X-MIME: An Imaging X-ray Spectrometer for Detailed Study of Jupiter's Icy Moons and the Planet's X-ray Aurora

NASA Technical Reports Server (NTRS)

Elsner, R. F.; Ramsey, B. D.; Waite, J. H.; Rehak, P.; Johnson, R. E.; Cooper, J. F.; Swartz, D. A.

2004-01-01

Remote observations with the Chandra X-ray Observatory and the XMM-Newton Observatory have shown that the Jovian system is a source of x-rays with a rich and complicated structure. The planet's polar auroral zones and its disk are powerful sources of x-ray emission. Chandra observations revealed x-ray emission from the Io Plasma Torus and from the Galilean moons Io, Europa, and possibly Ganymede. The emission from these moons is certainly due to bombardment of their surfaces of highly energetic protons, oxygen and sulfur ions from the region near the Torus exciting atoms in their surfaces and leading to fluorescent x-ray emission lines. Although the x-ray emission from the Galilean moons is faint when observed from Earth orbit, an imaging x-ray spectrometer in orbit around these moons, operating at 200 eV and above with 150 eV energy resolution, would provide a detailed mapping (down to 40 m spatial resolution) of the elemental composition in their surfaces. Such maps would provide important constraints on formation and evolution scenarios for the surfaces of these moons. Here we describe the characteristics of X-MIME, an imaging x-ray spectrometer under going a feasibility study for the JIMO mission, with the ultimate goal of providing unprecedented x-ray studies of the elemental composition of the surfaces of Jupiter's icy moons and Io, as well as of Jupiter's auroral x-ray emission.

Development of radiative transfer code for JUICE/SWI mission toward the atmosphere of icy moons of Jupiter

NASA Astrophysics Data System (ADS)

Yamada, Takayoshi; Kasai, Yasuko; Yoshida, Naohiro

2016-07-01

The Submillimeter Wave Instrument (SWI) is one of the scientific instruments on the JUpiter Icy moon Explorer (JUICE). We plan to observe atmospheric compositions including water vapor and its isotopomers in Galilean moons (Io, Europa, Ganymede, and Callisto). The frequency windows of SWI are 530 to 625 GHz and 1080 to 1275 GHz with 100 kHz spectral resolution. We are developing a radiative transfer code in Japan with line-by-line method for Ganymede atmosphere in THz region (0 - 3 THz). Molecular line parameters (line intensity and partition function) were taken from JPL (Jet Propulsion Laboratory) catalogue. The pencil beam was assumed to calculate a spectrum of H _{2}O and CO in rotational transitions at the THz region. We performed comparisons between our model and ARTS (Atmospheric Radiative Transfer Simulator). The difference were less than 10% and 5% for H _{2}O and CO, respectively, under the condition of the local thermodynamic equilibrium (LTE). Comparison with several models with non-LTE assumption will be presented.

A passive low frequency instrument for radio wave sounding the subsurface oceans of the Jovian icy moons: An instrument concept

NASA Astrophysics Data System (ADS)

Hartogh, P.; Ilyushin, Ya. A.

2016-10-01

Exploration of subsurface oceans on Jovian icy moons is a key issue of the icy moons' geology. Electromagnetic wave propagation is the only way to probe their icy mantles from the orbit. In the present paper, a principal concept of a passive interferometric instrument for deep sounding of the icy moons' crust is proposed. Its working principle is measuring and correlating Jupiter's radio wave emissions with reflections from the deep sub-surface of the icy moons. A number of the functional aspects of the proposed experiment are studied, in particular, impact of the wave scattering on the surface terrain on the instrument performance and digital sampling of the noisy signal. Results of the test of the laboratory prototype of the instrument are also presented in the paper.

Feasibility Study of a Nuclear-Stirling Plant for the Jupiter Icy Moons Orbiter

NASA Technical Reports Server (NTRS)

Schmitz, Paul C.; Schreiber, Jeffrey G.; Penswick, L. Barry

2005-01-01

NASA is undertaking the design of a new spacecraft to explore the planet Jupiter and its three moons Calisto, Ganymede and Europa. This proposed mission, known as Jupiter Icy Moons Orbiter (JIMO) would use a nuclear reactor and an associated electrical generation system (Reactor Power Plant-RPP) to provide power to the spacecraft. The JIMO spacecraft is envisioned to use this power for science and communications as well as Electric Propulsion (EP). Among other potential power-generating concepts, previous studies have considered Thermoelectric and Brayton Power conversion systems, coupled to a liquid metal reactor for the JIMO mission. This paper will explore trades in system mass and radiator area for a nuclear reactor power conversion system, however this study will focus on Stirling power conversion. The Stirling convertor modeled in this study is based upon the Component Test Power Convertor design that was designed and operated successfully under the Civil Space Technology Initiative for use with the SP-100 nuclear reactor i the 1980's and early 1990's. The study design is such that two of the four convertors would operate at any time to generate the 100 kWe while the others are held in reserve. For this study the Stirling convertors hot-side temperature is 1050 K, would operate at a temperature ratio of 2.4 for a minimum mass system and would have a system efficiency of 29%. The Stirling convertor would generate high voltage (400 volt), 100 Hz single phase AC that is supplied to the Power Management and Distribution system. The waste hear is removed from the Stirling convertors by a flowing liquid sodium-potassium eutectic and then rejected by a shared radiator. The radiator consists of two coplanar wings, which would be deployed after the reactor is in space. System trades were performed to vary cycle state point temperatures and convertor design as well as power output. Other redundancy combinations were considered to understand the affects of convertor

Objectives for Atmospheres and Ring Science for the Jupiter Icy Moons Orbiter

NASA Astrophysics Data System (ADS)

Ingersoll, A.; Simon-Miller, A.

2003-12-01

offers continuous planet viewing during the 3 months between satellite encounters. The 10-30 kW of power offers advantages for radio occultations and other active sensors. In addition, JIMO can carry a probe, which can determine the water abundance, deep winds, and thermal structure to 100 bars. At the Forum on Concepts and Approaches for JIMO in Houston, Texas on June 14-15, 2003, the Atmospheres and Rings Subgroup came up with the following prioritized list of objectives: 1. Composition, structure, chemistry, and dynamics of Jupiter's atmosphere. 2. Composition, structure, and dynamics of icy moon atmospheres. 3. Composition, structure, dynamics, and time variability of the atmosphere of Io. 4. Nature of the interaction between magnetosphere, satellites, and Jupiter. 5. Structure, composition, energy budget, and variability of satellite tori. 6. Structure and particle properties of the Jovian ring system Each objective has several prioritized investigations, and each investigation has a prioritized list of measurements. These will be presented at the meeting. Some of the measurements require a probe; others can be done from the JIMO orbiter. With or without a probe, the JIMO mission can answer fundamental questions about atmospheres, rings, and satellite tori in the Jupiter system.

Radio Sounding Techniques for the Galilean Icy Moons and their Jovian Magnetospheric Environment

NASA Technical Reports Server (NTRS)

Green, James L.; Markus, Thursten; Fung, Shing F.; Benson, Robert F.; Reinich, Bodo W.; Song, Paul; Gogineni, S. Prasad; Cooper, John F.; Taylor, William W. L.; Garcia, Leonard

2004-01-01

Radio sounding of the Earth's topside ionosphere and magnetosphere is a proven technique from geospace missions such as the International Satellites for Ionospheric Studies (ISIS) and the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). Application of this technique to Jupiter's icy moons and the surrounding Jovian magnetosphere will provide unique remote sensing observations of the plasma and magnetic field environments and the subsurface conductivities, of Europa, Ganymede, and Callisto. Spatial structures of ionospheric plasma above the surfaces of the moons vary in response to magnetic-field perturbations from (1) magnetospheric plasma flows, (2) ionospheric currents from ionization of sputtered surface material, and (3) induced electric currents in salty subsurface oceans and from the plasma flows and ionospheric currents themselves. Radio sounding from 3 kHz to 10 MHz can provide the global electron densities necessary for the extraction of the oceanic current signals and supplements in-situ plasma and magnetic field measurements. While radio sounding requires high transmitter power for subsurface sounding, little power is needed to probe the electron density and magnetic field intensity near the spacecraft. For subsurface sounding, reflections occur at changes in the dielectric index, e.g., at the interfaces between two different phases of water or between water and soil. Variations in sub-surface conductivity of the icy moons can be investigated by radio sounding in the frequency range from 10 MHz to 50 MHz, allowing the determination of the presence of density and solid-liquid phase boundaries associated with oceans and related structures in overlying ice crusts. The detection of subsurface oceans underneath the icy crusts of the Jovian moons is one of the primary objectives of the Jupiter Icy Moons Orbiter (JIMO) mission. Preliminary modeling results show that return signals are clearly distinguishable be&een an ice crust with a thickness of

X-Ray Probes of Jupiter's Auroral Zones, Galilean Moons, and the Io Plasma Torus

NASA Technical Reports Server (NTRS)

Elsner, R. F.; Ramsey, B. D.; Swartz, D. A.; Rehak, P.; Waite, J. H., Jr.; Cooper, J. F.; Johnson, R. E.

2005-01-01

Remote observations from the Earth orbiting Chandra X-ray Observatory and the XMM-Newton Observatory have shown the the Jovian system is a rich and complex source of x-ray emission. The planet's auroral zones and its disk are powerful sources of x-ray emission, though with different origins. Chandra observations discovered x-ray emission from the Io plasma torus and from the Galilean moons Io, Europa, and possibly Ganymede. The emission from the moons is due to bombardment of their surfaces by highly energetic magnetospheric protons, and oxygen and sulfur ions, producing fluorescent x-ray emission lines from the elements in their surfaces against an intense background continuum. Although very faint when observed from Earth orbit, an imaging x-ray spectrometer in orbit around the icy Galilean moons would provide a detail mapping of the elemental composition in their surfaces. Here we review the results of Chandra and XMM-Newton observations of the Jovian system and describe the characteristics of X-MIME, an imaging x-ray spectrometer undergoing study for possible application to future missions to Jupiter such as JIMO. X-MIME has the ultimate goal of providing detailed high-resolution maps of the elemental abundances of the surfaces of Jupiter's icy moons and Io, as well as detailed study of the x-ray mission from the Io plasma torus, Jupiter's auroral zones, and the planetary disk.

Main Power Distribution Unit for the Jupiter Icy Moons Orbiter (JIMO)

NASA Technical Reports Server (NTRS)

Papa, Melissa R.

2004-01-01

Around the year 2011, the Jupiter Icy Moons Orbiter (JIMO) will be launched and on its way to orbit three of Jupiter s planet-sized moons. The mission goals for the JIMO project revolve heavily around gathering scientific data concerning ingredients we, as humans, consider essential: water, energy and necessary chemical elements. The JIM0 is an ambitious mission which will implore propulsion from an ION thruster powered by a nuclear fission reactor. Glenn Research Center is responsible for the development of the dynamic power conversion, power management and distribution, heat rejection and ION thrusters. The first test phase for the JIM0 program concerns the High Power AC Power Management and Distribution (PMAD) Test Bed. The goal of this testing is to support electrical performance verification of the power systems. The test bed will incorporate a 2kW Brayton Rotating Unit (BRU) to simulate the nuclear reactor as well as two ION thrusters. The first module of the PMAD Test Bed to be designed is the Main Power Distribution Unit (MPDU) which relays the power input to the various propulsion systems and scientific instruments. The MPDU involves circuitry design as well as mechanical design to determine the placement of the components. The MPDU consists of fourteen relays of four different variations used to convert the input power into the appropriate power output. The three phase system uses 400 Vo1ts(sub L-L) rms at 1000 Hertz. The power is relayed through the circuit and distributed to the scientific instruments, the ION thrusters and other controlled systems. The mechanical design requires the components to be positioned for easy electrical wiring as well as allowing adequate room for the main buss bars, individual circuit boards connected to each component and power supplies. To accomplish creating a suitable design, AutoCAD was used as a drafting tool. By showing a visual layout of the components, it is easy to see where there is extra room or where the

The long-period librations of large synchronous icy moons

NASA Astrophysics Data System (ADS)

Yseboodt, Marie; Van Hoolst, Tim

2014-11-01

A moon in synchronous rotation has longitudinal librations because of its non-spherical mass distribution and its elliptical orbit around the planet. We study the long-period librations of the Galilean satellites and Titan and include deformation effects and the existence of a subsurface ocean. We take into account the fact that the orbit is not keplerian and has other periodicities than the main period of orbital motion around Jupiter or Saturn due to perturbations by the Sun, other planets and moons. An orbital theory is used to compute the orbital perturbations due to these other bodies. For Titan we also take into account the large atmospheric torque at the semi-annual period of Saturn around the Sun.We numerically evaluate the amplitude and phase of the long-period librations for many interior structure models of the icy moons constrained by the mass, radius and gravity field.

Exchange processes from the deep interior to the surface of icy moons

NASA Astrophysics Data System (ADS)

Grasset, O.

Space exploration provides outstanding images of planetary surfaces. Galileo space- craft around Jupiter, and now Cassini in the saturnian system have revealed to us the variety of icy surfaces in the solar system. While Europa, Enceladus, and maybe Titan present past or even active tectonic and volcanic activities, many other moons have been dead worlds for more than 3 billions years. Composition of ices is also complex and it is now commonly admitted that icy surfaces are never composed of pure ices. Water ice can be mixed with salts (Europa?), with hydrocarbons (Titan?) or with silicates (Callisto). The present surfaces of icy moons are the results of both internal (tectonic; volcanism; mantle composition; magnetic field; . . . ) and external processes (radiations, atmospheres, impacts, . . . ). Internal activity (past or present) is almost unknown. While the surfaces indicate clearly that an important activity existed (Ganymede, Europa, Titan, . . . ) or still exists (Enceladus, Titan?, . . . ), volcanic and tectonic processes within icy mantles are still very poorly understood. This project proposes some key studies for improving our knowledge of exchange processes within icy moons, which are: 1) Surface compositions: Interpretation of mapping spectrometer data. It addresses the interpretation of remote sensing data. These data are difficult to understand and a debate between people involved in Galileo and those who are now trying to interpret Cassini data might be fruitful. As an example, interpretation of Galileo data on Europa are still controversial. It is impossible to affirm that the "non-icy" material which does not present the classic infrared signature of pure ice is due to the presence of magnesium hydrates, sodium hydrates, magnesium sulfurs, "clays", or even altered water ice. Discussion on the subject are still needed. On Titan, the presence of the atmosphere impedes to link IR data from Cassini to the composition of the surface. 2) Past and

Cassini finds an oxygen-carbon dioxide atmosphere at Saturn's icy moon Rhea.

PubMed

Teolis, B D; Jones, G H; Miles, P F; Tokar, R L; Magee, B A; Waite, J H; Roussos, E; Young, D T; Crary, F J; Coates, A J; Johnson, R E; Tseng, W-L; Baragiola, R A

2010-12-24

The flyby measurements of the Cassini spacecraft at Saturn's moon Rhea reveal a tenuous oxygen (O(2))-carbon dioxide (CO(2)) atmosphere. The atmosphere appears to be sustained by chemical decomposition of the surface water ice under irradiation from Saturn's magnetospheric plasma. This in situ detection of an oxidizing atmosphere is consistent with remote observations of other icy bodies, such as Jupiter's moons Europa and Ganymede, and suggestive of a reservoir of radiolytic O(2) locked within Rhea's ice. The presence of CO(2) suggests radiolysis reactions between surface oxidants and organics or sputtering and/or outgassing of CO(2) endogenic to Rhea's ice. Observations of outflowing positive and negative ions give evidence for pickup ionization as a major atmospheric loss mechanism.

Feasibility Study of a Nuclear-Stirling Power Plant for the Jupiter Icy Moons Orbiter

NASA Astrophysics Data System (ADS)

Schmitz, Paul C.; Schreiber, Jeffrey G.; Penswick, L. Barry

2005-02-01

NASA is undertaking the design of a new spacecraft to explore the planet Jupiter and its three moons Calisto, Ganymede and Europa. This proposed mission, known as Jupiter Icy Moons Orbiter (JIMO) would use a nuclear reactor and an associated electrical generation system (Reactor Power Plant - RPP) to provide power to the spacecraft. The JIMO spacecraft is envisioned to use this power for science and communications as well as Electric Propulsion (EP). Among other potential power-generating concepts, previous studies have considered Thermoelectric and Brayton power conversion systems, coupled to a liquid metal reactor for the JIMO mission. This paper will explore trades in system mass and radiator area for a nuclear reactor power conversion system, however this study will focus on Stirling power conversion. Stirling convertors have a long heritage operating in both power generation and the cooler industry, and are currently in use in a wide variety of applications. The Stirling convertor modeled in this study is based upon the Component Test Power Convertor design that was designed and operated successfully under the Civil Space Technology Initiative for use with the SP-100 nuclear reactor in the 1980's and early 1990's. The baseline RPP considered in this study consists of four dual-opposed Stirling convertors connected to the reactor by a liquid lithium loop. The study design is such that two of the four convertors would operate at any time to generate the 100 kWe while the others are held in reserve. For this study the Stirling convertors hot-side temperature is 1050 K, would operate at a temperature ratio of 2.4 for a minimum mass system and would have a system efficiency of 29%. The Stirling convertor would generate high voltage (400 volt), 100 Hz single phase AC that is supplied to the Power Management and Distribution system. The waste heat is removed from the Stirling convertors by a flowing liquid sodium-potassium eutectic and then rejected by a shared

Feasibility Study of a Nuclear-Stirling Power Plant for the Jupiter Icy Moons Orbiter

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

Schmitz, Paul C.; Schreiber, Jeffrey G.; Penswick, L. Barry

2005-02-06

NASA is undertaking the design of a new spacecraft to explore the planet Jupiter and its three moons Calisto, Ganymede and Europa. This proposed mission, known as Jupiter Icy Moons Orbiter (JIMO) would use a nuclear reactor and an associated electrical generation system (Reactor Power Plant - RPP) to provide power to the spacecraft. The JIMO spacecraft is envisioned to use this power for science and communications as well as Electric Propulsion (EP). Among other potential power-generating concepts, previous studies have considered Thermoelectric and Brayton power conversion systems, coupled to a liquid metal reactor for the JIMO mission. This papermore » will explore trades in system mass and radiator area for a nuclear reactor power conversion system, however this study will focus on Stirling power conversion. Stirling convertors have a long heritage operating in both power generation and the cooler industry, and are currently in use in a wide variety of applications. The Stirling convertor modeled in this study is based upon the Component Test Power Convertor design that was designed and operated successfully under the Civil Space Technology Initiative for use with the SP-100 nuclear reactor in the 1980's and early 1990's. The baseline RPP considered in this study consists of four dual-opposed Stirling convertors connected to the reactor by a liquid lithium loop. The study design is such that two of the four convertors would operate at any time to generate the 100 kWe while the others are held in reserve. For this study the Stirling convertors hot-side temperature is 1050 K, would operate at a temperature ratio of 2.4 for a minimum mass system and would have a system efficiency of 29%. The Stirling convertor would generate high voltage (400 volt), 100 Hz single phase AC that is supplied to the Power Management and Distribution system. The waste heat is removed from the Stirling convertors by a flowing liquid sodium-potassium eutectic and then rejected by a

First simultaneous observations of local moon aurora and the moon footprints in Jupiter's polar aurora

NASA Astrophysics Data System (ADS)

Hue, V.; Roth, L.; Grodent, D. C.; Gladstone, R.; Saur, J.; Bonfond, B.

2017-12-01

The interaction of the co-rotating magnetospheric plasma with Jupiter's Galilean moons generates local perturbations and auroral emissions in the moons' tenuous atmospheres. Alfvén waves are launched by this local interaction and travel along Jupiter's field lines triggering various effects that finally lead to the auroral moon footprints far away in Jupiter's polar regions. Within the large Hubble Space Telescope aurora program in support of the NASA Juno mission (HST GO-14634, PI D. Grodent), HST observed the local aurora at the moons Io and Ganymede on three occasions in 2017 while the Juno Ultraviolet Spectrograph simultaneously observed Jupiter's aurora and the moon footprints. In this presentation, we will provide first results from the first-ever simultaneous moon and footprint observations for the case of Io. We compare the temporal variability of the local moon aurora and the Io footprint, addressing the question how much of the footprint variability originates from changes at the moon source and how much originates from processes in the regions that lie in between the moon and Jupiter's poles.

Habitability potential of icy moons: a comparative study

NASA Astrophysics Data System (ADS)

Solomonidou, Anezina; Coustenis, Athena; Encrenaz, Thérèse; Sohl, Frank; Hussmann, Hauke; Bampasidis, Georgios; Wagner, Frank; Raulin, François; Schulze-Makuch, Dirk; Lopes, Rosaly

2014-05-01

environments to look for biomarkers. Currently, for Titan and Enceladus, geophysical models try to explain the possible existence of an oceanic layer that decouples the mantle from the icy crust. If the silicate mantles of Eu-ropa and Ganymede and the liquid sources of Titan and Enceladus are geologically active as on Earth, giving rise to the equivalent of hydrothermal systems, the simultaneous presence of water, geodynamic interactions, chemical en-ergy sources and a diversity of key chemical elements may fulfill the basic conditions for habitability. Titan has been suggested to be a possible cryovolcanic world due to the presence of local complex volcanic-like geomorphol-ogy and the indications of surface albedo changes with time [7,8]. Such dynamic activity that would most probably include tidal heating, possible internal convection, and ice tectonics, is believed to be a pre-requisite of a habitable planetary body as it allows the recycling of minerals and potential nutrients and provides localized energy sources. In a recent study by Sohl et al. [2013], we have shown that tidal forces are a constant and significant source of inter-nal deformation on Titan and the interior liquid water ocean can be relatively warm for reasonable amounts of am-monia concentrations, thus completing the set of parameters needed for a truly habitable planetary body. Such habi-tability indications from bodies at distances of 10 AU, are essential discoveries brought to us by space exploration and which have recently revolutionized our perception of habitability in the solar system. In the solar system's neighborhood, such potential habitats can only be investigated with appropriate designed space missions, like JUICE-Laplace (JUpiter ICy moon Explorer) for Ganymede and Europa [9]. JUICE is an ESA mission to Jupiter and its icy moons, recently selected to launch in 2022. References: [1] Coustenis, A., Encrenaz, Th., in "Life Beyond Earth : the search for habitable worlds in the Universe

Automated Estimation of the Orbital Parameters of Jupiter's Moons

NASA Astrophysics Data System (ADS)

Western, Emma; Ruch, Gerald T.

2016-01-01

Every semester the Physics Department at the University of St. Thomas has the Physics 104 class complete a Jupiter lab. This involves taking around twenty images of Jupiter and its moons with the telescope at the University of St. Thomas Observatory over the course of a few nights. The students then take each image and find the distance from each moon to Jupiter and plot the distances versus the elapsed time for the corresponding image. Students use the plot to fit four sinusoidal curves of the moons of Jupiter. I created a script that automates this process for the professor. It takes the list of images and creates a region file used by the students to measure the distance from the moons to Jupiter, a png image that is the graph of all the data points and the fitted curves of the four moons, and a csv file that contains the list of images, the date and time each image was taken, the elapsed time since the first image, and the distances to Jupiter for Io, Europa, Ganymede, and Callisto. This is important because it lets the professor spend more time working with the students and answering questions as opposed to spending time fitting the curves of the moons on the graph, which can be time consuming.

Theoretical studies of the radar properties of the icy Galilean moons of Jupiter

NASA Technical Reports Server (NTRS)

Eshleman, Von R.

1993-01-01

The icy Galilean satellites of Jupiter - Europa, Ganymede, and Callisto - have unusual radar scattering properties compared with those of the terrestrial planets or Earth's Moon. There are three main features of the data that distinguish these targets: (1) the radar cross-section normalized by the geometrical cross-section is an order of magnitude larger than that of any terrestrial planet; (2) the reflected power is almost evenly distributed between two orthogonal polarizations with more power being returned in the same circular polarization as was transmitted whereas virtually all of the power returned from the terrestrial planets is contained in the opposite circular polarization to the one that was transmitted; and (3) the echo power spectra have a broad shape indicating a nearly uniformly radar-bright surface in contrast to the spectra from the terrestrial planets that contain a strong quasi-specular component from the vicinity of the sub-radar point and very little reflected power from the rest of the surface. The normalized radar cross-sections decrease as the areal water ice coverage decreases from Europa to Ganymede to Callisto. Recently, radar echoes from the polar caps of Mars and Mercury, and from Saturn's satellite Titan imply similarly strong cross-sections and have classically unexpected polarization properties and it is also thought that this is due to the presence of ice on the surface. A model called the radar glory model is analyzed and it is shown that the main features of the radar echoes calculated from this model agree well with the observations from all three icy Galilean satellites. This model involves long radar paths in the ice below the surface and special structures in which the refractive index decreases abruptly at a hemispherical boundary. It is not known whether such structures exist or how they could be created, but possible scenarios can be imagined such as the formation of an impact crater followed by deposition of a frost layer

Polymerization of Building Blocks of Life on Europa and Other Icy Moons.

PubMed

Kimura, Jun; Kitadai, Norio

2015-06-01

The outer Solar System may provide a potential habitat for extraterrestrial life. Remote sensing data from the Galileo spacecraft suggest that the jovian icy moons--Europa, Ganymede, and possibly Callisto--may harbor liquid water oceans underneath their icy crusts. Although compositional information required for the discussion of habitability is limited because of significantly restricted observation data, organic molecules are ubiquitous in the Universe. Recently, in situ spacecraft measurements and experiments suggest that amino acids can be formed abiotically on interstellar ices and comets. These amino acids could be continuously delivered by meteorite or comet impacts to icy moons. Here, we show that polymerization of organic monomers, in particular amino acids and nucleotides, could proceed spontaneously in the cold environment of icy moons, in particular the jovian icy moon Europa as a typical example, based on thermodynamic calculations, though kinetics of formation are not addressed. Observed surface temperature on Europa is 120 and 80 K in the equatorial region and polar region, respectively. At such low temperatures, Gibbs energies of polymerization become negative, and the estimated thermal structure of the icy crust should contain a shallow region (i.e., at a depth of only a few kilometers) favorable for polymerization. Investigation of the possibility of organic monomer polymerization on icy moons could provide good constraints on the origin and early evolution of extraterrestrial life.

Status of the Ganymede Laser Altimeter (GALA) for ESA's Jupiter Icy Moons Explorer (JUICE)

NASA Astrophysics Data System (ADS)

Hussmann, Hauke; Luedicke, Fabian

2017-04-01

The Ganymede Laser Altimeter (GALA) is one of the instruments selected for ESA's Jupiter Icy Moons Explorer (JUICE). A fundamental goal of any exploratory space mission is to characterize and measure the shape, topography, and rotation of the target bodies. A state of the art tool for this task is laser altimetry because it can provide absolute topographic height and position with respect to a body centered reference system. With respect to Ganymede, the GALA instrument aims at mapping of global, regional and local topography; confirming the global subsurface ocean and further characterization of the water-ice/liquid shell by monitoring the dynamic response of the ice shell to tidal forces; providing constraints on the forced physical librations and spin-axis obliquity; determining Ganymede's shape; obtaining detailed topographic profiles across the linear features of grooved terrain, impact structures, possible cryo-volcanic features and other different surface units; providing information about slope, roughness and albedo (at 1064nm) of Ganymede's surface. After several flyby's (Ganymede, Europa, Callisto) it is scheduled that the JUICE orbiter will enter first into an elliptical orbit (200 km x 10.000 km) for around 150 days and then into a circular orbit (500 km) around Ganymede for 130 days. Accordingly to the different orbits and trajectories, distances to the moons respectively, the spot size of the GALA laser varies between 21 m and 140 m. GALA uses the direct-detection (classical) approach of laser altimetry. Laser pulses are emitted at a wavelength of 1064 nm by using an actively Q-switched Nd:Yag laser. The pulse energy and pulse repetition frequency are 17 mJ at 30 Hz (nominal), respectively. For targeted observations and flybys the frequency can be switched to 50 Hz. The emission time of each pulse is measured by the detector. The beam is reflected from the surface and received at a 25 cm diameter telescope. The returning laser pulse is refocused onto

Jupiter's Water Worlds

NASA Technical Reports Server (NTRS)

Pappalardo, R. T.

2004-01-01

When the twin Voyager spacecraft cruised past Jupiter in 1979, they did more than rewrite the textbooks on the giant planet. Their cameras also unveiled the astounding diversity of the four planet-size moons of ice and stone known as the Galilean satellites. The Voyagers revealed the cratered countenance of Callisto, the valleys and ridges of Ganymede, the cracked face of Europa, and the spewing volcanoes of Io. But it would take a spacecraft named for Italian scientist Galileo, who discovered the moons in 1610, to reveal the true complexity of these worlds and to begin to divulge their interior secrets. Incredibly, the Galileo data strongly suggest that Jupiter's three large icy moons (all but rocky Io) hide interior oceans.

Polymerization of Building Blocks of Life on Europa and Other Icy Moons

PubMed Central

Kitadai, Norio

2015-01-01

Abstract The outer Solar System may provide a potential habitat for extraterrestrial life. Remote sensing data from the Galileo spacecraft suggest that the jovian icy moons—Europa, Ganymede, and possibly Callisto—may harbor liquid water oceans underneath their icy crusts. Although compositional information required for the discussion of habitability is limited because of significantly restricted observation data, organic molecules are ubiquitous in the Universe. Recently, in situ spacecraft measurements and experiments suggest that amino acids can be formed abiotically on interstellar ices and comets. These amino acids could be continuously delivered by meteorite or comet impacts to icy moons. Here, we show that polymerization of organic monomers, in particular amino acids and nucleotides, could proceed spontaneously in the cold environment of icy moons, in particular the jovian icy moon Europa as a typical example, based on thermodynamic calculations, though kinetics of formation are not addressed. Observed surface temperature on Europa is 120 and 80 K in the equatorial region and polar region, respectively. At such low temperatures, Gibbs energies of polymerization become negative, and the estimated thermal structure of the icy crust should contain a shallow region (i.e., at a depth of only a few kilometers) favorable for polymerization. Investigation of the possibility of organic monomer polymerization on icy moons could provide good constraints on the origin and early evolution of extraterrestrial life. Key Words: Planetary science—Europa—Planetary habitability and biosignatures—Extraterrestrial life—Extraterrestrial organic compounds. Astrobiology 15, 430–441. PMID:26060981

Physicochemical Requirements Inferred for Chemical Self-Organization Hardly Support an Emergence of Life in the Deep Oceans of Icy Moons.

PubMed

Pascal, Robert

2016-05-01

An approach to the origin of life, focused on the property of entities capable of reproducing themselves far from equilibrium, has been developed recently. Independently, the possibility of the emergence of life in the hydrothermal systems possibly present in the deep oceans below the frozen crust of some of the moons of Jupiter and Saturn has been raised. The present report is aimed at investigating the mutual compatibility of these alternative views. In this approach, the habitability concept deduced from the limits of life on Earth is considered to be inappropriate with regard to emerging life due to the requirement for an energy source of sufficient potential (equivalent to the potential of visible light). For these icy moons, no driving force would have been present to assist the process of emergence, which would then have had to rely exclusively on highly improbable events, thereby making the presence of life unlikely on these Solar System bodies, that is, unless additional processes are introduced for feeding chemical systems undergoing a transition toward life and the early living organisms. Icy moon-Bioenergetics-Chemical evolution-Habitability-Origin of life. Astrobiology 16, 328-334.

Remote Sensing of Icy Galilean Moon Surface and Atmospheric Composition Using Low Energy (1 eV-4 keV) Neutral Atom Imaging

NASA Technical Reports Server (NTRS)

Collier, M. R.; Sittler, E.; Chornay, D.; Cooper, J. F.; Coplan, M.; Johnson, R. E.

2004-01-01

We describe a low energy neutral atom imager suitable for composition measurements Europa and other icy Galilean moons in the Jovian magnetosphere. This instrument employs conversion surface technology and is sensitive to either neutrals converted to negative ions, neutrals converted to positive ions and the positive ions themselves depending on the power supply. On a mission such as the Jupiter Icy Moons Orbiter (JIMO), two back-to-back sensors would be flown with separate power supplies fitted to the neutral atom and iodneutral atom sides. This will allow both remote imaging of 1 eV < E < 4 keV neutrals from icy moon surfaces and atmospheres, and in situ measurements of ions at similar energies in the moon ionospheres and Jovian magnetospheric plasma. The instrument provides composition measurements of the neutrals and ions that enter the spectrometer with a mass resolution dependent on the time-of-flight subsystem and capable of resolving molecules. The lower energy neutrals, up to tens of eV, arise from atoms and molecules sputtered off the moon surfaces and out of the moon atmospheres by impacts of more energetic (keV to MeV) ions from the magnetosphere. Direct Simulation Monte Carlo (DSMC) models are used to convert measured neutral abundances to compositional distributions of primary and trace species in the sputtered surfaces and atmospheres. The escaping neutrals can also be detected as ions after photo- or plasma-ionization and pickup. Higher energy, keV neutrals come from charge exchange of magnetospheric ions in the moon atmospheres and provide information on atmospheric structure. At the jovicentric orbits of the icy moons the presence of toroidal gas clouds, as detected at Europa's orbit, provide M e r opportunities to analyze both the composition of neutrals and ions originating from the moon surfaces, and the characteristics of magnetospheric ions interacting with neutral cloud material. Charge exchange of low energy ions near the moons, and

Himalia, a Small Moon of Jupiter

NASA Technical Reports Server (NTRS)

2001-01-01

NASA's Cassini spacecraft captured images of Himalia, the brightest of Jupiter's outer moons, on Dec. 19, 2000, from a distance of 4.4 million kilometers (2.7 million miles).

This near-infrared image, with a resolution of about 27 kilometers (17 miles) per pixel, indicates that the side of Himalia facing the spacecraft is roughly 160 kilometers (100 miles) in the up-down direction. Himalia probably has a non-spherical shape. Scientists believe it is a body captured into orbit around Jupiter, most likely an irregularly shaped asteroid.

In the main frame, an arrow indicates Himalia. North is up. The inset shows the little moon magnified by a factor of 10, plus a graphic indicating Himalia's size and the direction of lighting (with sunlight coming from the left). Cassini's pictures of Himalia were taken during a brief period when Cassini's attitude was stabilized by thrusters instead of by a steadier reaction-wheel system. No spacecraft or telescope had previously shown any of Jupiter's outer moons as more than a star-like single dot.

Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

Thermo-chemical Ice Penetrator for Icy Moons

NASA Astrophysics Data System (ADS)

Arenberg, J. W.; Lee, G.; Harpole, G.; Zamel, J.; Sen, B.; Ross, F.; Retherford, K. D.

2016-12-01

The ability to place sensors or to take samples below the ice surface enables a wide variety of potential scientific investigations. Penetrating an ice cap can be accomplished via a mechanical drill, laser drill, kinetic impactor, or heated penetrator. This poster reports on the development of technology for the latter most option, namely a self-heated probe driven by an exothermic chemical reaction: a Thermo-chemical ice penetrator (TChIP). Our penetrator design employs a eutectic mix of alkali metals that produce an exothermic reaction upon contact with an icy surface. This reaction increases once the ice starts melting, so no external power is required. This technology is inspired by a classified Cold-War era program developed at Northrop Grumman for the US Navy. Terrestrial demonstration of this technology took place in the Arctic; however, this device cannot be considered high TRL for application at the icy moons of the solar system due to the environmental differences between Earth's Arctic and the icy moons. These differences demand a TChIP design specific to these cold, low mass, airless worlds. It is expected that this model of TChIP performance will be complex, incorporating all of the forces on the penetrator, gravity, the thermo-chemistry at the interface between penetrator and ice, and multi-phase heat and mass transport, and hydrodynamics. Our initial efforts are aimed at the development of a validated set of tools and simulations to predict the performance of the penetrator for both the environment found on these icy moons and for a terrestrial environment. The purpose of the inclusion of the terrestrial environment is to aid in model validation. Once developed and validated, our models will allow us to design penetrators for a specific scientific application on a specific body. This poster discusses the range of scientific investigations that are enabled by TChIP. We also introduce the development plan to advance TChIP to the point where it can be

Traveling Wave Tube (TVT) RF Power Combining Demonstration for use in the Jupiter Icy Moons Orbiter (JIMO)

NASA Technical Reports Server (NTRS)

Downey, Joseph A.

2004-01-01

The Jupiter Icy Moons Orbiter (JIMO) is set to launch between the years 2012 and 2015. It will possibly utilize a nuclear reactor power source and ion engines as it travels to the moons of Jupiter. The nuclear reactor will produce hundreds of kilowatts of power for propulsion, communication and various scientific instruments. Hence, the RF amplification devices aboard will be able to operate at a higher power level and data rate. The initial plan for the communications system is for an output of 1000 watts of RF power, a data rate of at least 10 megabits a second, and a frequency of 32 GHz. A higher data rate would be ideal to fully utilize the instruments aboard JIMO. At NASA Glenn, one of our roles in the JIMO project is to demonstrate RF power combining using multiple traveling wave tubes (TWT). In order for the power of separate TWT s to be combined, the RF output waves from each must be in-phase and have the same amplitude. Since different tubes act differently, we had to characterize each tube using a Network Analyzer. We took frequency sweeps and power sweeps to characterize each tube to ensure that they will behave similarly under the same conditions. The 200 watt Dornier tubes had been optimized to run at a lower power level (120 watts) for their extensive use in the ACTS program, so we also had to experiment with adjusting the voltage settings on several internal components (helix, anode, collector) of the tubes to reach the full 200 watt potential. from the ACTS program. Phase shifters and power attenuators were placed in the waveguide circuit at the inputs to the tubes so that adjustments could be made individually to match them exactly. A magic tee was used to route and combine the amplified electromagnetic RF waves on the tube output side. The demonstration of 200 watts of combined power was successful with efficiencies greater than 90% over a 500 MHz bandwidth. The next step will be to demonstrate the use of three amplifiers using two magic tees by

Project GALILEO: Farewell to the Major Moons of Jupiter

NASA Astrophysics Data System (ADS)

Theilig, E.

2002-01-01

After a six year odyssey, Galileo has completed its survey of the large moons of Jupiter. In the four years since the end of the primary mission, Galileo provided new insights into the fundamental questions concerning Jupiter and its moons and magnetosphere. Longevity, changing orbital geometry, and multiple flybys afforded the opportunity to distinguish intrinsic versus induced magnetic fields on the Galilean moons, to characterize the dusk side of the magnetosphere, to acquire high resolution observations supporting the possibility of subsurface water within Europa, Ganymede, and Callisto, and to monitor the highly dynamic volcanic activity of Io. In January 2002, a final gravity assist placed the spacecraft on a two-orbit trajectory culminating in a Jupiter impact in September 2003. With the successful completion of the Io encounters, plans are being made for the final encounter of the mission. In November 2002, the spacecraft will fly one Jupiter radius above the planet's cloud-tops, sampling the inner magnetosphere and the gossamer rings. The trajectory will take Galileo close enough to Amalthea, (a small inner moon) to obtain the first gravity data for this body. Because a radiation dose of 73 krads is expected on this encounter, which will bring the total radiation dose to greater than four times the spacecraft design limits, the command sequence has to account for the possibility of subsystem failure and the loss of spacecraft control after this perijove passage. One of the primary objectives this year has been to place the spacecraft on a trajectory to impact Jupiter on orbit 35. Galileo's discovery of water beneath the frozen surface of Europa raised concerns about forward contamination by inadvertently impacting that moon and resulted in an end of mission requirement to dispose of the spacecraft. A risk assessment of the final two Io encounters was performed to manage the project's ability to meet this requirement. Radiation affected the extended mission

Icy Moon Absorption Signatures: Probes of Saturnian Magnetospheric Dynamics and Moon Activity

NASA Astrophysics Data System (ADS)

Roussos, E.; Krupp, N.; Jones, G. H.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Motschmann, U.; Dougherty, M. K.; Lagg, A.; Woch, J.

2006-12-01

After the first flybys at the outer planets by the Pioneer and Voyager probes, it became evident that energetic charged particle absorption features in the radiation belts are important tracers of magnetospheric dynamical features and parameters. Absorption signatures are especially important for characterizing the Saturnian magnetosphere. Due to the spin and magnetic axes' near-alignment, losses of particles to the icy moon surfaces and rings are higher compared to the losses at other planetary magnetospheres. The refilling rate of these absorption features (termed "micorsignatures") can be associated with particle diffusion. In addition, as these microsignatures drift with the properties of the pre-depletion electrons, they provide us direct information on the drift shell structure in the radiation belts and the factors that influence their shape. The multiple icy moon L-shell crossings by the Cassini spacecraft during the first 2 years of the mission provided us with almost 100 electron absorption events by eight different moons, at various longitudinal separations from each one and at various electron energies. Their analysis seems to give a consistent picture of the electron diffusion source and puts aside a lot of inconsistencies that resulted from relevant Pioneer and Voyager studies. The presence of non-axisymmetric particle drift shells even down to the orbit of Enceladus (3.98 Rs), also revealed through this analysis, suggests either large ring current disturbances or the action of global or localized electric fields. Finally, despite these absorption signatures being observed far from the originating moons, they can give us hints on the nature of the local interaction between each moon and the magnetospheric plasma. It is, nevertheless, beyond any doubt that energetic charged particle absorption signatures are a very powerful tool that can be used to effectively probe a series of dynamical processes in the Saturnian magnetosphere.

Tour of Jupiter Galilean moons: Winning solution of GTOC6

NASA Astrophysics Data System (ADS)

Colasurdo, Guido; Zavoli, Alessandro; Longo, Alessandro; Casalino, Lorenzo; Simeoni, Francesco

2014-09-01

The paper presents the trajectory designed by the Italian joint team Politecnico di Torino & Sapienza Università di Roma (Team5), winner of the 6th edition of the Global Trajectory Optimization Competition (GTOC6). In the short time available in these competitions, Team5 resorted to basic knowledge, simple tools and a powerful indirect optimization procedure. The mission concerns a 4-year tour of the Jupiter Galilean moons. The paper explains the strategy that was preliminarily devised and eventually implemented by looking for a viable trajectory. The first phase is a capture that moves the spacecraft from the arrival hyperbola to a low-energy orbit around Jupiter. Six series of flybys follow; in each one the spacecraft orbits Jupiter in resonance with a single moon; criteria to construct efficient chains of resonant flybys are presented. Transfer legs move the spacecraft from resonance with a moon to another one; precise phasing of the relevant moons is required; mission opportunities in a 11-year launch window are found by assuming ballistic trajectories and coplanar circular orbits for the Jovian satellites. The actual trajectory is found by using an indirect technique.

Laboratory permittivity measurements of icy planetary analogs in the millimeter and submillimeter domains, in relation with JUICE mission.

NASA Astrophysics Data System (ADS)

Brouet, Y.; Jacob, K.; Murk, A.; Poch, O.; Pommerol, A.; Thomas, N.; Levasseur-Regourd, A. C.

2015-12-01

The European Space Agency's JUpiter ICy moons Explorer (JUICE) spacecraft is planned for launch in 2022 and arrival at Jupiter in 2030. It will observe the planet Jupiter and three of its largest moons, Ganymede, Callisto and Europa. One instrument on the JUICE spacecraft is the Sub-millimeter Wave Instrument (SWI), which will measure brightness temperatures from Jupiter's stratosphere and troposphere, and from subsurfaces of Jupiter's icy moons. In the baseline configuration SWI consists of two tunable sub-millimeter wave receivers operating from 530 to 625 GHz. As an alternative one of the receivers could cover the range of 1080 and 1275 GHz. Inversion models are strongly dependent on the knowledge of the complex relative permittivity (hereafter permittivity) of the target material to retrieve the physical properties of the subsurface (e.g. [1][2]). We set up a laboratory experiment allowing us to perform reproducible measurements of the complex scattering parameters S11 and S21 in the ranges of 70 to 110 GHz, of 100 to 160 GHz, of 140 to 220 GHz, of 140 to 220 GHz and of 510 to 715 GHz. These scattering parameters can be used to retrieve the permittivity of icy analogs of the surfaces and subsurfaces of Jupiter's icy moons in order to prepare the data interpretation of SWI [3]. The measurements are performed under laboratory conditions with a quasi-optical bench (Institute of Applied Physics, University of Bern). The icy analogs that we prepare in the Laboratory for Outflow Studies of Sublimating Materials (LOSSy, Physics Institute, University of Bern), include two different porous water ice samples composed of fine-grained ice particles with a size range of 4 to 6 microns and ice particles with a size range of 50 to 100 microns [4][5]; and possibly CO2 ice. We will present the general experimental set-up and the first results in the context to prepare the data interpretation of SWI. [1] Ulaby, F. T., Long, D. G., 2014. Microwave radar and radiometric remote

Photographer : JPL Callisto , The outermost Galilean Satellite , or Moon , of Jupiter, as taken by

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Callisto , The outermost Galilean Satellite , or Moon , of Jupiter, as taken by Voyager I . Range : About 7 Million km (5 Million miles) . Callisto, the darkest of the Galilean Satellites, still nearly twice as bright as the Earth's Moon, is seen here from the face that always faces Jupiter. All of the Galilean Satellites always show the same face to Jupiter, as the Earth's moon does to Earth. The Surface shows a mottled appearance of bright and dark patches. The former reminds scientists of rayed or bright haloed craters, similiar to those seen on earth's Moon. This color photo is assembled from 3 black and wite images taken though violet, orange, & green filters

Simon Marius vs. Galileo: Who First Saw Moons of Jupiter?

NASA Astrophysics Data System (ADS)

Pasachoff, Jay M.; Van Helden, Albert

2016-10-01

In his almanac for 1612 and book Mundus Iovalis of 1614, Simon Marius in Germany reported his discovery of moons around Jupiter, which he started writing down in late 1609 in the Julian calendar, which translated to 8 January 1610 in the Gregorian calendar in use by Galileo in Italy. Is Marius to be believed? Galileo certainly did not. But a Dutch jury of experts about three hundred years later reported that they validated the claim that Marius independently discovered the moons of Jupiter one day after Galileo first both saw and wrote down his discovery! There is no doubt that the names Io, Europa, Ganymede, and Callisto came from Marius (to whom they were suggested by Kepler). See JMP's Journal for the History of Astronomy article, 46(2), 218-234 (2015).Marius wrote that he had been observing the moons around Jupiter since November 1609 (Julian), using a neighboring nobleman's telescope, which would mean that he actually saw the Jupiter satellites first (though publish or perish). Whether this feat was technically possible comes down to discussions of the capabilities of telescopes in the early 17th century.The quadricentennial of Marius's book was celebrated in Nuremberg with a symposium that is now in press in German with an English translation expected. One of us (AVH) has recently prepared a complete English translation of Marius's book, superseding the partial translation made 100 years ago. There is no evidence that, whether he saw what we now call the Galilean satellites first or not, Marius appreciated their cosmological significance the way that Galileo soon did. And Marius was certainly the first to publish tables of the moons of Jupiter.We thank the Chapin Library of Williams College and the Huntington Library for assistance with first editions of Marius's 1614 book, and we thank Pierre Leich of the Simon Marius Gesellschaft for his consultations.

Engineering a Solution to Jupiter Exploration

NASA Technical Reports Server (NTRS)

Clark, Karla; Magner, Thomas; Lisano, Michael; Pappalardo, Robert

2010-01-01

The Europa Jupiter System Mission (EJSM) would be an international mission with the overall theme of investigating the emergence of habitable worlds around gas giants. Its goals are to (1) explore Europa to investigate its habitability, (2) characterize Ganymede as a planetary object including its potential habitability and (3) explore the Jupiter system as an archetype for gas giants. NASA and ESA have concluded a detailed joint study of a mission to Europa, Ganymede, and the Jupiter system with conceptual orbiters developed by NASA and ESA. The baseline EJSM architecture consists of two primary elements operating simultaneously in the Jovian system: the NASA-led Jupiter Europa Orbiter (JEO), and the ESA-led Jupiter Ganymede Orbiter (JGO). JEO and JGO would execute an intricately choreographed exploration of the Jupiter System before settling into orbit around Europa and Ganymede, respectively. EJSM would directly address themes concerning the origin and evolution of satellite systems and water-rich environments in icy satellites. The potential habitability of the ocean-bearing moons Europa and Ganymede would be investigated, by characterizing the geophysical, compositional, geological, and external processes that affect these icy worlds. EJSM would also investigate Io and Callisto, Jupiter's atmosphere, and the Jovian magnetosphere. By understanding the Jupiter system and unraveling its history, the formation and evolution of gas giant planets and their satellites would be better known. Most importantly, EJSM would shed new light on the potential for the emergence of life in the celestial neighborhood and beyond. The EJSM baseline architecture would provide opportunities for coordinated synergistic observations by JEO and JGO of the Jupiter and Ganymede magnetospheres, the volcanoes and torus of Io, the atmosphere of Jupiter, and comparative planetology of icy satellites. Each spacecraft would conduct both synergistic dual-spacecraft investigations and stand

Fitting Orbits to Jupiter's Moons with a Spreadsheet.

ERIC Educational Resources Information Center

Bridges, Richard

1995-01-01

Describes how a spreadsheet is used to fit a circular orbit model to observations of Jupiter's moons made with a small telescope. Kepler's Third Law and the inverse square law of gravity are observed. (AIM)

Why Europa's icy shell may convect, but ice sheets do not: a glaciological perspective

NASA Astrophysics Data System (ADS)

Bassis, J. N.

2016-12-01

Jupiter's moon Europa is covered in an icy shell that lies over a liquid ocean. Geological evidence and numerical models suggest that Europa's icy shell convects, providing the possibility that Europa may experience a form of plate tectonics and could even harbor life in its subsurface ocean. The hypothesis that Europa convects is supported by both models and geological evidence. Surprisingly, when we apply similar calculations and (assumptions) used by planetary scientists to infer convection in icy moons like Europa we find that these models also predict that vigorous convection should also occur in portions of our own terrestrial ice sheets and ice shelves where we have firm evidence to the contrary. We can explain the lack of convection within our own ice sheets by recognizing that instead of the diffusion creep limited rheology frequently invoked by planetary scientists, terrestrial ice undergoes power-law creep down to very low strain rates. Glaciological studies find that power-law creep is required to explain the structure of vertical strain rate near ice sheet divides and shape of the ice sheets near an ice divide. However, when we now apply a rheology that is consistent with terrestrial ice sheet dynamics to icy moon conditions, we find conditions are far less favorable for convection in icy moons, with only a very limited parameter regime where convection can occur. Given the many unknowns (grain size, impurities etc.) it is challenging to draw strong conclusions about the behavior of icy moons . Nonetheless, the lack of convection in terrestrial ice sheets provides an important constraint on the dynamics of icy moons and models that explain convection of icy moons should also explain the lack of convection on terrestrial ice sheets.

Mid-infrared spectroscopy to better characterize icy moon surface compositions

NASA Astrophysics Data System (ADS)

Young, Cindy L.; Wray, James J.; Hand, Kevin P.; Poston, Michael; Carlson, Robert W.; Clark, Roger Nelson; Spencer, John R.; Jennings, Donald

2016-10-01

Previous spectroscopy work on icy moons has focused primarily on the visible and near-IR portion of the spectrum due to challenges presented by a low signal to noise ratio at the longer wavelengths. However, the mid-IR is the region of the strongest fundamental vibrations of many important types of molecules (e.g., organics) and has the potential to reveal unique compositional information [1]. We use the wealth of data that is now available from Cassini's Composite Infrared Spectrometer (CIRS) to average spectra over similar regions to improve the signal to noise, helping to reveal spectral features never before observed.Our initial work has already led to the detection and tentative laboratory identification of the first spectral features observed for any icy moon in the mid-IR [2]. On Iapetus' dark terrain, we found an emissivity feature at ~855 cm-1 and a possible doublet at 660 and 690 cm-1 that does not correspond to any known instrument artifacts. We attributed the 855 cm-1 feature to fine-grained silicates, similar to those found in dust on Mars and in meteorites, which are nearly featureless at shorter wavelengths [e.g., 3, 4]. Silicates on the dark terrains of Saturn's icy moons have been suspected for decades, but there have been no definitive detections until this work.We measured the vacuum, low temperature mid-IR spectra of various fine-grained powdered silicates, including Mg-rich serpentines, often present in meteorites. Some of these materials do have emissivity features near 855 cm-1 and exhibit a doublet. Presently, we are continuing to comb the CIRS icy moon database for spectral features (particularly focusing on the warmer surfaces in the Saturn system) and are performing further vacuum chamber measurements to experiment with more sample types and ice/sample mixtures to determine the impacts of changing conditions in the chamber on features. We are also working to understand how surface porosity and mixing with various darkening agents may

Applications of High Etendue Line-Profile Spectro-Polarimetry to the Study of the Atmospheric and Magnetospheric Environments of the Jovian Icy Moons

NASA Technical Reports Server (NTRS)

Harris, Walter M.; Roesler, Fred L.; Jaffel, Lotfi Ben; Ballester, Gilda E.; Oliversen, Ronald J.; Morgenthaler, Jeffrey P.; Mierkiewicz, Edwin

2003-01-01

Electrodynamic effects play a significant, global role in the state and energization of the Earth's ionosphere/magnetosphere, but even more so on Jupiter, where the auroral energy input is four orders of magnitude greater than on Earth. The Jovian magnetosphere is distinguished from Earth's by its rapid rotation rate and contributions from satellite atmospheres and internal plasma sources. The electrodynamic effects of these factors have a key role in the state and energization of the ionosphere-corona- plasmasphere system of the planet and its interaction with Io and the icy satellites. Several large scale interacting processes determine conditions near the icy moons beginning with their tenuous atmospheres produced from sputtering, evaporative, and tectonic/volcanic sources, extending out to exospheres that merge with ions and neutrals in the Jovian magnetosphere. This dynamic environment is dependent on a complex network of magnetospheric currents that act on global scales. Field aligned currents connect the satellites and the middle and tail magnetospheric regions to the Jupiter's poles via flux tubes that produce as bright auroral and satellite footprint emissions in the upper atmosphere. This large scale transfer of mass, momentum, and energy (e.g. waves, currents) means that a combination of complementary diagnostics of the plasma, neutral, and and field network must be obtained near simultaneously to correctly interpret the results. This presentation discusses the applicability of UV spatial heterodyne spectroscopy (SHS) to the broad study of this system on scales from satellite surfaces to Jupiter's aurora and corona.

Detection of an oxygen atmosphere on Jupiter's moon Europa.

PubMed

Hall, D T; Strobel, D F; Feldman, P D; McGrath, M A; Weaver, H A

1995-02-23

Europa, the second large satellite out from Jupiter, is roughly the size of Earth's Moon, but unlike the Moon, it has water ice on its surface. There have been suggestions that an oxygen atmosphere should accumulate around such a body, through reactions which break up the water molecules and form molecular hydrogen and oxygen. The lighter H2 molecules would escape from Europa relatively easily, leaving behind an atmosphere rich in oxygen. Here we report the detection of atomic oxygen emission from Europa, which we interpret as being produced by the simultaneous dissociation and excitation of atmospheric O2 by electrons from Jupiter's magnetosphere. Europa's molecular oxygen atmosphere is very tenuous, with a surface pressure about 10(-11) that of the Earth's atmosphere at sea level.

Technology for a Thermo-chemical Ice Penetrator for Icy Moons

NASA Astrophysics Data System (ADS)

Arenberg, Jonathan; Harpole, George; Zamel, James; Sen, Bashwar; Lee, Greg; Ross, Floyd; Retherford, Kurt D.

2016-10-01

The ability to place sensors or to take samples below the ice surface enables a wide variety of potential scientific investigations. Penetrating an ice cap can be accomplished via a mechanical drill, laser drill, kinetic impactor, or heated penetrator. This poster reports on the development of technology for the latter most option, namely a self-heated probe driven by an exothermic chemical reaction: a Thermo-chemical ice penetrator (TChIP). Our penetrator design employs a eutectic mix of alkali metals that produce an exothermic reaction upon contact with an icy surface. This reaction increases once the ice starts melting, so no external power is required. This technology is inspired by a classified Cold-War era program developed at Northrop Grumman for the US Navy. Terrestrial demonstration of this technology took place in the Arctic; however, this device cannot be considered high TRL for application at the icy moons of the solar system due to the environmental differences between Earth's Arctic and the icy moons. These differences demand a TChIP design specific to these cold, low mass, airless worlds. It is expected that this model of TChIP performance will be complex, incorporating all of the forces on the penetrator, gravity, the thermo-chemistry at the interface between penetrator and ice, and multi-phase heat and mass transport, and hydrodynamics. Our initial efforts are aimed at the development of a validated set of tools and simulations to predict the performance of the penetrator for both the environment found on these icy moons and for a terrestrial environment. The purpose of the inclusion of the terrestrial environment is to aid in model validation. Once developed and validated, our models will allow us to design penetrators for a specific scientific application on a specific body. This poster discusses the range of scientific investigations that are enabled by TChIP. We also introduce the development plan to advance TChIP to the point where it can be

Galilean Moons, Kepler's Third Law, and the Mass of Jupiter

NASA Astrophysics Data System (ADS)

Bates, Alan

2013-10-01

Simulations of physical systems are widely available online, with no cost, and are ready to be used in our classrooms. ,2 Such simulations offer an accessible tool that can be used for a range of interactive learning activities. The Jovian Moons Applet2 allows the user to track the position of Jupiter's four Galilean moons with a variety of viewing options. For this activity, data are obtained from the orbital period and orbital radii charts. Earlier experiments have used telescopes to capture the orbital motion of the Galilean moons,3 although observation of astronomical events and the measurement of quantities may be difficult to achieve due to a combination of cost, training, and observing conditions. The applet allows a suitable set of data to be generated and data analysis that verifies Kepler's third law of planetary motion, which leads to a calculated value for the mass of Jupiter.

Hubble Catches Jupiter's Largest Moon Going to the 'Dark Side'

NASA Image and Video Library

2017-12-08

Hubble Catches Jupiter's Largest Moon Going to the 'Dark Side' HST/WFPC2 Image of Jupiter and Ganymede Taken April 9, 2007 NASA's Hubble Space Telescope has caught Jupiter's moon Ganymede playing a game of "peek-a-boo." In this crisp Hubble image, Ganymede is shown just before it ducks behind the giant planet. Ganymede completes an orbit around Jupiter every seven days. Because Ganymede's orbit is tilted nearly edge-on to Earth, it routinely can be seen passing in front of and disappearing behind its giant host, only to reemerge later. Composed of rock and ice, Ganymede is the largest moon in our solar system. It is even larger than the planet Mercury. But Ganymede looks like a dirty snowball next to Jupiter, the largest planet in our solar system. Jupiter is so big that only part of its Southern Hemisphere can be seen in this image. Hubble's view is so sharp that astronomers can see features on Ganymede's surface, most notably the white impact crater, Tros, and its system of rays, bright streaks of material blasted from the crater. Tros and its ray system are roughly the width of Arizona. The image also shows Jupiter's Great Red Spot, the large eye-shaped feature at upper left. A storm the size of two Earths, the Great Red Spot has been raging for more than 300 years. Hubble's sharp view of the gas giant planet also reveals the texture of the clouds in the Jovian atmosphere as well as various other storms and vortices. Astronomers use these images to study Jupiter's upper atmosphere. As Ganymede passes behind the giant planet, it reflects sunlight, which then passes through Jupiter's atmosphere. Imprinted on that light is information about the gas giant's atmosphere, which yields clues about the properties of Jupiter's high-altitude haze above the cloud tops. This color image was made from three images taken on April 9, 2007, with the Wide Field Planetary Camera 2 in red, green, and blue filters. The image shows Jupiter and Ganymede in close to natural colors. For

Carbonic acid as a reserve of carbon dioxide on icy moons: The formation of carbon dioxide (CO{sub 2}) in a polar environment

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

Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni, E-mail: brantmj@hawaii.edu

Carbon dioxide (CO{sub 2}) has been detected on the surface of several icy moons of Jupiter and Saturn via observation of the ν{sub 3} band with the Near-Infrared Mapping Spectrometer on board the Galileo spacecraft and the Visible-Infrared Mapping Spectrometer on board the Cassini spacecraft. Interestingly, the CO{sub 2} band for several of these moons exhibits a blueshift along with a broader profile than that seen in laboratory studies and other astrophysical environments. As such, numerous attempts have been made in order to clarify this abnormal behavior; however, it currently lacks an acceptable physical or chemical explanation. We present amore » rather surprising result pertaining to the synthesis of carbon dioxide in a polar environment. Here, carbonic acid was synthesized in a water (H{sub 2}O)-carbon dioxide (CO{sub 2}) (1:5) ice mixture exposed to ionizing radiation in the form of 5 keV electrons. The irradiated ice mixture was then annealed, producing pure carbonic acid which was then subsequently irradiated, recycling water and carbon dioxide. However, the observed carbon dioxide ν{sub 3} band matches almost exactly with that observed on Callisto; subsequent temperature program desorption studies reveal that carbon dioxide synthesized under these conditions remains in solid form until 160 K, i.e., the sublimation temperature of water. Consequently, our results suggest that carbon dioxide on Callisto as well as other icy moons is indeed complexed with water rationalizing the shift in peak frequency, broad profile, and the solid state existence on these relatively warm moons.« less

2.7- to 4.1-micron spectrophotometry of icy satellites of Saturn and Jupiter

NASA Technical Reports Server (NTRS)

Lebofsky, L. A.; Feierberg, M. A.

1985-01-01

Spectrophotometry is presented in the 2.7-4.1 micrometer spectral region for icy satellites of Saturn (Tethys, Dione, Rhea, Iapetus and Hyperion) and Jupiter (Europa, Ganymede and Callisto). The 3.6-micrometer reflectance peak characteristic of fine-grained water ice is observed prominently on the satellites of Saturn, faintly on the leading side of Europa, and not at all on Ganymede, Callisto or the dark side of Iapetus. The spectral reflectances of these icy satellites may be affected by their equilibrium surface temperatures and magnetospheric effects.

Hubble Provides Infrared View of Jupiter's Moon, Ring, and Clouds

NASA Technical Reports Server (NTRS)

1997-01-01

Probing Jupiter's atmosphere for the first time, the Hubble Space Telescope's new Near Infrared Camera and Multi-Object Spectrometer (NICMOS) provides a sharp glimpse of the planet's ring, moon, and high-altitude clouds.

The presence of methane in Jupiter's hydrogen- and helium-rich atmosphere has allowed NICMOS to plumb Jupiter's atmosphere, revealing bands of high-altitude clouds. Visible light observations cannot provide a clear view of these high clouds because the underlying clouds reflect so much visible light that the higher level clouds are indistinguishable from the lower layer. The methane gas between the main cloud deck and the high clouds absorbs the reflected infrared light, allowing those clouds that are above most of the atmosphere to appear bright. Scientists will use NICMOS to study the high altitude portion of Jupiter's atmosphere to study clouds at lower levels. They will then analyze those images along with visible light information to compile a clearer picture of the planet's weather. Clouds at different levels tell unique stories. On Earth, for example, ice crystal (cirrus) clouds are found at high altitudes while water (cumulus) clouds are at lower levels.

Besides showing details of the planet's high-altitude clouds, NICMOS also provides a clear view of the ring and the moon, Metis. Jupiter's ring plane, seen nearly edge-on, is visible as a faint line on the upper right portion of the NICMOS image. Metis can be seen in the ring plane (the bright circle on the ring's outer edge). The moon is 25 miles wide and about 80,000 miles from Jupiter.

Because of the near-infrared camera's narrow field of view, this image is a mosaic constructed from three individual images taken Sept. 17, 1997. The color intensity was adjusted to accentuate the high-altitude clouds. The dark circle on the disk of Jupiter (center of image) is an artifact of the imaging system.

This image and other images and data received from the Hubble Space Telescope are

Identifying new surface constituents of icy moons using mid-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Young, Cindy L.; Wray, James J.; Hand, Kevin P.; Poston, Michael J.; Carlson, Robert W.; Clark, Roger N.; Spencer, John R.; Jennings, Donald E.

2015-11-01

Spectroscopic compositional studies of the icy satellites can help us to better understand the formation and evolution of material in the outer solar system. The spectral complexity of the Saturnian satellite system as seen in reflected visible light suggests additional complexity may be present at mid-infrared wavelengths from which unique compositional information can be gleaned [1]. In addition, the mid-infrared is the region of the stronger fundamental diagnostic vibrational modes of many compounds. However, Cassini Composite Infrared Spectrometer (CIRS) surface compositional studies have received little attention to date.We are exploring the suitability of mid-infrared spectroscopy for discovering non-H2O compounds on icy moon surfaces. On the dark terrain of Iapetus, we find an emissivity feature at ~855 cm-1 and a potential doublet at 660 and 690 cm-1 that do not correspond to any known instrument artifacts [2]. We attribute the 855 cm-1 feature to fine-grained silicates, similar to those found in dust on Mars and in meteorites, which are nearly featureless at shorter wavelengths [3]. Although silicates on the dark terrains of Saturn’s icy moons have been suspected for decades, there have been no definitive prior detections. Serpentines measured at ambient conditions have features near 855 cm-1 and 660 cm-1 [4]. However, peaks can shift depending on temperature, pressure, and grain size, so measurements at Iapetus-like conditions are necessary for more positive identifications [e.g., 5].We measured the vacuum, low temperature (125 K) spectra of various fine-grained powdered silicates. We find that some of these materials do have emissivity features near 855 cm-1 and match the doublet. Identifying a specific silicate would provide clues into the sources and sinks of the dark material in the Saturnian system. We report on our ongoing exploration of the CIRS icy moon dataset and plans for future measurements in JPL’s Icy Worlds Simulation Lab.[1] Flasar, F

Instrumentation for Testing Whether the Icy Moons of the Gas and Ice Giants Are Inhabited.

PubMed

Chela-Flores, Julian

2017-10-01

Evidence of life beyond Earth may be closer than we think, given that the forthcoming missions to the jovian system will be equipped with instruments capable of probing Europa's icy surface for possible biosignatures, including chemical biomarkers, despite the strong radiation environment. Geochemical biomarkers may also exist beyond Europa on icy moons of the gas giants. Sulfur is proposed as a reliable geochemical biomarker for approved and forthcoming missions to the outer solar system. Key Words: JUICE mission-Clipper mission-Geochemical biomarkers-Europa-Moons of the ice giants-Geochemistry-Mass spectrometry. Astrobiology 17, 958-961.

