/(FeO + MgO). Complete abundance tables, and normative mineralogies, are given for all three planets. Review of available data shows only a few gross trends for the inner planets: FeO decreases with heliocentric distance, whereas volatiles are depleted and refractories are enriched in the smaller planets. Images PMID:16592930

  8. Chemical composition of Earth, Venus, and Mercury.

    PubMed

    Morgan, J W; Anders, E

    1980-12-01

    Model compositions of Earth, Venus, and Mercury are calculated from the premise that planets and chondrites underwent four identical fractionation processes in the solar nebula. Because elements of similar properties stay together in these processes, five constraints suffice to define the composition of a planet: mass of the core, abundance of U, and the ratios K/U, Tl/U, and FeO/(FeO + MgO). Complete abundance tables, and normative mineralogies, are given for all three planets. Review of available data shows only a few gross trends for the inner planets: FeO decreases with heliocentric distance, whereas volatiles are depleted and refractories are enriched in the smaller planets.

  9. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Estimated thickness of ejecta deposits compared to to crater rim heights. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The area of the continuous ejecta deposits on mercury was calculated to vary from 2.24 to 0.64 times the crater's area for those of diameter 40 km to 300 km. Because crater boundaries on the geologic map include the detectable continuous ejecta blanket, plains exterior to these deposits must consist of farther-flung ejecta (of that or other craters), or volcanic deposits flooding the intervening areas. Ejecta models are explored.

  10. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Estimated thickness of ejecta deposits compared to to crater rim heights. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leake, M. A.

    1982-01-01

    The area of the continuous ejecta deposits on mercury was calculated to vary from 2.24 to 0.64 times the crater's area for those of diameter 40 km to 300 km. Because crater boundaries on the geologic map include the detectable continuous ejecta blanket, plains exterior to these deposits must consist of farther-flung ejecta (of that or other craters), or volcanic deposits flooding the intervening areas. Ejecta models are explored.

  11. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie; James, John T.; McCoy, Torin; Garcia, Hector

    2010-01-01

    Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed through the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may be completely vaporized when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. Using an existing study, we estimated mercury vapor releases from lamps that are not in operation during missions lasting less than or equal to 30 days; whereas we conservatively assumed complete vaporization from lamps that are operating or being used during missions lasing more than 30 days. Based on mercury toxicity, the Johnson Space Center's Toxicology Group recommends stringent safety controls and verifications for any hardware containing elemental mercury that could yield airborne mercury vapor concentrations greater than 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting less than or equal to 30 days, or concentrations greater than 0.01 mg/m3 for exposures lasting more than 30 days.

  12. Exploring Planet Sizes

    NASA Image and Video Library

    This lesson combines a series of activities to compare models of the size of Earth to other planets and the distances to other planets. Activities highlight space missions to other planets in our s...

  13. 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.

  14. Updating the Magnitudes of the Planets in The Astronomical Almanac

    DTIC Science & Technology

    2003-01-01

    USNO/AA Technical Note 2003-04 Updating the Magnitudes of the Planets in The Astronomical Almanac James L. Hilton The content of this Tech...the magnitudes of Mercury and Venus used in the AsA 2005 and 2006. Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden...SUBTITLE Updating The Magnitudes Of The Planets In The Astronomical Almanac 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

  15. JANUS, A Proposed Pathfinder Mission to Mercury

    NASA Astrophysics Data System (ADS)

    Curtis, S. A.; Clark, P. E.; Giles, B.; Eyerman, C.; Marr, G.; Winterhalter, D.; Janus Mercury Pathfinder Mission Team

    1998-09-01

    Despite the Mariner 10 flybys and decades of ground-based observations, the planet Mercury remains the most poorly understood inner planet although it could potentially provide essential information on the evolution and origin of the solar system. JANUS, a mission proposed for the NASA Discovery Program, is an extremely fast, low cost, low risk, multiple flyby, four platform pathfinder to Mercury which would provide this essential data and complete the exploration of both hemispheres. JANUS studies Mercury and its environment as a system by simultaneously exploring its interior, surface, atmosphere, and magnetosphere. After a direct transfer orbit from Earth, the first dayside equatorial encounter with Mercury is 115 days post-launch, and includes the release of three Remote Experiment Packages (REPs) targeted for north and south poles and the magnetotail. This encounter provides the fist direct compositional measurements of Mercury and simultaneous multi-point modeling of its magnetic field. Perihelion engine burn following this encounter places the main spacecraft in a 264 day orbit allowing view of alternate sunlit faces of Mercury at each encounter. By the end of the second encounter (one year post-launch), the first photospectral map of the entire planet and a completed set of previously mission compositional constraints for inner solar system, core, and planetary formation is produced. The third encounter, less than two years post-launch, takes the spacecraft over the south pole in search of polar volatiles. JANUS features an experienced, integrated science team and a robust instrumentation package: imaging, X-ray, UV, and neutron spectrometers, energetic particle and electric field detectors, magnetometer, low energy plasma analyzer, and search coil on the main spacecraft, and duplicates of the last three instruments on each REP. JANUS is a true pathfinder, completing the primary exploration of Mercury and forging the path for future GSFC/JPL partnerships.

  16. PLANET-PLANET SCATTERING IN PLANETESIMAL DISKS

    SciTech Connect

    Raymond, Sean N.; Armitage, Philip J.; Gorelick, Noel

    2009-07-10

    We study the final architecture of planetary systems that evolve under the combined effects of planet-planet and planetesimal scattering. Using N-body simulations we investigate the dynamics of marginally unstable systems of gas and ice giants both in isolation and when the planets form interior to a planetesimal belt. The unstable isolated systems evolve under planet-planet scattering to yield an eccentricity distribution that matches that observed for extrasolar planets. When planetesimals are included the outcome depends upon the total mass of the planets. For M {sub tot} {approx}> 1 M{sub J} the final eccentricity distribution remains broad, whereas for M {sub tot} {approx}< 1 M{sub J} a combination of divergent orbital evolution and recircularization of scattered planets results in a preponderance of nearly circular final orbits. We also study the fate of marginally stable multiple planet systems in the presence of planetesimal disks, and find that for high planet masses the majority of such systems evolve into resonance. A significant fraction leads to resonant chains that are planetary analogs of Jupiter's Galilean satellites. We predict that a transition from eccentric to near-circular orbits will be observed once extrasolar planet surveys detect sub-Jovian mass planets at orbital radii of a {approx_equal} 5-10 AU.

  17. The Giant Planet Satellite Exospheres

    NASA Astrophysics Data System (ADS)

    McGrath, M. A.

    2014-12-01

    Exospheres are relatively common in the outer solar system among the moons of the gas giant planets. They span the range from very tenuous, surface-bounded exospheres (e.g., Rhea, Dione) to quite robust exospheres with exobase above the surface (e.g., Io, Triton), and include many intermediate cases (e.g., Europa, Ganymede, Enceladus). The exospheres of these moons exhibit an interesting variety of sources, from surface sputtering, to frost sublimation, to active plumes, and also well illustrate another common characteristic of the outer planet satellite exospheres, namely, that the primary species often exists both as a gas in atmosphere, and a condensate (frost or ice) on the surface. As described by Yelle et al. (1995) for Triton, "The interchange of matter between gas and solid phases on these bodies has profound effects on the physical state of the surface and the structure of the atmosphere." A brief overview of the exospheres of the outer planet satellites will be presented, including an inter-comparison of these satellites exospheres with each other, and with the exospheres of the Moon and Mercury.

  18. The Giant Planet Satellite Exospheres

    NASA Technical Reports Server (NTRS)

    McGrath, Melissa A.

    2014-01-01

    Exospheres are relatively common in the outer solar system among the moons of the gas giant planets. They span the range from very tenuous, surface-bounded exospheres (e.g., Rhea, Dione) to quite robust exospheres with exobase above the surface (e.g., lo, Triton), and include many intermediate cases (e.g., Europa, Ganymede, Enceladus). The exospheres of these moons exhibit an interesting variety of sources, from surface sputtering, to frost sublimation, to active plumes, and also well illustrate another common characteristic of the outer planet satellite exospheres, namely, that the primary species often exists both as a gas in atmosphere, and a condensate (frost or ice) on the surface. As described by Yelle et al. (1995) for Triton, "The interchange of matter between gas and solid phases on these bodies has profound effects on the physical state of the surface and the structure of the atmosphere." A brief overview of the exospheres of the outer planet satellites will be presented, including an inter-comparison of these satellites exospheres with each other, and with the exospheres of the Moon and Mercury.

  19. Mercury - Internal structure and thermal evolution

    NASA Technical Reports Server (NTRS)

    Siegfried, R. W., II; Solomon, S. C.

    1974-01-01

    Mercury's thermal evolution and internal structure are modeled based on the planet's gross physical properties (which imply a high metallic iron content) and predictions for its chemistry made from the Lewis-Cameron model of condensation of the primitive solar nebula (which implies that Mercury may be composed only of those materials that condensed at temperatures near that of metallic iron condensation in the cooling nebula). Various heat sources, initial temperatures, and thermal conductivities are considered for a homogeneous model and a differentiated two-layer model. Density distributions are calculated from the mean density and estimates of the present-day temperature. The moment of inertia and the hydrostatic value of the second degree harmonic coefficient of Mercury's gravity field are found for the differentiated and undifferentiated models. These results should be useful for preliminary interpretation of the Mariner 10 measurements of Mercury's gravitational field.

  20. Imaging During MESSENGER's Second Flyby of Mercury

    NASA Astrophysics Data System (ADS)

    Chabot, N. L.; Prockter, L. M.; Murchie, S. L.; Robinson, M. S.; Laslo, N. R.; Kang, H. K.; Hawkins, S. E.; Vaughan, R. M.; Head, J. W.; Solomon, S. C.; MESSENGER Team

    2008-12-01

    During MESSENGER's second flyby of Mercury on October 6, 2008, the Mercury Dual Imaging System (MDIS) will acquire 1287 images. The images will include coverage of about 30% of Mercury's surface not previously seen by spacecraft. A portion of the newly imaged terrain will be viewed during the inbound portion of the flyby. On the outbound leg, MDIS will image additional previously unseen terrain as well as regions imaged under different illumination geometry by Mariner 10. These new images, when combined with images from Mariner 10 and from MESSENGER's first Mercury flyby, will enable the first regional- resolution global view of Mercury constituting a combined total coverage of about 96% of the planet's surface. MDIS consists of both a Wide Angle Camera (WAC) and a Narrow Angle Camera (NAC). During MESSENGER's second Mercury flyby, the following imaging activities are planned: about 86 minutes before the spacecraft's closest pass by the planet, the WAC will acquire images through 11 different narrow-band color filters of the approaching crescent planet at a resolution of about 5 km/pixel. At slightly less than 1 hour to closest approach, the NAC will acquire a 4-column x 11-row mosaic with an approximate resolution of 450 m/pixel. At 8 minutes after closest approach, the WAC will obtain the highest-resolution multispectral images to date of Mercury's surface, imaging a portion of the surface through 11 color filters at resolutions of about 250-600 m/pixel. A strip of high-resolution NAC images, with a resolution of approximately 100 m/pixel, will follow these WAC observations. The NAC will next acquire a 15-column x 13- row high-resolution mosaic of the northern hemisphere of the departing planet, beginning approximately 21 minutes after closest approach, with resolutions of 140-300 m/pixel; this mosaic will fill a large gore in the Mariner 10 data. At about 42 minutes following closest approach, the WAC will acquire a 3x3, 11-filter, full- planet mosaic with an

  1. Thermal evolution of Mercury as constrained by MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Michel, Nathalie C.; Hauck, Steven A.; Solomon, Sean C.; Phillips, Roger J.; Roberts, James H.; Zuber, Maria T.

    2013-05-01

    observations of Mercury by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft provide new constraints on that planet's thermal and interior evolution. Specifically, MESSENGER observations have constrained the rate of radiogenic heat production via measurement of uranium, thorium, and potassium at the surface, and identified a range of surface compositions consistent with high-temperature, high-degree partial melts of the mantle. Additionally, MESSENGER data have placed new limits on the spatial and temporal variation in volcanic and tectonic activity and enabled determination that the planet's core is larger than previously estimated. Because Mercury's mantle layer is also thinner than previously thought, this result gives greater likelihood to the possibility that mantle convection is marginally supercritical or even that the mantle is not convecting. We simulate mantle convection and magma generation within Mercury's mantle under two-dimensional axisymmetry and a broad range of conditions to understand the implications of MESSENGER observations for the thermal evolution of the planet. These models demonstrate that mantle convection can persist in such a thin mantle for a substantial portion of Mercury's history, and often to the present, as long as the mantle is thicker than ~300 km. We also find that magma generation in Mercury's convecting mantle is capable of producing widespread magmas by large-degree partial melting, consistent with MESSENGER observations of the planet's surface chemistry and geology.

  2. Interior Structure and Evolution of the Planets

    NASA Astrophysics Data System (ADS)

    Hubbard, W. B.

    Basic Concepts Presumed initial composition Comparison with stellar structure Structure of Cold Bodies T=O thermodynamics The P--> infinity limit (white dwarfs) Finite pressure theories Experimental data at high pressure The radius-mass diagram Heat Flow Review of data The Kelvin mechanism Differentiation Radioactivity Tidal Heating Other Diagnostics of Interior Structure Response to rotation Tidal response Magnetic field The Terrestrial Planets The earth and the moon Mercury Venus Mars Summary The Jovian Planets Jupiter A fundamental solar composition reference? Thermal structure and heat flow Evolution of Jupiter Saturn Differences with Jupiter Heat flow Uranus and Neptune Key differences with Jupiter and with each other Thermal structure and heat flow Jovian Planet Satellites Io's heat flow and its relation to Jupiter's structure The Galilean satellites and their relation to Jupiter's origin Conclusion References

  3. Testing Planet Formation Models with Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Ford, E. B.

    The first discoveries of extrasolar planets demonstrated that nature produces a much greater diversity of planetary systems than astronomers had anticipated. In an attempt to explain these surprises, theorists have proposed numerous generalizations to the classical model of planet formation. Recently, researchers have begun testing some of these theories by comparing the predicted distributions of planet periods, eccentricities, and masses to those of the observed population of extrasolar planets. Such comparisons are becoming increasingly powerful thanks to the increasing number of known planets, improving measurement precision, increasing temporal baselines, and improving capability to control for detection biases. Here, we discuss some of the orbital properties of the extrasolar planet population based on a systematic analysis of radial velocity planets and discuss implications for the formation and evolution of planetary systems.

  4. How is Mercury's dynamo powered?

    NASA Astrophysics Data System (ADS)

    Cox, G. A.; Delbridge, B. G.; Irving, J. C. E.; Matsui, H.; McDonough, W. F.; Rose, I.; Shahar, A.; Wahl, S. M.

    2014-12-01

    One of the more surprising findings of the MESSENGER spacecraft is the confirmation that the smallest terrestrial planet has an internally generated, dipolar magnetic field, which is likely driven by a combination of thermal and compositional buoyancy sources. This observation places constraints on the thermal and energetic state of Mercury's large iron core and on mantle dynamics because dynamo operation is strongly dependent on the amount of heat extracted from the core by the mantle. However, other observations point to several factors that should inhibit a present-day dynamo. These include physical constraints on a thin, possibly non-convecting mantle, as well as properties of liquid iron alloys that promote compositional stratification in the core. We consider a range of self-consistent internal structures, core compositions and thermal evolution models that are also consistent with observational constraints, and assess the circumstances under which a dynamo is permitted to operate in Mercury's core. We present the thermal evolution models, 1D parameterized convection models and planetary entropy calculations. We attempt to account for the large uncertainties on some parameters by considering various end member cases. We examine the thermal and magnetic implications of a long-lived lateral temperature difference resulting from Mercury's orbital resonance and how it may play a role in driving the planetary dynamo. We compare simulations of mantle heat flow using the ASPECT convection code to predictions from the parameterized models and produce heat flow maps at the CMB. To represent fluid dynamics and magnetic field generation inside Mercury's core, a numerical dynamo model is performed by using the obtained heat flux maps. Lastly, we also investigate the seismic observability of the different structural models of Mercury to determine the extent to which any future single-seismometer mission will be able to provide alternative insights into Mercury's internal

  5. Sodium Velocity Maps on Mercury

    NASA Technical Reports Server (NTRS)

    Potter, A. E.; Killen, R. M.

    2011-01-01

    The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

  6. On volcanism and thermal tectonics on one-plate planets

    NASA Technical Reports Server (NTRS)

    Solomon, S. C.

    1978-01-01

    For planets with a single global lithospheric shell or 'plate', the thermal evolution of the interior affects the surface geologic history through volumetric expansion and the resultant thermal stress. Interior warming of such planets gives rise to extensional tectonics and a lithospheric stress system conductive to widespread volcanism. Interior cooling leads to compressional tectonics and lithospheric stresses that act to shut off surface volcanism. On the basis of observed surface tectonics, it is concluded that the age of peak planetary volume, the degree of early heating, and the age of youngest major volcanism on the one-plate terrestrial planets likely decrease in the order Mercury, Moon, Mars.

  7. Experimental investigation into the thermal and magmatic evolution of Mercury

    NASA Astrophysics Data System (ADS)

    Vander Kaaden, Kathleen E.

    During the time that the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was in orbit around the innermost planet, new and exciting results regarding the planets structure, chemical makeup, and diverse surface were revealed, confirming that Mercury is a geochemical endmember among the terrestrial planets. Data from this mission, more specifically data from the X-Ray Spectrometer and Gamma-Ray Spectrometer onboard MESSENGER, has been used to provide insight into the thermal and magmatic evolution of Mercury. This dissertation consists of five chapters that, as a whole, have substantially increased our knowledge about Mercury through a high pressure and high temperature experimental investigation. First, we identified nine distinct geochemical regions that have characteristic major element compositions. We computed silicate and sulfide mineralogy of these regions and petrologically classified them according to IUGS specifications. The diversity of the rocks and minerals on Mercury was then compared to other planetary bodies revealing the wide range in diversity of the mercurian surface. Second, we conducted sink-float experiments on a melt composition similar to the composition of the largest volcanic field on the planet to provide insight into crust formation on Mercury. These results suggested a primary floatation crust composed of graphite is possible given a magma ocean event on Mercury. Third, we experimentally determined the phase assemblages associated with the largest volcanic field on the planet. From this data we were able to provide insight into eruption scenarios that produced the northern volcanic plains on Mercury. Fourth, we determined the sulfide concentration at sulfide saturation in mercurian-like melts by conducting sulfide solubility experiments on a synthetic rock composition matching the northern volcanic plains. These results indicated that the high amounts of sulfur on the surface of Mercury measured by

  8. A Google Earth Grand Tour of the Terrestrial Planets

    ERIC Educational Resources Information Center

    De Paor, Declan; Coba, Filis; Burgin, Stephen

    2016-01-01

    Google Earth is a powerful instructional resource for geoscience education. We have extended the virtual globe to include all terrestrial planets. Downloadable Keyhole Markup Language (KML) files (Google Earth's scripting language) associated with this paper include lessons about Mercury, Venus, the Moon, and Mars. We created "grand…

  9. A Google Earth Grand Tour of the Terrestrial Planets

    ERIC Educational Resources Information Center

    De Paor, Declan; Coba, Filis; Burgin, Stephen

    2016-01-01

    Google Earth is a powerful instructional resource for geoscience education. We have extended the virtual globe to include all terrestrial planets. Downloadable Keyhole Markup Language (KML) files (Google Earth's scripting language) associated with this paper include lessons about Mercury, Venus, the Moon, and Mars. We created "grand…

  10. Mercury's resonant rotation from secular orbital elements

    NASA Astrophysics Data System (ADS)

    Stark, Alexander; Oberst, Jürgen; Hussmann, Hauke

    2015-11-01

    We used recently produced Solar System ephemerides, which incorporate 2 years of ranging observations to the MESSENGER spacecraft, to extract the secular orbital elements for Mercury and associated uncertainties. As Mercury is in a stable 3:2 spin-orbit resonance, these values constitute an important reference for the planet's measured rotational parameters, which in turn strongly bear on physical interpretation of Mercury's interior structure. In particular, we derive a mean orbital period of (87.96934962 ± 0.00000037) days and (assuming a perfect resonance) a spin rate of (6.138506839± 0.000000028)°/day. The difference between this rotation rate and the currently adopted rotation rate (Archinal et al. in Celest Mech Dyn Astron 109(2):101-135, 2011. doi:10.1007/s10569-010-9320-4), corresponds to a longitudinal displacement of approx. 67 m per year at the equator. Moreover, we present a basic approach for the calculation of the orientation of the instantaneous Laplace and Cassini planes of Mercury. The analysis allows us to assess the uncertainties in physical parameters of the planet, when derived from observations of Mercury's rotation.

  11. A Laser-Ablation Mass Spectrometer for the Surface of Mercury

    NASA Astrophysics Data System (ADS)

    Whitby, J. A.; Rohner, U.; Benz, W.; Wurz, P.

    2003-03-01

    A snapshot of the development of an instrument capable of making in situ elemental and isotopic measurements on the surface of a rocky planet or planetesimal. Designed with the BepiColombo mission to Mercury in mind.

  12. Questions about Mercury's role in comparative planetary geophysics

    NASA Technical Reports Server (NTRS)

    Chapman, C. R.; Weidenschilling, S. J.; Davis, D. R.; Greenberg, R.; Leake, M. A.

    1985-01-01

    Problems which have arisen in formulating a mutually consistent picture of Mercury's evolution are outlined. It appears that one or more of the following widely adopted assumptions are wrong about Mercury: (1) its original composition at least approximately resulted from equilibrium condensation; (2) its magnetic field arises from a still-active dynamo; (3) its thermal evolution should have yielded early core formation followed by cooling and a global contraction approaching 20 km in the planet's radius; (4) Mercury's surface is basaltic and the intercrater plains are of volcanic origin. It is suggested that Mercury's role in comparative planetology be reevaluated in the context of an alternative timescale based on the possibility that Mercury was subjected to a continuing source of cratering projectiles over recent aeons, which have not impacted the other terrestrial planets. Although such vulcanoids have not yet been discovered, the evolution of Mercury's orbit due to secular perturbations could well have led to a prolonged period of sweeping out any intra-Mercurian planetesimals that were originally present. Mercury's surface could be younger than previously believed, which explains why Mercury's core is still molten.

  13. Mercury, elemental

    Integrated Risk Information System (IRIS)

    Mercury , elemental ; CASRN 7439 - 97 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  14. Mercury Project

    NASA Image and Video Library

    1962-02-20

    Astronaut John Glenn in the Friendship 7 capsule during the first manned orbital flight, the MA-6 mission. Boosted by the Mercury-Atlas vehicle, a modified Atlas (intercontinental ballistic missile), the MA-6 mission lasted for 5 hours and orbited the Earth three times.

  15. Mercury Project

    NASA Image and Video Library

    1962-02-20

    The launch of the MA-6, Friendship 7, on February 20, 1962. Boosted by the Mercury-Atlas vehicle, a modified Atlas Intercontinental Ballistic Missile (ICBM), Friendship 7 was the first U.S. marned orbital flight and carried Astronaut John H. Glenn into orbit. Astronaut Glenn became the first American to orbit the Earth.

  16. Mercury Project

    NASA Image and Video Library

    1959-09-01

    An Atlas launch vehicle carrying the Big Joe capsule leaves its launching pad on a 2,000-mile ballistic flight to the altitude of 100 miles. The Big Joe capsule is a boilerplate model of the marned orbital capsule under NASA's Project Mercury. The capsule was recovered and studied for the effect of re-entry heat and other flight stresses.

  17. Mercury Project

    NASA Image and Video Library

    1959-04-27

    The group portrait of the original seven astronauts for the Mercury Project. NASA selected its first seven astronauts on April 27, 1959. Left to right at front: Walter M. Wally Schirra, Donald K. Deke Slayton, John H. Glenn, Jr., and Scott Carpenter. Left to right at rear: Alan B. Shepard, Virgil I. Gus Grissom, and L. Gordon Cooper, Jr.

  18. Mercury Project

    NASA Image and Video Library

    1963-05-16

    Astronaut Gordon Cooper leaves the Faith 7 (MA-9) spacecraft after a successful recovery operation. The MA-9 mission, the last flight of the Mercury Project, was launched on May 15, 1963, orbited the Earth 22 times, and lasted for 1-1/2 days.

  19. Mercury Project

    NASA Image and Video Library

    1963-05-15

    Astronaut Gordon Cooper leaves the Faith 7 (MA-9) spacecraft after a successful recovery operation. The MA-9 mission, the last flight of the Mercury Project, was launched on May 15, 1963, orbited the Earth 22 times, and lasted for 1-1/2 days.

  20. Mercury Project

    NASA Image and Video Library

    2004-04-15

    The original seven astronauts for the Mercury Project pose in front of an Air Force Jet. From left to right: Scott Carpenter, L. Gordon Cooper, John H. Glenn, Virgil I. Gus Grissom, Walter M. Wally Schirra, Alan B. Shepard, and Donald K. Deke Slayton.

  1. Mercury Project

    NASA Image and Video Library

    1960-01-21

    The launch of the Little Joe booster for the LJ1B mission on the launch pad from the wallops Flight Facility, Wallops Island, Virginia, on January 21, 1960. This mission achieved the suborbital Mercury capsule test, testing of the escape system, and biomedical tests by using a monkey, named Miss Sam.

  2. Mercury Project

    NASA Image and Video Library

    1960-01-21

    The Little Joe launch vehicle for the LJ1 mission on the launch pad at the wallops Flight Facility, Wallops Island, Virginia, on January 21, 1960. This mission achieved the suborbital Mercury cupsule test, testing of the escape system, and biomedical tests by using a monkey, named Miss Sam.

  3. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Astronaut Alan Shepard underwent a physical examination prior to the first marned suborbital flight. Freedom 7 carrying Astronaut Alan Shepard, boosted by the Mercury-Redstone launch vehicle, lifted off on May 5, 1961. Astronaut Shepard became the first American in space.

  4. Mercury Project

    NASA Image and Video Library

    1961-01-01

    Astronaut Alan Shepard fitted with space suit prior to the first marned suborbital flight. Freedom 7, carrying Astronaut Alan Shepard, boosted by the Mercury-Redstone launch vehicle, lifted off on May 5, 1961. Astronaut Shepard became the first American in space.

  5. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Astronaut Alan B. Shepard, Jr. during suiting for the first manned suborbital flight, MR-3 mission. The Freedom 7 spacecraft, carrying the first American, Astronaut Shepard and boosted by the Mercury-Redstone launch vehicle, lifted off on May 5, 1961.

  6. Mercury Project

    NASA Image and Video Library

    1961-05-05

    This photo depicts the recovery operations of the MR-3 mission. Astronaut Alan Shepard was picked up by a U.S. Marine helicopter after the completion of the first marned suborbital flight by MR-3 (Mercury-Redstone) with the Freedom 7 capsule.

  7. A Christmas Crater from Mercury

    NASA Image and Video Library

    2017-09-27

    Release Date: December 21, 2011 The crater at the center of this image is named Dickens, after Charles Dickens, the English novelist who lived from 1812 to 1870. Among Dickens' famous works is A Christmas Carol, the story of Bob Cratchit, his family, and horrible boss Mr. Scrooge. Scientists studying Mercury might consider the Mariner 10 mission to be Christmas Past, MESSENGER to be Christmas Present, and the European Bepi-Colombo mission to be Christmas Yet To Come. This image was acquired as part of MDIS's high-resolution surface morphology base map. The surface morphology base map will cover more than 90% of Mercury's surface with an average resolution of 250 meters/pixel (0.16 miles/pixel or 820 feet/pixel). Images acquired for the surface morphology base map typically have off-vertical Sun angles (i.e., high incidence angles) and visible shadows so as to reveal clearly the topographic form of geologic features. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. Visit the Why Mercury? section of this website to learn more about the key science questions that the MESSENGER mission is addressing. During the one-year primary mission, MDIS is scheduled to acquire more than 75,000 images in support of MESSENGER's science goals. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington 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

  8. Mickey Mouse Spotted on Mercury!

    NASA Image and Video Library

    2017-09-27

    NASA image acquired: June 03, 2012 This scene is to the northwest of the recently named crater Magritte, in Mercury's south. The image is not map projected; the larger crater actually sits to the north of the two smaller ones. The shadowing helps define the striking "Mickey Mouse" resemblance, created by the accumulation of craters over Mercury's long geologic history. This image was acquired as part of MDIS's high-incidence-angle base map. The high-incidence-angle base map is a major mapping activity in MESSENGER's extended mission and complements the surface morphology base map of MESSENGER's primary mission that was acquired under generally more moderate incidence angles. High incidence angles, achieved when the Sun is near the horizon, result in long shadows that accentuate the small-scale topography of geologic features. The high-incidence-angle base map is being acquired with an average resolution of 200 meters/pixel. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. Visit the Why Mercury? section of this website to learn more about the key science questions that the MESSENGER mission is addressing. During the one-year primary mission, MESSENGER acquired 88,746 images and extensive other data sets. MESSENGER is now in a yearlong extended mission, during which plans call for the acquisition of more than 80,000 additional images to support MESSENGER's science goals. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington 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

  9. Television observations of Mercury by Mariner 10

    NASA Technical Reports Server (NTRS)

    Murray, B. C.; Belton, M. J. S.; Danielson, E. G.; Davies, M. E.; Gault, D. E.; Hapke, B.; Oleary, B.; Strom, R. G.; Suomi, V.; Trask, N.

