Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters, in Washington, said: "With these new findings, Mars is telling us to stay the course and keep searching for evidence of life".
"The new findings - "tough" organic molecules in three-billion-year-old sedimentary rocks near the surface, as well as seasonal variations in the levels of methane in the atmosphere - appear in the June 8 edition of the journal Science", NASA reports in a news release recapping the Thursday, June 7 press conference.
The Mars 2020 rover will scan the Red Planet for signs of ancient life by studying terrain that once consisted of flowing rivers and lakes more than 3.5 billion years ago.
The rover also found seasonal fluctuations of atmospheric methane. At a few dozen parts per million, the detected levels are 100 times higher than previous finds, but scientists still can not say whether they have origins in biology or geology. Curiosity Rover's Twitter featured a cheeky call asking followers to tune it to see its findings. "It tells us that this ancient environment on Mars could have supported life", Eigenbrode said. The rover's Sample Analysis at Mars (SAM) instrument cooked some of the Martian dirt and unlocked some long-hidden carbon-containing molecules, some with sulfur and others with relatively complex structure.
Both the methane gas and soil compounds are organic matter. But they aren't proof of life on Mars, or even necessarily strong evidence that there's anything living, or anything that used to be alive, out there.
"These clathrates lock the methane inside a water-ice crystal structure and are incredibly stable for millions of years until environmental conditions change and suddenly they can release that gas", says Duffy.More news: TERROR PLOT FOILED: Israel Thwarts NETANYAHU ASSASSINATION Attempt
More news: Amazon Fire TV Cube combines Amazon Echo & Fire TV into one device
More news: Chemotherapy can be avoided with common breast cancer
While it could be produced by microorganisms under the surface of Mars, it could also be produced by non-biological processes such as chemical reactions in rocks, or the breakdown of organic matter in dust delivered by comets or meteors, by UV radiation. This mudstone gradually formed billions of years ago from silt that accumulated at the bottom of the ancient lake.
Scientists hope to further the search for signs of life on Mars with the European and Russian rover, ExoMars, scheduled to land in 2021.
NASA's Jennifer Eigenbrode said in an interview this year, 'I look at organic molecules in rocks, ice and sediments and try to figure out where they came from and what happened to them over time. "The first one would be life, which we don't know about". And now they've added a catalogue of organic molecules to that list.
The other set of results announced today deals with the mysterious case of Mars's methane. Seasonal peaks were detected in late summer in the northern hemisphere and late winter in the southern hemisphere.
They may have also have been carried to Mars on an asteroid, for instance.
"The wonderful consistency of the results makes me think we have a slam-dunk signal for organics on Mars". On Mars, where we only have a few molecules from a remote probe, this stuff is light years away from being conclusive.
"[Curiosity's] molecular observations do not clearly reveal the source of the organic matter in [Gale Crater]".