ESO Observations of New Moon of Jupiter

NASA Astrophysics Data System (ADS)

2000-08-01

Two astronomers, both specialists in minor bodies in the solar system, have performed observations with ESO telescopes that provide important information about a small moon, recently discovered in orbit around the solar system's largest planet, Jupiter. Brett Gladman (of the Centre National de la Recherche Scientifique (CNRS) and working at Observatoire de la Cote d'Azur, France) and Hermann Boehnhardt ( ESO-Paranal) obtained detailed data on the object S/1999 J 1 , definitively confirming it as a natural satellite of Jupiter. Seventeen Jovian moons are now known. The S/1999 J 1 object On July 20, 2000, the Minor Planet Center (MPC) of the International Astronomical Union (IAU) announced on IAU Circular 7460 that orbital computations had shown a small moving object, first seen in the sky in 1999, to be a new candidate satellite of Jupiter. The conclusion was based on several positional observations of that object made in October and November 1999 with the Spacewatch Telescope of the University of Arizona (USA). In particular, the object's motion in the sky was compatible with that of an object in orbit around Jupiter. Following the official IAU procedure, the IAU Central Bureau for Astronomical Telegrams designated the new object as S/1999 J 1 (the 1st candidate Satellite of Jupiter to be discovered in 1999). Details about the exciting detective story of this object's discovery can be found in an MPC press release and the corresponding Spacewatch News Note. Unfortunately, Jupiter and S/1999 J 1 were on the opposite side of the Sun as seen from the Earth during the spring of 2000. The faint object remained lost in the glare of the Sun in this period and, as expected, a search in July 2000 through all available astronomical data archives confirmed that it had not been seen since November 1999, nor before that time. With time, the extrapolated sky position of S/1999 J 1 was getting progressively less accurate. New observations were thus urgently needed to "recover

Jupiter’s moon Europa

NASA Image and Video Library

2014-01-24

This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The plumes, photographed by NASA’s Hubble’s Space Telescope Imaging Spectrograph, were seen in silhouette as the moon passed in front of Jupiter. Hubble’s ultraviolet sensitivity allowed for the features -- rising over 100 miles (160 kilometers) above Europa’s icy surface -- to be discerned. The water is believed to come from a subsurface ocean on Europa. The Hubble data were taken on January 26, 2014. The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions.

Physicochemical Requirements Inferred for Chemical Self-Organization Hardly Support an Emergence of Life in the Deep Oceans of Icy Moons

NASA Astrophysics Data System (ADS)

Pascal, Robert

2016-05-01

An approach to the origin of life, focused on the property of entities capable of reproducing themselves far from equilibrium, has been developed recently. Independently, the possibility of the emergence of life in the hydrothermal systems possibly present in the deep oceans below the frozen crust of some of the moons of Jupiter and Saturn has been raised. The present report is aimed at investigating the mutual compatibility of these alternative views. In this approach, the habitability concept deduced from the limits of life on Earth is considered to be inappropriate with regard to emerging life due to the requirement for an energy source of sufficient potential (equivalent to the potential of visible light). For these icy moons, no driving force would have been present to assist the process of emergence, which would then have had to rely exclusively on highly improbable events, thereby making the presence of life unlikely on these Solar System bodies, that is, unless additional processes are introduced for feeding chemical systems undergoing a transition toward life and the early living organisms.

Modeling Rock Alteration at the Water-Rock Interface of Icy Moons

NASA Astrophysics Data System (ADS)

Semprich, J.; Treiman, A. H.; Schwenzer, S. P.

2018-05-01

Alteration phases of a CM rock core are modeled with variations in fluid composition at the water-rock interface of icy moons. In the presence of H2O, CO2, CH4, and H2 serpentinization of the rock core is very likely at low pressures and 200–400 °C.

Far Ultraviolet Spectroscopy of Saturn's Icy Moon Rhea

NASA Astrophysics Data System (ADS)

Elowitz, Mark; Hendrix, Amanda; Mason, Nigel J.; Sivaraman, Bhalamurugan

2018-01-01

We present an analysis of spatially resolved, far-UV reflectance spectra of Saturn’s icy satellite Rhea, collected by the Cassini Ultraviolet Imaging Spectrograph (UVIS). In recent years ultraviolet spectroscopy has become an important tool for analysing the icy satellites of the outer solar system (1Hendrix & Hansen, 2008). Far-UV spectroscopy provides unique information about the molecular structure and electronic transitions of chemical species. Many molecules that are suspected to be present in the icy surfaces of moons in the outer solar system have broad absorption features due to electronic transitions that occur in the far-UV portion of the spectrum. The studies show that Rhea, like the other icy satellites of the Saturnian system are dominated by water-ice as evident by the 165-nm absorption edge, with minor UV absorbing contaminants. Far-UV spectra of several Saturnian icy satellites, including Rhea and Dione, show an unexplained weak absorption feature centered near 184 nm. To carry out the geochemical survey of Rhea’s surface, the UVIS observations are compared with vacuum-UV spectra of thin-ice samples measured in laboratory experiments. Thin film laboratory spectra of water-ice and other molecular compounds in the solid phase were collected at near-vacuum conditions and temperatures identical to those at the surface of Rhea. Comparison between the observed far-UV spectra of Rhea’s surface ice and modelled spectra based on laboratory absorption measurements of different non-water-ice compounds show that two possible chemical compounds could explain the 184-nm absorption feature. The two molecular compounds include simple chlorine molecules and hydrazine monohydrate. Attempts to explain the source(s) of these compounds on Rhea and the scientific implications of their possible discovery will be summarized.[1] Hendrix, A. R. & Hansen, C. J. (2008). Icarus, 193, pp. 323-333.

Jupiter's Hot, Mushy Moon

NASA Technical Reports Server (NTRS)

Taylor, G. Jeffrey

2003-01-01

Jupiter's moon Io is the most volcanically active body in the Solar System. Observations by instruments on the Galileo spacecraft and on telescopes atop Mauna Kea in Hawai'i indicate that lava flows on Io are surprisingly hot, over 1200 oC and possibly as much as 1300 oC; a few areas might have lava flows as hot as 1500 oC. Such high temperatures imply that the lava flows are composed of rock that formed by a very large amount of melting of Io's mantle. This has led Laszlo Keszthelyi and Alfred S. McEwen of the University of Arizona and me to reawaken an old hypothesis that suggests that the interior of Io is a partially-molten mush of crystals and magma. The idea, which had fallen out of favor for a decade or two, explains high-temperature hot spots, mountains, calderas, and volcanic plains on Io. If correct, Io gives us an opportunity to study processes that operate in huge, global magma systems, which scientists believe were important during the early history of the Moon and Earth, and possibly other planetary bodies as well. Though far from proven, the idea that Io has a ocean of mushy magma beneath its crust can be tested with measurements by future spacecraft.

The Moons of Jupiter / Journey to the Stars

NASA Astrophysics Data System (ADS)

Litwak, J.; Chatzichristou, E.

2017-09-01

The Moons of Jupiter/ Journey to the Stars uses the arts, most particularly theatre arts to inspire curiosity about science education. Using characters which include famous scientists as well as mythological figures, the project provokes thought and offers opportunity for discovery. The play and the subsequent creative teaching tools are accessible to scientists, artists and lay people in an out of the classroom.

Multi-Modal Active Perception for Autonomously Selecting Landing Sites on Icy Moons

NASA Technical Reports Server (NTRS)

Arora, A.; Furlong, P. M.; Wong, U.; Fong, T.; Sukkarieh, S.

2017-01-01

Selecting suitable landing sites is fundamental to achieving many mission objectives in planetary robotic lander missions. However, due to sensing limitations, landing sites which are both safe and scientifically valuable often cannot be determined reliably from orbit, particularly, in icy moon missions where orbital sensing data is noisy and incomplete. This paper presents an active perception approach to Entry Descent and Landing (EDL) which enables the lander to autonomously plan informative descent trajectories, acquire high quality sensing data during descent and exploit this additional information to select higher utility landing sites. Our approach consists of two components: probabilistic modeling of landing site features and approximate trajectory planning using a sampling based planner. The proposed framework allows the lander to plan long horizons paths and remain robust to noisy data. Results in simulated environments show large performance improvements over alternative approaches and show promise that our approach has strong potential to improve science return of not only icy moon missions but EDL systems in general.

Constraints on the nanoscale minerals on the surface of Saturnian icy moons

NASA Astrophysics Data System (ADS)

Srama, R.; Hsu, H.; Kempf, S.; Horanyi, M.

2011-12-01

Nano-phase iron particles embedded into the surfaces of Saturn's icy moons as well as in the ring material have been proposed to explain the infrared spectra obtained by Cassini VIMS. Because the continuous influx of interplanetary fast impactors into the Saturnian system erodes any exposed surface, a certain amount of the embedded nano-particles will be ejected into the Saturnian magnetosphere and speed up to velocities high enough to be detected by the Cassini dust detector CDA. Thus, the analysis of the so-called stream particles provides constraints on the amount and the composition of any nano-phase material within the surfaces of the icy moons. Nanoparticles registered by the Cassini dust detector are most likely composed of silica (SiO2). Their dynamical properties indicate that they are relics of E ring dust grains. In this talk we will show that the Cassini stream particle measurements provide strong constraints for the composition and size distribution of any embedded nano-material.

The Radio & Plasma Wave Investigation (RPWI) for JUICE - From Jupiter's Magnetosphere, through the Ice Shell, and into the Ocean of Ganymede

NASA Astrophysics Data System (ADS)

Bergman, J. E. S.; Wahlund, J.-E.; Witasse, O.; Cripps, V.

2017-09-01

The Radio & Plasma Wave Investigation (RPWI) on board the JUICE mission to Jupiter and its icy moons will enhance our understanding of magnetospheric and ionospheric physics processes in the Jupiter system, with emphasis on its icy moon Ganymede. By using innovative measurement techniques, such as passive ground penetrating radar, RPWI will also investigate the ice shell and try to measure its thickness. RPWI will as well help to detect and characterise the subsurface ocean of Ganymede. Thereby, RPWI will contribute to many high level science objectives, not foreseen when the instrument was proposed and selected for flight by ESA. The close collaboration with the two other in situ payload teams (JMAG and PEP), on ground and on board the JUICE spacecraft, will further enhance the value of our combined data sets.

Galilean Moons, Kepler's Third Law, and the Mass of Jupiter

ERIC Educational Resources Information Center

Bates, Alan

2013-01-01

Simulations of physical systems are widely available online, with no cost, and are ready to be used in our classrooms. Such simulations offer an accessible tool that can be used for a range of interactive learning activities. The Jovian Moons Apple allows the user to track the position of Jupiter's four Galilean moons with a variety of…

Europa's Icy Shell: A Bridge Between Its Surface and Ocean

NASA Technical Reports Server (NTRS)

Schenk, Paul; Mimmo, Francis; Prockter, Louise

2004-01-01

Europa, a Moon-sized, ice-covered satellite of Jupiter, is second only to Mars in its astrobiological potential. Beneath the icy surface, an ocean up to 150 km deep is thought to exist, providing a potential habitat for life,and a tempting target for future space missions. The Galileo mission to the Jovian system recently ended, but there are already long-range plans to send much more capable spacecraft,such as the proposed Jupiter Icy Moons Orbiter (JIMO), to take a closer look at Europa and her siblings, Ganymede and Callisto, some time in the next two decades. Europak outer icy shell is the only interface between this putative ocean and the surface, but many aspects of this shell are presently poorly understood; in particular, its composition, thickness, deformational history, and mechanical properties. To discuss the ice shell and our current understanding of it, 78 scientists from the terrestrial and planetary science communities in the United States and Europe gathered for a 3-day workshop hosted by the Lunar and Planetary Institute in Houston in February. A key goal was to bring researchers from disparate disciplines together to discuss the importance and limitations of available data on Europa with a post-Galileo perspective. The workshop featured 2 days of reviews and contributed talks on the composition, physical properties, stratigraphy, tectonics, and future exploration of the ice shell and underlying ocean. The final morning included an extended discussion period, moderated by a panel of noted experts, highlighting outstanding questions and areas requiring future research.

Two Moons Meet over Jupiter

NASA Technical Reports Server (NTRS)

2007-01-01

This beautiful image of the crescents of volcanic Io and more sedate Europa was snapped by New Horizons' color Multispectral Visual Imaging Camera (MVIC) at 10:34 UT on March 2, 2007, about two days after New Horizons made its closest approach to Jupiter.

The picture was one of a handful of the Jupiter system that New Horizons took primarily for their artistic, rather than scientific value. This particular scene was suggested by space enthusiast Richard Hendricks of Austin, Texas, in response to an Internet request by New Horizons scientists for evocative, artistic imaging opportunities at Jupiter.

This image was taken from a range of 4.6 million kilometers (2.8 million miles) from Io and 3.8 million kilometers (2.4 million miles) from Europa. Although the moons appear close in this view, a gulf of 790,000 kilometers (490,000 miles) separates them. The night side of Io is illuminated here by light reflected from Jupiter, which is out of the frame to the right. Europa's night side is completely dark, in contrast to Io, because that side of Europa faces away from Jupiter.

Here, Io steals the show with its beautiful display of volcanic activity. Three volcanic plumes are visible. Most conspicuous is the enormous 300-kilometer (190-mile) -high plume from the Tvashtar volcano at the 11 o'clock position on Io's disk. Two much smaller plumes are barely visible: one from the volcano Prometheus, at the 9 o'clock position on the edge of Io's disk, and one from the volcano Amirani, seen between Prometheus and Tvashtar along Io's terminator (the line dividing day and night). The plumes appear blue because of the scattering of light by tiny dust particles ejected by the volcanoes, similar to the blue appearance of smoke. In addition, the contrasting red glow of hot lava can be seen at the source of the Tvashtar plume.

The images are centered at 1 degree north, 60 degrees west on Io, and 0 degrees north, 149 degrees west on Europa. The color in this

Compositional Remote Sensing of Icy Planets and Satellites Beyond Jupiter

NASA Technical Reports Server (NTRS)

Roush, T. L.

2002-01-01

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

What Would Constitute Evidence for Life on Icy Moons?

NASA Technical Reports Server (NTRS)

Pohorille, A.; Hoehler, T. M.

2017-01-01

For the first time since Viking, NASA is considering missions that would include life detection as a primary objective, making it critical to develop and evaluate a diverse set of strategies for seeking evidence of life. The central question is: what should be the target of our search that, if found, would constitute a near-certain evidence for life? Since life on icy moons might be quite different from terrestrial life, we should concentrate on features of biological systems that are considered universal and are unlikely to emerge through abiotic means.

Looking for planetary moons in the spectra of distant Jupiters.

PubMed

Williams, D M; Knacke, R F

2004-01-01

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

PHOTO ILLUSTRATION OF COMET P/SHOEMAKER-LEVY 9 and PLANET JUPITER

NASA Technical Reports Server (NTRS)

2002-01-01

This is a composite photo, assembled from separate images of Jupiter and comet P/Shoemaker-Levy 9, as imaged by the Wide Field and Planetary Camera-2 (WFPC-2), aboard NASA's Hubble Space Telescope (HST). Jupiter was imaged on May 18, 1994, when the giant planet was at a distance of 420 million miles (670 million km) from Earth. This 'true-color' picture was assembled from separate HST exposures in red, blue, and green light. Jupiter's rotation between exposures creates the blue and red fringe on either side of the disk. HST can resolve details in Jupiter's magnificent cloud belts and zones as small as 200 miles (320 km) across (wide field mode). This detailed view is only surpassed by images from spacecraft that have traveled to Jupiter. The dark spot on the disk of Jupiter is the shadow of the inner moon Io. This volcanic moon appears as an orange and yellow disk just to the upper right of the shadow. Though Io is approximately the size of Earth's Moon (but 2,000 times farther away), HST can resolve surface details. When the comet was observed on May 17, its train of 21 icy fragments stretched across 710 thousand miles (1.1 million km) of space, or 3 times the distance between Earth and the Moon. This required six WFPC exposures along the comet train to include all the nuclei. The image was taken in red light. The apparent angular size of Jupiter relative to the comet, and its angular separation from the comet when the images were taken, have been modified for illustration purposes. Credit: H.A. Weaver, T.E. Smith (Space Telescope Science Institute) and J.T. Trauger, R.W. Evans (Jet Propulsion Laboratory), and NASA

Study of the Jupiter X-ray imaging spectrometer on JMO

NASA Astrophysics Data System (ADS)

Kimura, T.; Ezoe, Y.; Kasahara, S.; Miyoshi, Y.; Yamazaki, A.; Fujimoto, M.; JMO X-ray Experiment Team

2011-12-01

In 2000's, the new generation X-ray observatories (Chandra, XMM-Newton and Suzaku) have revealed various new X-ray phenomena in the Jupiter system. The detected objects include Jupiter's aurorae, disk (middle and low-latitude emission), Io, Europa, the Io Plasma Torus, and radiation belts. For example, Jupiter's aurorae emit time variable X-rays via bremsstrahlung by keV electrons and charge exchange by MeV ions (Gladstone et al. 2002 Nature). A diffuse X-ray emission associated with the Jupiter's radiation belts suggests an inverse Compton scattering of tens MeV electrons (Ezoe et al. 2010 ApJ). Hence, the X-ray emission can be a unique diagnostic tool to investigate key fundamental problems on the Jupiter system such as the relativistic particle acceleration and the Jupiter-satellite reaction. However, since these observations have been done with the X-ray astronomy satellites orbiting the Earth, the photon statistics of X-ray spectra and light curves, and the angular resolution of X-ray images were severely limited. In this context, we have started to study design of an X-ray imaging spectrometer for JMO (Jupiter Magnetospheric Orbiter) which is expected to collaborate with international Jupiter exploration mission JUICE (JUpiter ICy moon Explorer). JUICE is originally EJSM (Europa Jupiter System Mission) but recently renamed JUICE as ESA-lead mission, which is proposed to be launched in 2020's. It consists of one main flight element developed by ESA to explore icy moons of Jupiter, and JMO by JAXA is expected to perform high-latitude (10-30 deg inclination) measurements of the Jupiter system and overview the magnetospheric activities. The in-situ measurements by EJSM JMO provide us with an unprecedented opportunity to observe Jupiter with extremely high photon statistics, high time and angular resolution. To realize the in-situ X-ray instrument for EJSM JMO, stringent mass and power limitations must be fulfilled. Furthermore, the radiation and the contamination

Two-Body Approximations in the Design of Low-Energy Transfers Between Galilean Moons

NASA Astrophysics Data System (ADS)

Fantino, Elena; Castelli, Roberto

Over the past two decades, the robotic exploration of the Solar System has reached the moons of the giant planets. In the case of Jupiter, a strong scientific interest towards its icy moons has motivated important space missions (e.g., ESAs' JUICE and NASA's Europa Mission). A major issue in this context is the design of efficient trajectories enabling satellite tours, i.e., visiting the several moons in succession. Concepts like the Petit Grand Tour and the Multi-Moon Orbiter have been developed to this purpose, and the literature on the subject is quite rich. The models adopted are the two-body problem (with the patched conics approximation and gravity assists) and the three-body problem (giving rise to the so-called low-energy transfers, LETs). In this contribution, we deal with the connection between two moons, Europa and Ganymede, and we investigate a two-body approximation of trajectories originating from the stable/unstable invariant manifolds of the two circular restricted three body problems, i.e., Jupiter-Ganymede and Jupiter-Europa. We develop ad-hoc algorithms to determine the intersections of the resulting elliptical arcs, and the magnitude of the maneuver at the intersections. We provide a means to perform very fast and accurate evaluations of the minimum-cost trajectories between the two moons. Eventually, we validate the methodology by comparison with numerical integrations in the three-body problem.

Hemispheric and Topographic Asymmetry of Magnetospheric Particle Irradiation for Icy Moon Surfaces

NASA Technical Reports Server (NTRS)

Cooper, John F.; Sturner, S. J.

2007-01-01

All surfaces of icy moons without significant atmospheres, i.e. all except Titan in the giant planet systems, are irradiated by hot plasma and more energetic charged particles from the local magnetospheric environments. This irradiation can significantly impact the chemical composition, albedo, and detectable presence of signs of life on the sensible surfaces, while also limiting lifetimes and science operations of orbital spacecraft for extreme radiation environments as at Europa. Planning of surface remote sensing and lander operations, and interpretation of remote sensing and in-situ measurements, should include consideration of natural shielding afforded by the body of the moon, by any intrinsic or induced magnetic fields as at Ganyrnede, and by topographic structures.

Multi-fluid MHD simulations of Europa's interaction with Jupiter's magnetosphere

NASA Astrophysics Data System (ADS)

Harris, C. D. K.; Jia, X.; Slavin, J. A.; Rubin, M.; Toth, G.

2017-12-01

Several distinct physical processes generate the interaction between Europa, the smallest of Jupiter's Galilean moons, and Jupiter's magnetosphere. The 10˚ tilt of Jupiter's dipole causes time varying magnetic fields at Europa's orbit which interact with Europa's subsurface conducting ocean to induce magnetic perturbations around the moon. Jovian plasma interacts with Europa's icy surface to sputter off neutral particles, forming a tenuous exosphere which is then ionized by impact and photo-ionization to form an ionosphere. As jovian plasma flows towards the moon, mass-loading and interaction with the ionosphere slow the flow, producing magnetic perturbations that propagate along the field lines to form an Alfvén wing current system, which connects Europa to its bright footprint in Jupiter's ionosphere. The Galileo mission has shown that the plasma interaction generates significant magnetic perturbations that obscure signatures of the induced field from the subsurface ocean. Modeling the plasma-related perturbations is critical to interpreting the magnetic signatures of Europa's induction field, and therefore to magnetic sounding of its interior, a central goal of the upcoming Europa Clipper mission. Here we model the Europa-Jupiter interaction with multi-fluid magnetohydrodynamic simulations to understand quantitatively how these physical processes affect the plasma and magnetic environment around the moon. Our model separately tracks the bulk motion of three different ion fluids (exospheric O2+, O+, and magnetospheric O+), and includes sources and losses of mass, momentum and energy to each of the ion fluids due to ionization, charge-exchange and recombination. We include calculations of the electron temperature allowing for field-aligned electron heat conduction, and Hall effects due to differential ion-electron motion. Compared to previous simulations, this multi-fluid model allows us to more accurately determine the precipitation flux of jovian plasma to

Estimation of a melting probe's penetration velocity range to reach icy moons' subsurface ocean

NASA Astrophysics Data System (ADS)

Erokhina, Olga; Chumachenko, Eugene

2014-05-01

In modern space science one of the actual branches is icy satellites explorations. The main interest is concentrated around Jovian's moons Europa and Ganymede, Saturn's moons Titan and Enceladus that are covered by thick icy layer according to "Voyager1", "Voyager2", "Galileo" and "Cassini" missions. There is a big possibility that under icy shell could be a deep ocean. Also conditions on these satellites allow speculating about possible habitability, and considering these moons from an astrobiological point of view. One of the possible tasks of planned missions is a subsurface study. For this goal it is necessary to design special equipment that could be suitable for planetary application. One of the possible means is to use a melting probe which operates by melting and moves by gravitational force. Such a probe should be relatively small, should not weight too much and should require not too much energy. In terrestrial case such kind of probe has been successfully used for glaciers study. And it is possible to extrapolate the usage of such probe to extraterrestrial application. One of the tasks is to estimate melting probe's penetration velocity. Although there are other unsolved problems such as analyzing how the probe will move in low gravity and low atmospheric pressure; knowing whether hole will be closed or not when probe penetrate thick enough; and considering what order could be a penetration velocity. This study explores two techniques of melting probe's movement. One of them based on elasto-plastic theory and so-called "solid water" theory, and other one takes phase changing into account. These two techniques allow estimating melting probe's velocity range and study whole process. Based on these technique several cases of melting probe movement were considered, melting probe's velocity range estimated, influence of different factors studied and discussed and an easy way to optimize parameters of the melting probe proposed.

Overview of the Project Prometheus Program

NASA Technical Reports Server (NTRS)

Burdick, G. M.

2003-01-01

This presentation will give an overview of the Project Prometheus Program (PPP, formerly the Nuclear Systems Initiative, NSI) and the Jupiter Icy Moons Orbiter (JIMO) Project (a component of PPP), a mission to the three icy Galilean moons of Jupiter.

Roemer Redux: A Virtual Observational Exercise on Jupiter's Moons and the Speed of Light from Project CLEA

NASA Astrophysics Data System (ADS)

Dabrowski, Jan Paul; Snyder, G. A.; Marschall, L. A.

2009-01-01

Project CLEA announces a new laboratory exercise which allows students to determine the speed of light by timing eclipses of Jupiter's moon Io. The experiment is similar to Ole Roemer's classic 17th Century work which established, for the first time, that light did not travel through space instantaneously. Students view a simulated telescopic view of Jupiter and its satellites, similar to that used in the CLEA exercise, The Revolution of the Moons of Jupiter. After identifying Io, they record the precise time when the moon enters Jupiter's shadow at a date about two months after conjunction. Using the recorded time of this eclipse and the known period of Io, students predict the time of an eclipse near opposition and then record the observed time of that eclipse. The discrepancy between the predicted and observed times, along with the difference in the distance between Earth and Jupiter at the two eclipses yields a value of the speed of light accurate to about 10%. Software provided with the exercise enables students to calculate predicted times and Earth/Jupiter distances, as well as to analyze the time discrepancy and to visualize the logic of the analysis. A student manual, including historical and scientific background of the exercise is provided. Our poster will present examples of the screens and manuals for the exercise and will discuss the limits of accuracy of the method and sources of error. For further information on CLEA exercises, please visit http://www.gettysburg.edu/ marschal/clea/CLEAhome.html This research was sponsored by the National Science Foundation and Gettysburg College.

Heat transport in the high-pressure ice mantle of large icy moons

NASA Astrophysics Data System (ADS)

Choblet, Gael; Tobie, Gabriel; Sotin, Christophe; Kalousova, Klara; Grasset, Olivier

2017-04-01

While the existence of a buried ocean sandwiched between surface ice and high-pressure (HP) polymorphs of ice emerges as the most plausible structure for the hundreds-of-kilometers thick hydrospheres within large icy moons of the Solar System (Ganymede, Callisto, Titan), little is known about the thermal structure of the deep HP ice mantle and its dynamics, possibly involving melt production and extraction. This has major implications for the thermal history of these objects as well as on the habitability of their ocean as the HP ice mantle is presumed to limit chemical transport from the rock component to the ocean. Here, we describe 3D spherical simulations of subsolidus thermal convection tailored to the specific structure of the HP ice mantle of large icy moons. Melt production is monitored and melt transport is simplified by assuming instantaneous extraction to the ocean above. The two controlling parameters for these models are the rheology of ice VI and the heat flux from the rock core. Reasonable end-members are considered for both parameters as disagreement remains on the former (especially the pressure effect on viscosity) and as the latter is expected to vary significantly during the moon's history. We show that the heat power produced by radioactive decay within the rock core is mainly transported through the HP ice mantle by melt extraction to the ocean, with most of the melt produced directly above the rock/water interface. While the average temperature in the bulk of the HP ice mantle is always relatively cool when compared to the value at the interface with the rock core (˜ 5 K above the value at the surface of the HP ice mantle), maximum temperatures at all depths are close to the melting point, often leading to the interconnection of a melt path via hot convective plume conduits throughout the HP ice mantle. Overall, we predict long periods of time during these moons' history where water generated in contact with the rock core is transported to

Heat transport in the high-pressure ice mantle of large icy moons

NASA Astrophysics Data System (ADS)

Choblet, G.; Tobie, G.; Sotin, C.; Kalousová, K.; Grasset, O.

2017-03-01

While the existence of a buried ocean sandwiched between surface ice and high-pressure (HP) polymorphs of ice emerges as the most plausible structure for the hundreds-of-kilometers thick hydrospheres within large icy moons of the Solar System (Ganymede, Callisto, Titan), little is known about the thermal structure of the deep HP ice mantle and its dynamics, possibly involving melt production and extraction. This has major implications for the thermal history of these objects as well as on the habitability of their ocean as the HP ice mantle is presumed to limit chemical transport from the rock component to the ocean. Here, we describe 3D spherical simulations of subsolidus thermal convection tailored to the specific structure of the HP ice mantle of large icy moons. Melt production is monitored and melt transport is simplified by assuming instantaneous extraction to the ocean above. The two controlling parameters for these models are the rheology of ice VI and the heat flux from the rock core. Reasonable end-members are considered for both parameters as disagreement remains on the former (especially the pressure effect on viscosity) and as the latter is expected to vary significantly during the moon's history. We show that the heat power produced by radioactive decay within the rock core is mainly transported through the HP ice mantle by melt extraction to the ocean, with most of the melt produced directly above the rock/water interface. While the average temperature in the bulk of the HP ice mantle is always relatively cool when compared to the value at the interface with the rock core (∼ 5 K above the value at the surface of the HP ice mantle), maximum temperatures at all depths are close to the melting point, often leading to the interconnection of a melt path via hot convective plume conduits throughout the HP ice mantle. Overall, we predict long periods of time during these moons' history where water generated in contact with the rock core is transported to

Breaking Ice 2: A rift system on the Ross Ice Shelf as an analog for tidal tectonics on icy moons

NASA Astrophysics Data System (ADS)

Brunt, K. M.; Hurford, T., Jr.; Schmerr, N. C.; Sauber, J. M.; MacAyeal, D. R.

2016-12-01

Ice shelves are the floating regions of the polar ice sheets. Outside of the influence of the narrow region of their grounding zone, they are fully hydrostatic and strongly influenced by the ocean tides. Recent observational and modeling studies have assessed the effect of tides on ice shelves, including: the tidal influence on the ice-shelf surface height, which changes by as much as 6 to 7 m on the southern extreme of the Ronne-Filchner Ice Shelf; the tidal modulation of the ice-shelf horizontal flow velocities, which changes the mean ice-flow rate by as much as two fold on the Ross Ice Shelf; and the tidal contribution to fracture and rift propagation, which eventually leads to iceberg calving. Here, we present the analysis of 16 days of continuous GPS data from a rift system near the front of the Ross Ice Shelf. While the GPS sites were installed for a different scientific investigation, and not optimized to assess tidal rifting mechanics, they provide a first-order sense of the tidal evolution of the rift system. These analyses can be used as a terrestrial analog for tidal activity on icy satellites, such as Europa and Enceladus, moons of Jupiter and Saturn, respectively. Using remote sensing and modeling of the Ross Ice Shelf rift system, we can investigate the geological processes observed on icy satellites and advance modeling efforts of their tidal-tectonic evolution.

MAJIS (Moons and Jupiter Imaging Spectrometer): the VIS-NIR imaging spectrometer of the JUICE mission

NASA Astrophysics Data System (ADS)

Langevin, Yves; Piccioni, Giuseppe; Dumesnil, Cydalise; Filacchione, Gianrico; Poulet, Francois; MAJIS Team

2016-10-01

MAJIS is the VIS-NIR imaging spectrometer of JUICE. This ambitious mission of ESA's « cosmic vision » program will investigate Jupiter and its system with a specific focus on Ganymede. After a tour of more than 3 years including 2 fly-bys of Europa and up to 20 flybys of Ganymede and Callisto, the end of the nominal mission will be dedicated to an orbital phase around Ganymede with 120 days in a near-circular, near-polar orbit at an altitude of 5000 km and 130 days in a circular near-polar orbit at an altitude of 500 km. MAJIS will adress 17 of the 19 primary science objectives of JUICE, investigating the surface and exosphere of the Galilean satellites (Ganymede during the orbital phase, Europa and Callisto during close flybys, Io from a minimum distance of 570,000 km), the atmosphere / exosphere of Jupiter, small satellites and rings, and their role as sources and sinks of particles in the Jupiter magnetosphere.The main technical characteristics are the following:Spectral range : 0.5 - 5.7 µm with two overlapping channels (VIS-NIR : 0.5 - 2.35 µm ; IR : 2.25 - 5.7 µm)Spatial resolution : 0.125 to 0.15 mradSpectral sampling (VIS-NIR channel) : 2.9 to 3.45 nmSpectral sampling (IR channel) : 5.4 to 6.45 nmThe spectral and spatial resolution will be finalized in october 2016 after the selection of the MAJIS detectors.Passive cooling will provide operating temperatures < 130 K (VIS-NIR) and < 90 K (IR) so as to limit the impact of dark current on performances.The SNR as determined from the photometric model and the noise model will be larger than 100 over most of the spectral range except for high resolution observations of icy moons at low altitude due to limitations on the integration time even with motion compensation provided by a scanner and for exospheric observations due to intrinsic low signal levels.

Positional Catalogues of Saturn's and Jupiter's Moons

NASA Astrophysics Data System (ADS)

Yizhakevych, O.; Andruk, V.; Pakuliak, L.; Lukianchuk, V.; Shatokhina, S.

In the framework of the UkrVO national project (http://ukr-vo.org/) we have started the processing of photographic observations of Saturn's (S1-S8) and Jupiter's (J6-J8) moons. Observations were conducted during 1961-1993 with three astrographs DLFA, DWA, DAZ and Z600 reflector. Plate images were digitized as tif-files with commercial scanners. Image processing was carried out by specific software package in the LINUX-MIDAS-ROMAFOT environment with Tycho2 as reference. The software was developed at the MAO NASU. Obtained positions of objects were compared with theoretically predicted ones in IMCCE (Paris) (www.imcce.fr/sat) online. Rms error of divergence between observed and calculated positions is of 0.20' - 0.35'.

Planetary Protection for future missions to Europa and other icy moons: the more things change...

NASA Astrophysics Data System (ADS)

Conley, C. A.; Race, M.

2007-12-01

NASA maintains a planetary protection policy regarding contamination of extraterrestrial bodies by terrestrial microorganisms and organic compounds, and sets limits intended to minimize or prevent contamination resulting from spaceflight missions. Europa continues to be a high priority target for astrobiological investigations, and other icy moons of the outer planets are becoming increasingly interesting as data are returned from current missions. In 2000, a study was released by the NRC that provided recommendations on preventing the forward contamination of Europa. This study addressed a number of issues, including cleaning and sterilization requirements, the applicability of protocols derived from Viking and other missions to Mars, and the need to supplement spore based culture methods in assessing spacecraft bioload. The committee also identified a number of future studies that would improve knowledge of Europa and better define issues related to forward contamination of that body. The standard recommended by the 2000 study and adopted by NASA uses a probabilistic approach, such that spacecraft sent to Europa must demonstrate a probability less than 10-4 per mission of contaminating an europan ocean with one viable terrestrial organism. A number of factors enter into the equation for calculating this probability, including at least bioload at launch, probability of survival during flight, probability of reaching the surface of Europa, and probability of reaching an europan ocean. Recently, the NASA Planetary Protection Subcommittee of the NASA Advisory Council has recommended that the probabilistic approach recommended for Europa be applied to all outer planet icy moons, until another NRC study can be convened to reevaluate the issues in light of recent data. This presentation will discuss the status of current and anticipated planetary protection considerations for missions to Europa and other icy moons.

High energy electron sintering of icy regoliths: Formation of the PacMan thermal anomalies on the icy Saturnian moons

NASA Astrophysics Data System (ADS)

Schaible, M. J.; Johnson, R. E.; Zhigilei, L. V.; Piqueux, S.

2017-03-01

The so-called 'PacMan' features on the leading hemispheres of the icy Saturnian moons of Mimas, Tethys and Dione were initially identified as anomalous optical discolorations and subsequently shown to have greater thermal inertia than the surrounding regions. The shape of these regions matches calculated deposition contours of high energy plasma electrons moving opposite to the moon's orbital direction, thus suggesting that electron interactions with the grains produce the observed anomalies. Here, descriptions of radiation-induced diffusion processes are given, and various sintering models are considered to calculate the rate of increase in the contact volume between grains in an icy regolith. Estimates of the characteristic sintering timescale, i.e. the time necessary for the thermal inertia to increase from that measured outside the anomalous regions to that within, are given for each of the moons. Since interplanetary dust particle (IDP) impact gardening and E-ring grain infall would be expected to mix the regolith and obscure the effects of high energy electrons, sintering rates are compared to rough estimates of the impact-induced resurfacing rates. Estimates of the sintering timescale determined by extrapolating laboratory measurements are below ∼0.03 Myr, while the regolith renewal timescales are larger than ∼0.1 Myr, thus indicating that irradiation by the high energy electrons should be sufficient to form stable thermal anomalies. More detailed models developed for sintering of spherical grains are able to account for the radiation-induced anomalies on Mimas and Tethys only if the regoliths on those bodies are relatively compact and composed of small (≲ 5 μm) grains or grain aggregates, and/or the grains are highly non-spherical with surface defect densities in the inter-grain contact regions that are much higher than expected for crystalline water ice grains at thermal equilibrium. These results are consistent with regolith thermal conductivity

The Europa Jupiter System Mission

NASA Astrophysics Data System (ADS)

Hendrix, A. R.; Clark, K.; Erd, C.; Pappalardo, R.; Greeley, R. R.; Blanc, M.; Lebreton, J.; van Houten, T.

2009-05-01

Europa Jupiter System Mission (EJSM) will be an international mission that will achieve Decadal Survey and Cosmic Vision goals. NASA and ESA have concluded a joint study of a mission to Europa, Ganymede and the Jupiter system with orbiters developed by NASA and ESA; contributions by JAXA are also possible. The baseline EJSM architecture consists of two primary elements operating in the Jovian system: the NASA-led Jupiter Europa Orbiter (JEO), and the ESA-led Jupiter Ganymede Orbiter (JGO). The JEO mission has been selected by NASA as the next Flagship mission to the out solar system. JEO and JGO would execute an intricately choreographed exploration of the Jupiter System before settling into orbit around Europa and Ganymede, respectively. JEO and JGO would carry eleven and ten complementary instruments, respectively, to monitor dynamic phenomena (such as Io's volcanoes and Jupiter's atmosphere), map the Jovian magnetosphere and its interactions with the Galilean satellites, and characterize water oceans beneath the ice shells of Europa and Ganymede. EJSM will fully addresses high priority science objectives identified by the National Research Council's (NRC's) Decadal Survey and ESA's Cosmic Vision for exploration of the outer solar system. The Decadal Survey recommended a Europa Orbiter as the highest priority outer planet flagship mission and also identified Ganymede as a highly desirable mission target. EJSM would uniquely address several of the central themes of ESA's Cosmic Vision Programme, through its in-depth exploration of the Jupiter system and its evolution from origin to habitability. EJSM will investigate the potential habitability of the active ocean-bearing moons Europa and Ganymede, detailing the geophysical, compositional, geological and external processes that affect these icy worlds. EJSM would also explore Io and Callisto, Jupiter's atmosphere, and the Jovian magnetosphere. By understanding the Jupiter system and unraveling its history, the

Exploring Jupiter's icy moons with old techniques and big facilities - new insights on sulfuric acid hydrates

NASA Astrophysics Data System (ADS)

Maynard-Casely, H. E.; Avdeev, M.; Brand, H.; Wallwork, K.

2013-12-01

Sulfuric acid hydrates have been proposed to be abundant on the surface of Europa [1], and hence would be important planetary forming materials for this moon and its companions Ganymede and Callisto. Understanding of the surface features and subsurface of these moons could be advanced by firmer knowledge of the icy materials that comprise them [2], insight into which can be drawn from firmer knowledge of physical properties and phase behaviour of the candidate materials. We wish to present results from a study that started with the question ';What form of sulfuric acid hydrate would form on the surface of Europa'. The intrinsic hydrogen-domination of planetary ices, makes studying these materials with laboratory powder diffraction very challenging. Insights into their crystalline phase behavior and the extraction of a number of thermal and mechanical properties is often only accessible with high-flux synchrotron x-ray diffraction and utilization of the large scattering cross section with neutron diffraction. We have used the Powder Diffraction beamline at Australian synchrotron [4] and the Echidna (High-resolution neutron powder diffraction) instrument of the Australian Nuclear Science and Technology Organization, [5] to obtain an number of new insights into the crystalline phases formed from sulfruic acid and water mixtures. These instruments have enabled the discovery a new water-rich sulfuric acid hydrate form [6], improved structural characterisation of existing forms [7] and a charting the phase diagram of this fundamental binary system [8]. This has revealed exciting potential for understanding more about the surface of Europa from space, perhaps even providing a window into its past. [1] Carlson, R.W., R.E. Johnson, and M.S. Anderson, Science, 1999. 286(5437): p. 97-99. [2] Fortes, A.D. and M. Choukroun. Space Sci Rev, 2010. 153(1-4): p. 185-218. [3] Blake, D., et al., Space Sci Rev,, 2012. 170(1-4): p. 341-399. [4] Wallwork, K.S., Kennedy B. J. and Wang, D

Spatial distribution of polarization over the disks of Venus, Jupiter, Saturn, and the moon

NASA Technical Reports Server (NTRS)

Fountain, J. W.

1974-01-01

The method of photographic subtraction, which superposes positive and negative photographs taken with the analyzer rotated through 90 deg, is used to analyze polarization photographs of Venus, Jupiter, Saturn, and the moon. For Venus, near 90 deg phase angle, variation in polarization in ultraviolet light appears to correspond generally with the position of the cloud markings. The northern hemisphere of Saturn shows higher polarization in blue light than does the rest of the planet. The polarization of the moon is shown to deviate significantly from Umov's law for reciprocity of polarization and reflectivity in certain regions.

Cosmic ion bombardment of the icy moons of Jupiter

NASA Astrophysics Data System (ADS)

Strazzulla, G.

2011-05-01

A large number of experiments have been performed in many laboratories in the world with the aim to investigate the physico-chemical effects induced by fast ions irradiating astrophysical relevant materials. The laboratory in Catania (Italy) has given a contribution to some experimental works. In this paper I review the results of two class of experiments performed by the Catania group, namely implantation of reactive (H+, C+, N+, O+ and S+) ions in ices and the ion irradiation induced synthesis of molecules at the interface between water ice and carbonaceous or sulfurous solid materials. The results, discussed in the light of some questions concerning the surfaces of the Galilean moons, contribute to understand whether minor molecular species (CO2, SO2, H2SO4, etc.) observed on those objects are endogenic i.e. native from the satellite or are produced by exogenic processes, such as ion implantation.The results indicate that:C-ion implantation is not the dominant formation mechanism of CO2 on Europa, Ganimede and Callisto.Implantation of sulfur ions into water ice produces hydrated sulfuric acid with high efficiency such to give a very important contribution to the sulfur cycle on the surface of Europa and other satellites.Implantation of protons into carbon dioxide produces some species containing the projectile (H2CO3, and O-H in poly-water).Implantation of protons into sulfur dioxide produces SO3, polymers, and O3 but not H-S bonds.Water ice has been deposited on refractory carbonaceous materials: a general finding is the formation of a noteworthy quantity of CO2. We suggest that this is the primary mechanism to explain the presence of carbon dioxide on the surfaces of the Galilean satellites.Water ice has been deposited on refractory sulfurous materials originating from SO2 or H2S irradiation. No evidence for an efficient synthesis of SO2 has been found.

Jupiter's and Saturn's ice moons: geophysical aspects and opportunities of geophysical survey of the planetary geoelectrical markers and oreols of the subsurface liquid ocean on the surface ice moons

NASA Astrophysics Data System (ADS)

Ozorovich, Yuri; Linkin, Vacheslav; Kosov, Alexandr; Fournier-Sicre, Alain; Klimov, Stanislav; Novikov, Denis; Ivanov, Anton; Skulachev, Dmitriy; Menshenin, Yaroslav

2016-04-01

This paper presents a new conceptual and methodological approach for geophysical survey of the planetary geoelectrical markers and oreols of the subsurface liquid ocean on the surface ice moons on the base "conceptual design phase" of the future space missions on the ice moons. At the design stage of such projects is considered the use of various space instruments and tools for the full the complex geophysical studies of the manifestations and planetary processes of the subsurface liquid ocean on the surface ice moons. The existence of various forms of the cryolithozone on terrestrial planets and their moons: advanced Martian permafrost zone in the form of existing of the frozen polar caps, subsurface frozen horizons, geological markers and oreols of the martian ancient (relict) ocean, subsurface oceans of Jupiter's and Saturn's moons-Europe and Enceladus, with the advanced form of permafrost freezes planetary caps, it allows to develop a common methodological basis and operational geophysical instruments (tools) for the future space program and planning space missions on these unique objects of the solar system, specialized for specific scientific problems of planetary missions. Geophysical practices and methodological principles, used in 1985-2015 by aurthors [ 1-5 ], respectively, as an example of the comprehensive geophysical experiment MARSES to study of the Martian permafrost zone and the martian ancient (relict) ocean, creating the preconditions for complex experimental setting and geo-physical monitoring of operational satellites of Jupiter and Saturn- Europe and Enceladus. This range of different planetary (like) planets with its geological history and prehistory of the common planetology formation processes of the planets formation and to define the role of a liquid ocean under the ice as a climate indicator of such planets, which is extremely important for the future construction of the geological and climatic history of the Earth. Main publications: [1

Galileo's Medicean Moons (IAU S269)

NASA Astrophysics Data System (ADS)

Barbieri, Cesare; Chakrabarti, Supriya; Coradini, Marcello; Lazzarin, Monica

2010-11-01

Preface; 1. Galileo's telescopic observations: the marvel and meaning of discovery George V. Coyne, S. J.; 2. Popular perceptions of Galileo Dava Sobel; 3. The slow growth of humility Tobias Owen and Scott Bolton; 4. A new physics to support the Copernican system. Gleanings from Galileo's works Giulio Peruzzi; 5. The telescope in the making, the Galileo first telescopic observations Alberto Righini; 6. The appearance of the Medicean Moons in 17th century charts and books. How long did it take? Michael Mendillo; 7. Navigation, world mapping and astrometry with Galileo's moons Kaare Aksnes; 8. Modern exploration of Galileo's new worlds Torrence V. Johnson; 9. Medicean Moons sailing through plasma seas: challenges in establishing magnetic properties Margaret G. Kivelson, Xianzhe Jia and Krishan K. Khurana; 10. Aurora on Jupiter: a magnetic connection with the Sun and the Medicean Moons Supriya Chakrabarti and Marina Galand; 11. Io's escaping atmosphere: continuing the legacy of surprise Nicholas M. Schneider; 12. The Jovian Rings Wing-Huen Ip; 13. The Juno mission Scott J. Bolton and the Juno Science Team; 14. Seeking Europa's ocean Robert T. Pappalardo; 15. Europa lander mission: a challenge to find traces of alien life Lev Zelenyi, Oleg Korablev, Elena Vorobyova, Maxim Martynov, Efraim L. Akim and Alexander Zakahrov; 16. Atmospheric moons Galileo would have loved Sushil K. Atreya; 17. The study of Mercury Louise M. Prockter and Peter D. Bedini; 18. Jupiter and the other giants: a comparative study Thérèse Encrenaz; 19. Spectroscopic and spectrometric differentiation between abiotic and biogenic material on icy worlds Kevin P. Hand, Chris McKay and Carl Pilcher; 20. Other worlds, other civilizations? Guy Consolmagno, S. J.; 21. Concluding remarks Roger M. Bonnet; Posters; Author index; Object index.

The Jupiter System Observer: Probing the Foundations of Planetary Systems

NASA Astrophysics Data System (ADS)

Senske, D.; Prockter, L.; Collins, G.; Cooper, J.; Hendrix, A.; Hibbitts, K.; Kivelson, M.; Orton, G.; Schubert, G.; Showman, A.; Turtle, E.; Williams, D.; Kwok, J.; Spilker, T.; Tan-Wang, G.

2007-12-01

Galileo's observations in the 1600's of the dynamic system of Jupiter and its moons launched a revolution in understanding the way planetary systems operate. Now, some 400 years later, the discovery of extra solar planetary systems with Jupiter-sized bodies has led to a similar revolution in thought regarding how these systems form and evolve. From the time of Galileo, the Jovian system has been viewed as a solar system in miniature, providing a laboratory to study, diverse and dynamic processes in a single place. The icy Galilean satellites provide a window into solar system history by preserving in their cratering records a chronology dating back nearly 4.5 By and extending to the present. The continuously erupting volcanoes of Io may provide insight into the era when magma oceans were common. The discovery of an internally generated magnetic field at Ganymede, one of only three terrestrial bodies to possess such a field, is a place to gain insight as to how dynamos work. The confirmation and characterization of icy satellite subsurface oceans impacts the way habitability is considered. Understanding the composition and volatile inventory of Jupiter can shed light into how planets accrete from the solar nebulae. Finally, like our sun, Jupiter influences its system through its extensive magnetic field. In early 2007, NASA's Science Mission Directorate formed four Science Definition Teams (SDTs) to formulate science goals and objectives in anticipation of the initiation of a flagship-class mission to the outer solar system (Europa, Jupiter system, Titan and Enceladus). The Jupiter System Observer (JSO) mission concept emphasizes overall Jupiter system science: 1) Jupiter and its atmosphere, 2) the geology and geophysics of the Galilean satellites (Io, Europa, Ganymede and Callisto), 3) the magnetosphere environment - both Jupiter's and Ganymede's&pand 4) interactions within the system. Focusing on the unique geology, presence of an internal magnetic field and

The Europa Jupiter system mission

NASA Astrophysics Data System (ADS)

Clark, K.; Stankov, A.; Pappalardo, R. T.; Greeley, R.; Blanc, M.; Lebreton, J.-P.; van Houten, T.

2009-04-01

Europa Jupiter System Mission (EJSM)— would be an international mission that would achieve Decadal Survey and Cosmic Vision goals. NASA and ESA have concluded a joint study of a mission to Europa, Ganymede and the Jupiter system with orbiters developed by NASA and ESA; contributions by JAXA are also possible. The baseline EJSM architecture consists of two primary elements operating in the Jovian system: the NASA-led Jupiter Europa Orbiter (JEO), and the ESA-led Jupiter Ganymede Orbiter (JGO). JEO and JGO would execute an intricately choreographed exploration of the Jupiter System be-fore settling into orbit around Europa and Ganymede, respectively. JEO and JGO would carry eleven and ten complementary instruments, respectively, to monitor dynamic phenomena (such as Io's volcanoes and Jupi-ter's atmosphere), map the Jovian magnetosphere and its interactions with the Galilean satellites, and charac-terize water oceans beneath the ice shells of Europa and Ganymede. EJSM would fully addresses high priority science objectives identified by the National Research Coun-cil's (NRC's) Decadal Survey and ESA's Cosmic Vi-sion for exploration of the outer solar system. The De-cadal Survey recommended a Europa Orbiter as the highest priority outer planet flagship mission and also identified Ganymede as a highly desirable mission tar-get. EJSM would uniquely addresse several of the cen-tral themes of ESA's Cosmic Vision Programme, through its in-depth exploration of the Jupiter system and its evolution from origin to habitability. EJSM would investigate the potential habitability of the active ocean-bearing moons Europa and Gany-mede, detailing the geophysical, compositional, geo-logical, and external processes that affect these icy worlds. EJSM would also explore Io and Callisto, Jupi-ter's atmosphere, and the Jovian magnetosphere. By understanding the Jupiter system and unraveling its history, the formation and evolution of gas giant plan-ets and their satellites would be

Derivation of the collision probability between orbiting objects The lifetimes of Jupiter's outer moons

NASA Technical Reports Server (NTRS)

Kessler, D. J.

1981-01-01

A general form is derived for Opik's equations relating to the probability of collision between two orbiting objects to their orbital elements, and used to determine the collisional lifetime of the eight outer moons of Jupiter. The derivation is based on a concept of spatial density, or average number of objects found in a unit volume, and results in a set of equations that are easily applied to a variety of orbital collision problems. When applied to the outer satellites, which are all in irregular orbits, the equations predict a relatively long collisional lifetime for the four retrograde moons (about 270 billon years on the average) and a shorter time for the four posigrade moons (0.9 billion years). This short time is suggestive of a past collision history, and may account for the orbiting dust detected by Pioneers 10 and 11.

Icy Profile

NASA Image and Video Library

2008-10-20

The Cassini spacecraft looks toward Rhea cratered, icy landscape with the dark line of Saturn ringplane and the planet murky atmosphere as a background. Rhea is Saturn second-largest moon, at 1,528 kilometers 949 miles across.

Origin of Saturn's rings and inner moons by mass removal from a lost Titan-sized satellite.

PubMed

Canup, Robin M

2010-12-16

The origin of Saturn's rings has not been adequately explained. The current rings are more than 90 to 95 per cent water ice, which implies that initially they were almost pure ice because they are continually polluted by rocky meteoroids. In contrast, a half-rock, half-ice mixture (similar to the composition of many of the satellites in the outer Solar System) would generally be expected. Previous ring origin theories invoke the collisional disruption of a small moon, or the tidal disruption of a comet during a close passage by Saturn. These models are improbable and/or struggle to account for basic properties of the rings, including their icy composition. Saturn has only one large satellite, Titan, whereas Jupiter has four large satellites; additional large satellites probably existed originally but were lost as they spiralled into Saturn. Here I report numerical simulations of the tidal removal of mass from a differentiated, Titan-sized satellite as it migrates inward towards Saturn. Planetary tidal forces preferentially strip material from the satellite's outer icy layers, while its rocky core remains intact and is lost to collision with the planet. The result is a pure ice ring much more massive than Saturn's current rings. As the ring evolves, its mass decreases and icy moons are spawned from its outer edge with estimated masses consistent with Saturn's ice-rich moons interior to and including Tethys.

From Galileo's telescope to the Galileo spacecraft: our changing views of the Jupiter system

NASA Astrophysics Data System (ADS)

Lopes, R. M.

2008-12-01

In four centuries, we have gone from the discovery of the four large moons of Jupiter - Io, Europa, Ganymede, and Callisto - to important discoveries about these four very different worlds. Galileo's telescopic discovery was a major turning point in the understanding of science. His observations of the moons' motion around Jupiter challenged the notion of an Earth-centric Universe. A few months later, Galileo discovered the phases of Venus, which had been predicted by the heliocentric model of the Solar System. Galileo also observed the rings of Saturn (which he mistook for planets) and sunspots, and was the first person to report mountains and craters on the Moon, whose existence he deduced from the patterns of light and shadow on the Moon's surface, concluding that the surface was topographically rough. Centuries later, the Galileo spacecraft's discoveries challenged our understanding of outer planet satellites. Results included the discovery of an icy ocean underneath Europa's surface, the possibility of life on Europa, the widespread volcanism on Io, and the detection of a magnetic field around Ganymede. All four of these satellites revealed how the major geologic processes - volcanism, tectonism, impact cratering and erosion - operate in these different bodies, from the total lack of impact craters on Io to the heavily cratered, ancient surface of Callisto. The Galileo spacecraft's journey also took it to Venus and the Moon, making important scientific observations about these bodies. The spacecraft discovered the first moon orbiting around an asteroid which, had Galileo the man observed, would have been another major blow for the geocentric model of our Solar System.

UV Reflectance of Jupiter's Moon Europa and Asteroid (16) Psyche

NASA Astrophysics Data System (ADS)

Becker, T. M.; Retherford, K. D.; Roth, L.; Hendrix, A.; McGrath, M. A.; Cunningham, N.; Feaga, L. M.; Saur, J.; Elkins-Tanton, L. T.; Walhund, J. E.; Molyneux, P.

2017-12-01

Surface reflectance observations of solar system objects in the UV are not only complimentary to longer wavelength observations for identifying surface composition, but can also reveal new and meaningful information about the surfaces of those bodies. On Europa, far-UV (FUV) spectral observations made by the Hubble Space Telescope (HST) show that the surface lacks a strong water ice absorption edge near 165 nm, which is intriguing because such a band has been detected on most icy satellites. This may suggest that radiolytic processing by Jupiter's magnetosphere has altered the surface, causing absorption at wavelengths longward of the H2O edge, masking this feature. Additionally, the FUV spectra are blue (increasing albedo with shorter wavelengths), and regions that are observed to be dark in the visible appear bright in the FUV. This spectral inversion, also observed on the Moon and some asteroids, may provide insight into the properties of the surface material and how they are processed.We also explore the UV reflectance spectra of the main belt asteroid (16) Psyche. This asteroid is believed to be the metallic remnant core of a differentiated asteroid, stripped of its mantle through collisions. However, there is speculation that the asteroid could have formed as-is from highly reduced metal-rich material near the Sun early in the formation of the solar system. Further, spectral observations in the infrared have revealed pyroxene and hydroxyl on the asteroid's surface, complicating the interpretation that (16) Psyche is a pure metallic object. Laboratory studies indicate that there are diagnostic spectral features in the UV that could be useful for determining the surface composition. We obtained HST observations of Psyche from 160 - 300 nm. Preliminary results show a featureless, red-sloped spectrum, inconsistent with significant amounts of pyroxene on the surface. We will present the spectra of Europa and the asteroid (16) Psyche and discuss the unique details

Iceless Icy Moons: Is the Nice Model In Trouble?

NASA Astrophysics Data System (ADS)

Dones, Henry C. Luke; Levison, H. F.

2012-05-01

Nimmo and Korycansky (2012; henceforth NK12) stated that if the outer Solar System underwent a Late Heavy Bombardment (LHB) in the Nice model, the mass striking the icy satellites at speeds up to tens of km/s would have vaporized so much ice that moons such as Mimas, Enceladus, and Miranda would have been devolatilized. NK12's possible explanations of this apparent discrepancy with observations include (1) the mass influx was a factor of 10 less than that in the Nice model; (2) the mass distribution of the impactors was top-heavy, so that luck might have saved some of the moons from suffering large, vapor-removing impacts; or (3) the inner moons formed after the LHB. NK12 calculated the mass influx onto the satellites from the lunar impact rate estimated by Gomes et al. (2005) and scaling factors calculated by Zahnle et al. (1998, 2003; also see Barr and Canup 2010). Production of vapor in hypervelocity impacts is calculated from Kraus et al. (2011). Our preliminary results show that there is about an order-of-magnitude uncertainty in the mass striking the satellites during the LHB, with NK12's estimate at the upper end of the range. We will discuss how the mass influx depends on the velocity and mass distributions of the impactors. The Nice model lives. We thank the NASA Lunar Science Institute (http://lunarscience.nasa.gov/) for support. Barr, A.C., Canup, R.M., Nature Geoscience 3, 164-167 (2010). Gomes, R., Levison, H.F., Tsiganis, K., Morbidelli, A., Nature 435, 466-469 (2005). Kraus, R.G., Senft, L.E., Stewart, S.T., Icarus 214, 724-738 (2011). Nimmo, F., Korycansky, D.G., Icarus, in press, http://www.sciencedirect.com/science/article/pii/S0019103512000310 (2012). Zahnle, K., Dones, L., Levison, H.F., Icarus 136, 202-222 (1998). Zahnle, K., Schenk, P., Levison, H.F., Dones, L., Icarus 163, 263-289 (2003).

The first laboratory measurements of sulfur ions sputtering water ice

NASA Astrophysics Data System (ADS)

Galli, André; Pommerol, Antoine; Vorburger, Audrey; Wurz, Peter; Tulej, Marek; Scheer, Jürgen; Thomas, Nicolas; Wieser, Martin; Barabash, Stas

2015-04-01

The upcoming JUpiter ICy moons Explorer mission to Europa, Ganymede, and Callisto has renewed the interest in the interaction of plasma with an icy surface. In particular, the surface release processes on which exosphere models of icy moons rely should be tested with realistic laboratory experiments. We therefore use an existing laboratory facility for space hardware calibration in vacuum to measure the sputtering of water ice due to hydrogen, oxygen, and sulfur ions at energies from 1 keV to 100 keV. Pressure and temperature are comparable to surface conditions encountered on Jupiter's icy moons. The sputter target is a 1cm deep layer of porous, salty water ice. Our results confirm theoretical predictions that the sputter yield from oxygen and sulfur ions should be similar. Thanks to the modular set-up of our experiment we can add further surface processes relevant for icy moons, such as electron sputtering, sublimation, and photodesorption due to UV light.

A Secondary Ion Mass Analyzer for Remote Surface Composition Analysis of the Galilean Moons

NASA Technical Reports Server (NTRS)

Krueger, H.; Srama, R.; Johnson, T. V.; Henkel, H.; vonHoerner, H.; Koch, A.; Horanyi, M.; Gruen, E.; Kissel, J.; Krueger, F.

2003-01-01

Galileo in-situ dust measurements have shown that the Galilean moons are surrounded by tenuous dust clouds formed by collisional ejecta from their icy surfaces, kicked up by impacts of interplanetary micrometeoroids. The majority of the ejecta dust particles have been sensed at altitudes below five between 0.5 and 1 micron, just above the detector threshold, indicating a size distribution decreasing towards bigger particles. their parent bodies. They carry information about the properties of the surface from which they have been kicked up. In particular, these grains may carry organic compounds and other chemicals of biological relevance if they exist on the icy Galilean moons. In-situ analysis of the grain composition with a sophisticated dust analyzer instrument flying on a Jupiter Icy Moons Orbiter can provide important information about geochemical and geophysical processes during the evolutionary histories of these moons which are not accessible with other techniques from an orbiter spacecraft. Thus, spacecraft-based in-situ dust measurements can be used as a diagnostic tool for the analysis of the surface composition of the moons. This way, the in-situ measurements turn into a remote sensing technique by using the dust instrument like a telescope for surface investigation. An instrument capable of very high resolution composition analysis of dust particles is the Cometary Secondary Ion Mass Analyzer (COSIMA). The instrument was originally developed for the Comet Rendezvous and Asteroid Flyby (CRAF) mission and has now been built for ESA'S comet orbiter Rosetta. Dust particles are collected on a target and are later located by an optical microscope camera. A pulsed primary indium ion gun partially ionizes the dust grains. The generated secondary ions are accelerated in an electric field and travel through a reflectron-type time-of-flight ion mass spectrometer.

Thickness Constraints on the Icy Shells of the Galilean Satellites from a Comparison of Crater Shapes

NASA Technical Reports Server (NTRS)

Schenk, Paul M.

2002-01-01

A thin outer ice shell on Jupiter's large moon Europa would imply easy exchange between the surface and any organic or biotic material in its putative subsurface ocean. The thickness of the outer ice shell is poorly constrained, however, with model-dependent estimates ranging from a few kilometers of depths of impact craters on Europa, Ganymede and Callisto that reveal two anomalous transitions in crater shape with diameter. The first transition is probably related to temperature-dependent ductility of the crust at shallow depths (7-8 km on Europa). The second transition is attributed to the influence of subsurface oceans on all three satellites, which constrains Europa's icy shell to be at least 19 km thick. The icy lithospheres of Ganymede and Callisto are equally ice-rich, but Europa's icy shell has a thermal structure about 0.25-0.5 times the thickness of Ganymede's or Callisto's shells, depending on epoch. The appearances of the craters on Europa are inconsistent with thin-ice-shell models and indicate that exchange of oceanic and surface material could be difficult.

X-ray Probes of Magnetospheric Interactions with Jupiter's Auroral zones, the Galilean Satellites, and the Io Plasma Torus

NASA Technical Reports Server (NTRS)

Elsner, R. F.; Ramsey, B. D.; Waite, J. H., Jr.; Rehak, P.; Johnson, R. E.; Cooper, J. F.; Swartz, D. A.

2004-01-01

Remote observations with the Chandra X-ray Observatory and the XMM-Newton Observatory have shown that the Jovian system is a source of x-rays with a rich and complicated structure. The planet's polar auroral zones and its disk are powerful sources of x-ray emission. Chandra observations revealed x-ray emission from the Io Plasma Torus and from the Galilean moons Io, Europa, and possibly Ganymede. The emission from these moons is certainly due to bombardment of their surfaces of highly energetic protons, oxygen and sulfur ions from the region near the Torus exciting atoms in their surfaces and leading to fluorescent x-ray emission lines. Although the x-ray emission from the Galilean moons is faint when observed fiom Earth orbit, an imaging x-ray spectrometer in orbit around these moons, operating at 200 eV and above with 150 eV energy resolution, would provide a detailed mapping (down to 40 m spatial resolution) of the elemental composition in their surfaces. Here we describe the physical processes leading to x-ray emission fiom the surfaces of Jupiter's moons and the instrumental properties, as well as energetic ion flux models or measurements, required to map the elemental composition of their surfaces. We discuss the proposed scenarios leading to possible surface compositions. For Europa, the two most extreme are (1) a patina produced by exogenic processes such as meteoroid bombardment and ion implantation, and (2) upwelling of material fiom the subsurface ocean. We also describe the characteristics of X - m , an imaging x-ray spectrometer under going a feasibility study for the JIM0 mission, with the ultimate goal of providing unprecedented x-ray studies of the elemental composition of the surfaces of Jupiter's icy moons and Io, as well as of Jupiter's auroral x-ray emission.

Photographer : JPL Range : 4.2 million km. ( 2.6 million miles ) Jupiter's moon Europa, the size of

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 4.2 million km. ( 2.6 million miles ) Jupiter's moon Europa, the size of earth's moon, is apparently covered by water ice, as indicated by ground spectrometers and its brightness. In this view, global scale dark sreaks discovered by Voyager 1 that criss-cross the the satelite are becoming visible. Bright rayed impact craters, which are abundant on Ganymede and Callisto, would be easily visible at this range, suggesting that Europa's surface is young and that the streaks are reflections of currently active internal dynamic processes.

IR reflectance spectroscopy of carbon dioxide clathrate hydrates. Implications for Saturn's icy moons.

NASA Astrophysics Data System (ADS)

Oancea, A.; Grasset, O.; Le Menn, E.; Bezacier, L.; Bollengier, O.; Le Mouélic, S.; Tobie, G.