    1977-01-01

    The morphology and optical properties of the surface of Mercury resemble those of the Moon in remarkable detail, recording a very similar sequence of events; chemical and mineralogical similarity of the outer layers is implied. Mercury is probably a differentiated planet with an iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of any landform is found. Large-scale scarps and ridges unlike lunar or Martian features may reflect a unique period of planetary compression near the end of heavy bombardment, perhaps related to contraction of the core.

  10. The Origin of Mercury

    NASA Astrophysics Data System (ADS)

    Benz, W.; Anic, A.; Horner, J.; Whitby, J. A.

    2007-10-01

    Mercury’s unusually high mean density has always been attributed to special circumstances that occurred during the formation of the planet or shortly thereafter, and due to the planet’s close proximity to the Sun. The nature of these special circumstances is still being debated and several scenarios, all proposed more than 20 years ago, have been suggested. In all scenarios, the high mean density is the result of severe fractionation occurring between silicates and iron. It is the origin of this fractionation that is at the centre of the debate: is it due to differences in condensation temperature and/or in material characteristics (e.g. density, strength)? Is it because of mantle evaporation due to the close proximity to the Sun? Or is it due to the blasting off of the mantle during a giant impact? In this paper we investigate, in some detail, the fractionation induced by a giant impact on a proto-Mercury having roughly chondritic elemental abundances. We have extended the previous work on this hypothesis in two significant directions. First, we have considerably increased the resolution of the simulation of the collision itself. Second, we have addressed the fate of the ejecta following the impact by computing the expected reaccretion timescale and comparing it to the removal timescale from gravitational interactions with other planets (essentially Venus) and the Poynting Robertson effect. To compute the latter, we have determined the expected size distribution of the condensates formed during the cooling of the expanding vapor cloud generated by the impact. We find that, even though some ejected material will be reaccreted, the removal of the mantle of proto-Mercury following a giant impact can indeed lead to the required long-term fractionation between silicates and iron and therefore account for the anomalously high mean density of the planet. Detailed coupled dynamical chemical modeling of this formation mechanism should be carried out in such a way as to

  11. Impact vaporization as a source of calcium in Mercury's exosphere

    NASA Astrophysics Data System (ADS)

    Killen, R.; Hahn, J.

    2014-07-01

    Mercury is surrounded by a surface-bounded exosphere with six known components, H, He, Na, K, Ca, and Mg. Both Ca and Mg are of extreme temperature and with a source concentrated on the dawn side. Calcium has been observed in Mercury's exosphere for the past two decades, having been discovered by Bida et al. (2000) using the Keck telescope on Mauna Kea. Observations of the Ca exosphere of Mercury show that the Ca abundance varies in a periodic way with Mercury's orbital longitude (Burger et al., 2014). Note that Mercury's orbit is quite eccentric, e=0.2, so this planet's radial excursions through the interplanetary dust particle (IDP) complex are substantial, ± 20 %, and the observed Ca signal is in fact correlated with the planet's periodic heliocentric distance. It has been suggested that impact vaporization of interplanetary dust striking the planet might be responsible for the periodic variations in Mercury's exospheric Na (Kameda et al., 2009). Note that if IDP impacts are the dominant source of Ca then one might expect the exospheric Ca signal to be maximal when Mercury is at periapse and the heliocentric dust density would be greatest. However the observed Ca signal is instead maximal when Mercury has traveled about 25 degrees past periapse, and two possible explanations come to mind. (i.) Mercury has a fairly high inclination, 7 degrees, so its vertical motion might be a fair fraction of the dust-complex's vertical thickness. If so then the site of maximum IDP density along Mercury's orbit will be sensitive to the longitude where Mercury's vertical motion carries it across the dust-disk's midplane. (ii.) Alternatively, Mercury's seasonal Ca signal might be influenced by a cometary meteor shower, which would occur if the planet passes through a cometary dust trail; such trails are composed of relatively large dust grains that slowly drift radially due to the Poynting-Robertson drag. This dust is still confined to the comet's orbital plane, so a meteor

  12. Mercury's Weather-Beaten Surface: Understanding Mercury in the Context of Lunar and Asteroid Space Weathering Studies

    NASA Technical Reports Server (NTRS)

    Dominque, Deborah L.; Chapman, Clark R.; Killen, Rosemary M.; Zurbuchen, Thomas H.; Gilbert, Jason A.; Sarantos, Menelaos; Benna, Mehdi; Slavin, James A.; Orlando, Thomas M.; Schriver, David; hide

    2011-01-01

    Understanding the composition of Mercury's crust is key to comprehending the formation of the planet. The regolith, derived from the crustal bedrock, has been altered via a set of space weathering processes. These processes are the same set of mechanisms that work to form Mercury's exosphere, and are moderated by the local space environment and the presence of an intrinsic planetary magnetic field. The alterations need to be understood in order to determine the initial crustal compositions. The complex interrelationships between Mercury's exospheric processes, the space environment, and surface composition are examined and reviewed. The processes are examined in the context of our understanding of these same processes on the lunar and asteroid regoliths. Keywords: Mercury (planet) Space weathering Surface processes Exosphere Surface composition Space environment 3

  13. Indicators: Sediment Mercury

    EPA Pesticide Factsheets

    Sediment mercury is mercury that has become embedded into the bottom substrates of aquatic ecosystems. Mercury is a common pollutant of aquatic ecosystems and it can have a substantial impact on both human and wildlife health.

  14. Mercury's South Polar Region

    NASA Image and Video Library

    This animation shows 89 wide-angle camera (WAC) images of Mercury’s south polar region acquired by the Mercury Dual Imaging System (MDIS) over one complete Mercury solar day (176 Earth days). Thi...

  15. The Mercury exosphere after MESSENGER

    NASA Astrophysics Data System (ADS)

    Killen, Rosemary; McClintock, William; Vervack, Ronald; Merkel, Aimee; Burger, Matthew; Cassidy, Timothy; Sarantos, Menelaos

    2016-07-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft observed sodium, calcium and magnesium emisison in Mercury's exosphere on a near-daily basis for >16 Mercury years. The MASCS observations showed that calcium in Mercury's exosphere is persistently concentrated in the dawn hemisphere and is of extreme temperature (>50,000 K). The column abundance varies seasonally, and is extremely repeatable each Mercury year. In addition, the calcium exhibits a persistent maximum not at perihelion but 20° after perihelion, an enhancement that was shown to be coincident with the probable intersection of Mercury's orbit with a dust stream originating at Comet Encke. Any mechanism producing the Mercurian Ca exosphere must explain the facts that the Ca is extremely hot, that it is seen almost exclusively on the dawnside of the planet, and that its content varies seasonally, not sporadically. Energization of the Ca atoms was suggested to originate through dissociation of Ca-bearing molecules ejected by meteoritic impacts. Magnesium was also observed on a daily basis throughout the MESSENGER orbital phase. Mg has its own spatial and temporal pattern, peaking at mid-morning instead of early morning like Ca, and exhibiting a warm thermal profile, about 5000 K, unlike the extreme temperature of Ca which is an order of magnitude hotter. Although Mercury's sodium exosphere has been observed from the ground for many decades, the MASCS observations showed that, like calcium, the sodium exosphere is dominated by seasonal variations, not sporadic variations. However a conundrum exists as to why ground-based observations show highly variable high-latitude variations that eluded the MASCS. The origin of a persistent south polar enhancement has not been explained. The more volatile element, Na, is again colder, about 1200 K, but not thermally accommodated to the surface temperature. A

  16. Mercury's interior from MESSENGER geodetic measurements

    NASA Astrophysics Data System (ADS)

    Genova, Antonio; Mazarico, Erwan; Goossens, Sander; Lemoine, Frank G.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.; Solomon, Sean C.

    2016-04-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft completed more than 4 years of operations in orbit about Mercury. One of the main mission goals was the determination of the interior structure of Mercury enabled by geodetic observations of the topography, gravity field, rotation, and tides by the Mercury Laser Altimeter (MLA) and radio science system. MLA acquired over 25 million individual measurements of Mercury's shape that are mostly limited to the northern hemisphere because of MESSENGER's eccentric orbit. However, the lack of laser altimetry in the southern hemisphere has been partly compensated by ˜400 occultations of spacecraft radio signals. X-band radio tracking data collected by the NASA Deep Space Network (DSN) allowed the determination of Mercury's gravity field to spherical harmonic degree and order 100, the planet's obliquity, and the Love number k2. The combination of altimetry and radio measurements provides a powerful tool for the investigation of Mercury's orientation and tides, which enable a better understanding of the interior structure of the planet. The MLA measurements have been assembled into a digital elevation model (DEM) of the northern hemisphere. We then used individual altimetric measurements from the spacecraft for orbit determination, together with the radio tracking, over a continuous span of time using a batch least-squares filter. All observations were combined to recover directly the gravity field coefficients, obliquity, librations, and tides by minimizing the discrepancies between the computed observables and actual measurements. We will present the estimated 100×100 gravity field model, the obliquity, the Love number k2, and, for the first time, the tidal phase lag φ and the amplitude of the longitudinal libration from radio and altimetry data. The k2 phase provides information on Mercury's dissipation and mantle viscosity and allows a determination of the Q factor. A refinement of

  17. MESSENGER: The Discovery Mission to Mercury

    NASA Astrophysics Data System (ADS)

    McNutt, R. L.; Solomon, S. C.; Gold, R. E.; Domingue, D. L.

    2004-12-01

    NASA's MErcury, Surface, Space ENvironment, GEochenistry, and Ranging (MESSENGER) spacecraft, launched on 3 August 2004, has begun its voyage to initiate a new era in our understanding of the terrestrial planets. The mission, spacecraft, and payload are designed to answer six fundamental questions regarding the innermost planet: What planetary formational processes led to Mercury's high metal/silicate ratio? What is the geological history of Mercury? What are the nature and origin of Mercury's magnetic field? What are the structure and state of Mercury's core? What are the radar-reflective materials at Mercury's poles? What are the important volatile species and their sources and sinks on and near Mercury? Planet formational hypotheses will be tested by measuring the surface abundances of major elements by X-ray and gamma-ray spectrometry. The geological history will be determined from high-resolution color imaging of the heavily cratered highlands, intercrater plains, and smooth plains. MESSENGER will provide detailed views of both the Caloris basin and its antipodal terrain. Topographic, mineralogical, and elemental abundance data will be used to seek evidence of volcanic features and units. Measurement of Mercury's magnetic field and its interaction with the solar wind will distinguish the intrinsic dipole and quadrupole components while separating these from the current systems driven by solar-wind-induced convection. The structure of the internal field will put constraints on dynamo models. Such models will also be constrained by measuring Mercury's libration to determine the extent of a fluid outer core. Both water ice and sulfur have been postulated as major constituents of the high-radar-backscatter polar deposits. MESSENGER will combine gamma-ray and neutron spectrometry of the surface with ultraviolet spectrometry and in situ particle measurements to detect both neutral and charged species originating from the surface. Such measurements will address the

  18. Mercury's Core Molten, Radar Study Shows

    NASA Astrophysics Data System (ADS)

    2007-05-01

    Scientists using a high-precision planetary radar technique for the first time have discovered that the innermost planet Mercury probably has a molten core, resolving a mystery of more than three decades. The discovery, which used the National Science Foundation's Robert C. Byrd Green Bank Telescope in West Virginia and Arecibo Observatory in Puerto Rico, and NASA/Jet Propulsion Laboratory antennas in California, is an important step toward a better understanding of how planets form and evolve. Planetary Radar High-precision planetary radar technique sent signal to Mercury, received reflection. CREDIT: Bill Saxton, NRAO/AUI/NSF Click on image for high-resolution file (447 KB) "For a long time it was thought we'd have to land spacecraft on Mercury to learn if its core is solid or molten. Now we've answered that question using ground-based telescopes," said Jean-Luc Margot, of Cornell University, leader of the research team, which published its results in the May 4 issue of the journal Science. Mercury is one of the least-understood of the planets in our Solar System. Its distance from the Sun is just over one-third that of the Earth, and it contains a mass just 5½ percent that of Earth. Only about half of Mercury's surface has been photographed by a spacecraft, Mariner 10, back in 1974. Mariner 10 also discovered that Mercury has a weak magnetic field, about one percent as strong as Earth's. That discovery spurred a scientific debate about the planet's core. Scientists normally expect a rocky planet's magnetic field to be caused by an electromagnetic dynamo in a molten core. However, Mercury is so small that most scientists expected its core to have cooled and solidified long ago. Those scientists speculated that the magnetic field seen today may have been "frozen" into the planet when the core cooled. "Whether the core is molten or solid today depends greatly on the chemical composition of the core. That chemical composition can provide important clues about the

  19. The X-Ray Spectrometer for Mercury MESSENGER

    NASA Technical Reports Server (NTRS)

    Starr, R. D.; Ho, G. C.; Schlemm, C.; Gold, R. E.; Goldsten, J. O.; Boynton, W. V.; Trombka, J. I.

    2001-01-01

    Mercury is the closest planet to the Sun and because it is so close, it is difficult to study from Earth-based observatories. Its proximity to the Sun has also limited the number of spacecraft to visit this tiny planet to just one, Mariner 10, which flew by Mercury twice in 1974 and once in 1975. Mariner 10 provided a wealth of new information about Mercury, yet much still remains unknown about Mercury's geologic history and the processes that led to its formation. The origin of Mercury's metal-rich composition is just one area of investigation awaiting more and improved data to sort between competing hypotheses. Mercury plays an important role in comparative planetology, and many of the processes that were important during its formation are relevant to the Earth's early history. MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) is a Discovery mission that has been designed to fly by and orbit Mercury. It will launch in March 2004, flyby Mercury in 2007 and 2008 and enter an elliptical orbit in April 2009. During the one-year orbital phase, a suite of instruments on board the MESSENGER spacecraft will study the exosphere, magnetosphere, surface, and interior of Mercury. One of these instruments will be an X-Ray Spectrometer (XRS) that will measure surface elemental abundances. Remote X-ray spectroscopy has been accomplished before on the Apollo 15 and 16 missions, and more recently on NEAR Shoemaker. The MESSENGER XRS will measure characteristic X-ray emissions induced in the surface of Mercury by the incident solar flux. The Ka lines for the elements Mg, Al, Si, S, Ca, Ti, and Fe will be detected with spatial resolution on the order of 40 km when counting statistics are not a limiting factor. These measurements can be used to obtain quantitative information on elemental composition.

  20. Mapping the Topography of Mercury with MESSENGER Laser Altimetry

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Cavanaugh, John F.; Neumann, Gregory A.; Smith, David E..; Zubor, Maria T.

    2012-01-01

    The Mercury Laser Altimeter onboard MESSENGER involves unique design elements that deal with the challenges of being in orbit around Mercury. The Mercury Laser Altimeter (MLA) is one of seven instruments on NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. MESSENGER was launched on 3 August 2004, and entered into orbit about Mercury on 18 March 2011 after a journey through the inner solar system. This involved six planetary flybys, including three of Mercury. MLA is designed to map the topography and landforms of Mercury's surface. It also measures the planet's forced libration (motion about the spin axis), which helps constrain the state of the core. The first science measurements from orbit taken with MLA were made on 29 March 2011 and continue to date. MLA had accumulated about 8.3 million laser ranging measurements to Mercury's surface, as of 31 July 2012, i.e., over six Mercury years (528 Earth days). Although MLA is the third planetary lidar built at the NASA Goddard Space Flight Center (GSFC), MLA must endure a much harsher thermal environment near Mercury than the previous instruments on Mars and Earth satellites. The design of MLA was derived in part from that of the Mars Orbiter Laser Altimeter on Mars Global Surveyor. However, MLA must range over greater distances and often in off-nadir directions from a highly eccentric orbit. In MLA we use a single-mode diode-pumped Nd:YAG (neodymium-doped yttrium aluminum garnet) laser that is highly collimated to maintain a small footprint on the planet. The receiver has both a narrow field of view and a narrow spectral bandwidth to minimize the amount of background light detected from the sunlit hemisphere of Mercury. We achieve the highest possible receiver sensitivity by employing the minimum receiver detection threshold.

  1. Explaining Mercury's peculiar magnetic field

    NASA Astrophysics Data System (ADS)

    Wicht, Johannes; Cao, Hao; Heyner, Daniel; Dietrich, Wieland; Christensen, Ulrich R.

    2014-05-01

    MESSENGER magnetometer data revealed that Mercury's magnetic field is not only particularly weak but also has a peculiar geometry. The MESSENGER team finds that the location of the magnetic equator always lies significantly north of the geographic equator, is largely independent of the distance to the planet, and also varies only weakly with longitude. The field is best described by an axial dipole that is offset to the north by about 20% of the planetary radius. In terms of classical Gauss coefficients, this translates into a low axial dipole component of g10= -190 nT but a relatively large axial quadrupole contribution that amounts to roughly 40% of this value. The axial octupole is also sizable while higher harmonic contributions are much weaker. Very remarkable is also the fact that the equatorial dipole contribution is very small, consistent with a dipole tilt below 0.8 degree, and this is also true for the other non-axisymmetic field contributions. We analyze several numerical dynamos concerning their capability of explaining Mercury's magnetic field. Classical schemes geared to model the geomagnetic field typically show a much weaker quadrupole component and thus a smaller offset. The onset only becomes larger when the dynamo operates in the multipolar regime at higher Rayleigh numbers. However, since the more complex dynamics generally promotes all higher multipole contributions the location of the magnetic equator varies strongly with longitude and distance to the planet. The situation improves when introducing a stably stratified outer layer in the dynamo region, representing either a rigid FeS layer or a sub-adiabatic core-mantle boundary heat flux. This layer filters out the higher harmonic contributions and the field not only becomes sufficiently weak but also assumes a Mercury like offset geometry during a few percent of the simulation time. To increase the likelihood for the offset configuration, the north-south symmetry must be permanently broken

  2. Large longitude libration of Mercury reveals a molten core.

    PubMed

    Margot, J L; Peale, S J; Jurgens, R F; Slade, M A; Holin, I V

    2007-05-04

    Observations of radar speckle patterns tied to the rotation of Mercury establish that the planet occupies a Cassini state with obliquity of 2.11 +/- 0.1 arc minutes. The measurements show that the planet exhibits librations in longitude that are forced at the 88-day orbital period, as predicted by theory. The large amplitude of the oscillations, 35.8 +/- 2 arc seconds, together with the Mariner 10 determination of the gravitational harmonic coefficient C22, indicates that the mantle of Mercury is decoupled from a core that is at least partially molten.

  3. Space Environment of Mercury at the Time of the First MESSENGER Flyby: Solar Wind and Interplanetary Magnetic Field Modeling of Upstream Conditions

    DTIC Science & Technology

    2009-10-01

    passed over the planet (and MESSENGER) several days prior to the flyby of Mercury with the highest-speed (600 km/s) stream features having been expected...when MESSENGER is in orbit around Mercury , the spacecraft will be within the magnetosphere and magnetotail of the planet for extended portions of...TITLE AND SUBTITLE Space environment of Mercury at the time of the first 3HESSENGER flyby: Solar wind and interplanetary magnetic field •Modeling

  4. Revisiting the Capture of Mercury into Its 3:2 Spin-orbit Resonance

    DTIC Science & Technology

    2014-01-01

    well before differentiation. Keywords. celestial mechanics, planets and satellites: individual ( Mercury ) 1. Previous studies In the literature hitherto...2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Revisiting the capture of Mercury into its 3:2 spin-orbit...Astronomical Union 2014 doi:10.1017/S1743921314007765 Revisiting the capture of Mercury into its 3:2 spin-orbit resonance Benôıt Noyelles1, Julien

  5. Perils of a Restless Planet

    NASA Astrophysics Data System (ADS)

    Zebrowski, Ernest, Jr.

    1999-05-01

    From epidemics and earthquakes to tornados and tidal waves, the overwhelming power of nature never ceases to instill humankind with both terror and awe. As natural disasters continue to claim human lives and leave destruction in their wake, Perils of a Restless Planet examines our attempts to understand and anticipate such phenomena. Now available in paperback, this highly acclaimed book draws on actual events from ancient to present times. Coverage focuses on basic scientific inquiry, technological innovation and, ultimately, public policy to provide a lucid and riveting look at the natural events that have shaped our view of natural disasters. While shedding light on the elusive quality of nature's intermittent tantrums and the limits scientific study and laboratory replication impose on our understanding of its mercurial ways, the author extrapolates from the history of science to suggest how we may someday learn to warn and protect the vulnerable populations on our small, tempestuous planet. Compelling and informative, this book will find readers both in and outside of the scientific community.

  6. Constraining the primordial orbits of the terrestrial planets

    NASA Astrophysics Data System (ADS)

    Brasser, R.; Walsh, K. J.; Nesvorný, D.

    2013-08-01

    late giant planet migration scenario that initially had five giant planets rather than four had a higher probability of satisfying the orbital constraints of the terrestrial planets. Assuming late migration, we predict that Mars was initially on an eccentric and inclined orbit while the orbits of Mercury, Venus and Earth were more circular and coplanar. The lower primordial dynamical excitement and the peculiar partitioning between planets impose new constraints for terrestrial planet formation simulations.

  7. Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

    NASA Technical Reports Server (NTRS)

    Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.; Sarantos, Menelaos

    2014-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variations, but there are no obvious year-to-year variations in most of the observations. We do not see the episodic variability reported by some ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere, at about 1200 K, is much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

  8. Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

    NASA Technical Reports Server (NTRS)

    Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Sarantos, Menelaos; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.

    2014-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variation but there is little or no year-to-year variation; we do not see the episodic variability reported by ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere is about 1200 K, much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

  9. Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

    NASA Technical Reports Server (NTRS)

    Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Sarantos, Menelaos; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.

    2014-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variation but there is little or no year-to-year variation; we do not see the episodic variability reported by ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere is about 1200 K, much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

  10. 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.

  11. Extreme Planets Artist Concept

    NASA Image and Video Library

    2006-04-05

    This artist concept depicts the pulsar planet system discovered by Aleksander Wolszczan in 1992. Wolszczan used the Arecibo radio telescope in Puerto Rico to find three planets circling a pulsar called PSR B1257+12.

  12. Observsational Planet Formation

    NASA Astrophysics Data System (ADS)

    Dong, Ruobing; Zhu, Zhaohuan; Fung, Jeffrey

    2017-06-01

    Planets form in gaseous protoplanetary disks surrounding newborn stars. As such, the most direct way to learn how they form from observations, is to directly watch them forming in disks. In the past, this was very difficult due to a lack of observational capabilities; as such, planet formation was largely a subject of pure theoretical astrophysics. Now, thanks to a fleet of new instruments with unprecedented resolving power that have come online recently, we have just started to unveil features in resolve images of protoplanetary disks, such as gaps and spiral arms, that are most likely associated with embedded (unseen) planets. By comparing observations with theoretical models of planet-disk interactions, the masses and orbits of these still forming planets may be constrained. Such planets may help us to directly test various planet formation models. This marks the onset of a new field — observational planet formation. I will introduce the current status of this field.

  13. Comments on the origin of Mercury

    NASA Technical Reports Server (NTRS)

    Kaula, W. M.

    1976-01-01

    The ratio between the mass of condensed matter in Mercury's nebular zone and the final mass of condensed matter in the planet is calculated, and the result suggests that condensed matter equal to more than 10 times the planet's mass was lost from that zone. Five hypotheses to account for this loss are considered: (1) the temperature in Mercury's zone was appreciably higher than the suggested value of 1400 K, (2) the excess was expelled by solar mass outflow, (3) the excess was dragged down by the sun during its contraction, (4) the excess was knocked out by Jupiter-perturbed planetesimals, and (5) the excess was knocked out by earth- and Venus-perturbed planetesimals. The plausibility of each hypothesis is examined, and it is concluded that only planetesimal scattering by earth and Venus appears to be ruled out

  14. Mercury's Surface: Preliminary Description and Interpretation from Mariner 10 Pictures.

    PubMed

    Murray, B C; Belton, M J; Danielson, G E; Davies, M E; Gault, D E; Hapke, B; O'leary, B; Strom, R G; Suomi, V; Trask, N

    1974-07-12

    The surface morphology and optical properties of Mercury resemble those of the moon in remarkable detail and record a very similar sequence of events. Chemical and mineralogical similarity of the outer layers of Mercury and the moon is implied; Mercury is probably a differentiated planet with a large iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of landforms has been found. Large-scale scarps and ridges unlike lunar or martian features may reflect a unique period of planetary compression near the end of heavy bombardment by small planetesimals.

  15. Mercury's surface: Preliminary description and interpretation from Mariner 10 pictures

    USGS Publications Warehouse

    Murray, B.C.; Belton, M.J.S.; Edward, Danielson G.; Davies, M.E.; Gault, D.E.; Hapke, B.; O'Leary, B.; Strom, R.G.; Suomi, V.; Trask, N.

    1974-01-01

    The surface morphology and optical properties of Mercury resemble those of the moon in remarkable detail and record a very similar sequence of events. Chemical and mineralogical similarity of the outer layers of Mercury and the moon is implied; Mercury is probably a differentiated planet with a large iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of landforms has been found. Large-scale scarps and ridges unlike lunar or martian features may reflect a unique period of planetary compression near the end of heavy bombardment by small planetesimals.

  16. Terrestrial Planets: Comparative Planetology

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Papers were presented at the 47th Annual Meteoritical Society Meeting on the Comparative planetology of Terrestrial Planets. Subject matter explored concerning terrestrial planets includes: interrelationships among planets; plaentary evolution; planetary structure; planetary composition; planetary Atmospheres; noble gases in meteorites; and planetary magnetic fields.

  17. Kepler Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2015-01-01

    Kepler has vastly increased our knowledge of planets and planetary systems located close to stars. The new data shows surprising results for planetary abundances, planetary spacings and the distribution of planets on a mass-radius diagram. The implications of these results for theories of planet formation will be discussed.

  18. Peeking at the Planets.

    ERIC Educational Resources Information Center

    Riddle, Bob

    2002-01-01

    Provides information about each of the planets in our solar system. Focuses on information related to the space missions that have visited or flown near each planet, and includes a summary of what is known about some of the features of each planet. (DDR)

  19. Gravity field and internal structure of Mercury from MESSENGER.

    PubMed

    Smith, David E; Zuber, Maria T; Phillips, Roger J; Solomon, Sean C; Hauck, Steven A; Lemoine, Frank G; Mazarico, Erwan; Neumann, Gregory A; Peale, Stanton J; Margot, Jean-Luc; Johnson, Catherine L; Torrence, Mark H; Perry, Mark E; Rowlands, David D; Goossens, Sander; Head, James W; Taylor, Anthony H

    2012-04-13

    Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR(2) = 0.353 ± 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(m)/C = 0.452 ± 0.035. A model for Mercury's radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core.

  20. Maintaining the Na atmosphere of Mercury

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.; Morgan, Thomas H.

    1993-01-01

    The possible sources of the Na atmosphere of Mercury are calculatively studied. The likely structure, composition, and temperature of the planet's upper crust is examined along with the probable flux of Na from depth by grain boundary diffusion and by Knudsen flow. The creation of fresh regolith is considered along with mechanisms for supplying Na from the surface to the exosphere. The implications of the calculations for the probable abundances in the regolith are discussed.

  1. Maintaining the NA atmosphere of Mercury

    NASA Astrophysics Data System (ADS)

    Killen, R. M.; Morgan, T. H.

    1993-02-01

    The possible sources of the Na atmosphere of Mercury are calculatively studied. The likely structure, composition, and temperature of the planet's upper crust is examined along with the probable flux of Na from depth by grain boundary diffusion and by Knudsen flow. The creation of fresh regolith is considered along with mechanisms for supplying Na from the surface to the exosphere. The implications of the calculations for the probable abundances in the regolith are discussed.

  2. Distribution, Statistics, and Resurfacing of Large Impact Basins on Mercury

    NASA Technical Reports Server (NTRS)

    Fassett, Caleb I.; Head, James W.; Baker, David M. H.; Chapman, Clark R.; Murchie, Scott L.; Neumann, Gregory A.; Oberst, Juergen; Prockter, Louise M.; Smith, David E.; Solomon, Sean C.; Strom, Robert G.; Xiao, Zhiyong; Zuber, Maria T.

    2012-01-01

    The distribution and geological history of large impact basins (diameter D greater than or equal to 300 km) on Mercury is important to understanding the planet's stratigraphy and surface evolution. It is also informative to compare the density of impact basins on Mercury with that of the Moon to understand similarities and differences in their impact crater and basin populations [1, 2]. A variety of impact basins were proposed on the basis of geological mapping with Mariner 10 data [e.g. 3]. This basin population can now be re-assessed and extended to the full planet, using data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Note that small-to- medium-sized peak-ring basins on Mercury are being examined separately [4, 5]; only the three largest peak-ring basins on Mercury overlap with the size range we consider here. In this study, we (1) re-examine the large basins suggested on the basis of Mariner 10 data, (2) suggest additional basins from MESSENGER's global coverage of Mercury, (3) assess the size-frequency distribution of mercurian basins on the basis of these global observations and compare it to the Moon, and (4) analyze the implications of these observations for the modification history of basins on Mercury.

