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Searching for Lunar Water: The Lunar Volatile Resources Analysis Package

The ESA Lunar Lander has been conceived to demonstrate an autonomous landing capability. Once safely on the Moon the scientific payload will conduct investigations aimed at preparing the way for human exploration. As part of the provisional payload an instrument known as The Lunar Volatile Resources Analysis Package (L-VRAP) will analyse surface and exospheric volatiles. The presence and abundance of lunar water is an important consideration for ISRU (In Situ Resource Utilisation) since this is likely to be part of a strategy for supporting long-term human exploration of the Moon.

Morse, A. D.↗

MAVEN - Mars Atmosphere and Volatile EvolutioN Mission

NASA's MAVEN mission (to be launched in late 2013) is the first mission to Mars devoted to sampling all of the upper atmosphere neutral and plasma environments, including the well-mixed atmosphere, the exosphere, ionosphere, outer magnetosphere and near-Mars solar wind. It will fill in some measurement gaps remaining from the successful Mars Global Surveyor and the on-going Mars Express missions. The primary science objectives of MAVEN are: 1. Provide a comprehensive picture of the present state of the upper atmosphere and ionosphere of Mars; 2. Understand the processes controlling the present state; and 3. Determine how loss of volatiles to outer space in the present epoch varies with changing solar condition - EUY, solar wind and interplanetary magnetic field measurements will provide the varying solar energy inputs into the system. Knowing how these processes respond to the Sun's energy inputs in the current epoch will provide a framework for projecting atmospheric processes back in time to profile MARS' atmospheric evolution and to explore "where the water went", A description will be given of the science objectives, the instruments, and the current status of the project, emphasizing the value of having collaborations between the MAVEN project and the Mars upper atmosphere science community.

Grebowsky, Joseph M.↗

Astrobiological Journeys to and from the South Polar Sea of Enceladus - Bidirectional Interactions with the Saturn Magnetosphere

The spectacularly cryovolcanic moon Enceladus is a major source of plasma for the Saturn magnetosphere via ionization of the ejected molecular species and ice grains. Field-aligned plasma flows from the Enceladus environment visibly impact the moon's magnetic footpoint in Saturn's polar auroral region, while water group and other ions from the moon emissions diffuse radially throughout the magnetosphere and may be the dominant source of oxygen for Titan's oxygen-poor upper atmosphere. But the moon-magnetosphere interaction is bidirectional in the sense that the moon surface is globally exposed to constant irradiation by the returning magnetospheric ions and by energetic electrons from the field-aligned and radially diffusing populations. The returning ion source operates both on global scales of the magnetosphere and locally for highly reactive species produced in the ejecta plume. All of these sources likely combine to produce a highly oxidized global surface layer. Since plasma electrons and ions are cooled by interaction with neutral gas and E-ring ice grains from Enceladus, the moon emissions have a governing effect on the seed populations of energetic particles that irradiate the surface. The proposed subsurface polar sea and transient crustal overturn in the south polar region could bring the polar surface oxidants into contact with hydrocarbons and ammonia to make oxidation product gases contributing to the cryovolcanic jets, a process first proposed by Cooper et al. (Plan. Sp. Sci., 2009). As has been previously suggested for Europa, the 'oxidants could contribute to enhanced astrobiological potential of Enceladus, perhaps even higher than for Europa where organic hydrocarbons have not yet been directly detected. Unlike Europa, Enceladus shows no sign of an oxygen-dominated exosphere that could otherwise be indicative of extreme surface and interior oxidation inhibiting the detectable survival and evolution of complex organics.

Cooper, John F.↗

The Plasma Environment at Mercury

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

Raines, James M.↗

AXIOM: Advanced X-Ray Imaging Of the Magnetosheath

AXIOM (Advanced X-ray Imaging Of the Magnetosphere) is a concept mission which aims to explain how the Earth's magnetosphere responds to the changing impact of the solar wind using a unique method never attempted before; performing wide-field soft X-ray imaging and spectroscopy of the magnetosheath. magnetopause and bow shock at high spatial and temporal resolution. Global imaging of these regions is possible because of the solar wind charge exchange (SWCX) process which produces elevated soft X-ray emission from the interaction of high charge-state solar wind ions with primarily neutral hydrogen in the Earth's exosphere and near-interplanetary space.

Sembay, S.↗

Regarding the Possible Generation of a Lunar Nightside Exo-Ionosphere

The non-condensing neutral helium exosphere is at its most concentrated levels on the cold lunar nightside. We show herein that these He atoms are susceptible to impact ionization from primary and secondary electrons flowing in the vicinity of the negatively-charged nightside lunar surface. The secondary electron beams are a relatively recent discovery and are found to be emitted from the nightside surface at energies consistent with the negative surface potential. The effect is to create an electron impact-created ionosphere in nightside regions. possibly especially potent within polar craters.