2012-04-01

A CO2 spectral band was discovered by VIMS on the Saturn's satellites Dione, Hyperion, Iapetus and Phoebe [1]. The band position on the three first satellites corresponds to CO2 trapped in a complex material, but no indication exists whether this latter is water ice or some mineral or complex organic compound [1]. On Phoebe, the CO2 spectral band is consistent with solid CO2 or CO2 molecules trapped in the small cages of a clathrate hydrate structure [2]. It is thought that clathrate hydrates could play a significant role in the chemistry of the solar nebula [3] and in the physical evolution of astrophysical objects [4]. But so far, no clathrate hydrate structure has been observed in astrophysical environments. Moreover, identification of molecules trapped in a clathrate hydrate structure is extremely difficult because of the strong IR vibration modes of the water ice matrix. In this work, experimental IR reflectance spectra for CO2 clathrate hydrates are studied on grains and films. Clathrates are synthesized in a high pressure autoclave at low temperatures. IR spectral analysis is made with a low pressure and low temperature cryostat. These experimental conditions - 80 < T < 110 K, P~10-5 bar - are relevant to icy moons' surfaces. We have observed that the IR reflectance, in the spectral region (3 - 5 μm) characterized by H2O and CO2 high absorption coefficients, is strongly dependent on physical (size, surface) and optical (n and k) properties of the samples. The impact of these parameters on the CO2 clathrate IR reflectance spectrum will be presented. A comparison between the absorption bands of CO2 clathrate hydrates obtained in our lab and CO2 absorption bands as detected by VIMS on the icy satellites of Saturn will be shown. This experimental work confirms that VIMS data are not consistent with the presence of structure I CO2 clathrate hydrates on the surface of the icy moons. Possibility of having metastable structure II still remains unsolved and will be

Coupling of the Matched Gravity and Electromagnetic Fields of the Sun with Jupiter and its Moons Together in Nearest Portion of Jupiter's Orbit to the Sun as the Main Cause of the Peak of Approximately 11 Yearly Solar Cycles and Hazards from Solar Storms

NASA Astrophysics Data System (ADS)

Gholibeigian, Kazem; Gholibeigian, Hassan

2016-04-01

On March 13, 1989 the entire province of Quebec Blackout by solar storm during solar cycle 22. The solar storm of 1859, also known as the Carrington event, was a powerful geomagnetic solar storm during solar cycle 10. The solar storm of 2012 during solar cycle 24 was of similar magnitude, but it passed Earth's orbit without striking the plane. All of these solar storms occurred in the peak of 11 yearly solar cycles. In this way, the White House in its project which is focusing on hazards from solar system, in a new strategy and action plan to increase protection from damaging solar emissions, should focus on coupling of the matched Gravity and Electromagnetic Fields)GEFs) of the Sun with Jupiter and its moons together. On the other hand, in solar system, the Jupiter's gravity has largest effect to the Sun's core and its dislocation, because the gravity force between the Jupiter and the Sun is 11.834 times, In addition overlapping of the solar cycles with the Jupiter's orbit period is 11.856 years. These observable factors lead us to the effect of the Jupiter and Sun gravity fields coupling as the main cause of the approximately 11 years duration for solar cycles. Its peak in each cycle is when the Jupiter is in nearest portion to the Sun in its orbit. In this way, the other planets in their coupling with Sun help to the variations and strengthening solar cycles. [Gholibeigian, 7/24/2015http://adsabs.harvard.edu/abs/2014EGU]. In other words, the both matched GEFs are generating by the large scale forced convection system inside the stars and planets [Gholibeigian et. al, AGU Fall Meeting 2015]. These two fields are couple and strengthening each other. The Jupiter with its 67 moons generate the largest coupled and matched GEFs in its core and consequently strongest effect on the Sun's core. Generation and coupling of the Jupiter's GEFs with its moons like Europa, Io and Ganymede make this planet of thousands of times brighter and many times bigger than Earth as the

Thickness constraints on the icy shells of the galilean satellites from a comparison of crater shapes.

PubMed

Schenk, Paul M

2002-05-23

A thin outer ice shell on Jupiter's large moon Europa would imply easy exchange between the surface and any organic or biotic material in its putative subsurface ocean. The thickness of the outer ice shell is poorly constrained, however, with model-dependent estimates ranging from a few kilometres to ten or more kilometres. Here I present measurements of depths of impact craters on Europa, Ganymede and Callisto that reveal two anomalous transitions in crater shape with diameter. The first transition is probably related to temperature-dependent ductility of the crust at shallow depths (7 8 km on Europa). The second transition is attributed to the influence of subsurface oceans on all three satellites, which constrains Europa's icy shell to be at least 19 km thick. The icy lithospheres of Ganymede and Callisto are equally ice-rich, but Europa's icy shell has a thermal structure about 0.25 0.5 times the thicknesses of Ganymede's or Callisto's shells, depending on epoch. The appearances of the craters on Europa are inconsistent with thin-ice-shell models and indicate that exchange of oceanic and surface material could be difficult.

Plume Collection Strategies for Icy World Sample Return

NASA Technical Reports Server (NTRS)

Neveu, M.; Glavin, D. P.; Tsou, P.; Anbar, A. D.; Williams, P.

2015-01-01

Three icy worlds in the solar system display evidence of pluming activity. Water vapor and ice particles emanate from cracks near the south pole of Saturn's moon Enceladus. The plume gas contains simple hydrocarbons that could be fragments of larger, more complex organics. More recently, observations using the Hubble and Herschel space telescopes have hinted at transient water vapor plumes at Jupiter's moon Europa and the dwarf planet Ceres. Plume materials may be ejected directly from possible sub-surface oceans, at least on Enceladus. In such oceans, liquid water, organics, and energy may co-exist, making these environments habitable. The venting of habitable ocean material into space provides a unique opportunity to capture this material during a relatively simple flyby mission and return it to Earth. Plume collection strategies should enable investigations of evidence for life in the returned samples via laboratory analyses of the structure, distribution, isotopic composition, and chirality of the chemical components (including biomolecules) of plume materials. Here, we discuss approaches for the collection of dust and volatiles during flybys through Enceladus' plume, based on Cassini results and lessons learned from the Stardust comet sample return mission. We also highlight areas where sample collector and containment technology development and testing may be needed for future plume sample return missions.

Saturn and 4 Icy Moons in Natural Color

NASA Image and Video Library

1998-06-08

This approximate natural-color image shows Saturn, its rings, and four of its icy satellites. Three satellites (Tethys, Dione, and Rhea) are visible against the darkness of space, and another smaller satellite (Mimas) is visible against Saturn's cloud tops very near the left horizon and just below the rings. The dark shadows of Mimas and Tethys are also visible on Saturn's cloud tops, and the shadow of Saturn is seen across part of the rings. Saturn, second in size only to Jupiter in our Solar System, is 120,660 km (75,000 mi) in diameter at its equator (the ring plane) but, because of its rapid spin, Saturn is 10% smaller measured through its poles. Saturn's rings are composed mostly of ice particles ranging from microscopic dust to boulders in size. These particles orbit Saturn in a vast disk that is a mere 100 meters (330 feet) or so thick. The rings' thinness contrasts with their huge diameter--for instance 272,400 km (169,000 mi) for the outer part of the bright A ring, the outermost ring visible here. The pronounced concentric gap in the rings, the Cassini Division (named after its discoverer), is a 3500-km wide region (2200 mi, almost the width of the United States) that is much less populated with ring particles than the brighter B and A rings to either side of the gap. The rings also show some enigmatic radial structure ('spokes'), particularly at left. This image was synthesized from images taken in Voyager's blue and violet filters and was processed to recreate an approximately natural color and contrast. http://photojournal.jpl.nasa.gov/catalog/PIA00400

Habitability potential of satellites around Jupiter and Saturn

NASA Astrophysics Data System (ADS)

Coustenis, Athena; Raulin, Francois; Encrenaz, Therese; Grasset, Olivier; Solomonidou, Anezina

2016-07-01

biomarkers. Currently, for Titan and Enceladus, geophysical models try to explain the possible existence of an oceanic layer that decouples the mantle from the icy crust. Titan has further been suggested to be a possible cryovolcanic world due to the presence of local complex volcanic-like geomorphology and the indications of surface albedo changes with time [7,8]. Such dynamic activity that would most probably include tidal heating, possible internal convection, and ice tectonics, is believed to be a pre-requisite of a habitable planetary body as it allows the recycling of minerals and potential nutrients and provides localized energy sources. In one of our geophysical studies [4], we have showed that tidal forces are a constant and significant source of internal deformation on Titan and the interior liquid water ocean can be relatively warm for reasonable amounts of ammonia concentrations, thus completing the set of parameters needed for a truly habitable planetary body. If the silicate mantles of Europa and Ganymede and the liquid sources of Titan and Enceladus are geologically active as on Earth, giving rise to the equivalent of hydrothermal systems, the simultaneous presence of water, geodynamic interactions, chemical energy sources and a diversity of key chemical elements may fulfill the basic conditions for habitability. Such habitability indications from bodies at distances of 10 AU, are essential discoveries brought to us by space exploration and which have recently revolutionized our perception of habitability in the solar system. In the solar system's neighborhood, such potential habitats can only be investigated with appropriate designed space missions, like JUICE (JUpiter ICy moon Explorer) for Ganymede and Europa [9]. JUICE is an ESA mission to Jupiter and its icy moons, recently selected to launch in 2022. Other future mission concepts are being studied for exploring the moons around Saturn. References: [1] Coustenis, A., Encrenaz, Th., in "Life Beyond Earth

Physical Conditions and Exobiology Potential of Icy Satellites of the Giant Planets

NASA Astrophysics Data System (ADS)

Simakov, M. B.

2017-05-01

All giant planets of the Solar system have a big number of satellites. A small part of them consist very large bodies, quite comparable to planets of terrestrial type, but including very significant share of water ice. Galileo spacecraft has given indications, primarily from magnetometer and gravity data, of the possibility that three of Jupiter's four large moons, Europa, Ganymede and Callisto have internal oceans. Formation of such satellites is a natural phenomenon, and satellite systems definitely should exist at extrasolar planets. The most recent models of the icy satellites interior lead to the conclusion that a substantial liquid layer exists today under relatively thin ice cover inside. The putative internal water ocean provide some exobiological niches on these bodies. We can see all conditions needed for origin and evolution of biosphere - liquid water, complex organic chemistry and energy sources for support of biological processes - are on the moons. The existing of liquid water ocean within icy world can be consequences of the physical properties of water ice, and they neither require the addition of antifreeze substances nor any other special conditions. On Earth life exists in all niches where water exists in liquid form for at least a portion of the year. Possible metabolic processes, such as nitrate/nitrite reduction, sulfate reduction and methanogenesis could be suggested for internal oceans of Titan and Jovanian satellites. Excreted products of the primary chemoautotrophic organisms could serve as a source for other types of microorganisms (heterotrophes). Subglacial life may be widespread among such planetary bodies as satellites of extrasolar giant planets, detected in our Galaxy.

Hubble Captures Rare Triple-Moon Conjunction

NASA Image and Video Library

2015-02-06

Three moons and their shadows parade across Jupiter near the end of the event at 07:10 UT on January 24, 2015. Europa has entered the frame at lower left. Slower-moving Callisto is above and to the right of Europa. Fastest-moving Io is approaching the eastern limb of the planet. Europa's shadow is toward the left side of the image and Callisto's shadow to the right. (The moons' orbital velocities are proportionally slower with increasing distance from the planet.) Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) More info: Firing off a string of snapshots like a sports photographer at a NASCAR race, NASA's Hubble Space Telescope captured a rare look at three of Jupiter's largest moons zipping across the banded face of the gas-giant planet: Europa, Callisto, and Io. Jupiter's four largest moons can commonly be seen transiting the face of the giant planet and casting shadows onto its cloud tops. However, seeing three moons transiting the face of Jupiter at the same time is rare, occurring only once or twice a decade. Missing from the sequence, taken on January 24, 2015, is the moon Ganymede that was too far from Jupiter in angular separation to be part of the conjunction. 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

Jovian Moon Shadow

NASA Image and Video Library

2017-10-19

Jupiter's moon Amalthea casts a shadow on the gas giant planet in this image captured by NASA's Juno spacecraft. The elongated shape of the shadow is a result of both the location of the moon with relation to Jupiter in this image as well as the irregular shape of the moon itself. The image was taken on Sept. 1, 2017 at 2:46 p.m. PDT (5:46 p.m. EDT), as Juno performed its eighth close flyby of Jupiter. At the time the image was taken, the spacecraft was 2,397 miles (3,858 kilometers) from the tops of the clouds of the planet at a latitude of 17.6 degrees. Citizen scientists Gerald Eichstädt and Seán Doran processed this image using data from the JunoCam imager. The image has been rotated so that the top of the image is actually the equatorial regions while the bottom of the image is of the northern polar regions of the planet. https://photojournal.jpl.nasa.gov/catalog/PIA21969

Geologic Evolution of Saturn's Icy Moon Tethys

NASA Astrophysics Data System (ADS)

Wagner, Roland; Stephan, K.; Schmedemann, N.; Roatsch, T.; Kersten, E.; Neukum, G.; Porco, C. C.

2013-10-01

Tethys, 1072 km in diameter, is a mid-sized icy moon of Saturn imaged for the first time in two Voyager flybys [1][2][3]. Since July 2004, its surface has been imaged by the Cassini ISS cameras at resolutions between 200 and 500 m/pxl. We present results from our ongoing work to define and map geologic units in camera images obtained preferentially during Cassini’s Equinox and Solstice mission phases. In the majority of Tethys’ surface area a densely cratered plains unit [1][2][3][this work] is abundant. The prominent graben system of Ithaca Chasma is mapped as fractured cratered plains. Impact crater and basin materials can be subdivided into three degradational classes. Odysseus is a fresh large impact basin younger than Ithaca Chasma according to crater counts [4]. Heavily degraded craters and basins occur in the densely cratered plains unit. A smooth, less densely cratered plains unit in the trailing hemisphere was previously identified by [2] but mapping of its boundaries is difficult due to varying viewing geometries of ISS images. To the south of Odysseus, we identified a cratered plains unit not seen in Voyager data, characterized by remnants of highly degraded large craters superimposed by younger fresher craters with a lower crater density compared to the densely cratered plains unit. Its distinct linear northern contact with the densely cratered plains suggests a tectonic origin. Sets of minor fractures can be distinguished in the densely cratered plains, and locally, features of mass wasting can be observed. References: [1] Smith B. A. et al. (1981), Science 212, 163-191. [2] Smith B. A. et al. (1982), Science 215, 504-537. [3] Moore J. M. and Ahern J. L. (1983), JGR 88 (suppl.), A577-A584. [4] Giese B. et al. (2007), GRL 34, doi:10.1029/2007GL031467.

Scientists Revise Thinking on Comets, Planet Jupiter

ERIC Educational Resources Information Center

Chemical and Engineering News, 1974

1974-01-01

Discusses scientific information obtained from Pioneer 10's Jupiter flyby and the comet Kohoutek's first trip around the sun, including the high hydrogen emission of Jupiter's principal moon, Io. (CC)

Ultraviolet Photometric Parameters of the Icy Galilean Satellites

NASA Technical Reports Server (NTRS)

Hendrix, Amanda R.; Domingue, Deborah L.; King, Kimberly

2002-01-01

The Galilean satellites are each phase-locked with Jupiter, so that one hemisphere (the Jovian hemisphere centered on 0 deg longitude) is always facing Jupiter. The leading hemisphere is centered on 90 deg W longitude, while the central longitude of the trailing hemisphere is 270 deg W. Because Jupiter's magnetosphere corotates at a rate faster than the orbital speed of the moons, the satellites' trailing hemispheres are affected by magnetospheric particle bombardment. Some effects are implantation of magnetospheric ions, sputtering, erosion and grain size alteration. The leading hemispheres of these moons are more dominantly affected by micrometeorite bombardment, while the Jovian hemispheres may be affected by dust and/or neutral wind particles streaming out radially from Io and its torus.

Possible Moonwich of Ice and Oceans on Ganymede Artist Concept

NASA Image and Video Library

2014-05-01

This artist concept of Jupiter moon Ganymede, the largest moon in the solar system, illustrates the club sandwich model of its interior oceans. Scientists suspect Ganymede has a massive ocean under an icy crust.

New Active Remote-sensing Capabilities: Laser Ablation Spectrometer and Lidar Atmospheric Species Profile Measurements

NASA Technical Reports Server (NTRS)

DeYoung, R. J.; Bergstralh, J. T.

2005-01-01

Introduction: With the anticipated development of high-capacity fission power and electric propulsion for deep-space missions, it will become possible to propose experiments that demand higher power than current technologies (e.g. radioisotope power sources) provide. Jupiter Icy Moons Orbiter (JIMO), the first mission in the Project Prometheus program, will explore the icy moons of Jupiter with a suite of high-capability experiments that take advantage of the high power levels (and indirectly, the high data rates) that fission power affords. This abstract describes two high-capability active-remote-sensing experiments that will be logical candidates for subsequent Prometheus-class missions.

Sharpening Up Jupiter

NASA Astrophysics Data System (ADS)

2008-10-01

New image-correction technique delivers sharpest whole-planet ground-based picture ever A record two-hour observation of Jupiter using a superior technique to remove atmospheric blur has produced the sharpest whole-planet picture ever taken from the ground. The series of 265 snapshots obtained with the Multi-Conjugate Adaptive Optics Demonstrator (MAD) prototype instrument mounted on ESO's Very Large Telescope (VLT) reveal changes in Jupiter's smog-like haze, probably in response to a planet-wide upheaval more than a year ago. Sharpening Up Jupiter ESO PR Photo 33/08 Sharpening Up Jupiter Being able to correct wide field images for atmospheric distortions has been the dream of scientists and engineers for decades. The new images of Jupiter prove the value of the advanced technology used by MAD, which uses two or more guide stars instead of one as references to remove the blur caused by atmospheric turbulence over a field of view thirty times larger than existing techniques [1]. "This type of adaptive optics has a big advantage for looking at large objects, such as planets, star clusters or nebulae," says lead researcher Franck Marchis, from UC Berkeley and the SETI Institute in Mountain View, California, USA. "While regular adaptive optics provides excellent correction in a small field of view, MAD provides good correction over a larger area of sky. And in fact, were it not for MAD, we would not have been able to perform these amazing observations." MAD allowed the researchers to observe Jupiter for almost two hours on 16 and 17 August 2008, a record duration, according to the observing team. Conventional adaptive optics systems using a single Jupiter moon as reference cannot monitor Jupiter for so long because the moon moves too far from the planet. The Hubble Space Telescope cannot observe Jupiter continuously for more than about 50 minutes, because its view is regularly blocked by the Earth during Hubble's 96-minute orbit. Using MAD, ESO astronomer Paola Amico

Infrared Spectra of Hydrated Magnesium Salts and their Role in the Search for Possible Life Conditions on Jupiter Moons

NASA Technical Reports Server (NTRS)

Chaban, Galina; Huo, Winifred M.; Lee, Timothy J.; Kwak, Dochan (Technical Monitor)

2002-01-01

Recent observations from the Galileo satellite indicate that three of the Jupiter moons, Europa, Ganymede, and Callisto, may have subsurface oceans. Possible existence of such ocean and the nature of its composition are of great interest to astrobiologists. Data from Galileo's NIMS spectrometer indicate the possibility of hydrated salts on Europa's surface. To aid in the design of future missions, we investigated infrared spectra of MgSO4-nH20, n=1-3 using ab initio calculations. Geometry, energetics, dipole moments, vibrational frequencies and infrared intensities of pure and hydrated MgSO4 salts were determined. Significant differences are found between vibrational spectra of water molecules in complexes with MgSO4 and pure water. Some of the O-H stretching frequencies in the complexes are shifted to the red by up to 1,500 - 2,000 per cm. In addition, the SO2 stretching vibrations are found at lower frequency regions than the water vibrations. The calculated bands of water and SO2 fragments can serve as markers for the existence of the salt-water complexes on the surface of Jupiter's moon.

Photographer : JPL Europa , the smallest of the Galilean satellites, or Moons , of Jupiter , is seen

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Europa , the smallest of the Galilean satellites, or Moons , of Jupiter , is seen here as taken by Voyager 1. Range : 2 million km (1.2 million miles) is centered at about the 300 degree Meridian. The bright areas are probably ice deposits, while the dark may be rocky surface or areas of more patchy ice distribution. Most unusual features are systems of linear structures crossing the surface in various directions. Of these, some of which are over 1000 km. long , & 2 or 3 hundred km. wide, may be faults which have disrupted the surface.

Two-phase convection in the high-pressure ice layer of the large icy moons: geodynamical implications

NASA Astrophysics Data System (ADS)

Kalousova, K.; Sotin, C.; Tobie, G.; Choblet, G.; Grasset, O.

2015-12-01

The H2O layers of large icy satellites such as Ganymede, Callisto, or Titan probably include a liquid water ocean sandwiched between the deep high-pressure ice layer and the outer ice I shell [1]. It has been recently suggested that the high-pressure ice layer could be decoupled from the silicate core by a salty liquid water layer [2]. However, it is not clear whether accumulation of liquids at the bottom of the high-pressure layer is possible due to positive buoyancy of water with respect to high-pressure ice. Numerical simulation of this two-phase (i.e. ice and water) problem is challenging, which explains why very few studies have self-consistently handled the presence and transport of liquids within the solid ice [e.g. 3]. While using a simplified description of water production and transport, it was recently showed in [4] that (i) a significant fraction of the high-pressure layer reaches the melting point and (ii) the melt generation and its extraction to the overlying ocean significantly influence the global thermal evolution and interior structure of the large icy moons.Here, we treat the high-pressure ice layer as a compressible mixture of solid ice and liquid water [5]. Several aspects are investigated: (i) the effect of the water formation on the vigor of solid-state convection and its influence on the amount of heat that is transferred from the silicate mantle to the ocean; (ii) the fate of liquids within the upper thermal boundary layer - whether they freeze or reach the ocean; and (iii) the effect of salts and volatile compounds (potentially released from the rocky core) on the melting/freezing processes. Investigation of these aspects will allow us to address the thermo-chemical evolution of the internal ocean which is crucial to evaluate the astrobiological potential of large icy moons. This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. [1] Hussmann et al. (2007), Treatise of

Juno Closes in on Jupiter

NASA Image and Video Library

2016-07-04

This is the final view taken by the JunoCam instrument on NASA's Juno spacecraft before Juno's instruments were powered down in preparation for orbit insertion. Juno obtained this color view on June 29, 2016, at a distance of 3.3 million miles (5.3 million kilometers) from Jupiter. The spacecraft is approaching over Jupiter's north pole, providing an unprecedented perspective on the Jupiter system, including its four large moons. http://photojournal.jpl.nasa.gov/catalog/PIA20706

Seeding life on the moons of the outer planets via lithopanspermia.

PubMed

Worth, R J; Sigurdsson, Steinn; House, Christopher H

2013-12-01

Material from the surface of a planet can be ejected into space by a large impact and could carry primitive life-forms with it. We performed n-body simulations of such ejecta to determine where in the Solar System rock from Earth and Mars may end up. We found that, in addition to frequent transfer of material among the terrestrial planets, transfer of material from Earth and Mars to the moons of Jupiter and Saturn is also possible, but rare. We expect that such transfers were most likely to occur during the Late Heavy Bombardment or during the ensuing 1-2 billion years. At this time, the icy moons were warmer and likely had little or no ice shell to prevent meteorites from reaching their liquid interiors. We also note significant rates of re-impact in the first million years after ejection. This could re-seed life on a planet after partial or complete sterilization by a large impact, which would aid the survival of early life during the Late Heavy Bombardment.

Dielectric properties of analogs of icy planetary surfaces in the mm-submm domain: review, new results and implications for the submillimeter sounding of Jovian satellites subsurfaces.

NASA Astrophysics Data System (ADS)

Brouet, Y.; Jacob, K.; Murk, A.; Cerubini, R.; Pommerol, A.; Thomas, N.

2017-12-01

Passive microwave radiometers are instruments which can sense thermal radiation coming from the subsurface (millimeters to centimeters) of an observed area. The penetration depth depends on the dielectric properties of the material, as they constrain the radiative transfer occurring below the surface. In order to interpret the data in terms of physical properties, the dielectric properties of material analogs as a function of several parameters (i.e., frequency, temperature, composition, porosity) have to be taken into account. Interpretations of radiometers data are limited by the few laboratory measurements developed in the millimeter domain, regarding measurements performed with rocky materials, planetary regolith simulants or volcanic ashes (Campbell and Ulrichs, 1969; Bertrand, 2004; Brouet et al., 2015). Furthermore, in preparation to the exploration of the Jupiter's icy moons with the JUICE mission and the Europa mission, Pettinelli et al. (2015) pointed out the lack of laboratory measurements in the microwave domain relevant for icy planetary subsurface observations. Firstly, we will review the existing data obtained with laboratory experiments operating in the millimeter-submillimeter domain relevant for radiometers aiming to determine subsurface properties of Solar System objects. Secondly, we will present an experimental set-up dedicated to the measurements of the dielectric properties of icy and dry samples in the millimeter-submillimeter domain, the sample preparation procedures and the first results. The measurements are based on a free-space reflection method and can be performed with sample temperatures below 200 K, as well as under dry air environment. First measurements have been performed in the 150 - 210 GHz range on a pure water ice sample and a pure hydrated sulfate (epsomite) sample, as well as on water ice/epsomite mixtures, which represent unique data in the mm-smm domain. Finally, we will discuss about the implications for the

High Resolution Globe of Jupiter

NASA Image and Video Library

2001-01-30

This true-color simulated view of Jupiter is composed of 4 images taken by NASA's Cassini spacecraft on December 7, 2000. To illustrate what Jupiter would have looked like if the cameras had a field-of-view large enough to capture the entire planet, the cylindrical map was projected onto a globe. The resolution is about 144 kilometers (89 miles) per pixel. Jupiter's moon Europa is casting the shadow on the planet. https://photojournal.jpl.nasa.gov/catalog/PIA02873

Abrupt Climate Transition of Icy Worlds from Snowball to Moist or Runaway Greenhouse

NASA Astrophysics Data System (ADS)

Yang, J.; Ding, F.; Ramirez, R. M.; Peltier, W. R.; Hu, Y.; Liu, Y.

2017-12-01

Ongoing and future space missions aim to identify potentially habitable planets in our Solar System and beyond. Planetary habitability is determined not only by a planet's current stellar insolation and atmospheric properties, but also by the evolutionary history of its climate. It has been suggested that icy planets and moons become habitable after their initial ice shield melts as their host stars brighten. Here we show from global climate model simulations that a habitable state is not achieved in the climatic evolution of those icy planets and moons that possess an inactive carbonate-silicate cycle and low concentrations of greenhouse gases. Examples for such planetary bodies are the icy moons Europa and Enceladus, and certain icy exoplanets orbiting G and F stars. We find that the stellar fluxes that are required to overcome a planet's initial snowball state are so large that they lead to significant water loss and preclude a habitable planet. Specifically, they exceed the moist greenhouse limit, at which water vapour accumulates at high altitudes where it can readily escape, or the runaway greenhouse limit, at which the strength of the greenhouse increases until the oceans boil away. We suggest that some icy planetary bodies may transition directly to a moist or runaway greenhouse without passing through a habitable Earth-like state.

Abrupt climate transition of icy worlds from snowball to moist or runaway greenhouse

NASA Astrophysics Data System (ADS)

Yang, Jun; Ding, Feng; Ramirez, Ramses M.; Peltier, W. R.; Hu, Yongyun; Liu, Yonggang

2017-08-01

Ongoing and future space missions aim to identify potentially habitable planets in our Solar System and beyond. Planetary habitability is determined not only by a planet's current stellar insolation and atmospheric properties, but also by the evolutionary history of its climate. It has been suggested that icy planets and moons become habitable after their initial ice shield melts as their host stars brighten. Here we show from global climate model simulations that a habitable state is not achieved in the climatic evolution of those icy planets and moons that possess an inactive carbonate-silicate cycle and low concentrations of greenhouse gases. Examples for such planetary bodies are the icy moons Europa and Enceladus, and certain icy exoplanets orbiting G and F stars. We find that the stellar fluxes that are required to overcome a planet's initial snowball state are so large that they lead to significant water loss and preclude a habitable planet. Specifically, they exceed the moist greenhouse limit, at which water vapour accumulates at high altitudes where it can readily escape, or the runaway greenhouse limit, at which the strength of the greenhouse increases until the oceans boil away. We suggest that some icy planetary bodies may transition directly to a moist or runaway greenhouse without passing through a habitable Earth-like state.

Thermal evolution of trans-Neptunian objects, icy satellites, and minor icy planets in the early solar system

NASA Astrophysics Data System (ADS)

Bhatia, Gurpreet Kaur; Sahijpal, Sandeep

2017-12-01

Numerical simulations are performed to understand the early thermal evolution and planetary scale differentiation of icy bodies with the radii in the range of 100-2500 km. These icy bodies include trans-Neptunian objects, minor icy planets (e.g., Ceres, Pluto); the icy satellites of Jupiter, Saturn, Uranus, and Neptune; and probably the icy-rocky cores of these planets. The decay energy of the radionuclides, 26Al, 60Fe, 40K, 235U, 238U, and 232Th, along with the impact-induced heating during the accretion of icy bodies were taken into account to thermally evolve these planetary bodies. The simulations were performed for a wide range of initial ice and rock (dust) mass fractions of the icy bodies. Three distinct accretion scenarios were used. The sinking of the rock mass fraction in primitive water oceans produced by the substantial melting of ice could lead to planetary scale differentiation with the formation of a rocky core that is surrounded by a water ocean and an icy crust within the initial tens of millions of years of the solar system in case the planetary bodies accreted prior to the substantial decay of 26Al. However, over the course of billions of years, the heat produced due to 40K, 235U, 238U, and 232Th could have raised the temperature of the interiors of the icy bodies to the melting point of iron and silicates, thereby leading to the formation of an iron core. Our simulations indicate the presence of an iron core even at the center of icy bodies with radii ≥500 km for different ice mass fractions.

Exploration of Icy Moons in the Outer Solar System: Updated Planetary Protection Requirements for Missions to Enceladus and Europa

NASA Astrophysics Data System (ADS)

Rummel, J. D.; Race, M. S.

2016-12-01

Enceladus and Europa are bodies with icy/watery environments and potential habitable conditions for life, making both of great interest in astrobiological studies of chemical evolution and /or origin of life. They are also of significant planetary protection concern for spacecraft missions because of the potential for harmful contamination during exploration. At a 2015 COSPAR colloquium in Bern Switzerland, international scientists identified an urgent need to establish planetary protection requirements for missions proposing to return samples to Earth from Saturn's moon Enceladus. Deliberations at the meeting resulted in recommended policy updates for both forward and back contamination requirements for missions to Europa and Enceladus, including missions sampling plumes originating from those bodies. These recently recommended COSPAR policy revisions and biological contamination requirements will be applied to future missions to Europa and Encealadus, particularly noticeable in those with plans for in situ life detection and sample return capabilities. Included in the COSPAR policy are requirementsto `break the chain of contact' with Europa or Enceladus, to keep pristine returned materials contained, and to complete required biohazard analyses, testing and/or sterilization upon return to Earth. Subsequent to the Bern meeting, additional discussions of Planetary Protection of Outer Solar System bodies (PPOSS) are underway in a 3-year study coordinated by the European Science Foundation and involving multiple international partners, including Japan, China and Russia, along with a US observer. This presentation will provide science and policy updates for those whose research or activities will involve icy moon missions and exploration.

JUICE: A European mission to explore the emergence of habitable worlds around gas giants

NASA Astrophysics Data System (ADS)

Witasse, O.

2017-09-01

JUICE - JUpiter ICy moons Explorer - is the first large mission in the ESA Cosmic Vision 2015-2025 programme. The mission was selected in May 2012 and adopted in November 2014. The implementation phase started in July 2015, following the selection of the prime industrial contractor, Airbus Defense and Space (Toulouse, France). Due to launch in June 2022 and arrival at Jupiter in October 2029, it will spend at least three ½ years making detailed observations of Jupiter and three of its largest moons, Ganymede, Callisto and Europa.

An Impacting Descent Probe for Europa and the Other Galilean Moons of Jupiter

NASA Astrophysics Data System (ADS)

Wurz, P.; Lasi, D.; Thomas, N.; Piazza, D.; Galli, A.; Jutzi, M.; Barabash, S.; Wieser, M.; Magnes, W.; Lammer, H.; Auster, U.; Gurvits, L. I.; Hajdas, W.

2017-08-01

We present a study of an impacting descent probe that increases the science return of spacecraft orbiting or passing an atmosphere-less planetary bodies of the solar system, such as the Galilean moons of Jupiter. The descent probe is a carry-on small spacecraft (<100 kg), to be deployed by the mother spacecraft, that brings itself onto a collisional trajectory with the targeted planetary body in a simple manner. A possible science payload includes instruments for surface imaging, characterisation of the neutral exosphere, and magnetic field and plasma measurement near the target body down to very low-altitudes ( 1 km), during the probe's fast ( km/s) descent to the surface until impact. The science goals and the concept of operation are discussed with particular reference to Europa, including options for flying through water plumes and after-impact retrieval of very-low altitude science data. All in all, it is demonstrated how the descent probe has the potential to provide a high science return to a mission at a low extra level of complexity, engineering effort, and risk. This study builds upon earlier studies for a Callisto Descent Probe for the former Europa-Jupiter System Mission of ESA and NASA, and extends them with a detailed assessment of a descent probe designed to be an additional science payload for the NASA Europa Mission.

Juno on Jupiter Doorstep

NASA Image and Video Library

2016-06-24

NASA's Juno spacecraft obtained this color view on June 21, 2016, at a distance of 6.8 million miles (10.9 million kilometers) from Jupiter. As Juno makes its initial approach, the giant planet's four largest moons -- Io, Europa, Ganymede and Callisto -- are visible, and the alternating light and dark bands of the planet's clouds are just beginning to come into view. Juno is approaching over Jupiter's north pole, affording the spacecraft a unique perspective on the Jupiter system. Previous missions that imaged Jupiter on approach saw the system from much lower latitudes, closer to the planet's equator. The scene was captured by the mission's imaging camera, called JunoCam, which is designed to acquire high resolution views of features in Jupiter's atmosphere from very close to the planet. http://photojournal.jpl.nasa.gov/catalog/PIA20701

Cost-Effective Icy Bodies Exploration using Small Satellite Missions

NASA Technical Reports Server (NTRS)

Jonsson, Jonas; Mauro, David; Stupl, Jan; Nayak, Michael; Aziz, Jonathan; Cohen, Aaron; Colaprete, Anthony; Dono-Perez, Andres; Frost, Chad; Klamm, Benjamin;

Virtual observatory tools and amateur radio observations supporting scientific analysis of Jupiter radio emissions

NASA Astrophysics Data System (ADS)

Cecconi, Baptiste; Hess, Sebastien; Le Sidaner, Pierre; Savalle, Renaud; Stéphane, Erard; Coffre, Andrée; Thétas, Emmanuel; André, Nicolas; Génot, Vincent; Thieman, Jim; Typinski, Dave; Sky, Jim; Higgins, Chuck; Imai, Masafumi

2016-04-01

In the frame of the preparation of the NASA/JUNO and ESA/JUICE (Jupiter Icy Moon Explorer) missions, and the development of a planetary sciences virtual observatory (VO), we are proposing a new set of tools directed to data providers as well as users, in order to ease data sharing and discovery. We will focus on ground based planetary radio observations (thus mainly Jupiter radio emissions), trying for instance to enhance the temporal coverage of jovian decametric emission. The data service we will be using is EPN-TAP, a planetary science data access protocol developed by Europlanet-VESPA (Virtual European Solar and Planetary Access). This protocol is derived from IVOA (International Virtual Observatory Alliance) standards. The Jupiter Routine Observations from the Nancay Decameter Array are already shared on the planetary science VO using this protocol, as well as data from the Iitate Low Frquency Radio Antenna, in Japan. Amateur radio data from the RadioJOVE project is also available. The attached figure shows data from those three providers. We will first introduce the VO tools and concepts of interest for the planetary radioastronomy community. We will then present the various data formats now used for such data services, as well as their associated metadata. We will finally show various prototypical tools that make use of this shared datasets.

Thermal Conductivity Measurements on Icy Satellite Analogs

NASA Technical Reports Server (NTRS)

Javeed, Aurya; Barmatz, Martin; Zhong, Fang; Choukroun, Mathieu

2012-01-01

With regard to planetary science, NASA aspires to: "Advance scientific knowledge of the origin and history of the solar system, the potential for life elsewhere, and the hazards and resources present as humans explore space". In pursuit of such an end, the Galileo and Cassini missions garnered spectral data of icy satellite surfaces implicative of the satellites' structure and material composition. The potential for geophysical modeling afforded by this information, coupled with the plausibility of life on icy satellites, has pushed Jupiter's Europa along with Saturn's Enceladus and Titan toward the fore of NASA's planetary focus. Understanding the evolution of, and the present processes at work on, the aforementioned satellites falls squarely in-line with NASA's cited goal.

Seeding Life on the Moons of the Outer Planets via Lithopanspermia

PubMed Central

Sigurdsson, Steinn; House, Christopher H.

2013-01-01

Abstract Material from the surface of a planet can be ejected into space by a large impact and could carry primitive life-forms with it. We performed n-body simulations of such ejecta to determine where in the Solar System rock from Earth and Mars may end up. We found that, in addition to frequent transfer of material among the terrestrial planets, transfer of material from Earth and Mars to the moons of Jupiter and Saturn is also possible, but rare. We expect that such transfers were most likely to occur during the Late Heavy Bombardment or during the ensuing 1–2 billion years. At this time, the icy moons were warmer and likely had little or no ice shell to prevent meteorites from reaching their liquid interiors. We also note significant rates of re-impact in the first million years after ejection. This could re-seed life on a planet after partial or complete sterilization by a large impact, which would aid the survival of early life during the Late Heavy Bombardment. Key Words: Panspermia—Impact—Meteorites—Titan—Europa. Astrobiology 13, 1155–1165. PMID:24341459

The Radio & Plasma Wave Investigation (RPWI) for JUICE

NASA Astrophysics Data System (ADS)

Wahlund, J.-E.

2013-09-01

We present the Radio & Plasma Waves Investigation (RPWI) selected for implementation on the JUICE mission. RPWI consists of a highly integrated instrument package that provides a whole set of plasma and fields measurements. The RPWI instrument has outstanding new capabilities not previously available to outer planet missions, and that would address many fundamental planetary science objectives. Specifically, RPWI would be able to study the electro-dynamic influence of the Jovian magnetosphere on the exospheres, surfaces and conducting oceans of Ganymede, Europa and Callisto. RPWI would also be able to monitor the sources of radio emissions from auroral regions of Ganymede and Jupiter, and possibly also from lightning activity in Jupiter's clouds. Moreover, RPWI will search for exhaust plumes from cracks on the icy moons, as well as μm-sized dust and related dust-plasmasurface interaction processes occurring near the icy moons of Jupiter.

HUBBLE CLICKS IMAGES OF IO SWEEPING ACROSS JUPITER

NASA Technical Reports Server (NTRS)

2002-01-01

While hunting for volcanic plumes on Io, NASA's Hubble Space Telescope captured these images of the volatile moon sweeping across the giant face of Jupiter. Only a few weeks before these dramatic images were taken, the orbiting telescope snapped a portrait of one of Io's volcanoes spewing sulfur dioxide 'snow.' These stunning images of the planetary duo are being released to commemorate the ninth anniversary of the Hubble telescope's launch on April 24, 1990. All of these images were taken with the Wide Field and Planetary Camera 2. The three overlapping snapshots show in crisp detail Io passing above Jupiter's turbulent clouds. The close-up picture of Io (bottom right) reveal a 120-mile-high (200-kilometer) plume of sulfur dioxide 'snow' emanating from Pillan, one of the moon's active volcanoes. 'Other observations have inferred sulfur dioxide 'snow' in Io's plumes, but this image offers direct observational evidence for sulfur dioxide 'snow' in an Io plume,' explains John R. Spencer of Lowell Observatory in Flagstaff, Ariz. A Trip Around Jupiter The three snapshots of the volcanic moon rounding Jupiter were taken over a 1.8-hour time span. Io is roughly the size of Earth's moon but 2,000 times farther away. In two of the images, Io appears to be skimming Jupiter's cloud tops, but it's actually 310,000 miles (500,000 kilometers) away. Io zips around Jupiter in 1.8 days, whereas the moon circles Earth every 28 days. The conspicuous black spot on Jupiter is Io's shadow and is about the size of the moon itself (2,262 miles or 3,640 kilometers across). This shadow sails across the face of Jupiter at 38,000 mph (17 kilometers per second). The smallest details visible on Io and Jupiter measure 93 miles (150 kilometers) across, or about the size of Connecticut. These images were further sharpened through image reconstruction techniques. The view is so crisp that one would have to stand on Io to see this much detail on Jupiter with the naked eye. The bright patches on Io

Hubble Clicks Images of Io Sweeping Across Jupiter

NASA Technical Reports Server (NTRS)

1999-01-01

While hunting for volcanic plumes on Io, NASA's Hubble Space Telescope captured these images of the volatile moon sweeping across the giant face of Jupiter. Only a few weeks before these dramatic images were taken, the orbiting telescope snapped a portrait of one of Io's volcanoes spewing sulfur dioxide 'snow.'

These stunning images of the planetary duo are being released to commemorate the ninth anniversary of the Hubble telescope's launch on April 24, 1990. All of these images were taken with the Wide Field and Planetary Camera 2.

The three overlapping snapshots show in crisp detail Io passing above Jupiter's turbulent clouds. The close-up picture of Io (bottom right) reveal a 120-mile-high (200-kilometer) plume of sulfur dioxide 'snow' emanating from Pillan, one of the moon's active volcanoes.

'Other observations have inferred sulfur dioxide 'snow' in Io's plumes, but this image offers direct observational evidence for sulfur dioxide 'snow' in an Io plume,' explains John R. Spencer of Lowell Observatory in Flagstaff, Ariz.

A Trip Around Jupiter

The three snapshots of the volcanic moon rounding Jupiter were taken over a 1.8-hour time span. Io is roughly the size of Earth's moon but 2,000 times farther away. In two of the images, Io appears to be skimming Jupiter's cloud tops, but it's actually 310,000 miles (500,000 kilometers) away. Io zips around Jupiter in 1.8 days, whereas the moon circles Earth every 28 days.

The conspicuous black spot on Jupiter is Io's shadow and is about the size of the moon itself (2,262 miles or 3,640 kilometers across). This shadow sails across the face of Jupiter at 38,000 mph (17 kilometers per second). The smallest details visible on Io and Jupiter measure 93 miles (150 kilometers) across, or about the size of Connecticut.

These images were further sharpened through image reconstruction techniques. The view is so crisp that one would have to stand on Io to see this much detail on Jupiter with the naked eye

Natural radio emission of Jupiter as interferences for radar investigations of the icy satellites of Jupiter

NASA Astrophysics Data System (ADS)

Cecconi, B.; Hess, S.; Hérique, A.; Santovito, M. R.; Santos-Costa, D.; Zarka, P.; Alberti, G.; Blankenship, D.; Bougeret, J.-L.; Bruzzone, L.; Kofman, W.

2012-02-01

Radar instruments are part of the core payload of the two Europa Jupiter System Mission (EJSM) spacecraft: NASA-led Jupiter Europa Orbiter (JEO) and ESA-led Jupiter Ganymede Orbiter (JGO). At this point of the project, several frequency bands are under study for radar, which ranges between 5 and 50 MHz. Part of this frequency range overlaps with that of the natural jovian radio emissions, which are very intense in the decametric range, below 40 MHz. Radio observations above 40 MHz are free of interferences, whereas below this threshold, careful observation strategies have to be investigated. We present a review of spectral intensity, variability and sources of these radio emissions. As the radio emissions are strongly beamed, it is possible to model the visibility of the radio emissions, as seen from the vicinity of Europa or Ganymede. We have investigated Io-related radio emissions as well as radio emissions related to the auroral oval. We also review the radiation belts synchrotron emission characteristics. We present radio sources visibility products (dynamic spectra and radio source location maps, on still frames or movies), which can be used for operation planning. This study clearly shows that a deep understanding of the natural radio emissions at Jupiter is necessary to prepare the future EJSM radar instrumentation. We show that this radio noise has to be taken into account very early in the observation planning and strategies for both JGO and JEO. We also point out possible synergies with RPW (Radio and Plasma Waves) instrumentations.

Natural radio emission of Jupiter as interferences for radar investigations of the icy satellites of Jupiter

NASA Astrophysics Data System (ADS)

Cecconi, B.; Hess, S.; Hérique, A.; Santovito, M. R.; Santos-Costa, D.; Zarka, P.; Alberti, G.; Blankenship, D.; Bougeret, J. L.; Bruzzone, L.; Kofman, W.

2011-10-01

Radar instruments are part of the core payload of the two Europa Jupiter System Mission (EJSM) spacecraft: NASA-led Jupiter Europa Orbiter (JEO) and ESA-led Jupiter Ganymede Orbiter (JGO). At this point of the project, several frequency bands are under study for radar, which ranges between 5MHz and 50MHz. Part of this frequency range overlaps with that of the natural Jovian radio emissions, which are very intense in the decametric range, below 40 MHz. Radio observations above 40 MHz are free of interferences, whereas below this threshold, careful observation strategies have to be investigated. We present a review of spectral intensity, variability and sources of these radio emissions. As the radio emission are strongly beamed, it is possible to model the visibility of the radio emissions, as seen from the vicinity of Europa or Ganymede. We have investigated Io-related radio emissions as well as radio emissions related to the auroral oval. We also review the radiation belts synchrotron emission characteristics. We present radio sources visibility products (dynamic spectra and radio source location maps, on still frames or movies), which can be used for operation planning. This study clearly shows that a deep understanding of the natural radio emissions at Jupiter is necessary to prepare the future EJSM radar instrumentation. We show that this radio noise has to be taken into account very early in the observation planning and strategies for both JGO and JEO. We also point out possible synergies with RPW (Radio and Plasma Waves) instrumentations.

Family Portrait of Jupiter Great Red Spot and the Galilean Satellites

NASA Image and Video Library

1997-11-18

This "family portrait," a composite of the Jovian system, includes the edge of Jupiter with its Great Red Spot, and Jupiter's four largest moons, known as the Galilean satellites. From top to bottom, the moons shown are Io, Europa, Ganymede and Callisto. The Great Red Spot, a storm in Jupiter's atmosphere, is at least 300 years old. Winds blow counterclockwise around the Great Red Spot at about 400 kilometers per hour (250 miles per hour). The storm is larger than one Earth diameter from north to south, and more than two Earth diameters from east to west. In this oblique view, the Great Red Spot appears longer in the north-south direction. Europa, the smallest of the four moons, is about the size of Earth's moon, while Ganymede is the largest moon in the solar system. North is at the top of this composite picture in which the massive planet and its largest satellites have all been scaled to a common factor of 15 kilometers (9 miles) per picture element. The Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft obtained the Jupiter, Io and Ganymede images in June 1996, while the Europa images were obtained in September 1996. Because Galileo focuses on high resolution imaging of regional areas on Callisto rather than global coverage, the portrait of Callisto is from the 1979 flyby of NASA's Voyager spacecraft. http://photojournal.jpl.nasa.gov/catalog/PIA00600

OASIS: Organics Analyzer for Sampling Icy Surfaces

NASA Technical Reports Server (NTRS)

Getty, S. A.; Dworkin, J. P.; Glavin, D. P.; Martin, M.; Zheng, Y.; Balvin, M.; Southard, A. E.; Ferrance, J.; Malespin, C.

2012-01-01

Liquid chromatography mass spectrometry (LC-MS) is a well established laboratory technique for detecting and analyzing organic molecules. This approach has been especially fruitful in the analysis of nucleobases, amino acids, and establishing chirol ratios [1 -3]. We are developing OASIS, Organics Analyzer for Sampling Icy Surfaces, for future in situ landed missions to astrochemically important icy bodies, such as asteroids, comets, and icy moons. The OASIS design employs a microfabricated, on-chip analytical column to chromatographically separate liquid ana1ytes using known LC stationary phase chemistries. The elution products are then interfaced through electrospray ionization (ESI) and analyzed by a time-of-flight mass spectrometer (TOF-MS). A particular advantage of this design is its suitability for microgravity environments, such as for a primitive small body.

Earth Moon

NASA Image and Video Library

1998-06-08

NASA Galileo spacecraft took this image of Earth moon on December 7, 1992 on its way to explore the Jupiter system in 1995-97. The distinct bright ray crater at the bottom of the image is the Tycho impact basin. http://photojournal.jpl.nasa.gov/catalog/PIA00405

Jupiter and the Voyager mission

USGS Publications Warehouse

Soderblom, L.; Spall, Henry

1980-01-01

In 1977, the United States launched two unmanned Voyager spacecraft that were to take part in an extensive reconnaissance of the outer planets over a 12-year period visiting the environs of Jupiter, Saturn, Uranus, and Neptune. Their first encounter was with the complex Jupiter planetary system 400 million miles away. Sweeping by Jupiter and its five moons in 1979, the two spacecraft have sent back to Earth an enormous amount of data that will prove to be vital in understanding our solar system. Voyager 1 is scheduled to fly past Saturn on November 13 of this year; Voyager 2, in August of the following year. 

Planetary Analogs in Antarctica: Icy Satellites

NASA Technical Reports Server (NTRS)

Malin, M. C.

1985-01-01

As part of a study to provide semi-quantitative techniques to date past Antarctic glaciations, sponsored by the Antarctic Research Program, field observations pertinent to other planets were also acquired. The extremely diverse surface conditions, marked by extreme cold and large amounts of ice, provide potential terrain and process analogs to the icy satellites of Jupiter and Saturn. Thin ice tectonic features and explosion craters (on sea ice) and deformation features on thicker ice (glaciers) are specifically addressed.

Experimental study of IR-signature of water ices between 1 and 2.5 µm : a thermal probe for icy moons

NASA Astrophysics Data System (ADS)

Taffin, C.; Grasset, O.; Le Menn, E.; Le Mouélic, S.

2009-12-01

Near IR signatures of water ices are known to depend on temperature and grain size, a property that could be used to constrain the surface characteristics of icy moons1,2,3. Models indicate that the 1.65 µm absorption band depends strongly on temperature2,4,5 and on grain size. Other bands (1.03, 1.27, 1.50 and 2 µm) show a strong dependence with grain size (e.g. (6) for the 1.03 µm band). But the respective influence of temperature and grain size is still not fully understood. In this work, we focus on the 1.50 and 1.55 µm absorption bands. Characteristics of near-IR spectra of pure ice Ih grains have been experimentally investigated using temperature and pressure ranges relevant for icy moons. Nineteen experiments have been conducted both at microscopic (individual grains smaller than 100 mm) and macroscopic (grains ranging from 200 to 800 µm) scales, using a FTIR spectrometer. Position, area and depth of the four main absorption bands in the near-IR domain (1.50, 1.55, 1.65 and 2 µm) have been studied . It will be shown that the positions of the 1.50 µm and the 1.55 µm bands are very good indicators of grain size and of temperature, respectively (Fig.1). The scaling laws established from experimental data can be used to characterize the surface properties of icy moons. Preliminary tests are conducted on extensively studied regions to validate the approach. An application to the Tiger Stripes on Enceladus will be presented. The estimated temperatures are at first order consistent with those obtained by CIRS7, but they still appear slightly higher in average (between 10 and 20 K). Grain size are also bigger than in a previous model8 but the same tendency is observed, i.e., the grain size is larger on the Tiger Stripes than in the surroundings. Ref. : 1-Fink and Larson, Icarus, 1975. 2-Leto et al. Mem. S.A.It. Suppl. 2005. 3-Grundy, Icarus, 1999. 4-Grundy and Schmitt, JGR. 1998. 5-Mastrapa et al. Icarus, 2008. 6-Nolin and Dozier Rem. Sens. Environ. 2000. 7

Galileo's Telescopy and Jupiter's Tablet

NASA Astrophysics Data System (ADS)

Usher, P. D.

2003-12-01

A previous paper (BAAS 33:4, 1363, 2001) reported on the dramatic scene in Shakespeare's Cymbeline that features the descent of the deity Jupiter. The paper suggested that the four ghosts circling the sleeping Posthumus denote the four Galilean moons of Jupiter. The god Jupiter commands the ghosts to lay a tablet upon the prone Posthumus, but says that its value should not be overestimated. When Posthumus wakens he notices the tablet, which he calls a "book." Not only has the deity's "tablet" become the earthling's "book," but it appears that the book has covers which Posthumus evidently recognizes because without even opening the book he ascribes two further properties to it: rarity, and the very property that Jupiter had earlier attributed, viz. that one must not read too much into it. The mystery deepens when the Jovian gift undergoes a second metamorphosis, to "label." With the help of the OED, the potentially disparate terms "tablet," "book," and "label," may be explained by terms appropriate either to supernatural or worldly beings. "Tablet" may recognize the Mosaic artifact, whereas "book" and "label" are probably mundane references to Galileo's Sidereus Nuncius which appeared shortly before Cymbeline. The message of the Olympian god indicates therefore that the book is unique even as its contents have limited value. The first property celebrates the fact that Galileo's book is the first of its kind, and the second advises that all results except the discovery of Jupiter's moons have been reported earlier, in Hamlet.

Hubble Sees Recurring Plume Erupting From Europa

NASA Image and Video Library

2017-04-13

These composite images show a suspected plume of material erupting two years apart from the same location on Jupiter's icy moon Europa. The images bolster evidence that the plumes are a real phenomenon, flaring up intermittently in the same region on the satellite. Both plumes, photographed in ultraviolet light by NASA's Hubble's Space Telescope Imaging Spectrograph, were seen in silhouette as the moon passed in front of Jupiter. The newly imaged plume, shown at right, rises about 62 miles (100 kilometers) above Europa's frozen surface. The image was taken Feb. 22, 2016. The plume in the image at left, observed by Hubble on March 17, 2014, originates from the same location. It is estimated to be about 30 miles (50 kilometers) high. The snapshot of Europa, superimposed on the Hubble image, was assembled from data from NASA's Galileo mission to Jupiter. The plumes correspond to the location of an unusually warm spot on the moon's icy crust, seen in the late 1990s by the Galileo spacecraft (see PIA21444). Researchers speculate that this might be circumstantial evidence for water venting from the moon's subsurface. The material could be associated with the global ocean that is believed to be present beneath the frozen crust. https://photojournal.jpl.nasa.gov/catalog/PIA21443

Hubble Images Reveal Jupiter's Auroras

NASA Technical Reports Server (NTRS)

1996-01-01

These images, taken by the Hubble Space Telescope, reveal changes in Jupiter's auroral emissions and how small auroral spots just outside the emission rings are linked to the planet's volcanic moon, Io. The images represent the most sensitive and sharply-detailed views ever taken of Jovian auroras.

The top panel pinpoints the effects of emissions from Io, which is about the size of Earth's moon. The black-and-white image on the left, taken in visible light, shows how Io and Jupiter are linked by an invisible electrical current of charged particles called a 'flux tube.' The particles - ejected from Io (the bright spot on Jupiter's right) by volcanic eruptions - flow along Jupiter's magnetic field lines, which thread through Io, to the planet's north and south magnetic poles. This image also shows the belts of clouds surrounding Jupiter as well as the Great Red Spot.

The black-and-white image on the right, taken in ultraviolet light about 15 minutes later, shows Jupiter's auroral emissions at the north and south poles. Just outside these emissions are the auroral spots. Called 'footprints,' the spots are created when the particles in Io's 'flux tube' reach Jupiter's upper atmosphere and interact with hydrogen gas, making it fluoresce. In this image, Io is not observable because it is faint in the ultraviolet.

The two ultraviolet images at the bottom of the picture show how the auroral emissions change in brightness and structure as Jupiter rotates. These false-color images also reveal how the magnetic field is offset from Jupiter's spin axis by 10 to 15 degrees. In the right image, the north auroral emission is rising over the left limb; the south auroral oval is beginning to set. The image on the left, obtained on a different date, shows a full view of the north aurora, with a strong emission inside the main auroral oval.

The images were taken by the telescope's Wide Field and Planetary Camera 2 between May 1994 and September 1995.

This image and

Connecting LADEE LDEX Observations of the Moon's dust cloud to the temporal and selenographic variability produced by micrometeoroid impacts from Jupiter Family Comets

NASA Astrophysics Data System (ADS)

Janches, D.; Pokorny, P.; Sarantos, M.; Nesvorny, D.

2017-12-01

Recent observations by the Lunar Dust Experiment (LDEX) on board NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) were perceived to indicate an unbalanced influence of meteoroids impacting from the Helion and the Anti-Helion directions. These observations were interpreted without proper consideration of the dynamical characteristics of the meteoroid environment and its spatio-temporal influence on the Moon's surface. In this work, a dynamical model of meteoroids originating from Jupiter Family Comets is utilized to model the secondary dust ejecta cloud engulfing the Moon. It is shown that the combination of the dynamical properties of these meteoroids, together with the orbital geometry of LADEE, introduce a bias in the observations and causes LADEE LDEX to be more sensitive to the Helion source. This effect must be considered in order to draw accurate conclusions regarding the meteoroid environment and its influence on the Moon's surface.

The Portrayal of the Medicean Moons in Early Astronomical Charts and Books

NASA Astrophysics Data System (ADS)

Mendillo, Michael

2014-06-01

Galileo’s talents in perspective and chiaroscuro drawing led to his images of the Moon being accepted as the portrayal of a truly natural physical place. The Moon was seen as a world—real but separate from Earth. In contrast to his resolved views of the Moon, Galileo saw the moons of Jupiter as only points of light, and thus in Sidereus Nuncius they appear as star-symbols. Within 50 years, in Cellarius’ Atlas Coelestis seu Harmonia Macrocosmica (1660), the Medicean moons continue to appear in multiple charts as star-shaped symbols—in most cases equidistant from Jupiter. They appear in the Cellarius charts as updates to the cosmological systems of Copernicus and Tycho Brahe, but not in the charts devoted to the Ptolemaic system. A quarter century later, Mallet did not include the moons of Jupiter in his Copernican chart in Description de l’Universe (1683). Around 1690, in Jaillot’s Four Systems of Cosmology, the Medicean moons appear as circular symbols in four distinct concentric orbits around Jupiter. Additional examples appear in a later edition of Mallet ((1690s), and in De Fer (1705), Dopplemayer (1720), and still later in Buy de Mornas (1761). As objects discussed in scientific book, symbolic representations of the Medicean moons appear in Marius (1614), Descartes (1644), Fontana (1646) and Hevelius (1647). A pictorial survey of antiquarian charts and books depicting the Medicean moons will be the focus of this presentation. As telescope sizes increased, the Galilean moons could be seen as extended objects, and thus the transition occurred from portraying the moons as points of light to disks with physically-meaningful details. Initially, these were done via drawings of glimpses of the disks of the four moons during moments of extremely good seeing (termed “lucky images” in the pre-adaptive optics period). This era of portraying surface characteristics of Io, Europa, Ganymede and Callisto by hand-drawn images from naked-eye observations ended

ScienceCast 38: The Great Lakes of Europa

NASA Image and Video Library

2011-11-23

Scientists studying data from NASA's Galileo probe have discovered what appears to be a body of liquid water the volume of the North American Great Lakes locked inside the icy shell of Jupiter's moon Europa.

Storms and Moons

NASA Technical Reports Server (NTRS)

2007-01-01

The New Horizons Long Range Reconnaissance Imager (LORRI) took this 2-millisecond exposure of Jupiter at 04:41:04 UTC on January 24, 2007. The spacecraft was 57 million kilometers (35.3 million miles) from Jupiter, closing in on the giant planet at 41,500 miles (66,790 kilometers) per hour. At right are the moons Io (bottom) and Ganymede; Ganymede's shadow creeps toward the top of Jupiter's northern hemisphere.

Two of Jupiter's largest storms are visible; the Great Red Spot on the western (left) limb of the planet, trailing the Little Red Spot on the eastern limb, at slightly lower latitude. The Great Red Spot is a 300-year old storm more than twice the size of Earth. The Little Red Spot, which formed over the past decade from the merging of three smaller storms, is about half the size of its older and 'greater' counterpart.

Juno Observes Jupiter, Io and Europa

NASA Image and Video Library

2017-10-06

This color-enhanced image of Jupiter and two of its largest moons -- Io and Europa -- was captured by NASA's Juno spacecraft as it performed its eighth flyby of the gas giant planet. The image was taken on Sept. 1, 2017 at 3:14 p.m. PDT (6:14 p.m. EDT). At the time the image was taken, the spacecraft was about 17,098 miles (27,516 kilometers) from the tops of the clouds of the planet at a latitude of minus 49.372 degrees. Closer to the planet, the Galilean moon of Io can be seen at an altitude of 298,880 miles (481,000 kilometers) and at a spatial scale of 201 miles (324 kilometers) per pixel. In the distance (to the left), another one of Jupiter's Galilean moons, Europa, is visible at an altitude of 453,601 miles (730,000 kilometers) and at a spatial scale of 305 miles (492 kilometers) per pixel. Citizen scientist Roman Tkachenko processed this image using data from the JunoCam imager. https://photojournal.jpl.nasa.gov/catalog/PIA21968

Thermal Conductive Heat Transfer and Partial Melting of Volatiles in Icy Moons, Asteroids, and Kuiper Belt Objects (Invited)

NASA Astrophysics Data System (ADS)

Kargel, J. S.; Furfaro, R.

2013-12-01

Thermal gradients within conductive layers of icy satellite and asteroids depend partly on heat flow, which is related to the secular decay of radioactive isotopes, to heat released by chemical phase changes, by conversion of gravitational potential energy to heat during differentiation, tidal energy dissipation, and to release of heat stored from prior periods. Thermal gradients are also dependent on the thermal conductivity of materials, which in turn depends on their composition, crystallinity, porosity, crystal fabric anisotropy, and details of their mixture with other materials. Small impurities can produce lattice defects and changes in polymerization, and thereby have a huge influence on thermal conductivity, as can cage-inclusion (clathrate) compounds. Heat flow and thermal gradients can be affected by fluid phase advection of mass and heat (in oceans or sublimating upper crusts), by refraction related to heterogeneities of thermal conductivity due to lateral variations and composition or porosity. Thermal profiles depend also on the surface temperature controlled by albedo and climate, surface relief, and latitude, orbital obliquity and surface insolation, solid state greenhouses, and endogenic heating of the surface. The thermal state of icy moon interiors and thermal gradients can be limited at depth by fluid phase advection of heat (e.g., percolating meteoric methane or gas emission), by the latent heat of phase transitions (melting, solid-state transitions, and sublimation), by solid-state convective or diapiric heat transfer, and by foundering. Rapid burial of thick volatile deposits can also affect thermal gradients. For geologically inactive or simple icy objects, most of these controls on heat flow and thermal gradients are irrelevant, but for many other icy objects they can be important, in some cases causing large lateral and depth variations in thermal gradients, large variations in heat flow, and dynamically evolving thermal states. Many of

The Longevity of Water Ice on Ganymedes and Europas around Migrated Giant Planets

NASA Astrophysics Data System (ADS)

Lehmer, Owen R.; Catling, David C.; Zahnle, Kevin J.

2017-04-01

The gas giant planets in the Solar System have a retinue of icy moons, and we expect giant exoplanets to have similar satellite systems. If a Jupiter-like planet were to migrate toward its parent star the icy moons orbiting it would evaporate, creating atmospheres and possible habitable surface oceans. Here, we examine how long the surface ice and possible oceans would last before being hydrodynamically lost to space. The hydrodynamic loss rate from the moons is determined, in large part, by the stellar flux available for absorption, which increases as the giant planet and icy moons migrate closer to the star. At some planet-star distance the stellar flux incident on the icy moons becomes so great that they enter a runaway greenhouse state. This runaway greenhouse state rapidly transfers all available surface water to the atmosphere as vapor, where it is easily lost from the small moons. However, for icy moons of Ganymede’s size around a Sun-like star we found that surface water (either ice or liquid) can persist indefinitely outside the runaway greenhouse orbital distance. In contrast, the surface water on smaller moons of Europa’s size will only persist on timescales greater than 1 Gyr at distances ranging 1.49-0.74 au around a Sun-like star for Bond albedos of 0.2 and 0.8, where the lower albedo becomes relevant if ice melts. Consequently, small moons can lose their icy shells, which would create a torus of H atoms around their host planet that might be detectable in future observations.

Photographer : JPL Range : 7 million kilometers (5 million miles) Callisto is Jupiter's outermost

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 7 million kilometers (5 million miles) Callisto is Jupiter's outermost Galilean satellites and darkest of the four(but almost twice as bright as Earth's Moon). Mottled appearance from bright and dark patches. Bright spots seem like rayed or bright halved craters seen on our Moon. This face is always turned toward Jupiter. Photo taken through violet filter. Ganymede is slightly larger than Mercury but much less dense (twice the density of water). Its surface brightness is 4 times of Earth's Moon. Mare regions (dark features) are like the Moon's but have twice the brightness, and believed to be unlikely of rock or lava as the Moon's are. It's north pole seems covered with brighter material and may be water frost. Scattered brighter spots may be related to impact craters or source of fresh ice.

Medium-sized icy satellites in the outer solar system - differentiation due to radiogenic heating in Charon or the moons of Uranus?

NASA Astrophysics Data System (ADS)

Multhaup, K.; Spohn, T.

2007-08-01

A thermal history model developed for medium-sized icy satellites containing silicate rock at low volume fractions is applied to Charon and five satellites of Uranus. The model assumes stagnant lid convection in homogeneously accreted bodies either confined to a spherical shell or encompassing the whole interior below the immobile surface layer. We employ a simple model for accretion assuming that infalling planetesimals deposit a fraction of their kinetic energy as heat at the instantaneous surface of the growing moon. Rheology parameters are chosen to match those of ice I, although the satellites under consideration likely contain admixtures of lighter constituents. Consequences thereof are discussed. Thermal evolution calculations considering radiogenic heating by long-lived isotopes suggest that Ariel, Umbriel, Titania, Oberon and Charon may have started to differentiate after a few hundred million years of evolution. Results for Miranda - the smallest satellite of Uranus - however, indicate that it never convected or differentiated. Miranda's interior temperature was found to be not even close to the melting temperatures of reasonable mixtures of water and ammonia. This finding is in contrast to its heavily modified surface and supports theories that propose alternative heating mechanisms such as early tidal heating. Except for Miranda, our results lend support to differentiated icy satellite models. We also point out parallels to previously published results obtained for several of Saturn's icy satellites (Multhaup and Spohn, 2007). The predicted early histories of Ariel, Umbriel and Charon are evocative of Dione's and Rhea's, while Miranda's resembles that of Mimas.

Ultraviolet Spectroscopy of the Surfaces of the Inner Icy Saturnian Satellites

NASA Astrophysics Data System (ADS)

Hendrix, A. R.; Hansen, C. J.