  3. Scientific objectives and instrumentation of Mercury Plasma Particle Experiment (MPPE) onboard MMO

    NASA Astrophysics Data System (ADS)

    Saito, Y.; Sauvaud, J. A.; Hirahara, M.; Barabash, S.; Delcourt, D.; Takashima, T.; Asamura, K.; BepiColombo MMO/MPPE Team

    2010-01-01

    Mercury is one of the least explored planets in our solar system. Until the recent flyby of Mercury by MESSENGER, no spacecraft had visited Mercury since Mariner 10 made three flybys: two in 1974 and one in 1975. In order to elucidate the detailed plasma structure and dynamics around Mercury, an orbiter BepiColombo MMO (Mercury Magnetospheric Orbiter) is planned to be launched in 2013 as a joint mission between ESA and ISAS/JAXA. Mercury Plasma Particle Experiment (MPPE) was proposed in order to investigate the plasma/particle environment around Mercury. MPPE is a comprehensive instrument package for plasma, high-energy particle and energetic neutral atom measurements. It consists of seven sensors: two Mercury electron analyzers (MEA1 and MEA2), Mercury ion analyzer (MIA), Mercury mass spectrum analyzer (MSA), high-energy particle instrument for electron (HEP-ele), high-energy particle instrument for ion (HEP-ion), and energetic neutrals analyzer (ENA). Since comprehensive full three-dimensional simultaneous measurements of low to high-energy ions and electrons around Mercury as well as measurements of energetic neutral atoms will not be realized before BepiColombo/MMO's arrival at Mercury, it is expected that many unresolved problems concerning the Mercury magnetosphere will be elucidated by the MPPE observation.

  4. Substorm Current Wedge at Earth and Mercury

    NASA Astrophysics Data System (ADS)

    Kepko, L.; Glassmeier, K.-H.; Slavin, J. A.; Sundberg, T.

    2015-01-01

    This chapter reviews magnetospheric substorms and dipolarizations observed at both Earth and Mercury. It briefly discusses new insights into the physics of the substorm current wedge (SCW) that have been revealed the past few years. The formation and evolution of the SCW are closely tied to the braking of flows convecting flux away from the reconnection site and the resultant near-planet flux pileup that creates the dipolarization. At Earth, the SCW plays a critical role in substorms, coupling magnetospheric to ionospheric motions, deflecting incoming plasma flows, and regulating the dissipation of pressure built up in the near-Earth magnetosphere during dipolarization. The lack of a conducting boundary at Mercury provides a natural experiment to examine the role of an ionosphere on regulating magnetospheric convection. Energetic particles may play a much greater role within substorms at Mercury than at Earth, providing another opportunity for comparative studies.

  5. Energetic neutral atom imaging at Mercury

    NASA Astrophysics Data System (ADS)

    Barabash, S.; Holmström, M.

    In magnetospheric research, Energetic Neutral Atoms (ENA) are atoms with energy much greater than the escape energy at the planet in question. They propagate unaffected by gravitational and electromagnetic forces and can be used to image the regions of generation. ENAs at planets are produced by (1) charge-exchang of energetic ions in the near-planet environment with the planetary exosphere and (2) by sputtering of, or backscattering from, the planetary surface and atmosphere. Mercury has a tenuous exosphere, but yet it is sufficiently dense to convert ions of solar wind and planetary origin into ENAs. The ENA fluxes reach 102 - 103 (cm2 sr s keV)-1 and up to 104 - 105 (cm2 sr s keV)-1 in the energy range 10-50 keV. That is very similar to the Earth's ring current conditions. What is unique for Mercury is the high variability of the Mercury magnetosphere giving rise to pulsating ENA emissions (ENA "flashes") with a period of a minute. Due to the small size of the magnetosphere, the particles injected from the tail can fill up the entire dayside magnetosphere, making possible ENA imaging of the magnetosphere shape. Both the ions coming directly from the solar wind and those accelerated in the tail, as well as energized planetary ions, precipitate on the Mercury surface resulting in extensive sputtering. The integrated energy spectrum of the sputtered products falls off as E -2 (the Thompson-Siegmund formula) and results in high fluxes at energies greater than 10-100 eV. For example, the direct impact of the solar wind on the surface results in ENA fluxes of 105 - 107 (cm2 sr s)-1 for E > 100eV . ENAs originated from sputtering can be used to visualize the precipitation regions in a similar way as the terrestrial aurora displays magnetospheric dynamics (ENA "aurora" at Mercury). Moreover, measurements of these ENAs are crucial for understanding the contribution of sputtering to the formation of the Mercury exosphere. Surface sputtering at Mercury resembles in some

  6. Extrasolar planets: constraints for planet formation models.

    PubMed

    Santos, Nuno C; Benz, Willy; Mayor, Michel

    2005-10-14

    Since 1995, more than 150 extrasolar planets have been discovered, most of them in orbits quite different from those of the giant planets in our own solar system. The number of discovered extrasolar planets demonstrates that planetary systems are common but also that they may possess a large variety of properties. As the number of detections grows, statistical studies of the properties of exoplanets and their host stars can be conducted to unravel some of the key physical and chemical processes leading to the formation of planetary systems.

  7. The Trojan minor planets

    NASA Astrophysics Data System (ADS)

    Spratt, Christopher E.

    1988-08-01

    There are (March, 1988) 3774 minor planets which have received a permanent number. Of these, there are some whose mean distance to the sun is very nearly equal to that of Jupiter, and whose heliocentric longitudes from that planet are about 60°, so that the three bodies concerned (sun, Jupiter, minor planet) make an approximate equilateral triangle. These minor planets, which occur in two distinct groups, one preceding Jupiter and one following, have received the names of the heroes of the Trojan war. This paper concerns the 49 numbered minor planets of this group.

  8. Mercury's global evolution: New views from MESSENGER

    NASA Astrophysics Data System (ADS)

    Hauck, S. A., II; Byrne, P. K.; Denevi, B. W.; Grott, M.; McCoy, T.; Stanley, S.

    2015-12-01

    MESSENGER's exploration of Mercury has revealed the planet's rich and dynamic history and provided new constraints on the processes that control its internal evolution. Mercury's surface records evidence of an extensive geological history. This evidence includes resurfacing by impacts and volcanism prior to the end of the late heavy bombardment (LHB) and a subsequent rapid waning of effusive volcanism. Volcanism is an important indicator of the history of melt production. Thousands of globally distributed, contractional tectonic landforms collectively have accommodated a decrease in Mercury's radius of 5-7 km since the end of the LHB. Such contraction results from planetary cooling and crystallization within Mercury's metallic core. Measurements of surface chemistry have provided constraints on internal radiogenic heat production necessary to understand more fully Mercury's thermal evolution. Elemental abundances also reveal that Mercury is strongly chemically reduced, suggesting that the core's iron is alloyed with silicon as well as sulfur, which constrains the dynamics and crystallization of the metallic core. Magnetometer observations show that Mercury's dynamo-generated, dominantly dipolar field is displaced ~500 km northward along the rotation axis. Low-altitude magnetic field observations late in the mission led to the discovery of crustal magnetization in Mercury's ancient crust, dating to at least 3.7 Ga, which places a new constraint on the timing of the dynamo. Monte Carlo parameterized mantle convection models, constrained by these observations, indicate that for global contraction of 7 km or less, mantle convection persists to the present ~40% of the time, with the likelihood of modern convection decreasing with less global contraction. Slow present cooling in these models indicates that dynamo generation is strongly influenced by both a static layer at the top of the core and convective motions within the core driven by compositional buoyancy.

  9. Mission provides new findings about Mercury

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-06-01

    Mercury once was considered by even some planetary scientists as “an example, to use a phrase coined by a very famous scientist, as ‘one of the burnt-out cinders of the solar system.’ And it is anything but that,” Sean Solomon, who is principal investigator of NASA's Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft, said at a 16 June briefing at NASA headquarters in Washington, D. C. Scientists at the briefing announced significant new findings about the planet's chemical composition, topography, magnetic field, and other features. MESSENGER has now logged more than 1 Mercurian year (about 88 Earth days) as the first satellite in orbit around the closest planet to the Sun, and new understandings are being gleaned from the spacecraft's imaging system, which has already taken more than 20,000 images of Mercury. In addition, the laser altimeter has operated more than 2 million times from orbit thus far, and other instruments are also gathering extensive data about the planet.

  10. Mercury contamination extraction

    DOEpatents

    Fuhrmann, Mark [Silver Spring, MD; Heiser, John [Bayport, NY; Kalb, Paul [Wading River, NY

    2009-09-15

    Mercury is removed from contaminated waste by firstly applying a sulfur reagent to the waste. Mercury in the waste is then permitted to migrate to the reagent and is stabilized in a mercury sulfide compound. The stable compound may then be removed from the waste which itself remains in situ following mercury removal therefrom.

  11. MERCURY RESEARCH STRATEGY.

    EPA Science Inventory

    The USEPA's ORD is pleased to announce the availability of its Mercury Research Strategy. This strategy guides ORD's mercury research program and covers the FY2001-2005 time frame. ORD will use it to prepare a multi-year mercury research implementation plan in 2001. The Mercury R...

  12. MERCURY RESEARCH STRATEGY.

    EPA Science Inventory

    The USEPA's ORD is pleased to announce the availability of its Mercury Research Strategy. This strategy guides ORD's mercury research program and covers the FY2001-2005 time frame. ORD will use it to prepare a multi-year mercury research implementation plan in 2001. The Mercury R...

  13. Planet Demographics from Transits

    NASA Astrophysics Data System (ADS)

    Howard, Andrew

    2015-08-01

    From the demographics of planets detected by the Kepler mission, we have learned that there exists approximately one planet per star for planets larger than Earth orbiting inside of 1 AU. We have also learned the relative occurrence of these planets as a function of their orbital periods, sizes, and host star masses and metallicities. In this talk I will review the key statistical findings that the planet size distribution peaks in the range 1-3 times Earth-size, the orbital period distribution is characterized by a power-law cut off at short periods, small planets are more prevalent around small stars, and that approximately 20% of Sun-like stars hosts a planet 1-2 times Earth-size in a habitable zone. Looking forward, I will describe analysis of photometry from the K2 mission that is yielding initial planet discoveries and offering the opportunity to measure planet occurrence in widely separated regions of the galaxy. Finally, I will also discuss recent techniques to discover transiting planets in space-based photometry and to infer planet population properties from the ensemble of detected and non-detected transit signals.

  14. THEORY OF SECULAR CHAOS AND MERCURY'S ORBIT

    SciTech Connect

    Lithwick, Yoram; Wu Yanqin

    2011-09-20

    We study the chaotic orbital evolution of planetary systems, focusing on secular (i.e., orbit-averaged) interactions, which dominate on long timescales. We first focus on the evolution of a test particle that is forced by multiple planets. To linear order in eccentricity and inclination, its orbit precesses with constant frequencies. But nonlinearities modify the frequencies, and can shift them into and out of resonance with either the planets' eigenfrequencies (forming eccentricity or inclination secular resonances), or with linear combinations of those frequencies (forming mixed high-order secular resonances). The overlap of these nonlinear secular resonances drives secular chaos. We calculate the locations and widths of nonlinear secular resonances, display them together on a newly developed map (the 'map of the mean momenta'), and find good agreement between analytical and numerical results. This map also graphically demonstrates how chaos emerges from overlapping secular resonances. We then apply this newfound understanding to Mercury to elucidate the origin of its orbital chaos. We find that since Mercury's two free precession frequencies (in eccentricity and inclination) lie within {approx}25% of two other eigenfrequencies in the solar system (those of the Jupiter-dominated eccentricity mode and the Venus-dominated inclination mode), secular resonances involving these four modes overlap and cause Mercury's chaos. We confirm this with N-body integrations by showing that a slew of these resonant angles alternately librate and circulate. Our new analytical understanding allows us to calculate the criterion for Mercury to become chaotic: Jupiter and Venus must have eccentricity and inclination of a few percent. The timescale for Mercury's chaotic diffusion depends sensitively on the forcing. As it is, Mercury appears to be perched on the threshold for chaos, with an instability timescale comparable to the lifetime of the solar system.

  15. The geology of the terrestrial planets.

    USGS Publications Warehouse

    Carr, M.H.

    1983-01-01

    During the last four years our knowledge of the geology of the terrestrial planets has advanced rapidly. The advances are particularly noticeable for Venus and Mars. Improved understanding of Venus has come largely from the Pioneer Venus mission. The period was also one of almost continuous data gathering for Mars as the Viking orbiters and landers, emplaced at the planet in 1976, continued to function. The last orbiter ran out of attitude- control gas in August of 1980 by which time about 55 000 pictures and vast amounts of infrared data had been collected. One lander continues to function and is expected to do so for several years. Only modest advances were made in the cases of Moon and Mercury, however, for little new data was acquired. -from Author

  16. Plasma Transport, Acceleration, and Loss in Mercury's Magnetosphere and Comparison with Other Planetary Magnetospheres

    NASA Astrophysics Data System (ADS)

    Schriver, D.; Travnicek, P. M.; Anderson, B. J.; Ashour-Abdalla, M.; Baker, D. N.; Benna, M.; Boardsen, S. A.; Hellinger, P.; Ho, G. C.; Korth, H.; Krimigis, S. M.; McNutt, R. L., Jr.; Raines, J. M.; Richard, R. L.; Slavin, J. A.; Starr, R. D.; Solomon, S. C.; Zurbuchen, T.

    2014-12-01

    Mercury has the distinction of having the smallest planetary magnetosphere in the solar system, in contrast to the mid-sized magnetosphere of Earth and the very large magnetospheres of the outer planets. Observations by the MESSENGER spacecraft in orbit around Mercury have established that Mercury's magnetosphere has a global structure similar to those found in the other planetary magnetospheres, i.e., a foreshock, bow shock, magnetosheath, magnetopause, cusps, and magnetotail. There are also auroral signatures observed at Mercury associated with the precipitation of electrons; those signatures are not in the visible range, however, but rather appear as nightside X-ray fluorescence. Heavy ions (primarily Na+) from the planet surface mass load Mercury's magnetosphere in a manner analogous to the internal sources of heavy ions in the other planetary magnetospheres, e.g., Earth's ionosphere and moons of the outer planets. One feature not found at Mercury compared with the other planetary magnetospheres is the presence of a high-energy (> hundreds of keV) trapped radiation belt region. Although there are observations of high energy electron bursts within Mercury's magnetosphere, these are not stably trapped and instead Mercury has a quasi-trapped population of ions and electrons with 1-10 keV bulk energies at about 1.5 RM (RM is Mercury's radius = 2440 km) radial distance from the planet center. MESSENGER spacecraft observations and results from a global kinetic simulation model of the solar wind interaction with Mercury's magnetosphere provide a basis for describing the transport, acceleration, and loss of plasma, those features and processes unique to Mercury, as well as those in common with other planetary magnetospheres in the solar system.

  17. Mercury and health care

    PubMed Central

    Rustagi, Neeti; Singh, Ritesh

    2010-01-01

    Mercury is toxic heavy metal. It has many characteristic features. Health care organizations have used mercury in many forms since time immemorial. The main uses of mercury are in dental amalgam, sphygmomanometers, and thermometers. The mercury once released into the environment can remain for a longer period. Both acute and chronic poisoning can be caused by it. Half of the mercury found in the atmosphere is human generated and health care contributes the substantial part to it. The world has awakened to the harmful effects of mercury. The World Health Organization and United Nations Environmental Programme (UNEP) have issued guidelines for the countries’ health care sector to become mercury free. UNEP has formed mercury partnerships between governments and other stakeholders as one approach to reducing risks to human health and the environment from the release of mercury and its compounds to the environment. Many hospitals are mercury free now. PMID:21120080

  18. Mercury's Dynamic Magnetosphere: What Have We Learned from MESSENGER?

    NASA Astrophysics Data System (ADS)

    Slavin, James A.

    2016-04-01

    Mercury's magnetosphere is created by the solar wind interaction with its dipolar, spin-axis aligned, northward offset intrinsic magnetic field. Structurally it resembles that of the Earth in many respects, but the magnetic field intensities and plasma densities are all higher at Mercury due to conditions in the inner solar system. Magnetospheric plasma at Mercury appears to be primarily of solar wind origin, i.e. H+ and He++, but with 10% Na+ derived from the exosphere. Solar wind sputtering and other processes promote neutrals from the regolith into the exosphere where they may be ionized and incorporated into the magnetospheric plasma population. At this point in time, about one year after MESSENGER's impact and one year prior to BepiColombo's launch, we review MESSENGER's observations of magnetospheric dynamics and structure. In doing so we will provide our best answers to the following six questions: Question #1: How do magnetosheath conditions at Mercury differ from what is found at the other planets? Question #2: How do conditions in Mercury's magnetosheath contribute to the dynamic nature of Mercury's magnetosphere? How does magnetopause reconnection at Mercury differ from what is seen at Earth? Are flux transfer events (FTEs) a major driver of magnetospheric convection at Mercury? Question #3: Does reconnection ever erode the dayside magnetosphere to the point where the subsolar region of the surface is exposed to direct solar wind impact? To what extent do induction currents driven in Mercury's interior limit the solar wind flux to the surface? Do FTEs contribute significantly to the solar wind flux reaching the surface? Question #4: What effects do heavy planetary ions have on Mercury's magnetosphere? Question #5: Does Mercury's magnetotail store and dissipate magnetic energy in a manner analogous to substorms at Earth? How is the process affected by the lack of an ionosphere and the expected high electrical resistivity of the crust? Question #6: How

  19. Erosion and Sublimation Effects On Mercury`s Surface: Past and Present

    NASA Astrophysics Data System (ADS)

    Tehrany, M. G.; Lammer, H.; Hanslmeier, A.; Ribas, I.; Guinan, E. F.; Kolb, C.

    Ground-based observations of heavy constituents like Na, K and O in Mercury`s present exosphere indicate a strong exosphere-surface interaction related to the par- ticle and radiation environment of the close Sun. Recent studies of isotope anomalies in planetary atmospheres and meteorites suggest that our early Sun underwent a highly active phase after its origin that included continuous flare events and had a particle and radiation environment several hundred times stronger than today. Since Mercury is the closest planet to the Sun, its surface was more heavily exposed to the enhanced solar wind particle and radiation fluxes than those of any of the other Solar System bod- ies. To evaluate how such effects may have influenced Mercury`s surface, we study its surface erosion and sublimation during the planet history by using solar analogue G-type stars. The astrophysical parameters of these Sun-like stars were studied within the broader "Sun in Time" program. We use for our study three models for the young Sun: one model with an initial solar mass of 2, where the mass loss rate and luminos- ity decreases exponentially with e-folding times of a few 10E8 years; a second model, which can be compared to solar analogue observations, including large flare events during the first hundred million years; and a third model, which is the standard model. The results of the analysis of these three models are used to estimate and compare the sputter erosion and sublimation rates of Mercury`s surface during its history.

  20. Exploring the planets with spacecraft - Accomplishments to date

    NASA Technical Reports Server (NTRS)

    Rea, D. G.

    1974-01-01

    A summary of knowledge gained about Venus, Mars, Jupiter, and Mercury via spacecraft. Mariner and Venera probes returned data on Venus' size, atmospheric structure and composition, temperature profiles, and magnetic field. Knowledge of the clouds is still primitive. Mars and Mariner probes (especially Mariner 9) expanded knowledge of the Martian surface, atmospheric structure and dynamics, and magnetic field. Mars is now viewed as a very active planet, with the possibility of life not immediately ruled out. Pioneer 10 returned data on Jovian temperature profiles and magnetic field, Galilean satellite masses, and Io's atmosphere. Mariner 10 added to knowledge of Mercury's surface, magnetic field, atmosphere, and activity.

  1. Exploring the planets with spacecraft - Accomplishments to date

    NASA Technical Reports Server (NTRS)

    Rea, D. G.

    1974-01-01

    A summary of knowledge gained about Venus, Mars, Jupiter, and Mercury via spacecraft. Mariner and Venera probes returned data on Venus' size, atmospheric structure and composition, temperature profiles, and magnetic field. Knowledge of the clouds is still primitive. Mars and Mariner probes (especially Mariner 9) expanded knowledge of the Martian surface, atmospheric structure and dynamics, and magnetic field. Mars is now viewed as a very active planet, with the possibility of life not immediately ruled out. Pioneer 10 returned data on Jovian temperature profiles and magnetic field, Galilean satellite masses, and Io's atmosphere. Mariner 10 added to knowledge of Mercury's surface, magnetic field, atmosphere, and activity.

  2. Exploration of terrestrial planets from spacecraft: instrumentation, investigation, interpretation.

    NASA Astrophysics Data System (ADS)

    Surkov, Yu. A.

    This book is an English translation of the Russian original "Kosmokhimicheskie issledovaniia planet i sputnikov" published in 1985. It describes the methods, instrumentation and experimental results which have already been used or which will be used by space vehicles for exploring the composition, structure and properties of extraterrestrial material, on the basis of which modern concepts of the planets and planetary satellites have been developed. Contents: Part I. Modern concepts of planets and satellites. 1. Origin and evolution of the solar system. 2. Mercury. 3. Venus. 4. Mars. 5. Planetary satellites. Part II. Exploration of planets and satellites by space vehicles. 1. Gamma-ray spectrometric studies. 2. X-ray spectrometric studies. 3. Neutronmetry. 4. Alpha-spectrometry. 5. Mass-spectrometric studies. 6. The exploration of Mars and Phobos (Phobos mission). 7. First results of gamma-ray measurements of Mars from Phobos 2 spacecraft.

  3. FORMATION OF THE TERRESTRIAL PLANETS FROM A NARROW ANNULUS

    SciTech Connect

    Hansen, Brad M. S.

    2009-09-20

    We show that the assembly of the solar system terrestrial planets can be successfully modeled with all of the mass initially confined to a narrow annulus between 0.7 and 1.0 AU. With this configuration, analogs of Mercury and Mars often form from the collisional evolution of material diffusing out of the annulus under the scattering of the forming Earth and Venus analogs. The final systems also possess eccentricities and inclinations that match the observations, without recourse to dynamical friction from remnant small body populations. Finally, the characteristic assembly timescale for Earth analogs is rapid in this model and consistent with cosmochemical models based on the {sup 182}Hf-{sup 182}W isotopes. The agreement between this model and the observations suggests that terrestrial planet systems may also be formed in 'planet traps', as has been proposed recently for the cores of giant planets in our solar system and others.

  4. On the mechanism of the magnetic dynamo of the planets

    NASA Technical Reports Server (NTRS)

    Dolginov, S. S.

    1977-01-01

    Results of testing the effectiveness of the theory of precessional dynamos in the generation of the magnetic fields of the planets are presented. It is shown that the magnetic state of Earth and of the planets Mars, Jupiter, and Venus can be satisfactorily described by the formula H(i) = H(3) V(i)/V(3) T(3)/T(i) omega(i)/omega(3) sin(alpha 1)/sin(alpha 2) where H, V, T, omega and alpha are the dipole fields, volumes of liquid cores, periods of rotation, rates of precession, and angles between precession vector and angular rotation, respectively, for the planets and earth. The v(i) corresponds to known models of the internal structure. It is shown that the magnetic state of Mercury satisfies this formula if the dynamic flattening of the planet f = .000057-.000083.

  5. Widespread effusive volcanism on Mercury likely ended by about 3.5 Ga

    NASA Astrophysics Data System (ADS)

    Byrne, Paul K.; Ostrach, Lillian R.; Fassett, Caleb I.; Chapman, Clark R.; Denevi, Brett W.; Evans, Alexander J.; Klimczak, Christian; Banks, Maria E.; Head, James W.; Solomon, Sean C.

    2016-07-01

    Crater size-frequency analyses have shown that the largest volcanic plains deposits on Mercury were emplaced around 3.7 Ga, as determined with recent model production function chronologies for impact crater formation on that planet. To test the hypothesis that all major smooth plains on Mercury were emplaced by about that time, we determined crater size-frequency distributions for the nine next-largest deposits, which we interpret also as volcanic. Our crater density measurements are consistent with those of the largest areas of smooth plains on the planet. Model ages based on recent crater production rate estimates for Mercury imply that the main phase of plains volcanism on Mercury had ended by ~3.5 Ga, with only small-scale volcanism enduring beyond that time. Cessation of widespread effusive volcanism is attributable to interior cooling and contraction of the innermost planet.

  6. Wave of a Planet

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This plot tells astronomers that a fifth planet is in orbit around the star 55 Cancri, making the star the record-holder for hosting the most known exoplanets.

    As planets circle around their stars, they cause the stars to wobble back and forth in a regular pattern. By looking for this motion in a star, scientists can find planets that can't be seen with telescopes.

    The wobble caused by the fifth planet discovered around 55 Cancri is represented here by the sinuous line in blue. The actual data points are yellow and error bars are the lines above and below the yellow dots. The cycle of the wobble indicates that the planet circles around its star about every 260 days. The amplitude of the wobble indicates that the planet is a giant at least 45 times the mass of Earth.

    The wobbles caused by the other four planets has been removed from this plot, to reveal that caused by the fifth. The departure from a perfect sine wave suggests the planet's orbit is not perfectly circular.

    Because 55 Cancri has multiple planets, the star had to be observed for a long time before astronomers could find and confirm its fifth planet. These data were collected over a period of 18 years using both the Lick Observatory near San Jose, Calif., and the W.M. Keck Observatory in Hawaii.

  7. Energetic Particles Dynamics in Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Ryou, A.S.; Sibeck, D. G.; Alexeev, I. I.

    2013-01-01

    We investigate the drift paths of energetic particles in Mercury's magnetosphere by tracing their motion through a model magnetic field. Test particle simulations solving the full Lorentz force show a quasi-trapped energetic particle population that gradient and curvature drift around the planet via "Shabansky" orbits, passing though high latitudes in the compressed dayside by equatorial latitudes on the nightside. Due to their large gyroradii, energetic H+ and Na+ ions will typically collide with the planet or the magnetopause and will not be able to complete a full drift orbit. These simulations provide direct comparison for recent spacecraft measurements from MESSENGER. Mercury's offset dipole results in an asymmetric loss cone and therefore an asymmetry in particle precipitation with more particles precipitating in the southern hemisphere. Since the planet lacks an atmosphere, precipitating particles will collide directly with the surface of the planet. The incident charged particles can kick up neutrals from the surface and have implications for the formation of the exosphere and weathering of the surface

  8. Near Global Mosaic of Mercury

    NASA Astrophysics Data System (ADS)

    Becker, K. J.; Robinson, M. S.; Becker, T. L.; Weller, L. A.; Turner, S.; Nguyen, L.; Selby, C.; Denevi, B. W.; Murchie, S. L.; McNutt, R. L.; Solomon, S. C.

    2009-12-01

    In 2008 the MESSENGER spacecraft made two close flybys (M1 and M2) of Mercury and imaged about 74% of the planet at a resolution of 1 km per pixel, and at higher resolution for smaller portions of the planet. The Mariner 10 spacecraft imaged about 42% of Mercury’s surface more than 30 years ago. Combining image data collected by the two missions yields coverage of about 83% of Mercury’s surface. MESSENGER will perform its third and final flyby of Mercury (M3) on 29 September 2009. This will yield approximately 86% coverage of Mercury, leaving only the north and south polar regions yet to be imaged by MESSENGER after orbit insertion in March 2011. A new global mosaic of Mercury was constructed using 325 images containing 3566 control points (8110 measures) from M1 and 225 images containing 1465 control points (3506 measures) from M2. The M3 flyby is shifted in subsolar longitude only by 4° from M2, so the added coverage is very small. However, this small slice of Mercury fills a gore in the mosaic between the M1 and M2 data and allows a complete cartographic tie around the equator. We will run a new bundle block adjustment with the additional images acquired from M3. This new edition of the MESSENGER Mercury Dual Imaging System (MDIS) Narrow Angle Camera (NAC) global mosaic of Mercury includes many improvements since the M2 flyby in October 2008. A new distortion model for the NAC camera greatly improves the image-to-image registration. Optical distortion correction is independent of pointing error correction, and both are required for a mosaic of high quality. The new distortion model alone reduced residual pointing errors for both flybys significantly; residual pixel error improved from 0.71 average (3.7 max) to 0.13 average (1.7 max) for M1 and from 0.72 average (4.8 max.) to 0.17 average (3.5 max) for M2. Analysis quantifying pivot motor position has led to development of a new model that improves accuracy of the pivot platform attitude. This model improves

  9. Interaction of solar wind with Mercury and its magnetic field. [as observed by Mariner 10 space probe

    NASA Technical Reports Server (NTRS)

    Ness, N. F.; Behannon, K. W.; Lepping, R. P.; Whang, Y. C.

    1976-01-01

    A brief review is presented of magnetic field and solar wind electron observations by Mariner 10 spacecraft. The intrinsic magnetic field of the planet Mercury and the implications of such a field for the planetary interior are also discussed.

  10. Basin-Forming Impact Events on Mercury: Effects on Melt Production and Depth of the Source Region

    NASA Astrophysics Data System (ADS)

    Padovan, S.; Tosi, N.; Plesa, A.-C.

    2016-08-01

    In this work we investigate to which degree large impact events on Mercury can modify the underlying mantle dynamics and how the presence of post-impact volcanism or lack thereof can be related to the planet's interior properties.

