Credit: NASA
Photo: BBC World / Copyright
Jonathan Amos
BBC News Science Correspondent
Scientists are still cautious about the existence of life on Mars, but recognize evidence identified by Curiosity
The Curiosity robot – created by NASA to explore the surface of Mars -. identified methane in the planet ‘neighbor’ to Earth, which could be a sign of life there in the past or even the present
The robot detected the constant presence of very low levels gas, but also recorded “peaks” of much higher concentration.
The fact that there methane on Mars is intriguing because, on Earth, 95% of this gas comes from microbial organisms such as bacteria.
Researchers also hypothesized that the presence of these molecules on Mars can be a life existence signal on the planet.
The Curiosity team could not identify where exactly the methane had been found but the more likely it is that you came from underground stocks that are regularly raided by the robot.
The project scientist Sushil Atreya said it was possible that the so-called methane hydrates were involved.
“These things are like molecular cages of water-ice, where methane gas is trapped. From time to time, these molecules could be disrupted, perhaps by some mechanical or thermal stress, and methane gas would be released to find their way through cracks or fissures in the rock to enter the atmosphere, “said the professor at the University of Michigan . BBC News
The question that still remains in the air is how the methane would have come to hydrate reserves
It may have come from microorganisms;. may also have come from a natural process such as chemical reactions resulting from the interaction of water with some types of rock formations. So far, everything is speculation. But at least the Curiosity has identified the gas.
Samples
fact the robot have taken to detect the gas – which had already been observed by satellites in orbit Mars and telescopes on Earth -. caused some strangeness
The Curiosity is in a crater on the surface Mars called Gale Crater.
Robot identified presence of methane on the surface of the Red Planet
He has sucked the air of Mars to investigate its components from which landed on the planet in August 2012 .
For gases that have very low concentrations in the atmosphere, the robot uses a special technique that expels the most abundant molecule – carbon dioxide -. before analyzing the sample
This has the effect of enriching and expanding any chemical waste.
And to do this with methane, Curiosity found that there is a constant presence of something close to 0.7 parts per billion volume (ppbv).
“The background suggests that about 5,000 tons of methane in the atmosphere,” said Dr. Chris Webster of NASA’s Jet Propulsion Laboratory, who led the research.
“You can compare this with the Earth, where there are about 500 million tons. The concentration here on Earth is about 1,800 ppbv. “
Life
methane peaks detected by Curiosity occurred on four occasions during the course of a period of two months.
They ranged from about 7 to 9 parts per billion volume.
It is likely, the team, the gas is being released in a place relatively close to the robot, either in inside the crater or outside.
The weather station’s Curiosity suggests that the gas is coming from the north toward the crater rim.
One way to investigate whether the Mars methane has biological or geological origin would study the types, or isotopes, of carbon atoms in the gas.
On Earth, life favors a lighter version of the element (carbon-12) on a more heavy (carbon-13). A high proportion of C-12 in relation to C-13 in ancient rocks on Earth was interpreted as evidence that there was biological activity in our world four billion years ago.
If scientists discover similar evidence on Mars, it would be surprising. But unfortunately, the volume of methane detected by Curiosity are simply too small to do this kind of experiment.
“If we had enriched our sample during one of the peaks, we could have had a chance to examine these isotopes” explained Dr. Paul Mahaffy, chief investigator of Curiosity Surface Analysis on Mars (SAM).
“I think there is still some hope. If methane back, and we can enrich it, we’ll certainly be trying. “
Long search
Another great discovery of Curiosity is the robor also confirmed the existence of organic compounds (carbon-rich) in rock samples.
It is the first time they are identified organic elements in the Red Planet’s surface materials.
The robot found evidence of chlorobenzene on a piece of pulverized rock extracted from a mudstone (type of sedimentary rock ) nicknamed Cumberland.
Chlorobenzene is a carbon ring with five atoms of hydrogen and a chlorine atom ligados.A team can not be sure if the element was specifically present in Cumberland or was produced during heating in the analysis. But even if the latter, scientists seem confident that the molecule would at least carbon derived from larger structures than those that were in place.
Again, scientists are interested in confirm the existence of such organic products because life as we know it can exist only where there is capacity of carbon molecules exchange.
If they are not present, then there can be no biology. However, as with the identification of methane, this alone is not an automatic indication of life on Mars, now or in the past because there are plenty of abiotic processes that will produce complex carbon structures as well.
“It’s a great day for us – is a kind of 10 years of hard work crowning – in that report that there is methane in the atmosphere and there are also organic molecules in abundance in the subsurface,” said Curiosity project scientist John Grotzinger
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