Farrell, W. M.↗

Two Azimuthally Separated Regions of Cusp Ion Injection Observed via Energetic Neutral Atoms

The low-energy neutral atom (LENA) imager on the IMAGE spacecraft can detect energetic neutral atoms produced by ion injection into the cusp through a charge exchange with the Earth's hydrogen exosphere. We examined the occurrence of the LENA cusp signal during positive IMF B(sub z) in terms of the arrival direction and the IMF clock angle theta(sub CA). Results of statistical analyses show that the occurrence frequency is high on the postnoon side when theta(sub CA) is between approximately 20 degrees and approximately 50 degrees. This is ascribed to ion injection caused by cusp reconnection typical of positive IMF B(sub z). Our results also show that there is another situation of high occurrence frequency, which can be identified with theta(sub CA) of approximately 30 degrees to approximately 80 degrees. When theta(sub CA) is relatively large (60 degrees - 80 degrees), occurrence frequencies are high at relatively low latitudes over a wide extent spanning both prenoon and postnoon sectors. This feature suggests that the ion injection is caused by reconnection at the dayside magnetopause. Its postnoon side boundary shifts toward the prenoon as theta(sub CA) decreases. When theta(sub CA) is less than approximately 50 degrees, the high occurrence frequency exists well inside the prenoon sector, which is azimuthally separated from the postnoon region ascribed to cusp reconnection. The prenoon region, which is thought due to ion injection caused by dayside reconnection, may explain the recent report that proton aurora brightening occurs in the unanticipated prenoon sector of the northern high-latitude ionosphere for IMF B(sub y) greater than 0 and B(sub z) greater than 0.

Abe, M.↗

Saturn's Magnetosphere Interaction with Titan for T9 Encounter: 3D Hybrid Modeling and Comparison with CAPS Observations

Global dynamics of ionized and neutral gases in the environment of Titan plays an important role in the interaction of Saturn s magnetosphere with Titan. Several hybrid simulations of this problem have already been done (Brecht et al., 2000; Kallio et al., 2004; Modolo et al., 2007a; Simon et al., 2007a, 2007b; Modolo and Chanteur, 2008). Observational data from CAPS for the T9 encounter (Sittler et al., 2009) indicates an absence of O(+) heavy ions in the upstream that change the models of interaction which were discussed in current publications (Kallio et al., 2004; Modolo et al., 2007a; Simon et al., 2007a, 2007b; Ma et al., 2007; Szego et al., 2007). Further analysis of the CAPS data shows very low density or even an absence of H(+) ions in upstream. In this paper we discuss two models of the interaction of Saturn s magnetosphere with Titan: (A) high density of H(+) ions in the upstream flow (0.1/cu cm), and (B) low density of H(+) ions in the upstream flow (0.02/cu cm). The hybrid model employs a fluid description for electrons and neutrals, whereas a particle approach is used for ions. We also take into account charge-exchange and photoionization processes and solve self-consistently for electric and magnetic fields. The model atmosphere includes exospheric H(+), H(2+), N(2+)and CH(4+) pickup ion production as well as an immobile background ionosphere and a shell distribution for active ionospheric ions (M(sub i)=28 amu). The hybrid model allows us to account for the realistic anisotropic ion velocity distribution that cannot be done in fluid simulations with isotropic temperatures. Our simulation shows an asymmetry of the ion density distribution and the magnetic field, including the formation of Alfven wing-like structures. The results of the ion dynamics in Titan s environment are compared with Cassini T9 encounter data (CAPS).

Lipatov, A. S.↗

MESSENGER Observations of the Spatial Distribution of Planetary Ions Near Mercury

Global measurements by MESSENGER of the fluxes of heavy ions at Mercury, particularly sodium (Na(+)) and oxygen (O(+)), exhibit distinct maxima in the northern magnetic-cusp region, indicating that polar regions are important sources of Mercury's ionized exosphere, presumably through solar-wind sputtering near the poles. The observed fluxes of helium (He(+)) are more evenly distributed, indicating a more uniform source such as that expected from evaporation from a helium-saturated surface. In some regions near Mercury, especially the nightside equatorial region, the Na(+) pressure can be a substantial fraction of the proton pressure.