  11. Compact, passively Q-switched Nd:YAG laser for the MESSENGER mission to Mercury.

    PubMed

    Krebs, Danny J; Novo-Gradac, Anne-Marie; Li, Steven X; Lindauer, Steven J; Afzal, Robert S; Yu, Anthony W

    2005-03-20

    A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter, an instrument on the Mercury Surface, Space Environment, Geochemistry, and Ranging mission to the planet Mercury. The laser achieves 5.4% efficiency with a near-diffraction-limited beam. It passed all space-flight environmental tests at subsystem, instrument, and satellite integration testing and successfully completes a postlaunch aliveness check en route to Mercury. The laser design draws on a heritage of previous laser altimetry missions, specifically the Ice Cloud and Elevation Satellite and the Mars Global Surveyor, but incorporates thermal management features unique to the requirements of an orbit of the planet Mercury.

  12. MESSENGER at Mercury: Early Orbital Operations

    NASA Technical Reports Server (NTRS)

    McNutt, Ralph L., Jr.; Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Krimigis, Stamatios M.; Murchie, Scott L.; Nittler, Larry R.; Slavin, James A.

    2012-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 under NASA's Discovery Program, was inserted into orbit about the planet Mercury in March 2011. MESSENGER's three flybys of Mercury in 2008-2009 marked the first spacecraft visits to the innermost planet since the Mariner 10 flybys in 1974-1975. The unprecedented orbital operations are yielding new insights into the nature and evolution of Mercury. The scientific questions that frame the MESSENGER mission led to the mission measurement objectives to be achieved by the seven payload instruments and the radio science experiment. Interweaving the full set of required orbital observations in a manner that maximizes the opportunity to satisfy all mission objectives and yet meet stringent spacecraft pointing and thermal constraints was a complex optimization problem that was solved with a software tool that simulates science observations and tracks progress toward meeting each objective. The final orbital observation plan, the outcome of that optimization process, meets all mission objectives. MESSENGER's Mercury Dual Imaging System is acquiring a global monochromatic image mosaic at better than 90%coverage and at least 250 m average resolution, a global color image mosaic at better than 90%coverage and at least 1 km average resolution, and global stereo imaging at better than 80%coverage and at least 250 m average resolution. Higher-resolution images are also being acquired of targeted areas. The elemental remote sensing instruments, including the Gamma-Ray and Neutron Spectrometer and the X-Ray Spectrometer, are being operated nearly continuously and will establish the average surface abundances of most major elements. The Visible and Infrared Spectrograph channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer is acquiring a global map of spectral reflectance from 300 to 1450 nm wavelength at a range of incidence and emission angles

  13. MESSENGER at Mercury: Early orbital operations

    NASA Astrophysics Data System (ADS)

    McNutt, Ralph L.; Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Krimigis, Stamatios M.; Murchie, Scott L.; Nittler, Larry R.; Phillips, Roger J.; Prockter, Louise M.; Slavin, James A.; Zuber, Maria T.; Finnegan, Eric J.; Grant, David G.; MESSENGER Team

    2014-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 under NASA's Discovery Program, was inserted into orbit about the planet Mercury in March 2011. MESSENGER's three flybys of Mercury in 2008-2009 marked the first spacecraft visits to the innermost planet since the Mariner 10 flybys in 1974-1975. The unprecedented orbital operations are yielding new insights into the nature and evolution of Mercury. The scientific questions that frame the MESSENGER mission led to the mission measurement objectives to be achieved by the seven payload instruments and the radio science experiment. Interweaving the full set of required orbital observations in a manner that maximizes the opportunity to satisfy all mission objectives and yet meet stringent spacecraft pointing and thermal constraints was a complex optimization problem that was solved with a software tool that simulates science observations and tracks progress toward meeting each objective. The final orbital observation plan, the outcome of that optimization process, meets all mission objectives. MESSENGER's Mercury Dual Imaging System is acquiring a global monochromatic image mosaic at better than 90% coverage and at least 250 m average resolution, a global color image mosaic at better than 90% coverage and at least 1 km average resolution, and global stereo imaging at better than 80% coverage and at least 250 m average resolution. Higher-resolution images are also being acquired of targeted areas. The elemental remote sensing instruments, including the Gamma-Ray and Neutron Spectrometer and the X-Ray Spectrometer, are being operated nearly continuously and will establish the average surface abundances of most major elements. The Visible and Infrared Spectrograph channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer is acquiring a global map of spectral reflectance from 300 to 1450 nm wavelength at a range of incidence and emission

  14. MESSENGER at Mercury: Early Orbital Operations

    NASA Technical Reports Server (NTRS)

    McNutt, Ralph L., Jr; Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Krimigis, Stamatios M.; Murchie, Scott L.; Nittler, Larry R.; hide

    2013-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 under NASA's Discovery Program, was inserted into orbit about the planet Mercury in March 2011. MESSENGER's three flybys of Mercury in 2008-2009 marked the first spacecraft visits to the innermost planet since the Mariner 10 flybys in 1974-1975. The unprecedented orbital operations are yielding new insights into the nature and evolution of Mercury. The scientific questions that frame the MESSENGER mission led to the mission measurement objectives to be achieved by the seven payload instruments and the radio science experiment. Interweaving the full set of required orbital observations in a manner that maximizes the opportunity to satisfy all mission objectives and yet meet stringent spacecraft pointing and thermal constraints was a complex optimization problem that was solved with a software tool that simulates science observations and tracks progress toward meeting each objective. The final orbital observation plan, the outcome of that optimization process, meets all mission objectives. MESSENGER's Mercury Dual Imaging System is acquiring a global monochromatic image mosaic at better than 90% coverage and at least 250 m average resolution, a global color image mosaic at better than 90% coverage and at least 1 km average resolution, and global stereo imaging at better than 80% coverage and at least 250 m average resolution. Higher-resolution images are also being acquired of targeted areas. The elemental remote sensing instruments, including the Gamma-Ray and Neutron Spectrometer and the X-Ray Spectrometer, are being operated nearly continuously and will establish the average surface abundances of most major elements. The Visible and Infrared Spectrograph channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer is acquiring a global map of spectral reflectance from 300 to 1450 nm wavelength at a range of incidence and emission

  15. Elevated Mercury Concentrations in Humans of Madre de Dios, Peru

    PubMed Central

    Ashe, Katy

    2012-01-01

    The enormous increase in practically unregulated mining in Madre de Dios Peru is leading to massive release of liquid elemental mercury to the environment. Rapidly increasing global prices for gold are causing a massive upsurge in artisanal mining in the Peruvian Amazon, considered to be one of the most biodiverse places on the planet. This study identifies the current levels of mercury in the human population, through identifying levels of total mercury in human hair in mining zones of Madre de Dios Department and in the nearby city of Puerto Maldonado. A regression analysis reveals that fish consumption, gender, and location of residence were significant indicators of mercury levels; while duration of residence and age had no significant relationship to mercury levels. Increased fish consumption levels were the strongest indicators of increased total mercury levels across the entire population. The levels of total mercury in hair was significantly (α = 0.05) higher in mining zones, than Puerto Maldonado. In both areas men had significantly higher levels than women, likely due to a difference in metabolism or varying levels of direct involvement in gold mining- a male predominated industry. This is the first study to show the health threat that mercury poses to this region, however further research needs to be done to gain a more refined understanding of the predominant routes of exposure in this population. PMID:22438911

  16. Elevated mercury concentrations in humans of Madre de Dios, Peru.

    PubMed

    Ashe, Katy

    2012-01-01

    The enormous increase in practically unregulated mining in Madre de Dios Peru is leading to massive release of liquid elemental mercury to the environment. Rapidly increasing global prices for gold are causing a massive upsurge in artisanal mining in the Peruvian Amazon, considered to be one of the most biodiverse places on the planet. This study identifies the current levels of mercury in the human population, through identifying levels of total mercury in human hair in mining zones of Madre de Dios Department and in the nearby city of Puerto Maldonado. A regression analysis reveals that fish consumption, gender, and location of residence were significant indicators of mercury levels; while duration of residence and age had no significant relationship to mercury levels. Increased fish consumption levels were the strongest indicators of increased total mercury levels across the entire population. The levels of total mercury in hair was significantly (α = 0.05) higher in mining zones, than Puerto Maldonado. In both areas men had significantly higher levels than women, likely due to a difference in metabolism or varying levels of direct involvement in gold mining- a male predominated industry. This is the first study to show the health threat that mercury poses to this region, however further research needs to be done to gain a more refined understanding of the predominant routes of exposure in this population.

  17. MESSENGER observations of magnetic reconnection in Mercury's magnetosphere.

    PubMed

    Slavin, James A; Acuña, Mario H; Anderson, Brian J; Baker, Daniel N; Benna, Mehdi; Boardsen, Scott A; Gloeckler, George; Gold, Robert E; Ho, George C; Korth, Haje; Krimigis, Stamatios M; McNutt, Ralph L; Raines, Jim M; Sarantos, Menelaos; Schriver, David; Solomon, Sean C; Trávnícek, Pavel; Zurbuchen, Thomas H

    2009-05-01

    Solar wind energy transfer to planetary magnetospheres and ionospheres is controlled by magnetic reconnection, a process that determines the degree of connectivity between the interplanetary magnetic field (IMF) and a planet's magnetic field. During MESSENGER's second flyby of Mercury, a steady southward IMF was observed and the magnetopause was threaded by a strong magnetic field, indicating a reconnection rate ~10 times that typical at Earth. Moreover, a large flux transfer event was observed in the magnetosheath, and a plasmoid and multiple traveling compression regions were observed in Mercury's magnetotail, all products of reconnection. These observations indicate that Mercury's magnetosphere is much more responsive to IMF direction and dominated by the effects of reconnection than that of Earth or the other magnetized planets.

  18. The Mercury Laser Altimeter Instrument for the MESSENGER Mission

    NASA Technical Reports Server (NTRS)

    Cavanaugh, John F.; Smith, James C.; Sun, Xiaoli; Bartels, Arlin E.; Ramos-Izquierdo, Luis; Krebs, Danny J.; Novo-Gradac, Anne marie; McGarry, Jan F.; Trunzo, Raymond; Britt, Jamie L.

    2006-01-01

    The Mercury Laser Altimeter (MLA) is one of the payload science instruments on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, which launched on 3 August 2004. The altimeter will measure the round trip time-of-flight of transmitted laser pulses reflected from the surface of the planet that, in combination with the spacecraft orbit position and pointing data, gives a high-precision measurement of surface topography referenced to Mercury's center of mass. The altimeter measurements will be used to determine the planet's forced librations by tracking the motion of large-scale topographic features as a function of time. MLA's laser pulse energy monitor and the echo pulse energy estimate will provide an active measurement of the surface reflectivity at 1064 nm. This paper describes the instrument design, prelaunch testing, calibration, and results of post-launch testing.

  19. Planet Formation - Overview

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2005-01-01

    Modern theories of star and planet formation are based upon observations of planets and smaller bodies within our own Solar System, exoplanets &round normal stars and of young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path.

  20. Planet Formation - Overview

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2005-01-01

    Modern theories of star and planet formation are based upon observations of planets and smaller bodies within our own Solar System, exoplanets &round normal stars and of young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path.

  1. Detecting Extrasolar Planets Directly

    NASA Astrophysics Data System (ADS)

    Guenther, E. W.; Neuhäuser, R.; Huélamo, N.; Ott, T.; Brandner, W.; Alves, J.; Comerón, F.; Eckart, A.; Hatzes, A.

    Up to now, all extrasolar planets have been found by means of indirect methods. Direct detection of planets orbiting even the nearest stars seems at first glance to be impossible with present day equipment, because of the enormous difference in brightness between the star and the planet, and the small angular separation between them. However, young planets which are still in the contraction phase of evolution are comparatively bright in the infrared, and since many of the extrasolar planets detected have excentric orbits, where they are most of the time at a relatively large distance from the stars, the prospect of detecting young planets directly is much better. In fact, it is principle be possible to detect an extrasolar giant planet, if the planet is younger than 100 millon years, and if the distance is less than 100 pc. Three years ago we thus have embarked on a survey to observe more than one-hundred young, nearby stars in the near infrared. In this talk, we will review the status of the survey. In order to find out whether these stars have additionally a planet at a small distance from the star, we also carried out sensitive radial velocity observation of a subsample using an iodine-cell and the Echelle spectrograph of the Alfred-Jensch Telescope in Tautenburg.

  2. Water in the terrestrial planets and the moon

    SciTech Connect

    Liu, L.G.

    1988-04-01

    Current thermal models for the terrestrial planets, with the exception of Mercury, point to the probability of a partial melting zone's presence in the mantles of both Venus and Mars, but not in that of the earth; this is attested by the fact that plate tectonics is not apparent on Mars and Venus. In addition, the CO/sub 2/-dominated atmospheres of Venus and Mars may indicate that a large-scale hydrosphere has never (or only very briefly) existed on these planets. Most of the free H/sub 2/O above the water line of Venus and Mars is probably still trapped inside mantle melts. 37 references.

  3. Exploring Disks Around Planets

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-07-01

    Giant planets are thought to form in circumstellar disks surrounding young stars, but material may also accrete into a smaller disk around the planet. Weve never detected one of these circumplanetary disks before but thanks to new simulations, we now have a better idea of what to look for.Image from previous work simulating a Jupiter-mass planet forming inside a circumstellar disk. The planet has its own circumplanetary disk of accreted material. [Frdric Masset]Elusive DisksIn the formation of giant planets, we think the final phase consists of accretion onto the planet from a disk that surrounds it. This circumplanetary disk is important to understand, since it both regulates the late gas accretion and forms the birthplace of future satellites of the planet.Weve yet to detect a circumplanetary disk thus far, because the resolution needed to spot one has been out of reach. Now, however, were entering an era where the disk and its kinematics may be observable with high-powered telescopes (like the Atacama Large Millimeter Array).To prepare for such observations, we need models that predict the basic characteristics of these disks like the mass, temperature, and kinematic properties. Now a researcher at the ETH Zrich Institute for Astronomy in Switzerland, Judit Szulgyi, has worked toward this goal.Simulating CoolingSzulgyi performs a series of 3D global radiative hydrodynamic simulations of 1, 3, 5, and 10 Jupiter-mass (MJ) giant planets and their surrounding circumplanetary disks, embedded within the larger circumstellar disk around the central star.Density (left column), temperature (center), and normalized angular momentum (right) for a 1 MJ planet over temperatures cooling from 10,000 K (top) to 1,000 K (bottom). At high temperatures, a spherical circumplanetary envelope surrounds the planet, but as the planet cools, the envelope transitions around 64,000 K to a flattened disk. [Szulgyi 2017]This work explores the effects of different planet temperatures and

  4. Making Mercury's Core with Light Elements

    NASA Technical Reports Server (NTRS)

    Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Ross, D. Kent

    2016-01-01

    Recent results obtained from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft showed the surface of Mercury has low FeO abundances (less than 2 wt%) and high S abundances (approximately 4 wt%), suggesting the oxygen fugacity of Mercury's surface materials is somewhere between 3 to 7 log10 units below the IW buffer. The highly reducing nature of Mercury has resulted in a relatively thin mantle and a large core that has the potential to exhibit an exotic composition in comparison to the other terrestrial planets. This exotic composition may extend to include light elements (e.g., Si, C, S). Furthermore, has argued for a possible primary floatation crust on Mercury composed of graphite, which may require a core that is C-saturated. In order to investigate mercurian core compositions, we conducted piston cylinder experiments at 1 GPa, from 1300 C to 1700 C, using a range of starting compositions consisting of various Si-Fe metal mixtures (Si5Fe95, Si10Fe90, Si22Fe78, and Si35Fe65). All metals were loaded into graphite capsules used to ensure C-saturation during the duration of each experimental run. Our experiments show that Fe-Si metallic alloys exclude carbon relative to more Fe-rich metal. This exclusion of carbon commences within the range of 5 to 10 wt% Si. These results indicate that if Mercury has a Si-rich core (having more than approximately 5 wt% silicon), it would have saturated in carbon at low C abundances allowing for the possible formation of a graphite floatation crust as suggested by. These results have important implications for the thermal and magmatic evolution of Mercury.

  5. Impact cratering of the terrestrial planets and the Moon during the giant planet instability

    NASA Astrophysics Data System (ADS)

    Roig, Fernando Virgilio; Nesvorny, David; Bottke, William

    2016-10-01

    The dynamical instability of the giant planets and the planetesimal driven migration both have major implications for the crater record of the terrestrial planets and the Moon. The crater record can thus provide contraints to the behavior of the planets in the early Solar System. Here we determine the impact fluxes and the crater production rates on the terrestrial planets and the Moon from impactors originating in the primordial asteroid main belt (2.1 to 3.2 au) and the E-belt (1.5 to 2.1 au - Bottke et al. 2012). We determine the impact flux over the age of the Solar System, with particular focus on the instability of the giant planets in the jumping Jupiter model. We start with a population of asteroids uniformly distributed in the orbital parameters space, and numerically evolve them as test particles under the gravitational perturbations of the giant and terrestrial planets. We test the effects on this population due to different jumping Jupiter evolutions (the idealized jump as in Bottke et al. 2012 or models taken from Nesvorny & Morbidelli 2012). The number of impacts is determined by applying Opik's theory. We compute the impact rates on different targets (Mercury, Venus, Earth, Moon, and Mars) and from different source regions in the asteroid belt (E-belt, inner belt, outer belt). By properly calibrating the impact rates, and using crater scaling laws, we estimate the number and size distribution of craters. We show how the impact flux and crater production rates depend on the different parameters of the model such as the initial orbital distribution of the asteroids, time of the instability, different evolution of the planets, initial size distribution of the impactors, etc.

  6. Accretion of the terrestrial planets. II

    NASA Technical Reports Server (NTRS)

    Weidenschilling, S. J.

    1976-01-01

    The theory of gravitational accretion of the terrestrial planets is examined. The concept of a 'closed feeding zone' is somewhat unrealistic, but provides a lower bound on the accretion time. A velocity relation for planetesimals which includes an initial velocity component is suggested. The orbital parameters of the planetesimals and the dimensions of the feeding zone are related to their relative velocities. The assumption of an initial velocity does not seriously change the accretion time. Mercury, Venus, and the earth have accretion times on the order of 100 million years. Mars requires well over one billion years to accrete by the same assumptions. The lunar cratering history makes a late formation of Mars unlikely. If Mars is as old as the earth, nongravitational forces or a violation of the feeding zone concept is required. One such possibility is the removal of matter from the zone of Mars by Jupiter's influence. The final sweeping up by Mars would result in the scattering of a considerable mass among the other terrestrial planets. The late postaccretional bombardments inferred for the moon and Mercury may have had this source.

  7. Mercury Project

    NASA Image and Video Library

    1958-06-24

    Testing of Mercury Capsule Shape A by the Hydrodynamics Division of Langley. Joseph Shortal wrote (vol. 3, p. 19): The Hydrodynamics Division provided assistance in determining landing loads. In this connection, after PARD engineers had unofficially approached that division to make some water impact tests with the boilerplate capsule, J.B. Parkinson, Hydrodynamics Chief visited Shortal to find out if the request had his support. Finding out that it did, Parkinson said, Its your capsule. If you want us to drop it in the water, we will do it. From Shortal (Vol. 3, p. 16): The basic design of the capsule was made by M.A. Faget and his coworkers at PARD during the winter of 1957-1958. It was natural, then, that extensive use was made of the facilities at Wallops during the development of the spacecraft. The tests at Wallops consisted of 26 full-size capsules, either launched from the ground by rocket power or dropped from airplanes at high altitude and 28 scaled models, either rocket boosted or released from balloons. Emphasis in the Wallops program was on dynamic stability and aerodynamic heating of the capsule, and effectiveness of the pilot-escape and parachute-recovery systems. The biggest part of the Wallops program was the series of full-size capsules, rocket launched with the Little Joe booster, developed especially for Mercury. -- Published in Joseph A. Shortal, History of Wallops Station: Origins and Activities Through 1949, (Wallops Island, VA: National Aeronautics and Space Administration, Wallops Station, nd), Comment Edition.

  8. Secular Trends in the Mean Longitudes of Planets Derived from Optical Observations

    NASA Astrophysics Data System (ADS)

    Kolesnik, Yuri B.; Masreliez, C. Johan

    2004-08-01

    About 240,000 worldwide optical observations of the Sun, Mercury, and Venus, accumulated during the entire era of classical astrometry from James Bradley up to the present, are used to analyze the secular longitude variations of the innermost planets. A reduction method relating historical planetary observations to the Hipparcos reference frame is presented. Secular trends in the longitudes of the Sun, Mercury, and Venus with respect to the ephemeris DE405 are estimated for the time span 1750-2000.

  9. Global Trends in Mercury Management

    PubMed Central

    Choi, Kyunghee

    2012-01-01

    The United Nations Environmental Program Governing Council has regulated mercury as a global pollutant since 2001 and has been preparing the mercury convention, which will have a strongly binding force through Global Mercury Assessment, Global Mercury Partnership Activities, and establishment of the Open-Ended Working Group on Mercury. The European Union maintains an inclusive strategy on risks and contamination of mercury, and has executed the Mercury Export Ban Act since December in 2010. The US Environmental Protection Agency established the Mercury Action Plan (1998) and the Mercury Roadmap (2006) and has proposed systematic mercury management methods to reduce the health risks posed by mercury exposure. Japan, which experienced Minamata disease, aims vigorously at perfection in mercury management in several ways. In Korea, the Ministry of Environment established the Comprehensive Plan and Countermeasures for Mercury Management to prepare for the mercury convention and to reduce risks of mercury to protect public health. PMID:23230466

  10. Global trends in mercury management.

    PubMed

    Kim, Dae-Seon; Choi, Kyunghee

    2012-11-01

    The United Nations Environmental Program Governing Council has regulated mercury as a global pollutant since 2001 and has been preparing the mercury convention, which will have a strongly binding force through Global Mercury Assessment, Global Mercury Partnership Activities, and establishment of the Open-Ended Working Group on Mercury. The European Union maintains an inclusive strategy on risks and contamination of mercury, and has executed the Mercury Export Ban Act since December in 2010. The US Environmental Protection Agency established the Mercury Action Plan (1998) and the Mercury Roadmap (2006) and has proposed systematic mercury management methods to reduce the health risks posed by mercury exposure. Japan, which experienced Minamata disease, aims vigorously at perfection in mercury management in several ways. In Korea, the Ministry of Environment established the Comprehensive Plan and Countermeasures for Mercury Management to prepare for the mercury convention and to reduce risks of mercury to protect public health.

  11. New Jersey mercury regulations

    SciTech Connect

    Elias, D.F.; Corbin, W.E.

    1996-12-31

    Mercury, or quicksilver, and its major ore cinnabar (HgS) have been known for thousands of years. Health effects from mercury such as dementia were known as early as the late 19th century ({open_quotes}mad as a hatter{close_quotes}). In the 1960`s and 1970`s, reported levels of mercury in tuna reawakened public awareness of mercury pollution. In the 1970`s, major epidemics of acute mercury poisoning were reported in Japan and Iraq. These incidents highlighted the extreme health risks, such as kidney damage, birth defects, and death, associated with severe mercury poisoning. Fetuses and young children are particularly vulnerable since mercury poisoning can damage growing neural tissues. Recently, the perception of mercury as a dangerous pollutant has been on the rise. Advisories warning the public to avoid or reduce the consumption of freshwater fish caught in specific waterbodies due to mercury contamination have been issued in numerous states. The discovery of mercury in {open_quotes}pristine{close_quotes} lakes in the United States, Canada, and Scandinavia, remote from industry and any known mercury sources, has focused attention on atmospheric emissions of mercury as potential significant sources of mercury.

  12. Did 26Al and impact-induced heating differentiate Mercury?

    NASA Astrophysics Data System (ADS)

    Bhatia, G. K.; Sahijpal, S.

    2017-02-01

    Numerical models dealing with the planetary scale differentiation of Mercury are presented with the short-lived nuclide, 26Al, as the major heat source along with the impact-induced heating during the accretion of planets. These two heat sources are considered to have caused differentiation of Mars, a planet with size comparable to Mercury. The chronological records and the thermal modeling of Mars indicate an early differentiation during the initial 1 million years (Ma) of the formation of the solar system. We theorize that in case Mercury also accreted over an identical time scale, the two heat sources could have differentiated the planets. Although unlike Mars there is no chronological record of Mercury's differentiation, the proposed mechanism is worth investigation. We demonstrate distinct viable scenarios for a wide range of planetary compositions that could have produced the internal structure of Mercury as deduced by the MESSENGER mission, with a metallic iron (Fe-Ni-FeS) core of radius 2000 km and a silicate mantle thickness of 400 km. The initial compositions were derived from the enstatite and CB (Bencubbin) chondrites that were formed in the reducing environments of the early solar system. We have also considered distinct planetary accretion scenarios to understand their influence on thermal processing. The majority of our models would require impact-induced mantle stripping of Mercury by hit and run mechanism with a protoplanet subsequent to its differentiation in order to produce the right size of mantle. However, this can be avoided if we increase the Fe-Ni-FeS contents to 71% by weight. Finally, the models presented here can be used to understand the differentiation of Mercury-like exoplanets and the planetary embryos of Venus and Earth.

  13. Name That Planet!

    ERIC Educational Resources Information Center

    Beck, Judy; Rust, Cindy

    2002-01-01

    Presents an activity in which students in groups explore one planet in the solar system and present their findings to the whole class. Focuses on the planet's location in the solar system, geological features, rate of revolutions, and calendar year. (YDS)

  14. Gas Planet Orbits

    NASA Image and Video Library

    2008-08-19

    Jupiter, Saturn, Uranus, and Neptune are known as the jovian Jupiter-like planets because they are all gigantic compared with Earth, and they have a gaseous nature. This diagram shows the approximate distance of the jovian planets from the Sun.

  15. Planets in Motion

    ERIC Educational Resources Information Center

    Riddle, Bob

    2005-01-01

    All the planets in the solar system revolve around the Sun in the same direction, clockwise when viewed from above the North Pole. This is referred to as direct motion. From the perspective on the Earth's surface, the planets travel east across the sky in relation to the background of stars. The Sun also moves eastward daily, but this is an…

  16. Outer Planet Icy Satellites

    NASA Technical Reports Server (NTRS)

    Buratti, B.

    1994-01-01

    An outer planet icy satellite is any one of the celestial bodies in orbit around Jupiter, Saturn, Uranus, Neptune, or Pluto. They range from large, planet-like geologically active worlds with significant atmospheres to tiny irregular objects tens of kilometers in diameter. These bodies are all believed to have some type of frozen volatile, existing alone or in combination with other volatiles.

  17. March of the Planets

    ERIC Educational Resources Information Center

    Thompson, Bruce

    2007-01-01

    The motion of the planets in their orbits can be demonstrated to students by using planetarium software programs. These allow time to be sped up so that the relative motions are readily observed. However, it is also valuable to have the students understand the real speed of the planets in their orbits. This paper describes an exercise that gives…

  18. Name That Planet!

    ERIC Educational Resources Information Center

    Beck, Judy; Rust, Cindy

    2002-01-01

    Presents an activity in which students in groups explore one planet in the solar system and present their findings to the whole class. Focuses on the planet's location in the solar system, geological features, rate of revolutions, and calendar year. (YDS)

  19. March of the Planets

    ERIC Educational Resources Information Center

    Thompson, Bruce

    2007-01-01

    The motion of the planets in their orbits can be demonstrated to students by using planetarium software programs. These allow time to be sped up so that the relative motions are readily observed. However, it is also valuable to have the students understand the real speed of the planets in their orbits. This paper describes an exercise that gives…

  20. Planets in Motion

    ERIC Educational Resources Information Center

    Riddle, Bob

    2005-01-01

    All the planets in the solar system revolve around the Sun in the same direction, clockwise when viewed from above the North Pole. This is referred to as direct motion. From the perspective on the Earth's surface, the planets travel east across the sky in relation to the background of stars. The Sun also moves eastward daily, but this is an…

  1. European astronomers observe first evaporating planet

    NASA Astrophysics Data System (ADS)

    2003-03-01

    planet’s upper atmosphere under the searing heat from the star. "The atmosphere is heated, the hydrogen escapes the planet's gravitational pull and is pushed away by the starlight, fanning out in a large tail behind the planet - like that of a comet," says Alain Lecavelier des Etangs, of the Institut d’Astrophysique de Paris. Astronomers estimate the amount of hydrogen gas escaping from HD 209458b to be at least 10 000 tonnes per second, but possibly much more. The planet may therefore already have lost quite a lot of its mass. HD 209458b belongs to a type of extrasolar planet known as ‘hot Jupiters’. These planets orbit precariously close to their stars. They are giant gaseous planets that must have formed in the cold outer reaches of the star system and then spiralled into their close orbits. This new discovery might help explain why ‘hot Jupiters’ so often orbit a few million kilometres from their parent stars. They are not usually found much closer than 7 million kilometres, the distance in the case of HD 209458b. Currently, the closest is 5.7 million kilometres. Hot Jupiters have orbits as brief as 3 days, but no less. Perhaps the evaporation of the atmosphere plays a role in setting an inner boundary for orbits of hot Jupiters. Notes for editors HD 209458b has a diameter 1.3 times that of Jupiter, and two-thirds the mass. Its orbit is one-eighth the size of Mercury's orbit around the Sun. The parent star is similar to our Sun and lies 150 light-years from Earth. It is visible with binoculars as a seventh magnitude star in the constellation of Pegasus. In 1999, this star suddenly entered the astronomical Hall of Fame when the extrasolar planet HD 209458b passed in front of it and partly eclipsed it. This was the first confirmed transiting extrasolar planet ever discovered. In 2001, Hubble detected the element sodium in the lower part of HD 209458b’s atmosphere, the first signature of an atmosphere on any extrasolar planet. The team is composed of A

  2. 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.

