A NASA robot has found more building blocks for life on Mars, the most complex organic matter yet from 3.5 billion-year-old rocks on the surface of the red planet, the USA space agency said on Thursday.
The Curiosity rover, which has travelled 19.3 km since it landed in the Gale crater almost six years ago, detected a number of organic molecules in pieces of Martian mudstone it drilled from the lake bed and heated in its oven.
Nasa's Curiosity rover has discovered organic matter on Mars, the agency has announced in a press conference. NASA also announced it had found signs of "seasonal methane" in the Mars atmosphere.
"We found organic molecules in rocks from an ancient lakebed", said Jen Eigenbrode, a research scientist and astrobiologist at NASA's Goddard Space Flight Center in Greenbelt, Md.
The samples were drilled from the base of Mount Sharp, inside a basin called Gale Crater.
That may be because numerous compounds, such as thiophene, methanethiol and dimethyl sulfide, had sulfur atoms in their molecular structure - which would strengthen the relatively fragile organic molecules, allowing them to survive the radiation bombarding the planet's surface for so long.
More powerful spacecraft are needed to prove whether life ever existed on Mars.
A seasonal change in methane levels is exciting, he said, because 95 percent of the methane observed on Earth is the result of biology. The molecules could have been deposited on Mars by meteorites or formed in the lake through non-biological means.
Questions remain, however, as to how the organic material was formed. "While we don't know the source of the material, the wonderful consistency of the results makes me think we have a slam-dunk signal for organics on Mars", Eigenbrode said. If researchers saw this signature on Mars, the case for life would get stronger. The rock samples were analyzed by SAM, which uses an oven to heat the samples (in excess of 900 degrees Fahrenheit, or 500 degrees Celsius) to release organic molecules from the powdered rock. "We can find organic matter preserved in mudstones that are more than three billion years old", Siebach said.
"Organic molecules serve as the building blocks of life while most of the methane in Earth's atmospheric comes from animal and plant life, scientists explained". Much as a detective figures out whodunnit by filling in all the details of a crime first, astrobiologists set about piecing together a picture of the Martian environment to figure out if the planet could even support life, now or in the past. It has been tacking across the floor of Gale Crater on Mars for five years, returning stunning images of Martian landscapes, with vistas opening up to show rocky outcrops seamed with mineral veins. A likely candidate: "serpentinization", where water and minerals react, releasing methane.
The agency and the paper's authors said these new finds suggest we need to keep looking, rather than representing a smoking gun.
"We can not rule out its creation from biological activity ..."