2008-12-01

The Cassini mission has provided a unique opportunity to make high-resolution, multi-spectral measurements of Saturn's icy moons, to investigate their surface compositions, processes and evolution. Here we present results from the Ultraviolet Imaing Spectrograph (UVIS). This instrument allows for the first measurements of the icy satellites in the extreme ultraviolet (EUV) to far-ultraviolet (FUV) wavelength range. The icy satellites of the Saturn system exhibit a remarkable amount of variability: Dark, battered Phoebe orbiting at a distant 200 RS, black-and-white Iapetus, the wispy streaks of Dione, cratered Rhea and Mimas, bright Tethys and geologically active Enceladus. Phoebe, Iapetus and Hyperion all orbit largely outside Saturn's magnetosphere, while the inner icy satellites Mimas, Enceladus, Dione Tethys and Rhea all orbit within the magnetosphere. Furthermore, the inner icy satellites all orbit within the E-ring - so the extent of exogenic effects on these icy satellites is wide-ranging. We present an overview of UVIS results from Tethys, Dione, Mimas, Enceladus and Rhea, focusing on surface investigations. We expect that the UV signatures of these icy satellites are strongly influenced not only by their water ice composition, but by external effects and magnetospheric environments. We study the FUV reflectance spectra to learn about the surface composition, map out water ice grain size variations, investigate effects of coating by E-ring grains, examine disk-resolved and hemispheric compositional and brightness variations, and investigate the presence of radiation products. This is new work: FUV spectra of surfaces have not been well-studied in the past. Spectra of the inner icy moons have been used to better develop spectral models, to further understand existing lab data of water ice and to help with understanding instrument performance. Analysis is challenged by a lack of laboratory data in this wavelength region, but intriguing results are being found

The Saturnian moon Enceladus

NASA Technical Reports Server (NTRS)

1982-01-01

This high-resolution image of Enceladus was made from several images obtained Aug. 25, 1981, by Voyager 2 from a range of 119,000 kilometers (74,000 miles). It shows further surface detail on this Saturnian moon. Enceladus is seen to resemble Jupiter's moon Ganymede, which is, however, about 10 times larger. Faintly visible here in light reflected from Saturn is the hemisphere turned away from the sun. The Voyager project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.

Phase diagram and density of fluids in the water-methanol system: experiments and implications for the crystallization and dynamics of subsurface oceans in icy moons

NASA Astrophysics Data System (ADS)

Yao, C.; Mantegazzi, D.; Deschamps, F.; Sanchez-Valle, C.

2013-12-01

Methanol, CH3OH, has been recently observed in several comets and at the surface of Saturn's icy moon Enceladus, [Hodyss et al., 2009]. Its plausible presence in the subsurface ocean could significantly affect the thermal and structural evolution of the satellite [Deschamps et al., 2010]. Methanol lowers the melting temperature of water ice [Vuillard & Sanchez, 1961; Miller & Carpenter, 1964], hence decreasing the efficiency of convective heat transfer through the outer ice Ih shell, and affects the subsurface ocean density and thermo-chemical evolution. However, the phase diagram and the fluid density of the H2O - CH3OH system remains largely unknown at the high pressures and low temperature conditions relevant for the icy moon interiors. In this study, we determined experimentally the liquidus temperature of Ice Ih and Ice VI and the fluid density in the binary water-methanol system (5, 10 and 20 w% CH3OH) from sound velocity measurments by Brillouin scattering spectroscopy over the P-T range 230 - 300 K and 10-4 - 1.2 GPa. The experiments were conducted using a membrane-type diamond anvil cell (mDAC) and an in-house designed Peltier cooling system to achieve the low temperatures of interest. Melting and crystallization in the system was visually monitored and confirmed from changes in the Brillouin spectra and in the pressure dependence of the measured sound velocities. The density of fluids ρ(P, T,x) in the binary system weas determined from the inversion of sound velocities measured in the fluids as a function of pressure along isotherms from 230 to 300 K. The results are used to propose a thermodynamic model for the CH3OH-H2O system over the investigated P-T range and further used to examine the effect of the methanol on the crystallization and thermo-chemical evolution of the subsurface ocean. The implications of these results for the thermal and structural evolution of icy moons, with particular applications to Titan, will be further discussed. References

Jupiter - Io In Front of Jupiter Turbulent Clouds

NASA Image and Video Library

1996-11-13

This photograph of the southern hemisphere of Jupiter was obtained by Voyager 2 on June 25, 1979, at a distance of 12 million kilometers (8 million miles). The Voyager spacecraft is rapidly nearing the giant planet, with closest approach to occur at 4:23 pm PDT on July 9. Seen in front of the turbulent clouds of the planet is Io, the innermost of the large Galilean satellites of Jupiter. Io is the size of our moon. Voyager discovered in early March that Io is the most volcanically active planetary body known in the solar system, with continuous eruptions much larger than any that take place on the Earth. The red, orange, and yellow colors of Io are thought to be deposits of sulfur and sulfur compounds produced in these eruptions. The smallest features in either Jupiter or Io that can be distinguished in this picture are about 200 kilometers (125 miles) across; this resolution, it is not yet possible to identify individual volcanic eruptions. Monitoring of the erupture activity of Io by Voyager 2 will begin about July 5 and will extend past the encounter July 9. http://photojournal.jpl.nasa.gov/catalog/PIA00371

Volcanism on Jupiter's moon Io and its relation to interior processes

NASA Astrophysics Data System (ADS)

Hamilton, Christopher

2013-04-01

Jupiter's moon Io is the most volcanically active body in the Solar System and offers insight into processes of tidal heating, melt generation, and magma ascent. Investigating these processes contributes to a better understanding of Io's geologic history, internal structure, and tidal dissipation mechanisms, as well as to understanding similar processes operating on other tidally-heated worlds (e.g., Europa, Enceladus, and some exoplanets). Four recent developments provide new observational constraints that prompt re-examination of the relationships between Io's surficial geology and interior structure. These developments include: (1) completion of the first 1:15,000,000 scale geologic map of Io based on a synthesis of Voyager and Galileo data; (2) re-interpretation of Galileo magnetometer data, which suggests that Io has a globally continuous subsurface magma ocean; (3) new global surveys of the power output from volcanic centers on Io; and (4) identification of an offset between volcano concentrations and surface heat flux maxima predicted by solid body tidal heating models. In this study, the spatial distributions of volcanic hotspots and paterae on Io are characterized using distance-based clustering techniques and nearest neighbor statistics. Distance-based clustering results support a dominant role for asthenospheric heating within Io, but show a 30-60° eastward offset in volcano concentrations relative to locations of predicted surface heat flux maxima. The observed asymmetry in volcano concentrations, with respect to the tidal axis, cannot be explained by existing solid body tidal heating models. However, identification of a global magma ocean within Io raises the intriguing possibility that a fluid tidal response—analogous to the heating of icy satellites by fluid tidal dissipation in their liquid oceans—may modify Io's thermal budget and locations of enhanced volcanism. The population density of volcanoes is greatest near the equator, which also

Europa, taken from Voyager 1 to Jupiter

NASA Image and Video Library

1979-03-01

Range : 5.9 million kilometers (3.66 million miles) Europa is Jupiter's 2nd Galilean satellites from the planet and the brightest. Photo taken early morning through violet filter. Faint swirls and linear patterns show in the equatorial region (which shows darker than the poles). This hemisphere always faces Jupiter. North is up. Density and size comparable to Earth's Moon and seems to show water ice or ground water on its surface. JPL Reference # P-21163.

Jupiter, Tether, and Lenz's Law

NASA Technical Reports Server (NTRS)

Lee, Russell

1999-01-01

Jupiter has a large, complex, and intense magnetic field that is thought to arise from electrical currents in the rapidly spinning metallic hydrogen interior. The strong magnetic field can induce currents when the conductive tether is directed toward or away from Jupiter. The currents can be stored and used for both propulsion and power generation. Therefore, our spacecraft might be able to visit several Jovian moons or maintain in the orbit around Jupiter. In our future space traveling, we also can use this technical skill to travel to other planets without any fuel. First-year physics textbooks describe Lenz's Law in which current is induced in a conductor moving through a stationary magnetic field. A demonstration of induced current in a stationary conductor and moving magnetic field is described, which may have space-tether application.

Family Portrait of Jupiter's Great Red Spot and the Galilean Satellites

NASA Technical Reports Server (NTRS)

1997-01-01

This 'family portrait,' a composite of the Jovian system, includes the edge of Jupiter with its Great Red Spot, and Jupiter's four largest moons, known as the Galilean satellites. From top to bottom, the moons shown are Io, Europa, Ganymede and Callisto.

The Great Red Spot, a storm in Jupiter's atmosphere, is at least 300 years old. Winds blow counterclockwise around the Great Red Spot at about 400 kilometers per hour (250 miles per hour). The storm is larger than one Earth diameter from north to south, and more than two Earth diameters from east to west. In this oblique view, the Great Red Spot appears longer in the north-south direction.

Europa, the smallest of the four moons, is about the size of Earth's moon, while Ganymede is the largest moon in the solar system. North is at the top of this composite picture in which the massive planet and its largest satellites have all been scaled to a common factor of 15 kilometers (9 miles) per picture element.

The Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft obtained the Jupiter, Io and Ganymede images in June 1996, while the Europa images were obtained in September 1996. Because Galileo focuses on high resolution imaging of regional areas on Callisto rather than global coverage, the portrait of Callisto is from the 1979 flyby of NASA's Voyager spacecraft.

Launched in October 1989, the spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at: http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at: http:/ /www.jpl.nasa.gov/galileo/sepo.

Strong tidal dissipation in Io and Jupiter from astrometric observations.

PubMed

Lainey, Valéry; Arlot, Jean-Eudes; Karatekin, Ozgür; Van Hoolst, Tim

2009-06-18

Io is the volcanically most active body in the Solar System and has a large surface heat flux. The geological activity is thought to be the result of tides raised by Jupiter, but it is not known whether the current tidal heat production is sufficiently high to generate the observed surface heat flow. Io's tidal heat comes from the orbital energy of the Io-Jupiter system (resulting in orbital acceleration), whereas dissipation of energy in Jupiter causes Io's orbital motion to decelerate. Here we report a determination of the tidal dissipation in Io and Jupiter through its effect on the orbital motions of the Galilean moons. Our results show that the rate of internal energy dissipation in Io (k(2)/Q = 0.015 +/- 0.003, where k(2) is the Love number and Q is the quality factor) is in good agreement with the observed surface heat flow, and suggest that Io is close to thermal equilibrium. Dissipation in Jupiter (k(2)/Q = (1.102 +/- 0.203) x 10(-5)) is close to the upper bound of its average value expected from the long-term evolution of the system, and dissipation in extrasolar planets may be higher than presently assumed. The measured secular accelerations indicate that Io is evolving inwards, towards Jupiter, and that the three innermost Galilean moons (Io, Europa and Ganymede) are evolving out of the exact Laplace resonance.

The Longevity of Water Ice on Ganymedes and Europas around Migrated Giant Planets

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

Lehmer, Owen R.; Catling, David C.; Zahnle, Kevin J., E-mail: olehmer@gmail.com

The gas giant planets in the Solar System have a retinue of icy moons, and we expect giant exoplanets to have similar satellite systems. If a Jupiter-like planet were to migrate toward its parent star the icy moons orbiting it would evaporate, creating atmospheres and possible habitable surface oceans. Here, we examine how long the surface ice and possible oceans would last before being hydrodynamically lost to space. The hydrodynamic loss rate from the moons is determined, in large part, by the stellar flux available for absorption, which increases as the giant planet and icy moons migrate closer to themore » star. At some planet–star distance the stellar flux incident on the icy moons becomes so great that they enter a runaway greenhouse state. This runaway greenhouse state rapidly transfers all available surface water to the atmosphere as vapor, where it is easily lost from the small moons. However, for icy moons of Ganymede’s size around a Sun-like star we found that surface water (either ice or liquid) can persist indefinitely outside the runaway greenhouse orbital distance. In contrast, the surface water on smaller moons of Europa’s size will only persist on timescales greater than 1 Gyr at distances ranging 1.49–0.74 au around a Sun-like star for Bond albedos of 0.2 and 0.8, where the lower albedo becomes relevant if ice melts. Consequently, small moons can lose their icy shells, which would create a torus of H atoms around their host planet that might be detectable in future observations.« less

Planetary Science Enabled by High Power Ion Propulsion Systems from NASA's Prometheus Program

NASA Astrophysics Data System (ADS)

Cooper, John

2004-11-01

NASA's Prometheus program seeks to develop new generations of spacecraft nuclear-power and ion propulsion systems for applications to future planetary missions. The Science Definition Team for the first mission in the Prometheus series, the Jupiter Icy Moons Orbiter (JIMO), has defined science objectives for in-situ orbital exploration of the icy Galilean moons (Europa, Ganymede, Callisto) and the Jovian magnetosphere along with remote observations of Jupiter's atmosphere and aurorae, the volcanic moon Io, and other elements of the Jovian system. Important to this forum is that JIMO power and propulsion systems will need to be designed to minimize magnetic, radio, neutral gas, and plasma backgrounds that might otherwise interfere with achievement of mission science objectives. Another potential Prometheus mission of high science interest would be an extended tour of primitive bodies in the solar system, including asteroids, Jupiter family comets, Centaurs, and Kuiper Belt Objects (KBO). The final landed phase of this mission might include an active keplerian experiment for detectable (via downlink radio doppler shift) acceleration of a small kilometer-size Centaur or KBO object, likely the satellite of a larger object observable from Earth. This would have obvious application to testing of mitigation techniques for Earth impact hazards.

Early development of Science Opportunity Analysis tools for the Jupiter Icy Moons Explorer (JUICE) mission

NASA Astrophysics Data System (ADS)

Cardesin Moinelo, Alejandro; Vallat, Claire; Altobelli, Nicolas; Frew, David; Llorente, Rosario; Costa, Marc; Almeida, Miguel; Witasse, Olivier

2016-10-01

JUICE is the first large mission in the framework of ESA's Cosmic Vision 2015-2025 program. JUICE will survey the Jovian system with a special focus on three of the Galilean Moons: Europa, Ganymede and Callisto.The mission has recently been adopted and big efforts are being made by the Science Operations Center (SOC) at the European Space and Astronomy Centre (ESAC) in Madrid for the development of tools to provide the necessary support to the Science Working Team (SWT) for science opportunity analysis and early assessment of science operation scenarios. This contribution will outline some of the tools being developed within ESA and in collaboration with the Navigation and Ancillary Information Facility (NAIF) at JPL.The Mission Analysis and Payload Planning Support (MAPPS) is developed by ESA and has been used by most of ESA's planetary missions to generate and validate science observation timelines for the simulation of payload and spacecraft operations. MAPPS has the capability to compute and display all the necessary geometrical information such as the distances, illumination angles and projected field-of-view of an imaging instrument on the surface of the given body and a preliminary setup is already in place for the early assessment of JUICE science operations.NAIF provides valuable SPICE support to the JUICE mission and several tools are being developed to compute and visualize science opportunities. In particular the WebGeoCalc and Cosmographia systems are provided by NAIF to compute time windows and create animations of the observation geometry available via traditional SPICE data files, such as planet orbits, spacecraft trajectory, spacecraft orientation, instrument field-of-view "cones" and instrument footprints. Other software tools are being developed by ESA and other collaborating partners to support the science opportunity analysis for all missions, like the SOLab (Science Operations Laboratory) or new interfaces for observation definitions and

Making Space Travel to Jupiter Possible

NASA Technical Reports Server (NTRS)

Barker, Samuel P.

2004-01-01

From man landing on the moon to a simple satellite being launched into orbit, many incredible space accomplishments have been witnessed by us all. However, what goes un-noticed to the common man is the extensive research and testing that lasts months, years, and even decades. Much of this required research just so happens to take place in the corridors of the Glen Research Center building number 49. In the Advanced Materials division of G.R.C., a number of researchers have the responsibility of discovering which metal, ceramic, or polymer is best for a specific application. Under the guidance of mentor extraordinaire Frank Ritzert, I am involved in many critical projects dealing with refractory metals, two of which I will mention in this report. The Jupiter Icy Moons Orbiter (JIMO) project actually was under full swing back in the 50's and early 60's. To enable the 14 year trek to the icy moons of Europa, Callisto, and Ganymede, nuclear propulsion methods were selected. Due to the extreme temperature of the reactor and the extended time period, a refractory metal would need to be implemented. After years of research and progress, the program was suddenly canceled. About a decade ago, the JIMO project was re-instated and now has a goal for departure around 2014. However, a few obstacles lie in our way concerning the use of refractory metals. In certain areas of the orbiter a joint is required between the refractories and other less dense metals. Two of these joints are with nickel based super alloys. Being an intern for Frank Ritzert, the refractory metals expert, I have the opportunity to develop the best method to braze refractory metals to Nickel 201. This involves the actual brazing, electron microscopy and reporting the results. My second project involves a certain part of the orbiter where Niobium 1Zirconium, a refractory metal, is joined with Hastelloy-X a Ni based metal. Small quantities of oxygen, helium and other impurities in the Ni alloy could diffuse

A Radiation-Hard Silicon Drift Detector Array for Extraterrestrial Element Mapping

NASA Technical Reports Server (NTRS)

Gaskin, Jessica; Chen, Wei; De Geronimo, Gianluigi; Keister, Jeff; Li, Shaouri; Li, Zhen; Siddons, David P.; Smith, Graham

2011-01-01

Measurement of x-rays from the surface of objects can tell us about the chemical composition Absorption of radiation causes characteristic fluorescence from material being irradiated. By measuring the spectrum of the radiation and identifying lines in the spectrum, the emitting element (s) can be identified. This technique works for any object that has no absorbing atmosphere and significant surface irradiation : Our Moon, the icy moons of Jupiter, the moons of Mars, the planet Mercury, Asteroids and Comets

Crater Relaxation and Stereo Imaging of the Icy Satellites of Jupiter and Saturn

NASA Astrophysics Data System (ADS)

Phillips, C. B.; Beyer, R. A.; Nimmo, F.; Roberts, J. H.; Robuchon, G.

2010-12-01

Crater relaxation has been used as a probe of subsurface temperature structure for over thirty years, both on terrestrial bodies and icy satellites. We are developing and testing two independent methods for processing stereo pairs to produce digital elevation models, to address how crater relaxation depends on crater diameter, geographic location, and stratigraphic position on the icy satellites of Jupiter and Saturn. Our topographic profiles will then serve as input into two numerical models, one viscous and one viscoelastic, to allow us to probe the subsurface thermal profiles and relaxation histories of these satellites. We are constructing stereo topography from Galileo and Cassini image pairs using the NASA Ames Stereo Pipeline (Moratto et al. 2010), an automated stereogrammetry tool designed for processing planetary imagery captured from orbiting and landed robotic explorers on other planets. We will also be using the commercial program SOCET SET from BAE Systems (Miller and Walker 1993; 1995). Qualitatively, it is clear that there are large spatial variations in the degree of crater relaxation among Jupiter’s and Saturn’s satellites. However, our use of stereo topography will allow quantitative measures of crater relaxation (e.g. depth:diameter ratio or equivalent) to be derived. Such measures are essential to derive quantitative estimates of the heat fluxes responsible for this relaxation. Estimating how surface heat flux has varied with time provides critical constraints on satellite thermal (and orbital) evolution. Craters undergo viscous relaxation over time at a rate that depends on the temperature gradient and crater scale. We are investigating how the near-surface satellite heat flux varied in time and space, based on our crater relaxation observations. Once we have crater profiles from our DEMs, we use them as input to two theoretical approaches: a relatively simple (viscous) numerical model in which time-varying heat fluxes can be included, and

Virtual Jupiter - Real Learning

NASA Astrophysics Data System (ADS)

Ruzhitskaya, Lanika; Speck, A.; Laffey, J.

2010-01-01

How many earthlings went to visit Jupiter? None. How many students visited virtual Jupiter to fulfill their introductory astronomy courses’ requirements? Within next six months over 100 students from University of Missouri will get a chance to explore the planet and its Galilean Moons using a 3D virtual environment created especially for them to learn Kepler's and Newton's laws, eclipses, parallax, and other concepts in astronomy. The virtual world of Jupiter system is a unique 3D environment that allows students to learn course material - physical laws and concepts in astronomy - while engaging them into exploration of the Jupiter's system, encouraging their imagination, curiosity, and motivation. The virtual learning environment let students to work individually or collaborate with their teammates. The 3D world is also a great opportunity for research in astronomy education to investigate impact of social interaction, gaming features, and use of manipulatives offered by a learning tool on students’ motivation and learning outcomes. Use of 3D environment is also a valuable source for exploration of how the learners’ spatial awareness can be enhanced by working in 3-dimensional environment.

Radar-Sounding of Icy Mantles and Comets Using Natural Radio Noise

NASA Astrophysics Data System (ADS)

Winebrenner, D. P.; Sahr, J. D.

2011-10-01

Radar-sounding of ice sheets on Earth yields crucial information on ice history and dynamics, including discoveries of subglacial lakes beneath 3-4 km of ice [1]. Mars Express and the Mars Reconnaissance Orbiter (MRO) have now demonstrated the corresponding power of orbital radar sounding for planetary exploration, in particular by imaging structures within and beneath kilometers of Martian water ice [2-4]. Based on this experience, a sophisticated orbital radar sounder is planned for a flagship mission to Europa, with the aim of imaging stratigraphy, faults, diapirs and other geological structure in the upper few kilometers of the water-ice mantle there, and possibly even detecting the upper surface of the (likely) underlying ocean [5]. Recent modeling of the formation and evolution of volatilerich bodies suggests that oceans or lakes of liquid water occur beneath water-ice mantles in a surprising variety of places, including Ceres in the outer asteroid belt [6], 3 of the 4 Galilean moons of Jupiter as well as Enceladus and Titan in the Saturnian system [7], and possibly even Pluto [8]. Thus there is now a wide scope for low-cost missions to bodies of exceptional interest, and for radar sounding of icy mantles to image near-surface structural geology related to underlying water (whether past or present).

High pressure ices are not the end of the story for large icy moons habitability: experimental studies of salts effects on high pressure ices and the implications for icy worlds large hydrosphere structure and chemical evolution

NASA Astrophysics Data System (ADS)

Journaux, Baptiste; Abramson, Evan; Brown, J. Michael; Bollengier, Olivier

2017-10-01

The presence of several phases of deep high-pressure ices in large icy moons hydrosphere has often been pointed as a major limitation for the habitability of an uppermost ocean. As they are gravitationally stable bellow liquid H2O, they are thought to act as a chemical barrier between the rocky bed and the ocean. Solutes, including salt species such as NaCl and MgSO4, have been suggested inside icy world oceans from remote sensing, magnetic field measurements and chondritic material alteration models. Unfortunately, the pressures and temperatures inside these hydrospheres are very different from the one found in Earth aqueous environments, so most of our current thermodynamic databases do not cover the range of conditions relevant for modeling realistically large icy worlds interiors.Recent experimental results have shown that the presence of solutes, and more particularly salts, in equilibrium with high pressure ices have large effects on the stability, buoyancy and chemistry of all the phases present at these extreme conditions.In particular brines have been measured to be sometimes more dense than the high pressure ices at melting conditions, possibly creating several oceanic layer "sandwiched" in between two ices shells or in contact with the rocky bed.Other effects currently being investigated by our research group also covers ice melting curve depressions that depend on the salt species and incorporation of solutes inside the crystallographic lattice of high pressure ices. Both of these could have very important implication at the planetary scale, enabling thicker/deeper liquid oceans, and allowing chemical transportation through the high pressure ice layer in large icy worlds.We will present the latest results obtained in-situ using diamond anvil cell high pressure allowing to probe the density, chemistry and thermodynamic properties of high pressure ice and aqueous solutions in equilibrium with Na-Mg-SO4-Cl ionic species.We will also discuss the new

The interaction between Saturn's moons and their plasma environments

NASA Astrophysics Data System (ADS)

Simon, Sven; Roussos, Elias; Paty, Carol S.

2015-11-01

Since the arrival of the Cassini spacecraft at Saturn in July 2004, newly collected plasma and magnetic field data have greatly expanded our knowledge on the interaction between the giant planet's multifaceted family of moons and its magnetospheric environment. Cassini has already accomplished more than 200 orbits around Saturn, encompassing 111 flybys of the giant planet's largest moon Titan and 20 encounters of Enceladus. This small icy moon had been identified as the major source of magnetospheric plasma and neutral particles during the first year of Cassini's tour in the Saturnian system. In addition, the spacecraft has paid visits to several other icy satellites in the inner and middle magnetosphere: Rhea, Dione and Tethys. Depending on the ambient magnetospheric flow parameters as well as the properties of its atmosphere/ionosphere and surface, each of these moons generates a characteristic and unique set of perturbation signatures in the magnetospheric plasma incident upon it. Therefore, observations made during close flybys of Saturn's moons by the Cassini plasma and magnetic field detectors contain valuable diagnostic information on the properties of the moons' atmospheres, surfaces and even their interiors. However, the spacecraft can measure these plasma and magnetic field perturbations only along its trajectory, whereas the interaction between the moons and their plasma environments constitutes a complex three-dimensional process. Therefore, sophisticated models are required in order to place the data collected along Cassini's flyby trajectories within the context of the full three-dimensional moon-plasma interaction scenarios. In this review, we combine observations from the Cassini mission with sophisticated modeling results to draw a comprehensive picture of the interaction between Saturn's largest moons and their highly dynamic plasma environments.

Dielectric properties of Jovian satellite ice analogs for subsurface radar exploration: A review

NASA Astrophysics Data System (ADS)

Pettinelli, Elena; Cosciotti, Barbara; Di Paolo, Federico; Lauro, Sebastian Emanuel; Mattei, Elisabetta; Orosei, Roberto; Vannaroni, Giuliano

2015-09-01

The first European mission dedicated to the exploration of Jupiter and its icy moons (JUpiter ICy moons Explorer—JUICE) will be launched in 2022 and will reach its final destination in 2030. The main goals of this mission are to understand the internal structure of the icy crusts of three Galilean satellites (Europa, Ganymede, and Callisto) and, ultimately, to detect Europa's subsurface ocean, which is believed to be the closest to the surface among those hypothesized to exist on these moons. JUICE will be equipped with the 9 MHz subsurface-penetrating radar RIME (Radar for Icy Moon Exploration), which is designed to image the ice down to a depth of 9 km. Moreover, a parallel mission to Europa, which will host onboard REASON (Radar for Europa Assessment and Sounding: Ocean to Near-surface) equipped with 9MHz and 60MHz antennas, has been recently approved by NASA. The success of these experiments strongly relies on the accurate prediction of the radar performance and on the optimal processing and interpretation of radar echoes that, in turn, depend on the dielectric properties of the materials composing the icy satellite crusts. In the present review we report a complete range of potential ice types that may occur on these icy satellites to understand how they may affect the results of the proposed missions. First, we discuss the experimental results on pure and doped water ice in the framework of the Jaccard theory, highlighting the critical aspects in terms of a lack of standard laboratory procedures and inconsistency in data interpretation. We then describe the dielectric behavior of extraterrestrial ice analogs like hydrates and icy mixtures, carbon dioxide ice and ammonia ice. Building on this review, we have selected the most suitable data to compute dielectric attenuation, velocity, vertical resolution, and reflection coefficients for such icy moon environments, with the final goal being to estimate the potential capabilities of the radar missions as a

Between ice and gas: CO2 on the icy satellites of Jupiter and Saturn

NASA Astrophysics Data System (ADS)

Hibbitts, C.

2010-12-01

CO2 exists in the surfaces of the icy Galilean and Saturnian satellites [1-6], yet despite its discovery over a decade ago on Ganymede, and five years ago on the Saturnian satellites, its nature is still debated [7]. On the Galilean satellites Callisto and Ganymede, the CO2 that is detected is bound to, or trapped within, the non-ice materials that prevent it from sublimating or otherwise escaping from the surface. On Europa, it resides within both the ice and nonice materials [8,9]. While greater abundances of CO2 may exist in the interiors of these moons, or small amounts may be continually created through particle bombardment of the surface, the observed CO2 is only a trace material, with a few hundred molecules responsible for the deepest absorption features and an estimated molar abundance of 0.1% [2; 10-12]. Yet its presence may provide essential clues to processes that shape the surfaces of the moon [13] and potentially key to understanding the composition of potential oceans in the subsurfaces. We continue measurements of the infrared properties associated with CO2 adsorbed onto nonice materials under pressures and at temperatures relevant to these icy satellites using bidirectional reflectance spectroscopy from ~ 1.5 to 5.5 μm. Previous measurements, using transmission spectroscopy, demonstrated both a compositional and a temperature dependence on the spectral signature of adsorbed CO2 [14]. Bidirectional spectroscopy enables detection of lower concentrations of adsorbate on fine-grained materials such as clays due to their large surface area to volume ratios and thus large surface areas that may be covered by adsorbate [15]. The effectiveness of transmission spectroscopy was also limited by the strong absorption of light within the pressed sample and its impermeability, which limited the coverage by adsorbate to the pellet’s outer surface. All measurements demonstrate that CO2 adsorbs onto montmorillonite clays, possibly due to its quadrupole moment

Space Radiation Effects and Reliability Consideration for the Proposed Jupiter Europa Orbiter

NASA Technical Reports Server (NTRS)

Johnston, Allan

2011-01-01

The proposed Jupiter Europa Orbiter (JEO) mission to explore the Jovian moon Europa poses a number of challenges. The spacecraft must operate for about seven years during the transit time to the vicinity of Jupiter, and then endure unusually high radiation levels during exploration and orbiting phases. The ability to withstand usually high total dose levels is critical for the mission, along with meeting the high reliability standards for flagship NASA missions. Reliability of new microelectronic components must be sufficiently understood to meet overall mission requirements.The proposed Jupiter Europa Orbiter (JEO) mission to explore the Jovian moon Europa poses a number of challenges. The spacecraft must operate for about seven years during the transit time to the vicinity of Jupiter, and then endure unusually high radiation levels during exploration and orbiting phases. The ability to withstand usually high total dose levels is critical for the mission, along with meeting the high reliability standards for flagship NASA missions. Reliability of new microelectronic components must be sufficiently understood to meet overall mission requirements.

JunoCam's Images of Jupiter

NASA Astrophysics Data System (ADS)

Hansen, C. J.; Ravine, M. A.; Caplinger, M. A.; Orton, G. S.; Ingersoll, A. P.; Jensen, E.; Lipkaman, L.; Krysak, D.; Zimdar, R.; Bolton, S. J.

2016-12-01

JunoCam is a visible imager on the Juno spacecraft in orbit around Jupiter. It is a wide angle camera (58 deg field of view) with 4 color filters: red, green and blue (RGB) and methane at 889 nm, designed for optimal imaging of Jupiter's poles. Juno's elliptical polar orbit will offer unique views of Jupiter's polar regions with a spatial scale of 50 km/pixel. At closest approach the images will have a spatial scale of 3 km/pixel. As a push-frame imager on a rotating spacecraft, JunoCam uses time-delayed integration to take advantage of the spacecraft spin to extend integration time to increase signal. Images of Jupiter's poles reveal a largely uncharted region of Jupiter, as nearly all earlier spacecraft have orbited or flown by in the equatorial plane. Most of the images of Jupiter will be acquired in the +/-2 hours surrounding closest approach. The polar vortex, polar cloud morphology, and winds will be investigated. RGB color images of the aurora will be acquired if detectable. Stereo images and images taken with the methane filter will allow us to estimate cloud-top heights. Images of the cloud-tops will aid in understanding the data collected by other instruments on Juno that probe deeper in the atmosphere. During the two months that Jupiter is too close to the sun for ground-based observers to collect data, JunoCam will take images routinely to monitor large-scale features. Occasional, opportunistic images of the Galilean moons will be acquired.

Study of Geological Analogues for Understanding the Radar Sounder Response of the RIME Targets

NASA Astrophysics Data System (ADS)

Thakur, S.; Bruzzone, L.

2017-12-01

Radar for Icy Moon Exploration (RIME), the radar sounder onboard the Jupiter Icy Moons Explorer (JUICE), is aimed at characterizing the ice shells of the Jovian moons - Ganymede, Europa and Callisto. RIME is optimized to operate at 9 MHz central frequency with bandwidth of 1 MHz and 2.7 MHz to achieve a penetration depth up to 9 km through ice. We have developed an approach to the definition of a database of simulated RIME radargrams by leveraging the data available from airborne and orbital radar sounder acquisitions over geological analogues of the expected icy moon features. These simulated radargrams are obtained by merging real radar sounder data with models of the subsurface of the Jupiter icy moons. They will be useful for geological interpretation of the RIME radargrams and for better predicting the performance of RIME. The database will also be useful in developing pre-processing and automatic feature extraction algorithms to support data analysis during the mission phase of RIME. Prior to the JUICE mission exploring the Jovian satellites with RIME, there exist radar sounders such as SHARAD (onboard MRO) and MARSIS (onboard MEX) probing Mars, the LRS (onboard SELENE) probing the Moon, and many airborne sounders probing the polar regions of Earth. Analogues have been identified in these places based on similarity in geo-morphological expression. Moreover, other analogues have been identified on the Earth for possible dedicated acquisition campaigns before the RIME operations. By assuming that the subsurface structure of the RIME targets is approximately represented in the analogue radargrams, the difference in composition is accounted for by imposing different dielectric and subsurface attenuation models. The RIME radargrams are simulated from the analogue radargrams using the radar equation and the RIME processing chain and accounting for different possible scenarios in terms of subsurface structure, dielectric properties and instrument parameters. For

Jupiter - Solid or Gaseous? Ask Juno

NASA Astrophysics Data System (ADS)

Ackerman, J. A., Jr.

2015-12-01

Data from Cassini, Galileo, S-L 9 and Ulysses suggest Jupiter and Saturn are solid, frozen, Methane Gas Hydrate (MGH) planets. The bulk of these giants formed slow and cold by the natural accretion of snowflakes at their current orbital radii in the presence of methane, forming rigid incompressible bodies. MGH, (CH4)8(H2O)46 (d=0.9), is consistent with the abundances of the elements comprising the Earth (H>O>C). Their combined MGH comprises >250 earth-masses of H2O. Jupiter (d=1.33) incorporated most of the heavy elements in the nascent solar system, exemplified by an enormously enhanced D/H. The temperature excess of Jupiter's atmosphere is the result of an impact ~6,000 years BP, triggering an incredibly energetic fusion explosion which ejected the masses of the proto-Galilean moons. It also initiated a continuing fusion furnace in the crater producing a jet of hot gases extending >2x106 km, beyond Callisto. The jet has slowly diminished over 6,000 years, resulting in the differences in the four Galilean Moons. The mass ejection (ang. mom.) slowed Jupiter's rotation until ~1930, currently interpreted as a drift of the Great Red Spot. A diminishing fusion reaction (D + p → 3He + γ) continues to this day, producing Jupiter's atmospheric 'temperature excess'. Jupiter's rapid rotation deflects the rising vortex of hot gases from the fusion reaction horizontally, driving multiple zonal vortices, constrained by the frozen MGH surface <1000 km below the cloud tops. It appears as the tilted Great Red Spot (GRS), ~30,000 km to the west of the crater at 22 o S Lat., which has remained unchanged in the last 350 years - impossible due to the enormous Coliolis effect. Streams of 3He produced in the fusion reaction exiting Jupiter through the center of the GRS have been detected by the Galileo probe and orbiter, Ulysses, and Cassini. The fusion releases methane, also heavy elements which oxidize as they rise, producing the cloud-top colors. The MGH hypothesis explains the

Europa and Callisto under the Watchful Gaze of Jupiter

NASA Image and Video Library

2000-12-21

One moment in an ancient, orbital dance is caught in this color picture taken by NASA Cassini spacecraft on Dec. 7, 2000, just as two of Jupiter four major moons, Europa and Callisto, were nearly perfectly aligned with each other.

Cold cases: What we don't know about Saturn's Moons

NASA Astrophysics Data System (ADS)

Buratti, B. J.; Clark, R. N.; Crary, F.; Hansen, C. J.; Hendrix, A. R.; Howett, C. J. A.; Lunine, J.; Paranicas, C.

2018-06-01

The Cassini-Huygens mission turned the moons of Saturn into tangible worlds. Although the discoveries from the spacecraft have been compiled in various review articles (e. g., Dougherty et al., 2009), there is no single publication that summarizes the remaining outstanding questions. Drawing on a workshop sponsored by the Cassini Project, we summarize the unanswered questions for the main icy moons of Saturn - Mimas, Enceladus, Tethys, Dione, Rhea, Hyperion, Iapetus, and Phoebe - for the disciplines of surface composition, geology, thermal properties, Enceladus's plume activity, interiors, and the interactions between Saturn's magnetosphere and the moons.

Soft X-Ray Emissions from Planets and Moons

NASA Technical Reports Server (NTRS)

Bhardwaj, A.; Gladstone, G. R.; Elsner, R. F.; Waite, J. H., Jr.; Grodent, D.; Lewis, W. S.; Crary, F. J.; Weisskopf, M. C.; Howell, R. R.; Johnson, R. E.;

The Jovian Electron and Ion Spectrometer (JEI) for the JUICE mission

NASA Astrophysics Data System (ADS)

Fränz, M.; Bührke, U.; Ferreira, P.; Fischer, H.; Heumüller, P.; Krupp, N.; Kühne, W.; Roussos, E.

2017-09-01

The magnetosphere of Jupiter is apart from the Sun the strongest source of charged particles in the Solar system. The interaction of these particles with the exospheres of the Jovian moons forms one of the most complex plasma laboratories encountered by human space flight. For this reason the plasma analyzer package forms a crucial experiment of the Jupiter Icy Moon Explorer (JUICE). As part of the Plasma Environment Package (PEP) we here describe a combined electron and ion spectrometer which is able to measure the electron and ion distribution functions in the energy range 1 to 50000 eV with high sensitivity and time resolution. This instrument is called the Jovian Electron and Ion Analyzer, JEI.

Massive Gas Cloud Around Jupiter

NASA Technical Reports Server (NTRS)

2003-01-01

An innovative instrument on NASA's Cassini spacecraft makes the space environment around Jupiter visible, revealing a donut-shaped gas cloud encircling the planet.

The image was taken with the energetic neutral atom imaging technique by the Magnetospheric Imaging Instrument on Cassini as the spacecraft flew past Jupiter in early 2001 at a distance of about 10 million kilometers (6 million miles). This technique provides information about a source by detecting neutral atoms emitted by the source, comparable to how a camera reveals information about an object by detecting photons coming from the object.

The central object in this image represents energetic neutral atom emissions from Jupiter itself. The outer two objects represent emissions from a donut-shaped cloud, or torus, that shares an orbit with Jupiter's moon Europa. The cloud's emissions appear dot-like because of the viewing angle. The torus is viewed edge-on, and the image is brightest at the line-of-sight angles that pass through the greatest volume of it.

Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages Cassini for NASA's Office of Space Science, Washington, D.C.

Jupiter Formation, Life in the Slow Lane?

NASA Astrophysics Data System (ADS)

Hamilton, D. P.; Kortenkamp, S. J.; Fleming, H. J.

2000-10-01

The growth of Jupiter, as predicted by the favored core-accretion model of planetary formation, is a two-stage process. First an ≈ 10 Earth mass core is formed by runaway growth of an icy protoplanet, after which the protoplanet gravitationally captures over 300 Earth masses of gas directly from the Solar Nebula. The process is thought to take ≈ 107 years. An alternate possibility, the mass-instability hypothesis, has recently experienced a resurgence of interest due to the increasingly rapid discoveries of unusual jovian-mass extrasolar planets. A sufficiently massive gas disk can become unstable and form an azimuthally asymmetric blob destined to become a giant planet in as short as 102 years. Which process actually formed Jupiter? Trojan asteroids, very numerous and with close dynamical links to Jupiter, are ideally suited to provide critical clues about Jupiter's formation. A number of processes could potentially capture objects into 1:1 resonance with Jupiter including radial migration, gas drag, mass accretion, collisional emplacement, disk tides, and gravitational scattering by massive protoplanetary embryos. We are currently undertaking a systematic study of each of these processes. The mass-instability scenario, in its simplest form, posits a fully-formed Jupiter with L4 and L5 points clear of gas and unpopulated with Trojans. By contrast, in the core-accretion model, precursor material is already trapped in 1:1 resonance with the jovian core. Furthermore, subsequent mass accretion and gas drag systematically concentrate matter toward the L4 and L5 points. The emerging theme is that a populous Trojan region is more easily achieved by the slower core-accretion model.

The Impact History Of The Moon

NASA Technical Reports Server (NTRS)

Cohen, B. A.

2010-01-01

The bombardment history of the Earth-Moon system has been debated since the first recognition that the circular features on the Moon may be impact craters. Because the lunar impact record is the only planetary impact record to be calibrated with absolute ages, it underpins our understanding of geologic ages on every other terrestrial planet. One of the more remarkable results to come out of lunar sample analyses is the hypothesis that a large number of impact events occurred on the Moon during a narrow window in time approximately 3.8 to 4.1 billion years ago (the lunar cataclysm ). Subsequent work on the lunar and martian meteorite suites; remote sensing of the Moon, Mars, asteroids, and icy satellites; improved dynamical modeling; and investigation of terrestrial zircons extend the cataclysm hypothesis to the Earth, other terrestrial planets, and possibly the entire solar system. Renewed US and international interest in exploring the Moon offers new potential to constrain the Earth-Moon bombardment history. This paper will review the lunar bombardment record, timing and mechanisms for cataclysmic bombardment, and questions that may be answered in a new age of exploration.

Distant Moons

NASA Image and Video Library

2016-08-15

Saturn's moons Tethys and Hyperion appear to be near neighbors in this Cassini view, even though they are actually 930,000 miles (1.5 million kilometers) apart here. Tethys is the larger body on the left. These two icy moons of Saturn are very different worlds. To learn more about Hyperion (170 miles or 270 kilometers across). This view looks toward the trailing side of Tethys. North on Tethys is up and rotated 1 degree to the left. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Aug. 15, 2015. The view was acquired at a distance of approximately 750,000 miles (1.2 million kilometers) from Tethys. Image scale is 4.4 miles (7.0 kilometers) per pixel. The distance to Hyperion was 1.7 million miles (2.7 million kilometers) with an image scale of 10 mile (16 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA20493

Jupiter-Io Montage

NASA Technical Reports Server (NTRS)

2007-01-01

This is a montage of New Horizons images of Jupiter and its volcanic moon Io, taken during the spacecraft's Jupiter flyby in early 2007. The Jupiter image is an infrared color composite taken by the spacecraft's near-infrared imaging spectrometer, the Linear Etalon Imaging Spectral Array (LEISA) at 1:40 UT on Feb. 28, 2007. The infrared wavelengths used (red: 1.59 um, green: 1.94 um, blue: 1.85 um) highlight variations in the altitude of the Jovian cloud tops, with blue denoting high-altitude clouds and hazes, and red indicating deeper clouds. The prominent bluish-white oval is the Great Red Spot. The observation was made at a solar phase angle of 75 degrees but has been projected onto a crescent to remove distortion caused by Jupiter's rotation during the scan. The Io image, taken at 00:25 UT on March 1st 2007, is an approximately true-color composite taken by the panchromatic Long-Range Reconnaissance Imager (LORRI), with color information provided by the 0.5 um ('blue') and 0.9 um ('methane') channels of the Multispectral Visible Imaging Camera (MVIC). The image shows a major eruption in progress on Io's night side, at the northern volcano Tvashtar. Incandescent lava glows red beneath a 330-kilometer high volcanic plume, whose uppermost portions are illuminated by sunlight. The plume appears blue due to scattering of light by small particles in the plume

This montage appears on the cover of the Oct. 12, 2007, issue of Science magazine.

Radio Sounding Science at High Powers

NASA Technical Reports Server (NTRS)

Green, J. L.; Reinisch, B. W.; Song, P.; Fung, S. F.; Benson, R. F.; Taylor, W. W. L.; Cooper, J. F.; Garcia, L.; Markus, T.; Gallagher, D. L.

2004-01-01

Future space missions like the Jupiter Icy Moons Orbiter (JIMO) planned to orbit Callisto, Ganymede, and Europa can fully utilize a variable power radio sounder instrument. Radio sounding at 1 kHz to 10 MHz at medium power levels (10 W to kW) will provide long-range magnetospheric sounding (several Jovian radii) like those first pioneered by the radio plasma imager instrument on IMAGE at low power (less than l0 W) and much shorter distances (less than 5 R(sub E)). A radio sounder orbiting a Jovian icy moon would be able to globally measure time-variable electron densities in the moon ionosphere and the local magnetospheric environment. Near-spacecraft resonance and guided echoes respectively allow measurements of local field magnitude and local field line geometry, perturbed both by direct magnetospheric interactions and by induced components from subsurface oceans. JIMO would allow radio sounding transmissions at much higher powers (approx. 10 kW) making subsurface sounding of the Jovian icy moons possible at frequencies above the ionosphere peak plasma frequency. Subsurface variations in dielectric properties, can be probed for detection of dense and solid-liquid phase boundaries associated with oceans and related structures in overlying ice crusts.

Experiences in managing the Prometheus Project

NASA Technical Reports Server (NTRS)

Lehman, David H.; Clark, Karla B.; Cook, Beverly A.; Gavit, Sarah A.; Kayali, Sammy A.; McKinney, John C.; Milkovich, David C.; Reh, Kim R.; Taylor, Randall L.; Casani, John R.

2006-01-01

Congress authorized NASA?s Prometheus Project in February 2003, with the first Prometheus mission slated to explore the icy moons of Jupiter. The Project had two major objectives: (1) to develop a nuclear reactor that would provide unprecedented levels of power and show that it could be processed safely and operated reliably in space for long-duration, deep-space exploration and (2) to explore the three icy moons of Jupiter - Callisto, Ganymede, and Europa - and return science data that would meet the scientific goals as set forth in the Decadal Survey Report of the National Academy of Sciences. Early in Project planning, it was determined that the development of the Prometheus nuclear powered Spaceship would be complex and require the intellectual knowledge residing at numerous organizations across the country. In addition, because of the complex nature of the Project and the multiple partners, approaches beyond those successfully used to manage a typical JPL project would be needed. This paper1 will describe the key experiences in managing Prometheus that should prove useful for future projects of similar scope and magnitude

Impact of comet Shoemaker-Levy 9 on Jupiter

NASA Technical Reports Server (NTRS)

Takata, Toshiko; Ahrens, Thomas J.; Okeefe, John D.; Orton, Glenn S.

1994-01-01

We have employed three-dimensional numerical simulations of the impact of Comet Shoemaker-Levy 9 (SL9) on Jupiter and the resulting vapor plume expansion using the smoothed particle hydrodynamics (SPH) method. An icy body with a diameter of 2 km can penetrate to an altitude of -350 km (0 km = 1 bar) and most of the incident kinetic energy is transferred to the atmosphere between -100 to -250 km. This energy is converted to potential energy of the resulting gas plume. The unconfined plume expands vertically and has a peak radiative power approximately equal to the total radiation from Jupiter's disc. The plume rises a few tens of atmospheric scale heights in approximately 10(exp 2) seconds. The rising plume reaches the altitude of approximately 3000 km; however, no atmospheric gas is accelerated to the escape velocity (approximately 60 km/s).

Impact on comet Shoemaker-Levy 9 on Jupiter

NASA Technical Reports Server (NTRS)

Ahrens, Thomas J.; Takata, Toshiko; O'Keefe, John D.; Orton, Glenn S.

1994-01-01

Three-dimensional numerical simulations of the impact of Comet Shoemaker - Levy 9 on Jupiter and the resulting vapor plume expansion were conducted using the Smoothed Particle Hydrodynamics (SPH) method. An icy body with a diameter of 2 km can penetrate to an altitude of -350 km (0 km = 1 bar) and most of the incident kinetic energy is transferred to the atmosphere between -100 km to -250 km. This energy is converted to potential energy of the resulting gas plume. The unconfined plume expands vertically and has a peak radiative power approximately equal to the total radiation from Jupiter's disk. The plume rises a few tens of atmospheric scale heights in approximately 10(exp 2) seconds. The rising plume reaches the altitude of approximately 3000 km, but no atmospheric gas is accelerated to the escape velocity (approximately 60 km/s).

Vital Signs: Seismology of Icy Ocean Worlds

NASA Astrophysics Data System (ADS)

Vance, Steven D.; Kedar, Sharon; Panning, Mark P.; Stähler, Simon C.; Bills, Bruce G.; Lorenz, Ralph D.; Huang, Hsin-Hua; Pike, W. T.; Castillo, Julie C.; Lognonné, Philippe; Tsai, Victor C.; Rhoden, Alyssa R.

2018-01-01

Ice-covered ocean worlds possess diverse energy sources and associated mechanisms that are capable of driving significant seismic activity, but to date no measurements of their seismic activity have been obtained. Such investigations could reveal the transport properties and radial structures, with possibilities for locating and characterizing trapped liquids that may host life and yielding critical constraints on redox fluxes and thus on habitability. Modeling efforts have examined seismic sources from tectonic fracturing and impacts. Here, we describe other possible seismic sources, their associations with science questions constraining habitability, and the feasibility of implementing such investigations. We argue, by analogy with the Moon, that detectable seismic activity should occur frequently on tidally flexed ocean worlds. Their ices fracture more easily than rocks and dissipate more tidal energy than the <1 GW of the Moon and Mars. Icy ocean worlds also should create less thermal noise due to their greater distance and consequently smaller diurnal temperature variations. They also lack substantial atmospheres (except in the case of Titan) that would create additional noise. Thus, seismic experiments could be less complex and less susceptible to noise than prior or planned planetary seismology investigations of the Moon or Mars.

Global Moon Coverage via Hyperbolic Flybys

NASA Technical Reports Server (NTRS)

Buffington, Brent; Strange, Nathan; Campagnola, Stefano

2012-01-01

The scientific desire for global coverage of moons such as Jupiter's Galilean moons or Saturn's Titan has invariably led to the design of orbiter missions. These orbiter missions require a large amount of propellant needed to insert into orbit around such small bodies, and for a given launch vehicle, the additional propellant mass takes away from mass that could otherwise be used for scientific instrumentation on a multiple flyby-only mission. This paper will present methods--expanding upon techniques developed for the design of the Cassini prime and extended missions--to obtain near global moon coverage through multiple flybys. Furthermore we will show with proper instrument suite selection, a flyby-only mission can provide science return similar (and in some cases greater) to that of an orbiter mission.

Juno Captures Jupiter Glow in Infrared Light

NASA Image and Video Library

2016-09-02

As NASA's Juno spacecraft approached Jupiter on Aug. 27, 2016, the Jovian Infrared Auroral Mapper (JIRAM) instrument captured the planet's glow in infrared light. The video is composed of 580 images collected over a period of about nine hours while Jupiter completed nearly a full rotation on its axis. The video shows the two parts composing the JIRAM imager: the lower one, in a red color scale, is used for mapping the planet's thermal emission at wavelengths around 4.8 microns; the upper one, in a blue color scale, is used to map the auroras at wavelengths around 3.45 microns. In this case the exposure time of the imager was optimized to observe the planet's thermal emission. However, it is possible to see a faint aurora and Jupiter's moon Io approaching the planet. The Great Red Spot is also visible just south of the planet's equator. A movie is available at http://photojournal.jpl.nasa.gov/catalog/PIA21036

Jupiter

NASA Astrophysics Data System (ADS)

Bagenal, Fran; Dowling, Timothy E.; McKinnon, William B.

2007-03-01

Preface; 1. Introduction F. Bagenal, T. E. Dowling and W. B. McKinnon; 2. The origin of Jupiter J. I. Lunine, A. Corandini, D. Gautier, T. C. Owen and G. Wuchterl; 3. The interior of Jupiter T. Guillot, D. J. Stevenson, W. B. Hubbard and D. Saumon; 4. The composition of the atmosphere of Jupiter F. W. Taylor, S. K. Atreya, Th. Encrenaz, D. M. Hunten, P. G. J. Irwin and T. C. Owen; 5. Jovian clouds and haze R. A. West, K. H. Baines, A. J. Friedson, D. Banfield, B. Ragent and F. W. Taylor; 6. Dynamics of Jupiter's atmosphere A. P. Ingersoll, T. E. Dowling, P. J. Gierasch, G. S. Orton, P. L. Read, A. Sánchez-Lavega, A. P. Showman, A. A. Simon-Miller and A. R. Vasavada; 7. The stratosphere of Jupiter J. I. Moses, T. Fouchet, R. V. Yelle, A. J. Friedson, G. S. Orton, B. Bézard, P. Drossart, G. R. Gladstone, T. Kostiuk and T. A. Livengood; 8. Lessons from Shoemaker-Levy 9 about Jupiter and planetary impacts J. Harrington, I. de Pater, S. H. Brecht, D. Deming, V. Meadows, K. Zahnle and P. D. Nicholson; 9. Jupiter's thermosphere and ionosphere R. V. Yelle and S. Miller; 10. Jovian dust: streams, clouds and rings H. Krüger, M. Horányi, A. V. Krivov and A. L. Graps; 11. Jupiter's ring-moon system J. A. Burns, D. P. Simonelli, M. R. Showalter, D. P. Hamilton, C. C. Porco, H. Throop and L. W. Esposito; 12. Jupiter's outer satellites and trojans D. C. Jewitt, S. Sheppard and C. Porco; 13. Interior composition, structure and dynamics of the Galilean satellites G. Schubert, J. D. Anderson, T. Spohn and W. B. McKinnon; 14. The lithosphere and surface of Io A. S. McEwen, L. P. Keszthelyi, R. Lopes, P. M. Schenk and J. R. Spencer; 15. Geology of Europa R. Greeley, C. F. Chyba, J. W. Head III, T. B. McCord, W. B. McKinnon, R. T. Pappalardo and P. Figueredo; 16. Geology of Ganymede R. T. Pappalardo, G. C. Collins, J. W. Head III, P. Helfenstein, T. B. McCord, J. M. Moore, L. M. Procktor, P. M. Shenk and J. R. Spencer; 17. Callisto J. M. Moore, C. R. Chapman. E. B. Bierhaus, R

Europa Planetary Protection for Juno Jupiter Orbiter

NASA Technical Reports Server (NTRS)

Bernard, Douglas E.; Abelson, Robert D.; Johannesen, Jennie R.; Lam, Try; McAlpine, William J.; Newlin, Laura E.

2010-01-01

NASA's Juno mission launched in 2011 and will explore the Jupiter system starting in 2016. Juno's suite of instruments is designed to investigate the atmosphere, gravitational fields, magnetic fields, and auroral regions. Its low perijove polar orbit will allow it to explore portions of the Jovian environment never before visited. While the Juno mission is not orbiting or flying close to Europa or the other Galilean satellites, planetary protection requirements for avoiding the contamination of Europa have been taken into account in the Juno mission design.The science mission is designed to conclude with a deorbit burn that disposes of the spacecraft in Jupiter's atmosphere. Compliance with planetary protection requirements is verified through a set of analyses including analysis of initial bioburden, analysis of the effect of bioburden reduction due to the space and Jovian radiation environments, probabilistic risk assessment of successful deorbit, Monte-Carlo orbit propagation, and bioburden reduction in the event of impact with an icy body.

Crescent Earth and Moon

NASA Technical Reports Server (NTRS)

1977-01-01

This picture of a crescent-shaped Earth and Moon -- the first of its kind ever taken by a spacecraft -- was recorded Sept. 18, 1977, by NASA's Voyager 1 when it was 7.25 million miles (11.66 million kilometers) from Earth. The Moon is at the top of the picture and beyond the Earth as viewed by Voyager. In the picture are eastern Asia, the western Pacific Ocean and part of the Arctic. Voyager 1 was directly above Mt. Everest (on the night side of the planet at 25 degrees north latitude) when the picture was taken. The photo was made from three images taken through color filters, then processed by the Jet Propulsion Laboratory's Image Processing Lab. Because the Earth is many times brighter than the Moon, the Moon was artificially brightened by a factor of three relative to the Earth by computer enhancement so that both bodies would show clearly in the print. Voyager 2 was launched Aug. 20, 1977, followed by Voyager 1 on Sept. 5, 1977, en route to encounters at Jupiter in 1979 and Saturn in 1980 and 1981. JPL manages the Voyager mission for NASA's Office of Space Science.

Photographer : JPL Range : 7 million kilometers (4.3 million miles) Io is Jupiter's innermost of the

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 7 million kilometers (4.3 million miles) Io is Jupiter's innermost of the four Galilean satellites. Photo taken at 2:00 AM through an ultraviolet filter. The photo's background is part of Jupiter's disk. North is at the top and the central longitude of Io is 180 degrees. Io shows a contrasting surface with dark polar areas and many light and dark regions around the equator. This resolution of about 100 miles/160 kilometers, no topographic features, like craters, can be seen. The brighter regions may be areas containing sulfur and various salts, making Io very reflective(six times brighter thanb Earth's Moon). Io is about the same size and density as our Moon, but has followed a different evolutionary path, influenced by its closeness to Jupiter and the intense bombardment it receives from the Jovian radiation belts of energetic charged particles.

Arrival and Departure at Jupiter

NASA Image and Video Library

2016-09-02

This montage of 10 JunoCam images shows Jupiter growing and shrinking in apparent size before and after NASA's Juno spacecraft made its closest approach on August 27, 2016, at 12:50 UTC. The images are spaced about 10 hours apart, one Jupiter day, so the Great Red Spot is always in roughly the same place. The small black spots visible on the planet in some of the images are shadows of the large Galilean moons. The images in the top row were taken during the inbound leg of the orbit, beginning on August 25 at 13:15 UTC when Juno was 1.4 million miles (2.3 million kilometers) away from Jupiter, and continuing to August 27 at 04:45 UTC when the spacecraft was 430,000 miles (700,000 kilometers) away. The images in the bottom row were obtained during the outbound leg of the orbit. They begin on August 28 at 00:45 UTC when Juno was 750,000 miles (920,000 kilometers) away and continue to August 29 at 16:45 UTC when the spacecraft was 1.6 million miles (2.5 million kilometers) away. http://photojournal.jpl.nasa.gov/catalog/PIA21034

Did Triton Destroy Neptune's First Moons?

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-11-01

Neptunes moon system is not what we would expect for a gas giant in our solar system. Scientists have now explored the possibility that Neptune started its life with an ordinary system of moons that was later destroyed by the capture of its current giant moon, Triton.An Odd SystemOur current understanding of giant-planet formation predicts a period of gas accretion to build up the large size of these planets. According to models, the circumplanetary gas disks that surround the planets during this time then become the birthplaces of the giant planets satellite systems, producing systems of co-planar and prograde (i.e., orbiting in the same direction as the planets rotation) satellites similar to the many-moon systems of Jupiter or Saturn.Tritons orbit is tilted relative to the inner Neptunian satellite orbits. [NASA, ESA, and A. Feild (STScI)]Neptune, however, is quirky. This gas giant has surprisingly few satellites only 14 compared to, say, the nearly 70 moons of Jupiter and most of them are extremely small. One of Neptunes moons is an exception to this, however: Triton, which contains 99.7% of the mass of Neptunes entire satellite system!Tritons orbit has a number of unusual properties. The orbit is retrograde Triton orbits in the opposite direction as Neptunes rotation which is unique behavior among large moons in our solar system. Tritons orbit is also highly inclined, and yet the moons path is nearly circular and lies very close to Neptune.The distribution of impact velocities in the authors simulations for primordial satellite interactions with Triton, in three cases of different satellite mass ratios. In the low-mass case a third of the mass ratio of the Uranian satellite system 88% of simulations ended with Triton surviving on its high-inclination orbit. The survival rate was only 12% in the high-mass case. [Adapted from Rufu et al. 2017]How did this monster of a satellite get its strange properties, and why is Neptunes system so odd compared to what we

Seismic detectability of meteorite impacts on Europa

NASA Astrophysics Data System (ADS)

Tsuji, Daisuke; Teanby, Nicholas

2016-04-01

Europa, the second of Jupiter's Galilean satellites, has an icy outer shell, beneath which there is probably liquid water in contact with a rocky core. Europa, may thus provide an example of a sub-surface habitable environment so is an attractive object for future lander missions. In fact, the Jupiter Icy Moon Explorer (JUICE) mission has been selected for the L1 launch slot of ESA's Cosmic Vision science programme with the aim of launching in 2022 to explore Jupiter and its potentially habitable icy moons. One of the best ways to probe icy moon interiors in any future mission will be with a seismic investigation. Previously, the Apollo seismic experiment, installed by astronauts, enhanced our knowledge of the lunar interior. For a recent mission, NASA's 2016 InSight Mars lander aims to obtain seismic data and will deploy a seismometer directly onto Mars' surface. Motivated by these works, in this study we show how many meteorite impacts will be detected using a single seismic station on Europa, which will be useful for planning the next generation of outer solar system missions. To this end, we derive: (1) the current small impact flux on Europa from Jupiter impact rate models; (2) a crater diameter versus impactor energy scaling relation for ice by merging previous experiments and simulations; (3) scaling relations for seismic signals as a function of distance from an impact site for a given crater size based on analogue explosive data obtained on Earth's icy surfaces. Finally, resultant amplitudes are compared to the noise level of a likely seismic instrument (based on the NASA InSight mission seismometers) and the number of detectable impacts are estimated. As a result, 0.5-3.0 local/regional small impacts (i.e., direct P-waves through the ice crust) are expected to be detected per year, while global-scale impact events (i.e., PKP-waves refracted through the mantle) are rare and unlikely to be detected by a short duration mission. We note that our results are

Simulating Extraterrestrial Ices in the Laboratory

NASA Astrophysics Data System (ADS)

Berisford, D. F.; Carey, E. M.; Hand, K. P.; Choukroun, M.

2017-12-01

Several ongoing experiments at JPL attempt to simulate the ice environment for various regimes associated with icy moons. The Europa Penitent Ice Experiment (EPIX) simulates the surface environment of an icy moon, to investigate the physics of ice surface morphology growth. This experiment features half-meter-scale cryogenic ice samples, cryogenic radiative sink environment, vacuum conditions, and diurnal cycling solar simulation. The experiment also includes several smaller fixed-geometry vacuum chambers for ice simulation at Earth-like and intermediate temperature and vacuum conditions for development of surface morphology growth scaling relations. Additionally, an ice cutting facility built on a similar platform provides qualitative data on the mechanical behavior of cryogenic ice with impurities under vacuum, and allows testing of ice cutting/sampling tools relevant for landing spacecraft. A larger cutting facility is under construction at JPL, which will provide more quantitative data and allow full-scale sampling tool tests. Another facility, the JPL Ice Physics Laboratory, features icy analog simulant preparation abilities that range icy solar system objects such as Mars, Ceres and the icy satellites of Saturn and Jupiter. In addition, the Ice Physics Lab has unique facilities for Icy Analog Tidal Simulation and Rheological Studies of Cryogenic Icy Slurries, as well as equipment to perform thermal and mechanical properties testing on icy analog materials and their response to sinusoidal tidal stresses.

Family Portrait of the Small Inner Satellites of Jupiter

NASA Technical Reports Server (NTRS)

1997-01-01

These images, taken by Galileo's solid state imaging system between November 1996 and June 1997, provide the first ever 'family portrait' of the four small, irregularly shaped moons that orbit Jupiter in the zone between the planet's ring and the larger Galilean satellites. The moons are shown in their correct relative sizes, with north approximately up in all cases. From left to right, arranged in order of increasing distance from Jupiter, are Metis (longest dimension is approximately 60 kilometers or 37 miles across), Adrastea (20 kilometers or 12 miles across), Amalthea (247 kilometers or 154 miles across), and Thebe (116 kilometers or 72 miles across). While Amalthea, the largest of these four tiny moons, was imaged by NASA's two Voyager spacecraft in 1979 with a resolution comparable to what is shown here, the new Galileo observations represent the first time that Metis, Adrastea, and Thebe have been seen as more than points of light.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Recent Simulations of the Late Stages Growth of Jupiter

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.; D'Angelo, Gennaro; Hubickyj, Olenka

2012-01-01

Presented by Lissauer et al. (2009, Icarus 199, 338) are used to test the model of capture of Jupiter's irregular satellites within proto-Jupiter's distended and thermally-supported envelope. We find such capture highly unlikely, since the envelope shrinks too slowly for a large number of moons to be retained, and many of those that would be retained would orbit closer to the planet than do the observed Jovian irregulars. Our calculations do not address (and therefore do not exclude) the possibility that the irregular satellites were captured as a result of gas drag within a circumjovian disk. Support for this research from NASA Outer Planets Research Program is gratefully acknowledged.

Salt partitioning between water and high-pressure ices. Implication for the dynamics and habitability of icy moons and water-rich planetary bodies

NASA Astrophysics Data System (ADS)

Journaux, Baptiste; Daniel, Isabelle; Petitgirard, Sylvain; Cardon, Hervé; Perrillat, Jean-Philippe; Caracas, Razvan; Mezouar, Mohamed

2017-04-01

Water-rich planetary bodies including large icy moons and ocean exoplanets may host a deep liquid water ocean underlying a high-pressure icy mantle. The latter is often considered as a limitation to the habitability of the uppermost ocean because it would limit the availability of nutrients resulting from the hydrothermal alteration of the silicate mantle located beneath the deep ice layer. To assess the effects of salts on the physical properties of high-pressure ices and therefore the possible chemical exchanges and habitability inside H2O-rich planetary bodies, we measured partitioning coefficients and densities in the H2O-RbI system up to 450 K and 4 GPa; RbI standing as an experimentally amenable analog of NaCl in the H2O-salt solutions. We measured the partitioning coefficient of RbI between the aqueous fluid and ices VI and VII, using in-situ Synchrotron X-ray Fluorescence (XRF). With in-situ X-ray diffraction, we measured the unit-cell parameters and the densities of the high-pressure ice phases in equilibrium with the aqueous fluid, at pressures and temperatures relevant to the interior of planetary bodies. We conclude that RbI is strongly incompatible towards ice VI with a partitioning coefficient Kd(VI-L) = 5.0 (± 2.1) ṡ10-3 and moderately incompatible towards ice VII, Kd(VII-L) = 0.12 (± 0.05). RbI significantly increases the unit-cell volume of ice VI and VII by ca. 1%. This implies that RbI-poor ice VI is buoyant compared to H2O ice VI while RbI-enriched ice VII is denser than H2O ice VII. These new experimental results might profoundly impact the internal dynamics of water-rich planetary bodies. For instance, an icy mantle at moderate conditions of pressure and temperature will consist of buoyant ice VI with low concentration of salt, and would likely induce an upwelling current of solutes towards the above liquid ocean. In contrast, a deep and/or thick icy mantle of ice VII will be enriched in salt and hence would form a stable chemical boundary

Microbial Extremophiles in Evolutionary Aspect

NASA Technical Reports Server (NTRS)

Pikuta, Elena V.; Hoover, Richard B.

2007-01-01

The microflora of the cryosphere of planet Earth provides the best analogs for life forms that might be found in the permafrost or polar ice caps of Mars, near the surface of the cometary nuclei, or in the liquid water beneath the ice crusts of icy moons of Jupiter and Saturn. For astrobiology the focus on the study alkaliphilic microorganisms was enhanced by the findings of abundant carbonates and carbonate globules rimmed with possibly biogenic magnetites in association with the putative microfossils in the ALH84001 meteorite. Although the ALH84001 "nanofossils" were to small and simple to be unambiguously recognized as biogenic, they stimulated Astrobiology research and studies of microbial extremophiles and biomarkers in ancient rocks and meteorites. Recent studies of CI and CM carbonaceous meteorites have resulted in the detection of the well-preserved mineralized remains of coccoidal and" filamentous microorganisms in cyanobacterial mats. Energy Dispersive X-ray Analysis has shown anomalous biogenic element ratios clearly indicating they are not recent biological contaminants. This paper reviews microbial extremophiles in context of their significance to Astrobiology and the evolution of life. Extremophilic microorganisms on Earth are models for life that might endure high radiation environments in the ice near the surface of comets or on the icy moons of Jupiter and Saturn and in the seafloor deep beneath the icy crusts of Europa and Enceladus.

