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Abstract:

The Lunar Vulkan Imaging and Spectroscopy Explorer (Lunar-VISE) was selected for a Commercial Lunar Payload Services (CLPS) delivery to the Gruithuisen domes region of the Moon as part of NASA’s Payloads and Research Investigation on the Surface of the Moon program. The Lunar-VISE instrument payload is designed to investigate the compositional and thermophysical properties of dome materials in order to understand how late-stage silicic volcanism occurred on the Moon. Selection of a landing site required balancing science and exploration goals with the safety requirements for landing and rover trafficability. Science required access to boulders, potential exposures of bedrock, and if possible, rover access to the dome edge to enable observations of the surrounding maria. Safety considerations included landing hazards, maintenance of line-of-sight communications between the lander and rover, and any early morning or late afternoon shadows that would limit the mission duration. After consideration of several candidate landing sites, a 100-meter diameter landing ellipse centered on 36.45715°N, 319.20398°E, was selected near the edge of a topographic step and blocky ejecta crater (recently named Mareta) near the summit of Mons Gruithuisen Gamma. This location enables access to a field of boulders excavated by a relatively fresh impact providing a diversity of boulders for investigations, as well as views to the surrounding mare and Mons Gruithuisen Delta dome off of the dome edge via only a short rover traverse outside the landing ellipse (traverse <100 m) while meeting safety requirements in accord with the CLPS risk posture.

Abstract:

We present a systematic detection and characterization of mesoscale atmospheric gravity waves in Martian clouds using High Resolution Stereo Camera (HRSC) imagery from Mars Express during Martian Years 34–37. Gravity wave packets were identified in the HRSC Cloud Atlas data set, and their morphology (horizontal wavelength, packet width/length, orientation) was measured on map-projected products. Cloud top altitudes were derived from blue-green parallax using HRSC's multi-channel imaging geometry. For a subset of stereo–temporal “brooming” pairs separated by (Formula presented.) min, horizontal winds were derived by manual feature tracking, enabling direct estimates of observed and intrinsic phase speeds and implied vertical wavelengths at the packet scale. We cataloged 146 packets, of which 114 were morphologically characterized, measured 100 cloud top heights, and 11 had full dynamical characterization. Horizontal wavelengths span 2–117 km with an average of 29 km. Cloud tops show a dominant concentration between ≈15 and 40 km, and a less frequent extension to 60–100 km, with uncertainty ∼3–10 km, and clear spatial and seasonal variability. For the dynamical subset, observed phase speeds are 2.0–8.6 m/s, intrinsic phase speeds are 0.4–6.2 m/s, and implied vertical wavelengths are 0.2–3.4 km. These results demonstrate that HRSC repeat-track imaging enables packet-scale constraints on intrinsic gravity wave drag and mesoscale dynamics in Martian circulation models.

Abstract:

Radio occultation (RO) is a very powerful technique as it offers great opportunities to study planetary atmospheres, providing information about their ionosphere and neutral atmosphere. Standard methods use a radio link at S and/or X bands between a spacecraft orbiting a planet and a ground station on the Earth. At Mars, such measurements have been conducted since the 60s. Three most recent data sets are from Mars Global Surveyor, Mars Express and the Mars Atmosphere and Volatile Evolution satellites. Furthermore, the possibility to obtain information about the Martian atmosphere with mutual RO events, using data from NASA Mars Odyssey and Mars Reconnaissance Orbiters, has been demonstrated by NASA scientists in 2015. Taking advantage of two European spacecraft in orbit around Mars, the ESA is currently performing an experiment that consists of mutual radio occultations between Mars Express (MEX) and ExoMars Trace Gas Orbiter (TGO). In preparation for MEX and TGO data inversion and analysis, a simulation-based strategy has been adopted and an algorithm, including the associated software, able to retrieve vertical electron density profiles from Doppler shift measurements has been implemented and validated. Subsequently, to test the mentioned algorithm with experimental data, the same three mutual RO events considered by NASA scientists have been re-processed. In this work, the research activities carried out through the simulation studies and the results obtained by the application of the mentioned inversion algorithm to experimental data are presented.

Abstract:

The main belt asteroid (52246) Donaldjohanson (DJ) is a likely member of the Erigone asteroid family. This implies that DJ is a fragment of a larger parent body that was destroyed in a collision about 155 million years ago. We report observations taken during a flyby of DJ by the Lucy spacecraft. We found that DJ is composed of two heavily cratered lobes, connected by a smoother neck, with overall dimensions 8.8 kilometers (km) by 4.4 km by 3.1 km. The crater density is consistent with the Erigone family’s age, except for craters <0.4 km, which have been preferentially erased. DJ rotates slowly in a tumbling state, likely owing to spin-down by radiative forces. Surface spectra show iron-bearing phyllosilicates, indicating moderate aqueous evolution on the parent body.

Abstract:

Remote spectroscopy is used to characterize the mineralogy and infer the history of planetary bodies. Carbonaceous asteroids, such as B‐type (101955) Bennu, represent the earliest stages of planet formation. B types have a blue (negative) spectral slope and comprise <5% of asteroids. Samples from Bennu returned by the OSIRIS‐REx spacecraft complement remote observations of this rare population. We show here, using laboratory spectra that are directly comparable to spacecraft data, that OSIRIS‐REx accurately determined Bennu's dust content and most of its surface composition. However, spectra of the asteroid exhibit stronger water absorptions than those of bulk samples, possibly due to hydrous, Mg‐rich phosphate or solar wind implantation at Bennu's uppermost surface. Bennu samples spectrally resemble the most aqueously altered carbonaceous meteorites and samples of (162173) Ryugu, indicating similarly pervasive aqueous alteration. However, one carbon‐enriched Bennu stone does not appear to have a spectral analog among Ryugu samples or meteorites. Our findings demonstrate the leverage obtained using a wide range of wavelengths and that sample analysis anchors the interpretations of remote sensing, leading to more robust characterization of planetary surface composition and evolution.