  3. Iceball Planet Artist's Concept

    NASA Image and Video Library

    2017-04-26

    This artist's concept shows OGLE-2016-BLG-1195Lb, a planet discovered through a technique called microlensing. The planet was reported in a 2017 study in the Astrophysical Journal Letters. Study authors used the Korea Microlensing Telescope Network (KMTNet), operated by the Korea Astronomy and Space Science Institute, and NASA's Spitzer Space Telescope, to track the microlensing event and find the planet. Although OGLE-2016-BLG-1195Lb is about the same mass as Earth, and the same distance from its host star as our planet is from our sun, the similarities may end there. This planet is nearly 13,000 light-years away and orbits a star so small, scientists aren't sure if it's a star at all. https://photojournal.jpl.nasa.gov/catalog/PIA21430

  4. Planets in Transit V Passages of Discovery

    NASA Astrophysics Data System (ADS)

    Castellano, T. P.

    2003-05-01

    Eclipses of the Sun have long influenced culture, history, and science. The analogous but much more subtle phenomena of a transit of the Sun by Mercury was first predicted by Johannes Kepler. Soon, predictions of transits of Venus inspired bold expeditions to better understand the scale of our solar system. These passages of discovery sometimes succeeded scientifically but always captured the public imagination and played an unexpected role in history. The possibility of detecting planets outside the solar system by the transit method was first outlined by Otto Struve in 1952. Early inquiries usually assumed that extrasolar planetary systems would have a distribution of planetary radii and orbital sizes like the solar system. The detection of transits from the ground in such systems would be daunting. The recent, unexpected discovery of a class of extrasolar planets (by the radial velocity technique) with orbital periods less than a week and masses near to the planet Jupiter has resulted in a resurgence of interest in the transit method. These so called "hot Jupiters", can produce transits that are likely enough, frequent enough, the transit method. These so called "hot Jupiters", can produce transits that are likely enough, frequent enough, and deep enough that ground-based transit searches can be successful. In November 1999, a planet orbiting the star HD 209458 was found to transit, and many measurements of the transit have since been made that challenge formation and evolution theories. Numerous ground based searches for transits are now underway. Several planned high precision space-based missions designed to detect transits of earth-sized planets, also have the potential to detect transits of hundreds of "hot Jupiters". These efforts and the upcoming transit of the Sun by Venus on June 8, 2004 present an opportunity for transits to once again capture the public imagination and perhaps play a role in history.

  5. Minamata Convention on Mercury

    EPA Pesticide Factsheets

    On November 6, 2013 the United States signed the Minamata Convention on Mercury, a new multilateral environmental agreement that addresses specific human activities which are contributing to widespread mercury pollution

  6. Basic Information about Mercury

    MedlinePlus

    ... exposures to methylmercury than other animals in water ecosystems. Predators that eat these birds and mammals are ... Service (NPS): Effects of Air Toxics/Mercury on Ecosystems U.S. Geological Survey (USGS): Mercury in the Environment ...

  7. Proposed Missions - Terrestrial Planet Finder

    NASA Image and Video Library

    2003-06-20

    NASA Terrestrial Planet Finder will use multiple telescopes working together to take family portraits of stars and their orbiting planets and determine which planets may have the right chemistry to sustain life.

  8. Mercury's Surface Magnetic Field Determined from Proton-Reflection Magnetometry

    NASA Technical Reports Server (NTRS)

    Winslow, Reka M.; Johnson, Catherine L.; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Lillis, Robert J.; Korth, Haje; Slavin, James A.; Solomon, Sean C.; Zurbuchen, Thomas H.; Zuber, Maria T.

    2014-01-01

    Solar wind protons observed by the MESSENGER spacecraft in orbit about Mercury exhibit signatures of precipitation loss to Mercury's surface. We apply proton-reflection magnetometry to sense Mercury's surface magnetic field intensity in the planet's northern and southern hemispheres. The results are consistent with a dipole field offset to the north and show that the technique may be used to resolve regional-scale fields at the surface. The proton loss cones indicate persistent ion precipitation to the surface in the northern magnetospheric cusp region and in the southern hemisphere at low nightside latitudes. The latter observation implies that most of the surface in Mercury's southern hemisphere is continuously bombarded by plasma, in contrast with the premise that the global magnetic field largely protects the planetary surface from the solar wind.

  9. Production of simple molecules on the surface of Mercury

    NASA Technical Reports Server (NTRS)

    Gibson, E. K., Jr.

    1977-01-01

    Lunar sample studies have shown that solar-wind irradiation of the lunar surface has produced a variety of low-molecular-weight compounds. Analysis of the lunar soils has revealed the presence of H2, CH4, H2O, N2, CO, CO2, He, Ne and other components which are extralunar. Irradiation experiments on lunar materials and analogs have shown that solar-wind and solar-flare irradiation of the lunar surface produces selected low-molecular-weight components. Solar-wind irradiation of Mercury's surface should also produce a wide variety of low-molecular-weight species because of the increased solar flux, which results from Mercury being nearer the sun than the moon. The thermal regime of Mercury's surface would result in thermal evaporation of low-temperature components followed by 'cold-trapping' on the night-time side of the planet. Such desorption-adsorption processes assist chemical weathering of Mercury's regolith.

  10. Production of simple molecules on the surface of Mercury

    NASA Technical Reports Server (NTRS)

    Gibson, E. K., Jr.

    1977-01-01

    Lunar sample studies have shown that solar-wind irradiation of the lunar surface has produced a variety of low-molecular-weight compounds. Analysis of the lunar soils has revealed the presence of H2, CH4, H2O, N2, CO, CO2, He, Ne and other components which are extralunar. Irradiation experiments on lunar materials and analogs have shown that solar-wind and solar-flare irradiation of the lunar surface produces selected low-molecular-weight components. Solar-wind irradiation of Mercury's surface should also produce a wide variety of low-molecular-weight species because of the increased solar flux, which results from Mercury being nearer the sun than the moon. The thermal regime of Mercury's surface would result in thermal evaporation of low-temperature components followed by 'cold-trapping' on the night-time side of the planet. Such desorption-adsorption processes assist chemical weathering of Mercury's regolith.

  11. Mercury's thermal history and the generation of its magnetic field

    NASA Technical Reports Server (NTRS)

    Schubert, G.; Ross, M. N.; Stevenson, D. J.; Spohn, T.

    1988-01-01

    Thermal history of Mercury's interior is examined using the model of Stevenson et al. (1983), extended to include the effects of tidal heating in Mercury's solid inner core. The implications of Mercury's thermal history for the source of the planet's magnetic field are discussed. It is shown that the major results of this model are similar to the results obtained with the Stevenson et al. model, except for the addition of inner-core tidal dissipation. It is concluded that the extended model properly characterizes Mercury's internal structure and thermal history, and that the criteria for dynamo generation are not properly satisfied. Alternative explanations, including the possibility of a weak thermoelectric dynamo, are examined.

  12. The Soviet-American Conference on Cosmochemistry of the Moon and Planets, Part 1

    NASA Technical Reports Server (NTRS)

    Pomeroy, J. H. (Editor); Hubbard, N. J. (Editor)

    1977-01-01

    The basic goal of the conference was consideration of the origin of the planets of the solar system, based on the physical and chemical data obtained by study of the material of the moon and planets. Papers at the conference were presented in the following sessions: (1) Differentiation of the material of the moon and planets; (2) The thermal history of the moon; (3) Lunar gravitation and magnetism; (4) Chronology of the moon, planets, and meteorites; (5) The role of exogenic factors in the formation of the lunar surface; (6) Cosmochemical hypotheses about the origin and evolution of the moon and planets; and (7) New data about the planets Mercury, Venus, Mars, and Jupiter.

  13. Changing Perspectives on Mercury and the Moon

    NASA Astrophysics Data System (ADS)

    Denevi, Brett W.

    2015-11-01

    Airless, cratered, and not so different in size, the Moon and Mercury form a natural pair in the inner Solar System. For decades after the 1974 and 1975 Mariner 10 flybys of Mercury, with little compositional information, no concrete evidence for volcanism, and images of less than half of the planet, it was thought that Mercury’s surface may be similar to the lunar highlands: an ancient anorthositic flotation crust subsequently shaped mainly by impact cratering. However, observations from the recently completed MESSENGER mission to Mercury have upended our view of the innermost planet, revealing, for example, a crust that may be rich in graphite and that has been extensively resurfaced by volcanic activity, and geologic activity that may continue today to produce enigmatic “hollows” - a crust very different from that of the Moon. Meanwhile, the Moon has undergone its own revolution, as data from recent spacecraft such as the Lunar Reconnaissance Orbiter reveal sites of silicic volcanism indicative of complex differentiation in the mantle, tectonic activity that may be ongoing, recent volcanic activity that alters the paradigm that volcanism died on the Moon over a billion years ago, and evidence that the early chronology of the inner Solar System may not be as well known as once thought. As our views of these two bodies evolve, a new understanding of their differences informs our knowledge of the variety of processes and styles of planetary evolution, and their similarities point to commonalities among all airless bodies.

  14. Mercury Surveillance Program

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Background on mercury exposure is presented including forms, sources, permissible exposure limits, and physiological effects. The purpose of the Mercury Surveillance Program at LeRC is outlined, and the specifics of the Medical Surveillance Program for Mercury Exposure at LeRC are discussed.

  15. Dental amalgam and mercury

    SciTech Connect

    Mackert, J.R. Jr. )

    1991-08-01

    This paper looks at the issues of the current amalgam controversy: the daily dose of mercury from amalgam, hypersensitivity to mercury, claims of adverse effects from amalgam mercury and alleged overnight 'cures.' In addition, the toxicity and allergenicity of the proposed alternative materials are examined with the same kind of scrutiny applied by the anti-amalgam group to dental amalgam. 100 references.

  16. Ancient Maya Mercury

    NASA Astrophysics Data System (ADS)

    Pendergast, David M.

    1982-08-01

    Discovery of mercury in an ancient Maya offering at Lamanai, Belize, has stimulated examination of possible sources of the material in the Maya area. Two zones of cinnabar and native mercury deposits can be defined in the Maya highlands, and the presence of the native metal suggests that the ancient Maya collected rather than extracted the mercury from ore.

  17. Mercury in the environment

    NASA Technical Reports Server (NTRS)

    Fulkerson, W.; Lyon, W. S.; Shults, W. D.; Wallace, R. A.

    1972-01-01

    Problems in assessing mercury concentrations in environmental materials are discussed. Data for situations involving air, water, rocks, soils, sediments, sludges, fossil fuels, plants, animals, foods, and man are drawn together and briefly evaluated. Details are provided regarding the toxicity of mercury along with tentative standards and guidelines for mercury in air, drinking water, and food.

  18. Ballistic mode Mercury orbiter missions.

    NASA Technical Reports Server (NTRS)

    Hollenbeck, G. R.

    1973-01-01

    The MVM'73 Mercury flyby mission will initiate exploration of this unique planet. No firm plans for follow-on investigations have materialized due to the difficult performance requirements of the next logical step, an orbiter mission. Previous investigations of ballistic mode flight opportunities have indicated requirements for a Saturn V class launch vehicle. Consequently, most recent effort has been oriented to use of solar electric propulsion. More comprehensive study of the ballistic flight mode utilizing Venus gravity-assist has resulted in identification of timely high-performance mission opportunities compatible with programmed launch vehicles and conventional spacecraft propulsion technologies. A likely candidate for an initial orbiter mission is a 1980 opportunity which offers net orbiter spacecraft mass of about 435 kg with the Titan IIIE/Centaur launch vehicle and single stage solid propulsion for orbit insertion.

  19. An Investigation of Trajectories of Atoms in Mercury's Exosphere

    NASA Astrophysics Data System (ADS)

    Bradley, Eric Todd

    2016-10-01

    Mercury's neutral exosphere consists of atoms or molecules ejected from the surface that are on individual trajectories that may re-impact the surface if there is insufficient energy to escape the gravity of the planet. This is an investigation of how the radiation pressure, orbital acceleration of the planet, and planetary rotation combine together to produce complicated trajectories. Because of Mercury's non-zero eccentricity the planet is not in uniform circular motion, which leads to radial and tangential accelerations that vary throughout the Mercury year. Besides radiation pressure the trajectory of an exospheric atom is affected by the planet accelerating during the time of flight of the atom that 1) causes the atom's position with respect to the ejection point to vary in a manner that is different than if the planet were not accelerating and 2) causes the planet-atom distance to vary in a manner that is different than for a typical ballistic trajectory resulting in variation of the gravitational force that the planet exerts on the atom. These effects are small but persistent and affect where the atom re-impacts the surface, which may lead to asymmetrical distributions of atoms in the surface regolith and exosphere.Preliminary results from simulations of ejected atoms that include 1) radiation pressure that varies with the atom's velocity due to Doppler shifting, 2) radial and tangential accelerations of the planet, and 3) the variation of the planet's gravity on the atom with distance above the planet show that atoms ejected at low energies normal to the surface from the subsolar point re-impact on the dusk side hemisphere of the planet. However atoms ejected at high energies normal to the surface from the subsolar point re-impact on the dawn side hemisphere of the planet. A fraction of atoms ejected normal to the surface from the dawn terminator within an energy range that results in the atom re-impacting and sticking to the night side surface behind the

  20. Mercury's rotational state from combined MESSENGER laser altimeter and image data

    NASA Astrophysics Data System (ADS)

    Stark, Alexander; Oberst, Jürgen; Preusker, Frank; Margot, Jean-Luc; Phillips, Roger J.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.; Solomon, Sean C.

    2016-04-01

    With orbital data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, we measured the rotational state of Mercury. We developed a novel approach that combined digital terrain models from stereo images (stereo DTMs) and laser altimeter data, and we applied it to 3 years of MESSENGER observations. We find a large libration amplitude, which in combination with the measured obliquity confirms that Mercury possesses a liquid outer core. Our results confirm previous Earth-based observations of Mercury's rotational state. However, we measured a rotation rate that deviates significantly from the mean resonant rotation rate. The larger rotation rate can be interpreted as the signature of a long-period libration cycle. From these findings we derived new constraints on the interior structure of Mercury. The measured rotational parameters define Mercury's body-fixed frame and are critical for the coordinate system of the planet as well as for planning the future BepiColombo spacecraft mission.

  1. MESSENGER observations of the composition of Mercury's ionized exosphere and plasma environment.

    PubMed

    Zurbuchen, Thomas H; Raines, Jim M; Gloeckler, George; Krimigis, Stamatios M; Slavin, James A; Koehn, Patrick L; Killen, Rosemary M; Sprague, Ann L; McNutt, Ralph L; Solomon, Sean C

    2008-07-04

    The region around Mercury is filled with ions that originate from interactions of the solar wind with Mercury's space environment and through ionization of its exosphere. The MESSENGER spacecraft's observations of Mercury's ionized exosphere during its first flyby yielded Na+, O+, and K+ abundances, consistent with expectations from observations of neutral species. There are increases in ions at a mass per charge (m/q) = 32 to 35, which we interpret to be S+ and H2S+, with (S+ + H2S+)/(Na+ + Mg+) = 0.67 +/- 0.06, and from water-group ions around m/q = 18, at an abundance of 0.20 +/- 0.03 relative to Na+ plus Mg+. The fluxes of Na+, O+, and heavier ions are largest near the planet, but these Mercury-derived ions fill the magnetosphere. Doubly ionized ions originating from Mercury imply that electrons with energies less than 1 kiloelectron volt are substantially energized in Mercury's magnetosphere.

  2. Planetary science. Low-altitude magnetic field measurements by MESSENGER reveal Mercury's ancient crustal field.

    PubMed

    Johnson, Catherine L; Phillips, Roger J; Purucker, Michael E; Anderson, Brian J; Byrne, Paul K; Denevi, Brett W; Feinberg, Joshua M; Hauck, Steven A; Head, James W; Korth, Haje; James, Peter B; Mazarico, Erwan; Neumann, Gregory A; Philpott, Lydia C; Siegler, Matthew A; Tsyganenko, Nikolai A; Solomon, Sean C

    2015-05-22

    Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury's crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury's history. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust inferred from MESSENGER elemental composition data.

  3. Polygonal Craters on Dwarf-Planet Ceres

    NASA Astrophysics Data System (ADS)

    Otto, K. A.; Jaumann, R.; Krohn, K.; Buczkowski, D. L.; von der Gathen, I.; Kersten, E.; Mest, S. C.; Preusker, F.; Roatsch, T.; Schenk, P. M.; Schröder, S.; Schulzeck, F.; Scully, J. E. C.; Stepahn, K.; Wagner, R.; Williams, D. A.; Raymond, C. A.; Russell, C. T.

    2015-10-01

    With approximately 950 km diameter and a mass of #1/3 of the total mass of the asteroid belt, (1) Ceres is the largest and most massive object in the Main Asteroid Belt. As an intact proto-planet, Ceres is key to understanding the origin and evolution of the terrestrialplanets [1]. In particular, the role of water during planet formation is of interest, because the differentiated dwarf-planet is thought to possess a water rich mantle overlying a rocky core [2]. The Dawn space craft arrived at Ceres in March this year after completing its mission at (4) Vesta. At Ceres, the on-board Framing Camera (FC) collected image data which revealed a large variety of impact crater morphologies including polygonal craters (Figure 1). Polygonal craters show straight rim sections aligned to form an angular shape. They are commonly associated with fractures in the target material. Simple polygonal craters develop during the excavation stage when the excavation flow propagates faster along preexisting fractures [3, 5]. Complex polygonal craters adopt their shape during the modification stage when slumping along fractures is favoured [3]. Polygonal craters are known from a variety of planetary bodies including Earth [e.g. 4], the Moon [e.g. 5], Mars [e.g. 6], Mercury [e.g. 7], Venus [e.g. 8] and outer Solar System icy satellites [e.g. 9].

  4. Tectonic evolution of the terrestrial planets.

    PubMed

    Head, J W; Solomon, S C

    1981-07-03

    The style and evolution of tectonics on the terrestrial planets differ substantially. The style is related to the thickness of the lithosphere and to whether the lithosphere is divided into distinct, mobile plates that can be recycled into the mantle, as on Earth, or is a single spherical shell, as on the moon, Mars, and Mercury. The evolution of a planetary lithosphere and the development of plate tectonics appear to be influenced by several factors, including planetary size, chemistry, and external and internal heat sources. Vertical tectonic movement due to lithospheric loading or uplift is similar on all of the terrestrial planets and is controlled by the local thickness and rheology of the lithosphere. The surface of Venus, although known only at low resolution, displays features both similar to those on Earth (mountain belts, high plateaus) and similar to those on the smaller planets (possible impact basins). Improved understanding of the tectonic evolution of Venus will permit an evaluation of the relative roles of planetary size and chemistry in determining evolutionary style.

  5. The Gemini Planet Imager

    SciTech Connect

    Macintosh, B; al., e

    2006-05-02

    The next major frontier in the study of extrasolar planets is direct imaging detection of the planets themselves. With high-order adaptive optics, careful system design, and advanced coronagraphy, it is possible for an AO system on a 8-m class telescope to achieve contrast levels of 10{sup -7} to 10{sup -8}, sufficient to detect warm self-luminous Jovian planets in the solar neighborhood. Such direct detection is sensitive to planets inaccessible to current radial-velocity surveys and allows spectral characterization of the planets, shedding light on planet formation and the structure of other solar systems. We have begun the construction of such a system for the Gemini Observatory. Dubbed the Gemini Planet Imager (GPI), this instrument should be deployed in 2010 on the Gemini South telescope. It combines a 2000-actuator MEMS-based AO system, an apodized-pupil Lyot coronagraph, a precision infrared interferometer for real-time wavefront calibration at the nanometer level, and a infrared integral field spectrograph for detection and characterization of the target planets. GPI will be able to achieve Strehl ratios > 0.9 at 1.65 microns and to observe a broad sample of science targets with I band magnitudes less than 8. In addition to planet detection, GPI will also be capable of polarimetric imaging of circumstellar dust disks, studies of evolved stars, and high-Strehl imaging spectroscopy of bright targets. We present here an overview of the GPI instrument design, an error budget highlighting key technological challenges, and models of the system performance.

  6. The planets and life.

    NASA Technical Reports Server (NTRS)

    Young, R. S.

    1971-01-01

    It is pointed out that planetary exploration is not simply a program designed to detect life on another planet. A planet similar to earth, such as Mars, when studied for evidence as to why life did not arise, may turn out to be scientifically more important than a planet which has already produced a living system. Of particular interest after Mars are Venus and Jupiter. Jupiter has a primitive atmosphere which may well be synthesizing organic molecules today. Speculations have been made concerning the possibility of a bio-zone in the upper atmosphere of Venus.

  7. Challenges in planet formation

    NASA Astrophysics Data System (ADS)

    Morbidelli, Alessandro; Raymond, Sean N.

    2016-10-01

    Over the past two decades, large strides have been made in the field of planet formation. Yet fundamental questions remain. Here we review our state of understanding of five fundamental bottlenecks in planet formation. These are the following: (1) the structure and evolution of protoplanetary disks; (2) the growth of the first planetesimals; (3) orbital migration driven by interactions between protoplanets and gaseous disk; (4) the origin of the Solar System's orbital architecture; and (5) the relationship between observed super-Earths and our own terrestrial planets. Given our lack of understanding of these issues, even the most successful formation models remain on shaky ground.

  8. The planets and life.

    NASA Technical Reports Server (NTRS)

    Young, R. S.

    1971-01-01

    It is pointed out that planetary exploration is not simply a program designed to detect life on another planet. A planet similar to earth, such as Mars, when studied for evidence as to why life did not arise, may turn out to be scientifically more important than a planet which has already produced a living system. Of particular interest after Mars are Venus and Jupiter. Jupiter has a primitive atmosphere which may well be synthesizing organic molecules today. Speculations have been made concerning the possibility of a bio-zone in the upper atmosphere of Venus.

  9. Minor Planet Center

    NASA Technical Reports Server (NTRS)

    Marsden, Brian G.

    1999-01-01

    This paper reports on the activities of the Minor Planet Center for the year of 1998. The main product of this center is the Minor Planet Circulars, augmented by the Minor Planet Circulars Supplement which is a new series introduced in 1997 to include the actual observations, which are now only summarized MPC. The introduction of the Daily Orbit Update (DOU) lists all the orbits computed and identification found since the previous issue. There has been a fivefold increase in the reported Near Earth Objects, which includes the addition of 55 potentially hazardous asteroids.

  10. From Disks to Planets

    NASA Astrophysics Data System (ADS)

    Youdin, Andrew N.; Kenyon, Scott J.

    This pedagogical chapter covers the theory of planet formation, with an emphasis on the physical processes relevant to current research. After summarizing empirical constraints from astronomical and geophysical data, we describe the structure and evolution of protoplanetary disks. We consider the growth of planetesimals and of larger solid protoplanets, followed by the accretion of planetary atmospheres, including the core accretion instability. We also examine the possibility that gas disks fragment directly into giant planets and/or brown dwarfs. We defer a detailed description of planet migration and dynamical evolution to other work, such as the complementary chapter in this series by Morbidelli.

  11. Planets under pressure

    NASA Astrophysics Data System (ADS)

    Jeanloz, Raymond

    2009-04-01

    Deep inside the planet Jupiter, diamonds hail down from hydrocarbon clouds as intense atmospheric pressures break methane into its atomic components. Further in - but still only 15% of the way to the planet's centre - the pressure reaches a million times that of the Earth's atmosphere. This is enough to transform hydrogen from the transparent, insulating gas we know at our planet's surface into a metallic fluid that sustains Jupiter's huge magnetic field. Even diamond is not forever: at pressures of 8-10 million atmospheres it is transformed into an opaque, metallic form of carbon, rather than the familiar transparent crystal.

  12. Our Changing Planet

    DTIC Science & Technology

    2003-01-01

    2003 2. REPORT TYPE 3. DATES COVERED 00-00-2003 to 00-00-2003 4. TITLE AND SUBTITLE Our Changing Planet 5a. CONTRACT NUMBER 5b. GRANT NUMBER...Budget Erin Wuchte Office of Management and Budget Margaret R. McCalla Office of the Federal Coordinator for Meteorology OUR CHANGING PLANET THE FISCAL...you a copy of Our Changing Planet : The FY 2003 U.S. Global Change Research Program and Climate Change Research Initiative. The report describes the

  13. Impact Vaporization as a Possible Source of Mercury's Calcium Exosphere

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.; Hahn, Joseph M.

    2015-01-01

    Mercury's calcium exosphere varies in a periodic way with that planet's true anomaly. We show that this pattern can be explained by impact vaporization from interplanetary dust with variations being due to Mercury's radial and vertical excursions through an interplanetary dust disk having an inclination within 5 degrees of the plane of Mercury's orbit. Both a highly inclined dust disk and a two-disk model (where the two disks have a mutual inclination) fail to reproduce the observed variation in calcium exospheric abundance with Mercury true anomaly angle. However, an additional source of impacting dust beyond the nominal dust disk is required near Mercury's true anomaly (?) 25deg +/-5deg. This is close to but not coincident with Mercury's true anomaly (?=45deg) when it crosses comet 2P/Encke's present day orbital plane. Interestingly, the Taurid meteor storms at Earth, which are also due to Comet Encke, are observed to occur when Earth's true anomaly is +/-20 or so degrees before and after the position where Earth and Encke orbital planes cross. The lack of exact correspondence with the present day orbit of Encke may indicate the width of the potential stream along Mercury's orbit or a previous cometary orbit. The extreme energy of the escaping calcium, estimated to have a temperature greater than 50000 K if the source is thermal, cannot be due to the impact process itself but must be imparted by an additional mechanism such as dissociation of a calcium-bearing molecule or ionization followed by recombination.

  14. The shape of Mercury's south-polar region

    NASA Astrophysics Data System (ADS)

    Perry, M. E.; Kahan, D. S.; Barnouin, O. S.; Ernst, C. M.; Solomon, S. C.; Zuber, M. T.; Smith, D. E.; Phillips, R. J.; Hauck, S. A.; Lemoine, F. G.; Neumann, G. A.; Peale, S. J.; Margot, J.; Mazarico, E.; McNutt, R. L.

    2011-12-01

    We present measurements of the radius of Mercury over the planet's southern hemisphere within 30° of the south pole. These measurements, derived from occultations of MESSENGER's radio frequency (RF) transmissions, are the first such measurements southward of 30°S, a region beyond the reach of the Mercury Laser Altimeter (MLA). The occultation start and end times, recovered with 0.3-s accuracy or better by fitting edge-diffraction patterns to the RF power history, are used to estimate Mercury's radius at the tangent point of the RF path. The occultation-analysis techniques were calibrated by comparing hundreds of occultation-derived radii to MLA measurements in Mercury's northern hemisphere, indicating a measurement accuracy of 0.4 km (one standard deviation). The southern-hemisphere data provide initial estimates of the flattening of the south-pole region and the north-south offset between Mercury's center of figure (COF) and center of mass (COM). A high degree of flattening would complement the north-polar depression and may indicate a rotationally driven equatorial bulge as the source for the degree-2 shape of Mercury. Alternatively, the lack of south-pole flattening would suggest that the north-pole depression may be a remnant of impacts or mantle convective flow. The presence or lack of a north-south COM-COF offset contributes to our understanding of the processes that shape Mercury's rotational and interior dynamics.

  15. Making an Iron Planet: The Case for Repeated Hit and Run Collisions

    NASA Astrophysics Data System (ADS)

    Asphaug, E. I.; Reufer, A.

    2014-12-01

    Earth, Venus, Mars and some of the largest asteroids have massive silicate mantles surrounding iron cores, and chondritic compositions. Against this backdrop are anomalies like the iron planet Mercury, and the Moon with almost no core, and metallic asteroids like Psyche. The Moon can be explained by giant impact, but for Mercury a giant impact (Benz et al., Icarus 1988) is problematic. Mercury must retain substantial volatiles after its obliteration (e.g. Peplowski et al., Science 2011), and must somehow avoid accreting its ejected silicates (Gladman and Coffey, MAPS 2009). SPH simulations have shown (Asphaug and Reufer, Nature Geosciences 2014; Sarid et al., LPSC 2014) that a differentiated chondritic proto-Mercury about 3 times its present mass can be stripped of its mantle in one energetic hit and run collision with a larger planet (proto-Venus or proto-Earth). To preserve Mercury's volatiles we also consider the scenario of lower energy hit and runs, in succession. We show that if 20 Mars-like planets accreted stochastically to form Venus and the Earth, then the statistics of attrition is likely to lead to one planet (Mercury) expressing repeated mantle stripping, and another planet (Mars) relatively undisturbed. For iron asteroids the "missing mantle paradox" likewise looms prominent. Where does it go, and how do we strip away so much mantle rock (in some cases down to a bare iron core; Yang et al., Nature 2007, Moskovitz et al., EPSL 2011) while leaving asteroids like Vesta presumably intact? According to the hit and run hypothesis, the sink for all this missing silicate is the larger accreted bodies at the top of the feeding chain, as they win the pairwise dynamical competition for stripped materials. This exotic origin of relics is only relevant to those few pairwise encounters that do not accrete both bodies. So the small survivors are lucky, and how they are lucky -- their attrition bias -- is manifested as compositional diversity and a preponderance of

  16. The Obliquities of the Giant Planets

    NASA Astrophysics Data System (ADS)

    Hamilton, D. P.; Ward, Wm. R.