Europa and Callisto under the watchful gaze of Jupiter

NASA Technical Reports Server (NTRS)

2000-01-01

One moment in an ancient, orbital dance is caught in this color picture taken by NASA's Cassini spacecraft on Dec. 7, 2000, just as two of Jupiter's four major moons, Europa and Callisto, were nearly perfectly aligned with each other and the center of the planet.

The distances are deceiving. Europa, seen against Jupiter, is 600,000 kilometers (370,000 miles) above the planet's cloud tops. Callisto, at lower left, is nearly three times that distance from the cloud tops. Europa is a bit smaller than Earth's Moon and has one of the brightest surfaces in the solar system. Callisto is 50 percent bigger -- roughly the size of Saturn's largest satellite, Titan -- and three times darker than Europa. Its brightness had to be enhanced in this picture, relative Europa's and Jupiter's, in order for Callisto to be seen in this image.

Europa and Callisto have had very different geologic histories but share some surprising similarities, such as surfaces rich in ice. Callisto has apparently not undergone major internal compositional stratification, but Europa's interior has differentiated into a rocky core and an outer layer of nearly pure ice. Callisto's ancient surface is completely covered by large impact craters: The brightest features seen on Callisto in this image were discovered by the Voyager spacecraft in 1979 to be bright craters, like those on our Moon. In contrast, Europa's young surface is covered by a wild tapestry of ridges, chaotic terrain and only a handful of large craters.

Recent data from the magnetometer carried by the Galileo spacecraft, which has been in orbit around Jupiter since 1995, indicate the presence of conducting fluid, most likely salty water, inside both worlds.

Scientists are eager to discover whether the surface of Saturn's Titan resembles that of Callisto or Europa, or whether it is entirely different when Cassini finally reaches its destination in 2004.

Cassini is a cooperative project of NASA, the European Space Agency and

Trapped particle absorption by the Ring of Jupiter

NASA Technical Reports Server (NTRS)

Fillius, W.

1983-01-01

The interaction of trapped radiation with the ring of Jupiter is investigated. Because it is an identical problem, the rings of Saturn and Uranus are also examined. Data from the Pioneer II encounter, deductions for some of the properties of the rings of Jupiter and Saturn. Over a dozen Jupiter magnetic field models are available in a program that integrates the adiabatic invariants to compute B and L. This program is to label our UCSD Pioneer II encounter data with the most satisfactory of these models. The expected effects of absorbing material on the trapped radiation are studied to obtain the loss rate as a function of ring properties. Analysis of the particle diffusion problem rounds out the theoretical end of the ring absorption problem. Other projects include identification of decay products for energetic particle albedo off the rings and moons of Saturn and a search for flux transfer events at the Jovian magnetopause.

Water and Volatiles in the Outer Solar System

NASA Astrophysics Data System (ADS)

Grasset, O.; Castillo-Rogez, J.; Guillot, T.; Fletcher, L. N.; Tosi, F.

2017-10-01

Space exploration and ground-based observations have provided outstanding evidence of the diversity and the complexity of the outer solar system. This work presents our current understanding of the nature and distribution of water and water-rich materials from the water snow line to the Kuiper Belt. This synthesis is timely, since a thorough exploration of at least one object in each region of the outer solar system has now been achieved. Next steps, starting with the Juno mission now in orbit around Jupiter, will be more focused on understanding the processes at work than on describing the general characteristics of each giant planet systems. This review is organized in three parts. First, the nature and the distribution of water and volatiles in giant and intermediary planets are described from their inner core to their outer envelopes. A special focus is given to Jupiter and Saturn, which are much better understood than the two ice giants (Uranus and Neptune) thanks to the Galileo and Cassini missions. Second, the icy moons will be discussed. Space missions and ground-based observations have revealed the variety of icy surfaces in the outer system. While Europa, Enceladus, and maybe Titan present past or even active tectonic and volcanic activities, many other moons have been dead worlds for more than 3 billion years. Ice compositions found at these bodies are also complex and it is now commonly admitted that icy surfaces are never composed of pure ices. A detailed review of the distribution of non-ice materials on the surfaces and in the tenuous atmospheres of the moons is proposed, followed by a more focused discussion on the nature and the characteristics of the liquid layers trapped below the cold icy crusts that have been suggested in the icy Galilean moons, and in Enceladus, Dione, and Titan at Saturn. Finally, the recent observations collected by Dawn at Ceres and New Horizons at Pluto, as well as the state of knowledge of other transneptunian objects

Uranus' largest moon Oberon

NASA Technical Reports Server (NTRS)

1986-01-01

Uranus' outermost and largest moon, Oberon, is seen in this Voyager 2 image, obtained Jan. 22, 1986, from a distance of 2.77 million kilometers (1.72 million miles). The clear-filter image, shuttered by Voyager's narrow-angle camera, shows that Oberon displays several distinct highly reflective (high-albedo) patches with low-albedo centers. Some of the bright patches are suggestive of radial patterns that could represent impact craters excavated from an icy surface. On average, Oberon reflects about 20 percent of the incident sunlight. The moon is about 1,600 km (1,000 mi) in diameter; resolution of this image is 51 km (32 mi). It was taken two days before Voyager's closest approach to Oberon, at which point the spacecraft will be about 471,000 km (293,000 mi) away. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.

Crescent-shaped Earth and Moon

NASA Technical Reports Server (NTRS)

1978-01-01

This picture of a crescent-shaped Earth and Moon -- the first of its kind ever taken by a spacecraft -- was recorded Sept. 18, 1977, by NASA's Voyager 1 when it was 7.25 million miles (11.66 million kilometers) from Earth. The Moon is at the top of the picture and beyond the Earth as viewed by Voyager. In the picture are eastern Asia, the western Pacific Ocean and part of the Arctic. Voyager 1 was directly above Mt. Everest (on the night side of the planet at 25 degrees north latitude) when the picture was taken. The photo was made from three images taken through color filters, then processed by the Jet Propulsion Laboratory's Image Processing Lab. Because the Earth is many times brighter than the Moon, the Moon was artificially brightened by a factor of three relative to the Earth by computer enhancement so that both bodies would show clearly in the print. Voyager 2 was launched Aug. 20, 1977, followed by Voyager 1 on Sept. 5, 1977, en route to encounters at Jupiter in 1979 and Saturn in 1980 and 1981. JPL manages the Voyager mission for NASA.

Compositional mapping of planetary moons by mass spectrometry of dust ejecta

NASA Astrophysics Data System (ADS)

Postberg, Frank; Grün, Eberhard; Horanyi, Mihaly; Kempf, Sascha; Krüger, Harald; Schmidt, Jürgen; Spahn, Frank; Srama, Ralf; Sternovsky, Zoltan; Trieloff, Mario

2011-11-01

Classical methods to analyze the surface composition of atmosphereless planetary objects from an orbiter are IR and gamma ray spectroscopy and neutron backscatter measurements. The idea to analyze surface properties with an in-situ instrument has been proposed by Johnson et al. (1998). There, it was suggested to analyze Europa's thin atmosphere with an ion and neutral gas spectrometer. Since the atmospheric components are released by sputtering of the moon's surface, they provide a link to surface composition. Here we present an improved, complementary method to analyze rocky or icy dust particles as samples of planetary objects from which they were ejected. Such particles, generated by the ambient meteoroid bombardment that erodes the surface, are naturally present on all atmosphereless moons and planets. The planetary bodies are enshrouded in clouds of ballistic dust particles, which are characteristic samples of their surfaces. In situ mass spectroscopic analysis of these dust particles impacting onto a detector of an orbiting spacecraft reveals their composition. Recent instrumental developments and tests allow the chemical characterization of ice and dust particles encountered at speeds as low as 1 km/s and an accurate reconstruction of their trajectories. Depending on the sampling altitude, a dust trajectory sensor can trace back the origin of each analyzed grain with about 10 km accuracy at the surface. Since the detection rates are of the order of thousand per orbit, a spatially resolved mapping of the surface composition can be achieved. Certain bodies (e.g., Europa) with particularly dense dust clouds, could provide impact statistics that allow for compositional mapping even on single flybys. Dust impact velocities are in general sufficiently high at orbiters about planetary objects with a radius >1000 km and with only a thin or no atmosphere. In this work we focus on the scientific benefit of a dust spectrometer on a spacecraft orbiting Earth's Moon as

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.

Capture of irregular satellites at Jupiter

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

Nesvorný, David; Vokrouhlický, David; Deienno, Rogerio

The irregular satellites of outer planets are thought to have been captured from heliocentric orbits. The exact nature of the capture process, however, remains uncertain. We examine the possibility that irregular satellites were captured from the planetesimal disk during the early solar system instability when encounters between the outer planets occurred. Nesvorný et al. already showed that the irregular satellites of Saturn, Uranus, and Neptune were plausibly captured during planetary encounters. Here we find that the current instability models present favorable conditions for capture of irregular satellites at Jupiter as well, mainly because Jupiter undergoes a phase of close encountersmore » with an ice giant. We show that the orbital distribution of bodies captured during planetary encounters provides a good match to the observed distribution of irregular satellites at Jupiter. The capture efficiency for each particle in the original transplanetary disk is found to be (1.3-3.6) × 10{sup –8}. This is roughly enough to explain the observed population of jovian irregular moons. We also confirm Nesvorný et al.'s results for the irregular satellites of Saturn, Uranus, and Neptune.« less

Formation of relief on Europa's surface and analysis of a melting probe movement through the ice

NASA Astrophysics Data System (ADS)

Erokhina, O. S.; Chumachenko, E. N.; Dunham, D. W.; Aksenov, S. A.; Logashina, I. V.

2013-12-01

These days, studies of planetary bodies' are of great interest. And of special interest are the icy moons of the giant planets like Jupiter and Saturn. Analysis of 'Voyager 1', 'Voyager 2', 'Galileo' and 'Cassini' spacecraft data showed that icy covers were observed on Jupiter's moons Ganymede, Europa and Calisto, and Saturn's moons Titan and Enceladus. Of particular interest is the relatively smooth surface of Europa. The entire surface is covered by a system of bands, valleys, and ridges. These structures are explained by the mobility of surface ice, and the impact of stress and large-scale tectonic processes. Also conditions on these moons allow speculation about possible life, considering these moons from an astrobiological point of view. To study the planetary icy body in future space missions, one of the problems to solve is the problem of design of a special device capable of penetrating through the ice, as well as the choice of the landing site of this probe. To select a possible landing site, analysis of Europa's surface relief formation is studied. This analysis showed that compression, extention, shearing, and bending can influence some arbitrarily separated section of Europe's icy surface. The computer simulation with the finite element method (FEM) was performed to see what types of defects could arise from such effects. The analysis showed that fractures and cracks could have various forms depending on the stress-strained state arising in their vicinity. Also the problem of a melting probe's movement through the ice is considered: How the probe will move in low gravity and low atmospheric pressure; whether the hole formed in the ice will be closed when the probe penetrates far enough or not; what is the influence of the probe's characteristics on the melting process; what would be the order of magnitude of the penetration velocity. This study explores the technique based on elasto-plastic theory and so-called 'solid water' theory to estimate the

Electron Density Measurement on JUICE Mission by Mutual Impedance Technique: MIME Instrument as a Part of RPWI Consortium

NASA Astrophysics Data System (ADS)

Rauch, J. L.; Henri, P.; Wahlund, J. E.; Le Duff, O.; Sene, O.; Colin, F.; Lagoutte, D.; Gilet, N.; Ahlen, L.; Bergman, J.; Gill, R.; Puccio, W.

2017-09-01

Mutual Impedance MEasurements (MIME) instrument is a part of the Radio Wave Plasma Investigation (RPWI) consortium which has been selected by European Space Agency (ESA) on the nest planetary mission JJUpiter ICy moons Exploer (JUICE) for a launch in 2022. The goals are to explore Jupiter and its potentially habitable icy moons and to study its plasma environment. Impedance probes, which are well known in geophysical prospection, in particular for ground permittivity investigations, have been successfully transposed to space plasmas diagnostic. Transmitting and receiving electrodes are used for measuring on open circuit the dynamic impedance of the system at several fixed frequencies over a range that includes characteristic frequencies of the ambient plasma. The measurements are then interpreted using a suitable theory and the values of plasma parameters, such as the electron density and possibly the temperature of the plasma can be deduced. To show how powerful this technique is, results obtained in the Earth's plasmasphere by the mutual impedance probe onboard ROSETTA are presented as example. MIME instrument proposal is then described and its ability to make valuable measurements in the Jupiter space environment and in particular around Europe, Callisto and Ganymede is investigated..

Energetic neutral atoms from a trans-Europa gas torus at Jupiter.

PubMed

Mauk, B H; Mitchell, D G; Krimigis, S M; Roelof, E C; Paranicas, C P

2003-02-27

The space environments--or magnetospheres--of magnetized planets emit copious quantities of energetic neutral atoms (ENAs) at energies between tens of electron volts to hundreds of kiloelectron volts (keV). These energetic atoms result from charge exchange between magnetically trapped energetic ions and cold neutral atoms, and they carry significant amounts of energy and mass from the magnetospheres. Imaging their distribution allows us to investigate the structure of planetary magnetospheres. Here we report the analysis of 50-80 keV ENA images of Jupiter's magnetosphere, where two distinct emission regions dominate: the upper atmosphere of Jupiter itself, and a torus of emission residing just outside the orbit of Jupiter's satellite Europa. The trans-Europa component shows that, unexpectedly, Europa generates a gas cloud comparable in gas content to that associated with the volcanic moon Io. The quantity of gas found indicates that Europa has a much greater impact than hitherto believed on the structure of, and the energy flow within, Jupiter's magnetosphere.

The Impact of a Large Object on Jupiter in 2009 July

NASA Technical Reports Server (NTRS)

Sanchez-Lavega, A.; Wesley, A.; Orton, G.; Hueso, R.; Perez-Hoyos, S.; Fletcher, L. N.; Yanamandra-Fisher, P.; Legarreta, J.; de Pater, I.; Hammel, H.;

Orbit determination strategy and results for the Pioneer 10 Jupiter mission

NASA Technical Reports Server (NTRS)

Wong, S. K.; Lubeley, A. J.

1974-01-01

Pioneer 10 is the first earth-based vehicle to encounter Jupiter and occult its moon, Io. In contributing to the success of the mission, the Orbit Determination Group evaluated the effects of the dominant error sources on the spacecraft's computed orbit and devised an encounter strategy minimizing the effects of these error sources. The encounter results indicated that: (1) errors in the satellite model played a very important role in the accuracy of the computed orbit, (2) encounter strategy was sound, (3) all mission objectives were met, and (4) Jupiter-Saturn mission for Pioneer 11 is within the navigation capability.

Time Series of Jupiter Aurora

NASA Image and Video Library

1998-06-10

These mosaics of Jupiter's night side show the Jovian aurora at approximately 45 minute intervals as the auroral ring rotated with the planet below the spacecraft. The images were obtained by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. during its eleventh orbit of Jupiter. The auroral ring is offset from Jupiter's pole of rotation and reaches the lowest latitude near 165 degrees west longitude. The aurora is hundreds of kilometers wide, and when it crosses the edge of Jupiter, it is about 250 kilometers above the planet. As on Earth, the auroral emission is caused by electrically charged particles striking atoms in the upper atmosphere from above. The particles travel along Jupiter's magnetic field lines, but their origin is not fully understood. The field lines where the aurora is most intense cross the Jovian equator at large distances (many Jovian radii) from the planet. The faint background throughout the image is scattered light in the camera. This stray light comes from the sunlit portion of Jupiter, which is out of the image. In multispectral observations the aurora appears red, consistent with how atomic hydrogen in Jupiter's atmosphere would glow. Galileo's unique perspective allows it to view the night side of the planet at short range, revealing details that cannot be seen from Earth. These detailed features are time dependent, and can be followed in this sequence of Galileo images. In the first mosaic, the auroral ring is directly over Jupiter's limb and is seen "edge on." In the fifth mosaic, the auroral emission is coming from several distinct bands. This mosaic also shows the footprint of the Io flux tube. Volcanic eruptions on Jupiter's moon, Io, spew forth particles that become ionized and are pulled into Jupiter's magnetic field to form an invisible tube, the Io flux tube, between Jupiter and Io. The bright circular feature towards the lower right may mark the location where these energetic particles impact Jupiter. Stars

Clump detections and limits on moons in Jupiter's ring system.

PubMed

Showalter, Mark R; Cheng, Andrew F; Weaver, Harold A; Stern, S Alan; Spencer, John R; Throop, Henry B; Birath, Emma M; Rose, Debi; Moore, Jeffrey M

2007-10-12

The dusty jovian ring system must be replenished continuously from embedded source bodies. The New Horizons spacecraft has performed a comprehensive search for kilometer-sized moons within the system, which might have revealed the larger members of this population. No new moons were found, however, indicating a sharp cutoff in the population of jovian bodies smaller than 8-kilometer-radius Adrastea. However, the search revealed two families of clumps in the main ring: one close pair and one cluster of three to five. All orbit within a brighter ringlet just interior to Adrastea. Their properties are very different from those of the few other clumpy rings known; the origin and nonrandom distribution of these features remain unexplained, but resonant confinement by Metis may play a role.

JUICE: complementarity of the payload in adressing the mission science objectives

NASA Astrophysics Data System (ADS)

Titov, Dmitri; Barabash, Stas; Bruzzone, Lorenzo; Dougherty, Michele; Erd, Christian; Fletcher, Leigh; Gare, Philippe; Gladstone, Randall; Grasset, Olivier; Gurvits, Leonid; Hartogh, Paul; Hussmann, Hauke; Iess, Luciano; Jaumann, Ralf; Langevin, Yves; Palumbo, Pasquale; Piccioni, Giuseppe; Wahlund, Jan-Erik

2014-05-01

JUpiter ICy moons Explorer (JUICE) will perform detailed investigations of Jupiter and its system with particular emphasis on Ganymede as a planetary body and potential habitat. The overarching theme for JUICE is: The emergence of habitable worlds around gas giants. At Ganymede, the mission will characterize in detail the ocean layers; provide topographical, geological and compositional mapping of the surface; study the physical properties of the icy crusts; characterize the internal mass distribution, investigate the exosphere; study Ganymede's intrinsic magnetic field and its interactions with the Jovian magnetosphere. For Europa, the focus will be on the non-ice chemistry, understanding the formation of surface features and subsurface sounding of the icy crust over recently active regions. Callisto will be explored as a witness of the early solar system. JUICE will perform a multidisciplinary investigation of the Jupiter system as an archetype for gas giants. The circulation, meteorology, chemistry and structure of the Jovian atmosphere will be studied from the cloud tops to the thermosphere. The focus in Jupiter's magnetosphere will include an investigation of the three dimensional properties of the magnetodisc and in-depth study of the coupling processes within the magnetosphere, ionosphere and thermosphere. Aurora and radio emissions will be elucidated. JUICE will study the moons' interactions with the magnetosphere, gravitational coupling and long-term tidal evolution of the Galilean satellites. JUICE highly capable scientific payload includes 10 state-of-the-art instruments onboard the spacecraft plus one experiment that uses the spacecraft telecommunication system with ground-based radio telescopes. The remote sensing package includes a high-resolution multi-band visible imager (JANUS) and spectro-imaging capabilities from the ultraviolet to the sub-millimetre wavelengths (MAJIS, UVS, SWI). A geophysical package consists of a laser altimeter (GALA) and a

Distinct Aqueous and Hydrocarbon Cryovolcanism on Titan and Other Icy Satellites (Invited)

NASA Astrophysics Data System (ADS)

Kargel, J. S.; Furfaro, R.; Candelaria, P.

2010-12-01

Almost as soon as low-temperature solar nebula condensation sequences were first computed, it was realized that icy satellites have an internal heat source in long-lived radioactivities and could undergo differentiation; furthermore, freezing-point depressants, such as ammonia, and apolar gases, such as methane, could enable icy satellites to undergo aqueous cryovolcanism. The subsequent recognition of tidal and gravitational potential energy sources increased expectations for cryovolcanism. Voyager imaging and discovery of apparent cryovolcanic landforms—best exhibited by Triton, more ambiguous elsewhere-- motivated studies of the phase relations, phase densities and other thermodynamic properties, solid- and liquid-state rheologies, and possible cryovolcanic eruptive behaviors and landform characteristics. Ironically, the closer we examined Jovian icy moons with Galileo, the rarer cryovolcanic landforms appeared to be, with only a few compelling and very well characterized cases found mainly on Europa. Compelling examples of effusive cryovolcanism mainly occupied local topographic lows, whereas cases not in low spots tended to exhibit signs of explosive emplacement. Spectacular evidence of explosive cryovolcanism or geyser-like behavior was found by Cassini on Enceladus, but most other icy Saturnian moons did not reveal any compelling indicators of eruptions. Titan has so far been a mixed case, where some indicators of cryovolcanism have been reported, but there is scant compelling evidence for the process. We think that the sparseness of compelling effusive cryovolcanic features on icy satellites is because free, unreacted ammonia is less common than previously thought, and the main aqueous liquids are salt-water solutions denser than ice I; hence, they tend not to erupt, or they erupt only if driven by gas exsolution; even then, a thin ice shell and high heat flow is needed to allow aqueous liquids near enough to the surface to erupt. On satellites with thick

Sample Processor for Life on Icy Worlds (SPLIce): Design and Test Results

NASA Technical Reports Server (NTRS)

Chinn, Tori N.; Lee, Anthony K.; Boone, Travis D.; Tan, Ming X.; Chin, Matthew M.; McCutcheon, Griffin C.; Horne, Mera F.; Padgen, Michael R.; Blaich, Justin T.; Forgione, Joshua B.;

Habitable moons around extrasolar giant planets

NASA Technical Reports Server (NTRS)

Williams, D. M.; Kasting, J. F.; Wade, R. A.

1997-01-01

Possible planetary objects have now been discovered orbiting nine different main-sequence stars. These companion objects (some of which might actually be brown dwarfs) all have a mass at least half that of Jupiter, and are therefore unlikely to be hospitable to Earth-like life: jovian planets and brown dwarfs support neither a solid nor a liquid surface near which organisms might dwell. Here we argue that rocky moons orbiting these companions could be habitable if the planet-moon system orbits the parent star within the so-called 'habitable zone', where life-supporting liquid water could be present. The companions to the stars 16 Cygni B and 47 Ursae Majoris might satisfy this criterion. Such a moon would, however, need to be large enough (>0.12 Earth masses) to retain a substantial and long-lived atmosphere, and would also need to possess a strong magnetic field in order to prevent its atmosphere from being sputtered away by the constant bombardment of energetic ions from the planet's magnetosphere.

Habitable moons around extrasolar giant planets.

PubMed

Williams, D M; Kasting, J F; Wade, R A

1997-01-16

Possible planetary objects have now been discovered orbiting nine different main-sequence stars. These companion objects (some of which might actually be brown dwarfs) all have a mass at least half that of Jupiter, and are therefore unlikely to be hospitable to Earth-like life: jovian planets and brown dwarfs support neither a solid nor a liquid surface near which organisms might dwell. Here we argue that rocky moons orbiting these companions could be habitable if the planet-moon system orbits the parent star within the so-called 'habitable zone', where life-supporting liquid water could be present. The companions to the stars 16 Cygni B and 47 Ursae Majoris might satisfy this criterion. Such a moon would, however, need to be large enough (>0.12 Earth masses) to retain a substantial and long-lived atmosphere, and would also need to possess a strong magnetic field in order to prevent its atmosphere from being sputtered away by the constant bombardment of energetic ions from the planet's magnetosphere.

Cryo-braking using penetrators for enhanced capabilities for the potential landing of payloads on icy solar system objects

NASA Astrophysics Data System (ADS)

Winglee, R. M.; Robinson, T.; Danner, M.; Koch, J.

2018-03-01

The icy moons of Jupiter and Saturn are important astrobiology targets. Access to the surface of these worlds is made difficult by the high ΔV requirements which is typically in the hypervelocity range. Passive braking systems cannot be used due to the lack of an atmosphere, and active braking by rockets significantly adds to the missions costs. This paper demonstrates that a two-stage landing system can overcome these problems and provide significant improvements in the payload fraction that can be landed The first stage involves a hypervelocity impactor which is designed to penetrate to a depth of a few tens of meters. This interaction is the cryo-breaking component and is examined through laboratory experiments, empirical relations and modeling. The resultant ice-particle cloud creates a transient artificial atmosphere that can be used to enable passive braking of the second stage payload dd, with a substantially higher mass payload fraction than possible with a rocket landing system. It is shown that a hollow cylinder design for the impactor can more efficiently eject the material upwards in a solid cone of ice particles relative to solid impactors such as spheres or spikes. The ejected mass is shown to be of the order of 103 to 104 times the mass of the impactor. The modeling indicates that a 10 kg payload with a braking system of 3 m2 (i.e. an areal density of 0.3 kg/m2) is sufficient to allow the landing of the payload with the deceleration limited to less than 2000 g's. Modern electronics can withstand this deceleration and as such the system provides an important alternative to landing payloads on icy solar system objects.

Photographer : JPL Range : 5.9 million kilometers (3.66 million miles) Europa is Jupiter's 2nd

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 5.9 million kilometers (3.66 million miles) Europa is Jupiter's 2nd Galilean satellites from the planet and the brightest. Photo taken early morning through violet filter. Faint swirls and linear patterns show in the equatorial region (which shows darker than the poles). This hemisphere always faces Jupiter. North is up. Density and size comparable to Earth's Moon and seems to show water ice or ground water on its surface.

Jupiter's Main Ring

NASA Technical Reports Server (NTRS)

1997-01-01

at 128,940 +/-50 km, slightly less than the Voyager value of 129,130 +/-100 km, but very close to the orbit of the satellite Adrastea (128,980 km). The main ring exhibits a marked drop in brightness at 127,849 +/-50 km, lying almost atop the orbit of the Jovian moon Metis at 127,978 km. Satellites seem to affect the structure of even tenuous rings like that found at Jupiter.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at: http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at: http:/ /www.jpl.nasa.gov/galileo/sepo.

Emergence of Habitable Environments in Icy World Interiors

NASA Astrophysics Data System (ADS)

Neveu, Marc

2016-07-01

Finding habitable worlds is a key driver of solar system exploration. Many solar system missions seek environments providing liquid water, energy, and nutrients, the three ingredients necessary to sustain life [1]. Such environments include hydrothermal systems, spatially confined systems where hot aqueous fluid circulates through rock by convection. Hydrothermal activity may be widespread in the solar system. Most solar system worlds larger than 200 km in radius are icy moons and dwarf planets, likely composed of an icy, cometary mantle surrounding a rocky, chondritic core [2]. By improving an icy world evolution code [3] to include the effects of core fracturing and hydrothermal circulation, I show that several icy moons and dwarf planets likely have undergone extensive water-rock interaction [4,5]. This supports observations of aqueous products on their surfaces [6,7]. I simulated the alteration of chondritic rock [8] by pure water or fluid of cometary composition [9] to show that aqueous alteration feeds back on geophysical evolution: it modifies the fluid antifreeze content, affecting its persistence over geological timescales; and the distribution of radionuclides, whose decay is a chief heat source on dwarf planets [10]. Hydrothermal circulation also efficiently transports heat from the core into the ocean, thereby increasing ocean persistence [4]. Thus, these coupled geophysical-geochemical models provide a comprehensive picture of icy world evolution and the emergence of liquid environments in chemical disequilibrium with underlying rock in their interiors. Habitable settings also require a suitable supply of bioessential elements; but what constitutes "suitable"? I sought to quantify the bulk elemental composition of hydrothermal microbial communities, collected in hot spring sediments and mats at Yellowstone National Park, USA. To do so, one must minimize the contribution of non-biological material to the samples analyzed. This was achieved using a

Predicting Juno Evidence for a Solid Methane Gas Hydrate Jupiter J. Ackerman Abstract

NASA Astrophysics Data System (ADS)

Ackerman, J. A., Jr.

2016-12-01

Predicting Juno Evidence for a Solid Methane Gas Hydrate Jupiter J. Ackerman AbstractDeuterium enhancements of 1010 observed in LDNs and heavy elements detected by the Galileo probe (C, O, S, Ar, Kr and Xe) suggest the giant planets accreted slow and cold from snowflakes and dust at their current orbits, forming frozen, highly deuterated Methane Gas Hydrate (d=0.9) bodies, together comprising > 300 earth masses of water. Jupiter also incorporated most of the heavy elements in the nascent solar system as dust grains (d=1.33). A recent (6,000 years BP) high energy impact on heavily deuterated Jupiter triggered a massive nuclear fusion explosion which ejected the Galilean moons, initiating a flaming plasma plume originally extending 2 x106 km, beyond Callisto. The rapidly rotating plume produced the physical differences observed on the Galilean moons and the remainder condensed ejecting millions of asteroids similar to 67P as it slowly diminished over 5000 years. The fusion reaction has diminished to d + p > 3He+ + γ, but is still producing Jupiter's atmospheric temperature excess, >5x1017 watts, and driving the multiple zonal wind vortices constrained below by Jupiter's solid surface. The mass being ejected by the plume measurably slowed the rotation of the giant Jupiter up until 1937. The highly energetic 3He+ ions from the fusion reaction that exit Jupiter through the Great Red Spot were sensed by Ulysses, Cassini and Galileo at distances greater than 11 Jupiter radii, with the period of Jupiter's rotation. The Juno JEDI particle detector will measure the speed and density of the 3He+ 'blizzard' exiting the GRS, for which there is no other explanation. The Micro Wave Radiometer (MWR) system will confirm the hot vortex extending below the cloud tops from the fusion reaction on the surface westward to the Great Red Spot at 22o S latitude, due to its estimated 115 degree longitudinal extent. The high intensity of the 3He+ particulate radiation at 4000 km directly

Detecting Darwinism from Molecules in the Enceladus Plumes, Jupiter's Moons, and Other Planetary Water Lagoons.

PubMed

Benner, Steven A

2017-09-01

To the astrobiologist, Enceladus offers easy access to a potential subsurface biosphere via the intermediacy of a plume of water emerging directly into space. A direct question follows: If we were to collect a sample of this plume, what in that sample, through its presence or its absence, would suggest the presence and/or absence of life in this exotic locale? This question is, of course, relevant for life detection in any aqueous lagoon that we might be able to sample. This manuscript reviews physical chemical constraints that must be met by a genetic polymer for it to support Darwinism, a process believed to be required for a chemical system to generate properties that we value in biology. We propose that the most important of these is a repeating backbone charge; a Darwinian genetic biopolymer must be a "polyelectrolyte." Relevant to mission design, such biopolymers are especially easy to recover and concentrate from aqueous mixtures for detection, simply by washing the aqueous mixtures across a polycharged support. Several device architectures are described to ensure that, once captured, the biopolymer meets two other requirements for Darwinism, homochirality and a small building block "alphabet." This approach is compared and contrasted with alternative biomolecule detection approaches that seek homochirality and constrained alphabets in non-encoded biopolymers. This discussion is set within a model for the history of the terran biosphere, identifying points in that natural history where these alternative approaches would have failed to detect terran life. Key Words: Enceladus-Life detection-Europa-Icy moon-Biosignatures-Polyelectrolyte theory of the gene. Astrobiology 17, 840-851.

Miniaturized Plasma and Neutral Diagnostics for JIMO

NASA Technical Reports Server (NTRS)

McHarg, M. G.; Enloe, C. L.; Krause, L. A.; Herrero, F. A.

2003-01-01

We describe a miniaturized suite of instruments which provides both bulk energy resolved plasma properties and coarse neutral mass spectroscopy suitable for measurements on the Jupiter Icy Moons Orbiter (JIMO). The suite is comprised of two instruments; the Miniaturized Electro-Static Analyzer (MESA), and the Flat Plasma Spectrometer (FLAPS), designed to measure the near earth environment on the Air Force Academy small satellite missions Falconsat-2 and 3.

The ESA JUICE mission: the Science and the Science Operations

NASA Astrophysics Data System (ADS)

Lorente, Rosario; Altobelli, Nicolas; Vallat, Claire; Munoz, Claudio; Andres, Rafael; Cardesin, Alejandro; Witasse, Olivier; Erd, Christian

2017-04-01

JUICE - JUpiter ICy moons Explorer - is the first large mission in the ESA Cosmic Vision 2015-2025 programme [1]. The mission was selected in May 2012 and adopted in November 2014. The implementation phase started in July 2015, following the selection of the prime industrial contractor, Airbus Defense and Space (Toulouse, France). Due to launch in May 2022 and arrival at Jupiter in October 2029, it will spend almost three years making detailed observations of the Jovian system, with a special focus on the planet itself, its giant magnetosphere, and the three icy moons: Ganymede, Callisto and Europa. In August 2032, JUICE will then orbit Ganymede for at least ten months. The first goal of JUICE is to characterize the conditions that might have led to the emergence of habitable environments among the Jovian satellites, with special emphasis on the three giant icy worlds, likely hosting internal oceans [2]. The second goal is to explore the Jupiter system as an archetype of gas giants. Focused studies of Jupiter's atmosphere and magnetosphere, and their interaction with the Galilean satellites will further enhance our understanding of the evolution and dynamics of the Jovian system. The JUICE payload consists of 10 state-of-the-art instruments plus one experiment that uses the spacecraft telecommunication system with ground-based instruments. This payload is capable of addressing all of the mission's science goals [1,2]. A remote sensing package includes imaging (JANUS) and spectral-imaging capabilities from the ultraviolet to the sub-millimetre wavelengths (MAJIS, UVS, SWI). A geophysical package consists of a laser altimeter (GALA) and a radar sounder (RIME) for exploring the surface and subsurface of the moons, and a radio science experiment (3GM) to probe the atmospheres of Jupiter and its satellites and to perform measurements of the gravity fields. An in situ package comprises a powerful suite to study plasma and neutral gas environments (PEP) with remote

Cryovolcanism in the outer solar system

USGS Publications Warehouse

Geissler, Paul E.

2015-01-01

Cryovolcanism is defined as the extrusion of liquids and vapors of materials that would be frozen solid at the planetary surface temperatures of the icy bodies of the outer solar system. Active cryovolcanism is now known to occur on Saturn's moon Enceladus and on Neptune's moon Triton and is suspected on Jupiter's moon Europa, while evidence for past cryovolcanic activity is widespread throughout the outer solar system. This chapter examines the mechanisms and manifestations of cryovolcanism, beginning with a review of the materials that make up these unusual ‘‘magmas’’ and the means by which they might erupt and concluding with a volcanologist's tour of the farthest reaches of the solar system.

Outer planets and icy satellites

NASA Technical Reports Server (NTRS)

Drobyshevski, E. M.

1991-01-01

The resources offered by the outer bodies in the Solar System, starting with the main belt asteroids and Jovian System, are not only larger and more diverse but may even be easier to reach than, say, those of Mars. The use of their material, including water and organic matter, depends exclusively on the general strategy of exploration of the Solar System. Of major interest in this respect are the large ice satellites - Titan, Ganymede, and Callisto. Motion through the planetary magnetospheres excites in their ice envelopes megampere currents which, in the presence of rocky, etc., inclusions with electronic conduction should lead to the bulk electrolysis of ice and accumulation in it of 2H2 + O2 in the form of a solid solution. With the concentration of 2H2 + O2 reaching about 15 wt. percent, the solution becomes capable of detonation by a strong meteoritic impact. An explosion of Ganymede's ice envelope about 0.5 By ago could account for the formation of the Trojans and irregular satellites, all known differences between Ganymede and Callisto, and many other things. The explosion of a small icy planet with M approx less than 0.5 Moon created the asteroid belt. Two to three explosions occurred on Io, and two on Europa. The specific features of the longperiod comets close to Saturn's orbit permit dating Titan's envelope explosion as 10,000 yr ago, which produced its thick atmosphere, young Saturn's rings, as well as a reservoir of ice fragments saturated by 2H2 + O2, i.e., cometary nuclei between the orbits of Jupiter and Saturn. Thus these nuclei should contain, besides organic matter, also 2H2 + O2, which could be used for their transportation as well as for fuel for spaceships. Ices of such composition can reside deep inside Deimos, the Trojans, C-asteroids, etc. The danger of a future explosion of Callisto's electrolyzed ices, which would result in a catastrophic bombardment of the Earth by comets, may be high enough to warrant a revision of the priorities and

Outer planets and icy satellites

NASA Astrophysics Data System (ADS)

Drobyshevski, E. M.

The resources offered by the outer bodies in the Solar System, starting with the main belt asteroids and Jovian System, are not only larger and more diverse but may even be easier to reach than, say, those of Mars. The use of their material, including water and organic matter, depends exclusively on the general strategy of exploration of the Solar System. Of major interest in this respect are the large ice satellites - Titan, Ganymede, and Callisto. Motion through the planetary magnetospheres excites in their ice envelopes megampere currents which, in the presence of rocky, etc., inclusions with electronic conduction should lead to the bulk electrolysis of ice and accumulation in it of 2H2 + O2 in the form of a solid solution. With the concentration of 2H2 + O2 reaching about 15 wt. percent, the solution becomes capable of detonation by a strong meteoritic impact. An explosion of Ganymede's ice envelope about 0.5 By ago could account for the formation of the Trojans and irregular satellites, all known differences between Ganymede and Callisto, and many other things. The explosion of a small icy planet with M approx less than 0.5 Moon created the asteroid belt. Two to three explosions occurred on Io, and two on Europa. The specific features of the longperiod comets close to Saturn's orbit permit dating Titan's envelope explosion as 10,000 yr ago, which produced its thick atmosphere, young Saturn's rings, as well as a reservoir of ice fragments saturated by 2H2 + O2, i.e., cometary nuclei between the orbits of Jupiter and Saturn. Thus these nuclei should contain, besides organic matter, also 2H2 + O2, which could be used for their transportation as well as for fuel for spaceships. Ices of such composition can reside deep inside Deimos, the Trojans, C-asteroids, etc. The danger of a future explosion of Callisto's electrolyzed ices, which would result in a catastrophic bombardment of the Earth by comets, may be high enough to warrant a revision of the priorities and

ARC-1994-AC94-0353-1

NASA Image and Video Library

1994-07-07

This is a composite photo, assembled from separate images of Jupiter and Comet P/Shoemaker-Levy 9 as imaged by the Wide Field & Planetary Camera-2 (WFPC-2), aboard NASA's Hubble Space Telescope (HST). Jupiter was imaged on May 18, 1994, when the giant planet was at a distance of 420 million miles (670 million KM) from Earth. This 'true-color' picture was assembled from separate HST exposures in red, blue, and green light. Jupiter's rotation between exposures creates the blue and red fringe on either side of the disk. HST can resolve details in Jpiter's magnifient cloud belts and zones as small as 200 miles (320 km) across (wide field mode). This detailed view is only surpassed by images from spacecraft that have traveled to Jupiter. The dark spot on the disk of Jupiter is the shadow of the inner moon Io. This volcanic moon appears as an orange and yellow disk just to the upper right of the shadow. Though Io is approximately the size of Earth's Moon (but 2,000 times farther away), HST can resolve surface details. When the comet was observed on May 17, its train of 21 icy fragments stretched across 710 thousand miles (1.1 million km) of space, or 3 times the distance between Earth and the Moon. This required six WFPC exposures along the comet train to include all the nuclei. The image was taken in red light. The apparent angular size of Jupiter relative to the comet, and its angular separation from the comet when the images were taken, have been modified for illustration purposes. CREDIT: H.A. Weaver, T.E. Smith (Space Telescope Science Institute (STSI)) and J.T. Tranuger, R.W. Evans (Jet Propulsion Laboratory (JPL)) and NASA. (HST ref: STSci-PR94-26a)

A 'Moving' Jupiter Global Map (Animation)

NASA Technical Reports Server (NTRS)

2007-01-01

condenses to form the plume tails, and with falling air in the dark areas just to the east of each plume.

The maps of Jupiter shown here do not include the polar regions, because those regions are not well seen by LORRI from its vantage point high above Jupiter's equatorial region. Shadows of Jupiter's moons (first of Io, then of Ganymede) appear in two of the maps. Name Dates Range from Jupiter [million km]

Image resolution element [km] JobsATM1 Jan 8-9, 2007 81.2 402 JobsATM2 Jan 9-10, 2007 79.9 396 JobsATM3 Jan 14-15, 2007 71.9 356 JobsATM4 Jan 15, 2007 70.5 349 JobsATM5 Jan 20-21, 2007 61.8 306 JobsATM6 Jan 21-22, 2007 60.5 300

Subsurface Ocean Tides in Enceladus and Other Icy Moons

NASA Astrophysics Data System (ADS)

Beuthe, M.

2016-12-01

Could tidal dissipation within Enceladus' subsurface ocean account for the observed heat flow? Earthlike models of dynamical tides give no definitive answer because they neglect the influence of the crust. I propose here the first model of dissipative tides in a subsurface ocean, by combining the Laplace Tidal Equations with the membrane approach. For the first time, it is possible to compute tidal dissipation rates within the crust, ocean, and mantle in one go. I show that oceanic dissipation is strongly reduced by the crustal constraint, and thus contributes little to Enceladus' present heat budget. Tidal resonances could have played a role in a forming or freezing ocean less than 100 meters deep. The model is general: it applies to all icy satellites with a thin crust and a shallow or stratified ocean. Scaling rules relate the resonances and dissipation rate of a subsurface ocean to the ones of a surface ocean. If the ocean has low viscosity, the westward obliquity tide does not move the crust. Therefore, crustal dissipation due to dynamical obliquity tides can differ from the static prediction by up to a factor of two.

New Radiation Zones on Jupiter

NASA Image and Video Library

2017-12-11

This graphic shows a new radiation zone surrounding Jupiter, located just above the atmosphere near the equator, that has been discovered by NASA's Juno mission. The new radiation zone is depicted here as a glowing blue area around the planet's middle. This radiation zone includes energetic hydrogen, oxygen and sulfur ions moving at close to the speed of light (referred to as "relativistic" speeds). It resides inside Jupiter's previously known radiation belts. The zone was identified by the mission's Jupiter Energetic Particle Detector Instrument (JEDI), enabled by Juno's unique close approach to the planet during the spacecraft's science flybys (2,100 miles or 3,400 kilometers from the cloud tops). Juno scientists believe the particles creating this region of intense radiation are derived from energetic neutral atoms -- that is, fast-moving atoms without an electric charge -- coming from the tenuous gas around Jupiter's moons Io and Europa. The neutral atoms then become ions -- atoms with an electric charge -- as their electrons are stripped away by interaction with the planet's upper atmosphere. (This discovery is discussed further in an issue of the journal Geophysical Research Letters [Kollmann et al. (2017), Geophys. Res. Lett., 44, 5259-5268].) Juno also has detected signatures of a population of high-energy, heavy ions in the inner edges of Jupiter's relativistic electron radiation belt. This radiation belt was previously understood to contain mostly electrons moving at near light speed. The signatures of the heavy ions are observed at high latitude locations within the electron belt -- a region not previously explored by spacecraft. The origin and exact species of these heavy ions is not yet understood. Juno's Stellar Reference Unit (SRU-1) star camera detects the signatures of this population as extremely high noise in images collected as part of the mission's radiation monitoring investigation. The locations where the heavy ions were detected are

Facts and Suggestions from a Brief History of the Galilean Moons and Space Weathering

NASA Astrophysics Data System (ADS)

Cooper, John

2010-05-01

From Galileo Galilei's Starry Messenger of four centuries ago we began the long journey of Galilean moon exploration now planned to continue with the joint ESA-NASA Europa Jupiter System Mission. Nearly eighty years after this historic beginning, the Keplerian orbital motions of these moons could be understood in terms of universal laws of motion and gravitation with Newton's Mathematical Principles of Natural Philosophy of 1687. But now looking back from the present to long before the discovery of magnetospheric radio emissions from Jupiter by Burke and Franklin in 1955 [1], we can infer the first apparent evidence for magnetospheric space weathering of the moon surfaces only from the 1926 first report of Stebbins [2] on photometric measurements of surface albedo light curves. These observations established the tidal locking of rotational and orbital motions from leading-trailing albedo asymmetries that we now significantly (if not entirely) associate with space weathering effects of the moon-magnetosphere-moon interactions. Of all the remote and in-situ observations that followed, those of the Pioneer (1973-1974), Voyager (1979), and Galileo (1995-2003) missions, and of the supporting measurements that followed in passing by the Ulysses (1992), Cassini (2000), and New Horizons (2007) missions, the discovery of greatest impact for space weathering may have been the first detection of Io volcanism by the Voyagers [3]. Accelerated as pickup ions in the corotating planetary magnetic field of Jupiter, atoms and molecules from the volcanic plume ejecta provide the primary source of magnetospheric ions for interactions with the other Galilean moons. These interactions include simple surface implantation of the iogenic ions, erosion of surface materials by ion sputtering, and modification of surface chemistry induced by volume ionization from more penetrating ions and electrons. From the highest energy magnetospheric protons and heavier ions, these interactions can be

Io, the closest Galileo's Medicean Moon: Changes in its Sodium Cloud Caused by Jupiter Eclipse

NASA Astrophysics Data System (ADS)

Grava, Cesare; Schneider, Nicholas M.; Barbieri, Cesare

2010-01-01

We report results of a study of true temporal variations in Io's sodium cloud before and after eclipse by Jupiter. The eclipse geometry is important because there is a hypothesis that the atmosphere partially condenses when the satellite enters the Jupiter's shadow, preventing sodium from being released to the cloud in the hours immediately after the reappearance. The challenge lies in disentangling true variations in sodium content from the changing strength of resonant scattering due Io's changing Doppler shift in the solar sodium absorption line. We undertook some observing runs at Telescopio Nazionale Galileo (TNG) at La Palma Canary Island with the high resolution spectrograph SARG in order to observe Io entering into Jupiter's shadow and coming out from it. The particular configuration chosen for the observations allowed us to observe Io far enough from Jupiter and to disentangle line-of-sight effects looking perpendicularly at the sodium cloud. We will present results which took advantage of a very careful reduction strategy. We remove the dependence from γ-factor, which is the fraction of solar light available for resonant scattering, in order to remove the dependence on the radial velocity of Io with respect to the Sun. This work has been supported by NSF's Planetary Astronomy Program, INAF/TNG and the Department of Astronomy and Cisas of University of Padova, through a contract by the Italian Space Agency ASI.

Using Simple Harmonic Motion to Follow the Galilean Moons--Testing Kepler's Third Law on a Small System

ERIC Educational Resources Information Center

de Moraes, I. G.; Pereira, J. A. M.

2009-01-01

The motion of the four Galilean moons of Jupiter is studied in this work. The moons had their positions with respect to the centre of the planet measured during one week of observation by means of telescopic charge coupled device images. It is shown that their movement can be well described as a simple harmonic motion. The revolution period and…

Plasma IMS Composition Measurements for Europa and the Other Galilean Moons

NASA Technical Reports Server (NTRS)

Sittler, Edward; Cooper, John; Hartle, Richard; Lipatov, Alexander; Mahaffy, Paul; Paterson, William; Pachalidis, Nick; Coplan, Mike; Cassidy, Tim

2010-01-01

NASA and ESA are planning the joint Europa Jupiter System Mission (EJSM) to the Jupiter system with specific emphasis to Europa and Ganymede, respectively. The Japanese Space Agency is also planning an orbiter mission to explore Jupiter's magnetosphere and the Galilean satellites. For NASA's Jupiter Europa Orbiter (JEO) we are developing the 3D Ion Mass Spectrometer (IMS) with two main goals which can also be applied to the other Galilean moons, 1) measure the plasma interaction between Europa and Jupiter's magnetosphere and 2) infer the 4 pi surface composition to trace elemental and significant isotopic levels. The first goal supports the magnetometer (MAG) measurements, primarily directed at detection of Europa's sub-surface ocean, while the second gives information about transfer of material between the Galilean moons, and between the moon surfaces and subsurface layers putatively including oceans. The measurement of the interactions for all the Galilean moons can be used to trace the in situ ion measurements of pickup ions back to either Europa's or Ganymede's surface from the respectively orbiting spacecraft. The IMS instrument, being developed under NASA's Astrobiology Instrument Development Program, would maximally achieve plasma measurement requirements for JEO and EJSM while moving forward our knowledge of Jupiter system composition and source processes to far higher levels than previously envisaged. The composition of the global surfaces of Europa and Ganymede can be inferred from the measurement of ejected neutrals and pick-up ions using at minimum an in situ payload including MAG and IMS also fully capable of meeting Level 1 mission requirements for ocean detection and survey. Elemental and isotopic analysis of potentially extruded oceanic materials at the moon surfaces would further support the ocean objectives. These measurements should be made from a polar orbiting spacecraft about Europa or Ganymede at height 100 km. The ejecta produced by

Origin of the terrestrial planets and the moon.

PubMed

Taylor, S R

1996-03-01

Our ideas about the origin and evolution of the solar system have advanced significantly as a result of the past 25 years of space exploration. Metal-sulfide-silicate partitioning seems to have been present in the early dust components of the solar nebula, prior to chondrule formation. The inner solar nebula was depleted in volatile elements by early solar activity. The early formation of the gas giant, Jupiter, affected the subsequent development of inner solar system and is responsible for the existence of the asteroid belt, and the small size of Mars. The Earth and the other terrestrial planets accreted in a gas-free environment, mostly from volatile-depleted planetesimals which were already differentiated into metallic cores and silicate mantles. The origin of the Moon by a single massive impact with a body larger than Mars explains the angular momentum, orbital characteristics and unique nature of the Earth-Moon system. The density and chemical differences between the Earth and Moon are accounted for by deriving the Moon from the mantle of the impactor.

Compositional Mapping of Planetary moons by Mass Spectrometry of Dust Ejecta

NASA Astrophysics Data System (ADS)

Postberg, F.; Gruen, E.; Horanyi, M.; Kempf, S.; Krüger, H.; Schmidt, J.; Spahn, F.; Srama, R.; Sternovsky, Z.; Trieloff, M.

2011-12-01

Classical methods to analyze the surface composition of planetary objects from a space craft are IR and gamma ray spectroscopy and neutron backscatter measurements. We present a complementary method to analyze rocky or icy dust particles as samples of planetary objects from where they were ejected. Such particles, generated by the ambient meteoroid bombardment that erodes the surface, are naturally present on all atmosphereless moons and planets - they are enshrouded in clouds of ballistic dust particles. In situ mass spectroscopic analysis of these grains impacting on to a detector on a spacecraft reveals their composition as characteristic samples of planetary surfaces at flybys or from an orbiter. The well established approach of dust detection by impact ionization has recently shown its capabilities by analyzing ice particles expelled by subsurface salt water on Saturn's moon Enceladus. Applying the method on micro-meteoroid ejecta of less active moons would allow for the qualitative and quantitative analysis of a huge number of samples from various surface areas, thus combining the advantages of remote sensing and a lander. Utilizing the heritage of the dust detectors onboard Ghiotto, Ulysses, Galileo, and Cassini a variety of improved, low-mass lab-models have been build and tested. They allow the chemical characterization of ice and dust particles encountered at speeds as low as 1 km/s and an accurate reconstruction of their trajectories. Depending on the sampling altitude, a dust trajectory sensor can trace back the origin of each analyzed grain with about 10 km accuracy at the surface. Since achievable detection rates are on the order of thousand per orbit, an orbiter can create a compositional map of samples taken from a greater part of the surface. Flybies allow an investigation of certain surface areas of interest. Dust impact velocities are in general sufficiently high for impact ionization at orbiters about planetary objects with a radius of at least

Photographer : JPL Range : 4.2 million kilometers (2.6 million miles) Ganymede is Jupiter's Largest

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 4.2 million kilometers (2.6 million miles) Ganymede is Jupiter's Largest Galilean satellites and 3rd from the planet. Photo taken after midnight Ganymede is slightly larger than Mercury but much less dense (twice the density of water). Its surface brightness is 4 times of Earth's Moon. Mare regions (dark features) are like the Moon's but have twice the brightness, and believed to be unlikely of rock or lava as the Moon's are. It's north pole seems covered with brighter material and may be water frost. Scattered brighter spots may be related to impact craters or source of fresh ice.

Tides and the Biosphere of Europa

NASA Astrophysics Data System (ADS)

Greenberg, Richard

2002-01-01

It's been suspected for at least a decade now that Jupiter's icy moon Europa harbors a global ocean of liquid water beneath its crust. To many scientists the presence of another ocean in our solar system immediately conjured up images of extraterrestrial lifeforms swimming in an alien sea. But what sorts of life could evolve in the dark waters of a subsurface ocean, and how would it derive the energy it needs to survive? Planetary scientist, Richard Greenberg has been studying the surface features of Europa, and he finds that the icy crust that covers the ocean may not be as thick as scientists had at first supposed. Cracks in Europa's surface suggest that the ocean waters may come very close to the surface. If so, the cracks themselves may provide a niche for life, and the light near the surface of the moon could provide energy for photosynthetic organisms.

Moon - North Polar Mosaic, Color

NASA Technical Reports Server (NTRS)

1996-01-01

During its flight, the Galileo spacecraft returned images of the Moon. The Galileo spacecraft surveyed the Moon on December 7, 1992, on its way to explore the Jupiter system in 1995-1997. The left part of this north pole view is visible from Earth. This color picture is a mosaic assembled from 18 images taken by Galileo's imaging system through a green filter. The left part of this picture shows the dark, lava-filled Mare Imbrium (upper left); Mare Serenitatis (middle left), Mare Tranquillitatis (lower left), and Mare Crisium, the dark circular feature toward the bottom of the mosaic. Also visible in this view are the dark lava plains of the Marginis and Smythii Basins at the lower right. The Humboldtianum Basin, a 650-kilometer (400-mile) impact structure partly filled with dark volcanic deposits, is seen at the center of the image. The Moon's north pole is located just inside the shadow zone, about a third of the way from the top left of the illuminated region. The Galileo project is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory.

Surface evolution of two-component stone/ice bodies in the Jupiter region

NASA Astrophysics Data System (ADS)

Hartmann, W. K.

1980-11-01

Observational and theoretical data converge on the conclusion that planetesimals in Jupiter's region of the solar nebula were initially composed predominantly of a mixture of roughly 39-70% H2O ice by volume, and 30-61% dark stony material resembling carbonaceous chondrites. Recent observations emphasize a division of most asteroid and satellite surfaces in this region into two distinct groups: bright icy material and dark stony material. The present model accounts for these by two main processes: an impact-induced buildup of a dark stony regolith in the absence of surface thermal disturbance, and thermal-disturbance-induced eruption of 'water magmas' that create icy surfaces. 'Thermal disturbances' include tidal and radiative effects caused by nearness of a planet. A correlation of crater density and albedo, Ganymede's dark-ray craters, and other observed phenomena (listed in the summary) appear consistent with the model discussed here.

Trade-off between TMA and RC configurations for JANUS camera

NASA Astrophysics Data System (ADS)

Greggio, D.; Magrin, D.; Munari, M.; Paolinetti, R.; Turella, A.; Zusi, M.; Cremonese, G.; Debei, S.; Della Corte, V.; Friso, E.; Hoffmann, H.; Jaumann, R.; Michaelis, H.; Mugnuolo, R.; Olivieri, A.; Palumbo, P.; Ragazzoni, R.; Schmitz, N.

2016-07-01

JANUS (Jovis Amorum Ac Natorum Undique Scrutator) is a high-resolution visible camera designed for the ESA space mission JUICE (Jupiter Icy moons Explorer). The main scientific goal of JANUS is to observe the surface of the Jupiter satellites Ganymede and Europa in order to characterize their physical and geological properties. During the design phases, we have proposed two possible optical configurations: a Three Mirror Anastigmat (TMA) and a Ritchey-Chrétien (RC) both matching the performance requirements. Here we describe the two optical solutions and compare their performance both in terms of achieved optical quality, sensitivity to misalignment and stray light performances.

A Physical Model of the Proton Radiation Belts of Jupiter inside Europa's Orbit

NASA Astrophysics Data System (ADS)

Nénon, Q.; Sicard, A.; Kollmann, P.; Garrett, H. B.; Sauer, S. P. A.; Paranicas, C.

2018-05-01

A physical model of the Jovian trapped protons with kinetic energies higher than 1 MeV inward of the orbit of the icy moon Europa is presented. The model, named Salammbô, takes into account the radial diffusion process, the absorption effect of the Jovian moons, and the Coulomb collisions and charge exchanges with the cold plasma and neutral populations of the inner Jovian magnetosphere. Preliminary modeling of the wave-particle interaction with electromagnetic ion cyclotron waves near the moon Io is also performed. Salammbô is validated against in situ proton measurements of Pioneer 10, Pioneer 11, Voyager 1, Galileo Probe, and Galileo Orbiter. A prominent feature of the MeV proton intensity distribution in the modeled area is the 2 orders of magnitude flux depletion observed in MeV measurements near the orbit of Io. Our simulations reveal that this is not due to direct interactions with the moon or its neutral environment but results from scattering of the protons by electromagnetic ion cyclotron waves.

NASA's Proposed Budget Sees Small Dip, Emphasizes Innovation and Autonomy in Space

NASA Astrophysics Data System (ADS)

Kumar, Mohi

2014-03-01

NASA's proposed federal budget for fiscal year (FY) 2015, released on 4 March, includes new plans to send a probe to Jupiter's icy moon Europa, a ramp up in funding for a mission to redirect an asteroid into near-Earth orbit, funds to extend the life of the International Space Station (ISS) by at least a decade, and plans to return to the United States the capability to launch astronauts into space, among other highlights.

Moon-Magnetosphere Interactions at Saturn: Recent Highlights from Cassini Observations and Modelling

NASA Astrophysics Data System (ADS)

Simon, S.; Kriegel, H.; Saur, J.; Neubauer, F. M.; Wennmacher, A.; Motschmann, U.; Dougherty, M. K.

2012-09-01

Since the arrival of the Cassini spacecraft at Saturn in July 2004, newly collected plasma and magnetic field data have greatly expanded our knowledge on the giant planet's magnetosphere and its multifaceted family of moons. More than 160 orbits around the planet have already been accomplished by Cassini, encompassing 85 close flybys of Saturn's largest satellite Titan as well as 20 encounters of Enceladus. This small icy moon had been identified as the major source of magnetospheric plasma and neutral particles during the first year of Cassini's tour in the Saturnian system. In addition, the spacecraft has paid visits to several of the other icy satellites in the inner and middle magnetosphere: Rhea (3 flybys), Dione (3 flybys) and Tethys (1 flyby). The inner icy satellites and Titan are located within Saturn's magnetosphere for average solar wind conditions, revolving around the giant planet on prograde orbits in its equatorial plane. Since their orbital velocities are clearly exceeded by the speed of the at least partially corotating magnetospheric plasma, the moons are continuously "overtaken" by the magnetospheric flow. Thus, their trailing hemispheres are permanently exposed to a bombardment with thermal magnetospheric plasma. The characteristics of the resulting plasma interaction process depend on the properties of the moon itself as well as on the parameters (density, velocity, temperature, magnetic field strength) of the incident magnetospheric flow and the energetic particle population. In this presentation, we shall review some recent advances in our understanding of the interaction between Saturn's moons and their plasma environment: Enceladus: Electron absorption by submicron dust grains within the plume gives rise to a negative sign of the Hall conductance in Enceladus' plume. The resulting twist of the magnetic field, referred to as the Anti-Hall effect, has been observed during all targeted Enceladus flybys accomplished to date. We present an

Compositions of Oceans on Icy Solar System Bodies (Invited)

NASA Astrophysics Data System (ADS)

Zolotov, M. Y.

2010-12-01

Interior oceans may exist on at least several solar system bodies: Europa, Enceladus, Ganymede, Titan and Triton. Compositions of the oceans could reflect bulk chemistries on the bodies, degree and timing of differendentition, current temperature and pressure conditions, and chemical exchanges between icy shells, liquid layers, and suboceanic solids (rocks, sediments, ices and clathrates). Observational signs are sparse and modeling is the major approach to evaluate oceanic compositions. On Europa, a presence of S(VI) species and CO2 at endogenic surface features [1] suggests sulfates and C species (organic and/or inorganic) in the ocean. The detection of NaCl and Na2CO3/NaHCO3-bearing grains emitted from Enceladus [2] implies the dominance of Na, Cl and carbonate/bicarbonate ions in the past and/or present alkaline fluids in the interior. These observations are consistent with independent models for water-rock interaction [3]. Evaluated low contents of other elements (Mg, Fe, Ca, K, S, P, etc.) in initial oceanic waters [3] are accounted for by low solubilities of minerals deposited from water solutions (serpentine, saponite, magnetite, carbonates, sulfides and phosphates). Oceanic redox states are affected by the composition of accreted ices and rocks, hydrogen production through oxidation of solids (mainly Fe-Ni metal) by water and an efficiency of H2 escape. Formation of a sulfate-bearing ocean (as on Europa) through oxidation of sulfides could have been driven by radiolytically-formed oxidants (H2O2, O2), high-temperature (>500 K) hydrothermal activity and H2 escape. Formation of sulfate facilitates leaching of Mg from minerals leading to the Mg-SO4-Na-Cl ocean. Although some of these factors could have played roles on the Galilean satellites, formation of sulfate-bearing oceans beyond Jupiter is unlikely. Accretion of cometary-type ices on moons allows an existence of water-methanol-ammonia liquids at ~153 K, although ammonia could have been sequestered in

Development and Testing of a Laser-Powered Cryobot for Outer Planet Icy Moon Exploration

NASA Astrophysics Data System (ADS)

Siegel, V.; Stone, W.; Hogan, B.; Lelievre, S.; Flesher, C.

2013-12-01

Project VALKYRIE (Very-deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice Explorer) is a NASA-funded effort to develop the first laser powered cryobot - a self-contained intelligent ice penetrator capable of delivering science payloads through ice caps of the outer planet icy moons. The long range objective is to enable a full-scale Europa lander mission in which an autonomous life-searching underwater vehicle is transported by the cryobot and launched into the sub-surface Europan ocean. Mission readiness testing will involve an Antarctic sub-glacial lake cryobot sample return through kilometers of ice cap thickness. A key element of VALKYRIE's design is the use of a high energy laser as the primary power source. 1070 nm laser light is transmitted at a power level of 5 kW from a surface-based laser and injected into a custom-designed optical waveguide that is spooled out from the descending cryobot. Light exits the downstream end of the fiber, travels through diverging optics, and strikes a beam dump, which channels thermal power to hot water jets that melt the descent hole. Some beam energy is converted, via photovoltaic cells, to electricity for running onboard electronics and jet pumps. Since the vehicle can be sterilized prior to deployment and the melt path freezes behind it, preventing forward contamination, expansions on VALKYRIE concepts may enable cleaner and faster access to sub-glacial Antarctic lakes. Testing at Stone Aerospace between 2010 and 2013 has already demonstrated high power optical energy transfer over relevant (kilometer scale) distances as well as the feasibility of a vehicle-deployed optical waveguide (through which the power is transferred). The test vehicle is equipped with a forward-looking synthetic aperture radar (SAR) that can detect obstacles out to 1 kilometer from the vehicle. The initial ASTEP test vehicle will carry a science payload consisting of a DUV flow cytometer and a water sampling sub-system that will be

Galileo infrared imaging spectrometry measurements at the Moon

NASA Technical Reports Server (NTRS)

Mccord, Thomas B.; Soderblom, Larry A.; Carlson, Robert W.; Fanale, Fraser P.; Lopes-Gautier, Rosaly; Ocampo, Adriano; Forsythe, Jennifer; Campbell, Bruce; Granahan, James C.; Smythe, W. D.

1994-01-01

Imaging spectrometer observations were made of the surface of the Moon during the December 1990 flyby of the Earth-Moon system by the Galileo spacecraft. This article documents this data set and presents analyses of some of the data. The near infrared mapping spectrometer (NIMS) investigation obtained 17 separate mosaics of the Moon in 408 spectral channels between about 0.7 and 5.2 micrometers. The instrument was originally designed to operate in orbit about Jupiter and therefore saturates at many spectral channels for most measurement situations at 1 AU. However, sufficient measurements were made of the Moon to verify the proper operation of the instrument and to demonstrate its capabilities. Analysis of these data show that the NIMS worked as expected and produced measurements consistent with previous ground-based telescopic studies. These are the first imaging spectrometer measurements of this type from space for the Moon, and they illustrate several major points concerning this type of observation and about the NIMS capabilities specifically. Of major importance are the difference between framing and scanning instruments and the effects of the spacecraft and the scan platform on the performance of such and experiment. The science return of subsequent NIMS and other investigation measurements will be significantly enhanced by the experience and results gained.

Unraveling the Reaction Chemistry of Icy Ocean World Surfaces

NASA Astrophysics Data System (ADS)

Hudson, R.; Loeffler, M. J.; Gerakines, P.

2017-12-01

The diverse endogenic chemistry of ocean worlds can be divided among interior, surface, and above-surface process, with contributions from exogenic agents such as solar, cosmic, and magnetospheric radiation. Bombardment from micrometeorites to comets also can influence chemistry by both delivering new materials and altering pre-existing ones, and providing energy to drive reactions. Geological processes further complicate the chemistry by transporting materials from one environment to another. In this presentation the focus will be on some of the thermally driven and radiation-induced changes expected from icy materials, primarily covalent and ionic compounds. Low-temperature conversions of a few relatively simple molecules into ions possessing distinct infrared (IR) features will be covered, with an emphasis on such features as might be identified through either orbiting spacecraft or landers. The low-temperature degradation of a few bioorganic molecules, such as DNA nucleobases and some common amino acids, will be used as examples of the more complex, and potentially misleading, chemistry expected for icy moons of the outer solar system. This work was supported by NASA's Emerging Worlds and Outer Planets Research programs, as well as the NASA Astrobiology Institute's Goddard Center for Astrobiology.

Photographer : JPL Range : 5.9 million kilometers (3.66 million miles) Europa is Jupiter's 2nd

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 5.9 million kilometers (3.66 million miles) Europa is Jupiter's 2nd Galilean satellite from the planet. Photo taken early morning and through a violet filter. Faint swirls and Linear Patterns show in the equarorial region(which is darker than the poles). The hemisphere shown always faces Jupiter. North is up. Europa is the brightest of the Galilian satellites but shows low contrast on this hemisphere. Density and size is similar to Earth's Moon. Indications of water ice or ground water on surface is shown

Radiation analysis for manned missions to the Jupiter system

NASA Technical Reports Server (NTRS)

De Angelis, G.; Clowdsley, M. S.; Nealy, J. E.; Tripathi, R. K.; Wilson, J. W.

