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Radar evidence of subglacial liquid water on Mars
Pajola, M.; Lauro, S. E.; Pettinelli, E. +19 more
The presence of liquid water at the base of the martian polar caps has long been suspected but not observed. We surveyed the Planum Australe region using the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument, a low-frequency radar on the Mars Express spacecraft. Radar profiles collected between May 2012 and December 20…
The Source Crater of Martian Shergottite Meteorites
Poulet, François; Werner, Stephanie C.; Ody, Anouck
Absolute ages for planetary surfaces are often inferred by crater densities and only indirectly constrained by the ages of meteorites. We show that the <5 million-year-old and 55-km-wide Mojave Crater on Mars is the ejection source for the meteorites classified as shergottites. Shergottites and this crater are linked by their coinciding meteori…
Evidence of Water Vapor in Excess of Saturation in the Atmosphere of Mars
Forget, F.; Maltagliati, L.; Montmessin, F. +3 more
The vertical distribution of water vapor is key to the study of Mars’ hydrological cycle. To date, it has been explored mainly through global climate models because of a lack of direct measurements. However, these models assume the absence of supersaturation in the atmosphere of Mars. Here, we report observations made using the SPICAM (Spectroscop…
Detection of Hydrated Silicates in Crustal Outcrops in the Northern Plains of Mars
Bibring, J. -P.; Poulet, F.; Carter, J. +1 more
The composition of the ancient martian crust is a key ingredient in deciphering the environment and evolution of early Mars. We present an analysis of the composition of large craters in the martian northern plains based on data from spaceborne imaging spectrometers. Nine of the craters have excavated assemblages of phyllosilicates from ancient, N…
Subsurface Radar Sounding of the South Polar Layered Deposits of Mars
Gurnett, Donald A.; Stofan, Ellen R.; Frigeri, Alessandro +21 more
The ice-rich south polar layered deposits of Mars were probed with the Mars Advanced Radar for Subsurface and Ionospheric Sounding on the Mars Express orbiter. The radar signals penetrate deep into the deposits (more than 3.7 kilometers). For most of the area, a reflection is detected at a time delay that is consistent with an interface between th…
Martian Atmospheric Erosion Rates
Barabash, Stas; Lundin, Rickard; Fedorov, Andrei +1 more
Mars was once wet but is now dry, and the fate of its ancient carbon dioxide atmosphere is one of the biggest puzzles in martian planetology. We have measured the current loss rate due to the solar wind interaction for different species: Q(O+) = 1.6·1023 per second = 4 grams per second (g s-1), Q(O2…
Coupled Ferric Oxides and Sulfates on the Martian Surface
Mangold, N.; Sotin, C.; Bibring, J. -P. +9 more
The Mars Exploration Rover (MER), Opportunity, showed that layered sulfate deposits in Meridiani Planum formed during a period of rising acidic ground water. Crystalline hematite spherules formed in the deposits as a consequence of aqueous alteration and were concentrated on the surface as a lag deposit as wind eroded the softer sulfate rocks. On …
Radar Sounding of the Medusae Fossae Formation Mars: Equatorial Ice or Dry, Low-Density Deposits?
Stofan, Ellen R.; Clifford, Stephen M.; Orosei, Roberto +10 more
The equatorial Medusae Fossae Formation (MFF) is enigmatic and perhaps among the youngest geologic deposits on Mars. They are thought to be composed of volcanic ash, eolian sediments, or an ice-rich material analogous to polar layered deposits. The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument aboard the Mars Expr…
Density of Mars’ South Polar Layered Deposits
Zuber, Maria T.; Asmar, Sami W.; Smrekar, Suzanne E. +6 more
Both poles of Mars are hidden beneath caps of layered ice. We calculated the density of the south polar layered deposits by combining the gravity field obtained from initial results of radio tracking of the Mars Reconnaissance Orbiter with existing surface topography from the Mars Orbiter Laser Altimeter on the Mars Global Surveyor spacecraft and …
Global Mineralogical and Aqueous Mars History Derived from OMEGA/Mars Express Data
Drossart, Pierre; Korablev, Oleg; Forget, F. +43 more
Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the ``phyllocian'…