NASA has proposed sending both an orbiter and a robotic explorer to Mars in the next decade to follow up on the recent report that Mars “hotspots” emit plumes of methane gas, which could be produced by either geothermal reactions or by deeply buried bacteria that breathe out methane as a waste product. That exciting phenomenon, which is still being debated by Mars experts, was observed by researchers using ground-based telescopes to measure seasonal fluctuations of gases on the planet. Researchers say closer observations would have a much better chance of determining whether the methane does signal the ultimate prize: extraterrestrial life.
NASA officials sketched out their proposal at a meeting of Mars scientists, but stressed that plans could change. The current idea is to launch the Mars Science Orbiter in 2016 followed by a exobiology lander or rover mission launched during a particularly juicy launch window in 2018 (the best since the Spirit and Opportunity rovers)…. The plan would also follow a natural progression: MSO would map the methane; the lander or rover would go after it with a suite of astrobiological instruments [Nature blog].
Researchers say an orbiter would certainly be able to confirm or deny the earlier report of methane hotspots by mapping methane emissions, and that the orbiter could also probe the composition of the gas. The case for a biological origin for the gas would be strengthened if there is an overabundance of methane laden with the isotope carbon-12, which life prefers to process over heavier isotopes. If, however, the atmosphere also contains heavier hydrocarbons such as ethane, which life as we know it cannot produce, that would point to a geological source for the methane [New Scientist].
The new plan for an orbiter in 2016 with a rover or lander to follow later came about due to some budget issues. The agency originally aimed to launch a lander or rover in 2016, but the plans will be dropped in order to pay for a two-year delay in the launch of the hulking Mars Science Laboratory rover that will cost NASA an estimated $400 million [New Scientist]. By sending an orbiter in 2016 instead of a rover, NASA will also ensure that a communications orbiter will be in place for future lander missions; the current orbiters, Odyssey and Mars Reconnaissance Orbiter, will be getting old.
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