2004-01-01

An analysis for manned missions targeted to the Jovian system has been performed in the framework of the NASA RASC (Revolutionary Aerospace Systems Concepts) program on Human Exploration beyond Mars. The missions were targeted to the Jupiter satellite Callisto. The mission analysis has been divided into three main phases, namely the interplanetary cruise, the Jupiter orbital insertion, and the surface landing and exploration phases. The interplanetary phase is based on departure from the Earth-Moon L1 point. Interplanetary trajectories based on the use of different propulsion systems have been considered, with resulting overall cruise phase duration varying between two and five years. The Jupiter-approach and the orbital insertion trajectories are considered in detail, with the spacecraft crossing the Jupiter radiation belts and staying around the landing target. In the surface exploration phase the stay on the Callisto surface is considered. The satellite surface composition has been modeled based on the most recent results from the GALILEO spacecraft. In the transport computations the surface backscattering has been duly taken into account. Particle transport has been performed with the HZETRN heavy ion code for hadrons and with an in-house developed transport code for electrons and bremsstrahlung photons. The obtained doses have been compared to dose exposure limits. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

Radiation analysis for manned missions to the Jupiter system.

PubMed

De Angelis, G; Clowdsley, M S; Nealy, J E; Tripathi, R K; Wilson, J W

2004-01-01

An analysis for manned missions targeted to the Jovian system has been performed in the framework of the NASA RASC (Revolutionary Aerospace Systems Concepts) program on Human Exploration beyond Mars. The missions were targeted to the Jupiter satellite Callisto. The mission analysis has been divided into three main phases, namely the interplanetary cruise, the Jupiter orbital insertion, and the surface landing and exploration phases. The interplanetary phase is based on departure from the Earth-Moon L1 point. Interplanetary trajectories based on the use of different propulsion systems have been considered, with resulting overall cruise phase duration varying between two and five years. The Jupiter-approach and the orbital insertion trajectories are considered in detail, with the spacecraft crossing the Jupiter radiation belts and staying around the landing target. In the surface exploration phase the stay on the Callisto surface is considered. The satellite surface composition has been modeled based on the most recent results from the GALILEO spacecraft. In the transport computations the surface backscattering has been duly taken into account. Particle transport has been performed with the HZETRN heavy ion code for hadrons and with an in-house developed transport code for electrons and bremsstrahlung photons. The obtained doses have been compared to dose exposure limits. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

JunoCam's Imaging of Jupiter

NASA Astrophysics Data System (ADS)

Orton, Glenn; Hansen, Candice; Momary, Thomas; Caplinger, Michael; Ravine, Michael; Atreya, Sushil; Ingersoll, Andrew; Bolton, Scott; Rogers, John; Eichstaedt, Gerald

2017-04-01

Juno's visible imager, JunoCam, is a wide-angle camera (58° field of view) with 4 color filters: red, green and blue (RGB) and methane at 889 nm, designed for optimal imaging of Jupiter's poles. Juno's elliptical polar orbit offers unique views of Jupiter's polar regions with spatial scales as good as 50 km/pixel. At closest approach ("perijove") the images have spatial scale down to ˜3 km/pixel. As a push-frame imager on a rotating spacecraft, JunoCam uses time-delayed integration to take advantage of the spacecraft spin to extend integration time to increase signal. Images of Jupiter's poles reveal a largely uncharted region of Jupiter, as nearly all earlier spacecraft except Pioneer 11 have orbited or flown by close to the equatorial plane. Poleward of 64-68° planetocentric latitude, Jupiter's familiar east-west banded structure breaks down. Several types of discrete features appear on a darker, bluish-cast background. Clusters of circular cyclonic spirals are found immediately around the north and south poles. Oval-shaped features are also present, ranging in size down to JunoCam's resolution limits. The largest and brightest features usually have chaotic shapes; animations over ˜1 hour can reveal cyclonic motion in them. Narrow linear features traverse tens of degrees of longitude and are not confined in latitude. JunoCam also detected optically thin clouds or hazes that are illuminated beyond the nightside ˜1-bar terminator; one of these detected at Perijove lay some 3 scale heights above the main cloud deck. Tests have been made to detect the aurora and lightning. Most close-up images of Jupiter have been acquired at lower latitudes within 2 hours of closest approach. These images aid in understanding the data collected by other instruments on Juno that probe deeper in the atmosphere. When Jupiter was too close to the sun for ground-based observers to collect data between perijoves 1 and 2, JunoCam took a sequence of routine images to monitor large

Galileo to Jupiter: Probing the Planet and Mapping Its Moons

NASA Technical Reports Server (NTRS)

1979-01-01

The first project to use the space shuttle as an interplanetary launch vehicle, the Galileo mission is designed to obtain information about the origin and evolution of the solar system by studying large-scale phenomena on Jupiter and its satellites. Aimed towards Mars to obtain gravity assist, the orbiting spacecraft will deploy a probe, which penetrating the Jovian atmosphere, will transmit data for approximately an hour. The spacecraft itself will inspect the atmospheres, ionospheres, and surfaces of Ganymede, Io, Europa, and Callisto, as well as determine their magnetic and gravitational properties. The experiments to be conducted and their scientific objectives are described. Known facts about the Jovian system are reviewed.

Jupiter Hot Spot Makes Trouble For Theory

NASA Astrophysics Data System (ADS)

2002-02-01

A pulsating hot spot of X-rays has been discovered in the polar regions of Jupiter's upper atmosphere by NASA's Chandra X-ray Observatory. Previous theories cannot explain either the pulsations or the location of the hot spot, prompting scientists to search for a new process to produce Jupiter's X-rays. "The location of the X-ray hot spot effectively retires the existing explanation for Jupiter's X-ray emission, leaving us very unsure of its origin," said Randy Gladstone, of the Southwest Research Institute in San Antonio and lead author of a paper on the results in the Feb.28, 2002 issue of the journal Nature. "The source of ions that produce the X-rays must be a lot farther away from Jupiter than previously believed." Chandra observed Jupiter for 10 hours on Dec. 18, 2000, when NASA's Cassini spacecraft was flying by Jupiter on its way to Saturn. The X-ray observations revealed that most of the auroral X-rays come from a pulsating hot spot that appears at a fixed location near the north magnetic pole of Jupiter. Bright infrared and ultraviolet emissions have also been detected from this region in the past. The X-rays were observed to pulsate with a period of 45 minutes, similar to the period of high-latitude radio pulsations detected by NASA's Galileo and Cassini spacecraft. Jupiter X-ray/UV/Optical Composite Credit: X-ray: NASA/SWRI/R.Gladstone et al. UV: NASA/HST/J.Clarke et al. Optical: NASA/HST/R.Beebe et al. An aurora of X-ray light near Jupiter's polar regions had been detected by previous satellites. However, scientists were unable to determine the exact location of the X-rays. The accepted theory held that the X-rays were produced by energetic oxygen and sulfur ions that became excited as they ran into hydrogen and helium in Jupiter's atmosphere. Oxygen and sulfur ions (originally from Jupiter's moon Io) are energized while circulating around Jupiter's enormous magnetosphere. And, some - the purported X-ray producers - get dumped into Jupiter's atmosphere

2:30 pm Photographer : JPL Range : 2.6 million km. ( 1.6 million miles ) Ganymede is Jupiter's

NASA Technical Reports Server (NTRS)

1979-01-01

2:30 pm Photographer : JPL Range : 2.6 million km. ( 1.6 million miles ) Ganymede is Jupiter's largest satellite ( or moon ) With a radius of about 2600 km., about 1.5 times that of our moon, Ganymede has a bulk density of about 2.0 g/cc, almost half that of our moon, and is probably composed of rock and ice. The large dark regions, in the northeast quadrant, and the white spots, resemble features found on the moon, mare and impact respectively. The long white filaments resemble rays associated with impacts on the lunar surface. The various colors, other than the several blue, green, & orange dots, which are markings on the camera used for pointing determinations and are not physical markings, probably represent differing surface materials.

Various Landscapes and Features on Europa

NASA Technical Reports Server (NTRS)

1997-01-01

These 15 frames show the great variety of surface features on Jupiter's icy moon, Europa, which have been revealed by the Galileo spacecraft Solid State Imaging (CCD) system during its first six orbits around Jupiter from June 1996 to February 1997. North is to the top of each of the images. The features seen on Europa's surface document both internal and external processes shaping the icy crust. Internal processes and the possible presence of liquid water beneath the ice are indicated by features such as 'dark spots', lobe-shaped flow features, 'puddles','mottled terrain', knobs, pits, and the darker areas along ridges and triple bands.

Europa is subjected to constant tugging from the giant planet, Jupiter, as well as from its neighboring moons, Io and Ganymede. This causes 'tidal' forces that affect Europa's interior and surface. Evidence for such forces includes ridges, fractures, wedge-shaped bands, and areas of 'chaos'. Some of these features result from alternate extension and compression buckling and pulling apart Europa's icy shell.

Impact craters document external effects on a planet's surface. Although present on Europa, impact craters are relatively scarce compared to the number seen on Ganymede, Callisto, and on the surfaces of most other 'rocky' planets and moons in our solar system. This scarcity of craters suggests that the surface of Europa is very young. 'Maculae' on Europa may be the scars from large impact events.

These images have resolutions from 27 meters (89 feet) to 7 kilometers (4.3 miles) per picture element (pixel) and were taken by Galileo at ranges of 2,500 kilometers (1,525 miles) to 677,000 kilometers (413,000 miles) from Europa.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web

Mass spectrometry of planetary exospheres at high relative velocity: direct comparison of open- and closed source measurements

NASA Astrophysics Data System (ADS)

Meyer, Stefan; Tulej, Marek; Wurz, Peter

2016-04-01

The exploration of habitable worlds around the gas giants in the Solar System is of major interest in upcoming planetary missions. Exactly this theme is addressed by the Jupiter Icy Moons Explorer (JUICE) mission of ESA, which will characterise Ganymede, Europa and Callisto as planetary objects and potential habitats [1], [2]. We developed a prototype of the Neutral gas and Ion Mass spectrometer (NIM) of the Particle Environment Package (PEP) for the JUICE mission intended for composition measurements of neutral gas and thermal plasma. NIM/PEP will be used to measure the chemical composition of the exospheres of the icy Jovian moons. Besides direct ion measurement, the NIM instrument is able to measure the inflowing neutral gas in two different modes: in neutral mode the gas enters directly the ion source (open source) and in thermal mode, the gas gets thermally accommodated to wall temperature by several collisions inside an equilibrium sphere before entering the ion source (closed source). We performed measurements with the prototype NIM using a neutral gas beam of 1 up to 5 km/s velocity in the neutral and thermal mode. The current trajectory of JUICE foresees a flyby velocity of 4 km/s at Europa, other flybys are in the range of 1 up to 7 km/s and velocity in Ganymede orbits is around 2 km/s. Different species are used for gas beam, such as noble gases Ne, Ar, Kr as well as molecules like H2, Methane, Ethane, Propane and more complex ones. We will present the results of these measurements with respect to fragmentation and density enhancements in the closed source mode. Furthermore, we will give a direct comparison between open and closed source mode measurements. References: [1] ESA, "JUICE assessment study report (Yellow Book)", ESA/SRE(2011)18, 2012. [2] O. Grasset, M.K. Dougherty, A. Coustenis, E.J. Bunce, C. Erd, D. Titov, M. Blanc, A. Coates, P. Drossart, L.N. Fletcher, H. Hussmann, R. Jaumann, N. Krupp, J.-P. Lebreton, O. Prieto-Ballesteros, P. Tortora, F

Flow and fracture of ices, with application to icy satellites (Invited)

NASA Astrophysics Data System (ADS)

Durham, W. B.; Stern, L. A.; Pathare, A.; Golding, N.

2013-12-01

large icy moons; flow of very low melting temperature, weakly bonded solids such as N2, CH4, and CO2; and the behavior of ice-rich, large exoplanets. We will review recent results on the rheological behavior of water ice I in the regime of combined flow by grain size sensitive and grain size insensitive mechanisms of deformation, and in particular the possibility that grain size is not a free variable when ice I deforms over large strains for long periods of time, but rather is defined by stress and temperature. Existing rheological laws suggest that viscosity of an ice-I-rich outer layer on a large icy moon, including a moon as small as Enceladus, may be strongly grain size dependent. We will also review developments in two-phase flow, with implications for geysers on Enceladus and methane in Titan's atmosphere.

Comparison of high-energy trapped particle environments at the Earth and Jupiter.

PubMed

Jun, Insoo; Garrett, Henry B

2005-01-01

The 'Van Allen belts' of the trapped energetic particles in the Earth's magnetosphere were discovered by the Explorer I satellite in 1958. In addition, in 1959, it was observed that UHF radio emissions from Jupiter probably had a similar source--the Jovian radiation belts. In this paper, the global characteristics of these two planets' trapped radiation environments and respective magnetospheres are compared and state-of-the-art models used to generate estimates of the high-energy electron (> or = 100 keV) and proton (> or = 1 MeV) populations--the dominant radiation particles in these environments. The models used are the AP8/AE8 series for the Earth and the Divine-Garrett/GIRE model for Jupiter. To illustrate the relative magnitude of radiation effects at each planet, radiation transport calculations were performed to compute the total ionising dose levels at the geosynchronous orbit for the Earth and at Europa (Jupiter's 4th largest moon) for Jupiter. The results show that the dose rates are -0.1 krad(Si) d(-1) at the geosynchronous orbit and -30 krad(Si) d((-1) at Europa for a 2.5 mm spherical shell aluminium shield--a factor of -300 between the two planets.

Hubble Spies Spooky Shadow on Jupiter's Giant Eye

NASA Image and Video Library

2014-10-28

This trick that the planet is looking back at you is actually a Hubble treat: An eerie, close-up view of Jupiter, the biggest planet in our solar system. Hubble was monitoring changes in Jupiter’s immense Great Red Spot (GRS) storm on April 21, 2014, when the shadow of the Jovian moon, Ganymede, swept across the center of the storm. This gave the giant planet the uncanny appearance of having a pupil in the center of a 10,000 mile-diameter “eye.” For a moment, Jupiter “stared” back at Hubble like a one-eyed giant Cyclops. Credit: NASA, ESA, and A. Simon (Goddard Space Flight Center) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

The Irregular Moons of Saturn

NASA Astrophysics Data System (ADS)

Denk, Tilmann; Mottola, Stefano; Tosi, Federico; Bottke, William; Hamilton, Douglas P.

2017-10-01

The 38 irregular moons of Saturn, all but Phoebe discovered between 2000 and 2007, outnumber the planet's classical satellites. Observations from the ground and from near-Earth space have revealed orbits, sizes, and colors and have hinted at the existence of dynamical families, indicative of collisional evolution and common progenitors. More recently, remote observations of many irregular satellites with the Cassini spacecraft produced lightcurves that helped determine rotational periods, coarse shape models, potential hemispheric color heterogeneities, and other basic properties.From Cassini, a total of 25 Saturnian irregulars have been observed with the ISS camera. Their rotational periods range from 5.45 h to 76.13 h. The absence of fast rotators is evident. Among main-belt asteroids of the same size range (~4 to ~45 km), one third of the objects have faster rotations, indicating that many irregulars should be low-density objects.While the origin of the irregulars is still debated, capture of comets via three-body interactions during giant planets encounters does the best job thus far at reproducing the observed prograde/retrograde orbits. Data from the ground, near-Earth spacecraft, and Cassini as well as modeling results suggest the population visible today has experienced substantial collisional evolution. It may be that only Phoebe has survived relatively intact. The small particle debris drifts toward Saturn by P-R drag, with most of it swept up by Titan. Only remnants of this process are visible today.Our current knowledge on the Saturnian irregulars will be summarized in a chapter [1] in the book "Enceladus and the Icy Moons of Saturn" [2]. The talk will give an overview on the chapter's content, which covers the following topics: Orbital "architecture" (a,e,i), sizes and colors, Cassini observations and results, Phoebe, origin, an outlook.[1] Denk, T., Mottola, S., Tosi, F., Bottke, W.F., Hamilton, D.P. (2018): The Irregular Satellites of Saturn. In

Water and the Interior Structure of Terrestrial Planets and Icy Bodies

NASA Astrophysics Data System (ADS)

Monteux, J.; Golabek, G. J.; Rubie, D. C.; Tobie, G.; Young, E. D.

2018-02-01

Water content and the internal evolution of terrestrial planets and icy bodies are closely linked. The distribution of water in planetary systems is controlled by the temperature structure in the protoplanetary disk and dynamics and migration of planetesimals and planetary embryos. This results in the formation of planetesimals and planetary embryos with a great variety of compositions, water contents and degrees of oxidation. The internal evolution and especially the formation time of planetesimals relative to the timescale of radiogenic heating by short-lived 26Al decay may govern the amount of hydrous silicates and leftover rock-ice mixtures available in the late stages of their evolution. In turn, water content may affect the early internal evolution of the planetesimals and in particular metal-silicate separation processes. Moreover, water content may contribute to an increase of oxygen fugacity and thus affect the concentrations of siderophile elements within the silicate reservoirs of Solar System objects. Finally, the water content strongly influences the differentiation rate of the icy moons, controls their internal evolution and governs the alteration processes occurring in their deep interiors.

NASA Reveals New Discoveries on Oceans Beyond Earth During Science Briefing

NASA Image and Video Library

2017-04-13

During a NASA science briefing on April 13, representatives from the agency discussed new results about ocean worlds in our solar system based on data gathered by NASA’s Cassini spacecraft and the Hubble Space Telescope. The two veteran missions are providing tantalizing new details about icy, ocean-bearing moons of Jupiter and Saturn, further enhancing the scientific interest of these and other "ocean worlds" in our solar system and beyond. New research from Cassini indicates that hydrogen gas, which could potentially provide a chemical energy source for life, is pouring into the ocean of Saturn's icy moon Enceladus from hydrothermal vents in the seafloor. The Cassini spacecraft detected the hydrogen in the plume of gas and icy material spraying from Enceladus during its deepest dive through the plume on Oct. 28, 2015.This means that ocean microbes -- if any exist there -- could use the hydrogen to produce energy NASA’s Hubble Space Telescope saw a probable plume of material erupting from the moon’s surface on 2016, at the same location where Hubble saw evidence of a plume in 2014. These images bolster evidence that the Europa plumes could be a real phenomenon, flaring up intermittently in the same region on the moon's surface. Both Cassini and Hubble investigations are laying the groundwork for NASA's Europa Clipper mission, which is being planned for launch in the 2020s.

Chandra Probes High-Voltage Auroras on Jupiter

NASA Astrophysics Data System (ADS)

2005-03-01

auroras. Jupiter's rapid rotation, intense magnetic field, and an abundant source of particles from its volcanically active moon, Io, create a huge reservoir of electrons and ions. These charged particles, trapped in Jupiter's magnetic field, are continually accelerated down into the atmosphere above the polar regions where they collide with gases to produce the aurora, which are almost always active on Jupiter. If the particles responsible for the aurora came from the Sun, they should have been accompanied by large number of protons, which would have produced an intense ultraviolet aurora. Hubble ultraviolet observations made during the Chandra monitoring period showed relatively weak ultraviolet flaring. The combined Chandra and Hubble data indicate that this auroral activity was caused by the acceleration of charged ions of oxygen and other elements trapped in the polar magnetic field high above Jupiter's atmosphere. Hubble Ultraviolet Image of Jupiter Hubble Ultraviolet Image of Jupiter Chandra observed Jupiter in February 2003 for four rotations of the planet (approximately 40 hours) during intense auroral activity. These Chandra observations, taken with its Advanced CCD Imaging Spectrometer, were accompanied by one-and-a-half hours of Hubble Space Telescope observations at ultraviolet wavelengths. The research team also included Noe Lugaz, Hunter Waite, and Tariq Majeed (University of Michigan, Ann Arbor), Thomas Cravens (University of Kansas, Lawrence), Randy Gladstone (Southwest Research Institute, San Antonio, Texas), Peter Ford (Massachusetts Institute of Technology, Cambridge), Denis Grodent (University of Liege, Belgium), Anil Bhardwaj (Marshall Space Flight Center) and Robert MacDowell and Michael Desch (Goddard Space Flight Center, Greenbelt, Md.) NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA's Office of Space Science, Washington. Northrop Grumman of Redondo Beach, Calif., formerly TRW, Inc., was the prime

The survival of large organic molecules during hypervelocity impacts with water ice: implications for sampling the icy surfaces of moons

NASA Astrophysics Data System (ADS)

Hurst, A.; Bowden, S. A.; Parnell, J.; Burchell, M. J.; Ball, A. J.

2007-12-01

There are a number of measurements relevant to planetary geology that can only be adequately performed by physically contacting a sample. This necessitates landing on the surface of a moon or planetary body or returning samples to earth. The need to physically contact a sample is particularly important in the case of measurements that could detect medium to low concentrations of large organic molecules present in surface materials. Large organic molecules, although a trace component of many meteoritic materials and rocks on the surface of earth, carry crucial information concerning the processing of meteoritic material in the surface and subsurface environments, and can be crucial indicators for the presence of life. Unfortunately landing on the surface of a small planetary body or moon is complicated, particularly if surface topography is only poorly characterised and the atmosphere thin thus requiring a propulsion system for a soft landing. One alternative to a surface landing may be to use an impactor launched from an orbiting spacecraft to launch material from the planets surface and shallow sub-surface into orbit. Ejected material could then be collected by a follow-up spacecraft and analyzed. The mission scenario considered in the Europa-Ice Clipper mission proposal included both sample return and the analysis of captured particles. Employing such a sampling procedure to analyse large organic molecules is only viable if large organic molecules present in ices survive hypervelocity impacts (HVIs). To investigate the survival of large organic molecules in HVIs with icy bodies a two stage light air gas gun was used to fire steel projectiles (1-1.5 mm diameter) at samples of water ice containing large organic molecules (amino acids, anthracene and beta-carotene a biological pigment) at velocities > 4.8 km/s.UV-VIS spectroscopy of ejected material detected beta-carotene indicating large organic molecules can survive hypervelocity impacts. These preliminary results

Plasma IMS Composition Measurements for Europa and the Other Galilean Moons

NASA Astrophysics Data System (ADS)

Sittler, Edward; Cooper, John; Hartle, Richard; Lipatov, Alexander; Mahaffy, Paul; Paterson, William; Pachalidis, Nick; Coplan, Mike; Cassidy, Tim

2010-05-01

NASA and ESA are planning the joint Europa Jupiter System Mission (EJSM) to the Jupiter system with specific emphasis to Europa and Ganymede, respectively. The Japanese Space Agency is also planning an orbiter mission to explore Jupiter's magnetosphere and the Galilean satellites. For NASA's Jupiter Europa Orbiter (JEO) we are developing the 3D Ion Mass Spectrometer (IMS) with two main goals which can also be applied to the other Galilean moons, 1) measure the plasma interaction between Europa and Jupiter's magnetosphere and 2) infer the 4? surface composition to trace elemental [1] and significant isotopic levels. The first goal supports the magnetometer (MAG) measurements, primarily directed at detection of Europa's sub-surface ocean, while the second gives information about transfer of material between the Galilean moons, and between the moon surfaces and subsurface layers putatively including oceans. The measurement of the interactions for all the Galilean moons can be used to trace the in situ ion measurements of pickup ions back to either Europa's or Ganymede's surface from the respectively orbiting spacecraft. The IMS instrument, being developed under NASA's Astrobiology Instrument Development Program, would maximally achieve plasma measurement requirements for JEO and EJSM while moving forward our knowledge of Jupiter system composition and source processes to far higher levels than previously envisaged. The composition of the global surfaces of Europa and Ganymede can be inferred from the measurement of ejected neutrals and pick-up ions using at minimum an in situ payload including MAG and IMS also fully capable of meeting Level 1 mission requirements for ocean detection and survey. Elemental and isotopic analysis of potentially extruded oceanic materials at the moon surfaces would further support the ocean objectives. These measurements should be made from a polar orbiting spacecraft about Europa or Ganymede at height ~ 100 km. The ejecta produced by

The Jovian rings as observed from Jupiter.

NASA Astrophysics Data System (ADS)

Malinnikova Bang, A.; Joergensen, J. L.; Joergensen, P. S.; Denver, T.; Connerney, J. E. P.; Bolton, S. J.; Levin, S.

2017-12-01

Juno entered a highly eliptic orbit around Jupiter on the 4. July 2016. Since then, it has completed 8 perijove passages. The Magnetometer experiment consists of two measurement platforms mounted 10m and 12m from the spacecraft spin axis, on one of three large solar panels. Each magnetometer platform is equipped with two star trackers to provide accurate attitude information to the vector magnetometers. The star trackers are pointed 13deg from the (anti) spin vector, and clocked 180deg to avoid simultaneous blinding effects from bright Jupiter only 6000km away, during perijove. This brings Juno well inside the innermost known satellite, Metis. The star trackers pointing close to, and above the Jovian horizon for most of each rotation of Juno, has an excellent view of the Jovian ring systems with a beta-angle close to 180deg. We report on the ring imaging performed during the first 8 orbits, discuss the structure, optical depth and moon sheparding of the inner rings as measured so far.

TRANSIT MODEL OF PLANETS WITH MOON AND RING SYSTEMS

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

Tusnski, Luis Ricardo M.; Valio, Adriana, E-mail: lrtusnski@das.inpe.br, E-mail: avalio@craam.mackenzie.br

2011-12-10

Since the discovery of the first exoplanets, those most adequate for life to begin and evolve have been sought. Due to observational bias, however, most of the discovered planets so far are gas giants, precluding their habitability. However, if these hot Jupiters are located in the habitable zones of their host stars, and if rocky moons orbit them, then these moons may be habitable. In this work, we present a model for planetary transit simulation considering the presence of moons and planetary rings around a planet. The moon's orbit is considered to be circular and coplanar with the planetary orbit.more » The other physical and orbital parameters of the star, planet, moon, and rings can be adjusted in each simulation. It is possible to simulate as many successive transits as desired. Since the presence of spots on the surface of the star may produce a signal similar to that of the presence of a moon, our model also allows for the inclusion of starspots. The result of the simulation is a light curve with a planetary transit. White noise may also be added to the light curves to produce curves similar to those obtained by the CoRoT and Kepler space telescopes. The goal is to determine the criteria for detectability of moons and/or ring systems using photometry. The results show that it is possible to detect moons with radii as little as 1.3 R{sub Circled-Plus} with CoRoT and 0.3 R{sub Circled-Plus} with Kepler.« less

Life detection strategy for Jovian's icy moons: Lessons from subglacial Lake Vostok exploration

NASA Astrophysics Data System (ADS)

Bulat, Sergey; Alekhina, Irina; Marie, Dominique; Petit, Jean-Robert

2010-05-01

The objective was to estimate the microbial content of accretion ice originating from the subglacial Lake Vostok buried beneath 4-km thick East Antarctic ice sheet with the ultimate goal to discover microbial life in this extreme icy environment. The DNA study constrained by Ancient DNA research criteria was used as a main approach. The flow cytometry was implemented in cell enumerating. As a result, both approaches showed that the accretion ice contains the very low unevenly distributed biomass indicating that the water body should also be hosting a highly sparse life. Up to now, the only accretion ice featured by mica-clay sediments presence allowed the recovery a pair of bacterial phylotypes. This unexpectedly included the chemolithoautotrophic thermophile Hydrogenophilus thermoluteolus and one more unclassified phylotype both passing numerous contaminant controls. In contrast, the deeper and cleaner accretion ice with no sediments presence and near detection limit gas content gave no reliable signals. Thus, the results obtained testify that the search for life in the Lake Vostok is constrained by a high chance of forward-contamination. The subglacial Lake Vostok seems to represent the only extremely clean giant aquatic system on the Earth providing a unique test area for searching for life on icy worlds. The life detection strategy for (sub)glacial environments elsewhere (e.g., Jovian's Europa) should be based on stringent decontamination procedures in clean-room facilities, establishment of on-site contaminant library, implementation of appropriate methods to reach detection level for signal as low as possible, verification of findings through ecological settings of a given environment and repetition at an independent laboratory within the specialized laboratory network.

The Icy Mountains of Pluto

NASA Image and Video Library

2015-07-15

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

Particle Environment Package (PEP) for the ESA JUICE mission

NASA Astrophysics Data System (ADS)

Barabash, Stas; Brandt, Pontus; Wurz, Peter; PEP Team

2016-10-01

PEP is a suite of six (6) sensors arranged in 4 units to measure charged and neutral particles in the Jupiter magnetospheres and at the moons to answer four overarching science questions:1. How does the corotating magnetosphere of Jupiter interact with the complex and diverse environment of Ganymede?2. How does the rapidly rotating magnetosphere of Jupiter interact with the seemingly inert Callisto?3. What are the governing mechanisms and their global impacts of release of material into the Jovian magnetosphere from seemingly inert Europa and active Io?4. How do internal and solar wind drivers cause such energetic, time variable and multi-scale phenomena in the steadily rotating giant magnetosphere of Jupiter?PEP measures positive and negative ions, electrons, exospheric neutral gas, thermal plasma and energetic neutral atoms present in all domains of the Jupiter system over nine decades of energy from < 0.001 eV to > 1 MeV with full angular coverage.PEP provides instantaneous measurements of 3D flow of the ion plasma and composition to understand the magnetosphere and magnetosphere-moon interactions. It also measures instantaneously 3D electron plasma to investigate auroral processes at the moon and Jupiter. Measurements of the angular distributions of energetic electrons at sub-second resolution probe the acceleration mechanisms and magnetic field topology and boundaries.PEP combines global imaging via remote sensing using energetic neutral atoms (ENA) with in-situ measurements and performs global imaging of Europa/Io tori and magnetosphere combined with energetic ion measurements. Using low energy ENAs originating from the particle - surface interaction PEP investigate space weathering of the icy moons by precipitation particles. PEP will first-ever directly sample of the exospheres of Europa, Ganymede, and Callisto with extremely high mass resolution (M/ΔM > 1100).The PEP sensors are (1) an ion mass analyzer, (2) an electron spectrometer, (3) a low energy ENA

Optical design and stray light analysis for the JANUS camera of the JUICE space mission

NASA Astrophysics Data System (ADS)

Greggio, D.; Magrin, D.; Munari, M.; Zusi, M.; Ragazzoni, R.; Cremonese, G.; Debei, S.; Friso, E.; Della Corte, V.; Palumbo, P.; Hoffmann, H.; Jaumann, R.; Michaelis, H.; Schmitz, N.; Schipani, P.; Lara, L. M.

2015-09-01

The JUICE (JUpiter ICy moons Explorer) satellite of the European Space Agency (ESA) is dedicated to the detailed study of Jupiter and its moons. Among the whole instrument suite, JANUS (Jovis, Amorum ac Natorum Undique Scrutator) is the camera system of JUICE designed for imaging at visible wavelengths. It will conduct an in-depth study of Ganymede, Callisto and Europa, and explore most of the Jovian system and Jupiter itself, performing, in the case of Ganymede, a global mapping of the satellite with a resolution of 400 m/px. The optical design chosen to meet the scientific goals of JANUS is a three mirror anastigmatic system in an off-axis configuration. To ensure that the achieved contrast is high enough to observe the features on the surface of the satellites, we also performed a preliminary stray light analysis of the telescope. We provide here a short description of the optical design and we present the procedure adopted to evaluate the stray-light expected during the mapping phase of the surface of Ganymede. We also use the results obtained from the first run of simulations to optimize the baffle design.

Experimental Thermodynamics of [Na-Mg-Cl-SO4] Aqueous Solutions at GPa Pressure With Application to Icy Worlds.

NASA Astrophysics Data System (ADS)

Brown, J. M.; Bollengier, O.; Vance, S.

2017-12-01

Water competes with silicates as the main constituent of solid bodies in the outer solar system. Ganymede and Titan, the Mercury-sized satellites of Jupiter and Saturn, are made up half of water present as massive hydrospheres where pressure can reach up to 1.5 GPa. Geophysical data and planetary models unequivocally support the existence of global aqueous oceans trapped in these hydrospheres. However, the extent of these oceans and their role in the processes governing the internal structure of these moons remain unresolved. At issue is the poor to non-existent characterization, at the relevant pressures, of the properties of the aqueous fluids of significance to the outer solar system (with notably the Na-Mg-Cl-SO4 salts found in primitive chondrites), forcing current models to rely on pure water only. Our team at the University of Washington has developed an experimental apparatus to acquire the speed of sound of aqueous solutions in the 0 - 0.7 GPa and 250 - 350 K pressure and temperature ranges covering most of the conditions of existence of these extra-terrestrial oceans. Speeds of sound measured over a grid of pressures and temperatures allow calculation of the thermodynamic quantities (G, ρ, μ...) required for planetary science. Early analysis of pure water samples indicates our experimental results are on par with (at lower pressures), or better than, the IAPWS water laboratory standard, with sound speeds determined to 0.02% over our entire pressure range. For the first time at the high pressures of interest for large icy moons, we achieved the exploration of H2O-NaCl, H2O-MgSO4, H2O-Na2SO4 and H2O-MgCl2 solutions, from dilute concentrations to saturation. We are now in the process of acquiring the first data for H2O-NaCl-MgSO4 mixtures. We will briefly present our experimental setup and the underlying sound speed theory, and will then compare our results for the four endmembers, with an emphasis on their different association behavior under pressure as

Re-Analysis of the Solar Phase Curves of the Icy Galilean Satellites

NASA Technical Reports Server (NTRS)

Domingue, Deborah; Verbiscer, Anne

1997-01-01

Re-analysis of the solar phase curves of the icy Galilean satellites demonstrates that the quantitative results are dependent on the single particle scattering function incorporated into the photometric model; however, the qualitative properties are independent. The results presented here show that the general physical characteristics predicted by a Hapke model (B. Hapke, 1986, Icarus 67, 264-280) incorporating a two parameter double Henyey-Greenstein scattering function are similar to the predictions given by the same model incorporating a three parameter double Henyey-Greenstein scattering function as long as the data set being modeled has adequate coverage in phase angle. Conflicting results occur when the large phase angle coverage is inadequate. Analysis of the role of isotropic versus anisotropic multiple scattering shows that for surfaces as bright as Europa the two models predict very similar results over phase angles covered by the data. Differences arise only at those phase angles for which there are no data. The single particle scattering behavior between the leading and trailing hemispheres of Europa and Ganymede is commensurate with magnetospheric alterations of their surfaces. Ion bombardment will produce more forward scattering single scattering functions due to annealing of potential scattering centers within regolith particles (N. J. Sack et al., 1992, Icarus 100, 534-540). Both leading and trailing hemispheres of Europa are consistent with a high porosity model and commensurate with a frost surface. There are no strong differences in predicted porosity between the two hemispheres of Callisto, both are consistent with model porosities midway between that deduced for Europa and the Moon. Surface roughness model estimates predict that surface roughness increases with satellite distance from Jupiter, with lunar surface roughness values falling midway between those measured for Ganymede and Callisto. There is no obvious variation in predicted surface

Hubble Spies Spooky Shadow on Jupiter's Giant Eye (color)

NASA Image and Video Library

2014-10-28

This trick that the planet is looking back at you is actually a Hubble treat: An eerie, close-up view of Jupiter, the biggest planet in our solar system. Hubble was monitoring changes in Jupiter’s immense Great Red Spot (GRS) storm on April 21, 2014, when the shadow of the Jovian moon, Ganymede, swept across the center of the storm. This gave the giant planet the uncanny appearance of having a pupil in the center of a 10,000 mile-diameter “eye.” For a moment, Jupiter “stared” back at Hubble like a one-eyed giant Cyclops. Credit: NASA, ESA, and A. Simon (Goddard Space Flight Center) 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

Numerical simulation of Ganymede's ionosphere

NASA Astrophysics Data System (ADS)

Carnielli, Gianluca; Galand, Marina; Leblanc, François; Leclercq, Ludivine; Modolo, Ronan

2017-04-01

Ganymede is one of the four Galilean moons that orbit around Jupiter and the key moon targeted by the JUpiter and ICy moons Explorer (JUICE) mission. Other than being the largest moon in the solar system, it is also the only one known to generate internally a magnetic field which is strong enough to overcome the background jovian field; thus, the moon carves out its own magnetosphere inside that of Jupiter. In addition, at Ganymede's orbit the jovian plasma is sub-Alfvénic and subsonic. The interaction of Ganymede's magnetosphere with its surroundings therefore differs from that of planetary magnetospheres resulting from the interaction with the super-Alfvénic and supersonic solar wind. All this makes Ganymede a peculiar celestial body to study. One of the main goals of the JUICE mission is to characterize Ganymede's exosphere, ionosphere, and magnetosphere as well as its interaction with the jovian surrounding in great details. Ahead of the arrival of JUICE at Jupiter, models have been developed to predict Ganymede's environment. Observational constraints are primarily given from Galileo and from Earth-based telescopes. They remain limited, especially in terms of the ionospheric number density and temperature. To address the currently poorly constrained ionospheric environment, we have developed a test particle model of Ganymede's plasma environment. The model is driven by the densities of neutral species from the exospheric model of Leblanc et al. (Icarus, 2016) and the electromagnetic field taken from the hybrid model of Leclercq et al. (PSS, 2016). The simulation follows the motion of millions of test particles in the environment of the moon and allows to generate maps of ion densities, bulk velocities, and temperatures. We will present simulation outcomes for different ions, including H+, O+, and O2+. We will also discuss how the results from the simulations are relevant to MHD and exospheric models and in interpreting plasma and particle data obtained by

Laboratory Reference Spectroscopy of Icy Satellite Candidate Surface Materials (Invited)

NASA Astrophysics Data System (ADS)

Dalton, J. B.; Jamieson, C. S.; Shirley, J. H.; Pitman, K. M.; Kariya, M.; Crandall, P.

2013-12-01

Pitman, 2012). We will report on recent results, including spectra of sulfate hydrates, simple organic molecules, and volatile ices measured at PICL in support of past, present and planned missions. We gratefully acknowledge the support of JPL's Research and Technology Development and Strategic Hire Programs, and of the NASA Outer Planets Research and Planetary Geology and Geophysics programs. Dalton, III, J.B., Spectroscopy of icy moon surface materials, Space Sci. Rev. 153:219-247, 2010. Dalton, III, J.B., and Pitman, K.M., Low temperature optical constants of some hydrated sulfates relevant to planetary surfaces, J. Geophys. Res. 117:E09001, doi:10.1029/2011JE004036, 2012. Hapke, B.W., Bidirectional reflectance spectroscopy I. Theory, J. Geophys. Res. 86, 3039-3054, 1981. Shkuratov, Y., L. Starukhina, H. Hoffmann, and G. Arnold, A model of spectral albedo of particulate surfaces: Implications for optical properties of the Moon, Icarus 137, 235-246, 1999.

Nano Icy Moons Propellant Harvester

NASA Technical Reports Server (NTRS)

VanWoerkom, Michael (Principal Investigator)

2017-01-01

As one of just a few bodies identified in the solar system with a liquid ocean, Europa has become a top priority in the search for life outside of Earth. However, cost estimates for exploring Europa have been prohibitively expensive, with estimates of a NASA Flagship class orbiter and lander approaching $5 billion. ExoTerra's NIMPH offers an affordable solution that can not only land, but return a sample from the surface to Earth. NIMPH combines solar electric propulsion (SEP) technologies being developed for the asteroid redirect mission and microsatellite electronics to reduce the cost of a full sample return mission below $500 million. A key to achieving this order-of-magnitude cost reduction is minimizing the initial mass of the system. The cost of any mission is directly proportional to its mass. By keeping the mission within the constraints of an Atlas V 551 launch vehicle versus an SLS, we can significantly reduce launch costs. To achieve this we reduce the landed mass of the sample return lander, which is the largest multiplier of mission mass, and shrink propellant mass through high efficiency SEP and gravity assists. The NIMPH projects first step in reducing landed mass focuses on development of a micro-In Situ Resource Utilization (micro-ISRU) system. ISRU allows us to minimize landed mass of a sample return mission by converting local ice into propellants. The project reduces the ISRU system to a CubeSat-scale package that weighs just 1.74 kg and consumes just 242 W of power. We estimate that use of this ISRU vs. an identical micro-lander without ISRU reduces fuel mass by 45 kg. As the dry mass of the lander grows for larger missions, these savings scale exponentially. Taking full advantage of the micro-ISRU system requires the development of a micro-liquid oxygen-liquid hydrogen engine. The micro-liquid oxygen-liquid hydrogen engine is tailored for the mission by scaling it to match the scale of the micro-lander and the low gravity of the target moon

Gravity is the Key Experiment to Address the Habitability of the Ocean in Jupiter's Moon Europa

NASA Astrophysics Data System (ADS)

Sessa, A. M.; Dombard, A. J.

2013-12-01

Life requires three constituents: a liquid solvent (i.e., water), a chemical system that can form large molecules to record genetic information (e.g., carbon based) as well as chemical nutrients (e.g., nitrogen, phosphorous), and a chemical disequilibrium system that can provide metabolic energy. While it is believed that there is a saline water layer located between the rock and ice layers in Jupiter's moon Europa, which would satisfy the first requirement, it is unknown if the other conditions are currently met. The likelihood that Europa is a haven for life in our Solar System skyrockets, however, if there is currently active volcanism at the rock-water interface, much the same that volcanic processes enable the chemosynthetic life that forms the basis of deep sea-vent communities at the bottom of Earth's oceans. Exploring the volcanic activity on this interface is challenging, as direct observation via a submersible or high-resolution indirect observations via a dense global seismic network on the surface is at present technically (and fiscally!) untenable. Thus, gravity studies are the best way to explore currently the structure of this all-important interface. Though mostly a silicate body with only a relatively thin (~100 km) layer of water, Europa is different from the terrestrial planets in that this rock-water interface, and not the surface, represents the largest density contrast across the moon's near-surface layers, and thus topography on this interface could conceivably dominate the gravity. Here, we calculate the potential anomalies that arise from topography on the surface, the water-ice interface (at 20 km depth), and the rock-water interface, finding that the latter dominates the free-air gravity at the longest wavelengths (spherical harmonic degrees < 10) and the Bouguer gravity at intermediate wavelengths (degrees ~10-50), and only for the shortest wavelengths (degrees > 50) does the water-ice interface (and presumably mass-density anomalies

Studies of Plasma Flow Past Jupiters Satellite Io

NASA Technical Reports Server (NTRS)

Linker, Jon A.

1997-01-01

We have investigated the interaction of Io, Jupiter's innermost Galilean satellite, with the Io plasma torus, and the interaction of Ganymede with the corotating Jovian plasma. With the successful insertion of the Galileo spacecraft into orbit around Jupiter, many new observations have been made of the Jovian magnetosphere. Some of the most exciting results thus far have been in regards to Jupiter's satellites, Io and Ganymede. In both cases the large perturbations to the background (Jovian) magnetic field have been consistent with the satellites' possession of an intrinsic magnetic field. The gravity measurements implying a differentiated core at both Io and Ganymede makes internal generation of a magnetic field by dynamo action in these satellites plausible, and, in the case of Ganymede, the identification of an intrinsic field is apparently unambiguous. For Io the situation is less clear, and further analysis is necessary to answer this important question. During the past year, we have used time-dependent three-dimensional magnetohydrodynamic (MHD) simulations to study these plasma-moon interactions. The results from these simulations have been used directly in the analysis of the Galileo magnetometer data. Our primary emphasis has been on the Io interaction, but we recently presented results on the Ganymede interaction as well. In this progress summary we describe our efforts on these problems to date.

Titan's Impact Cratering Record: Erosion of Ganymedean (and other) Craters on a Wet Icy Landscape

NASA Astrophysics Data System (ADS)

Schenk, P.; Moore, J.; Howard, A.

2012-04-01

We examine the cratering record of Titan from the perspective of icy satellites undergoing persistent landscape erosion. First we evaluate whether Ganymede (and Callisto) or the smaller low-gravity neighboring icy satellites of Saturn are the proper reference standard for evaluating Titan’s impact crater morphologies, using topographic and morphometric measurements (Schenk, 2002; Schenk et al. (2004) and unpublished data). The special case of Titan’s largest crater, Minrva, is addressed through analysis of large impact basins such as Gilgamesh, Lofn, Odysseus and Turgis. Second, we employ a sophisticated landscape evolution and modification model developed for study of martian and other planetary landforms (e.g., Howard, 2007). This technique applies mass redistribution principles due to erosion by impact, fluvial and hydrological processes to a planetary landscape. The primary advantage of our technique is the possession of a limited but crucial body of areal digital elevation models (DEMs) of Ganymede (and Callisto) impact craters as well as global DEM mapping of Saturn’s midsize icy satellites, in combination with the ability to simulate rainfall and redeposition of granular material to determine whether Ganymede craters can be eroded to resemble Titan craters and the degree of erosion required. References: Howard, A. D., “Simulating the development of martian highland landscapes through the interaction of impact cratering, fluvial erosion, and variable hydrologic forcing”, Geomorphology, 91, 332-363, 2007. Schenk, P. "Thickness constraints on the icy shells of the galilean satellites from impact crater shapes". Nature, 417, 419-421, 2002. Schenk, P.M., et al. "Ages and interiors: the cratering record of the Galilean satellites". In: Jupiter: The Planet, Satellites, and Magnetosphere, Cambridge University Press, Cambridge, UK, pp. 427-456, 2004.

Europa Rising

NASA Technical Reports Server (NTRS)

2007-01-01

New Horizons took this image of the icy moon Europa rising above Jupiter's cloud tops with its Long Range Reconnaissance Imager (LORRI) at 11:48 Universal Time on February 28, 2007, six hours after the spacecraft's closest approach to Jupiter.

The picture was one of a handful of the Jupiter system that New Horizons took primarily for artistic, rather than scientific, value. This particular scene was suggested by space enthusiast Richard Hendricks of Austin, Texas, in response to an Internet request by New Horizons scientists for evocative, artistic imaging opportunities at Jupiter.

The spacecraft was 2.3 million kilometers (1.4 million miles) from Jupiter and 3 million kilometers (1.8 million miles) from Europa when the picture was taken. Europa's diameter is 3,120 kilometers (1,939 miles). The image is centered on Europa coordinates 5 degrees south, 6 degrees west. In keeping with its artistic intent - and to provide a more dramatic perspective - the image has been rotated so south is at the top.

Potential Jupiter-Family comet contamination of the main asteroid belt

NASA Astrophysics Data System (ADS)

Hsieh, Henry H.; Haghighipour, Nader

2016-10-01

We present the results of "snapshot" numerical integrations of test particles representing comet-like and asteroid-like objects in the inner Solar System aimed at investigating the short-term dynamical evolution of objects close to the dynamical boundary between asteroids and comets as defined by the Tisserand parameter with respect to Jupiter, TJ (i.e., TJ = 3). As expected, we find that TJ for individual test particles is not always a reliable indicator of initial orbit types. Furthermore, we find that a few percent of test particles with comet-like starting elements (i.e., similar to those of Jupiter-family comets) reach main-belt-like orbits (at least temporarily) during our 2 Myr integrations, even without the inclusion of non-gravitational forces, apparently via a combination of gravitational interactions with the terrestrial planets and temporary trapping by mean-motion resonances with Jupiter. We estimate that the fraction of real Jupiter-family comets occasionally reaching main-belt-like orbits on Myr timescales could be on the order of ∼ 0.1-1%, although the fraction that remain on such orbits for appreciable lengths of time is certainly far lower. For this reason, the number of JFC-like interlopers in the main-belt population at any given time is likely to be small, but still non-zero, a finding with significant implications for efforts to use apparently icy yet dynamically asteroidal main-belt comets as tracers of the primordial distribution of volatile material in the inner Solar System. The test particles with comet-like starting orbital elements that transition onto main-belt-like orbits in our integrations appear to be largely prevented from reaching low eccentricity, low inclination orbits, suggesting that the real-world population of main-belt objects with both low eccentricities and inclinations may be largely free of this potential occasional Jupiter-family comet contamination. We therefore find that low-eccentricity, low-inclination main

Jupiter's Main Ring/Ring Halo

NASA Technical Reports Server (NTRS)

1997-01-01

faintest are purple.

Jupiter's main ring is a thin strand of material encircling the planet. The diffuse innermost boundary begins at approximately 123,000 kilometers (76,429 miles). The main ring's outer radius is found to be at 128,940 kilometers (80,119 miles) +/-50 kilometers (31 miles), slightly less than the Voyager value of 129,130 kilometers (80,237 miles) +/-100 kilometers (62 miles), but very close to the orbit of the satellite Adrastea (128,980 kilometers or 80,144 miles). The main ring exhibits a marked drop in brightness at 127,849 kilometers (79,441 miles) +/-50 kilometers (31 miles), lying almost atop the orbit of the Jovian moon Metis at 127,978 kilometers (79,521 miles). Satellites seem to affect the structure of even tenuous rings like those found at Jupiter.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

The Primordial Destruction of Moons around Giant Exoplanets through Disk-Driven Planetary Migration

NASA Astrophysics Data System (ADS)

Spalding, Christopher; Batygin, Konstantin; Adams, Fred C.

2015-11-01

The extensive array of satellites around Jupiter and Saturn makes it reasonable to suspect that similar systems of moons might exist around giant extrasolar planets. Observational surveys have revealed a significant population of such giant planets residing at distances of about 1 AU, leading to speculation that some of these 'exomoons' might be capable of maintaining liquid water on their surfaces. Accordingly, many recent efforts have specifically hunted for moons around giant exoplanets. Owing to the lack of detections thus far, it is worth asking whether certain processes intrinsic to planet formation might lead to the loss of moons. Here, we highlight that giant planets are thought to undergo inward migration within their natal disks and show that the very process of migration naturally captures moons into a so-called "evection resonance". Within this resonance, the lunar orbit's eccentricity grows until the moon is lost, either by collision with the planet or through tidal disruption. Whether moons survive or not is critically dependent upon where the planet began its inward trek. In this way, the presence or absence of exomoons can inform us on the extent of inward migration, for which no reliable observational proxy currently exists.

Asteroid Ida and Its Moon

NASA Technical Reports Server (NTRS)

1994-01-01

This is the first full picture showing both asteroid 243 Ida and its newly discovered moon to be transmitted to Earth from the National Aeronautics and Space Administration's (NASA's) Galileo spacecraft--the first conclusive evidence that natural satellites of asteroids exist. Ida, the large object, is about 56 kilometers (35 miles) long. Ida's natural satellite is the small object to the right. This portrait was taken by Galileo's charge-coupled device (CCD) camera on August 28, 1993, about 14 minutes before the Jupiter-bound spacecraft's closest approach to the asteroid, from a range of 10,870 kilometers (6,755 miles). Ida is a heavily cratered, irregularly shaped asteroid in the main asteroid belt between Mars and Jupiter--the 243rd asteroid to be discovered since the first was found at the beginning of the 19th century. Ida is a member of a group of asteroids called the Koronis family. The small satellite, which is about 1.5 kilometers (1 mile) across in this view, has yet to be given a name by astronomers. It has been provisionally designated '1993 (243) 1' by the International Astronomical Union. ('1993' denotes the year the picture was taken, '243' the asteroid number and '1' the fact that it is the first moon of Ida to be found.) Although appearing to be 'next' to Ida, the satellite is actually in the foreground, slightly closer to the spacecraft than Ida is. Combining this image with data from Galileo's near-infrared mapping spectrometer, the science team estimates that the satellite is about 100 kilometers (60 miles) away from the center of Ida. This image, which was taken through a green filter, is one of a six-frame series using different color filters. The spatial resolution in this image is about 100 meters (330 feet) per pixel.

Asteroid Ida and Its Moon

NASA Image and Video Library

1996-02-01

This is the first full picture showing both asteroid 243 Ida and its newly discovered moon to be transmitted to Earth from the National Aeronautics and Space Administration's (NASA's) Galileo spacecraft--the first conclusive evidence that natural satellites of asteroids exist. Ida, the large object, is about 56 kilometers (35 miles) long. Ida's natural satellite is the small object to the right. This portrait was taken by Galileo's charge-coupled device (CCD) camera on August 28, 1993, about 14 minutes before the Jupiter-bound spacecraft's closest approach to the asteroid, from a range of 10,870 kilometers (6,755 miles). Ida is a heavily cratered, irregularly shaped asteroid in the main asteroid belt between Mars and Jupiter -- the 243rd asteroid to be discovered since the first was found at the beginning of the 19th century. Ida is a member of a group of asteroids called the Koronis family. The small satellite, which is about 1.5 kilometers (1 mile) across in this view, has yet to be given a name by astronomers. It has been provisionally designated '1993 (243) 1' by the International Astronomical Union. ('1993' denotes the year the picture was taken, '243' the asteroid number and '1' the fact that it is the first moon of Ida to be found.) Although appearing to be 'next' to Ida, the satellite is actually in the foreground, slightly closer to the spacecraft than Ida is. Combining this image with data from Galileo's near-infrared mapping spectrometer, the science team estimates that the satellite is about 100 kilometers (60 miles) away from the center of Ida. This image, which was taken through a green filter, is one of a six-frame series using different color filters. The spatial resolution in this image is about 100 meters (330 feet) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA00136

Space Weathering Perspectives on Europa Amidst the Tempest of the Jupiter Magnetospheric System

NASA Technical Reports Server (NTRS)

Cooper, J. F.; Hartle, R. E.; Lipatov, A. S.; Sittler, E. C.; Cassidy, T. A.; Ip. W.-H.

2010-01-01

Europa resides within a "perfect storm" tempest of extreme external field, plasma, and energetic particle interactions with the magnetospheric system of Jupiter. Missions to Europa must survive, functionally operate, make useful measurements, and return critical science data, while also providing full context on this ocean moon's response to the extreme environment. Related general perspectives on space weathering in the solar system are applied to mission and instrument science requirements for Europa.

Gravity field of Jupiter’s moon Amalthea and the implication on a spacecraft trajectory

NASA Astrophysics Data System (ADS)

Weinwurm, Gudrun

2006-01-01

Before its final plunge into Jupiter in September 2003, GALILEO made a last 'visit' to one of Jupiter's moons - Amalthea. This final flyby of the spacecraft's successful mission occurred on November 5, 2002. In order to analyse the spacecraft data with respect to Amalthea's gravity field, interior models of the moon had to be provided. The method used for this approach is based on the numerical integration of infinitesimal volume elements of a three-axial ellipsoid in elliptic coordinates. To derive the gravity field coefficients of the body, the second method of Neumann was applied. Based on the spacecraft trajectory data provided by the Jet Propulsion Laboratory, GALILEO's velocity perturbations at closest approach could be calculated. The harmonic coefficients of Amalthea's gravity field have been derived up to degree and order six, for both homogeneous and reasonable heterogeneous cases. Founded on these numbers the impact on the trajectory of GALILEO was calculated and compared to existing Doppler data. Furthermore, predictions for future spacecraft flybys were derived. No two-way Doppler-data was available during the flyby and the harmonic coefficients of the gravity field are buried in the one-way Doppler-noise. Nevertheless, the generated gravity field models reflect the most likely interior structure of the moon and can be a basis for further exploration of the Jovian system.

Space Weathering on Icy Satellites in the Outer Solar System

NASA Technical Reports Server (NTRS)

Clark, R. N.; Perlman, Z.; Pearson, N.; Cruikshank, D. P.

2014-01-01

Space weathering produces well-known optical effects in silicate minerals in the inner Solar System, for example, on the Moon. Space weathering from solar wind and UV (ultraviolet radiation) is expected to be significantly weaker in the outer Solar System simply because intensities are low. However, cosmic rays and micrometeoroid bombardment would be similar to first order. That, combined with the much higher volatility of icy surfaces means there is the potential for space weathering on icy outer Solar System surfaces to show optical effects. The Cassini spacecraft orbiting Saturn is providing evidence for space weathering on icy bodies. The Cassini Visible and Infrared Mapping Spectrometer (VIMS) instrument has spatially mapped satellite surfaces and the rings from 0.35-5 microns and the Ultraviolet Imaging Spectrograph (UVIS) instrument from 0.1 to 0.2 microns. These data have sampled a complex mixing space between H2O ice and non-ice components and they show some common spectral properties. Similarly, spectra of the icy Galilean satellites and satellites in the Uranian system have some commonality in spectral properties with those in the Saturn system. The UV absorber is spectrally similar on many surfaces. VIMS has identified CO2, H2 and trace organics in varying abundances on Saturn's satellites. We postulate that through the spatial relationships of some of these compounds that they are created and destroyed through space weathering effects. For example, the trapped H2 and CO2 observed by VIMS in regions with high concentrations of dark material may in part be space weathering products from the destruction of H2O and organic molecules. The dark material, particularly on Iapetus which has the highest concentration in the Saturn system, is well matched by space-weathered silicates in the .4 to 2.6 micron range, and the spectral shapes closely match those of the most mature lunar soils, another indicator of space weathered material.

Precision Navigation of Cassini Images Using Rings, Icy Satellites, and Fuzzy Bodies

NASA Astrophysics Data System (ADS)

French, Robert S.; Showalter, Mark R.; Gordon, Mitchell K.

2016-10-01

Before images from the Cassini spacecraft can be analyzed, errors in the published pointing information (up to ~110 pixels for the Imaging Science Subsystem Narrow Angle Camera) must be corrected so that the line of sight vector for each pixel is known. This complicated and labor-intensive process involves matching the image contents with known features such as stars, rings, or moons. Metadata, such as lighting geometry or ring radius and longitude, must be computed for each pixel as well. Both steps require mastering the SPICE toolkit, a highly capable piece of software with a steep learning curve. Only after these steps are completed can the actual scientific investigation begin.We have embarked on a three-year project to perform these steps for all 400,000+ Cassini ISS images as well as images taken by the VIMS, UVIS, and CIRS instruments. The result will be a series of SPICE kernels that include accurate pointing information and a series of backplanes that include precomputed metadata for each pixel. All data will be made public through the PDS Ring-Moon Systems Node (http://www.pds-rings.seti.org). We expect this project to dramatically decrease the time required for scientists to analyze Cassini data.In a previous poster (French et al. 2014, DPS #46, 422.01) we discussed our progress navigating images using stars, simple ring models, and well-defined icy bodies. In this poster we will report on our current progress including the use of more sophisticated ring models, navigation of "fuzzy" bodies such as Titan and Saturn, and use of crater matching on high-resolution images of the icy satellites.

NASA Spacecraft Sees 'Pac-Man' on Saturn Moon

NASA Image and Video Library

2017-12-08

NASA release date March 29, 2010 The highest-resolution-yet temperature map and images of Saturn’s icy moon Mimas obtained by NASA’s Cassini spacecraft reveal surprising patterns on the surface of the small moon, including unexpected hot regions that resemble “Pac-Man” eating a dot, and striking bands of light and dark in crater walls. The left portion of this image shows Mimas in visible light, an image that has drawn comparisons to the "Star Wars" Death Star. The right portion shows the new temperature map, which resembles 1980s video game icon "Pac Man." To learn more about this image go to: www.nasa.gov/centers/goddard/news/features/2010/pac-man-m... Credit: NASA/JPL/Goddard/SWRI/SSI NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Deployable Mini-Payload Missions Enabled by Small Radioisotope Power Systems (RPSs)

NASA Technical Reports Server (NTRS)

Abelson, Robert D.; Satter, Celeste M.

2005-01-01

Deployable mini-payloads are envisioned as small, simple, standalone instruments that could be deployed from a mother vehicle such as a rover or the proposed Jupiter Icy Moons Orbiter to key points of interest within the solar system. Used in conjunction with a small radioisotope power system (RPS), these payloads could potentially be used for long-duration science missions or as positional beacons for rovers or other spacecraft. The RPS power source would be suitable for deployable mini-payload missions that would take place anywhere there is limited, intermittent, or no solar insolation. This paper introduces two such concepts: (1) a seismic monitoring station deployed by a rover or aerobot, and (2) a passive fields and particles station delivered by a mother spacecraft to Jupiter.

TRAPPIST-1 Compared to Jovian Moons and Inner Solar System - Updated Feb. 2018

NASA Image and Video Library

2018-02-05

All seven planets discovered in orbit around the red dwarf star TRAPPIST-1 could easily fit inside the orbit of Mercury, the innermost planet of our solar system. In fact, they would have room to spare. TRAPPIST-1 also is only a fraction of the size of our Sun; it isn't much larger than Jupiter. So, the TRAPPIST-1 system's proportions look more like Jupiter and its moons than those of our solar system. The seven planets of TRAPPIST-1 are all Earth-sized and terrestrial. TRAPPIST-1 is an ultra-cool dwarf star in the constellation Aquarius, and its planets orbit very close to it. https://photojournal.jpl.nasa.gov/catalog/PIA22096

Europa Science Platforms and Kinetic Energy Probes

NASA Technical Reports Server (NTRS)

Hays, C. C.; Klein, G. A.

2003-01-01

This presentation will outline a proposed mission for the Jupiter Icy Moons Orbiter (JIMO). The mission outlined will concentrate on an examination of Europa. Some of the primary science goals for the JIMO mission are: 1) to answer broad science questions, 2) improved knowledge of Jovian system; specifically, lunar geological and geophysical properties, 3) chemical composition of Jovian lunar surfaces and subterranean matter, and 4) the search for life. In order to address these issues, the experiment proposed here will deploy orbiting, surface, and subterranean science platforms.

Exploring medium gravity icy planetary bodies: an opportunity in the Inner System by landing at Ceres high latitudes

NASA Astrophysics Data System (ADS)

Poncy, J.; Grasset, O.; Martinot, V.; Tobie, G.

2009-04-01

With potentially up to 25% of its mass as H2O and current indications of a differentiated morphology, 950km-wide "dwarf planet" Ceres is holding the promise to be our closest significant icy planetary body. Ceres is within easier reach than the icy moons, allowing for the use of solar arrays and not lying inside the deep gravity well of a giant planet. As such, it would represent an ideal step stone for future in-situ exploration of other airless icy bodies of major interest such as Europa or Enceladus. But when NASA's Dawn orbits Ceres and maps it in 2015, will we be ready to undertake the next logical step: landing? Ceres' gravity at its poles, at about one fifth of the Moon's gravity, is too large for rendezvous-like asteroid landing techniques to apply. Instead, we are there fully in the application domain of soft precision landing techniques such as the ones being developed for ESA's MoonNext mission. These latter require a spacecraft architecture akin to robotic lunar Landers or NASA's Phoenix, and differing from missions to comets and asteroids. If Dawn confirms the icy nature of Ceres under its regolith-covered surface, the potential presence of some ice spots on the surface would call for specific attention. Such spots would indeed be highly interesting landing sites. They are more likely to lie close to the poles of Ceres where cold temperatures should prevent exposed ice from sublimating and/or may limit the thickness of the regolith layer. Also the science and instruments suite should be fitted to study a large body that has probably been or may still be geologically active: its non-negligible gravity field combined with its high volatile mass fraction would then bring Ceres closer in morphology and history to an "Enceladus" or a frozen or near-frozen "Europa" than to a rubble-pile-structured asteroid or a comet nucleus. Thales Alenia Space and the "Laboratoire de Planétologie et Géodynamique" of the University of Nantes have carried out a preliminary

Towards a Global Unified Model of Europa's Tenuous Atmosphere

NASA Astrophysics Data System (ADS)

Plainaki, Christina; Cassidy, Tim A.; Shematovich, Valery I.; Milillo, Anna; Wurz, Peter; Vorburger, Audrey; Roth, Lorenz; Galli, André; Rubin, Martin; Blöcker, Aljona; Brandt, Pontus C.; Crary, Frank; Dandouras, Iannis; Jia, Xianzhe; Grassi, Davide; Hartogh, Paul; Lucchetti, Alice; McGrath, Melissa; Mangano, Valeria; Mura, Alessandro; Orsini, Stefano; Paranicas, Chris; Radioti, Aikaterini; Retherford, Kurt D.; Saur, Joachim; Teolis, Ben

2018-02-01

Despite the numerous modeling efforts of the past, our knowledge on the radiation-induced physical and chemical processes in Europa's tenuous atmosphere and on the exchange of material between the moon's surface and Jupiter's magnetosphere remains limited. In lack of an adequate number of in situ observations, the existence of a wide variety of models based on different scenarios and considerations has resulted in a fragmentary understanding of the interactions of the magnetospheric ion population with both the moon's icy surface and neutral gas envelope. Models show large discrepancy in the source and loss rates of the different constituents as well as in the determination of the spatial distribution of the atmosphere and its variation with time. The existence of several models based on very different approaches highlights the need of a detailed comparison among them with the final goal of developing a unified model of Europa's tenuous atmosphere. The availability to the science community of such a model could be of particular interest in view of the planning of the future mission observations (e.g., ESA's JUpiter ICy moons Explorer (JUICE) mission, and NASA's Europa Clipper mission). We review the existing models of Europa's tenuous atmosphere and discuss each of their derived characteristics of the neutral environment. We also discuss discrepancies among different models and the assumptions of the plasma environment in the vicinity of Europa. A summary of the existing observations of both the neutral and the plasma environments at Europa is also presented. The characteristics of a global unified model of the tenuous atmosphere are, then, discussed. Finally, we identify needed future experimental work in laboratories and propose some suitable observation strategies for upcoming missions.

Phase behavior and thermodynamic modeling of ices - implications for the geophysics of icy satellites. (Invited)

NASA Astrophysics Data System (ADS)

Choukroun, M.

2010-12-01

Ground-based observations and space missions to the outer Solar System (Voyager, Galileo, Cassini-Huygens) have evidenced recent geologic activity on many satellites of the giant planets. The diversity in surface expression of these icy moons’ activity is striking: from a scarred and young surface on Europa,1 with hydrated salts that may originate from a liquid layer buried at depth,2 to the South Polar plumes of Enceladus,3 where water ice particles are expelled along with a myriad of more complex molecules,4 to Titan, largest satellite of Saturn, with a dense atmosphere and a hydrocarbon cycle similar to the hydrological cycle on Earth.5 Large icy moons, i.e. with a radius greater than 500 km, share two particularities: a high content in water (on the order of a 30-70% bulk composition), and an interior segregated between a water-dominated mantle and a silicate-dominated core. The many forms water may have beneath the surface (ice polymorphs, liquid, hydrated compounds) bear a crucial role in the detected or alleged activity, and in the potential for astrobiological relevance. Indeed, any endogenic activity can only be approached through geophysical modelling of the internal structure and the thermal evolution. Current internal structure models for the icy moonse.g.,6 rely mainly on the contribution of each internal layer to the moment of inertia, generating non-unique solutions due to the large variability in density of H2O-bearing phases. Thermal evolution models,e.g.,7 can help constrain further the internal structure and geophysical activity, by starting with a given initial composition and state and investigating the thickening of icy layers through time. However, such models require both observational datasets and a precise description, as a function of pressure, temperature, and composition, of the thermophysical properties of the individual layers. Over the past century, experimental studies have provided a comprehensive view of the phase diagram of

ICI Showcase House Prototype

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

None

2009-02-16

Building Science Corporation collaborated with ICI Homes in Daytona Beach, FL on a 2008 prototype Showcase House that demonstrates the energy efficiency and durability upgrades that ICI currently promotes through its in-house efficiency program called EFactor.

