Publications

Abstract The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft landed successfully on Mars and imaged the surface to characterize the surficial geology. Here we report on the geology and subsurface structure of the landing site to aid in situ geophysical investigations. InSight landed in a degraded impact crater in Elysium Planitia on a smooth sandy, granule- and pebble-rich surface with few rocks. Superposed impact craters are common and eolian bedforms are sparse. During landing, pulsed retrorockets modified the surface to reveal a near surface stratigraphy of surficial dust, over thin unconsolidated sand, underlain by a variable thickness duricrust, with poorly sorted, unconsolidated sand with rocks beneath. Impact, eolian, and mass wasting processes have dominantly modified the surface. Surface observations are consistent with expectations made from remote sensing data prior to landing indicating a surface composed of an impact-fragmented regolith overlying basaltic lava flows.

Hematite‐bearing deposits in the Terra Meridiani region of Mars constitute the top stratum of a partially eroded layered complex that covers dissected Noachian‐aged cratered terrain. The hematite unit consists of dark plains and dunes covering a bright substrate. This substrate is fully exposed beyond the borders of the hematite‐bearing deposit and consists of polygonal ground separated by ridges or valleys, together with layered deposits that have been eroded into a variety of landforms. The complex is partially covered by a regional‐scale aeolian mantle that thickens toward the north. The hematite‐bearing stratum exhibits low albedoes, pulse widths, and intermediate thermal inertias, whereas the underlying unit exhibits high values of these parameters. Both units have spectral emissivity signatures similar to those for the low albedo cratered terrain to the south, with the addition of hematite for the top stratum. The complex is interpreted to consist of extensive plains‐forming lava flows and tephra deposits emplaced during an extensional regime and at least partially buried by an aeolian mantle. Aeolian stripping of the mantle exposed much of the complex and differentially eroded the deposits to produce the landforms existent today. Exploration of the hematite‐bearing deposits by the 2003 Mars Exploration Rover, “Opportunity,” will allow testing of the hypotheses presented since this stratum has been locally reworked into dunes that only partially cover the underlying brighter portion of the complex. In particular, the rover‐based measurements will allow us to test the extent to which the unusual remote‐sensing properties of the units indicate aqueous alteration.

BY LEND/LRO. I. G. Mitrofanov , M. L. Litvak, A. B. Sanin, A. A. Malakhov, D. V. Golovin, W. Boynton, G. Droege, G. Chin, L. Evens, K. Harshman, J. Garvin, A. Kozyrev, T. McClanahan, G. Milikh, M. Mokrousov, R. Starr, R. Sagdeev, V. Shevchenko, V. Shvetsov, V. Tret’yakov, J. Trombka, A. Varenikov and A. Vostrukhin. Institute for Space Research of Russian Academy of Science, 117997 Moscow, Russia, imitrofa@space.ru, University of Arizona, Tucson, USA, NASA Goddard Space Flight Center, Greenbelt, USA, Computer Science Corporation, Greenbelt, USA, University of Maryland, College Park, USA, Catholic University, Washington DC, USA, Sternberg Astronomical Institute of Moscow State University, Moscow, Russia, Joint Institute of Nuclear Energy, Dubna, Moscow.

The cover image incorporates high resolution stereo pairs acquired from the DigitalGlobe(R) QuickBird sensor. It shows a digital elevation model of Meteor Crater, Arizona at approximately 1.3 meter point-spacing. Image analysts used the Leica Photogrammetry Suite to produce the DEM. The outside portion was computed from two QuickBird panchromatic scenes acquired October 2006, while an Optech laser scan dataset was used for the crater s interior elevations. The crater s terrain model and image drape were created in a NASA Constellation Program project focused on simulating lunar surface environments for prototyping and testing lunar surface mission analysis and planning tools. This work exemplifies NASA s Scientific Data Purchase legacy and commercial high resolution imagery applications, as scientists use commercial high resolution data to examine lunar analog Earth landscapes for advanced planning and trade studies for future lunar surface activities. Other applications include landscape dynamics related to volcanism, hydrologic events, climate change, and ice movement.

