There’s growing buzz about data gleaned by NASA’s Curiosity rover on Mars, specifically over the issue of methane detection on the Red Planet.
On one hand, methane can be geological in origin. But then there’s the prospect that the gas is biotic, or caused by living organisms — meaning it could be the gaseous residue of long-extinct microbes or even the output of Martian organisms alive and well today.
The main instrument for the rover’s astrobiology research is the gold-plated Sample Analysis on Mars (SAM), which includes three complex lab tools and is the largest and heaviest (at 88 pounds, or 40 kilograms) on Curiosity. Many of its capabilities are brand-new or significant improvements on the Viking instruments. [5 Bold Claims of Alien Life]
The principal investigator for SAM is Paul Mahaffy of the Goddard Spaceflight Center, who has worked to put together the instrument for more than eight years. He and other NASA scientists are quick to explain that finding organics on Mars will be very hard to do, and that it’s difficult to find organic carbon in rock samples even on Earth. But he sees some real opportunities.
Recent evidence, however, emphasizes that the methane really is there. The Thermal Emission Spectrometer on the Mars Global Surveyor, an orbiting satellite that collected data from 1996 until 2006, detected relatively high levels of methane in Mars’ atmosphere. MGS revealed that Mars’ methane levels vary by location and season: they are highest in summer and autumn, in regions with volcanoes or other geothermal activity. Chris McKay, a Mars specialist at NASA, told SPACE.com, ”Methane on Mars should have a lifetime of 300 years and should not be variable. If it is variable, this is very hard to explain with present theory. It requires unexpected sources and unexpected sinks.”
This makes it sound like the methane is produced by geology, not biology, but scientists are skeptical that geological processes can account for the quantity and variability of methane found. “Methane is really quite a rare gas in hydrothermal/volcanic exhalations,” Dirk Schulze-Makuch, an astrobiologist at Washington State University, said in an interview with SPACE.com.
“Based on evidence, what we do have is, unequivocally, the conditions
for the emergence of life were present on Mars — period, end of story,”
said Michael J. Mumma, a senior scientist for NASA at the Goddard Space
Flight Center in Greenbelt, Md., who led one of three teams that have
made still-controversial claims of detecting methane in Mars’s
atmosphere. “So life certainly could have arisen there.”