Fuel-Optimal Trajectories in a Planet-Moon Environment Using Multiple Gravity Assists

NASA Technical Reports Server (NTRS)

Ross, Shane D.; Grover, Piyush

2007-01-01

For low energy spacecraft trajectories such as multi-moon orbiters for the Jupiter system, multiple gravity assists by moons could be used in conjunction with ballistic capture to drastically decrease fuel usage. In this paper, we outline a procedure to obtain a family of zero-fuel multi-moon orbiter trajectories, using a family of Keplerian maps derived by the first author previously. The maps capture well the dynamics of the full equations of motion; the phase space contains a connected chaotic zone where intersections between unstable resonant orbit manifolds provide the template for lanes of fast migration between orbits of different semimajor axes. Patched three body approach is used and the four body problem is broken down into two three-body problems, and the search space is considerably reduced by the use of properties of the Keplerian maps. We also introduce the notion of Switching Region where the perturbations due to the two perturbing moons are of comparable strength, and which separates the domains of applicability of the corresponding two Keplerian maps.

Infrared Spectral Studies of the Thermally-Driven Chemistry Present on Icy Satellites

NASA Technical Reports Server (NTRS)

Loeffler, Mark J.; Hudson, Reggie L.

2012-01-01

Remote sensing of Jupiters icy satellites has revealed that even though their surfaces arc composed mostly of water ice, molecules such as SO2, CO2, H2O2. O2, and O3 also are present. On Europa, a high radiation flux is believed to play a role in the formation of many of the minor species detected, and numerous laboratory studies have been devoted to explore this hypothesis. In this presentation we will discuss some of our recent research on another alteration pathway, thermally-driven chemical reactions, which are also important for understanding the chemical evolution of Europa's surface and sub-surface ices. We will focus on the infrared spectra of and reactions between H2O, SO2 and H2O2, at 80 - 130 K.

JUICE: a European mission to the Jovian system

NASA Astrophysics Data System (ADS)

Titov, Dmitrij; Dougherty, Michele K.; Wahlund, Jan-Erik; Barabash, Stas; Palumbo, Pasquale; Iess, Luciano; Piccioni, Giuseppe; Hussmann, Hauke; Langevin, Yves; Jaumann, Ralf; Altobelli, Nicolas; Fletcher, Leigh; Gurvits, Leonid; Gladstone, Randy; Erd, Christian; Hartogh, Paul; Bruzz, Lorenzo

JUpiter ICy moons Explorer (JUICE) will perform detailed investigations of Jupiter and its system with particular emphasis on Ganymede as a planetary body and potential habitat. The overarching theme for JUICE is: The emergence of habitable worlds around gas giants. At Ganymede, the mission will characterize in detail the ocean layers; provide topographical, geological and compositional mapping of the surface; study the physical properties of the icy crusts; characterize the internal mass distribution, investigate the exosphere; study Ganymede’s intrinsic magnetic field and its interactions with the Jovian magnetosphere. For Europa, the focus will be on the non-ice chemistry, understanding the formation of surface features and subsurface sounding of the icy crust over recently active regions. Callisto will be explored as a witness of the early solar system. JUICE will perform a multidisciplinary investigation of the Jupiter system as an archetype for gas giants. The circulation, meteorology, chemistry and structure of the Jovian atmosphere will be studied from the cloud tops to the thermosphere. The focus in Jupiter’s magnetosphere will include an investigation of the three dimensional properties of the magnetodisc and in-depth study of the coupling processes within the magnetosphere, ionosphere and thermosphere. Aurora and radio emissions will be elucidated. JUICE will study the moons’ interactions with the magnetosphere, gravitational coupling and long-term tidal evolution of the Galilean satellites. JUICE highly capable scientific payload includes 10 state-of-the-art instruments onboard the spacecraft plus one experiment that uses the spacecraft telecommunication system with ground-based radio telescopes. The remote sensing package includes a high-resolution multi-band visible imager (JANUS) and spectro-imaging capabilities from the ultraviolet to the sub-millimetre wavelengths (MAJIS, UVS, SWI). A geophysical package consists of a laser altimeter (GALA

Multi-Wavelength investigation of the co-orbital moons Dione and Helene

NASA Astrophysics Data System (ADS)

Royer, Emilie M.; Hendrix, Amanda R.; Howett, Carly; Spilker, Linda

2017-10-01

The icy satellites Dione and Helene share the same orbit, at 6.26 Saturn radii from the giant planet, which is within Saturn’s diffuse E ring. Helene is one of Dione’s two Trojan moons, located in the leading Lagrangian point L4 of Dione’s orbit. We present here preliminary results on the investigation of the Dione-Helene duo in term of origin, formation and evolution. Specifically, the key objectives are to retrieve the photometric properties and composition of the moons to answer questions such as: Are the Dione and Helene surfaces made of the same material? Did they form in the same region of the Solar System? Is one satellite older than the other? Have they experienced the same amount of space weathering?To provide the most complete evaluation of the Dione and Helene surfaces and advance our understanding of how exogenic processes affect the surfaces of icy satellites we use the synergy of four of the Cassini instruments: UVIS (Ultraviolet Imaging Spectrograph), ISS (Imaging Science Subsystem), VIMS (Visual and Infrared Mapping Spectrometer) and CIRS (Composite Infrared Spectrometer). Composite disk-integrated spectra of both moons have been produced to conduct spectral modeling over a large wavelength range from the ultraviolet to the infrared, from 111nm to 1mm. Until now, most investigations have focused only on one wavelength domain, telling only part of the story. A multi-wavelength analysis allows an in-depth investigation of the surfaces of the Saturnian satellites as each wavelength probes a different layer of the surface. Special attention is directed toward the search for correlations of basic properties (albedo, scattering properties, texture, grain size, composition, porosity, thermal properties) between Dione and Helene.

Geochemistry of Enceladus and the Galilean Moons from in situ Analysis of Ejecta

NASA Astrophysics Data System (ADS)

Postberg, F.; Schmidt, J.; Hillier, J. K.; Kempf, S.; Srama, R.

2012-09-01

The contribution of Cassini's dust detector CDA in revealing subsurface liquid water on Enceladus has demonstrated how questions in planetary science can be addressed by in situ analyses of icy dust particles. As the measurements are particularly sensitive to non-ice compounds embedded in an ice matrix, concentrations of various salts and organic compounds can be identified in different dust populations. This has successfully been demonstrated at Enceladus, giving insights in the moons subsurface geochemistry. This method can be applied to any planetary body that ejects particles to distances suitable for spacecraft sensing. The Galilean moons are of particular relevance since they are believed to steadily emit grains from their surfaces either by active volcanism (Io) or stimulated by micrometeoroid bombardment (Europa, Ganymede, Callisto).

Jupiter and the Extrasolar Giant Planets: Composition and origin of atmospheres

NASA Astrophysics Data System (ADS)

Atreya, S.; Wong, A.; Mahaffy, P.; Niemann, H.; Wong, M.; Owen, T.

In this paper, we will discuss the related issues of the composition and origin of Jupiter's atmosphere, and how this can help in understanding the atmospheres of the extrasolar giant planets (EGP). In the case of Jupiter, a wealth of data on the planet's atmosphere is available, largely as a result of the successful spacecraft observations by the Galileo Orbiter and Probe, ISO and Voyager, complemented by ground-based observations (Atreya et al., PSS 47, 1243, 1999; Encrenaz et al., PSS, 47, 1223, 1999; Atreya et al., PSS, 2002, in press). Although the atmosphere is made up of mostly H and He, trace amounts of CH4 and its products, H O, NH 3, H2S,22 heavy noble gases (Ne, Ar, Kr, Xe), and disequilibrium species (PH3, CO, CO2, GeH4, AsH3), are also detected. From measurements of the trace constituents in Jupiter's upper and the deep well-mixed troposphere by the Galileo Probe, it has been possible to determine the "bulk" abundance of the heavy elements, which is key to understanding the origin and evolution of the planet's atmosphere. C, N, S, Ar, Kr and Xe are all found to be enriched by a factor of 2-4 relative to their solar ratios to H. This unexpected finding led Owen et al. (Nature, 402, 269, 1999) to suggest that the icy planetesimals that formed Jupiter must have had a low temperature (=30 K) origin in order for them to trap the volatiles containing the heavy elements. An alternate hypothesis - according to which the volatiles were trapped in clathrate hydrates instead (Gautier et al., Ap. J., 550, L227, 2001) - overestimates Jupiter's sulfur abundance, and it too requires a remarkably low temperature of =38 K for argon clathration (Gautier et al., Ap. J., 559, L183, 2001) Could the known composition of Jupiter help in understanding the atmospheres of the EGP's? So far, only sodium has been detected in the atmosphere of an EGP that orbits a sun-like star, HD 209458, at 0.0468 AU (Charbonneau et al., Ap. J., 568, 377, 2002). However, sodium has not been

Power Processing for a Conceptual Project Prometheus Electric Propulsion System

NASA Technical Reports Server (NTRS)

Scina, Joseph E., Jr.; Aulisio, Michael; Gerber, Scott S.; Hewitt, Frank; Miller, Leonard; Elbuluk, Malik; Pinero, Luis R. (Technical Monitor)

2005-01-01

NASA has proposed a bold mission to orbit and explore the moons of Jupiter. This mission, known as the Jupiter Icy Moons Orbiter (JIMO), would significantly increase NASA s capability to explore deep space by making use of high power electric propulsion. One electric propulsion option under study for JIMO is an ion propulsion system. An early version of an ion propulsion system was successfully used on NASA's Deep Space 1 mission. One concept for an ion thruster system capable of meeting the current JIMO mission requirement would have individual thrusters that are 16 to 25 kW each and require voltages as high as 8.0 kV. The purpose of this work is to develop power processing schemes for delivering the high voltage power to the spacecraft ion thrusters based upon a three-phase AC distribution system. In addition, a proposed DC-DC converter topology is presented for an ion thruster ancillary supply based upon a DC distribution system. All specifications discussed in this paper are for design convenience and are speculative in nature.

The formation of jupiter, the jovian early bombardment and the delivery of water to the asteroid belt: the case of (4) vesta.

PubMed

Turrini, Diego; Svetsov, Vladimir

2014-01-28

The asteroid (4) Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and collisional evolution of Vesta. In particular, we argue that the observational data are best reproduced if the bulk of the impactors was represented by 1-2 km wide planetesimals and if Jupiter underwent a limited (a fraction of au) displacement.

The Formation of Jupiter, the Jovian Early Bombardment and the Delivery of Water to the Asteroid Belt: The Case of (4) Vesta

PubMed Central

Turrini, Diego; Svetsov, Vladimir

2014-01-01

The asteroid (4) Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and collisional evolution of Vesta. In particular, we argue that the observational data are best reproduced if the bulk of the impactors was represented by 1–2 km wide planetesimals and if Jupiter underwent a limited (a fraction of au) displacement. PMID:25370027

Multi-layer hydrostatic equilibrium of planets and synchronous moons: theory and application to Ceres and to solar system moons

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

Tricarico, Pasquale

2014-02-20

The hydrostatic equilibrium of multi-layer bodies lacks a satisfactory theoretical treatment despite its wide range of applicability. Here we show that by using the exact analytical potential of homogeneous ellipsoids we can obtain recursive analytical solutions and an exact numerical method for the hydrostatic equilibrium shape problem of multi-layer planets and synchronous moons. The recursive solutions rely on the series expansion of the potential in terms of the polar and equatorial shape eccentricities, while the numerical method uses the exact potential expression. These solutions can be used to infer the interior structure of planets and synchronous moons from their observedmore » shape, rotation, and gravity. When applied to the dwarf planet Ceres, we show that it is most likely a differentiated body with an icy crust of equatorial thickness 30-90 km and a rocky core of density 2.4-3.1 g cm{sup –3}. For synchronous moons, we show that the J {sub 2}/C {sub 22} ≅ 10/3 and the (b – c)/(a – c) ≅ 1/4 ratios have significant corrections of order Ω{sup 2}/(πGρ), with important implications for how their gravitational coefficients are determined from fly-by radio science data and for how we assess their hydrostatic equilibrium state.« less

Interaction of Jovian energetic particles with moons and gas tori based on recent Juno/JEDI data

NASA Astrophysics Data System (ADS)

Kollmann, P.; Mauk, B.; Clark, G. B.; Paranicas, C.; Haggerty, D. K.; Rymer, A. M.; Bolton, S. J.; Connerney, J. E. P.; Levin, S.

2016-12-01

Juno is the first spacecraft in a polar orbit around Jupiter. It entered orbit in July 2016, will deliver the first science data from near Jupiter at the end of August, and pass very close to Jupiter 4 more times by December. We will use data from the three JEDI instruments onboard that measure ions and electrons in the tens of keV to MeV range while discriminating among ion species. Recording of the full energy and time-of-flight information of a subset of the detected particles will allow distinguishing foreground from contaminating background in many cases. Since Juno will be mostly at high latitudes, the JEDI measurements will differ from the measurements of previous missions that were mostly in the equatorial plane. The increasingly strong radiation environment inwards of Europa's orbit caused contamination and/or dead time effects in many of the previously flown particle instruments, which made it difficult to study this region with the existing data. We expect that Juno's unique orbit and the JEDI design will largely avoid these problems. During one hour of closest approach, Juno will be on magnetic field lines that map within the orbits of the Galilean moons. We will study the data in this region and analyze the intensity dropouts that are caused by the interaction between the particles that bounce along field lines and drift around the planet with the moons and associated gas and plasma tori. Also, we will analyze the rate of intensity change towards Jupiter that is determined by radial transport, potential local source processes, and the range of pitch angles that can reach the changing latitudes.

Evidence for a Trapped Radical (OH) on Ariel, Oberon, and Titania from Hubble Space Telescope Ultraviolet Spectra

NASA Technical Reports Server (NTRS)

Roush, Ted L.; Noll, Keith S.; Pendleton, Yvonne J.; DeVincenzi, Donald (Technical Monitor)

2000-01-01

The moons Ariel, Titania, and Oberon have orbits lying within the magnetosphere of Uranus, exposing them to particle irradiation from trapped Ions. This Is similar to the situation experienced by the jovian moons Europa, Ganymede, and Callisto, as well as the saturnian satellites Enceladus, Tethys, Dione, and Rhea. Identification of SO2 on Europa, Ganymede and Callisto, and O3 on Ganymede, Rhea, and Dione has supported suggestions that chemical modifications occur on icy bodies due to ion bombardment associated with the particles entrained within the magnetospheric fields of Jupiter and Saturn. Similar to the Jovian and saturnian satellites mentioned above, water ice is a major component on the larger uranian satellites", thus one might anticipate chemical modification to he an important process in the uranian system. Laboratory studies or the interaction of ultraviolet (uv) and charged-particle radiation with water ice show that in addition to molecular species, a variety of radicals are also produced. We report here evidence for an uv absorption feature in the spectra of Ariel, Titania, and Oberon that we identify as due, in part, to OH; providing the first evidence of a radical produced and trapped on an icy moon within our solar system.

TRAPPIST-1 Comparison to Solar System and Jovian Moons

NASA Image and Video Library

2017-02-22

All seven planets discovered in orbit around the red dwarf star TRAPPIST-1 could easily fit inside the orbit of Mercury, the innermost planet of our solar system. In fact, they would have room to spare. TRAPPIST-1 also is only a fraction of the size of our sun; it isn't much larger than Jupiter. So the TRAPPIST-1 system's proportions look more like Jupiter and its moons than those of our solar system. 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. 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. http://photojournal.jpl.nasa.gov/catalog/PIA21428

A disk of scattered icy objects and the origin of Jupiter-family comets.

PubMed

Duncan, M J; Levison, H F

1997-06-13

Orbital integrations carried out for 4 billion years produced a disk of scattered objects beyond the orbit of Neptune. Objects in this disk can be distinguished from Kuiper belt objects by a greater range of eccentricities and inclinations. This disk was formed in the simulations by encounters with Neptune during the early evolution of the outer solar system. After particles first encountered Neptune, the simulations show that about 1 percent of the particles survive in this disk for the age of the solar system. A disk currently containing as few as approximately 6 x 10(8) objects could supply all of the observed Jupiter-family comets. Two recently discovered objects, 1996 RQ20 and 1996 TL66, have orbital elements similar to those predicted for objects in this disk, suggesting that they are thus far the only members of this disk to be identified.

ICI/BASF PP for acrylics swap

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

Alperowicz, N.

ICI (London) and BASF (Ludwigshafen) have announced their long-awaited polypropylene (PP) for acrylics swap deal. ICI is buying BASF's European acrylic resin business, and the German firm will acquire ICI's European PP operations. The deal is due for completion by mid-1993, subject to regulatory approvals. BASF, hitherto a small-scale PP producer, doubles capacity to 600,000 m.t./year and moves up the European PP league to number three, behind Himont and Shell. BASF, whose process is used in the plants, secures a foothold in the UK PP market, where Shell - planning a merger with Himont - is the only other producer,more » with 170,000 m.t./year. ICI's purchase involves BASF's Resart GmbH and Critesa SA subsidiaries, located at Mainz, Germany and near Barcelona, Spain, respectively. The business - which will add about [Brit pounds]60 million ($93 million) to ICI Acrylics [Brit pounds]300-million revenues - employs 400 people, who will transfer to ICI.« less

Strong ocean tidal flow and heating on moons of the outer planets.

PubMed

Tyler, Robert H

2008-12-11

Data from recent space missions have added strong support for the idea that there are liquid oceans on several moons of the outer planets, with Jupiter's moon Europa having received the most attention. But given the extremely cold surface temperatures and meagre radiogenic heat sources of these moons, it is still unclear how these oceans remain liquid. The prevailing conjecture is that these oceans are heated by tidal forces that flex the solid moon (rock plus ice) during its eccentric orbit, and that this heat entering the ocean does not rapidly escape because of the insulating layer of ice over the ocean surface. Here, however, I describe strong tidal dissipation (and heating) in the liquid oceans; I show that a subdominant and previously unconsidered tidal force due to obliquity (axial tilt of the moon with respect to its orbital plane) has the right form and frequency to resonantly excite large-amplitude Rossby waves in these oceans. In the specific case of Europa, the minimum kinetic energy of the flow associated with this resonance (7.3 x 10(18) J) is two thousand times larger than that of the flow excited by the dominant tidal forces, and dissipation of this energy seems large enough to be a primary ocean heat source.

Simulations of mechanical failure in ice: Implications of terrestrial fracture models as applied to they icy satellites of the outer solar system

NASA Astrophysics Data System (ADS)

Walker, C. C.; Bassis, J. N.

2011-12-01

At the South Pole of Enceladus, a small icy moon orbiting Saturn, is a heavily fractured ice plain surrounded by a nearly-circular mountain range. Remarkably, the Cassini orbiter detected jets of water emanating from the icy shell and into space, originating from 4 parallel "tiger stripe" rifts within the center of the ice plain. The tiger stripes imaged on Enceladus are morphologically similar to rifts observed to form under extensional stress regimes in terrestrial ice shelves; the putative subsurface ocean hypothesized beneath the icy shell strengthens the analogy that their formation may have similar mechanical origins. Past studies have also suggested that the tiger stripes are the result of a process similar to that of mid-ocean ridge spreading on the Earth, but it remains to be seen whether or not such motion is consistent with the mountainous features seen at the circular cliff-like boundary of the region. In an attempt to understand the formation of these tiger stripes and their relationship to the observed mountain chains, we apply a conceptual model in which the ice is considered to be less like a continuous fluid body and, instead, behaves like a granular material made up of discrete blocks of ice. The tidal forces on the small moon tug on the shell enough that it has been cracked many times over, motivating the assumption that the ice exists in a continuum between wholly intact ice and highly pre-fractured ice. We employ several experimental setups with the intention of mapping the deformation of the south polar segment of the shell, to determine the processes that may contribute to its observed morphological state. These setups range from large scale topographical models, e.g., simulating the build up of mountains and processes that lead to overall elevation differences in the region, to small-scale, and focus on the more detailed level of fracturing. We explore our ice-shelf rifting analogy by modeling both icy moon fracturing and ice shelf rifting

The Galilean Satellites

NASA Image and Video Library

1998-05-08

In this "family portrait," the four Galilean Satellites are shown to scale. These four largest moons of Jupiter shown in increasing distance from Jupiter are (left to right) Io, Europa, Ganymede, and Callisto. These global views show the side of volcanically active Io which always faces away from Jupiter, icy Europa, the Jupiter-facing side of Ganymede, and heavily cratered Callisto. The appearances of these neighboring satellites are amazingly different even though they are relatively close to Jupiter (350,000 kilometers for Io; 1, 800,000 kilometers for Callisto). These images were acquired on several orbits at very low "phase" angles (the sun, spacecraft, moon angle) so that the sun is illuminating the Jovian moons from completely behind the spacecraft, in the same way a full moon is viewed from Earth. The colors have been enhanced to bring out subtle color variations of surface features. North is to the top of all the images which were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. Io, which is slightly larger than Earth's moon, is the most colorful of the Galilean satellites. Its surface is covered by deposits from actively erupting volcanoes, hundreds of lava flows, and volcanic vents which are visible as small dark spots. Several of these volcanoes are very hot; at least one reached a temperature of 2000 degrees Celsius (3600 degrees Fahrenheit) in the summer of 1997. Prometheus, a volcano located slightly right of center on Io's image, was active during the Voyager flybys in 1979 and is still active as Galileo images were obtained. This global view was obtained in September 1996 when Galileo was 485,000 kilometers from Io; the finest details that can be discerned are about 10 km across. The bright, yellowish and white materials located at equatorial latitudes are believed to be composed of sulfur and sulfur dioxide. The polar caps are darker and covered by a redder material. Europa has a very different surface from its rocky

Ices on the Satellites of Jupiter, Saturn, and Uranus

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.; Brown, Robert H.; Calvin, Wendy M.; Roush, Ted L.

1995-01-01

Three satellites of Jupiter, seven satellites of Saturn, and five satellites of Uranus show spectroscopic evidence of H2O ice on their surfaces, although other details of their surfaces are highly diverse. The icy surfaces contain contaminants of unknown composition in varying degrees of concentration, resulting in coloration and large differences in albedo. In addition to H2O, Europa has frozen SO2, and Ganymede has O2 in the surface; in both of these cases external causes are implicated in the deposition or formation of these trace components. Variations in ice exposure across the surfaces of the satellites are measured from the spectroscopic signatures. While H2O ice occurs on the surfaces of many satellites, the range of bulk densities of these bodies shows that its contribution to their overall compositions is highly variable from one object to another.

Tidal Response of Preliminary Jupiter Model

NASA Astrophysics Data System (ADS)

Wahl, Sean M.; Hubbard, William B.; Militzer, Burkhard

2016-11-01

In anticipation of improved observational data for Jupiter’s gravitational field, from the Juno spacecraft, we predict the static tidal response for a variety of Jupiter interior models based on ab initio computer simulations of hydrogen-helium mixtures. We calculate hydrostatic-equilibrium gravity terms, using the non-perturbative concentric Maclaurin Spheroid method that eliminates lengthy expansions used in the theory of figures. Our method captures terms arising from the coupled tidal and rotational perturbations, which we find to be important for a rapidly rotating planet like Jupiter. Our predicted static tidal Love number, {k}2=0.5900, is ˜10% larger than previous estimates. The value is, as expected, highly correlated with the zonal harmonic coefficient J 2, and is thus nearly constant when plausible changes are made to the interior structure while holding J 2 fixed at the observed value. We note that the predicted static k 2 might change, due to Jupiter’s dynamical response to the Galilean moons, and find reasons to argue that the change may be detectable—although we do not present here a theory of dynamical tides for highly oblate Jovian planets. An accurate model of Jupiter’s tidal response will be essential for interpreting Juno observations and identifying tidal signals from effects of other interior dynamics of Jupiter’s gravitational field.

The Impact of a Large Object with Jupiter in July 2009

NASA Astrophysics Data System (ADS)

Sanchez-Lavega, Agustin; Wesley, A.; Orton, G.; Chodas, P.; Hueso, R.; Perez-Hoyos, S.; Fletcher, L.; Yanamandra-Fisher, P.; Legarreta, J.; Gomez-Forrellad, J. M.

2010-05-01

The only major impact ever observed directly in the Solar System was that of a large fragmented comet with Jupiter in July (1994) (Comet Shoemaker-Levy 9; SL9). We report here the observation of a second, single, large impact on Jupiter that occurred on 19 July 2009 at a latitude of -55° with an orthogonal entry trajectory and a lower incidence angle compared to those of SL9. The size of the initial aerosol cloud debris was 4,800 km East-West and 2,500 km North-South. Comparison its properties with those produced by the SL9 fragments, coupled with dynamical calculations of possible pre-impact orbits, indicates that the impactor was most probably an icy body with a size of 0.5-1 km. We calculate that the rate of collisions of this magnitude may be five to ten times more frequent than previously thought. The search for unpredicted impacts, such as the current one, could be best performed in the near-infrared methane absorption bands at 890 nm and in the 2.12 to 2.3 μm K methane-hydrogen absorption band, where the high-altitude aerosols detach by their brightness relative to Jupiter's primary clouds. We present measurements of the debris dispersion by Jovian winds from a long-term imaging campaign with ground-based telescopes. Ackowledgements: Work was supported by the Spanish MICIIN AYA2009-10701 with FEDER and Grupos Gobierno Vasco IT-464-07, by NASA funds to JPL, Caltech, by the NASA Postdoctoral Program at JPL, and by the Glasstone Fellowship program at Oxford.

Cassini radar and radiometry observations of Saturn's airless icy satellites

NASA Astrophysics Data System (ADS)

Le Gall, A. A.; West, R.; Janssen, M. A.; Leyrat, C.; Bonnefoy, L.; Lellouch, E.

2017-12-01

The Cassini Radar is a multimode microwave sensor operating in the Ku-band, at a wavelength of 2.2 cm. While it was initially designed to examine the surface of Titan through the veil of its optically-opaque atmosphere, it is occasionally used to observe airless Saturn's moons from long ranges (>50 000 km) and, less frequently, during targeted flybys. In its active mode, the instrument measures the surface reflectivity in the backscattering direction. In its passive mode - or radiometry mode - it records the microwave thermal emission from the near-surface (typically few meters). Doing so, it provides insights into the degree of purity and maturity of the water-ice regolith of the investigated objects. In particular, it can reveal hemispheric dichotomies or regional anomalies and satellite-to-satellite variabilities which give clues into what is common and what is specific to the history of each satellite and to the processes that have shaped their surface/subsurface. In this paper, we will give an overview of the Cassini radar/radiometry observations of Saturnian icy moons, most of which have not been published yet. Now that the mission has come to an end, we will describe how the radio investigation of these objects can be pursued from Earth-based radiotelescopes.

Laboratory studies on low-energy electron penetration depths into amorphous ice - consequence to astrobiology on icy surfaces

NASA Astrophysics Data System (ADS)

Gudipati, M. S.; Li, I.; Lignell, A. A.

2009-12-01

Penetration of electrons through icy surfaces plays an important role in radiation processing of solar system icy bodies. However, to date, there is no quantitative data available on the penetration depths of electrons through cryogenic water-ices. Penetration of high-energy incident electrons also results in the in-situ formation of secondary low-energy electrons, such as on the surface of Europa (Herring-Captain et al., 2005; Johnson et al., 2004). Low-energy electrons can also be produced through photoionization process such as on comet surfaces, or through bombardment by solar wind on icy surfaces (Bodewits et al., 2004). Present models use the laboratory penetration data of high-energy (>10 keV) electrons through silicon as a proxy for the ice (Cooper et al., 2001), normalized by the density of the medium. So far no laboratory studies have been conducted that deal with the penetration of electrons through amorphous or crystalline ices. In order to address this issue, we adopted a new experimental strategy by using aromatic molecules as probes. To begin with, we carried out systematic studies on the penetration depths of low-energy electrons (5 eV - 2 keV) through amorphous ice films of defined thickness at cryogenic temperatures (5 - 30 K). The results of these experiments will be analyzed and their relevance to survival of organic material on solar system icy surfaces will be presented. References: Bodewits, D., et al., 2004. X-ray and Far-Ultraviolet emission from comets: Relevant charge exchange processes. Physica Scripta. 70, C17-C20. Cooper, J. F., et al., 2001. Energetic ion and electron irradiation of the icy Galilean satellites. Icarus. 149, 133-159. Herring-Captain, J., et al., 2005. Low-energy (5-250 eV) electron-stimulated desorption of H+, H2+, and H+(H2O)nfrom low-temperature water ice surfaces. Physical Review B. 72, 035431-10. Johnson, R. E., et al., Radiation Effects on the Surfaces of the Galilean Satellites. In: F. Bagenal, et al., Eds

Plasma IMS Composition Measurements for Europa, Ganymede, and the Jovian System

NASA Technical Reports Server (NTRS)

Sittler, E. C., Jr.; Cooper, J. F.; Hartle, R. E.; Paterson, W. R.; Christian, E. R.; Lipatov, A. S.; Mahaffy, P R.; Paschalidis, N.; Sarantos, M.; Coplan, M. A.;

Plasma IMS Composition Measurements for Europa, Ganymede, and the Jovian Systems

NASA Technical Reports Server (NTRS)

Sittler, E.; Cooper, J.; Hartle, R.; Paterson ,W.; Christian, E.; Mahaffy, P.; Paschalidis, N.; Lipatov, A.; Sarantos, M.; Coplan, M.;

The 3GM Radio Science Experiment on board the ESA JUICE Mission

NASA Astrophysics Data System (ADS)

Di Benedetto, M.; Ciarcia, S., Sr.; Iess, L.; Kaspi, Y.; Mann, R., Sr.; Shapira, A., Sr.

2017-12-01

The JUpiter ICy moons Explorer (JUICE) is a mission of the European Space Agency devoted to the exploration of the Jupiter system. The main mission themes are the study of Jupiter as an archetype for gas giants and exoplanetary systems, and the characterisation of the potentially habitable worlds Europa, Ganymede and Callisto. During the Jovian tour, JUICE will encounter multiple times the moons Europa and Callisto, while its final target, Ganymede, will be thoroughly investigated in the last phase of the mission, when JUICE will enter orbiting around it. The spacecraft payload consists of a suite of ten instruments, comprising a remote sensing, a geophysical, and a plasma and waves in situ package, plus a radio science instrument, named 3GM (Gravity and Geophysics of Jupiter and the Galilean Moons). An additional experiment, having no dedicated onboard hardware, will be carried out using ground-based VLBI measurements. The 3GM instrument is made up of two separate and independent units incorporated in the spacecraft TT&C subsystem: a Ka band Transponder (KaT) and an Ultra Stable Oscillator (USO). The KaT will enable two-way range and range-rate measurements at Ka band (34.5-32.2 GHz), accurate respectively to 20 cm and 3 μm/s (at 1000 s integration time). The gravity experiment relies on the Ka band radio link to help unveiling the interior structure of Ganymede, inferring the extent of the subsurface global ocean through measurements of the moon's gravity field and tidal response. For Europa and Callisto, only the low degree gravity coefficients can be measured during flybys. 3GM will refine the moment of inertia of the two moons and will determine departures from the hydrostatic equilibrium. The USO will be used for one-way downlink occultation experiments. It will generate on board a highly stable 4.79 MHz reference signal with an Allan deviation of few parts of 10-13 at 1-1000 s integration time. Then the signal will be routed to the DST after an internal x12

Jupiter Eruptions

NASA Technical Reports Server (NTRS)

2008-01-01

[figure removed for brevity, see original site] Click on the image for high resolution image of Nature Cover

Detailed analysis of two continent-sized storms that erupted in Jupiter's atmosphere in March 2007 shows that Jupiter's internal heat plays a significant role in generating atmospheric disturbances. Understanding these outbreaks could be the key to unlock the mysteries buried in the deep Jovian atmosphere, say astronomers.

This visible-light image is from NASA's Hubble Space Telescope taken on May 11, 2007. It shows the turbulent pattern generated by the two plumes on the upper left part of Jupiter.

Understanding these phenomena is important for Earth's meteorology where storms are present everywhere and jet streams dominate the atmospheric circulation. Jupiter is a natural laboratory where atmospheric scientists study the nature and interplay of the intense jets and severe atmospheric phenomena.

According to the analysis, the bright plumes were storm systems triggered in Jupiter's deep water clouds that moved upward in the atmosphere vi gorously and injected a fresh mixture of ammonia ice and water about 20 miles (30 kilometers) above the visible clouds. The storms moved in the peak of a jet stream in Jupiter's atmosphere at 375 miles per hour (600 kilometers per hour). Models of the disturbance indicate that the jet stream extends deep in the buried atmosphere of Jupiter, more than 60 miles (approximately100 kilometers) below the cloud tops where most sunlight is absorbed.

Main methods of trajectory synthesis for scenarios of space missions with gravity assist maneuvers in the system of Jupiter and with landing on one of its satellites

NASA Astrophysics Data System (ADS)

Golubev, Yu. F.; Tuchin, A. G.; Grushevskii, A. V.; Koryanov, V. V.; Tuchin, D. A.; Morskoy, I. M.; Simonov, A. V.; Dobrovolskii, V. S.

2016-12-01

The development of a methodology for designing trajectories of spacecraft intended for the contact and remote studies of Jupiter and its natural satellites is considered. This methodology should take into account a number of specific features. Firstly, in order to maintain the propellant consumption at an acceptable level, the flight profile, ensuring the injection of the spacecraft into orbit around the Jovian moon, should include a large number of gravity assist maneuvers both in the interplanetary phase of the Earth-to-Jupiter flight and during the flight in the system of the giant planet. Secondly, the presence of Jupiter's powerful radiation belts also imposes fairly strict limitations on the trajectory parameters.

The New Horizons Mission to Pluto and Flyby of Jupiter

NASA Technical Reports Server (NTRS)

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

Using the tools of the trade to understand plasma interactions at Jupiter and Saturn

NASA Astrophysics Data System (ADS)

Kivelson, Margaret G.

2017-10-01

For more than half a century, we have been learning how magnetospheres work. Fluid motions and electromagnetic interactions combine to produce the plasma and field environment of a planet. Kinetic responses often control the dynamics. Initial descriptions of the terrestrial magnetosphere were often theoretical (e.g., Chapman and Ferraro, Dungey) before an explosion of spacecraft data provided an atlas of the system and its temporal variations. The basic structure and dynamics of the terrestrial magnetosphere are now largely understood. A different situation exists for the magnetospheres of Jupiter, Saturn, and their moons. Data acquired from spacecraft flybys or from orbit have characterized many aspects of these systems, but measurements are far more limited than at Earth both in space and in time. Even after Cassini’s mission to Saturn and Juno’s prime mission at Jupiter have ended, large regions in the plasma environments of these planets will remain unexplored. No monitors are available to characterize the upstream solar wind. Theory is challenged by the complexity introduced by dynamical effects of the planets’ rapid rotation and the unfamiliar parameter regimes governing interactions with their large moons. Simulation has come to the rescue, providing computational models designed to incorporate the effects of rotation or to describe moon-magnetosphere interactions. Yet simulations must be viewed with appropriate skepticism as they invariably require some compromise with reality. This talk will describe a symbiotic approach to understanding the dynamics of giant planet magnetospheres and the plasma interactions between magnetospheric plasma and large moons. Data acquired along a spacecraft trajectory are compared with values extracted from a virtual spacecraft moving through the same path in the simulation. If results are similar, we use the simulation to identify the processes responsible for puzzling aspects of the signatures. If results differ

400th Anniversary of Marius's Book with the First Image of an Astronomical Telescope and of Orbits of Jovian Moons

NASA Astrophysics Data System (ADS)

Pasachoff, Jay M.; Leich, Pierre

2015-01-01

Simon Mayr's (Marius's) Mundus Iovialis Anno M·DC·IX Detectus Ope Perspicilli Belgici (The World of Jupiter...) was published in Nuremberg in 1614; Marius was the Ansbach court mathematician. The frontispiece includes not only a portrait of Marius (1573-1624) himself but also, in the foreground, a long tube labelled "perspicillum," the first known image of a telescopic device used for astronomy; the name "telescope" came later. A schematic diagram of Jupiter with four moons orbiting appears at upper left; Marius, following a suggestion from Kepler, gave these Galilean satellites the names now still in use: Io, Europa. Ganymede, and Callisto. The title continues Hoc est, Quatuor Joviali cum Planetarum, cum Theoria, tum Tabulae, Propriis Observationibus Maxime Fundate.... A pair of conferences was held in Germany in 2014 to commemorate the 400th anniversary of Marius's book and to discuss Marius's work and its relation to Galileo's work (http://www.simon-marius.net; http://www.simon-marius.net/index.php?lang=en&menu=1 28 languages are available). Marius (Mayr) had independently discovered the four satellites of Jupiter, apparently one day after Galileo, on December 29 O.S., 1609; by the time he published his work four years later (a local-circulation publication had appeared in Nuremberg in 1611 in Prognosticon Astrologicum auf das Jahr 1612), Galileo had gained fame and priority, and Galileo accused Marius of plagiarism in Il Saggiatore (1623). With his Belgian telescope, Marius also noted the tilt of the orbital plane of Jupiter's moons, sunspots (1611), and the Andromeda Nebula (1612). He claimed to have worked out a system of cosmology similar to the Tychonic system in 1596, contemporaneously to Kepler's Mysterium Cosmographicum. A crater, the Marius Hills, and the Rima Marius on the Moon are named for him by the I.A.U., as well as, to celebrate the quadricentennial, a main-belt asteroid, now (7984) Marius. Acknowledgment: JMP thanks Seth Fagen, PRPH Books in

A Jupiter Ganymede Orbiter for the EJSM mission: the JGO assessment phase study by the Thales Alenia Space consortium

NASA Astrophysics Data System (ADS)

Poncy, Joel; Couzin, Patrice; Mercier, Manuel; Boschetti, Demis

2010-05-01

ESA and NASA have undertaken advanced studies of a common mission to Jupiter's system, EJSM (Europa Jupiter System Mission). This mission comprises two spacecrafts launched independently in 2020 and reaching the system in 2026. This is a one-in-a-generation opportunity for Europe to contribute significantly to the science of this part of the Solar System, and as such, all efforts shall subsequently be made to maximize the scientific return without jeopardizing the technical and programmatic feasibility of the mission. A sub-glacial ocean on Europa and potentially two others on Ganymede and Callisto, the monitoring of Io's volcanic activity, the upper atmosphere of Jupiter, its rings, its tens of irregular moons, the tides, the magnetic fields of Jupiter and Ganymede and the behaviour of the plasma, the list of science objectives is not only impressive but also generates enthusiasm in the mission. In this NASA-ESA joint mission, NASA will take charge of both Io and Europa with the Jupiter Europa Orbiter (JEO). Europe will get a fascinating share with the Jupiter Ganymede Orbiter (JGO), which will achieve the close study of the two largest and outermost Galilean moons Ganymede and Callisto and in addition, at-a-distance, the observation of the other targets mentioned above. ESA has awarded three industrial contracts for an assessment phase of JGO. As leader of one of the consortia, Thales Alenia Space is proud to present in this poster its achievements on this exciting mission. The requirements are discussed and the mission drivers identified. The main trades and the resulting architecture are recalled, along with the main selection drivers. The major system interrelated trades have covered the launcher and propulsion type, the number of regulated phases, the strategy for communications and science timeline, the need for HGA pointing, the sizing and configuration of the Solar Array, the accommodation of external appendages, the accommodation of the payload, the

Crustal control of dissipative ocean tides in Enceladus and other icy moons

NASA Astrophysics Data System (ADS)

Beuthe, Mikael

2016-12-01

Could tidal dissipation within Enceladus' subsurface ocean account for the observed heat flow? Earthlike models of dynamical tides give no definitive answer because they neglect the influence of the crust. I propose here the first model of dissipative tides in a subsurface ocean, by combining the Laplace Tidal Equations with the membrane approach. For the first time, it is possible to compute tidal dissipation rates within the crust, ocean, and mantle in one go. I show that oceanic dissipation is strongly reduced by the crustal constraint, and thus contributes little to Enceladus' present heat budget. Tidal resonances could have played a role in a forming or freezing ocean less than 100 m deep. The model is general: it applies to all icy satellites with a thin crust and a shallow ocean. Scaling rules relate the resonances and dissipation rate of a subsurface ocean to the ones of a surface ocean. If the ocean has low viscosity, the westward obliquity tide does not move the crust. Therefore, crustal dissipation due to dynamical obliquity tides can differ from the static prediction by up to a factor of two.

REFLECTED LIGHT CURVES, SPHERICAL AND BOND ALBEDOS OF JUPITER- AND SATURN-LIKE EXOPLANETS

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

Dyudina, Ulyana; Kopparla, Pushkar; Ingersoll, Andrew P.

Reflected light curves observed for exoplanets indicate that a few of them host bright clouds. We estimate how the light curve and total stellar heating of a planet depends on forward and backward scattering in the clouds based on Pioneer and Cassini spacecraft images of Jupiter and Saturn. We fit analytical functions to the local reflected brightnesses of Jupiter and Saturn depending on the planet’s phase. These observations cover broadbands at 0.59–0.72 and 0.39–0.5 μ m, and narrowbands at 0.938 (atmospheric window), 0.889 (CH4 absorption band), and 0.24–0.28 μ m. We simulate the images of the planets with a ray-tracingmore » model, and disk-integrate them to produce the full-orbit light curves. For Jupiter, we also fit the modeled light curves to the observed full-disk brightness. We derive spherical albedos for Jupiter and Saturn, and for planets with Lambertian and Rayleigh-scattering atmospheres. Jupiter-like atmospheres can produce light curves that are a factor of two fainter at half-phase than the Lambertian planet, given the same geometric albedo at transit. The spherical albedo is typically lower than for a Lambertian planet by up to a factor of ∼1.5. The Lambertian assumption will underestimate the absorption of the stellar light and the equilibrium temperature of the planetary atmosphere. We also compare our light curves with the light curves of solid bodies: the moons Enceladus and Callisto. Their strong backscattering peak within a few degrees of opposition (secondary eclipse) can lead to an even stronger underestimate of the stellar heating.« less

Low Force Icy Regolith Penetration Technology

NASA Technical Reports Server (NTRS)

Metzger, P. T.; Galloway, G. M.; Mantovani, J. G.; Zacny, K.; Zacny, Kris; Craft, Jack

2011-01-01

Recent data from the Moon, including LCROSS data, indicate large quantities of water ice and other volatiles frozen into the soil in the permanently shadowed craters near the poles. If verified and exploited, these volatiles will revolutionize spaceflight as an inexpensive source of propellants and other consumables outside Earth's gravity well. This report discusses a preliminary investigation of a method to insert a sensor through such a soiVice mixture to verify the presence, nature, and concentration of the ice. It uses percussion to deliver mechanical energy into the frozen mixture, breaking up the ice and decompacting the soil so that only low reaction forces are required from a rover or spacecraft to push the sensor downward. The tests demonstrate that this method may be ideal for a small platform in lunar gravity. However, there are some cases where the system may not be able to penetrate the icy soil, and there is some risk ofthe sensor becoming stuck so that it cannot be retracted, so further work is needed. A companion project (ISDS for Water Detection on the Lunar Surface) has performed preliminary investigation of a dielectric/thermal sensor for use with this system.

Ganymede: A Window into the Evolution of the Jupiter System (Invited)

NASA Astrophysics Data System (ADS)

Collins, G. C.

2009-12-01

Ganymede is unique in that it is the largest satellite in the solar system, the most centrally condensed solid body in the solar system, and the only solid body in the outer solar system known to posses an internally generated magnetic field. At the same time, its surface displays an array of geologic features spanning a wide range of ages and heat flow regimes, which serve as a reference point for understanding features on many other icy satellites. Ganymede’s geological history records evidence of the internal evolution of a large icy satellite, dynamical interactions with the other Galilean satellites, and the evolution of the population of small bodies impacting the surfaces of the satellites. Understanding Ganymede’s structure and history is an important key to understanding the Jupiter system, and large satellite systems around giant planets in general. Summarized here are some of the important questions we currently have about Ganymede: 1) Ganymede is highly differentiated, while its close sibling Callisto is not. What triggered differentiation? Did Ganymede differentiate near the time of accretion, or later in solar system history? 2) Modeling of Ganymede’s gravity field indicates there may be several near-surface mass anomalies. What causes gravity anomalies on icy satellites? What is the link with topography? 3) Two thirds of Ganymede’s surface is covered by bright grooved terrain, recording an episode of intense geological activity. Since the formation of grooved terrain, it appears that heat flow has decreased over time. Did Ganymede experience a pulse of tidal heating that triggered grooved terrain formation? Is it related to interior differentiation? Is it a record of Ganymede’s capture into the Laplace resonance with Europa and Io? 4) Ganymede’s internally generated magnetic field is enclosed within Jupiter’s strong magnetic field, creating a unique environment in our solar system for studying magnetic reconnection and other interaction

Jupiter Eruptions

NASA Image and Video Library

2008-01-25

NASA Hubble Space Telescope shows detailed analysis of two continent-sized storms that erupted in Jupiter atmosphere in March 2007 shows that Jupiter internal heat plays a significant role in generating atmospheric disturbances .

The Radio & Plasma Wave Investigation (RPWI) for JUICE - Instrument Concept and Capabilities

NASA Astrophysics Data System (ADS)

Bergman, J. E. S.

2013-09-01

We present the concept and capabilities of the Radio & Plasma Waves Investigation (RPWI) instrument for the JUICE mission. The RPWI instrument provides measurements of plasma, electric- and magnetic field fluctuations from near DC up to 45 MHz. The RPWI sensors are four Langmuir probes for low temperature plasma diagnostics and electric field measurements, a three-axis searchcoil magnetometer for low-frequency magnetic field measurements, and a three-axial radio antenna, which operates from 80 kHz up to 45 MHz and thus gives RPWI remote sensing capabilities.. In addition, active mutual impedance measurements are used to diagnose the in situ plasma. The RPWI instrument is unique as it provides vector field measurements in the whole frequency range. This makes it possible to employ advanced diagnostics techniques, which are unavailable for scalar measurements. The RPWI instrument has thus outstanding new capabilities not previously available to outer planet missions, which and enables RPWI to address many fundamental planetary science objectives, such as the electrodynamic influence of the Jovian magnetosphere on the exospheres, surfaces and conducting oceans of Ganymede, Europa, and Callisto. RPWI will also be able to investigate the sources of radio emissions from auroral regions of Ganymede and Jupiter, in detail and with unprecedented sensitivity, and possibly also lightning. Moreover, RPWI can search for exhaust plumes from cracks on the icy moons, as well as μm-sized dust and related dust-plasmasurface interaction processes occurring near the icy moons of Jupiter. The top-level blockdiagram of the RPWI instrument is shown here. A detailed technical description of the RPWI instrument will be given.

False Color Mosaic of Jupiter's Belt-Zone Boundary

NASA Technical Reports Server (NTRS)

1997-01-01

This false color mosaic shows a belt-zone boundary near Jupiter's equator. The images that make up the four quadrants of this mosaic were taken within a few minutes of each other. Light at each of Galileo's three near-infrared wavelengths is displayed here in the visible colors red, green and blue. Light at 886 nanometers, strongly absorbed by atmospheric methane and scattered from clouds high in the atmosphere, is shown in red. Light at 732 nanometers, moderately absorbed by atmospheric methane, is shown in green. Light at 757 nanometers, scattered mostly from Jupiter's lower visible cloud deck, is shown in blue. The lower cloud deck appears bluish white, while the higher layer appears pinkish. The holes in the upper layer and their relationships to features in the lower cloud deck can be studied in the lower half of the mosaic. Galileo is the first spacecraft to image different layers in Jupiter's atmosphere.

The edge of the planet runs along the right side of the mosaic. North is at the top. The mosaic covers latitudes -13 to +3 degrees and is centered at longitude 280 degrees west. The smallest resolved features are tens of kilometers in size. These images were taken on Nov. 5, 1996, at a range of 1.2 million kilometers by the solid state imaging (CCD) system aboard NASA's Galileo spacecraft.

Launched in October 1989, Galileo entered orbit around Jupiter on Dec. 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

The Impact of Stars on Moons

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-01-01

In other solar systems, the radiation streaming from the central star can have a destructive impact on the atmospheres of the stars close-in planets. A new study suggests that these exoplanets may also have a much harder time keeping their moons.Where Are the Exomoons?Moons are more common in our solar system than planets by far (just look at Jupiters enormous collection of satellites!) and yet we havent made a single confirmed discovery of a moon around an planet outside of our solar system. Is this just because moons have smaller signals and are more difficult to detect? Or might there also be a physical reason for there to be fewer moons around the planets were observing?Led by Ming Yang, a team of scientists from Nanjing University in China have explored one mechanism that could limit the number of moons we might find around exoplanets: photoevaporation.Artists illustration of the process of photoevaporation, in which the atmosphere of a planet is stripped by radiation from its star. [NASA Goddard SFC]Effects of RadiationPhotoevaporation is a process by which the harsh high-energy radiation from a star blasts a close-in planet, imparting enough energy to the atoms of the planets atmosphere for those atoms to escape. As the planets atmosphere gradually erodes, significant mass loss occurs on timescales of tens or hundreds of millions of years.How might this process affect such a planets moons? To answer this question, Yang and collaborators used an N-body code called MERCURY to model solar systems in which a Neptune-like planet at 0.1 AU gradually loses mass. The planet starts out with a large system of moons, and the team tracks the moons motions to determine their ultimate fates.Escaping BodiesEvolution of the planet mass (top) in a simulation containing 500 small moons. The evolution of the semimajor axes of the moons (middle) and their eccentricities (bottom) are shown, with three example moons, starting at different radii, highlighted in blue, red and green

Ocean-driven heating of Europa's icy shell at low latitudes

NASA Astrophysics Data System (ADS)

Soderlund, K. M.; Schmidt, B. E.; Wicht, J.; Blankenship, D. D.

2014-01-01

The ice shell of Jupiter's moon Europa is marked by regions of disrupted ice known as chaos terrains that cover up to 40% of the satellite's surface, most commonly occurring within 40° of the equator. Concurrence with salt deposits implies a coupling between the geologically active ice shell and the underlying liquid water ocean at lower latitudes. Europa's ocean dynamics have been assumed to adopt a two-dimensional pattern, which channels the moon's internal heat to higher latitudes. Here we present a numerical model of thermal convection in a thin, rotating spherical shell where small-scale convection instead adopts a three-dimensional structure and is more vigorous at lower latitudes. Global-scale currents are organized into three zonal jets and two equatorial Hadley-like circulation cells. We find that these convective motions transmit Europa's internal heat towards the surface most effectively in equatorial regions, where they can directly influence the thermo-compositional state and structure of the ice shell. We suggest that such heterogeneous heating promotes the formation of chaos features through increased melting of the ice shell and subsequent deposition of marine ice at low latitudes. We conclude that Europa's ocean dynamics can modulate the exchange of heat and materials between the surface and interior and explain the observed distribution of chaos terrains.

Studying the Surfaces of the Icy Galilean Satellites With JIMO

NASA Astrophysics Data System (ADS)

Prockter, L.; Schenk, P.; Pappalardo, R.

2003-12-01

The Geology subgroup of the Jupiter Icy Moons Orbiter (JIMO) Science Definition Team (SDT) has been working with colleagues within the planetary science community to determine the key outstanding science goals that could be met by the JIMO mission. Geological studies of the Galilean satellites will benefit from the spacecraft's long orbital periods around each satellite, lasting from one to several months. This mission plan allows us to select the optimal viewing conditions to complete global compositional and morphologic mapping at high resolution, and to target geologic features of key scientific interest at very high resolution. Community input to this planning process suggests two major science objectives, along with corresponding measurements proposed to meet them. Objective 1: Determine the origins of surface features and their implications for geological history and evolution. This encompasses investigations of magmatism (intrusion, extrusion, and diapirism), tectonism (isostatic compensation, and styles of faulting, flexure and folding), impact cratering (morphology and distribution), and gradation (erosion and deposition) processes (impact gardening, sputtering, mass wasting and frosts). Suggested measurements to meet this goal include (1) two dimensional global topographic mapping sufficient to discriminate features at a spatial scale of 10 m, and with better than or equal to 1 m relative vertical accuracy, (2) nested images of selected target areas at a range of resolutions down to the submeter pixel scale, (3) global (albedo) mapping at better than or equal to 10 m/pixel, and (4) multispectral global mapping in at least 3 colors at better than or equal to 100 m/pixel, with some subsets at better than 30 m/pixel. Objective 2. Identify and characterize potential landing sites for future missions. A primary component to the success of future landed missions is full characterization of potential sites in terms of their relative age, geological interest, and

ICIS Model

EPA Pesticide Factsheets

The Integrated Compliance Information System (ICIS) is a web-based system that provides information for the federal enforcement and compliance (FE&C) and the National Pollutant Discharge Elimination System (NPDES) programs.

Energetic charged particle interactions at icy satellites

NASA Astrophysics Data System (ADS)

Nordheim, T.; Hand, K. P.; Paranicas, C.; Howett, C.; Hendrix, A. R.

2016-12-01

Satellites embedded within planetary magnetospheres are typically exposed to bombardment by charged particles, from thermal plasma to more energetic particles at radiation belt energies. At many planetary satellites, energetic charged particles are typically unimpeded by patchy atmospheres or induced satellite magnetic fields and instead are stopped in the surface itself. Most of these primaries have ranges in porous water ice that are at most centimeters, but some of their secondary photons, emitted during the deceleration process, can reach meter depths [Paranicas et al., 2002, 2004; Johnson et al., 2004]. Examples of radiation-induced surface alteration includes sputtering, radiolysis and grain sintering, processes that are capable of significantly altering the physical properties of surface material. Thus, accurate characterization of energetic charged particle weathering at icy satellites is crucial to a more comprehensive understanding of these bodies. At Saturn's inner mid-size moons remote sensing observations by several instruments onboard the Cassini spacecraft have revealed distinct weathering patterns which have been attributed to energetic electron bombardment of the surface [Howett et al., 2011, 2012, 2014; Schenk et al., 2011; Paranicas et al., 2014]. In the Jovian system, radiolytic production of oxidants has been invoked as a potential source of energy for life which may reside in the sub-surface ocean of its satellite Europa [Johnson et al., 2003; Hand et al., 2007; Vance et al., 2016]. Here we will discuss the near-surface energetic charged particle environment of icy satellites, with particular emphasis on comparative studies between the Saturnian and Jovian systems and interpretation of remote sensing observations by instruments onboard missions such as Cassini and Galileo. In addition, we will discuss implications for surface sampling by future lander missions (e.g. the proposed Europa lander now under study).

Europa Imaging Highlights during GEM

NASA Technical Reports Server (NTRS)

1998-01-01

During the two year Galileo Europa Mission (GEM), NASA's Galileo spacecraft will focus intensively on Jupiter's intriguing moon, Europa. This montage shows samples of some of the features that will be imaged during eight successive orbits. The images in this montage are in order of increasing orbit from the upper left (orbit 11) to the lower right (orbit 19).

DESCRIPTIONS AND APPROXIMATE RESOLUTIONSTriple bands and dark spots

1.6 kilometers/pixelConamara Chaos

1.6 kilometers/pixelMannan'an Crater

1.6 kilometers/ pixelCilix

1.6 kilometers/pixelAgenor Linea and Thrace Macula

2 kilometers/pixelSouth polar terrain

2 kilometers/pixelRhadamanthys Linea

1.6 kilometers/pixelEuropa plume search

7 kilometers/pixel

1. Triple bands and dark spots were the focus of some images from Galileo's eleventh orbit of Jupiter. Triple bands are multiple ridges with dark deposits along the outer margins. Some extend for thousands of kilometers across Europa's icy surface. They are cracks in the ice sheet and indicate the great stresses imposed on Europa by tides raised by Jupiter, as well as Europa's neighboring moons, Ganymede and Io. The dark spots or 'lenticulae' are spots of localized disruption.

2. The Conamara Chaos region reveals icy plates which have broken up, moved, and rafted into new positions. This terrain suggests that liquid water or ductile ice was present near the surface. On Galileo's twelfth orbit of Jupiter, sections of this region with resolutions as high as 10 meters per picture element will be obtained.

3. Mannann'an Crater is a feature newly discovered by Galileo in June 1996. Color and high resolution images (to 40 meters per picture element) from Galileo's fourteenth orbit of Jupiter will offer a close look at the crater and help characterize how impacts affect the icy surface of this moon.

4. Cilix, a large mound about 1.5 kilometers high, is the center of Europa's coordinate system. Its concave top and what may be flow

Jupiter Wave

NASA Image and Video Library

2015-10-13

Scientists spotted a rare wave in Jupiter North Equatorial Belt that had been seen there only once before in this false-color close-up from NASA Hubble Telescope. In Jupiter's North Equatorial Belt, scientists spotted a rare wave that had been seen there only once before. It is similar to a wave that sometimes occurs in Earth's atmosphere when cyclones are forming. This false-color close-up of Jupiter shows cyclones (arrows) and the wave (vertical lines). http://photojournal.jpl.nasa.gov/catalog/PIA19659

Effect of the tiger stripes on the deformation of Saturn's moon Enceladus

NASA Astrophysics Data System (ADS)

Souček, Ondřej; Hron, Jaroslav; Běhounková, Marie; Čadek, Ondřej

2016-07-01

Enceladus is a small icy moon of Saturn with active jets of water emanating from fractures around the south pole, informally called tiger stripes, which might be connected to a subsurface water ocean. The effect of these features on periodic tidal deformation of the moon has so far been neglected because of the difficulties associated with implementation of faults in continuum mechanics models. Here we estimate the maximum possible impact of the tiger stripes on tidal deformation and heat production within Enceladus's ice shell by representing them as narrow zones with negligible frictional and bulk resistance passing vertically through the whole ice shell. Assuming a uniform ice shell thickness of 25 km, consistent with the recent estimate of libration, we demonstrate that the faults can dramatically change the distribution of stress and strain in Enceladus's south polar region, leading to a significant increase of the heat production in this area.

A low energy ion beam facility for mass spectrometer calibration: First results

NASA Astrophysics Data System (ADS)

Meyer, Stefan; Tulej, Marek; Wurz, Peter

2018-01-01

The exploration of habitable environments around the gas giants in the Solar System is of major interest in upcoming planetary missions. Exactly this theme is addressed by the Jupiter Icy Moons Explorer (JUICE) mission of the European Space Agency (ESA), which will characterise Ganymede, Europa, and Callisto as planetary objects and potential habitats. The NIM, Neutral gas and Ion Mass spectrometer, is part of the PEP experiment and will be used to measure the chemical composition of the exospheres of the icy Jovian moons. We designed and developed a calibration facility (SATANS, Supersonic cATion and ANion Source), especially for use with the NIM instrument. In a first step, we established a low energy ion beam for positive ions in the range of 0.01-30 eV. Then we conducted beam velocity calibrations with a velocity uncertainty <5%, which provided exact settings and formulas for the cation beam velocity of different gas mixtures in the range of 1-15 km/s. In addition, first results are obtained by using the NIM prototype for direct ion beam measurements under realistic JUICE mission conditions, i.e., for velocities from 1 up to 7 km/s and even more.

Migration of Icy Bodies to the Terrestrial Planets

NASA Astrophysics Data System (ADS)

Sergei, I. I.; Mather, J. C.; Marov, M. Y.

2006-05-01

In our opinion [1-2], some trans-Neptunian objects (TNOs) and planetesimals in the feeding zone of the giant planets with diameters up to 1000 km could be formed directly by the compression of large rarefied dust condensations, but not by the accretion of smaller solid planetesimals. Migration processes of small bodies from the outer regions of the solar system, including the Edgeworth-Kuiper belt, could be responsible for the delivery of the original matter (mainly volatiles) to the terrestrial planets and thus to give rise to the life origin. As migration of TNOs to Jupiter's orbit was studied by several authors, we integrated the orbital evolution of 30,000 Jupiter-crossing objects under the gravitational influence of planets [3]. A few considered objects got Earth-crossing orbits with aphelion distances Q<4.2 AU and moved in such orbits for more than 1 Myr (up to tens or even hundreds of Myrs). Collisions of cometary objects with the terrestrial planets from the Encke- type orbits with aphelia located inside the orbit of Jupiter are assumed to play a greater role than direct impacts from the Jupiter-crossing orbits. It may be possible that the fraction of 1-km former TNOs among near- Earth objects (NEOs) can exceed several tens of percents or most of former TNOs that had got NEO orbits disintegrated into mini-comets and dust during a smaller part of their dynamical lifetimes if these lifetimes are not small. Our estimates show that the amount of icy planetesimals impacted on the Earth during formation of the giant planets is of the order of mass of water in the Earth oceans if the total mass of these planetesimals was about 100 Earth masses. Mars acquired more water per unit of mass of a planet than Earth. During the following 4 Gyr the effectiveness of transport was much less. We integrated [4-5] the orbital evolution of 12,000 dust particles. Probabilites of collisions of particles started from Jupiter-family comets were maximum at diameter d about 100

The High Power Electric Propulsion (HiPEP) Ion Thruster

NASA Technical Reports Server (NTRS)

Foster, John E.; Haag, Tom; Patterson, Michael; Williams, George J., Jr.; Sovey, James S.; Carpenter, Christian; Kamhawi, Hani; Malone, Shane; Elliot, Fred

2004-01-01

Practical implementation of the proposed Jupiter Icy Moon Orbiter (JIMO) mission, which would require a total delta V of approximately 38 km/s, will require the development of a high power, high specific impulse propulsion system. Initial analyses show that high power gridded ion thrusters could satisfy JIMO mission requirements. A NASA GRC-led team is developing a large area, high specific impulse, nominally 25 kW ion thruster to satisfy both the performance and the lifetime requirements for this proposed mission. The design philosophy and development status as well as a thruster performance assessment are presented.

Development of a mass spectrometer for planetary exosphere exploration: from simulations to a flight like design

NASA Astrophysics Data System (ADS)

Meyer, Stefan; Tulej, Marek; Wurz, Peter

2017-04-01

The exploration of habitable environments around the gas giants in the Solar System is of major interest in upcoming planetary missions. Exactly this theme is addressed by the Jupiter Icy Moons Explorer (JUICE) mission of ESA, which will characterise Ganymede, Europa and Callisto as planetary objects and potential habitats [1], [2]. We developed a prototype of the Neutral gas and Ion Mass spectrometer (NIM) of the Particle Environment Package (PEP) for the JUICE mission intended for composition measurements of neutral gas and thermal plasma [3]. NIM/PEP will be used to measure the chemical composition of the exospheres of the icy Jovian moons. Besides direct ion measurement, the NIM instrument is able to measure the inflowing neutral gas in two different modes: in neutral mode the gas enters directly the ion source (open source) and in thermal mode, the gas gets thermally accommodated to wall temperature by several collisions inside an equilibrium sphere before entering the ion source (closed source). We started the development of NIM with detailed ion-optical simulations and optimisations using SIMION software. Based on the ion-optical design we developed a prototype of NIM with several iterations. We tested the prototype NIM under realistic mission conditions and thereby successfully verified its required functionality. We will present the development process from ion-optical simulation up to NIM prototype test results and the concluded flight like design. Furthermore, we will provide an insight into the working principle of NIM and its performance, based on measurement data. References: 1) ESA, "JUICE assessment study report (Yellow Book)", ESA/SRE(2011)18, 2012. 2) O. Grasset, M.K. Dougherty, A. Coustenis, E.J. Bunce, C. Erd, D. Titov, M. Blanc, A. Coates, P. Drossart, L.N. Fletcher, H. Hussmann, R. Jaumann, N. Krupp, J.-P. Lebreton, O. Prieto-Ballesteros, P. Tortora, F. Tosi, T. Van Hoolst, "JUpiter Icy moons Explorer (JUICE): An ESA mission to orbit Ganymede

The structure of Jupiter’s main ring from New Horizons: A comparison with other ring-moon systems

NASA Astrophysics Data System (ADS)

Chancia, Robert; Hedman, Matthew

2018-04-01

During New Horizon’s Jupiter flyby in 2007, the Long-Range Reconnaissance Imager (LORRI) took several images of the planet’s main ring. The data set contains two extended image-movies of the main ring, along with several brief observations at varying ring azimuths, and a small set of high phase angle images. Thus far, the only published work on the New Horizons Jupiter rings data set found seven bright clumps with sub-km equivalent radii embedded in the main ring (Showalter et al. 2007 Science). In this work, we searched the inner region of the main ring for any structures that might be perturbed at the 3:2 resonances with the rotation of Jupiter’s magnetic field or massive storms. We also examined the structure of the outer main ring in order to assess how it is shaped by the small moons Metis and Adrastea. Some of the features seen in Jupiter’s main ring are similar to those found in other dusty rings around Saturn, Uranus, and Neptune. By comparing these different rings, we can gain a better understanding of how small moons sculpt tenuous rings.

Icy Satellites of Saturn: Impact Cratering and Age Determination

NASA Technical Reports Server (NTRS)

Dones, L.; Chapman, C. R.; McKinnon, William B.; Melosh, H. J.; Kirchoff, M. R.; Neukum, G.; Zahnle, K. J.

2009-01-01

Saturn is the first giant planet to be visited by an orbiting spacecraft that can transmit large amounts of data to Earth. Crater counts on satellites from Phoebe inward to the regular satellites and ring moons are providing unprecedented insights into the origin and time histories of the impacting populations. Many Voyager-era scientists concluded that the satellites had been struck by at least two populations of impactors. In this view, the Population I impactors, which were generally judged to be comets orbiting the Sun, formed most of the larger and older craters, while Population II impactors, interpreted as Saturn-orbiting ejecta from impacts on satellites, produced most of the smaller and younger craters. Voyager data also implied that all of the ring moons, and probably some of the midsized classical moons, had been catastrophically disrupted and reaccreted since they formed. We examine models of the primary impactor populations in the Saturn system. At the present time, ecliptic comets, which likely originate in the Kuiper belt/scattered disk, are predicted to dominate impacts on the regular satellites and ring moons, but the models require extrapolations in size (from the observed Kuiper belt objects to the much smaller bodies that produce the craters) or in distance (from the known active Jupiter family comets to 9.5 AU). Phoebe, Iapetus, and perhaps even moons closer to Saturn have been struck by irregular satellites as well. We describe the Nice model, which provides a plausible mechanism by which the entire Solar System might have experienced an era of heavy bombardment long after the planets formed. We then discuss the three cratering chronologies, including one based upon the Nice model, that have been used to infer surface ages from crater densities on the saturnian satellites. After reviewing scaling relations between the properties of impactors and the craters they produce, we provide model estimates of the present-day rate at which comets impact

Production of O2 on icy satellites by electronic excitation of low-temperature water ice.

