Science Mail Online
All the latest UK and international science and technology news, video and pictures from the Daily Mail and Mail on Sunday // via fulltextrssfeed.comLife on Mars: Spacecraft finds life may have existed on Mars billions of years ago Jul 19th 2013, 09:14
* CURIOSITY ROVER FOUND MARS'S ATMOSPHERE WAS ONCE THICKER AND WETTER
* It is believed to have contained oxygen long before Earth's atmosphere did
* YET NO METHANE WAS FOUND, WHICH WOULD HAVE SUGGESTED LIFE'S STILL THERE
* AMOUNT OF METHANE WAS DETECTED BY EARTH-BASED TELESCOPES IN 2009
* But latest negative results from craft cast doubt on present-day life
By Mark Duell
PUBLISHED: 01:08 EST, 19 July 2013 UPDATED: 04:14 EST, 19 July 2013
The chances of life existing on Mars at some point billions of years ago were today dramatically boosted after a spacecraft found its atmosphere was once thicker, warmer and wetter.
The Red Planet is believed to have had an oxygen-rich atmosphere long before Earth and this suggests it could have once harboured alien lifeforms.
Yet the Curiosity rover - the most advanced spacecraft to ever land on the red planet - did not find any methane, which has disappointed those who believe microbes may still linger there.
Craft: This shows a self-portrait taken by the NASA rover Curiosity in Gale Crater on Mars. Measurements of the Martian air by the rover found it is mostly made of carbon dioxide with traces of other gases
Theory: There was interest in what may have existed in the past on Mars, after Curiosity found that much of the planet's atmosphere has been lost over time, suggesting it was once warmer
They had their hopes up after telescopes on Earth had detected a surprising and mysterious amount of methane in 2009 in three regions in the Martian western hemisphere.
On Earth, methane is mainly a by-product of life - from animal digestion and decaying plants - and the gas can also be produced by non-biological processes.
But last year, the Curiosity team reported no definitive whiff of methane near the landing site, and since then, the rover has taken several more air samples.
There are also plans to sniff the atmosphere during a drive to the Mount Sharp mountain. And in the autumn NASA is set to launch a Mars-orbiting spacecraft aimed at solving the methane mystery.
Called Maven, the craft will target the Martian atmosphere. Scientists want to know if it actually exists, determine the abundance and whether that varies by year or location.
Disappointment: Last year, the Curiosity team reported no definitive whiff of methane near the landing site, and since then, the rover has taken several more air samples
Red planet: A view of Mars that was stitched together by images taken by NASA's Viking Orbiter spacecraft
'The fact that it's turned out to be pretty much disproven - it's not a surprise, but a disappointment perhaps,' planetary scientist Adrian Brown of the SETI Institute in California, told Wired magazine.
'The fact that (life today) has turned out to be pretty much disproven - it's not a surprise, but a disappointment perhaps'
Adrian Brown, planetary scientist
The Curiosity found the air is made mostly of carbon dioxide. This closely matched what the twin Viking landers detected in the late 1970s and what scientists have gleaned from Martian meteorites.
And there was also interest in what may have existed in the past on Mars, after Curiosity found that much of the planet's atmosphere has been lost over time, suggesting it was once warmer.
This would have been more conducive to liquid water flowing on the surface - and potentially even life existing on the planet, reported Wired.
Mars' atmosphere is overwhelmingly dominated by carbon dioxide, unlike Earth's air, which is a mix of nitrogen and oxygen. However, there was still a small surprise.
Results: The nuclear-powered, six-wheel rover set down in an ancient crater near the Martian equator almost a year ago
Viking found nitrogen to be the second most abundant gas in the Martian air, but Curiosity's measurements revealed a nearly equal abundance of nitrogen and argon, a stable noble gas.
Mission scientists are puzzled, but suspect it might have to do with the different tools used to sample the atmosphere.
'It's more or less an interesting observation' but doesn't change the notion that Mars lost most of its original atmosphere to space, transforming the planet into a cold desert, said Paul Mahaffy of NASA's Goddard Space Flight Center, who is in charge of Curiosity's air sampling experiments.
The nuclear-powered, six-wheel rover set down in an ancient crater near the Martian equator almost a year ago. The measurements were detailed in two studies appearing in the journal Science.
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