The report shows that the new measurements arrived late last week yet NASA is still to announce the findings.
It is also possible that the methane is ancient, trapped inside Mars for millions of years but escaping intermittently through cracks.
"Given this surprising result, we've reorganized the weekend to run a follow-up experiment", project scientist Ashwni R. Vasavada said in an internal email obtained by the outlet.
NASA's Curiosity Mars rover has detected a huge spike in Methane, generating excitement among scientists.
The robot frequently "sniffs" the Red Planet for the gas but has never before seen so high a concentration - of 21 parts per billion (ppb).
But the orbital ESA/Roscosmos Trace Gas Orbiter (TGO) mission, now in Martian orbit, found no traces of methane in the atmosphere, adding to the mystery.
Through the course of its mission, Curiosity has noticed a number of spikes in methane, and it senses a background level that appears to have a seasonal pattern to it. The new discovery of an abundance of methane gas has once again brought it in the spotlight.
Results from the additional experiment should be beamed-back and analysed today.
The methane gas discovery is said to be exciting to scientists because it it could indicate that there are microbes living on Mars - possibly the descendants of life that migrated underground when it was speculated that Mars was a warmer, wetter and more hospitable environment four billion years ago.
NASA said it will be working with other researchers including the European Space Agency's Trace Gas Orbiter team, which has not detected any methane in just over a year of orbiting Mars. It's a particularly riveting discovery because the methane levels discovered by the rover are about three times higher than previous detections, leading to some speculation the gas may be biological in origin.
But although the robot's big onboard chemistry lab - the Sample Analysis at Mars (SAM) instrument - can detect the gas's presence, it can say nothing about the source.
The rover has been sniffing around Mars since landing in 2012.
Methane is an important molecule for microbes on Earth and its detection on another planet has led to speculation that microscopic alien microbes could be excreting the compound at significant enough rates for NASA to detect.