Mars researchers report that NASA’s Curiosity rover detected long chain alkanes at roughly 30 to 50 parts per billion in the Cumberland mudstone in Gale crater, and scientists proposed those alkanes formed during analysis by the rover’s Sample Analysis at Mars instrument.
Dr. Alexander Pavlov of NASA’s Goddard Space Flight Center and colleagues argue the measured values are a lower limit, because ionizing radiation likely destroyed most original organics during tens of millions of years of surface exposure, the team wrote in Astrobiology.
The authors combined laboratory radiation experiments, mathematical modeling, and Curiosity data to “rewind the clock” about 80 million years of exposure, allowing them to estimate that the mudstone originally contained between 120 and 7,700 parts per million of long chain alkanes or their fatty acid precursors.
They assessed known abiotic sources and found them inadequate, noting delivery by meteorites and interplanetary dust particles falls short by many orders of magnitude given sedimentation rates and the inability of dust to penetrate lithified rock.
The team also judged atmospheric haze deposition unlikely because early Mars probably lacked methane rich conditions needed for substantial haze, and hydrothermal synthesis seems inconsistent with the Cumberland mudstone mineralogy, they said.
The researchers acknowledged that extraordinary claims require extraordinary evidence and that multiple lines of proof are necessary, yet they concluded it is not unreasonable to hypothesize an ancient Martian biosphere could produce the inferred organic enrichment, with possible contributions from allochthonous hydrothermal organics.
Regional Storm Linked To High Altitude Moisture And Hydrogen Escape
During a normally quiet northern summer, a short lived regional dust storm lifted large amounts of water vapor into the middle and upper atmosphere, and Shohei Aoki at Tohoku University documented a sharp rise in high altitude water tied directly to that storm.
Observers describe the mechanism as dust absorbing sunlight and rapidly heating the middle atmosphere, raising the temperature at which clouds form and leaving more vapor aloft where winds carried it upward.
Measurements showed water vapor above 25 miles, or 40 kilometers, reached up to ten times the usual amount for northern summer, and hydrogen near the top of the atmosphere rose to about 2.5 times previous seasonal peaks, the Emirates Mars Mission and other instruments recorded.
Europe’s Trace Gas Orbiter tracked the vapor by analyzing sunlight, Mars Reconnaissance Orbiter provided weather maps and temperature profiles, and the Emirates Mars Mission monitored hydrogen, allowing teams to cross check each step of the process.
Researchers said the event shows short, intense regional storms can drive bursts of hydrogen escape and that such episodes deserve more attention in models estimating long term Martian water loss, particularly if ancient Mars produced similar disturbances more often.