    2002-09-01

    Jupiter has by far the smallest obliquity ( ~ 3o) of the planets (not counting tidally de-spun Mercury and Venus) which may be reflective of its formation by hydrodynamic gas flow rather than stochastic impacts. Saturn's obliquity ( ~ 26o), however, seems to belie this simple formation picture. But since the spin angular momentum of any planet is much smaller than its orbital angular momentum, post-formation obliquity can be strongly modified by passing through secular spin-orbit resonances, i.e., when the spin axis precession rate of the planet matches one of the frequencies describing the precession of the orbit plane. Spin axis precession is due to the solar torque on both the oblate figure of the planet and any orbiting satellites. In the case of Jupiter, the torque on the Galilean satellites is the principal cause of its 4.5*105 year precession; Saturn's precession of 1.8*106 years is dominated by Titan. In the past, the planetary spin axis precession rates should have been much faster due to the massive circumplanetary disks from which the current satellites condensed. The regression of the orbital node of a planet is due to the gravitational perturbations of the other planets. Nodal regression is not uniform, but is instead a composite of the planetary system's normal modes. For Jupiter and Saturn, the principal frequency is the nu16, with a period of ~ 49,000 years; the amplitude of this term is I ~ 0o.36 for Jupiter and I ~ 0o.90 for Saturn. In spite of the small amplitudes, slow adiabatic passages through this resonance (due to circumplanetary disk dispersal) could increase planetary obliquities from near zero to ~ [tan1/3 I] ~ 10o. We will discuss scenarios in which giant planet obliquities are affected by this and other resonances, and will use Jupiter's low obliquity to constrain the mass and duration of a satellite precursor disk. DPH acknowledges support from NSF Career Grant AST 9733789 and WRW is grateful to the NASA OSS and PGG programs.

  17. The evolution of the moon and the terrestrial planets

    NASA Technical Reports Server (NTRS)

    Toksoez, M. N.; Johnston, D. H.

    1974-01-01

    The thermal evolutions of the Moon, Mars, Venus and Mercury are calculated theoretically starting from cosmochemical condensation models. An assortment of geological, geochemical and geophysical data are used to constrain both the present day temperatures and the thermal histories of the planets' interiors. Such data imply that the planets were heated during or shortly after formation and that all the terrestrial planets started their differentiations early in their history. The moon, smallest in size, is characterized as a differentiated body with a crust, a thick solid mantle and an interior region which may be partially molten. Mars, intermediate in size, is assumed to have differentiated an Fe-FeS core. Venus is characterized as a planet not unlike the earth in many respects. Core formation has occurred probably during the first billion years after the formation. Mercury, which probably has a large core, may have a 500 km thick solid lithosphere and a partially molten core if it is assumed that some heat sources exist in the core.

  18. Observations of Mercury's magnetic field

    NASA Technical Reports Server (NTRS)

    Ness, N. F.; Behannon, K. W.; Lepping, R. P.; Whang, Y. C.

    1975-01-01

    Magnetic field data obtained by Mariner 10 during the third and final encounter with the planet Mercury on 16 March 1975 were studied. A well developed bow shock and modest magnetosphere, previously observed at first encounter on 29 March 1974, were again observed. In addition, a much stronger magnetic field near closest approach, 400 gamma versus 98 gamma, was observed at an altitude of 327 km and approximately 70 deg north Mercurian latitude. Spherical harmonic analysis of the data provide an estimate of the centered planetary magnetic dipole of 4.7 x 10 to the 22nd power Gauss/cu cm with the axis tilted 12 deg to the rotation axis and in the same sense as Earth's. The interplanetary field was sufficiently different between first and third encounters that in addition to the very large field magnitude observed, it argues strongly against a complex induction process generating the observed planetary field. While a possibility exists that Mercury possesses a remanent field due to magnetization early in its formation, a present day active dynamo seems to be a more likely candidate for its origin.

  19. [Chronic occupational metallic mercurialism].

    PubMed

    Faria, Marcília de Araújo Medrado

    2003-02-01

    This is a review on current knowledge of chronic occupational mercurialism syndrome. Major scientific studies and reviews on clinical manifestation and physiopathology of mercury poisoning were evaluated. The search was complemented using Medline and Lilacs data. Erethism or neuropsychological syndrome, characterized by irritability, personality change, loss of self-confidence, depression, delirium, insomnia, apathy, loss of memory, headaches, general pain, and tremors, is seen after exposure to metallic mercury. Hypertension, renal disturbances, allergies and immunological conditions are also common. Mercury is found in many different work processes: industries, gold mining, and dentistry. As prevention measures are not often adopted there is an increasing risk of mercury poisoning. The disease has been under diagnosed even though 16 clinical forms of mercury poisoning are described by Brazilian regulations. Clinical diagnosis is important, especially because abnormalities in the central nervous, renal and immunological systems can be detected using current medical technology, helping to develop the knowledge and control measures for mercurialism.

  20. Statistical analysis of micrometeoroids flux on Mercury

    NASA Astrophysics Data System (ADS)

    Borin, P.; Cremonese, G.; Marzari, F.; Bruno, M.; Marchi, S.

    2009-08-01

    Context: Meteoroid impacts are an important source of neutral atoms in the exosphere of Mercury. Impacting particles of size smaller than 1 cm have been proposed to be the major contribution to exospheric gases. However, our knowledge of the fluxes and impact velocities of different sizes is based on old extrapolations of similar quantities on Earth. Aims: We compute by means of N-body numerical integrations the orbital evolution of a large number of dust particles supposedly produced in the Main Belt. They migrate inward under the effect of drag forces until they encounter a terrestrial planet or eventually fall into the Sun. From our numerical simulations, we compute the flux of particles hitting Mercury's surface and the corresponding distribution of impact velocities. Methods: The orbital evolution of dust particles of different sizes is computed with a numerical code based on a physical model developed previously by Marzari & Vanzani (1994, A&A, 283, 275). It includes the effects of Poynting-Robertson drag, solar wind drag, and planetary perturbations. A precise calibration of the particle flux on Mercury has been performed by comparing our model predictions for dust infall on to Earth with observational data. Results: We provide predictions of the flux to different size particles impacting Mercury and their collisional velocity distribution. We compare our results with previous estimates and we find that these collisional velocities are lower but that the fluxes are significantly higher.

  1. Silicate mineralogy at the surface of Mercury

    NASA Astrophysics Data System (ADS)

    Namur, Olivier; Charlier, Bernard

    2017-01-01

    NASA's MESSENGER spacecraft has revealed geochemical diversity across Mercury's volcanic crust. Near-infrared to ultraviolet spectra and images have provided evidence for the Fe2+-poor nature of silicate minerals, magnesium sulfide minerals in hollows and a darkening component attributed to graphite, but existing spectral data is insufficient to build a mineralogical map for the planet. Here we investigate the mineralogical variability of silicates in Mercury's crust using crystallization experiments on magmas with compositions and under reducing conditions expected for Mercury. We find a common crystallization sequence consisting of olivine, plagioclase, pyroxenes and tridymite for all magmas tested. Depending on the cooling rate, we suggest that lavas on Mercury are either fully crystallized or made of a glassy matrix with phenocrysts. Combining the experimental results with geochemical mapping, we can identify several mineralogical provinces: the Northern Volcanic Plains and Smooth Plains, dominated by plagioclase, the High-Mg province, strongly dominated by forsterite, and the Intermediate Plains, comprised of forsterite, plagioclase and enstatite. This implies a temporal evolution of the mineralogy from the oldest lavas, dominated by mafic minerals, to the youngest lavas, dominated by plagioclase, consistent with progressive shallowing and decreasing degree of mantle melting over time.

  2. Discovery of calcium in Mercury's atmosphere.

    PubMed

    Bida, T A; Killen, R M; Morgan, T H

    2000-03-09

    The composition and evolutionary history of Mercury's crust are not well determined. The planet as a whole has been predicted to have a refractory, anhydrous composition: rich in Ca, Al, Mg and Fe, but poor in Na, K, OH, and S. Its atmosphere is believed to be derived in large part from the surface materials. A combination of effects that include impact vaporization (from infalling material), volatile evaporation, photon-stimulated desorption and sputtering releases material from the surface to form the atmosphere. Sodium and potassium have already been observed in Mercury's atmosphere, with abundances that require a volatile-rich crust. The sodium probably results from photon-stimulated desorption, and has a temperature of 1,500 K (ref. 10). Here we report the discovery of calcium in the atmosphere near Mercury's poles. The column density is very low and the temperature is apparently very high (12,000 K). The localized distribution and high temperature, if confirmed, suggest that the atmospheric calcium may arise from surface sputtering by ions, which enter Mercury's auroral zone. The low abundance of atmospheric Ca may indicate that the regolith is rarefied in calcium.

  3. The Antarctic Planet Interferometer

    NASA Technical Reports Server (NTRS)

    Swain, Mark R.; Walker, Christopher K.; Traub, Wesley A.; Storey, John W.; CoudeduForesto, Vincent; Fossat, Eric; Vakili, Farrok; Stark, Anthony A.; Lloyd, James P.; Lawson, Peter R.; hide

    2004-01-01

    The Antarctic Planet Interferometer is an instrument concept designed to detect and characterize extrasolar planets by exploiting the unique potential of the best accessible site on earth for thermal infrared interferometry. High-precision interferometric techniques under development for extrasolar planet detection and characterization (differential phase, nulling and astrometry) all benefit substantially from the slow, low-altitude turbulence, low water vapor content, and low temperature found on the Antarctic plateau. At the best of these locations, such as the Concordia base being developed at Dome C, an interferometer with two-meter diameter class apertures has the potential to deliver unique science for a variety of topics, including extrasolar planets, active galactic nuclei, young stellar objects, and protoplanetary disks.

  4. Managing Planet Earth.

    ERIC Educational Resources Information Center

    Clark, William C.

    1989-01-01

    Discusses the human use of the planet earth. Describes the global patterns and the regional aspects of change. Four requirements for the cultivation of leadership and institutional competence are suggested. Lists five references for further reading. (YP)

  5. Tenth Planet Discovered

    NASA Image and Video Library

    2005-08-03

    These time-lapse images of a newfound dwarf planet in our solar system, formerly known as 2003 UB313 or Xena, and now called Eris, were taken using the Samuel Oschin Telescope at the Palomar Observatory.

  6. Moon Shadow, Planet Shadow

    NASA Image and Video Library

    2010-05-12

    Saturn moon Prometheus casts a narrow shadow on the rings near the much larger shadow cast by the planet in this image taken by NASA Cassini spacecraft about five months after Saturn August 2009 equinox.

  7. Kepler's Multiple Planet Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2012-01-01

    Among the 1800 Kepler targets that have candidate planets, 20% have two or more candidate planets. While most of these objects have not yet been confirmed as true planets, several considerations strongly suggest that the vast majority of these multi-candidate systems are true planetary systems. Virtually all candidate systems are stable, as tested by numerical integrations (assuming a nominal mass-radius relationship). Statistical studies performed on these candidates reveal a great deal about the architecture of planetary systems, including the typical spacing of orbits and flatness of planetary systems. The distribution of observed period ratios shows that the vast majority of candidate pairs are neither in nor near low-order mean motion resonances. Nonetheless, there are small but statistically significant excesses of candidate pairs both in resonance and spaced slightly too far apart to be in resonance, particularly near the 2:1 resonance. The characteristics of the confirmed Kepler multi-planet systems will also be discussed.

  8. Magnetic Mystery Planets

    NASA Astrophysics Data System (ADS)

    Fillingim, M. O.; Brain, D. A.; Peticolas, L. M.; Yan, D.; Fricke, K. W.; Thrall, L.

    2013-12-01

    The magnetic fields of the large terrestrial planets, Venus, Earth, and Mars, are all vastly different from each other. These differences can tell us a lot about the interior structure, interior history, and even give us clues to the atmospheric history of these planets. This presentation highlights a classroom presentation and accompanying activity that focuses on the differences between the magnetic fields of Venus, Earth, and Mars, what these differences mean, and how we measure these differences. During the activity, students make magnetic field measurements and draw magnetic field lines around "mystery planets" using orbiting "spacecraft" (small compasses). Based on their observations, the students then determine whether they are orbiting Venus-like, Earth-like, or Mars-like planets. This activity is targeted to middle/high school age audiences. However, we also show a scaled-down version that has been used with elementary school age audiences.

  9. Planets Around Neutron Stars

    NASA Technical Reports Server (NTRS)

    Wolszczan, Alexander; Kulkarni, Shrinivas R; Anderson, Stuart B.

    2003-01-01

    The objective of this proposal was to continue investigations of neutron star planetary systems in an effort to describe and understand their origin, orbital dynamics, basic physical properties and their relationship to planets around normal stars. This research represents an important element of the process of constraining the physics of planet formation around various types of stars. The research goals of this project included long-term timing measurements of the planets pulsar, PSR B1257+12, to search for more planets around it and to study the dynamics of the whole system, and sensitive searches for millisecond pulsars to detect further examples of old, rapidly spinning neutron stars with planetary systems. The instrumentation used in our project included the 305-m Arecibo antenna with the Penn State Pulsar Machine (PSPM), the 100-m Green Bank Telescope with the Berkeley- Caltech Pulsar Machine (BCPM), and the 100-m Effelsberg and 64-m Parkes telescopes equipped with the observatory supplied backend hardware.

  10. Students Discover Unique Planet

    NASA Astrophysics Data System (ADS)

    2008-12-01

    Three undergraduate students, from Leiden University in the Netherlands, have discovered an extrasolar planet. The extraordinary find, which turned up during their research project, is about five times as massive as Jupiter. This is also the first planet discovered orbiting a fast-rotating hot star. Omega Centauri ESO PR Photo 45a/08 A planet around a hot star The students were testing a method of investigating the light fluctuations of thousands of stars in the OGLE database in an automated way. The brightness of one of the stars was found to decrease for two hours every 2.5 days by about one percent. Follow-up observations, taken with ESO's Very Large Telescope in Chile, confirmed that this phenomenon is caused by a planet passing in front of the star, blocking part of the starlight at regular intervals. According to Ignas Snellen, supervisor of the research project, the discovery was a complete surprise. "The project was actually meant to teach the students how to develop search algorithms. But they did so well that there was time to test their algorithm on a so far unexplored database. At some point they came into my office and showed me this light curve. I was completely taken aback!" The students, Meta de Hoon, Remco van der Burg, and Francis Vuijsje, are very enthusiastic. "It is exciting not just to find a planet, but to find one as unusual as this one; it turns out to be the first planet discovered around a fast rotating star, and it's also the hottest star found with a planet," says Meta. "The computer needed more than a thousand hours to do all the calculations," continues Remco. The planet is given the prosaic name OGLE2-TR-L9b. "But amongst ourselves we call it ReMeFra-1, after Remco, Meta, and myself," says Francis. The planet was discovered by looking at the brightness variations of about 15 700 stars, which had been observed by the OGLE survey once or twice per night for about four years between 1997 and 2000. Because the data had been made public

  11. 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

  12. Fast spin of the young extrasolar planet β Pictoris b

    NASA Astrophysics Data System (ADS)

    Snellen, Ignas A. G.; Brandl, Bernhard R.; de Kok, Remco J.; Brogi, Matteo; Birkby, Jayne; Schwarz, Henriette

    2014-05-01

    The spin of a planet arises from the accretion of angular momentum during its formation, but the details of this process are still unclear. In the Solar System, the equatorial rotation velocities and, consequently, spin angular momenta of most of the planets increase with planetary mass; the exceptions to this trend are Mercury and Venus, which, since formation, have significantly spun down because of tidal interactions. Here we report near-infrared spectroscopic observations, at a resolving power of 100,000, of the young extrasolar gas giant planet β Pictoris b (refs 7, 8). The absorption signal from carbon monoxide in the planet's thermal spectrum is found to be blueshifted with respect to that from the parent star by approximately 15 kilometres per second, consistent with a circular orbit. The combined line profile exhibits a rotational broadening of about 25 kilometres per second, meaning that β Pictoris b spins significantly faster than any planet in the Solar System, in line with the extrapolation of the known trend in spin velocity with planet mass.

  13. Outer planet satellites

    SciTech Connect

    Schenk, P.M. )

    1991-01-01

    Recent findings on the outer-planet satellites are presented, with special consideration given to data on the rheologic properties of ice on icy satellites, the satellite surfaces and exogenic processes, cratering on dead cratered satellites, volcanism, and the interiors of outer-planet satellites. Particular attention is given to the state of Titan's surface and the properties of Triton, Pluto, and Charon. 210 refs.

  14. Transit of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Doyle, Laurance R.

    1998-01-01

    During the past five years we have pursued the detection of extrasolar planets by the photometric transit method, i.e. the detection of a planet by watching for a drop in the brightness of the light as it crosses in front of a star. The planetary orbit must cross the line-of-sight and so most systems will not be lined up for such a transit to ever occur. However, we have looked at eclipsing binary systems which are already edge-on. Such systems must be very small in size as this makes the differential light change due to a transit much greater for a given planet size (the brightness difference will be proportional to the area of the transiting planet to the disc area of the star). Also, the planet forming region should be closer to the star as small stars are generally less luminous (that is, if the same thermal regime for planet formation applies as in the solar system). This led to studies of the habitable zone around other stars, as well. Finally, we discovered that our data could be used to detect giant planets without transits as we had been carefully timing the eclipses of the stars (using a GPS antenna for time) and this will drift by being offset by any giant planets orbiting around the system, as well. The best summary of our work may be to just summarize the 21 refereed papers produced during the time of this grant. This will be done is chronological order and in each section separately.

  15. The planet Saturn (1970)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The present-day knowledge on Saturn and its environment are described for designers of spacecraft which are to encounter and investigate the planet. The discussion includes physical properties of the planet, gravitational field, magnetic and electric fields, electromagnetic radiation, satellites and meteoroids, the ring system, charged particles, atmospheric composition and structure, and clouds and atmospheric motions. The environmental factors which have pertinence to spacecraft design criteria are also discussed.

  16. Planning Bepicolombo MPO Science Operations to study Mercury Interior

    NASA Astrophysics Data System (ADS)

    De La Fuente, Sara; Carasa, Angela; Ortiz, Iñaki; Rodriguez, Pedro; Casale, Mauro; Benkhoff, Johannes; Zender, Joe

    2017-04-01

    BepiColombo is an Interdisciplinary Cornerstone ESA-JAXA Mission to Mercury, with two orbiters, the ESA Mercury Planetary Orbiter (MPO) and the JAXA Mercury Magnetospheric Orbiter (MMO) dedicated to study of the planet and its magnetosphere. The MPO, is a three-axis-stabilized, nadir-pointing spacecraft which will be placed in a polar orbit, providing excellent spatial resolution over the entire planet surface. The MPO's scientific payload comprises 11 instrument packages, including laser altimeter, cameras and the radio science experiment that will be dedicated to the study of Mercury's interior: structure, composition, formation and evolution. The planning of the science operations to be carried out by the Mercury's interior scientific instruments will be done by the SGS located at the European Space Astronomy Centre (ESAC), in conjunction with the scientific instrument teams. The process will always consider the complete nominal mission duration, such that the contribution of the scheduled science operations to the science objectives, the total data volume generated, and the seasonal interdependency, can be tracked. The heart of the science operations planning process is the Observations Catalogue (OC), a web-accessed database to collect and analyse all science operations requests. From the OC, the SGS will first determine all science opportunity windows compatible with the spacecraft operational constraints. Secondly, only those compatible with the resources (power and data volume) and pointing constraints will be chosen, including slew feasibility.

  17. Does Mercury have a molten core

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    1976-01-01

    A feasible nonseismic observational experiment is proposed for determining the existence and extent of a conducting molten core within Mercury. This experiment would utilize the effects of a liquid core on the dynamics of Mercury's rotation; two necessary conditions for performing it are that the core must not follow the mantle's forced librations in longitude but must follow the mantle on the timescale of the 250,000-yr precession. A method is developed by assuming these conditions to be satisfied, and bounds are established on the core viscosity for which they are satisfied. It is shown that the value of the ratio of the moment of inertia of the mantle to the largest principal moment of inertia of the entire planet would indicate whether the core is most probably solid, partially fluid, or entirely fluid. Techniques are suggested for determining the unknowns required to compute the necessary ratio.

  18. Building a virtual planet

    NASA Technical Reports Server (NTRS)

    Meadows, V. S.

    2002-01-01

    The virtual Planetary Laboratory (VPL) is a recently funded 5-yr project, which seeks toimprove our understanding of the range of plausible environments and the likely signatures for life on extrasolar terrestrial planets. To achieve these goals we are developing a suite of innovative modeling tools to simulate the environments and spectra of extrasolar planets. The core of the VPL IS a coupled radiative transfer/climate/chemistry model, which is augmented by interchangeable modules which characterize geological, exogenic, atmospheric escape, and life processes. The VPL is validated using data derived from terrestrial planets within our own solar system. The VPL will be used to explore the plausible range of atmospheric composittions and globally averaged spectra for extrasolar planets and for early Earth, and will improve our understanding of the effect of life on a planet's atmospheric spectrum and composition. The models will also be used to create a comprehensive spectral catalog to provide recommendations on the optimum wavelength range, spectral resolution, and instrument sensitivity required to characterize extrasolar terrestrial planets. Although developed by our team, the VPL is envisioned to be a comprehensive and flexible tool, which can be collaboratively used by the broader planetary science and astrobiology communities. This presentation will describe the project concept, the tasks involved, and will outline current progress to date. This work is funded by the NASA Astrobiology Institute.

  19. Building a virtual planet

    NASA Technical Reports Server (NTRS)

    Meadows, V. S.

    2002-01-01

    The virtual Planetary Laboratory (VPL) is a recently funded 5-yr project, which seeks toimprove our understanding of the range of plausible environments and the likely signatures for life on extrasolar terrestrial planets. To achieve these goals we are developing a suite of innovative modeling tools to simulate the environments and spectra of extrasolar planets. The core of the VPL IS a coupled radiative transfer/climate/chemistry model, which is augmented by interchangeable modules which characterize geological, exogenic, atmospheric escape, and life processes. The VPL is validated using data derived from terrestrial planets within our own solar system. The VPL will be used to explore the plausible range of atmospheric composittions and globally averaged spectra for extrasolar planets and for early Earth, and will improve our understanding of the effect of life on a planet's atmospheric spectrum and composition. The models will also be used to create a comprehensive spectral catalog to provide recommendations on the optimum wavelength range, spectral resolution, and instrument sensitivity required to characterize extrasolar terrestrial planets. Although developed by our team, the VPL is envisioned to be a comprehensive and flexible tool, which can be collaboratively used by the broader planetary science and astrobiology communities. This presentation will describe the project concept, the tasks involved, and will outline current progress to date. This work is funded by the NASA Astrobiology Institute.

  20. The Atmospheres of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Richardson, L. J.; Seager, S.

    2007-01-01

    In this chapter we examine what can be learned about extrasolar planet atmospheres by concentrating on a class of planets that transit their parent stars. As discussed in the previous chapter, one way of detecting an extrasolar planet is by observing the drop in stellar intensity as the planet passes in front of the star. A transit represents a special case in which the geometry of the planetary system is such that the planet s orbit is nearly edge-on as seen from Earth. As we will explore, the transiting planets provide opportunities for detailed follow-up observations that allow physical characterization of extrasolar planets, probing their bulk compositions and atmospheres.

  1. Mercury Report-Children's exposure to elemental mercury

    MedlinePlus

    ... PDF - 781KB] En Español [PDF - 6.6MB] What did ATSDR find? For children, most elemental mercury exposures ... that exposed children to elemental mercury. The report did not include a review of mercury exposures from ...

  2. Mercury Calibration System

    SciTech Connect

    John Schabron; Eric Kalberer; Joseph Rovani; Mark Sanderson; Ryan Boysen; William Schuster

    2009-03-11

    U.S. Environmental Protection Agency (EPA) Performance Specification 12 in the Clean Air Mercury Rule (CAMR) states that a mercury CEM must be calibrated with National Institute for Standards and Technology (NIST)-traceable standards. In early 2009, a NIST traceable standard for elemental mercury CEM calibration still does not exist. Despite the vacature of CAMR by a Federal appeals court in early 2008, a NIST traceable standard is still needed for whatever regulation is implemented in the future. Thermo Fisher is a major vendor providing complete integrated mercury continuous emissions monitoring (CEM) systems to the industry. WRI is participating with EPA, EPRI, NIST, and Thermo Fisher towards the development of the criteria that will be used in the traceability protocols to be issued by EPA. An initial draft of an elemental mercury calibration traceability protocol was distributed for comment to the participating research groups and vendors on a limited basis in early May 2007. In August 2007, EPA issued an interim traceability protocol for elemental mercury calibrators. Various working drafts of the new interim traceability protocols were distributed in late 2008 and early 2009 to participants in the Mercury Standards Working Committee project. The protocols include sections on qualification and certification. The qualification section describes in general terms tests that must be conducted by the calibrator vendors to demonstrate that their calibration equipment meets the minimum requirements to be established by EPA for use in CAMR monitoring. Variables to be examined include linearity, ambient temperature, back pressure, ambient pressure, line voltage, and effects of shipping. None of the procedures were described in detail in the draft interim documents; however they describe what EPA would like to eventually develop. WRI is providing the data and results to EPA for use in developing revised experimental procedures and realistic acceptance criteria based on

  3. MESSENGER observations of Mercury's exosphere: detection of magnesium and distribution of constituents.

    PubMed

    McClintock, William E; Vervack, Ronald J; Bradley, E Todd; Killen, Rosemary M; Mouawad, Nelly; Sprague, Ann L; Burger, Matthew H; Solomon, Sean C; Izenberg, Noam R

    2009-05-01

    Mercury is surrounded by a tenuous exosphere that is supplied primarily by the planet's surface materials and is known to contain sodium, potassium, and calcium. Observations by the Mercury Atmospheric and Surface Composition Spectrometer during MESSENGER's second Mercury flyby revealed the presence of neutral magnesium in the tail (anti-sunward) region of the exosphere, as well as differing spatial distributions of magnesium, calcium, and sodium atoms in both the tail and the nightside, near-planet exosphere. Analysis of these observations, supplemented by observations during the first Mercury flyby, as well as those by other MESSENGER instruments, suggests that the distinct spatial distributions arise from a combination of differences in source, transfer, and loss processes.

  4. An Assessment of the Length and Variability of Mercury's Magnetotail

    NASA Technical Reports Server (NTRS)

    Milan, S. E.; Slavin, J. A.

    2011-01-01

    We employ Mariner 10 measurements of the interplanetary magnetic field in the vicinity of Mercury to estimate the rate of magnetic reconnection between the interplanetary magnetic field and the Hermean magnetosphere. We derive a time-series of the open magnetic flux in Mercury's magnetosphere. from which we can deduce the length of the magnetotail The length of the magnetotail is shown to be highly variable. with open field lines stretching between 15R(sub H) and 8S0R(sub H) downstream of the planet (median 150R(sub H)). Scaling laws allow the tail length at perihelion to be deduced from the aphelion Mariner 10 observations.

  5. An Assessment of the Length and Variability of Mercury's Magnetotail

    NASA Technical Reports Server (NTRS)

    Milan, S. E.; Slavin, J. A.

    2011-01-01

    We employ Mariner 10 measurements of the interplanetary magnetic field in the vicinity of Mercury to estimate the rate of magnetic reconnection between the interplanetary magnetic field and the Hermean magnetosphere. We derive a time-series of the open magnetic flux in Mercury's magnetosphere. from which we can deduce the length of the magnetotail The length of the magnetotail is shown to be highly variable. with open field lines stretching between 15R(sub H) and 8S0R(sub H) downstream of the planet (median 150R(sub H)). Scaling laws allow the tail length at perihelion to be deduced from the aphelion Mariner 10 observations.

  6. Underlying Architecture of Planetary Systems Based on Kepler Data: Number of Planets and Coplanarity

    NASA Astrophysics Data System (ADS)

    Fang, Julia; Margot, J. L.

    2012-10-01

    We investigated the underlying architecture of planetary systems by deriving the distribution of planet multiplicity (number of planets) and the distribution of orbital inclinations based on the sample of planet candidates discovered by the Kepler mission. The scope of our study included solar-like stars and planets with orbital periods less than 200 days and with radii between 1.5 and 30 Earth radii, and was based on Kepler planet candidates detected during Quarters 1 through 6. Our analysis improves on previous work by including all available quarters, extending to 200-day periods, and fitting models to observables such as normalized transit duration ratios that contain information on mutual orbital inclinations; these improvements lend to a deeper investigation of the intrinsic distributions of planetary systems. We created models of planetary systems with different distributions of planet multiplicity and orbital inclinations, simulated observations of these systems by Kepler, and compared the number and properties of the transits of detectable objects to actual Kepler planet detections. Based on the underlying distributions of our best-fit models, 75-80% of planetary systems have 1 or 2 planets with orbital periods less than 200 days. In addition, over 85% of planets have orbital inclinations less than 3 degrees. This high degree of coplanarity is comparable to that seen in our Solar System, with the exception of Mercury. These results provide important constraints and insights into theories of planet formation and evolution.

  7. New concepts for Mercury orbiter missions

    NASA Technical Reports Server (NTRS)

    French, J. R.; Stuart, J. R.; Zeldin, B.

