Constraining the Potential Liquid Water Environment at Gale Crater, Mars.

Area of Science:

• Planetary Science
• Astrobiology
• Geochemistry

Background:

• The Mars Science Laboratory (MSL) Rover Environmental Monitoring Station (REMS) collects meteorological data at Gale crater.
• Understanding the potential for liquid water on Mars is crucial for astrobiology and habitability assessments.
• Relative humidity and ground temperature data are key to constraining brine stability.

Purpose of the Study:

• To investigate the potential for surface and subsurface liquid brine formation on Mars.
• To analyze REMS data using updated calibrations and consistent relative humidity comparisons.
• To assess the role of calcium perchlorate deliquescence in brine formation.

Main Methods:

• Utilized updated calibrations for REMS temperature and relative humidity data.
• Performed consistent relative humidity comparisons (with respect to liquid vs. ice).
• Modeled shallow subsurface environments and analyzed terrain thermal inertia and albedo.

Main Results:

• Surface brine formation is unlikely in the first 1648 sols, with only two instances meeting favorable conditions.
• Shallow subsurface environments, particularly those with low thermal inertia (Γ ≲ 300 J m⁻² K⁻¹ s⁻¹/²), may occasionally support brine formation.
• Terrains with Γ ≲ 175 J m⁻² K⁻¹ s⁻¹/² and albedos ≳0.25 are most conducive to subsurface brine formation around Ls 100°.

Conclusions:

• While surface brines are not favored, shallow subsurface brines are possible under specific conditions.
• Formed brines would not meet criteria for potentially habitable environments.
• This study refines our understanding of water activity and habitability potential on Mars.