Radiolytic H₂ Production in Martian Environments

Area of Science:

• Astrobiology and Planetary Science
• Geochemistry and Radiochemistry

Background:

• Microbial life on Mars may be supported by hydrogen (H2) produced via water radiolysis.
• Understanding radiolytic H2 production is crucial for assessing Martian habitability.

Purpose of the Study:

• To quantitatively assess the potential magnitude of radiolytic H2 production in ancient and present Martian wet environments.
• To evaluate H2 production rates at proposed Mars 2020 landing sites and extreme H2-producing locations.

Main Methods:

• Quantitative assessment based on radionuclide compositions of Martian surface and subsurface environments.
• Calculations performed for eight proposed Mars 2020 landing sites and three extreme H2-producing sites.
• Comparison of calculated rates with terrestrial environments harboring microbial life, such as subseafloor basalt.

Main Results:

• Radiolytic H2 production rates vary by a factor of ~1.6 across proposed landing sites and ~6 across extreme sites.
• Rates in wet Martian sediment and microfractured rock are comparable to terrestrial environments with low microbial concentrations.
• H2 production rates in low-porosity Martian sediment exceed those in South Pacific subseafloor basalt; rates in high-porosity sediment and microfractured rock are similar.

Conclusions:

• Radiolytic H2 production in certain Martian environments is sufficient to potentially support microbial ecosystems.
• Martian H2 yields can exceed calculated rates if minerals or brines amplify production.
• Further investigation into Martian subsurface conditions and mineralogy is warranted to fully assess habitability.