It is not the first time Nasa's robot has detected methane levels on the planet, and scientists are still not sure whether the gas is caused by living microbes, because geothermal reactions, with no biological life, can also create methane.
The unexpected discovery has led scientists to scrap previously made rover plans in favor of running 'a follow-up experiment, ' according to an email written by mission project scientist Ashwin R. Vasavada, which was obtained by the newspaper.
NASA has not yet made any announcements about the Curiosity's methane findings. The results of these observations are expected back on the ground on Monday.
However NASA's pioneering Viking landers in the 1970s revealed a desolate landscape on the Red Planet.
Humanity have always been intrigued by the possibility of alien life on Mars.
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.
Scientists were undeterred in their search for methane on Mars, though. The European Space Agency's ExoMars Trace Gas Orbiter, with the ability to detect 50 parts of methane per trillion by volume in the Martian atmosphere, has been collecting data for a little over a year, and has so far come up completely empty handed.
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.
But it's also possible that the gas was produced millions of years ago by now-extinct life, the outlet reported. However, those findings were at the edge of the detection power of these tools, and many researchers thought the methane might just be a mirage of mistaken data.
When Curiosity landed on Mars in 2012 it found barely any traces of methane, with less than one part per billion in the atmosphere. It seems that the rise and fall of methane gas is seasonal but the scientists at NASA do not have enough information on the reason yet. A new analysis of old Mars Express readings confirmed Curiosity's 2013 findings.
The Curiosity team has detected methane many times over the course of the mission, also noting there has been sudden spikes in the past.
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 previous year. The newest measurements are 21 parts per billion.
Good science relies on follow-up and repeat findings before confirmation, so while it's easy to get excited by the potential for signs of life, a lot more work needs to be done before we can truly confirm the presence of any tiny, underground martian friends.