Over the last decade, there have been many reports of methane in the Martian atmosphere detected by Earth-based telescopes and satellite observations.
The presence of methane, the main component of natural gas on Earth, would be a sign that the planet is still alive — microbes living far below the Martian surface could potentially be releasing the gas.
But new measurements from the Curiosity rover show that the current Martian atmosphere contains very little or no methane, greatly reducing the likelihood that methane is being produced by bacteria under the surface of Mars.
The discovery also limits the probability that a significant amount of methane was brought to Mars from external sources, like meteorites and dust from other planets.
“Because methane production is a possible signature of biological activity, our result is disappointing for many,” study author Christopher Webster, director of the microdevices lab at NASA’s Jet Propulsion Laboratory, told Business Insider.
The team used Curiosity’s Tunable Laser Spectrometer to measure the amount of methane on Mars. The device shoots laser beams through a chamber as Martian air is pumped into the same part of the instrument. Methane is detected by observing how the light from these lasers is absorbed by the Martian air. Researchers can pick up the distinct absorption lines created by molecules of methane.
Based on the data, the researchers estimate that the most methane that could currently exist in the Martian atmosphere is 1.3 parts-per-billion, which is much lower than previous estimates ranging from 5 to 10 parts-per-billion.
The finding does not rule out the existence of microbes that emit gases other than methane, says Webster. And there is still a possibility that methane-producing organisms lived on Mars in the past but died out.
“Curiosity is not a life-detection mission, but is there to assess the habitability of the Red Planet, and the excitement from the many important observations from its payload eclipse any disappointment in the methane result,” said Webster. “The Curiosity rover will continue to make its measurements of both atmosphere and rock samples to discover if organics other than methane exist on Mars.”
The findings were reported in the journal Science Thursday, Sept. 19.
NOW WATCH: Briefing videos
Business Insider Emails & Alerts
Site highlights each day to your inbox.