    1978-01-01

    The next logical step in the exploration of Mercury is an orbiter mission. A conflict exists between those in the field of planetary sciences who desire a mission with a low circular orbit, and scientists in the fields and particles disciplines, who generally prefer a highly elliptical spacecraft orbit. The thermal environment imposed by the sun and planet render the low orbit intolerable for spacecraft using previous thermal control methods. A thermal control concept and a spacecraft mission concept have been developed which resolve these problems and promise a scientifically significant mission for the mid-1980s.

  8. Mercury: The World Closest to the Sun.

    ERIC Educational Resources Information Center

    Cordell, Bruce M.

    1984-01-01

    Discusses various topics related to the geology of Mercury including the origin of Mercury's magnetism, Mercury's motions, volcanism, scarps, and Mercury's violent birth and early life. Includes a table comparing Mercury's orbital and physical data to that of earth's. (JN)

  9. Mercury: The World Closest to the Sun.

    ERIC Educational Resources Information Center

    Cordell, Bruce M.

    1984-01-01

    Discusses various topics related to the geology of Mercury including the origin of Mercury's magnetism, Mercury's motions, volcanism, scarps, and Mercury's violent birth and early life. Includes a table comparing Mercury's orbital and physical data to that of earth's. (JN)

  10. Reinflating Giant Planets

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-01-01

    Two new, large gas-giant exoplanets have been discovered orbiting close to their host stars. A recent study examining these planets and others like them may help us to better understand what happens to close-in hot Jupiters as their host stars reach the end of their main-sequence lives.OversizedGiantsUnbinned transit light curves for HAT-P-65b. [Adapted from Hartman et al. 2016]The discovery of HAT-P-65b and HAT-P-66b, two new transiting hot Jupiters, is intriguing. These planets have periods of just under 3 days and masses of roughly 0.5 and 0.8 times that of Jupiter, but their sizes are whats really interesting: they have inflated radii of 1.89 and 1.59 times that of Jupiter.These two planets, discovered using the Hungarian-made Automated Telescope Network (HATNet) in Arizona and Hawaii, mark the latest in an ever-growing sample of gas-giant exoplanets with radii larger than expected based on theoretical planetary structure models.What causes this discrepancy? Did the planets just fail to contract to the expected size when they were initially formed, or were they reinflated later in their lifetimes? If the latter, how? These are questions that scientists are only now starting to be able to address using statistics of the sample of close-in, transiting planets.Unbinned transit light curves for HAT-P-66b. [Hartman et al. 2016]Exploring Other PlanetsLed by Joel Hartman (Princeton University), the team that discovered HAT-P-65b and HAT-P-66b has examined these planets observed parameters and those of dozens of other known close-in, transiting exoplanets discovered with a variety of transiting exoplanet missions: HAT, WASP, Kepler, TrES, and KELT. Hartman and collaborators used this sample to draw conclusions about what causes some of these planets to have such large radii.The team found that there is a statistically significant correlation between the radii of close-in giant planets and the fractional ages of their host stars (i.e., the stars age divided by its full

  11. Studies of outer planet satellites, Mercury and Uranus

    NASA Technical Reports Server (NTRS)

    Mckinnon, William B.; Schenk, Paul M.

    1987-01-01

    Arguments were made, based on geometry, for both an impact and an internal origin for the ancient, partially preserved furrow system of Ganymede. It was concluded that furrows were not concentric, but could be impact related if multiringed structures on icy satellites are initially noncircular. The geometry of the Valhalla ring structure on Callisto was examined in order to assess the circularity of an unmodified ring system. The Ganymede furrow system was remapped to make use of improvements in coordinate control. The least-squares center of curvature for all furrows in the Marius and Galileao Regio is -20.7, and 179.2 degrees. Furrows in Marius and Galileo Regio are reasonably concentric, and are much more circular than previously estimated. The perceived present nonalignment of the assumed originally concentric furrows were used to argue for large-scale lateral motion of dark terrain blocks in Ganymede's crust, presumably in association with bright terrain formation., The overall alignment of furrows as well as the inherent scatter in centers of curvature from subregions of Galileo and Marius do not support this hypothesis.

  12. Extrasolar binary planets. I. Formation by tidal capture during planet-planet scattering

    SciTech Connect

    Ochiai, H.; Nagasawa, M.; Ida, S.

    2014-08-01

    We have investigated (1) the formation of gravitationally bounded pairs of gas-giant planets (which we call 'binary planets') from capturing each other through planet-planet dynamical tide during their close encounters and (2) the subsequent long-term orbital evolution due to planet-planet and planet-star quasi-static tides. For the initial evolution in phase 1, we carried out N-body simulations of the systems consisting of three Jupiter-mass planets taking into account the dynamical tide. The formation rate of the binary planets is as much as 10% of the systems that undergo orbital crossing, and this fraction is almost independent of the initial stellarcentric semimajor axes of the planets, while ejection and merging rates sensitively depend on the semimajor axes. As a result of circularization by the planet-planet dynamical tide, typical binary separations are a few times the sum of the physical radii of the planets. After the orbital circularization, the evolution of the binary system is governed by long-term quasi-static tide. We analytically calculated the quasi-static tidal evolution in phase 2. The binary planets first enter the spin-orbit synchronous state by the planet-planet tide. The planet-star tide removes angular momentum of the binary motion, eventually resulting in a collision between the planets. However, we found that the binary planets survive the tidal decay for the main-sequence lifetime of solar-type stars (∼10 Gyr), if the binary planets are beyond ∼0.3 AU from the central stars. These results suggest that the binary planets can be detected by transit observations at ≳ 0.3 AU.

  13. Magnetism of Terrestrial Planets and Major Satellites

    NASA Astrophysics Data System (ADS)

    Spohn, T.; Breuer, D.

    of the terrestrial planets and major satellites Earth, Mercury, and Ganymede are known to have self-generated magnetic fields. Mars and Moon have remnantly mag- netized crust units that may have been magnetized early in their evolution, although alternative explanations exist. The magnetic properties of Venus are not very well known but any magnetic field must have a dipole moment smaller then 4 ×1018 Am2. The most recent data from the Galileo mission suggest that Io does not have a mag- netic field just as Europa and Callisto. Ganymede, however, has a field. Necessary conditions for dynamo actions in the cores of these bodies (assuming that all of them, except for Callisto, have iron-rich cores) are fluid motion driven either by thermal or chemical buoyancy. Freeze out of an inner core may release chemical buoyancy and drive a dynamo very effectively. Convection in the core, in turn, requires cooling of the core by the mantle at a sufficiently large rate. Recent models of mantle convection with temperature dependent viscosity have deepened our understanding of the cooling of the cores and allow a consistent model of the magnetic properties of the solid plan- ets and major satellites. The Earth's core is cooled efficiently by plate tectonics. The other planets and satellites lack plate tectonics and its efficient cooling mechanism. Rather, a one-plate stagnant lid, a thermal lithosphere, develops. The cooling of the mantle under these circumstances will occur mostly through the thickening of the lid while the deep mantle will cool comparatively little. The core will show some efficient cooling initially if it was superheated during core formation. But after about a billion year of core convection and magnetic field generation, the core will become stably stratified and the dynamo will cease to operate. With sufficient sulfur reducing the melting point temperature, the core will remain entirely liquid and chemical convec- tion will not be available as a driver of

  14. Process for low mercury coal

    DOEpatents

    Merriam, N.W.; Grimes, R.W.; Tweed, R.E.

    1995-04-04

    A process is described for producing low mercury coal during precombustion procedures by releasing mercury through discriminating mild heating that minimizes other burdensome constituents. Said mercury is recovered from the overhead gases by selective removal. 4 figures.

  15. Process for low mercury coal

    DOEpatents

    Merriam, Norman W.; Grimes, R. William; Tweed, Robert E.

    1995-01-01

    A process for producing low mercury coal during precombustion procedures by releasing mercury through discriminating mild heating that minimizes other burdensome constituents. Said mercury is recovered from the overhead gases by selective removal.

  16. Protostars and Planets VI

    NASA Astrophysics Data System (ADS)

    Beuther, Henrik; Klessen, Ralf S.; Dullemond, Cornelis P.; Henning, Thomas

    The Protostars and Planets book and conference series has been a long-standing tradition that commenced with the first meeting led by Tom Gehrels and held in Tucson, Arizona, in 1978. The goal then, as it still is today, was to bridge the gap between the fields of star and planet formation as well as the investigation of planetary systems and planets. As Tom Gehrels stated in the preface to the first Protostars and Planets book, "Cross-fertilization of information and understanding is bound to occur when investigators who are familiar with the stellar and interstellar phases meet with those who study the early phases of solar system formation." The central goal remained the same for the subsequent editions of the books and conferences Protostars and Planets II in 1984, Protostars and Planets III in 1990, Protostars and Planets IV in 1998, and Protostars and Planets V in 2005, but has now been greatly expanded by the flood of new discoveries in the field of exoplanet science. The original concept of the Protostars and Planets series also formed the basis for the sixth conference in the series, which took place on July 15-20, 2013. It was held for the first time outside of the United States in the bustling university town of Heidelberg, Germany. The meeting attracted 852 participants from 32 countries, and was centered around 38 review talks and more than 600 posters. The review talks were expanded to form the 38 chapters of this book, written by a total of 250 contributing authors. This Protostars and Planets volume reflects the current state-of-the-art in star and planet formation, and tightly connects the fields with each other. It is structured into four sections covering key aspects of molecular cloud and star formation, disk formation and evolution, planetary systems, and astrophysical conditions for life. All poster presentations from the conference can be found at www.ppvi.org. In the eight years that have passed since the fifth conference and book in the

  17. Laser altimetry of Mercury, Moon, and Mars

    NASA Astrophysics Data System (ADS)

    Neumann, G. A.; Mazarico, E.; Smith, D. E.; Zuber, M. T.; Torrence, M. H.; Barnouin, O. S.; Solomon, S. C.

    2011-12-01

    Since March 29 of this year, the Mercury Laser Altimeter (MLA) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has been ranging twice daily to the surface of Mercury from orbit, collecting more than 1 million ranges each month. Mercury joins Earth, Moon, and Mars as a planetary body mapped precisely by laser altimetry from orbit. Ranging covers nearly all of the northern hemisphere. The southern hemisphere largely lies beyond the 1800-km range of MLA from MESSENGER's eccentric orbit, but the 10-cm-precision MLA data will eventually be complemented by less precise radio occultation and limb profiling measurements by the MESSENGER spacecraft, as well as by digital topographic models produced by stereo photogrammetry. Mercury topography is distinguished from its larger and smaller counterparts by a relatively low (<10 km) dynamic range, less than half that of Earth, Moon, and Mars, and two-thirds that of its nearest neighbor, Venus. There are ample indications from the topography of Mercury impact structures as well as from its low-degree shape that Mercury's thermal evolution was complex and differed from those of other terrestrial planets. Central to the thermal history are the extensive contractional tectonic features for which altimetry quantifies accommodated strain. As well, MLA profiles of extensional graben within more than two dozen impact craters and basins, together with topographic and gravity field observations, will constrain the evolution of Mercury's upper crust and lithosphere. Lidar topographic data provide a wealth of geological contextual information regarding impact crater formation and modification, tectonics, volcanism, lithospheric strength, thermal evolution, and internal structure. Topography is essential for orthorectification of images and calibration of reflectance data. Geodetic topography, referenced to the center of mass, in conjunction with gravity, allows an assessment of the distribution of

  18. Gravity, Topography, and Magnetic Field of Mercury from Messenger

    NASA Technical Reports Server (NTRS)

    Neumann, Gregory A.; Solomon, Sean C.; Zuber, Maria T.; Phillips, Roger J.; Barnouin, Olivier; Ernst, Carolyn; Goosens, Sander; Hauck, Steven A., II; Head, James W., III; Johnson, Catherine L.; hide

    2012-01-01

    On 18 March 2011, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was inserted into a 12-hour, near-polar orbit around Mercury, with an initial periapsis altitude of 200 km, initial periapse latitude of 60 deg N, and apoapsis at approximately 15,200 km altitude in the southern hemisphere. This orbit has permitted the mapping of regional gravitational structure in the northern hemisphere, and laser altimetry from the MESSENGER spacecraft has yielded a geodetically controlled elevation model for the same hemisphere. The shape of a planet combined with gravity provides fundamental information regarding its internal structure and geologic and thermal evolution. Elevations in the northern hemisphere exhibit a unimodal distribution with a dynamic range of 9.63 km, less than that of the Moon (19.9 km), but consistent with Mercury's higher surface gravitational acceleration. After one Earth-year in orbit, refined models of gravity and topography have revealed several large positive gravity anomalies that coincide with major impact basins. These candidate mascons have anomalies that exceed 100 mGal and indicate substantial crustal thinning and superisostatic uplift of underlying mantle. An additional uncompensated 1000-km-diameter gravity and topographic high at 68 deg N, 33 deg E lies within Mercury's northern volcanic plains. Mercury's northern hemisphere crust is generally thicker at low latitudes than in the polar region. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR2 = 0.353 +/- 0.017, where M=3.30 x 10(exp 23) kg and R=2440 km are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of Cm/C = 0.452 +/- 0.035. One proposed model for Mercury's radial density distribution consistent with these results includes silicate crust and mantle layers overlying a dense solid (possibly Fe-S) layer, a liquid Fe

  19. TRAPPIST-1 Planet Lineup

    NASA Image and Video Library

    2017-02-22

    This artist's concept shows what the TRAPPIST-1 planetary system may look like, based on available data about the planets' diameters, masses and distances from the host star. The system has been revealed through observations from NASA's Spitzer Space Telescope and the ground-based TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope, as well as other ground-based observatories. The system was named for the TRAPPIST telescope. The seven planets of TRAPPIST-1 are all Earth-sized and terrestrial, according to research published in 2017 in the journal Nature. TRAPPIST-1 is an ultra-cool dwarf star in the constellation Aquarius, and its planets orbit very close to it. They are likely all tidally locked, meaning the same face of the planet is always pointed at the star, as the same side of our moon is always pointed at Earth. This creates a perpetual night side and perpetual day side on each planet. TRAPPIST-1b and c receive the most light from the star and would be the warmest. TRAPPIST-1e, f and g all orbit in the habitable zone, the area where liquid water is most likely to be detected. But any of the planets could potentially harbor liquid water, depending on their compositions. In the imagined planets shown here, TRAPPIST-1b is shown as a larger analogue to Jupiter's moon Io. TRAPPIST-1d is depicted with a narrow band of water near the terminator, the divide between a hot, dry day and an ice-covered night side. TRAPPIST-1e and TRAPPIST-1f are both shown covered in water, but with progressively larger ice caps on the night side. TRAPPIST-1g is portrayed with an atmosphere like Neptune's, although it is still a rocky world. TRAPPIST-1h, the farthest from the star, would be the coldest. It is portrayed here as an icy world, similar to Jupiter's moon Europa, but the least is known about it. http://photojournal.jpl.nasa.gov/catalog/PIA21422

  20. Preface (Earth-like planets and moons)

    NASA Astrophysics Data System (ADS)

    Foing, Bernard H.

    2002-10-01

    These proceedings contain a selection of papers from 20 invited review talks and 30 contributed oral or poster presentations given at the ESLAB36 symposium on "Earth-like planets and moons", at ESTEC Noordwijk on 3-8 June 2002. This covers bodies such as Earth, Mercury, Venus, Mars, Moon, Vesta, Io, Europa, Ganymede, Callisto, Titan, Triton, Pluto/Charon and terrestrial exoplanets. The goal is to understand their observed similarities and differences, and give both an Earth-oriented and a cosmic perspective. We reviewed the contribution of recent and upcoming space missions to these studies. The programme was based on comprehensive invited reviews, supported with interdisciplinary contributed papers, and a large body of posters on specific results, methods or planetary objects.

  1. Earth-based optical imaging of Mercury

    NASA Astrophysics Data System (ADS)

    Ksanfomality, L. V.

    2006-01-01

    In recent years, considerable progress has been achieved in producing resolved images of Mercury electronically with short exposures at Earth-based telescopes. For the purpose of obtaining images of the unknown portion of Mercury, the previously started series of observations of this planet by the short exposure method was continued. About 20,000 electronic images of Mercury have been acquired on 1-2 May 2002 under good meteorological conditions during the evening elongation. The phase angle of Mercury was 95-99° and the observed range of longitudes was 210-285°W. Observations were carried out using Ritchy-Chrétien telescope ( D = 1.29 m, F = 9.86 m) with the KS 19 filter cutting wavelengths shorter than about 700 nm. The planet's disk was seen, on average, at an angle of 7.7″. A CCD with a pixel size of 7.4 × 7.4 ncm in the regime of short exposures was used. By processing a great number of electronic images, a sufficiently distinct synthesized image of the unknown portion of Mercury's surface was obtained. The most prominent formation in this region is a giant basin (or cratered "mare") centered at about 8°N, 280°W, which was given a working name "Skinakas basin" (after the name of the observatory where observations were made). By its size, the interior part of this basin exceeds the largest lunar Mare Imbrium. As opposed to Mare Imbrium, the Skinakas basin is presumably of impact origin. Its relief resembles that of Caloris Planitia but the size is much larger. A series of smaller formations are also seen on synthesized images. The resolution obtained on the surface of Mercury is about 100 km, which is close to the telescope diffraction limit. Also considered is the synthesized image obtained at the Mount Bigelow Observatory, on December 4, 2003 (Ritchy-Chrétien telescope, D = 1.54 m, F = 20.79 m, using the same CCD camera).

  2. A Spectral Map Of Mercury From MESSENGER

    NASA Astrophysics Data System (ADS)

    Izenberg, N. R.; Pahsai, P.; Klima, R. L.; Blewett, D. T.; Goudge, T. A.; Solomon, S. C.

    2013-12-01

    We use orbital data from the Mercury Surface and Atmospheric Composition Spectrometer (MASCS) Visible and Near Infrared Spectrograph (VIRS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft to study subtle compositional variations across the surface of Mercury. VIRS reflectance spectra obtained from orbit allow identification and classification of spectral units, many of which collocate with geologic features such as pyroclastic deposits; low-reflectance material (LRM); bright, fresh-appearing impact craters; and hollows. The vast majority of the surface is composed of plains units with brightness and spectral reflectance ratios (e.g., 415 nm / 750 nm and 310 nm / 390 nm) that vary within a small range about mean values for the planet. Analysis of VIRS reflectance data in the context of Mercury Dual Imaging System (MDIS) color and high-resolution images enables identification of large regions with similar spectral properties. Our spectral map of Mercury covers approximately 70% of the planet (excluding polar regions and two regions for which calibration refinement is pending). On the basis of brightness, spectral ratio variations, and superposition relationships in the image data, we define four large-scale spectral units in Mercury plains, as well as six additional spectral units of smaller area. The four large-scale spectral units cover (1) 48.7% (brightness and spectral ratio parameters within a few percent of planetary mean values) (2) 31.6% (higher reflectance, higher 310 nm / 390 nm values than mean), (3) 12.9% (higher reflectance, lower 415 nm / 750 nm values than mean), and (4) 6.8% (lower reflectance and higher 310 nm / 390 nm values than mean) of the mapped area. Spectrally defined plains units correspond broadly to plains units defined by morphology and color imaging; e.g., unit 2 corresponds to the previously defined high-reflectance red plains (HRP), unit 3 to the northern smooth plains and the smooth plains

  3. Current Understanding of Mercury's Magnetosphere before MESSENGER

    NASA Astrophysics Data System (ADS)

    Krimigis, S. M.

    The MESSENGER spacecraft is scheduled to be launched mid-May, 2004 on a trajectory that includes two flybys (October 07, July 08) and eventual orbit insertion in July 2009 around the planet Mercury. Embedded in its payload are instruments to examine the basic properties of the planet's magnetosphere, including magnetometer, plasma, and energetic particle measurements (Gold et al, 2001). Our present knowledge of Mercury's magnetosphere is derived from two nightside Mariner 10 flybys in 1974, 1975 that established the presence of an intrinsic magnetic field and some energetic particles. Unfortunately not even the magnetic dipole term was well-resolved, and the fluxes and identity of energetic particles have been a subject of extensive discussion and varying interpretations (e.g. Armstrong et al, 1975, Christon, 1989). There has been evidence of field-aligned currents (e.g. Slavin et al, 1997), but alternative interpretations of magnetic signatures suggest that the magnetosphere may be driven by changing external boundary conditions (Luhman et al, 1998). These uncertainties, coupled with the observed presence of volatiles (H, He, O, Na, K, Ca) raise obvious questions on current closure, hot plasma injection and acceleration, the frequency with which the planetary surface is exposed to the solar wind, and potential sputtering of material due to particle impingement on the regolith. The talk will review our current knowledge and describe the measurements expected from MESSENGER that will address some of the key science questions. Armstrong et al, JGR, 80, 4015, 1975 Gold et al, Planet and Space Sci, 49, 1467, 2001 Christon, S.P., JGR, 94, 6481, 1989 Slavin et al, Planet and Space Sci, 45, 133, 1997 Luhman et al, JGR, 103, 9113, 1998

  4. Chemistry of planet formation

    NASA Astrophysics Data System (ADS)

    Robinson, Sarah Elaine

    2008-02-01

    This thesis explores how the chemical environment in which planets develop influences planet formation. The total solid mass, gas/solid ratio, and specific ice inventory of protoplanetary disks can dramatically alter the planet's formation timescale, core/atmosphere mass ratio, and atmosphere composition. We present the results of three projects that probe the links between solar nebula composition and giant planet formation. The first project offers evidence that stars with planets exhibit statistically significant silicon and nickel enrichment over the general metal-rich population. To test whether this prediction is compatible with the core accretion theory of planet formation, we construct new numerical simulations of planet formation by core accretion that establish the timescale on which a planet forming at 5 AU reaches rapid gas accretion, t rga , as a function of solid surface density s solid : ( t rga /1 Myr) = (s solid /25.0 g cm -2 ) - 1.44 . This relation enables us to construct Monte Carlo simulations that predict the fraction of star-disk systems that form planets as a function of [Fe/H], [Si/Fe], disk mass, outer disk radius and disk lifetime. Our simulations reproduce both the known planet-metallicity correlation and the planet-silicon correlation reported in this paper. The simulations predict that 15% of Solar-type stars form Jupiter-mass planets, in agreement with 12% predicted from extrapolation of the observed planet frequency-semimajor axis distribution. Despite the success of our Monte Carlo simulation of the planet-silicon correlation at predicting the properties of extrasolar Jovian planets, there is still no in situ core accretion simulation that can successfully account for the formation of Saturn, Uranus or Neptune within the observed 2-3 Myr lifetimes of protoplanetary disks. Since solid accretion rate is directly proportional to the available planetesimal surface density, one way to speed up planet formation is to take a full inventory

  5. Primordial Planet Formation

    NASA Astrophysics Data System (ADS)

    Schild, Rudolph E.; Gibson, Carl H.

    Recent spacecraft observations exploring solar system properties impact standard paradigms of the formation of stars, planets and comets. We stress the unexpected cloud of microscopic dust resulting from the DEEP IMPACT mission, and the existence of molten nodules in STARDUST samples. And the theory of star formation does not explain the common occurrence of binary and multiple star systems in the standard gas fragmentation scenario. No current theory of planet formation can explain the iron core of the earth, under oceans of water. These difficulties are avoided in a scenario where the planet mass objects form primordially and are today the baryonic dark matter. They have been detected in quasar microlensing and anomalous quasar radio brightening bursts. The primordial planets often concentrate together to form a star, with residual matter seen in pre-stellar accretion discs around the youngest stars. These primordial planet mass bodies were formed of hydrogen-helium, aggregated in dense clumps of a trillion at the time of plasma neutralization 380,000 years after the big bang. Most have been frozen and invisible, but are now manifesting themselves in numerous ways as sensitive modern space telescopes become operational. Their key detection signature is their thermal emission spectrum, pegged at the 13.8 degrees Kelvin triple point of hydrogen, the baryonic dark matter (Staplefeldt et al. 1999).

  6. Detection of the Magnetospheric Emissions from Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Lazio, J.

    2014-12-01

    Planetary-scale magnetic fields are a window to a planet's interior and provide shielding of the planet's atmosphere. The Earth, Mercury, Ganymede, and the giant planets of the solar system all contain internal dynamo currents that generate planetary-scale magnetic fields. These internal dynamo currents arise from differential rotation, convection, compositional dynamics, or a combination of these. If coupled to an energy source, such as the incident kinetic or magnetic energy from the solar wind, a planet's magnetic field can produce electron cyclotron masers in its magnetic polar regions. The most well known example of this process is the Jovian decametric emission, but all of the giant planets and the Earth contain similar electron cyclotron masers within their magnetospheres. Extrapolated to extrasolar planets, the remote detection of the magnetic field of an extrasolar planet would provide a means of obtaining constraints on the thermal state, composition, and dynamics of its interior as well as improved understanding of the basic planetary dynamo process. The magnetospheric emissions from solar system planets and the discovery of extrasolar planets have motivated both theoretical and observational work on magnetospheric emissions from extrasolar planets. Stimulated by these advances, the W.M. Keck Institute for Space Studies hosted a workshop entitled "Planetary Magnetic Fields: Planetary Interiors and Habitability." I summarize the current observational status of searches for magnetospheric emissions from extrasolar planets, based on observations from a number of ground-based radio telescopes, and future prospects for ground-based studies. Using the solar system planetary magnetic fields as a guide, future space-based missions will be required to study planets with magnetic field strengths lower than that of Jupiter. I summarize mission concepts identified in the KISS workshop, with a focus on the detection of planetary electron cyclotron maser emission. The

  7. Optimal Planet Properties For Plate Tectonics Through Time And Space

    NASA Astrophysics Data System (ADS)

    Stamenkovic, Vlada; Seager, Sara

    2014-11-01

    Both the time and the location of planet formation shape a rocky planet’s mass, interior composition and structure, and hence also its tectonic mode. The tectonic mode of a planet can vary between two end-member solutions, plate tectonics and stagnant lid convection, and does significantly impact outgassing and biogeochemical cycles on any rocky planet. Therefore, estimating how the tectonic mode of a planet is affected by a planet’s age, mass, structure, and composition is a major step towards understanding habitability of exoplanets and geophysical false positives to biosignature gases. We connect geophysics to astronomy in order to understand how we could identify and where we could find planet candidates with optimal conditions for plate tectonics. To achieve this goal, we use thermal evolution models, account for the current wide range of uncertainties, and simulate various alien planets. Based on our best model estimates, we predict that the ideal targets for plate tectonics are oxygen-dominated (C/O<1) (solar system like) rocky planets of ~1 Earth mass with surface oceans, large metallic cores super-Mercury, rocky body densities of ~7000kgm-3), and with small mantle concentrations of iron 0%), water 0%), and radiogenic isotopes 10 times less than Earth). Super-Earths, undifferentiated planets, and especially hypothetical carbon planets, speculated to consist of SiC and C, are not optimal for the occurrence of plate tectonics. These results put Earth close to an ideal compositional and structural configuration for plate tectonics. Moreover, the results indicate that plate tectonics might have never existed on planets formed soon after the Big Bang—but instead is favored on planets formed from an evolved interstellar medium enriched in iron but depleted in silicon, oxygen, and especially in Th, K, and U relative to iron. This possibly sets a belated Galactic start for complex Earth-like surface life if plate tectonics significantly impacts the build up

  8. Substorms on Mercury?

    NASA Technical Reports Server (NTRS)

    Siscoe, G. L.; Ness, N. F.; Yeates, C. M.

    1974-01-01

    Qualitative similarities between some of the variations in the Mercury encounter data and variations in the corresponding regions of the earth's magnetosphere during substorms are pointed out. The Mariner 10 data on Mercury show a strong interaction between the solar wind and the plant similar to a scaled down version of that for the earth's magnetosphere. Some of the features observed in the night side Mercury magnetosphere suggest time dependent processes occurring there.

  9. Thallium Mercury Laser Development

    DTIC Science & Technology

    1981-01-01

    THALLIUM MERCURY LASER DEVELOPMENT C. S. Liu and D. W. Feldman FINAL REPORT (PHASE III) (Period between Feb. 1, 1980 and Jan. 31, 1981) 0 Contract No...Pittsburgh, Pennsylvania 15235 Approved for public release;IDistribution Unlimited 1/i;THALLIUM MERCURY LASER DEVELOPMENT * , , IS C. S./Liu tRD. W /eldman...9 ’ t4 THALLIUM MERCURY LASER DEVELOPMENT C. S. Liu and D. W. Feldman Westinghouse R&D Center Pittsburgh, Pennsylvania 15235 1

  10. Recipes for planet formation

    NASA Astrophysics Data System (ADS)

    Meyer, Michael R.

    2009-11-01

    Anyone who has ever used baking soda instead of baking powder when trying to make a cake knows a simple truth: ingredients matter. The same is true for planet formation. Planets are made from the materials that coalesce in a rotating disk around young stars - essentially the "leftovers" from when the stars themselves formed through the gravitational collapse of rotating clouds of gas and dust. The planet-making disk should therefore initially have the same gas-to-dust ratio as the interstellar medium: about 100 to 1, by mass. Similarly, it seems logical that the elemental composition of the disk should match that of the star, reflecting the initial conditions at that particular spot in the galaxy.

  11. Magnetic Mystery Planets

    NASA Astrophysics Data System (ADS)

    Fillingim, M.; Brain, D.; Peticolas, L.; Yan, D.; Fricke, K.; Thrall, L.

