Mars Research

Current Projects

The Habitability of Mars analog low-temperature brines in the Dry Valleys, Antarctica

Sletten, R. S.; Toner, J. D.; Catling, D. C.; Liu, L.; Ming, D.; Gillespie, A.; Mushkin, A.

Abstract: The exploration of Mars is motivated in large part by the possibility that Mars may have harbored life early in its history or may have extant life in the subsurface. Because water is an essential ingredient for life, research on the processes that form liquid water is critical for understanding the habitability of Mars. To investigate the possible formation of near-surface liquid water on Mars, we are using a combination of (1) field research on shallow groundwater features in a Mars analog environment, the McMurdo Dry Valleys (MDV), and (2) theoretical modeling of brine and vapor transport in permafrost soils. The field work component of this proposal is investigating the chemical, mineralogical, and isotopic composition of wide-spread shallow groundwaters in the MDV and soils associated with these features. To complement our field work, we are developing and applying a novel thermal-reactive-transport model using data collected from the field to constrain the model inputs and ground-truth the model outputs. At the conclusion of our research, we will have rigorously tested if mechanisms of groundwater formation in the MDV can produce wide-spread shallow groundwaters on Mars, and what the properties of putative Martian groundwaters would be.

A key goal of this project is to explain the formation of Recurring Slope Lineae (RSL) on Mars:

• Dark, narrow lineations on sunward facing slopes.
• Lengthen downslope during the Martian spring, and then fade during the autumn and winter.
• Reappear annually.

RSL are most likely caused by flowing liquid water. If true, then Mars is the only other solar system body, outside of Earth, where liquid water has been observed flowing on the surface. To understand how RSL form on Mars, and what their chemical composition is, we are investigating how similar features in the MDV form during the 2017/2018 Antarctic field season.

The MDVs are extremely cold and dry, and are the best analog we have on Earth for conditions on Mars. So by studying surface processes in the MDV, we can better understand what could be happening on Mars. A key target for our investigation in the MDVs is Don Juan Pond, the saltiest body of water on Earth. The unusual chemistry of Don Juan Pond causes it to spontaneously suck water from the atmosphere and prevents the pond from freezing until below -50°C. RSL-like features also form above Don Juan Pond.

Past Projects

Salts and Soils on Mars: Analysis of Phoenix Aqueous Chemistry in the Context of Previous Lander Data

Catling, D. C.; Light, B.; Giles, M.; Toner, J. D. (postdoc)

Abstract: Key issues for Mars exploration concern the origin of aqueous alteration materials and what they mean for the evolution and habitability of Mars. We propose to use data analysis and modeling to constrain the salt chemistry of the soil measured by Phoenix in the context of soil chemistry measured by the Viking Landers (VLs), Mars Pathfinder (MPF) and the two Mars Exploration Rovers (MERs). The major questions we seek to address are: (1) What is the quantitative composition of salts at the Phoenix site? (2) Is this consistent with the composition of soils at other lander sites? (3) What does the composition of salts indicate about the origin of the soil? (4) Assuming Phoenix soils went through past aqueous processing and evaporation or freezing, what salts would be expected, what is their chemical and physical expression, and can we identify these in lander data?

Key results from this project include :

• The salt chemistry of Mars: We reanalyzed and revised data from Wet Chemistry Laboratory (WCL) experiment on the Mars Phoenix Lander. The WCL experiment measured the salt composition of Martian soils by adding water and analyzing what salts dissolved into solution using an array of sensors. Our analysis provides better estimates of the measured solution composition, as well as improved uncertainty estimates.
• Supercool solutions: Salt solutions on Mars will supercool i.e. cool as a liquid to below the point where theoretical models predict they should freeze solid. For perchlorate salts believed to be on Mars, supercooling is extreme. These salts will cool down to -120°C, at which point they form a glass-like substance. This would greatly extend the possible condition for liquid water on Mars. In addition, glasses preserve organics in a pristine state and life can survive in the glass state.