On Tuesday, NASA scientists announced the discovery of methane and complex organic compounds on Mars, a possible sign of current or previous life on the planet. The findings, announced at the American Geophysical Fall Meeting and published in the journal, Science, used data from drill samples taken from a rock called Cumberland, as well as erratic levels of atmospheric methane collected by the rover, Curiosity.
Since the rover’s landing, NASA scientists have been regularly recording the Martian atmospheric chemical content using the Sample Analysis at Mars (SAM), one of two laboratory instruments imbedded in the rover. What researchers found were generally low levels of atmospheric methane at 0.9 parts per million (ppm) and occasional, radical spikes averaging 7 ppm over a 20-month period, reports Universe Today. The methane spikes suggest natural production of the gas on the planet, though scientists are not yet sure where or how the methane is being produced, or if the source is biological or geochemical.
The rover recorded four spikes in total, lasting a few weeks each, concentrated over a relatively small area,roughly 2,565 square feet, leading researchers to believe that the gas may be expelled through a vent on the surface. While NASA remains open to the possibility that the source is biological—which would prove life on Mars—there are multiple causes of methane gas production that do not point to life, including interactions between rock and hot water or meteorite debris burning up in the sunlight on the planet’s surface. Further tests of the atmospheric methane could help to determine the source of the gas, though it is unclear when or even if further studies will be conducted, reports The Scientific American.
NASA’s recent findings come as a surprise to the scientific community, especially in the wake of measurements released only a year ago by Curiosity’s team, which showed virtually nonexistent levels of methane gas in the Martian air. NASA scientists employed increasingly focused efforts the following year in the search for signs of alien life, collecting samples over a longer period of time and studying samples that have been “enriched” to remove carbon dioxide and reveal even trace amounts of methane. The increased efforts worked and offered the scientists a more complete view of the chemical composition of the surface air, showing the background levels of methane at just under one part per million, a measurement too low for the rover’s standard operating instruments to detect.
The spiked levels of methane detected on Mars present many more questions than answers. According to previous estimates, methane released on the planet’s surface should remain in its atmosphere for about 300 years, but the spikes recorded by NASA disappeared within weeks. Using spacecraft measurements and telescopes, scientists estimated the amount of background methane on the planet, but data from the rover showed the gas’ levels were half what scientists were expecting. The planet’s volcanoes have also been dead for millions of years, making many question the viability of a geochemical source of methane and supporting the possibility of a biological origin.
In a separate discovery, NASA’s Curiosity team found organic compounds more complex than methane after drilling into rocks in search of clues. Testing of samples from the planet’s surface yielded no organic compounds, so the rover team began drilling into rocks to extract samples, eventually coming upon the Cumberland rock, which contained unknown organic compounds. The researchers also found perchlorate, an active chemical capable of breaking compounds down into less complex forms, leaving researchers at NASA even more perplexed.
By Sree Aatmaa Khalsa
Photo by NASA/JPL-Caltech/MSSS – Flickr License