IN-SITU METEORITE STUDY ON MARS — ABUNDANCE AND USEFULNESS AS MARTIAN SYSTEM RESEARCH TOOLS, WITH STRATEGIC RECOMMENDATIONS FOR ONGOING AND FUTURE ROVING MISSIONS

After over 73 kilometers of cumulative odometry, the Spirit, Opportunity, and Curiosity rover science teams have identified more than 45 rocks of confirmed or candidate exogenic origin (meteorites) on Mars. Far from being unrelated to Mars science, these materials are highly useful for addressing a variety of Mars-specific science questions and mission objectives. Studies so far include 1) chemical and physical weathering processes with associated implications for mineral-water interactions, paleo-wind direction, and ripple migration during the Amazonian period; 2) timing of chemical weathering rates; 3) impact processes; 4) atmospheric density models; 5) atmospheric fragmentation and production of strewn fields; and 6) thermal infrared behavior of dust on reflective metal surfaces. Additional science not related to Mars is approachable through taxonomic and other studies.

As on Earth, statistical re-evaluation of the meteorite inventory is enabled with each new find. Survivability bias in the martian environment appears to favor irons over chondrites, for example, and speaks volumes about selective fragmentation of chondrites over time by mineral-water interaction – similar to what is observed in Mars-analog environments on Earth. However, meteorite measurements and photo-reconnaissance conducted thus far have often been performed in something of an ad-hoc manner, owing to the serendipitous nature of each find, which is nearly always off-nominal to campaign objectives at the time of discovery. This has resulted understandably in measurement inconsistencies, which introduce challenges to serious studies. A more formal and concerted effort is warranted for this discipline as new finds are encountered. We can reliably anticipate meteorite finds to be part of ongoing roving science not only for Curiosity, but also for the Mars 2020 and ExoMars rovers scheduled for launch next year. The applicable instrument suites for these spacecraft will encompass X-ray fluorescence, ultraviolet, visible to infrared, and laser Raman spectrometers, a wide variety of imagers, and organic molecule analyzers. Analytical programs including the best synthesis of each measurement type should be outlined and discussed during strategic planning as contingencies for when these valuable rocks are encountered.