Zurbuchen, Thomas H.↗

Kinetic and Potential Sputtering of Lunar Regolith: The Contribution of the Heavy Highly Charged (Minority) Solar Wind Ions

Solar wind sputtering of the lunar surface helps determine the composition of the lunar exosphere and contributes to surface weathering. To date, only the effects of the two dominant solar wind constituents, H+ and He+, have been considered. The heavier, less abundant solar wind constituents have much larger sputtering yields because they have greater mass (kinetic sputtering) and they are highly charged (potential sputtering) Their contribution to total sputtering can therefore be orders of magnitude larger than their relative abundances would suggest

Meyer, F. W.↗

Ringing After a High-Energy Collision: Ambipolar Oscillations During Impact Plasma Expansion

High-velocity impacts on the Moon and other airless bodies deliver energy and material to the lunar surface and exosphere. The target and i mpactor material may become vaporized and ionized to form a collision al plasma that expands outward and eventually becomes collisionless. In the present work, kinetic simulations of the later collision less stage of impact plasma expansion are performed. Attention is paid to characterizing "ambipolar oscillations" in which thermodynamic distur bances propagate outward to generate "ringing" within the expanding e lectron cloud, which could radiate an electromagnetic signature of lo cal plasma conditions. The process is not unlike a beam-plasma intera ction, with the perturbing electron population in the present case ac ting as a highly thermal "beam" that resonates along the expanding de nsity gradient. Understanding the electromagnetic aspects of impact p lasma expansion could provide insight into the lasting effects of nat ural, impact-generated currents on airless surfaces and charging haza rds to human exploration infrastructure and instrumentation.

Zimmerman, M. I.↗

EXOS and the Evolution of WINCS

EXOS is the charged-particle spectrometer on EXOCUBE that will measure the H/He/O and H+ /He+ /0+ densities and temperatures in the exosphere. Its basic approach is based on WINCS; however, EXOS gave the impetus for improvements that led to the 2nd generation WINCS. Beginning with a brief description of the WINCS methodology for ionosphere-thermosphere measurements, lessons learned from the first generation WINCS are summarized as introduction to the design of EXOS. The EXOS design is then presented and discussed.

Herrero, Fred↗

Calibration of the Neutral Mass Spectrometer for the Lunar Atmosphere and Dust Environment Explorer

Science objectives of the LADEE Mission are to (1) determine the composition, and time variability of the tenuous lunar atmosphere and (2) to characterize the dust environment and its variability. These studies will extend the in-situ characterization of the environment that were carried out decades ago with the Apollo missions and a variety of ground based studies. The focused LADEE measurements will enable a more complete understanding of dust and gas sources and sinks. Sources of gas include UV photo-stimulated desorption, sputtering by plasma and micrometeorites, as well as thermal release of species such as argon from the cold service or venting from the lunar interior. Sinks include recondensation on the surface and escape through a variety of mechanisms. The LADEE science payload consists of an Ultraviolet Spectrometer, a Neutral Mass Spectrometer, and a Dust Detector. The LADEE orbit will include multiple passes at or below 50 km altitude and will target repeated sampling at the sunrise terminator where exospheric density will be highest for some thermally released species. The science mission will be implemented in approximately three months to allow measurements to be made over a period of one or more lunations In addition to the science mission NASA will use this mission to demonstrate optical communication technology away from low Earth orbit.

Mahaffy, P. R.↗

Overview of the LADEE Ultraviolet-visible Spectrometer: Design, Performance and Planned Operations

The Lunar Atmosphere and Dust Environment Explorer (LADEE) is an orbital lunar science mission currently under development to address the goals of the 2003 National Research Council decadal survey, the Lunar Exploration Analysis Group Roadmap, and the "Scientific Context for Exploration of the Moon" (SCEM) report, and has been recommended for execution by the 2011 Planetary Missions Decadal Survey. The mission s focus is to study the pristine state of the lunar atmosphere and dust environment prior to possible lunar exploration activities by countries, including the United States, China, India, and Japan, among others. Activity on the lunar surface has the potential of altering the tenuous lunar atmosphere, but changing the type and concentration of gases in the atmosphere. Before these activities occur it is important to make measurements of the current lunar atmosphere in its unmodified state. LADEE will determine the composition of the lunar atmosphere and investigate the processes that control its distribution and variability, including sources, sinks, and surface interactions. It will monitor variations in known gases, such as sodium, potassium, argon and helium, and will search for other, as-yet-undetected gases of both lunar and extra-lunar origin. LADEE will also determine whether dust is present in the lunar exosphere, and reveal the processes that contribute to its sources and variability. Launch is planned for August, 2013.

Colaprete, A.↗

Lunar Pickup Ions Observed by ARTEMIS: Spatial and Temporal Distribution and Constraints on Species and Source Locations

ARTEMIS observes pickup ions around the Moon, at distances of up to 20,000 km from the surface. The observed ions form a plume with a narrow spatial and angular extent, generally seen in a single energy/angle bin of the ESA instrument. Though ARTEMIS has no mass resolution capability, we can utilize the analytically describable characteristics of pickup ion trajectories to constrain the possible ion masses that can reach the spacecraft at the observation location in the correct energy/angle bin. We find that most of the observations are consistent with a mass range of approx. 20-45 amu, with a smaller fraction consistent with higher masses, and very few consistent with masses below 15 amu. With the assumption that the highest fluxes of pickup ions come from near the surface, the observations favor mass ranges of approx. 20-24 and approx. 36-40 amu. Although many of the observations have properties consistent with a surface or near-surface release of ions, some do not, suggesting that at least some of the observed ions have an exospheric source. Of all the proposed sources for ions and neutrals about the Moon, the pickup ion flux measured by ARTEMIS correlates best with the solar wind proton flux, indicating that sputtering plays a key role in either directly producing ions from the surface, or producing neutrals that subsequently become ionized.

