Generally, methane presence on Mars has a global average of 10 ppbv, so NASA is conducting follow-up observations to see if it can find where the unusually high concentration has come from.
The results of this weekend's experiments are expected to be sent back to Earth on Monday.
However NASA's pioneering Viking landers in the 1970s revealed a desolate landscape on the Red Planet.
So whatever methane there is on Mars could only exist very briefly on the surface before dissipating into the atmosphere. Now, they are entertaining the notion that if life ever did arise on Mars, its microbial descendants could have migrated underground and persisted.
The detection of methane would be a major discovery because, as the Times noted, it breaks down within a few centuries due to sunlight and chemical reactions-meaning it would have had to have been generated quite recently in historical terms.
Methane gas is usually a byproduct of microbes called methanogens which survive in rocks found deep underground in Earth and even in digestive tracts of animals.
NASA has detected methane over the course of the mission.
Volcanoes produce a lot of methane and while there is no active volcano on Mars, it is possible it was trapped inside the ground and is being released slowly.
However, those findings were at the edge of these tools' detection power, and some researchers suspected the methane readings could have just been an illusion of mistaken data.
When NASA's Curiosity arrived in 2012, it was able to record methane gas that measured one part per billion in the atmosphere - too little to be significant. It's not an entirely enormous amount by earth standards, only "21 parts per billion units by volume" or ppbv. The team expects the new reading to arrive early this week.
But the Trace Gas Orbiter, a newer European spacecraft launched in 2016 with more sensitive instruments, did not detect any methane at all in its first batch of scientific observations past year. He confirmed he had been told of the reading of 21 parts per billion but added that the finding was preliminary.
Marco Giuranna, a scientist at the National Institute for Astrophysics in Italy, who leads the Mars Express orbiter's methane measurements, said scientists on the Curiosity, Mars Express and Trace Gas Orbiter missions had been discussing the latest findings.
They've also been in contact with the Trace Gas Orbiter team at the ESA to see if an atmospheric detection was made at the same time.
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