PubMed

Sieger, M T; Simpson, W C; Orlando, T M

1998-08-06

The signature of condensed molecular oxygen has been reported in recent optical-reflectance measurements of the jovian moon Ganymede, and a tenuous oxygen atmosphere has been observed on Europa. The surfaces of these moons contain large amounts of water ice, and it is thought that O2 is formed by the sputtering of ice by energetic particles from the jovian magnetosphere. Understanding how O2 might be formed from low-temperature ice is crucial for theoretical and experimental simulations of the surfaces and atmospheres of icy bodies in the Solar System. Here we report laboratory measurements of the threshold energy, cross-section and temperature dependence of O2 production by electronic excitation of ice in vacuum, following electron-beam irradiation. Molecular oxygen is formed by direct excitation and dissociation of a stable precursor molecule, rather than (as has been previously thought) by diffusion and chemical recombination of precursor fragments. The large cross-section for O2 production suggests that electronic excitation plays an important part in the formation of O2 on Ganymede and Europa.

The tails of the satellite auroral footprints at Jupiter

NASA Astrophysics Data System (ADS)

Bonfond, B.; Saur, J.; Grodent, D.; Badman, S. V.; Bisikalo, D.; Shematovich, V.; Gérard, J.-C.; Radioti, A.

2017-08-01

The electromagnetic interaction between Io, Europa, and Ganymede and the rotating plasma that surrounds Jupiter has a signature in the aurora of the planet. This signature, called the satellite footprint, takes the form of a series of spots located slightly downstream of the feet of the field lines passing through the moon under consideration. In the case of Io, these spots are also followed by an extended tail in the downstream direction relative to the plasma flow encountering the moon. A few examples of a tail for the Europa footprint have also been reported in the northern hemisphere. Here we present a simplified Alfvénic model for footprint tails and simulations of vertical brightness profiles for various electron distributions, which favor such a model over quasi-static models. We also report here additional cases of Europa footprint tails, in both hemispheres, even though such detections are rare and difficult. Furthermore, we show that the Ganymede footprint can also be followed by a similar tail. Finally, we present a case of a 320° long Io footprint tail, while other cases in similar configurations do not display such a length.

Tidal reorientation and the fracturing of Jupiter's moon Europa

USGS Publications Warehouse

McEwen, A.S.

1986-01-01

The most striking characteristic of Europa is the network of long linear albedo markings over the surface, suggestive of global-scale tectonic processes. Various explanations for the fractures have been proposed: Freezing and expansion of an early liquid water ocean1, planetary expansion due to dehydration of hydrated silicates2, localization by weak points in the crust generated by impacts3, and a combination of stresses due to planetary volume change and tidal distortions from orbital recession and orbital eccentricity4,5. Calculations by Yoder6 and Greenberg and Weidenschilling7 have shown that Europa may rotate slightly more rapidly than the synchronous rate, with a rotation period (reorientation through 360??) ranging from 20 to >103 yr if a liquid mantle is present, or up to 1010 yr if the satellite is essentially solid7. Helfen-stein and Parmentier8 modelled the stresses due to nonsynchronous rotation, and concluded that this could explain the long fractures in part of the anti-jovian hemisphere. In this note, I present a global map of lineaments with long arc lengths (>20?? or 550 km), and compare the lineament orientations to the tensile stress trajectories due to tidal distortions (changes in the lengths of three principal semiaxes) and to nonsynchronous rotation (longitudinal reorientation of two of the principal semiaxes). An excellent orthogonal fit to the lineaments is achieved by the stresses due to nonsynchronous rotation with the axis radial to Jupiter located 25?? east of its present position. This fit suggests that nonsynchronous rotation occurred at some time in Europa's history. ?? 1986 Nature Publishing Group.

Spin-orbit coupling and tidal dissipation in hot Jupiter systems

NASA Astrophysics Data System (ADS)

Shabaltas, Natalia Igorevna

Hot Jupiters are giant planets located extremely close to their host stars, with orbital periods less than 5 days. Many aspects of hot Jupiter (HJ) formation remain unclear, but several clues, such as the observed misalignment between their orbital axes and their hosts' spin axes, point to a dynamical origin. In the first portion of this work we explore the stellar spin-orbit dynamics of one such dynamical formation channel, the Lidov-Kozai mechanism. We show that the coupling between the stellar spin and the planet orbit can lead to complex, and sometimes chaotic, behavior of the stellar spin vector. Many features of this behavior arise due to a set of resonances between the stellar spin axis precession timescale and the Lidov-Kozai timescale. Under the assumption that the stellar quadrupole does not induce precession in the planet's orbit, given a system with a set of initial parameters, we show that it is possible to predict whether the system can attain high spin-orbit misalignments. In the second portion of this work, we discuss tidal dissipation in giant planets, another aspect that is crucial to dynamical HJ formation theories. We show that tidal dissipation in the cores of giant planets can be significant, and can help reconcile inconsistencies in the tidal dissipation efficiencies inferred from observations of Jupiter's moons and from high-eccentricity HJ migration theories. Finally, we improve upon existing core tidal dissipation theories by presenting semi-analytical formulae for dissipation in a core surrounded by a polytropic n = 1 envelope.

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.

Jupiter - Friend or Foe?

NASA Astrophysics Data System (ADS)

Horner, J.; Jones, B. W.

2008-09-01

It has long been believed that the planet Jupiter has played a beneficial role in the development of life on the Earth, acting as a shield from objects which would otherwise go on to significantly raise the impact flux experienced by our planet. Without Jupiter, the story goes, the Earth would have experienced a far greater number of impacts, making it far less hospitable to burgeoning life. In an on-going series of separate studies[1,2], we have examined the effects of varying the mass of Jupiter on the impact flux that the Earth would experience from Near-Earth Objects sourced from the Asteroid belt, short-period comets sourced from the Edgeworth-Kuiper belt, and long-period comets sourced from the Oort cloud. The results are remarkable - it seems that, far from being a shield, Jupiter actually acts to increase the impact flux experienced by the Earth over that which would be expected without the planet. Still more surprising, in the cases of the asteroids and Edgeworth-Kuiper belt objects, it seems that a Jupiter around 0.2 times the mass of "our Jupiter" would be even more threatening, sending a still greater number of objects our way. In order to simulate such disparate populations, different approaches to population construction were needed. The asteroidal and short-period comet populations each contained 100,000 test particles, moving on orbits typical of their class. The asteroids were initially distributed between 2 and 4 AU, with orbits of varying eccentricity and inclination, with number density varying as a function of semi-major axis. The short-period cometary flux was obtained through simulation of a population based on the subset of known Centaurs and Scattered Disk Objects which are Neptune-crossing, and have perihelia beyond the orbit of Uranus. These objects are the parents of the short-period comets, and were chosen since they are a population beyond the current influence of the planet Jupiter. Since our goal was to study the effect of Jupiter

EPA Facility Registry Service (FRS): ICIS

EPA Pesticide Factsheets

This web feature service contains location and facility identification information from EPA's Facility Registry Service (FRS) for the subset of facilities that link to the Integrated Compliance Information System (ICIS). When complete, ICIS will provide a database that will contain integrated enforcement and compliance information across most of EPA's programs. The vision for ICIS is to replace EPA's independent databases that contain enforcement data with a single repository for that information. Currently, ICIS contains all Federal Administrative and Judicial enforcement actions and a subset of the Permit Compliance System (PCS), which supports the National Pollutant Discharge Elimination System (NPDES). ICIS exchanges non-sensitive enforcement/compliance activities, non-sensitive formal enforcement actions and NPDES information with FRS. This web feature service contains the enforcement/compliance activities and formal enforcement action related facilities; the NPDES facilities are contained in the PCS_NPDES web feature service. FRS identifies and geospatially locates facilities, sites or places subject to environmental regulations or of environmental interest. Using vigorous verification and data management procedures, FRS integrates facility data from EPA's national program systems, other federal agencies, and State and tribal master facility records and provides EPA with a centrally managed, single source of comprehensive and authoritative information on f

Microwave observations of jupiter's synchrotron emission during the galileo flyby of amalthea in 2002.

NASA Astrophysics Data System (ADS)

Klein, M. J.; Bolton, S. J.; Bastian, T. S.; Blanc, M.; Levin, S. M.; McLeod, R. J.; MacLaren, D.; Roller, J. P.; Santos-Costa, D.; Sault, R.

2003-04-01

In November, 2002, the Galileo spacecraft trajectory provided a close flyby of Amalthea, one of Jupiter's inner most moons (˜2.4 RJ). During this pass, Galileo entered into a region rarely explored by spacecraft, the inner radiation belts of Jupiter. We present preliminary results from a campaign of microwave observations of Jovian synchrotron emission over a six month interval centered around the flyby. The observations were made with NASA's Deep Space Network (DSN) antennas at Goldstone, California, and the NRAO Very Large Array. We report preliminary measurements of the flux density of the synchrotron emission and the rotational beaming curves and a compare them with the long term history of Jupiter's microwave emission which varies significantly on timescales of months to years. The new data are also being examined to search for evidence of short-term variations and to compare single aperture beaming curves with the spatially resolved images obtained with the VLA. These radio astronomy data will be combined with in-situ measurements from Galileo (see companion paper by Bolton et al) to improve models of the synchrotron emission from Jupiter's radiation belts. A large percentage of the Goldstone observations were conducted by middle- and high school students from classrooms across the nation. The students and their teachers are participants in the Goldstone-Apple Valley Radio Telescope (GAVRT) science education project, which is a partnership involving NASA, the Jet Propulsion Laboratory and the Lewis Center for Educational Research (LCER) in Apple Valley, CA. Working with the Lewis Center over the Internet, GAVRT students conduct remotely controlled radio astronomy observations using 34-m antennas at Goldstone. The JPL contribution to this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration 2756 Planetary magnetospheres (5443, 5737, 6030) 6218 Jovian

The Edge of Jupiter

NASA Image and Video Library

2017-04-19

This enhanced color Jupiter image, taken by the JunoCam imager on NASA's Juno spacecraft, showcases several interesting features on the apparent edge (limb) of the planet. Prior to Juno's fifth flyby over Jupiter's mysterious cloud tops, members of the public voted on which targets JunoCam should image. This picture captures not only a fascinating variety of textures in Jupiter's atmosphere, it also features three specific points of interest: "String of Pearls," "Between the Pearls," and "An Interesting Band Point." Also visible is what's known as the STB Spectre, a feature in Jupiter's South Temperate Belt where multiple atmospheric conditions appear to collide. JunoCam images of Jupiter sometimes appear to have an odd shape. This is because the Juno spacecraft is so close to Jupiter that it cannot capture the entire illuminated area in one image -- the sides get cut off. Juno acquired this image on March 27, 2017, at 2:12 a.m. PDT (5:12 a.m. EDT), as the spacecraft performed a close flyby of Jupiter. When the image was taken, the spacecraft was about 12,400 miles (20,000 kilometers) from the planet. This enhanced color image was created by citizen scientist Bjorn Jonsson. https://photojournal.jpl.nasa.gov/catalog/PIA21389

a 530-590 GHZ Schottky Heterodyne Receiver for High-Resolution Molecular Spectroscopy with Lille's Fast-Scan Fully Solid-State DDS Spectrometer

NASA Astrophysics Data System (ADS)

Pienkina, A.; Margulès, L.; Motiyenko, R. A.; Wiedner, Martina C.; Maestrini, Alain; Defrance, Fabien

2017-06-01

Laboratory spectroscopy, especially at THz and mm-wave ranges require the advances in instrumentation techniques to provide high resolution of the recorded spectra with precise frequency measurement that facilitates the mathematical treatment. We report the first implementation of a Schottky heterodyne receiver, operating at room temperature and covering the range between 530 and 590 GHz, for molecular laboratory spectroscopy. A 530-590 GHz non-cryogenic Schottky solid-state receiver was designed at LERMA, Observatoire de Paris and fabricated in partnership with LPN- CNRS (Laboratoire de Photonique et de Nanostructures), and was initially developed for ESA Jupiter Icy Moons Explorer (JUICE), intended to observe Jupiter and its icy moon atmospheres. It is based on a sub-harmonic Schottky diode mixer, designed and fabricated at LERMA-LPN, pumped by a Local Oscillator (LO), consisting of a frequency Amplifier/Multiplier chains (AMCs) from RPG (Radiometer Physics GmBh). The performance of the receiver was demonstrated by absorption spectroscopy of CH_3CH_2CN with Lille's fast-scan DDS spectrometer. A series of test measurements showed the receiver's good sensitivity, stability and frequency accuracy comparable to those of 4K QMC bolometers, thus making room-temperature Schottky receiver a competitive alternative to 4K QMC bolometers to laboratory spectroscopy applications. We will present the first results with such a combination of a compact room temperature Schottky heterodyne receiver and a fast-scan DDS spectrometer. J. Treuttel, L. Gatilova, A. Maestrini et al., 2016, IEEE Trans. Terahertz Science and Tech., 6, 148-155. This work was funded by the French ANR under the Contract No. ANR-13-BS05-0008-02 IMOLABS.

The Galilean Satellites

NASA Technical Reports Server (NTRS)

1998-01-01

In this 'family portrait,' the four Galilean Satellites are shown to scale. These four largest moons of Jupiter shown in increasing distance from Jupiter are (left to right) Io, Europa, Ganymede, and Callisto.

These global views show the side of volcanically active Io which always faces away from Jupiter, icy Europa, the Jupiter-facing side of Ganymede, and heavily cratered Callisto. The appearances of these neighboring satellites are amazingly different even though they are relatively close to Jupiter (350,000 kilometers for Io; 1, 800,000 kilometers for Callisto). These images were acquired on several orbits at very low 'phase' angles (the sun, spacecraft, moon angle) so that the sun is illuminating the Jovian moons from completely behind the spacecraft, in the same way a full moon is viewed from Earth. The colors have been enhanced to bring out subtle color variations of surface features. North is to the top of all the images which were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

Io, which is slightly larger than Earth's moon, is the most colorful of the Galilean satellites. Its surface is covered by deposits from actively erupting volcanoes, hundreds of lava flows, and volcanic vents which are visible as small dark spots. Several of these volcanoes are very hot; at least one reached a temperature of 2000 degrees Celsius (3600 degrees Fahrenheit) in the summer of 1997. Prometheus, a volcano located slightly right of center on Io's image, was active during the Voyager flybys in 1979 and is still active as Galileo images were obtained. This global view was obtained in September 1996 when Galileo was 485,000 kilometers from Io; the finest details that can be discerned are about 10 km across. The bright, yellowish and white materials located at equatorial latitudes are believed to be composed of sulfur and sulfur dioxide. The polar caps are darker and covered by a redder material.

Europa has a very different surface from its

Electro-optic and radiation damage performance of the CIS115, an imaging sensor for the JANUS optical camera onboard JUICE

NASA Astrophysics Data System (ADS)

Soman, M. R.; Allanwood, E. A. H.; Holland, A. D.; Stefanov, K.; Pratlong, J.; Leese, M.; Gow, J. P. D.; Smith, D. R.

2016-08-01

The Jupiter Icy Moon Explorer (JUICE) has been officially adopted as the next Large class mission by the European Space Agency, with a launch date of 2022. The science payload includes an optical camera, JANUS, which will perform imaging and mapping observations of Jupiter, its moons and icy rings. A 13 slot filter wheel will be used to provide spectral information in order for the JANUS experiment to study the geology and physical properties of Ganymede, Europa and Io, and to investigate processes and structures in the atmosphere of Jupiter. The sensor selected for JANUS is the back-thinned CIS115, a 3 MPixel CMOS Image Sensor from e2v technologies. The CIS115 has a 4-Transistor pixel design with a pinned photodiode to improve signal to noise performance by reducing dark current and allowing for reset level subtraction. The JUICE mission will consist of an 8 year cruise phase followed by a 3 year science phase in the Jovian system. Models of the radiation environment throughout the JUICE mission predict that the End of Life (EOL) non-ionising damage will be equivalent to 1010 protons cm-2 (10 MeV) and the EOL ionising dose will be 100 krad(Si), once the shielding from the spacecraft and instrument design is taken into account. An extensive radiation campaign is therefore being carried out to qualify and characterise the CIS115 for JANUS, as well as other space and terrestrial applications. Radiation testing to take the CIS115 to twice the ionising dose and displacement damage levels was completed in 2015 and the change in sensor performance has been characterised. Good sensor performance has been observed following irradiation and a summary of the key results from the campaign using gamma irradiation (ionising dose) will be presented here, including its soft X-ray detection capabilities, flat-band voltage shift and readout noise. In 2016, further radiation campaigns on flight-representative CIS115s will be undertaken and their results will be disseminated in

Raman Life Detection Instrument Development for Icy Worlds

NASA Technical Reports Server (NTRS)

Thomson, Seamus; Allen, A'Lester; Gutierrez, Daniel; Quinn, Richard C.; Chen, Bin; Koehne, Jessica E.

2017-01-01

The objective of this project is to develop a compact, high sensitivity Raman sensor for detection of life signatures in a flow cell configuration to enable bio-exploration and life detection during future mission to our Solar Systems Icy Worlds. The specific project objectives are the following: 1) Develop a Raman spectroscopy liquid analysis sensor for biosignatures; 2) Demonstrate applicability towards a future Enceladus or other Icy Worlds missions; 3) Establish key parameters for integration with the ARC Sample Processor for Life on Icy Worlds (SPLIce); 4) Position ARC for a successful response to upcoming Enceladus or other Icy World mission instrument opportunities.

Jupiter's Northern Lights

NASA Image and Video Library

2017-09-06

This is a reconstructed view of Jupiter's northern lights through the filters of Juno's Ultraviolet Imaging Spectrometer (UVS) instrument on Dec. 11, 2016, as the Juno spacecraft approached Jupiter, passed over its poles, and plunged towards the equator. Such measurements present a real challenge for the spacecraft's science instruments: Juno flies over Jupiter's poles at 30 miles (50 kilometers) per second -- more than 100,000 miles per hour -- speeding past auroral forms in a matter of seconds. https://photojournal.jpl.nasa.gov/catalog/PIA21938

Soft X-Ray Emissions from Planets and Moons

NASA Technical Reports Server (NTRS)

Bhardwaj, A.; Gladstone, G. R.; Elsner, R. F.; Waite, J. H., Jr.; Grodent, D.; Cravens, T. E.; Howell, R. R.; Metzger, A. E.; Ostgaard, N.; Maurellis, A.;

Recent Formation of Saturnian Moons: Constraints from Their Cratering Records

NASA Astrophysics Data System (ADS)

Dones, Henry C. Luke; Charnoz, Sebastien; Robbins, Stuart J.; Bierhaus, Edward B.

2015-05-01

Charnoz et al. (2010) proposed that Saturn's small "ring moons" out to Janus and Epimetheus consist of ring material that viscously spread beyond the Roche limit and coagulated into moonlets. The moonlets evolve outward due to the torques they exert at resonances in the rings. More massive moonlets migrate faster; orbits can cross and bodies can merge, resulting in a steep trend of mass vs. distance from the planet. Canup (2010) theorized that Saturn's rings are primordial and originated when a differentiated, Titan-like moon migrated inward when the planet was still surrounded by a gas disk. The satellite's icy shell could have been tidally stripped, and would have given rise to today's rings and the mid-sized moons out to Tethys. Charnoz et al. (2011) investigated the formation of satellites out to Rhea from a spreading massive ring, and Crida and Charnoz (2012) extended this scenario to other planets. Once the mid-sized moons recede far from the rings, tidal interaction with the planet determines the rate at which the satellites migrate. Charnoz et al. (2011) found that Mimas would have formed about 1 billion years more recently than Rhea. The cratering records of these moons (Kirchoff and Schenk 2010; Robbins et al. 2015) provide a test of this scenario. If the mid-sized moons are primordial, most of their craters were created through hypervelocity impacts by ecliptic comets from the Kuiper Belt/Scattered Disk (Zahnle et al. 2003; Dones et al. 2009). In the Charnoz et al. scenario, the oldest craters on the moons would result from low-speed accretionary impacts. We thank the Cassini Data Analysis program for support.ReferencesCanup, R. M. (2010). Nature 468, 943Charnoz, S.; Salmon, J., Crida, A. (2010). Nature 465, 752Charnoz, S., et al. (2011). Icarus 216, 535Crida, A.; Charnoz, S. (2012). Science 338, 1196Dones, L., et al. (2009). In Saturn from Cassini-Huygens, p. 613Kirchoff, M. R.; Schenk, P. (2010). Icarus 206, 485Robbins, S. J.; Bierhaus, E. B.; Dones, L

PCS-ICIS Model

EPA Pesticide Factsheets

The Integrated Compliance Information System (ICIS) is a web-based system that provides information for the federal enforcement and compliance (FE&C) and the National Pollutant Discharge Elimination System (NPDES) programs.

Jupiter's first 100 miles

PubMed

Reichhardt, T

1996-04-01

In December, 1995, after a journey of six years, the Galileo probe plunged into Jupiter's atmosphere, becoming the first artificial object to make direct contact with an outer planet. New data supplied by the probe indicated: 1) A new radiation belt around Jupiter ten times stronger than the Van Allen belt around Earth; 2) Jupiter may be much drier than predicted. Its atmosphere contains about as much water as the Sun, but this is subject to instrument calibration uncertainties, and the location of the landing in one of the driest spots on the planet; 3) Jupiter's atmosphere appears to have about three to ten times less lightning than Earth's, while the events are about 10 times stronger, both in terms of size and amount of electrical discharge; and, 4) Jupiter's winds were stronger than expected, increasing with depth, at 330 mph.

Voyager 2 Jupiter encounter

NASA Technical Reports Server (NTRS)

1979-01-01

A NASA News Release is presented which contains the following: (1) general release; (2) two views of Voyager 2 flight past Jupiter; (3) Voyager mission summary; (4) Voyager 1 science results; (5) Jupiter science objectives; (6) Jupiter the planet and its satellites; (7) Voyager experiments; (8) planet comparison; (9) a list of Voyager science investigators and (10) the Voyager team.

The Other Chemistry of the Jovian Icy Satellites - Low Energy and Sulfurous

NASA Technical Reports Server (NTRS)

Hudson, Reggie L.; Loeffler, M. J.; Moore, M. H.

2010-01-01

Spectra of Jupiter's icy satellites reveal surfaces dominated by H2O-ice with minor amounts of SO2 and other materials. The co-existence of H2O and SO2 in surfaces exposed to jovian magnetospheric radiation suggests that sulfuric acid (H2SO4) also could be present. This was noted by Carlson et al. (1999), who supported this suggestion with assignments of near-IR bands in Europa spectra to hydrated H2SO4. Laboratory experiments since have demonstrated radiolytically-driven syntheses in S- and SO2-containing H2O-Ices (Carlson et al., 2002; Moore et al., 2006). In the Cosmic Ice Laboratory, we recently have investigated the thermal chemistry of SO2 trapped in H2O-ice. IR spectra of H2O + SO2 mixtures recorded at 10 to 230 K were used to follow low-temperature reactions in the absence of radiation effects. No SO2 reactions were found at 10 K, but warming to more-relevant Europa temperatures produced both HSO3(-) and S2O5(2-). Added NH3 shifted the product composition toward SO3(2-) and away from the other ions. We find that H2O and SO2 react to produce sulfur oxyanions, such as bisulfite, that as much as 30% of the SO2 can be consumed through this reaction, and that the products remain in the ice when the temperature is lowered, indicating that these reactions are irreversible. Our results suggest that thermally-induced reactions can alter the chemistry at and below the surfaces of the icy satellites in the jovian system.

Moon - 18 Image Mosaic

NASA Technical Reports Server (NTRS)

1992-01-01

This mosaic picture of the Moon was compiled from 18 images taken with a green filter by Galileo's imaging system during the spacecraft's flyby on December 7, 1992, some 11 hours before its Earth flyby at 1509 UTC (7:09 a.m. Pacific Standard Time) December 8. The north polar region is near the top part of the mosaic, which also shows Mare Imbrium, the dark area on the left; Mare Serenitatis at center; and Mare Crisium, the circular dark area to the right. Bright crater rim and ray deposits are from Copernicus, an impact crater 96 kilometers (60 miles) in diameter. Computer processing has exaggerated the brightness of poorly illuminated features near the day/night terminator in the polar regions, giving a false impression of high reflectivity there. The digital image processing was done by DLR the German aerospace research establishment near Munich, an international collaborator in the Galileo mission. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory.

Featured Image: Active Cryovolcanism on Europa?

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-05-01

Nighttime thermal image from the Galileo Photopolarimeter-Radiometer, revealing a thermal anomaly around the region where the plumes were observed. [Sparks et al. 2017]This image shows a 1320 900 km, high-resolution Galileo/Voyager USGS map of the surface of Europa, one of Jupiters moons. In March 2014, observations of Europa revealed a plume on its icy surface coming from somewhere within the green ellipse. In February 2016, another plume was observed, this time originating from somewhere within the cyan ellipse. In addition, a nighttime thermal image from the Galileo Photopolarimeter-Radiometer has revealed a thermal anomaly a region of unusually high temperature near the same location. In a recent study led by William Sparks (Space Telescope Science Institute), a team of scientists presents these observations and argues that they provide mounting evidence of active water-vapor venting from ongoing cryovolcanism beneath Europas icy surface. If this is true, then Europas surface is active and provides access to the liquid water at depth boosting the case for Europas potential habitability and certainly making for an interesting target point for future spacecraft exploration of this moon. For more information, check out the paper below!CitationW. B. Sparks et al 2017 ApJL 839 L18. doi:10.3847/2041-8213/aa67f8

Assessing the potential for passive radio sounding of Europa and Ganymede with RIME and REASON

NASA Astrophysics Data System (ADS)

Schroeder, Dustin M.; Romero-Wolf, Andrew; Carrer, Leonardo; Grima, Cyril; Campbell, Bruce A.; Kofman, Wlodek; Bruzzone, Lorenzo; Blankenship, Donald D.

2016-12-01

Recent work has raised the potential for Jupiter's decametric radiation to be used as a source for passive radio sounding of its icy moons. Two radar sounding instruments, the Radar for Icy Moon Exploration (RIME) and the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) have been selected for ESA and NASA missions to Ganymede and Europa. Here, we revisit the projected performance of the passive sounding concept and assess the potential for its implementation as an additional mode for RIME and REASON. We find that the Signal to Noise Ratio (SNR) of passive sounding can approach or exceed that of active sounding in a noisy sub-Jovian environment, but that active sounding achieves a greater SNR in the presence of quiescent noise and outperforms passive sounding in terms of clutter. We also compare the performance of passive sounding at the 9 MHz HF center frequency of RIME and REASON to other frequencies within the Jovian decametric band. We conclude that the addition of a passive sounding mode on RIME or REASON stands to enhance their science return by enabling sub-Jovian HF sounding in the presence of decametric noise, but that there is not a compelling case for implementation at a different frequency.

Ion Acceleration at Earth, Saturn and Jupiter and its Global Impact on Magnetospheric Structure

NASA Astrophysics Data System (ADS)

Brandt, Pontus

2016-07-01

-midnight sector that seem to be related to centrifugal interchange. We will show how the plasma pressure resulting from the large-scale injections perturb the magnetic field and give rise the periodic oscillations as measured by Cassini. At Jupiter, quasi-periodic, large-scale injections also occur in the post-midnight sector, but at much larger distances. Analysis of Galileo measurements have shown that there are also features with similarities to the effects of planetward moving dipolarization fronts, and that the protons, O+ and S+ have different spectral signatures. Although the magnetodisc structure is partly a result of centrifugal forces exerted by the cold plasma, the anisotropies of the hot plasma have been found to account for a very significant part of the force-balance responsible for the disc structure. We will briefly also discuss our science planning and development of the plasma, energetic particle and ENA instrumentation on board the ESA Jupiter Icy moon Explorer and how we plan to address these intriguing science topics.

The Global Contribution of Secondary Craters on the Icy Satellites

NASA Astrophysics Data System (ADS)

Hoogenboom, T.; Johnson, K. E.; Schenk, P.

2014-12-01

At present, surface ages of bodies in the Outer Solar System are determined only from crater size-frequency distributions (a method dependent on an understanding of the projectile populations responsible for impact craters in these planetary systems). To derive accurate ages using impact craters, the impactor population must be understood. Impact craters in the Outer Solar System can be primary, secondary or sesquinary. The contribution of secondary craters to the overall population has recently become a "topic of interest." Our objective is to better understand the contribution of dispersed secondary craters to the small crater populations, and ultimately that of small comets to the projectile flux on icy satellites in general. We measure the diameters of obvious secondary craters (determined by e.g. irregular crater shape, small size, clustering) formed by all primary craters on Ganymede for which we have sufficiently high resolution data to map secondary craters. Primary craters mapped range from approximately 40 km to 210 km. Image resolution ranges from 45 to 440 m/pixel. Bright terrain on Ganymede is our primary focus. These resurfaced terrains have relatively low crater densities and serve as a basis for characterizing secondary populations as a function of primary size on an icy body for the first time. Although focusing on Ganymede, we also investigate secondary crater size, frequency, distribution, and formation, as well as secondary crater chain formation on icy satellites throughout the Saturnian and Jovian systems principally Rhea. We compare our results to similar studies of secondary cratering on the Moon and Mercury. Using Galileo and Voyager data, we have identified approximately 3,400 secondary craters on Ganymede. In some cases, we measured crater density as a function of distance from a primary crater. Because of the limitations of the Galileo data, it is necessary to extrapolate from small data sets to the global population of secondary craters

Jupiter Environment Tool

NASA Technical Reports Server (NTRS)

Sturm, Erick J.; Monahue, Kenneth M.; Biehl, James P.; Kokorowski, Michael; Ngalande, Cedrick,; Boedeker, Jordan

2012-01-01

The Jupiter Environment Tool (JET) is a custom UI plug-in for STK that provides an interface to Jupiter environment models for visualization and analysis. Users can visualize the different magnetic field models of Jupiter through various rendering methods, which are fully integrated within STK s 3D Window. This allows users to take snapshots and make animations of their scenarios with magnetic field visualizations. Analytical data can be accessed in the form of custom vectors. Given these custom vectors, users have access to magnetic field data in custom reports, graphs, access constraints, coverage analysis, and anywhere else vectors are used within STK.

Saturn's icy satellites investigated by Cassini-VIMS. II. Results at the end of nominal mission

USGS Publications Warehouse

Filacchione, G.; Capaccioni, F.; Clark, R.N.; Cuzzi, J.N.; Cruikshank, D.P.; Coradini, A.; Cerroni, P.; Nicholson, P.D.; McCord, T.B.; Brown, R.H.; Buratti, B.J.; Tosi, F.; Nelson, R.M.; Jaumann, R.; Stephan, K.

2010-01-01

We report the detailed analysis of the spectrophotometric properties of Saturn's icy satellites as derived by full-disk observations obtained by visual and infrared mapping spectrometer (VIMS) experiment aboard Cassini. In this paper, we have extended the coverage until the end of the Cassini's nominal mission (June 1st 2008), while a previous paper (Filacchione, G., and 28 colleagues [2007]. Icarus 186, 259-290, hereby referred to as Paper I) reported the preliminary results of this study. During the four years of nominal mission, VIMS has observed the entire population of Saturn's icy satellites allowing us to make a comparative analysis of the VIS-NIR spectral properties of the major satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Hyperion, Iapetus) and irregular moons (Atlas, Prometheus, Pandora, Janus, Epimetheus, Telesto, Calypso, Phoebe). The results we discuss here are derived from the entire dataset available at June 2008 which consists of 1417 full-disk observations acquired from a variety of distances and inclinations from the equatorial plane, with different phase angles and hemispheric coverage. The most important spectrophotometric indicators (as defined in Paper I: I/F continua at 0.55 ??m, 1.822 ??m and 3.547 ??m, visible spectral slopes, water and carbon dioxide bands depths and positions) are calculated for each observation in order to investigate the disk-integrated composition of the satellites, the distribution of water ice respect to "contaminants" abundances and typical regolith grain properties. These quantities vary from the almost pure water ice surfaces of Enceladus and Calypso to the organic and carbon dioxide rich Hyperion, Iapetus and Phoebe. Janus visible colors are intermediate between these two classes having a slightly positive spectral slope. These results could help to decipher the origins and evolutionary history of the minor moons of the Saturn's system. We introduce a polar representation of the spectrophotometric

Voyage to Jupiter.

ERIC Educational Resources Information Center

Morrison, David; Samz, Jane

This publication illustrates the features of Jupiter and its family of satellites pictured by the Pioneer and the Voyager missions. Chapters included are: (1) "The Jovian System" (describing the history of astronomy); (2) "Pioneers to Jupiter" (outlining the Pioneer Mission); (3) "The Voyager Mission"; (4)…

Jupiter: friend or foe?

NASA Astrophysics Data System (ADS)

Horner, Jonti; Jones, Barrie W.

2008-02-01

The idea that Jupiter has shielded the Earth from potentially catastrophic impacts has long permeated the public and scientific mind. But has it shielded us? We are carrying out the first detailed examination of the degree of shielding provided by Jupiter and have obtained some surprising results. Rather than Jupiter acting as a defensive presence, we found that it actually makes little difference - but if Jupiter were significantly smaller, the impact rate experienced by the Earth would be considerably enhanced. Indeed, it seems that a giant planet in the outer reaches of a planetary system can actually pose a threat to the habitability of terrestrial worlds closer to the system's parent star.

Jupiter with Io Crossing

NASA Image and Video Library

1996-09-26

million kilometers). The satellite's shadow can be seen falling on the face of Jupiter at left. Io is traveling from left to right in its one-and-three-quarter-day orbit around Jupiter. Even from this great distance the image of Io shows dark poles and a bright equatorial region. Voyager will make its closest approach to Jupiter -- 174,000 miles (280,000 kilometer) -- on March 5. It will then continue to Saturn in November 1980, Meanwhile Voyager 2, a sister spacecraft, will fly past Jupiter July 9, 1979, and reach Saturn in August 1981. This color image was taken through orange, green and blue filters. http://photojournal.jpl.nasa.gov/catalog/PIA00455

A New Look at Jupiter: Results at the Now Frontier. [Pioneer 10, interplanetary space, and Jupiter atmosphere

NASA Technical Reports Server (NTRS)

1975-01-01

Pioneer 10's encounter with Jupiter is discussed along with the interplanetary space beyond the orbit of Mars. Other topics discussed include the size of Jupiter, the Galilean satellites, the magnetic field of Jupiter, radiation belts, Jupiter's weather and interior, and future exploration possibilities. Educational projects are also included.

Evidence of a plume on Europa from Galileo magnetic and plasma wave signatures

NASA Astrophysics Data System (ADS)

Jia, Xianzhe; Kivelson, Margaret G.; Khurana, Krishan K.; Kurth, William S.

2018-05-01

The icy surface of Jupiter's moon, Europa, is thought to lie on top of a global ocean1-4. Signatures in some Hubble Space Telescope images have been associated with putative water plumes rising above Europa's surface5,6, providing support for the ocean theory. However, all telescopic detections reported were made at the limit of sensitivity of the data5-7, thereby calling for a search for plume signatures in in-situ measurements. Here, we report in-situ evidence of a plume on Europa from the magnetic field and plasma wave observations acquired on Galileo's closest encounter with the moon. During this flyby, which dropped below 400 km altitude, the magnetometer8 recorded an approximately 1,000-kilometre-scale field rotation and a decrease of over 200 nT in field magnitude, and the Plasma Wave Spectrometer9 registered intense localized wave emissions indicative of a brief but substantial increase in plasma density. We show that the location, duration and variations of the magnetic field and plasma wave measurements are consistent with the interaction of Jupiter's corotating plasma with Europa if a plume with characteristics inferred from Hubble images were erupting from the region of Europa's thermal anomalies. These results provide strong independent evidence of the presence of plumes at Europa.

Evidence of a plume on Europa from Galileo magnetic and plasma wave signatures

NASA Astrophysics Data System (ADS)

Jia, Xianzhe; Kivelson, Margaret G.; Khurana, Krishan K.; Kurth, William S.

2018-06-01

The icy surface of Jupiter's moon, Europa, is thought to lie on top of a global ocean1-4. Signatures in some Hubble Space Telescope images have been associated with putative water plumes rising above Europa's surface5,6, providing support for the ocean theory. However, all telescopic detections reported were made at the limit of sensitivity of the data5-7, thereby calling for a search for plume signatures in in-situ measurements. Here, we report in-situ evidence of a plume on Europa from the magnetic field and plasma wave observations acquired on Galileo's closest encounter with the moon. During this flyby, which dropped below 400 km altitude, the magnetometer8 recorded an approximately 1,000-kilometre-scale field rotation and a decrease of over 200 nT in field magnitude, and the Plasma Wave Spectrometer9 registered intense localized wave emissions indicative of a brief but substantial increase in plasma density. We show that the location, duration and variations of the magnetic field and plasma wave measurements are consistent with the interaction of Jupiter's corotating plasma with Europa if a plume with characteristics inferred from Hubble images were erupting from the region of Europa's thermal anomalies. These results provide strong independent evidence of the presence of plumes at Europa.

Autonomous Control Capabilities for Space Reactor Power Systems

NASA Astrophysics Data System (ADS)

Wood, Richard T.; Neal, John S.; Brittain, C. Ray; Mullens, James A.

2004-02-01

The National Aeronautics and Space Administration's (NASA's) Project Prometheus, the Nuclear Systems Program, is investigating a possible Jupiter Icy Moons Orbiter (JIMO) mission, which would conduct in-depth studies of three of the moons of Jupiter by using a space reactor power system (SRPS) to provide energy for propulsion and spacecraft power for more than a decade. Terrestrial nuclear power plants rely upon varying degrees of direct human control and interaction for operations and maintenance over a forty to sixty year lifetime. In contrast, an SRPS is intended to provide continuous, remote, unattended operation for up to fifteen years with no maintenance. Uncertainties, rare events, degradation, and communications delays with Earth are challenges that SRPS control must accommodate. Autonomous control is needed to address these challenges and optimize the reactor control design. In this paper, we describe an autonomous control concept for generic SRPS designs. The formulation of an autonomous control concept, which includes identification of high-level functional requirements and generation of a research and development plan for enabling technologies, is among the technical activities that are being conducted under the U.S. Department of Energy's Space Reactor Technology Program in support of the NASA's Project Prometheus. The findings from this program are intended to contribute to the successful realization of the JIMO mission.

Ultra High Voltage Propellant Isolators and Insulators for JIMO Ion Thrusters

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Gaier, James R.; Hung, Ching-Cheh; Walters, Patty A.; Sechkar, Ed; Panko, Scott; Kamiotis, Christina A.

2004-01-01

Within NASA's Project Prometheus, high specific impulse ion thrusters for electric propulsion of spacecraft for the proposed Jupiter Icy Moon Orbiter (JIMO) mission to three of Jupiter's moons: Callisto, Ganymede and Europa will require high voltage operation to meet mission propulsion. The anticipated approx.6,500 volt net ion energy will require electrical insulation and propellant isolation which must exceed that used successfully by the NASA Solar Electric Propulsion Technology Readiness (NSTAR) Deep Space 1 mission thruster by a factor of approx.6. Xenon propellant isolator prototypes that operate at near one atmosphere and prototypes that operate at low pressures (<100 Torr) have been designed and are being tested for suitability to the JIMO mission requirements. Propellant isolators must be durable to Paschen breakdown, sputter contamination, high temperature, and high voltage while operating for factors longer duration than for the Deep Space 1 Mission. Insulators used to mount the thrusters as well as those needed to support the ion optics have also been designed and are under evaluation. Isolator and insulator concepts, design issues, design guidelines, fabrication considerations and performance issues are presented. The objective of the investigation was to identify candidate isolators and insulators that are sufficiently robust to perform durably and reliably during the proposed JIMO mission.

Voyager 2 Jupiter Eruption Movie

NASA Technical Reports Server (NTRS)

2000-01-01

This movie records an eruptive event in the southern hemisphere of Jupiter over a period of 8 Jupiter days. Prior to the event, an undistinguished oval cloud mass cruised through the turbulent atmosphere. The eruption occurs over avery short time at the very center of the cloud. The white eruptive material is swirled about by the internal wind patterns of the cloud. As a result of the eruption, the cloud then becomes a type of feature seen elsewhere on Jupiter known as 'spaghetti bowls'.

As Voyager 2 approached Jupiter in 1979, it took images of the planet at regular intervals. This sequence is made from 8 images taken once every Jupiter rotation period (about 10 hours). These images were acquired in the Violet filter around May 6, 1979. The spacecraft was about 50 million kilometers from Jupiter at that time.

This time-lapse movie was produced at JPL by the Image Processing Laboratory in 1979.

Core Analysis Combining MT (TIPPER) and Dielectric Sensors (Sans EC) in Earth and Space

NASA Technical Reports Server (NTRS)

Mound, Michael C.; Dudley, Kenneth L.

2015-01-01

nuclear powered heated tip for melting through the ice sheath of Europa and inserting a down hole SansEC with TIPPER interface. NASA's Juno space probe already on the way to Jupiter as part of the Exploration New Frontiers Program and the planned Europa mission will conduct detailed reconnaissance of Jupiter's moon Europa and investigate whether the icy moon could harbor conditions suitable for life. It has already been observed that Jovian moons have auroras that may serve as naturally occurring active energy sources for a TIPPER instrument.

Biogeochemical fingerprints of life: earlier analogies with polar ecosystems suggest feasible instrumentation for probing the Galilean moons

NASA Astrophysics Data System (ADS)

Chela-Flores, J.; Cicuttin, A.; Crespo, M. L.; Tuniz, C.

2015-07-01

We base our search for the right instrumentation for detecting biosignatures on Europa on the analogy suggested by the recent work on polar ecosystems in the Canadian Arctic at Ellesmere Island. In that location sulphur patches (analogous to the Europan patches) are accumulating on glacial ice lying over saline springs rich in sulphate and sulphide. Their work reinforces earlier analogies in Antarctic ecosystems that are appropriate models for possible habitats that will be explored by the European Space Agency JUpiter ICy Moons Explorer (JUICE) mission to the Jovian System. Its Jupiter Ganymede Orbiter (JGO) will include orbits around Europa and Ganymede. The Galileo orbital mission discovered surficial patches of non-ice elements on Europa that were widespread and, in some cases possibly endogenous. This suggests the possibility that the observed chemical elements in the exoatmosphere may be from the subsurface ocean. Spatial resolution calculations of Cassidy and co-workers are available, suggesting that the atmospheric S content can be mapped by a neutral mass spectrometer, now included among the selected JUICE instruments. In some cases, large S-fractionations are due to microbial reduction and disproportionation (although sometimes providing a test for ecosystem fingerprints, even though with Sim - Bosak - Ono we maintain that microbial sulphate reduction large sulphur isotope fractionation does not require disproportionation. We address the question of the possible role of oxygen in the Europan ocean. Instrument issues are discussed for measuring stable S-isotope fractionations up to the known limits in natural populations of δ34 ~ -70‰. We state the hypothesis of a Europa anaerobic oceanic population of sulphate reducers and disproportionators that would have the effect of fractionating the sulphate that reaches the low-albedo surficial regions. This hypothesis is compatible with the time-honoured expectation of Kaplan and co-workers (going back to the

Icy Particle Spray

NASA Image and Video Library

2010-11-18

Images obtained by NASA EPOXI mission spacecraft show an active end of the nucleus of comet Hartley 2. Icy particles spew from the surface. Most of these particles are traveling with the nucleus; fluffy nowballs about 3 centimeters to 30 centimeters.

Full Jupiter Mosaic

NASA Technical Reports Server (NTRS)

2007-01-01

This image of Jupiter is produced from a 2x2 mosaic of photos taken by the New Horizons Long Range Reconnaissance Imager (LORRI), and assembled by the LORRI team at the Johns Hopkins University Applied Physics Laboratory. The telescopic camera snapped the images during a 3-minute, 35-second span on February 10, when the spacecraft was 29 million kilometers (18 million miles) from Jupiter. At this distance, Jupiter's diameter was 1,015 LORRI pixels -- nearly filling the imager's entire (1,024-by-1,024 pixel) field of view. Features as small as 290 kilometers (180 miles) are visible.

Both the Great Red Spot and Little Red Spot are visible in the image, on the left and lower right, respectively. The apparent 'storm' on the planet's right limb is a section of the south tropical zone that has been detached from the region to its west (or left) by a 'disturbance' that scientists and amateur astronomers are watching closely.

At the time LORRI took these images, New Horizons was 820 million kilometers (510 million miles) from home -- nearly 51/2 times the distance between the Sun and Earth. This is the last full-disk image of Jupiter LORRI will produce, since Jupiter is appearing larger as New Horizons draws closer, and the imager will start to focus on specific areas of the planet for higher-resolution studies.

Ammonia Clouds on Jupiter

NASA Technical Reports Server (NTRS)

2007-01-01

[figure removed for brevity, see original site] Click on the image for movie of Ammonia Ice Clouds on Jupiter

In this movie, put together from false-color images taken by the New Horizons Ralph instrument as the spacecraft flew past Jupiter in early 2007, show ammonia clouds (appearing as bright blue areas) as they form and disperse over five successive Jupiter 'days.' Scientists noted how the larger cloud travels along with a small, local deep hole.

Updated modeling of Io and non-Io Radio Auroral Emissions of Jupiter

NASA Astrophysics Data System (ADS)

Louis, C.; Lamy, L.; Zarka, P.; Cecconi, B.; Hess, S.

2015-10-01

The radio auroral emissions produced by the Jupiter's magnetosphere between a few kHz and 40MHz, the most intense of our Solar System, are known since half a century, but they still drive many questions, and their deepened study is one of the main aim of the JUNO missions (arrival in July 2016). Jovian auroral radio emissions are thought to be produced through the Cyclotron Maser Instability (CMI), from non-maxwellian weakly relativistic electrons gyrating along high-latitude magnetic fields lines (Zarka, 1998). These emissions divide in different spectral components, driven or not by the moon Io. The origin and the relationship between kilometric, hectometric and decametric non-Io emissions in particular remains poorly understood. To investigate these emissions, we simulated numerical dynamic spectra with the most recent version of the ExPRES code - Exoplanetary and Planetary Radio Emission Simulator, available at http://maser.obspm.fr - already used to successfully model Io decametric and Saturn's kilometric arcshaped emissions (Hess et al., 2008, Lamy et al., 2008) and predict exoplanetary radio emissions (Hess et al., 2011). Such simulations bring direct constraints on the locus of active magnetic field lines and on the nature of CMI-unstable electrons (Hess et al., submitted). We validated the new theoretical calculation of the beaming angle used by ExPRES, which now includes refraction at the source. We then built updated simulations of Io and non-Io emissions which were compared to the radio observations acquired by the Cassini spacecraft (Jupiter flyby in 2000) and the Nançay decameter array (routines observations of Jupiter).

Deep ice and salty oceans of icy worlds, how high pressures influence their thermodynamics and provide constrains on extraterrestrial habitability

NASA Astrophysics Data System (ADS)

Journaux, B.; Brown, J. M.; Bollengier, O.; Abramson, E.

2017-12-01

As in Earth arctic and Antarctic regions, suspected extraterrestrial deep oceans in icy worlds (i.e. icy moons and water-rich exoplanets) chemistry and thermodynamic state will strongly depend on their equilibrium with H2O ice and present solutes. Na-Mg-Cl-SO4 salt species are currently the main suspected ionic solutes to be present in deep oceans based on remote sensing, magnetic field measurements, cryovolcanism ice grains chemical analysis and chondritic material aqueous alteration chemical models. Unlike on our planet, deep extraterrestrial ocean might also be interacting at depth with high pressure ices (e.g. III, V, VI, VI, X) which have different behavior compared to ice Ih. Unfortunately, the pressures and temperatures inside these hydrospheres differ significantly from the one found in Earth aqueous environments, so most of our current thermodynamic databases do not cover the range of conditions relevant for modeling realistically large icy worlds interiors. Recent experimental results have shown that the presence of solutes, and more particularly salts, in equilibrium with high pressure ices have large effects on the stability, buoyancy and chemistry of all the phases present at these extreme conditions. High pressure in-situ measurements using diamond anvil cell apparatus were operated both at the University of washington and at the European Synchrotron Radiation Facility on aqueous systems phase diagrams with Na-Mg-Cl-SO4 species, salt incorporation in high pressure ices and density inversions between the solid and the fluids. These results suggest a more complex picture of the interior structure, dynamic and chemical evolution of large icy worlds hydrospheres when solutes are taken into account, compared to current models mainly using pure water. Based on our in-situ experimental measurements, we propose the existence of new liquid environments at greater depths and the possibility of solid state transport of solute through the high pressure ices

On the contribution of PRIDE-JUICE to Jovian system ephemerides

NASA Astrophysics Data System (ADS)

Dirkx, D.; Gurvits, L. I.; Lainey, V.; Lari, G.; Milani, A.; Cimò, G.; Bocanegra-Bahamon, T. M.; Visser, P. N. A. M.

2017-11-01

The Jupiter Icy Moons Explorer (JUICE) mission will perform detailed measurements of the properties of the Galilean moons, with a nominal in-system science-mission duration of about 3.5 years. Using both the radio tracking data, and (Earth- and JUICE-based) optical astrometry, the dynamics of the Galilean moons will be measured to unprecedented accuracy. This will provide crucial input to the determination of the ephemerides and physical properties of the system, most notably the dissipation in Io and Jupiter. The data from Planetary Radio Interferometry and Doppler Experiment (PRIDE) will provide the lateral position of the spacecraft in the International Celestial Reference Frame (ICRF). In this article, we analyze the relative quantitative influence of the JUICE-PRIDE observables to the determination of the ephemerides of the Jovian system and the associated physical parameters. We perform a covariance analysis for a broad range of mission and system characteristics. We analyze the influence of VLBI data quality, observation planning, as well as the influence of JUICE orbit determination quality. This provides key input for the further development of the PRIDE observational planning and ground segment development. Our analysis indicates that the VLBI data are especially important for constraining the dynamics of Ganymede and Callisto perpendicular to their orbital planes. Also, the use of the VLBI data makes the uncertainty in the ephemerides less dependent on the error in the orbit determination of the JUICE spacecraft itself. Furthermore, we find that optical astrometry data of especially Io using the JANUS instrument will be crucial for stabilizing the solution of the normal equations. Knowledge of the dissipation in the Jupiter system cannot be improved using satellite dynamics obtained from JUICE data alone, the uncertainty in Io's dissipation obtained from our simulations is similar to the present level of uncertainty.

The display of sexual behaviors by female rats administered ICI 182,780.

PubMed

Clark, Ann S; Guarraci, Fay A; Megroz, Alison B; Porter, Donna M; Henderson, Leslie P

2003-04-01

ICI 182,780 (ICI) is a pure antiestrogen that when administered systemically does not cross the blood-brain barrier, thus its actions are limited to the periphery. Four experiments were conducted to test the effects of ICI on the display of sexual behaviors in ovariectomized rats. Experiment 1 examined the effects of three doses of ICI (250, 500, and 750 micro g/rat) on sexual receptivity and paced mating behavior in rats primed with estradiol benzoate (EB) in combination with progesterone (P). Experiments 2 and 3 compared the display of sexual behaviors in rats primed with EB+P or EB alone and administered either 250 micro g ICI (Experiment 2) or 500 micro g ICI (Experiment 3). Experiment 4 tested the effects of ICI (250 and 500 micro g) on the expression of estrogen-induced progestin receptors in the uterus. ICI did not affect the display of sexual receptivity in any experiment. In rats primed with EB+P, paced mating behavior was altered by the 500 and 750 micro g, but not the 250 micro g, doses of ICI. The lowest (250 micro g) dose of ICI did alter paced mating behavior in rats primed with EB alone. The effects of ICI on paced mating behavior were manifested by a substantial lengthening of contact-return latencies following intromissions and ejaculations. The percentage of exits were not affected by ICI. Estrogen stimulation of uterine weight and induction of uterine progestin receptors was suppressed by ICI (250 and 500 micro g). ICI effects on paced mating behavior in hormone-primed female rats are likely to reflect antiestrogenic actions in the periphery, including interference with the estrogen induction of progestin receptors.

Encouragement from Jupiter for Europe's Titan Probe

NASA Astrophysics Data System (ADS)

1996-04-01

Huygens will transmit scientific information for 150 minutes, from the outer reaches of Titan's cold atmosphere and all the way down to its enigmatic surface. For comparison, the Jupiter Probe radioed scientific data for 58 minutes as it descended about 200 kilometres into the outer part of the atmosphere of the giant planet. The parachutes controlling various stages of Huygens' descent will rely upon a system for deployment designed and developed in Europe that is nevertheless similar to that used by the Jupiter Probe. The elaborate sequence of operations in Huygens worked perfectly during a dramatic drop test from a stratospheric balloon over Sweden in May 1995, which approximated as closely as possible to events on Titan. The performance of the American Probe at Jupiter renews the European engineers' confidence in their own descent control system, and also in the lithium sulphur-dioxide batteries which were chosen to power both Probes. "The systems work after long storage in space," comments Hamid Hassan, ESA's Project Manager for Huygens. "Huygens will spend seven years travelling to Saturn's vicinity aboard the Cassini Orbiter. The Jupiter Probe was a passenger in Galileo for six years before its release, so there is no reason to doubt that Huygens will work just as well." Huygens will enter the outer atmosphere of Titan at 20,000 kilometres per hour. A heat shield 2.7 metres in diameter will withstand the friction and slow the Probe to a speed at which parachutes can be deployed. The size of the parachute for the main phase of the descent is chosen to allow Huygens to reach the surface in about 2 hours. The batteries powering Huygens will last for about 21/2 hours. Prepared for surprises A different perspective on the Jupiter Probe comes from Jean-Pierre Lebreton, ESA's Project Scientist for Huygens. The results contradicted many preconceptions of the Galileo scientists, particularly about the abundance of water and the structure of cloud layers. Arguments

The shadow of Saturn's icy satellites in the E ring

NASA Astrophysics Data System (ADS)

Schmidt, J.; Sremcevic, M.

2008-09-01

We analyze shadows that Saturnian satellites cast in the E ring, a faint, broad dust ring composed of icy grains. The brightness contrast of a moon's shadow relative to the surrounding ring allows to infer local properties of the size distribution of ring particles. We derive the shadow contrast from a large number of Cassini images of Enceladus taken in various filters in a range of phase angles 144 to 164 degrees. For Tethys and Dione we identify a clear shadow in images with phase angles larger than 160 degrees. From the data we obtain the number density of E ring grains at the orbits of Tethys and Dione relative to the one near Enceladus. The latter we constrain from the variation of the shadow contrast with color and phase angle. From the Enceladus data we construct the phase curve of the E ring dust between 144 and 164 degrees. We compare to data obtained from Earth-bound observations by de Pater et al 2004 and in situ measurements by the Cosmic Dust Analyzer onboard Cassini.

Broad-search algorithms for finding triple-and quadruple-satellite-aided captures at Jupiter from 2020 to 2080

NASA Astrophysics Data System (ADS)

Lynam, Alfred E.

2015-04-01

Multiple-satellite-aided capture is a -efficient technique for capturing a spacecraft into orbit at Jupiter. However, finding the times when the Galilean moons of Jupiter align such that three or four of them can be encountered in a single pass is difficult using standard astrodynamics algorithms such as Lambert's problem. In this paper, we present simple but powerful techniques that simplify the dynamics and geometry of the Galilean satellites so that many of these triple- and quadruple-satellite-aided capture sequences can be found quickly over an extended 60-year time period from 2020 to 2080. The techniques find many low-fidelity trajectories that could be used as initial guesses for future high-fidelity optimization. Results indicate the existence of approximately 3,100 unique triple-satellite-aided capture trajectories and 6 unique quadruple-satellite-aided capture trajectories during the 60-year time period. The entire search takes less than one minute of computational time.

95 Minutes Over Jupiter

NASA Image and Video Library

2017-09-28

This sequence of color-enhanced images shows how quickly the viewing geometry changes for NASA's Juno spacecraft as it swoops by Jupiter. The images were obtained by JunoCam. Once every 53 days, Juno swings close to Jupiter, speeding over its clouds. In just two hours, the spacecraft travels from a perch over Jupiter's north pole through its closest approach (perijove), then passes over the south pole on its way back out. This sequence shows 11 color-enhanced images from Perijove 8 (Sept. 1, 2017) with the south pole on the left (11th image in the sequence) and the north pole on the right (first image in the sequence). The first image on the right shows a half-lit globe of Jupiter, with the north pole approximately at the upper center of the image close to the terminator -- the dividing line between night and day. As the spacecraft gets closer to Jupiter, the horizon moves in and the range of visible latitudes shrinks. The second and third images in this sequence show the north polar region rotating away from the spacecraft's field of view while the first of Jupiter's lighter-colored bands comes into view. The fourth through the eighth images display a blue-colored vortex in the mid-southern latitudes near Points of Interest "Collision of Colours," "Sharp Edge," "Caltech, by Halka," and "Structure01." The Points of Interest are locations in Jupiter's atmosphere that were identified and named by members of the general public. Additionally, a darker, dynamic band can be seen just south of the vortex. In the ninth and tenth images, the south polar region rotates into view. The final image on the left displays Jupiter's south pole in the center. From the start of this sequence of images to the end, roughly 1 hour and 35 minutes elapsed. https://photojournal.jpl.nasa.gov/catalog/PIA21967

Jupiter's evolution with primordial composition gradients

NASA Astrophysics Data System (ADS)

Vazan, Allona; Helled, Ravit; Guillot, Tristan

2018-02-01

Recent formation and structure models of Jupiter suggest that the planet can have composition gradients and not be fully convective (adiabatic). This possibility directly affects our understanding of Jupiter's bulk composition and origin. In this Letter we present Jupiter's evolution with a primordial structure consisting of a relatively steep heavy-element gradient of 40 M⊕. We show that for a primordial structure with composition gradients, most of the mixing occurs in the outer part of the gradient during the early evolution (several 107 yr), leading to an adiabatic outer envelope (60% of Jupiter's mass). We find that the composition gradient in the deep interior persists, suggesting that 40% of Jupiter's mass can be non-adiabatic with a higher temperature than the one derived from Jupiter's atmospheric properties. The region that can potentially develop layered convection in Jupiter today is estimated to be limited to 10% of the mass. Movies associated to Figs. 1-3 are available at http://https://www.aanda.org

Jupiter Blues

NASA Image and Video Library

2017-11-30

See Jovian clouds in striking shades of blue in this new view taken by NASA's Juno spacecraft. The Juno spacecraft captured this image when the spacecraft was only 11,747 miles (18,906 kilometers) from the tops of Jupiter's clouds -- that's roughly as far as the distance between New York City and Perth, Australia. The color-enhanced image, which captures a cloud system in Jupiter's northern hemisphere, was taken on Oct. 24, 2017 at 10:24 a.m. PDT (1:24 p.m. EDT) when Juno was at a latitude of 57.57 degrees (nearly three-fifths of the way from Jupiter's equator to its north pole) and performing its ninth close flyby of the gas giant planet. The spatial scale in this image is 7.75 miles/pixel (12.5 kilometers/pixel). Because of the Juno-Jupiter-Sun angle when the spacecraft captured this image, the higher-altitude clouds can be seen casting shadows on their surroundings. The behavior is most easily observable in the whitest regions in the image, but also in a few isolated spots in both the bottom and right areas of the image. Citizen scientists Gerald Eichstädt and Seán Doran processed this image using data from the JunoCam imager. https://photojournal.jpl.nasa.gov/catalog/PIA21972

Europa's Broken Ice

NASA Technical Reports Server (NTRS)

1996-01-01

Jupiter's moon Europa, as seen in this image taken June 27, 1996 by NASA's Galileo spacecraft, displays features in some areas resembling ice floes seen in Earth's polar seas. Europa, about the size of Earth's moon, has an icy crust that has been severely fractured, as indicated by the dark linear, curved, and wedged-shaped bands seen here. These fractures have broken the crust into plates as large as 30 kilometers (18.5 miles) across. Areas between the plates are filled with material that was probably icy slush contaminated with rocky debris. Some individual plates were separated and rotated into new positions. Europa's density indicates that it has a shell of water ice as thick as 100 kilometers (about 60 miles), parts of which could be liquid. Currently, water ice could extend from the surface down to the rocky interior, but the features seen in this image suggest that motion of the disrupted icy plates was lubricated by soft ice or liquid water below the surface at the time of disruption. This image covers part of the equatorial zone of Europa and was taken from a distance of 156,000 kilometers (about 96,300 miles) by the solid-state imager camera on the Galileo spacecraft. North is to the right and the sun is nearly directly overhead. The area shown is about 360 by 770 kilometers (220-by-475 miles or about the size of Nebraska), and the smallest visible feature is about 1.6 kilometers (1 mile) across. The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.

Jupiter Eye to Io

NASA Image and Video Library

2000-12-12

This image taken by NASA Cassini spacecraft on Dec. 1, 2000, shows details of Jupiter Great Red Spot and other features that were not visible in images taken earlier, when Cassini was farther from Jupiter.

Cratering at the Icy Satellites: Experimental Insights

NASA Astrophysics Data System (ADS)

Bruck Syal, M.; Schultz, P. H.

2013-12-01

Impact cratering processes play a central role in shaping the evolution of icy satellites and in guiding interpretations of various geologic features at these bodies. Accurate reconstruction of icy satellite histories depends in large part upon observed impact crater size-frequency distributions. Determining the extent of impact-induced thermal processing and the retention rates for impact-delivered materials of interest, e.g. organics, at these outer solar system moons is of fundamental importance for assessing their habitability and explaining differing geophysical histories. Hence, knowledge of how the impact process operates in ices or ice-rich materials is critically important. Recent progress in the development of water equations of state, coupled with increasingly efficient 3-D hydrocode calculations, has been used to construct careful numerical studies of melt and vapor generation for water ice targets. Complementary to this approach is experimental work to constrain the effects of differing ice target conditions, including porosity, rock mass fraction, and impact angle. Here we report on results from hypervelocity impact experiments (v~5.5 km/s) into water ice targets, performed at the NASA Ames Vertical Gun Range (AVGR). The setup at the AVGR allows for the use of particulate targets, which is useful for examining the effects of target porosity. Photometry and geophysical modeling both suggest that regolith porosity at the icy satellites is significant. We use a combination of half-space and quarter-space geometries, enabling analysis of the impact-generated vapor plume (half-space geometry), along with shock wave and transient crater growth tracking in a cross-sectional view (quarter-space geometry). Evaluating the impact-generated vapor from porous (φ = 0.5) and non-porous water ice targets provides an extension to previously published vapor production results for dolomite and CO2 ice targets. For the case of a 90 degree impact into porous ice, we

Proton irradiation of the CIS115 for the JUICE mission

NASA Astrophysics Data System (ADS)

Soman, M. R.; Allanwood, E. A. H.; Holland, A. D.; Winstone, G. P.; Gow, J. P. D.; Stefanov, K.; Leese, M.

2015-09-01

The CIS115 is one of the latest CMOS Imaging Sensors designed by e2v technologies, with 1504x2000 pixels on a 7 μm pitch. Each pixel in the array is a pinned photodiode with a 4T architecture, achieving an average dark current of 22 electrons pixel-1 s-1 at 21°C measured in a front-faced device. The sensor aims for high optical sensitivity by utilising e2v's back-thinning and processing capabilities, providing a sensitive silicon thickness approximately 9 μm to 12 μm thick with a tuned anti-reflective coating. The sensor operates in a rolling shutter mode incorporating reset level subtraction resulting in a mean pixel readout noise of 4.25 electrons rms. The full well has been measured to be 34000 electrons in a previous study, resulting in a dynamic range of up to 8000. These performance characteristics have led to the CIS115 being chosen for JANUS, the high-resolution and wide-angle optical camera on the JUpiter ICy moon Explorer (JUICE). The three year science phase of JUICE is in the harsh radiation environment of the Jovian magnetosphere, primarily studying Jupiter and its icy moons. Analysis of the expected radiation environment and shielding levels from the spacecraft and instrument design predict the End Of Life (EOL) displacement and ionising damage for the CIS115 to be equivalent to 1010 10 MeV protons cm-2 and 100 krad(Si) respectively. Dark current and image lag characterisation results following initial proton irradiations are presented, detailing the initial phase of space qualification of the CIS115. Results are compared to the pre-irradiation performance and the instrument specifications and further qualification plans are outlined.

Two Dimensional Viscoelastic Stress Analysis of a Prototypical JIMO Turbine Wheel

NASA Technical Reports Server (NTRS)

Gayda, John; Gabb, Timothy

2005-01-01

The designers of the Jupiter Icy Moons Orbiter (JIMO) are investigating the potential of nuclear powered-electric propulsion technology to provide deep space propulsion. In one design scenario a closed-Brayton-cycle power converter is used to convert thermal energy from a nuclear reactor to electrical power for the spacecraft utilizing an inert gas as the working fluid to run a turboalternator as described in L.S. Mason, "A Power Conversion for the Jupiter Icy Moons Orbiter," Journal of Propulsion and Power, vol. 20, no. 5, pp. 902-910. A key component in the turboalternator is the radial flow turbine wheel which may be fabricated from a cast superalloy. This turbine wheel is envisioned to run continuously over the life of the mission, which is anticipated to be about ten years. This scenario places unusual material requirements on the turbine wheel. Unlike the case of terrestrial turbine engines, fatigue, associated with start-up and shut-down of the engine, foreign-object damage, and corrosion issues are insignificant and thus creep issues become dominate. The purpose of this paper is to present estimates for creep growth of a prototypical JIMO turbine wheel over a ten year life. Since an actual design and bill of materials does not exist, the results presented in this paper are based on preliminary concepts which are likely to evolve over time. For this reason, as well as computational efficiency, a simplified 2-D, in lieu of a 3-D, viscoelastic, finite element model of a prototypical turbine wheel will be utilized employing material properties for the cast superalloy MAR-M247. The creep data employed in this analysis are based on preliminary data being generated at NASA Glenn Research Center.