Since John Grotzinger, one of the leaders of NASA’s Mars exploration program, speaking about Mars Curiosity rover’s findings, had said in mid-November, “This data is gonna be one for the history books. It's looking really good," (as earlier reported in Digital Journal
), scientists and astronomers had been speculating that NASA might be about to announce the discovery of extraterrestrial life .
An announcement by NASA
at the fall meeting of the American Geophysical Union
(AGU) being held in San Francisco this week makes it clear that no definitive evidence of life on Mars has yet been found although Curiosity’s analyses are, nonetheless, exceeding all expectations.
In the statement released at the AGU, NASA’s Michael Meyer, program scientist for Curiosity said, “These results are an unprecedented look at the chemical diversity in the area,” before going on to say there is “no definitive evidence for any organics that must come from Mars at this point in the mission.”
Curiosity project scientist John Grotzinger, whose November comments had given rise to speculation of a momentous discovery, said at the AGU briefing, “Even though this instrument detected organic compounds, first of all we have to demonstrate that they are indigenous to Mars.”
Grotzinger said the reactions to his earlier comments made to National Public Radio (NPR)
had surprised him and emphasised the painstaking nature of research undertaken by the Mars Curiosity team, saying, “We’re doing science at the speed of science.”
He acknowledged that his comments on NPR had raised expectations of Curiosity having made a dramatic discovery but his earlier comments have also highlighted just how much the Curiosity mission has caught the imagination, not just astronomers but a much wider audience,
“the first thing I thought was, ‘Gosh, I have to be careful about what I say.’ The great thing about it is, as the days went by and I thought about it further, my reaction was, ‘I think it’s terrific that this mission has such wide appeal and public interest.’” He went on, “And the mission has delivered an unbelievable wealth of data. We’ve had over 11,000 images returned that the public has enjoyed. We’ve had over 2.5 million observations by the weather station. I could go on and on. It’s just been spectacular.”
But Grotzinger cautioned that Curiosity’s middle name is “patience” and that the public need that in abundance. “What this mission is about is integrative science,” he said. “There’s not going be one single moment where we all stand up and on the basis of a single measurement have a hallelujah moment.” He referred to Curiosity being “a car that comes with a 10,000 page user manual that we also have to write as we read it. That’s where the patience comes in.”
Whilst one of Curiosity’s principal objectives is to determine if Mars could have supported microbial life in the past, some of the discoveries made since it landed at Gale Crater on the Red Planet on August 6 last have been highly significant, not least the discovery of an ancient riverbed close to the landing site. Said Meyer, “We actually picked the right place for the rover to land.”
Within Gale Crater, Curiosity made its way to a wind drift now known as Rocknest where five soil scoops were collected for analysis. Most of the scoop material is a fine, dry sand with a grain size about half that of an artificial sweetener pill. The drift is not thought to be active since the fine sand was encrusted with coarse grains and a layer of dust. Soil samples typical of Martian soils were deliberately sought by the Curiosity team. As Grotzinger put it, “We had to do a lot of work to make sure that this was something that was a garden variety of Martian soil. We didn’t want something that was adventurous.”
Soil samples were heated up using the SAM (Sample Analysis at Mars)
instrument and the gases released analysed. Among gases identified were oxygen and chlorinated methane compounds, the latter being a carbon based compound. The research team consider the oxygen and chlorine detected probably emanate from perchlorate which has previously been detected on the Martian surface.
The team are certain the chlorine was of Martian origin but in order to confirm the carbon, similarly, originates on Mars, rigorous analysis is still needed before the possibility of the Curiosity mission itself being the source of the carbon can definitely be ruled out. This will be done by means of control experiments comparing the Martian sample with test samples brought by Curiosity from Earth.
If and when NASA determines the carbon is of Martian origin then isotope ratio analysis is likely to be used to help ascertain if the carbon-based compounds could have originated from ancient Martian biological processes. This type of soil analysis would be the first time such an experiment had been carried out on Mars.
Curiosity rover is now at a location called Point Lake. The next task is to find a drilling site with the Curiosity team hoping to commence drilling by the end of 2012. After that, Curiosity is likely to head towards Mount Sharp.
Putting the mission in the context of other recent advances, John Grunsfeld, NASA associate administrator for science referred to the results from the ongoing Kepler mission
to search for extra-solar planet candidates, which has already demonstrated that solar systems are common and recent results from the Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) mission to Mercury
, which has detected the potential for water ice and organics on that planet, something that had previously been considered highly unlikely. Whilst there’s no definitive evidence yet of the existence of life other than on Earth, Grunsfeld said these findings
“say that the building blocks of life...sources of carbon, water, and energy are prolific throughout the universe. To me, that makes it even more exciting in this quest to find out if we are alone in the universe. We’re on our way. The Curiosity rover is an amazing step to a place in our solar system that I think has the highest probability of revealing whether life ever existed or whether at least habitable conditions existed on Mars.”