Artemis↗

Earth Observation from Space - The Issue of Environmental Sustainability

Remote sensing scientists work under assumptions that should not be taken for granted and should, therefore, be challenged. These assumptions include the following: 1. Space, especially Low Earth Orbit (LEO), will always be available to governmental and commercial space entities that launch Earth remote sensing missions. 2. Space launches are benign with respect to environmental impacts. 3. Minimization of Type 1 error, which provides increased confidence in the experimental outcome, is the best way to assess the significance of environmental change. 4. Large-area remote sensing investigations, i.e. national, continental, global studies, are best done from space. 5. National space missions should trump international, cooperative space missions to ensure national control and distribution of the data products. At best, all of these points are arguable, and in some cases, they're wrong. Development of observational space systems that are compatible with sustainability principles should be a primary concern when Earth remote sensing space systems are envisioned, designed, and launched. The discussion is based on the hypothesis that reducing the environmental impacts of thedata acquisition step,which is at the very beginning of the information streamleading to decision and action, will enhance coherence in the information streamand strengthen the capacity of measurement processes to meet their stated functional goal, i.e. sustainable management of Earth resources. We suggest that unconventional points of view should be adopted and when appropriate, remedial measures considered that could help to reduce the environmental footprint of space remote sensing and of Earth observation and monitoring systems in general. This article discusses these five assumptions inthe contextof sustainablemanagementof Earth's resources. Takingeachassumptioninturn,we find the following: (1) Space debris may limit access to Low Earth Orbit over the next decades. (2) Relatively speaking, given that they're rare event, space launches may be benign, but study is merited on upper stratospheric and exospheric layers given the chemical activity associated with rocket combustion by-products. (3) Minimization of Type II error should be considered in situations where minimization of Type I error greatly hampers or precludes our ability to correct the environmental condition being studied. (4) In certain situations, airborne collects may be less expensive and more environmentally benign, and comparative studies should be done to determine which path is wisest. (5) International cooperation and data sharing will reduce instrument and launch costs and mission redundancy. Given fiscal concerns of most of the major space agencies e e.g. NASA, ESA, CNES e it seems prudent to combine resources.

Earth observation systems↗

Mass Dependency of Isotope Fractionation of Gases Under Thermal Gradient and Its Possible Implications for Planetary Atmosphere Escaping Process

Physical processes that unmix elements/isotopes of gas molecules involve phase changes, diffusion (chemical or thermal), effusion and gravitational settling. Some of those play significant roles for the evolution of chemical and isotopic compositions of gases in planetary bodies which lead to better understanding of surface paleoclimatic conditions, e.g. gas bubbles in Antarctic ice, and planetary evolution, e.g. the solar-wind erosion induced gas escaping from exosphere on terrestrial planets.. A mass dependent relationship is always expected for the kinetic isotope fractionations during these simple physical processes, according to the kinetic theory of gases by Chapman, Enskog and others [3-5]. For O-bearing (O16, -O17, -O18) molecules the alpha O-17/ alpha O-18 is expected at 0.5 to 0.515, and for S-bearing (S32,-S33. -S34, -S36) molecules, the alpha S-33/ αlpha S-34 is expected at 0.5 to 0.508, where alpha is the isotope fractionation factor associated with unmixing processes. Thus, one isotope pair is generally proxied to yield all the information for the physical history of the gases. However, we recently] reported the violation of mass law for isotope fractionation among isotope pairs of multiple isotope system during gas diffusion or convection under thermal gradient (Thermal Gradient Induced Non-Mass Dependent effect, TGI-NMD). The mechanism(s) that is responsible to such striking observation remains unanswered. In our past studies, we investigated polyatomic molecules, O2 and SF6, and we suggested that nuclear spin effect could be responsible to the observed NMD effect in a way of changing diffusion coefficients of certain molecules, owing to the fact of negligible delta S-36 anomaly for SF6.. On the other hand, our results also showed that for both diffusion and convection under thermal gradient, this NMD effect is increased by lower gas pressure, bigger temperature gradient and lower average temperature, which indicate that the nuclear spin effect may not be the significant contributor as the energies involved in the hyperfine effect are much smaller than those with molecular collisions, especially under convective conditions.

Sun, Tao↗

Energetic Particles Dynamics in Mercury's Magnetosphere

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

Energetic particles↗