Abstract We report the aeolian changes observed in situ by NASA's InSight lander during the first 400 sols of operations: Granule creep, saltation, dust removal, and the formation of dark surface tracks. Aeolian changes are infrequent and sporadic. However, on sols, when they do occur, they consistently appear between noon to 3 p.m., and are associated with the passage of convective vortices during periods of high vortex activity. Aeolian changes are more frequent at elevated locations, such as the top surfaces of rocks and lander footpads. InSight observed these changes using, for the first time, simultaneous in‐situ and orbital imaging and high‐frequency meteorological, seismological, and magnetic measurements. Seismometer measurements of ground acceleration constrain the timing and trajectory of convective vortex encounters, linking surface changes to source vortices. Magnetometer measurements show perturbations in magnetic field strength during the passage of convective vortices consistent with charged‐particle motion. Detachment of sand‐scale particles occurs when high background winds and vortex‐induced turbulence provide a peak surface friction wind speed above the classic saltation fluid threshold. However, detachment of dust‐ and granule‐scale particles also occurred when the surface friction wind speed remained below this threshold. This may be explained by local enhancement of the surface roughness and other effects described here and further studied in Part 2 (Baker et al., 2021). The lack of saltation and bright dust‐coated surfaces at the InSight landing site implies surface stability and the onset of particle motion may be suppressed by dust “cushioning.” This differentiates the InSight landing site from other areas on Mars that exhibit more aeolian activity.

Measurements from the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker Laser Rangefinder (NLR) indicate that asteroid 433 Eros is a consolidated body with a complex shape dominated by collisions. The offset between the asteroid's center of mass and center of figure indicates a small deviation from a homogeneous internal structure that is most simply explained by variations in mechanical structure. Regional-scale relief and slope distributions show evidence for control of topography by a competent substrate. Impact crater morphology is influenced by both gravity and structural control. Small-scale topography reveals ridges and grooves that may be generated by impact-related fracturing.

A large aperture scanning airborne lidar facility is being developed to provide important new capabilities for airborne lidar sensor systems. The proposed scanning mechanism allows for a large aperture telescope (25 in. diameter) in front of an elliptical flat (25 x 36 in.) turning mirror positioned at a 45 degree angle with respect to the telescope optical axis. The lidar scanning capability will provide opportunities for acquiring new data sets for atmospheric, earth resources, and oceans communities. This completed facility will also make available the opportunity to acquire simulated EOS lidar data on a near global basis. The design and construction of this unique scanning mechanism presents exciting technological challenges of maintaining the turning mirror optical flatness during scanning while exposed to extreme temperatures, ambient pressures, aircraft vibrations, etc.

Abstract The InSight lander carried an Instrument Deployment System (IDS) that included an Instrument Deployment Arm (IDA), scoop, five finger “claw” grapple, forearm-mounted Instrument Deployment Camera (IDC) requiring arm motion to image a target, and lander-mounted Instrument Context Camera (ICC), designed to image the workspace, and to place the instruments onto the surface. As originally proposed, the IDS included a previously built arm and flight spare black and white cameras and had no science objectives or requirements, or expectation to be used after instrument deployment (90 sols). During project development the detectors were upgraded to color, and it was recognized that the arm could be used to carry out a wide variety of activities that would enable both geology and physical properties investigations. During surface operations for two martian years, the IDA was used during major campaigns to image the surface around the lander, to deploy the instruments, to assist the mole in penetrating beneath the surface, to bury a portion of the seismometer tether, to clean dust from the solar arrays to increase power, and to conduct a surface geology investigation including soil mechanics and physical properties experiments. No other surface mission has engaged in such a sustained and varied campaign of arm and scoop activities directed at such a diverse suite of objectives. Images close to the surface and continuous meteorology measurements provided important constraints on the threshold friction wind speed needed to initiate aeolian saltation and surface creep. The IDA was used extensively for almost 22 months to assist the mole in penetrating into the subsurface. Soil was scraped into piles and dumped onto the seismometer tether six times in an attempt to bury the tether and $\sim30\%$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>∼</mml:mo> <mml:mn>30</mml:mn> <mml:mi>%</mml:mi> </mml:math> was entrained in the wind and dispersed downwind 1-2 m, darkening the surface. Seven solar array cleaning experiments were conducted by dumping scoops of soil from 35 cm above the lander deck during periods of high wind that dispersed the sand onto the panels that kicked dust off of the panels into suspension in the atmosphere, thereby increasing the power by ∼15% during this period. Final IDA activities included an indentation experiment that used the IDA scoop to push on the ground to measure the plastic deformation of the soil that complemented soil mechanics measurements from scoop interactions with the surface, and two experiments in which SEIS measured the tilt from the arm pressing on the ground to derive near surface elastic properties.

Venera Lander reflectance data are compared with high temperature spectra of the same basaltic materials. The dark, flat unoxidized basalts are still inconsistent with the Venera data in the near-infrared. Basaltic material with a ferric component, however, would satisfy both the increase in reflectance beyond 0.7 microns as well as the dark, relatively colorless character in the visible. Therefore, it is concluded that besaltic surfaces of Venus represented by these measurements either contain minerals with uncommon characteristics, or, more likely, are relatively oxidized.