    2014-07-01

    The magnetic fields of the large terrestrial planets, Venus, Earth, and Mars, are all vastly different from each other. These differences can tell us a lot about the interior structure, interior history, and they can even give us clues to the atmospheric history of these planets. This paper highlights a classroom presentation and accompanying activity that focuses on the differences between the magnetic fields of Venus, Earth, and Mars, what these differences mean, and how we measure these differences. During the activity, students make magnetic field measurements and draw magnetic field lines of “mystery planets” using orbiting “spacecraft” (small compasses). Based on their observations, the students then determine whether they are orbiting Venus-like, Earth-like, or Mars-like planets. This activity is targeted to middle and high school audiences. However, we have also used a scaled-down version with elementary school audiences.

  12. Peru Mercury Inventory 2006

    USGS Publications Warehouse

    Brooks, William E.; Sandoval, Esteban; Yepez, Miguel A.; Howard, Howell

    2007-01-01

    In 2004, a specific need for data on mercury use in South America was indicated by the United Nations Environmental Programme-Chemicals (UNEP-Chemicals) at a workshop on regional mercury pollution that took place in Buenos Aires, Argentina. Mercury has long been mined and used in South America for artisanal gold mining and imported for chlor-alkali production, dental amalgam, and other uses. The U.S. Geological Survey (USGS) provides information on domestic and international mercury production, trade, prices, sources, and recycling in its annual Minerals Yearbook mercury chapter. Therefore, in response to UNEP-Chemicals, the USGS, in collaboration with the Economic Section of the U.S. Embassy, Lima, has herein compiled data on Peru's exports, imports, and byproduct production of mercury. Peru was selected for this inventory because it has a 2000-year history of mercury production and use, and continues today as an important source of mercury for the global market, as a byproduct from its gold mines. Peru is a regional distributor of imported mercury and user of mercury for artisanal gold mining and chlor-alkali production. Peruvian customs data showed that 22 metric tons (t) of byproduct mercury was exported to the United States in 2006. Transshipped mercury was exported to Brazil (1 t), Colombia (1 t), and Guyana (1 t). Mercury was imported from the United States (54 t), Spain (19 t), and Kyrgyzstan (8 t) in 2006 and was used for artisanal gold mining, chlor-alkali production, dental amalgam, or transshipment to other countries in the region. Site visits and interviews provided information on the use and disposition of mercury for artisanal gold mining and other uses. Peru also imports mercury-containing batteries, electronics and computers, fluorescent lamps, and thermometers. In 2006, Peru imported approximately 1,900 t of a wide variety of fluorescent lamps; however, the mercury contained in these lamps, a minimum of approximately 76 kilograms (kg), and in

  13. Mercury emission from crematoria.

    PubMed

    Santarsiero, Anna; Settimo, Gaetano; Dell'andrea, Elena

    2006-01-01

    The purpose of this study, undertaken at a cremator representing an example of current equipment and cremation practices in use in Italy, is to assess the possible mercury emitted during cremation and substantiate the current data available. This paper reports some preliminary results concerning mercury and total particulate matter emissions during three cremation processes. The obtained results gave a mercury concentration ranging from 0.005 to 0.300 mg/m3 and a mercury emission factor ranging from 0.036 to 2.140 g/corpse cremated. The total particulate matter concentration range was 1.0 to 2.4 mg/m3.

  14. 3-D Spherical Convection Modeling Applied to Mercury: Dislocation Versus Diffusion Rheology

    NASA Astrophysics Data System (ADS)

    Robertson, S. D.; King, S. D.

    2016-12-01

    Mercury is the smallest among the terrestrial planets and, prior to NASA's MESSENGER mission was thought to be the least tectonically and volcanically active body. Gravity and moment of inertia from MESSENGER constrain Mercury to have a thin silicate mantle shell of approximately 400 km over a massive iron core. This mantle is thinner than previously thought and the smallest end-member in comparison with the other terrestrial planets. Although Mercury currently has a stagnant lid and the present day mantle is likely not convecting, a significant proportion of Mercury's surface features could have been derived from convection in the viscous mantle. Given Mercury's small size, the amount of volcanism and tectonic activity was a surprise. We investigate the effect of dislocation creep rheology in olivine on the dynamics of Mercury. At the pressures and temperatures of Mercury's mantle, laboratory creep studies indicate that olivine deforms by dislocation creep. Previous studies using diffusion creep rheology find that the thin mantle shell of Mercury quickly becomes diffusive and, this is difficult to reconcile with the surface observations. We use the three-dimensional spherical code, CitcomS, to compare numerical models with both dislocation and diffusion creep. We compare gravity, topography, and mantle temperature as a function of time from the models with constraints on the timing of volcanic and tectonic activity on Mercury. The results show that with the dislocation creep mechanism, there is potential for convective flow in the mantle over billions of years. In contrast, models with the diffusion creep mechanism start with a convecting mantle that transitions to global diffusive cooling within 500 Myrs. Diffusion creep rheology does not adequately produce a dynamic interior that is consistent with the historical volcanic and tectonic evolution of the planet. This research is the result of participation in GLADE, a nine-week summer REU program directed by Dave

  15. Plasma precipitation on Mercury's nightside and its implications for magnetospheric convection and exosphere generation.

    NASA Astrophysics Data System (ADS)

    Raines, J. M.; Slavin, J. A.; Tracy, P.; Gershman, D. J.; Zurbuchen, T.; Dewey, R. M.; Sarantos, M.

    2016-12-01

    Plasma impact onto Mercury's surface can be an important contributor to Mercury's exosphere through the process of ion sputtering. Under some circumstances, this process can produce a substantial fraction of the exosphere. When the impacting plasma originates from the magnetosphere itself, this sputtering process can conversely be considered as a sink for the plasma of the Mercury magnetosphere, providing evidence for the processes at work in that system. One such process is reconnection in Mercury's magnetotail, which can accelerate ions and electrons from the central plasma sheet toward the nightside of the planet. By analogy with processes at Earth, it is hypothesized that as these flows approach the planet, much of the plasma is diverted from impact onto the surface by the increasingly strong planetary magnetic field closer to the planet. The remainder of the plasma is expected to follow nearly dipolar field lines, impacting the nightside surface and potentially contributing to field-aligned currents. We present the first direct evidence that this process is operating at Mercury. We examine ion precipitation events on Mercury's nightside with the Fast Imaging Plasma Spectrometer (FIPS) on the MESSENGER spacecraft, which orbited Mercury from 2011 to 2015. We characterize the energy distributions of these events and their extent in latitude and local time. We use these observations to predict the precipitating proton flux from altitudes as low as 11 km. We use this information to bound the region of Mercury's surface that remains protected from plasma bombardment by the planetary dipole magnetic field, and to explore the implications of this information for magnetospheric convection and exosphere generation at Mercury.

  16. Chronology of heavily cratered terrains on Mercury

    NASA Astrophysics Data System (ADS)

    Marchi, S.; Chapman, C. R.

    2012-12-01

    Imaging of Mercury by Mariner 10 revealed a planet with more extensive plains units than on the Moon. Even in heavily cratered terrain, there is a lack of craters <40 km in diameter, relative to the size-frequency distribution on the Moon, a result attributed to resurfacing by the formation of widespread "intercrater plains". MESSENGER imaging has revealed that the more recent smooth plains are generally the result of widespread volcanism (rather than fluidized impact basin ejecta) and that at least localized volcanism may have persisted until comparatively recent times, despite the crustal contraction evidenced by the numerous lobate scarps. The older intercrater plains may also be volcanic. Here we address the ages of the oldest, most heavily cratered regions on Mercury that may predate most of the visible intercrater plains. We scale to Mercury the lunar crater chronology recently developed by Morbidelli et al., [1] in order to interpret new crater counts on these terrains. We find that these craters are probably not saturated but may have been in equilibrium with a rapid resurfacing process, presumably volcanism that formed the earliest recognized intercrater plains. The crater retention age for this terrain, which contains the oldest large craters on Mercury, is surprisingly young, perhaps hundreds of millions of years younger than the heavily cratered pre-Nectarian terrains on the Moon [2]. These results are important for understanding the early geological and geophysical evolution of Mercury. References: [1] Morbidelli A., Marchi S., Bottke W.F., and Kring D.A. 2012. A sawtooth timeline for the first billion years of the lunar bombardment. Earth and Planetary Science Letters, in press. [2] Marchi S., Bottke W.F., Kring D.A., and Morbidelli A. 2012. The onset of the lunar cataclysm as recorded in its ancient crater populations. Earth and Planetary Science Letters 325, 27-38.

  17. Imaging Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.

    2016-10-01

    High-contrast adaptive optics (AO) imaging is a powerful technique to probe the architectures of planetary systems from the outside-in and survey the atmospheres of self-luminous giant planets. Direct imaging has rapidly matured over the past decade and especially the last few years with the advent of high-order AO systems, dedicated planet-finding instruments with specialized coronagraphs, and innovative observing and post-processing strategies to suppress speckle noise. This review summarizes recent progress in high-contrast imaging with particular emphasis on observational results, discoveries near and below the deuterium-burning limit, and a practical overview of large-scale surveys and dedicated instruments. I conclude with a statistical meta-analysis of deep imaging surveys in the literature. Based on observations of 384 unique and single young (≈5-300 Myr) stars spanning stellar masses between 0.1 and 3.0 M ⊙, the overall occurrence rate of 5-13 M Jup companions at orbital distances of 30-300 au is {0.6}-0.5+0.7 % assuming hot-start evolutionary models. The most massive giant planets regularly accessible to direct imaging are about as rare as hot Jupiters are around Sun-like stars. Dividing this sample into individual stellar mass bins does not reveal any statistically significant trend in planet frequency with host mass: giant planets are found around {2.8}-2.3+3.7 % of BA stars, <4.1% of FGK stars, and <3.9% of M dwarfs. Looking forward, extreme AO systems and the next generation of ground- and space-based telescopes with smaller inner working angles and deeper detection limits will increase the pace of discovery to ultimately map the demographics, composition, evolution, and origin of planets spanning a broad range of masses and ages.

  18. Magnetic flux pileup and plasma depletion in Mercury's subsolar magnetosheath

    NASA Astrophysics Data System (ADS)

    Gershman, Daniel J.; Slavin, James A.; Raines, Jim M.; Zurbuchen, Thomas H.; Anderson, Brian J.; Korth, Haje; Baker, Daniel N.; Solomon, Sean C.

    2013-11-01

    from the Fast Imaging Plasma Spectrometer (FIPS) and Magnetometer (MAG) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft during 40 orbits about Mercury are used to characterize the plasma depletion layer just exterior to the planet's dayside magnetopause. A plasma depletion layer forms at Mercury as a result of piled-up magnetic flux that is draped around the magnetosphere. The low average upstream Alfvénic Mach number (MA ~3-5) in the solar wind at Mercury often results in large-scale plasma depletion in the magnetosheath between the subsolar magnetopause and the bow shock. Flux pileup is observed to occur downstream under both quasi-perpendicular and quasi-parallel shock geometries for all orientations of the interplanetary magnetic field (IMF). Furthermore, little to no plasma depletion is seen during some periods with stable northward IMF. The consistently low value of plasma β, the ratio of plasma pressure to magnetic pressure, at the magnetopause associated with the low average upstream MA is believed to be the cause for the high average reconnection rate at Mercury, reported to be nearly 3 times that observed at Earth. Finally, a characteristic depletion length outward from the subsolar magnetopause of ~300 km is found for Mercury. This value scales among planetary bodies as the average standoff distance of the magnetopause.

  19. Five New Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Marcy, Geoffrey W.; Butler, R. Paul; Vogt, Steven S.; Fischer, Debra A.; Henry, Gregory W.; Laughlin, Greg; Wright, Jason T.; Johnson, John A.

    2005-01-01

    We report multiple Doppler measurements of five nearby FGK main-sequence stars and subgiants obtained during the past 4-6 yr at the Keck Observatory. These stars, namely, HD 183263, HD 117207, HD 188015, HD 45350, and HD 99492, all exhibit coherent variations in their Doppler shifts consistent with a planet in Keplerian motion. The five new planets occupy known realms of planetary parameter space, including a wide range of orbital eccentricities, e=0-0.78, and semimajor axes, 0.1-3.8 AU, that provide further statistical information about the true distributions of various properties of planetary systems. One of the planets, HD 99492b, has a low minimum mass of 0.112MJup=36MEarth. Four of the five planets orbit beyond 1 AU. We describe two quantitative tests of the false alarm probability for Keplerian interpretations of measured velocities. The more robust of these involves Monte Carlo realizations of scrambled velocities as a proxy for noise. Keplerian orbital fits to that ``noise'' yield the distribution of χ2ν to compare with χ2ν from the original (unscrambled) velocities. We establish a 1% false alarm probability as the criterion for candidate planets. All five of these planet-bearing stars are metal-rich, with [Fe/H]>+0.27, reinforcing the strong correlation between planet occurrence and metallicity. From the full sample of 1330 stars monitored at Keck, Lick, and the Anglo-Australian Telescope, the shortest orbital period for any planet is 2.64 days, showing that shorter periods occur less frequently than 0.1% in the solar neighborhood. Photometric observations were acquired for four of the five host stars with an automatic telescope at Fairborn Observatory. The lack of brightness variations in phase with the radial velocities supports planetary-reflex motion as the cause of the velocity variations. No transits were observed, but their occurrence is not ruled out by our observations. Based on observations obtained at the W. M. Keck Observatory, which is

  20. Heat Pipe Planets

    NASA Technical Reports Server (NTRS)

    Moore, William B.; Simon, Justin I.; Webb, A. Alexander G.

    2014-01-01

    When volcanism dominates heat transport, a terrestrial body enters a heat-pipe mode, in which hot magma moves through the lithosphere in narrow channels. Even at high heat flow, a heat-pipe planet develops a thick, cold, downwards-advecting lithosphere dominated by (ultra-)mafic flows and contractional deformation at the surface. Heat-pipes are an important feature of terrestrial planets at high heat flow, as illustrated by Io. Evidence for their operation early in Earth's history suggests that all terrestrial bodies should experience an episode of heat-pipe cooling early in their histories.

  1. Location of Planet X

    SciTech Connect

    Harrington, R.S.

    1988-10-01

    Observed positions of Uranus and Neptune along with residuals in right ascension and declination are used to constrain the location of a postulated tenth planet. The residuals are converted into residuals in ecliptic longitude and latitude. The results are then combined into seasonal normal points, producing average geocentric residuals spaced slightly more than a year apart that are assumed to represent the equivalent heliocentric average residuals for the observed oppositions. Such a planet is found to most likely reside in the region of Scorpius, with considerably less likelihood that it is in Taurus. 8 references.

  2. Mission to Planet Earth

    NASA Technical Reports Server (NTRS)

    Wilson, Gregory S.; Backlund, Peter W.

    1992-01-01

    Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the earth and how it works as a system. Increased understanding of the earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment.

  3. Mission to Planet Earth

    NASA Technical Reports Server (NTRS)

    Tilford, Shelby G.; Asrar, Ghassem; Backlund, Peter W.

    1994-01-01

    Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the Earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic Earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the Earth and how it works as a system. Increased understanding of the Earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment.

  4. Mission to Planet Earth

    NASA Technical Reports Server (NTRS)

    Tilford, Shelby G.; Asrar, Ghassem; Backlund, Peter W.

    1994-01-01

    Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the Earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic Earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the Earth and how it works as a system. Increased understanding of the Earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment.

  5. Mission to Planet Earth

    NASA Technical Reports Server (NTRS)

    Wilson, Gregory S.; Backlund, Peter W.

    1992-01-01

    Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the earth and how it works as a system. Increased understanding of the earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment.

  6. The evolution of Mercury's crust: a global perspective from MESSENGER.

    PubMed

    Denevi, Brett W; Robinson, Mark S; Solomon, Sean C; Murchie, Scott L; Blewett, David T; Domingue, Deborah L; McCoy, Timothy J; Ernst, Carolyn M; Head, James W; Watters, Thomas R; Chabot, Nancy L

    2009-05-01

    Mapping the distribution and extent of major terrain types on a planet's surface helps to constrain the origin and evolution of its crust. Together, MESSENGER and Mariner 10 observations of Mercury now provide a near-global look at the planet, revealing lateral and vertical heterogeneities in the color and thus composition of Mercury's crust. Smooth plains cover approximately 40% of the surface, and evidence for the volcanic origin of large expanses of plains suggests that a substantial portion of the crust originated volcanically. A low-reflectance, relatively blue component affects at least 15% of the surface and is concentrated in crater and basin ejecta. Its spectral characteristics and likely origin at depth are consistent with its apparent excavation from a lower crust or upper mantle enriched in iron- and titanium-bearing oxides.

  7. Comparison of large crater and multiringed basin populations on Mars, Mercury, and the moon

    NASA Technical Reports Server (NTRS)

    Malin, M. C.

    1976-01-01

    The maximum regional areal densities of large impact craters on Mars, Mercury, and the moon appear to be inversely proportional to the surface areas of the planets. This would not be expected if the objects impacting the planetary surfaces came from common sources and were moving with high velocities relative to the planets; rather, a uniform areal density would be anticipated. Another way of stating the observation is that each planet was bombarded by the same number of objects. Two speculative explanations for the observation are that: (1) all planets underwent a uniform bombardment but were resurfaced by processes proportional to planetary surface area, or (2) equally populated families of objects, moving about the sun in orbits similar to those of the planets, were independently depopulated by the respective planets.

  8. Impact-driven supply of sodium and potassium to the atmosphere of Mercury

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.; Zook, H. A.; Potter, A. E.

    1988-01-01

    The Mercury atmosphere is supplied with sodium atoms from both impacting meteoroids and the impacted regolith; the production of vaporized sodium due to such impact varies with the instantaneous distance of Mercury from the sun, in a way that differs from the distance-dependence of those source-and-sink processes driven by solar radiation. Such impact-driven vaporization will yield the Na/K ratio noted in the Mercury atmosphere only if both the meteoroids and the regolith of the planet are deficient in K relative to other solar system objects sampled, other than comets.

  9. Impact-driven supply of sodium and potassium to the atmosphere of Mercury

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.; Zook, H. A.; Potter, A. E.

    1988-01-01

    The Mercury atmosphere is supplied with sodium atoms from both impacting meteoroids and the impacted regolith; the production of vaporized sodium due to such impact varies with the instantaneous distance of Mercury from the sun, in a way that differs from the distance-dependence of those source-and-sink processes driven by solar radiation. Such impact-driven vaporization will yield the Na/K ratio noted in the Mercury atmosphere only if both the meteoroids and the regolith of the planet are deficient in K relative to other solar system objects sampled, other than comets.

  10. The New View of Mercury after MESSENGER's first year in orbit

    NASA Astrophysics Data System (ADS)

    Prockter, L. M.; Solomon, S. C.; McNutt, R. L.; Anderson, B. J.; Blewett, D. T.; Evans, L. G.; Gold, R. E.; Murchie, S. L.; Nittler, L. R.; Phillips, R. J.; Slavin, J. A.; Vervack, R. J.; Zuber, M. T.

    2012-04-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has been making measurements of the innermost planet and its environment nearly continuously since its successful insertion into orbit about Mercury in March 2011. Extensive data from orbit have enabled discoveries about Mercury's composition, geology, interior, magnetic field, and interaction with the solar wind. MESSENGER's first chemical remote sensing measurements of Mercury's surface indicate that the planet's bulk silicate fraction differs from those of the other inner planets and is richer in volatile constituents than predicted by most planetary formation models. Global image mosaics and targeted high-resolution images (to resolutions of 10 m/pixel) reveal that Mercury experienced globally extensive volcanism, including widespread examples of both flood lava and pyroclastic deposits. The tectonic history of Mercury, although dominated by global contractional deformation as first seen by Mariner 10, is more complex than first appreciated, with numerous examples of extensional deformation tied to impact crater and basin modification. Long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history. Several large gravity anomalies, including one candidate mascon, are found in Mercury's northern hemisphere. Crustal thickness in this hemisphere is greater at low latitudes and lessens near the pole, and there is evidence for thinning beneath some impact basins. Measurements of Mercury's moments of inertia require either (i) a mantle density that is too high to be compatible with evidence from elemental remote sensing of Mercury's surface for low mantle abundances of Fe, Al, and Ti or (ii) a solid high-density layer between the silicate mantle and fluid outer core that may be a solidified FeS layer at the top of an Fe-S-Si core. Mercury's magnetic field is dominantly dipolar, but the field is axially symmetric and

  11. Evidence for a basalt-free surface on Mercury and implications for internal heat.

    PubMed

    Jeanloz, R; Mitchell, D L; Sprague, A L; de Pater, I

    1995-06-09

    Microwave and mid-infrared observations reveal that Mercury's surface contains less FeO + TiO2 and at least as much feldspar as the lunar highlands. The results are compatible with the high albedo (brightness) of Mercury's surface at visible wavelengths in suggesting a rock and soil composition that is devoid of basalt, the primary differentiate of terrestrial mantles. The occurrence of a basalt-free, highly differentiated crust is in accord with recent models of the planet's thermal evolution and suggests that Mercury has retained a hot interior as a result of a combination of inefficient mantle convection and minimal volcanic heat loss.

  12. SSES Inner Planets Panel Formulation of Science Priorities

    NASA Astrophysics Data System (ADS)

    Pieters, C. M.; Bullock, M.; Greeley, R.; Jolliff, B.; Sprague, A.; Stofan, E.

    2001-11-01

    Formulation and discussion of science issues for the inner planets are the principal responsibilities of the Inner Planets Panel in the decadal assessment of science priorities for solar system exploration being carried out by the NRC/NAS. We will prepare recommendations on priorities for Mercury, Venus, and the Moon (a subset of COMPLEX will recommend priorities for Mars). Our initial questions focus on the most important results and discoveries of the last few decades and we still are open to input on this query. These clearly need to be highlighted in the report. Looking to the future, our overarching theme is evolving into using the planetary bodies of the inner solar system to understand constraints for forming a habitable world (past, present, and future). From the planetary perspective, what led to the unique character of the planet on which we live? How do Earth-like planets work? What do the inner planets tell us about the future habitability of Earth? How do such questions map into missions that lead to major discoveries or new breakthroughs in understanding? We welcome [URGE!] community input into this discussion. White papers can be posted on the community website [http://www.aas.org/ dps/decadal/] and/or sent by email as a Word attachment to Carle Pieters, the IPP Chair. We are progressing at a rapid pace, and in order for the IPP to absorb and discuss additional community input, we recommend all material be received well before the end of November 2001.

  13. Modeling Mercury in Proteins.

    PubMed

    Parks, J M; Smith, J C

    2016-01-01

    Mercury (Hg) is a naturally occurring element that is released into the biosphere both by natural processes and anthropogenic activities. Although its reduced, elemental form Hg(0) is relatively nontoxic, other forms such as Hg(2+) and, in particular, its methylated form, methylmercury, are toxic, with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg(2+) can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg(2+) to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Clearly, then, understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed molecular picture and circumvent issues associated with toxicity. Here, we describe computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intraprotein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. We describe quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand-binding propensities. We then provide a perspective on how we used chemical reasoning to discover how microorganisms methylate mercury. We also highlight our combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confer mercury resistance in many bacteria. Lastly, we place work on mercury in proteins in the context of what is needed for a comprehensive multiscale model of environmental mercury cycling. © 2016 Elsevier Inc. All rights reserved.

  14. Modeling Mercury in Proteins

    SciTech Connect

    Smith, Jeremy C; Parks, Jerry M

    2016-01-01

    Mercury (Hg) is a naturally occurring element that is released into the biosphere both by natural processes and anthropogenic activities. Although its reduced, elemental form Hg(0) is relatively non-toxic, other forms such as Hg2+ and, in particular, its methylated form, methylmercury, are toxic, with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg2+ can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg2+ to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Clearly, then, understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed picture and circumvent issues associated with toxicity. Here we describe computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intra-protein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. We describe quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand binding propensities. We then provide a perspective on how we used chemical reasoning to discover how microorganisms methylate mercury. We also highlight our combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confers mercury resistance in many bacteria. Lastly, we place work on mercury in proteins in the context of what is needed for a comprehensive multi-scale model of environmental mercury cycling.

  15. The Demographics of Rocky Free-floating Planets and their Detectability by WFIRST

    NASA Astrophysics Data System (ADS)

    Barclay, Thomas; Quintana, Elisa V.; Raymond, Sean N.; Penny, Matthew T.

    2017-06-01

    Planets are thought to form via accretion from a remnant disk of gas and solids around a newly formed star. During this process, material in the disk either remains bound to the star as part of either a planet, a smaller celestial body, or makes up part of the the interplanetary medium; falls into the star; or is ejected from the system. Herein we use dynamical models to probe the abundance and properties of ejected material during late-stage planet formation and estimate their contribution to the free-floating planet population. We present 300 N-body simulations of terrestrial planet formation around a solar-type star, with and without giant planets present, using a model that accounts for collisional fragmentation. In simulations with Jupiter and Saturn analogs, about one-third of the initial (˜5 M ⊕) disk mass is ejected, about half in planets more massive than Mercury but with a mass lower than 0.3 M ⊕, and the remainder in smaller bodies. Most ejections occur within 25 Myr, which is shorter than the timescale typically required for Earth-mass planets to grow (30-100 Myr). When giant planets are omitted from our simulations, almost no material is ejected within 200 Myr and only about 1% of the initial disk is ejected by 2 Gyr. We show that about 2.5 terrestrial-mass planets are ejected per star in the Galaxy. We predict that the space-borne microlensing search for free-floating planets from the Wide-Field Infra-Red Space Telescope will discover up to 15 Mars-mass planets, but few free-floating Earth-mass planets.

  16. The rotational dynamics of Mercury and the state of its core

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    1988-01-01

    Data on the rotational dynamics of Mercury are examined together with possible events that could lead to the current state of rotation. It is shown that the dynamical evolution of Mercury's spin angular momentum controlled by the dissipative processes of tidal friction and relative motion between a solid mantle and a liquid core would lead naturally to the current state of rotation of the Mercury planet. To investigate the possibility that Mercury has a molten core, an experiment is designed for the measurement of the core properties of Mercury. It is shown that it is technically feasible to measure the four parameters necessary for the determination of the existence and the extent of a Mercurian molten core, including the amplitude of the physical vibration about the resonance spin rate, the obliquity, and the gravitational harmonic coefficients.

  17. Expected Geochemical and Mineralogical Properties of Meteorites from Mercury: Inferences from Messenger Data

    NASA Technical Reports Server (NTRS)

    McCubbin, F. M.; McCoy, T. J.

    2016-01-01

    Meteorites from the Moon, Mars, and many types of asteroid bodies have been identified among our global inventory of meteorites, however samples of Mercury and Venus have not been identified. The absence of mercurian and venusian meteorites could be attributed to an inability to recognize them in our collections due to a paucity of geochemical information for Venus and Mercury. In the case of mercurian meteorites, this possibility is further supported by dynamical calculations that suggest mercurian meteorites should be present on Earth at a factor of 2-3 less than meteorites from Mars [1]. In the present study, we focus on the putative mineralogy of mercurian meteorites using data obtained from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, which has provided us with our first quantitative constraints on the geochemistry of planet Mercury. We have used the MESSENGER data to compile a list of mineralogical and geochemical characteristics that a meteorite from Mercury is likely to exhibit.

  18. Determination of the rotation of Mercury from satellite gravimetry

    NASA Astrophysics Data System (ADS)

    Cicalò, S.; Milani, A.

    2012-11-01

    Space missions can have as a goal the determination of the interior structure of a planet: this is the case for the ESA BepiColombo mission to Mercury. Very precise range and range-rate tracking from the Earth and onboard accelerometry will provide a huge amount of data, from which it will be possible to study the gravity field of Mercury and other parameters of interest. Gravity can be used to constrain the interior structure, but cannot uniquely determine the interior mass distribution. A much stronger constraint on the interior can be given by also determining the rotation state of the planet. If the planet is asymmetric enough, the gravity field as measured by an orbiting probe tracked from the Earth contains signatures from the rotation. Are these enough to solve for the rotation state, to the required accuracy, from tracking data alone, without measurements of the surface? In order to reach some result analytically, a simplified analytical model is developed, and the symmetry breaking, occurring when the shape of the planet deviates from spherical symmetry, is characterized by explicit formulae. Moreover, a full cycle numerical simulation of the Radio Science Experiment is performed, including the generation of simulated tracking and accelerometer data and the determination, by least-squares fit, of the Mercury-centric initial conditions of the probe, of Mercury's gravity field and its rotation state, together with other parameters affecting the dynamics. The conclusion is that there is no reason of principle prohibiting the determination of the rotation from gravimetry, and the sensitivity of the measurements and the coverage are good enough to perform the experiment at the required level of accuracy. This will be important also in ensuring independent terms of comparison for the rotation experiment performed with a high-resolution camera. The mission is currently under development and much care has to be taken in guaranteeing the scientific goals even if

  19. Planet Formation and the Characteristics of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    An overview of current theories of planetary growth, emphasizing the formation of extrasolar planets, is presented. Models of planet formation are based upon observations of the Solar System, extrasolar planets, and young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but if they become massive enough before the protoplanetary disk dissipates, then they are able to accumulate substantial amounts of gas. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.

  20. Planet Formation and the Characteristics of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    An overview of current theories of planetary growth, emphasizing the formation of extrasolar planets, is presented. Models of planet formation are based upon observations of the Solar System, extrasolar planets, and young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but if they become massive enough before the protoplanetary disk dissipates, then they are able to accumulate substantial amounts of gas. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.