For over a century, science fiction authors have imagined that humanities’ first contact with extraterrestrial life would come via intelligent humanoid aliens arriving on Earth in technologically advanced spaceships, likely in pursuit of interstellar conquest. If the latest Red Planet news from NASA turns out to be that first contact, the reality is far more mundane than the fiction. There may be Martians, but if so, we’ve only seen their gas, not their ships. Even calling it “their” gas may be getting ahead of ourselves.
Over the weekend, NASA’s Science Mission Directorate announced that the Mars Curiosity Rover has detected an increase in the methane gas concentration of the Red Planet’s atmosphere at its position. This marks the third such surge of methane observed by Curiosity, confirming its earlier observations and adding intrigue to the notion that the methane could be biological in origin.
But the default setting of scientists is skepticism. Measurements have to be defended. If there’s any reasonable doubt, then the results are not fully accepted. Indeed, the general philosophy in science is that even well-established, observed truths are only true to the extent that they have been tested. Not only were the first detections of methane in Mars’ atmosphere — 15 years ago, by an orbiter and Earth-based telescopes — not considered to be a detection of extraterrestrial life, they weren’t even accepted as a detection of methane!
Now that the search for life is heating up, what should we expect?
But then six years ago, in 2013, only one year into its mission, the Curiosity Rover began routinely measuring methane concentrations from the Martian surface. For the first eight months of its mission, it found a very low methane background level of less than one part per billion, or 1ppb.
Curiosity’s first detection of a methane spike occurred at Gale crater in June 2013 when it measured 6ppb. The next day, on June 16, 2013 the orbiting Mars Express Explorer measured 15ppb above Curiosity’s location in Gale crater. Six months later, Curiosity again detected increased…