Search For Life Number One Priority of Mars Robotic Explorers

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Search for Life on Mars a Top Priority for Robot Probes, Scientists Say
By Charles Q. Choi
Astrobiology Magazine Contributor
posted: 11 November 2010
06:11 am ET
The first and only attempts to search for life on Mars were the Viking missions launched in 1975. Now scientists are suggesting the next decade of robotic probes sent to the Red Planet should make the search for life the highest priority.

After the Viking missions, the general consensus was that cold, radiation, hyper-aridity and other environmental factors ruled out the chances for microbial activity on or near the surface of Mars. This assumption — based largely on how Viking's instruments did not detect organic compounds that would have indicated Martian life — has been reinforced by each follow-up mission since then.

The Mars Science Laboratory, scheduled for launch in 2011, is dedicated to searching for evidence that the Martian environment was once capable of supporting life on the Red Planet. However, some scientists argue the strategy for Mars exploration should center on the search for life itself – "extant" life that is either active today or is dormant but still alive.

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"There is no human task more significant and profound than testing if we are alone or not in the universe, and Mars must be the first place to look, as it is just facing our front yard," said astrobiologist Alberto Fairen at the SETI Institute and NASA Ames Research Center. "Finding life on Mars would be the most important scientific achievement of this century."

NASA's Viking vanguard

The Viking landers had detected organic molecules such as methyl chloride and dichloromethane, but these had been dismissed as terrestrial contamination – namely, cleaning fluids used to prepare the spacecraft when it was still on Earth. [Gallery: Viking Missions to Mars]

The Phoenix lander spotted magnesium perchlorate in the soils, which can destroy organic residues. This discovery has caused scientists to rethink the Viking assumptions. Because Viking heated its samples, it could have caused a chemical reaction between perchlorate and any organics present, thereby destroying the organics.

The recent detection of methane on Mars has also revived the possibility of past or even extant life just below the surface, since life is one of the primary producers of methane on Earth.

As hostile as Mars might be for life, numerous examples exist of life surviving in extreme environments on Earth. For instance, microbes are seen in cold, dry soils of the Antarctic Dry Valleys. These soils are arranged into a layer of dry permafrost overlying ground ice, a structure similar to some soils on Mars. Debris-rich ice layers in glaciers trap water films and mineral dust that can serve as a basis for life on Earth, and similar layers are seen at Mars' northern polar deposits.

Microbes even live in salt knobs in the hyper-arid Atacama Desert in Chile, which is often described as similar to Martian soils.

These analogs of Mars on Earth suggest there are relatively few areas on Mars that could support life — ice-cemented ground, massive ice deposits and certain porous salts.

"Probes have been sent to regions of Mars where ice-cemented ground is common — this was the case of Phoenix, in the northern plains," Fairen said. "Other environments, such as hundreds of regional accumulations of chloride salts, have been discovered very recently, only three years ago, and are dispersed on the ancient southern highlands. In any case, there have been no attempts to analyze any of these environments with modern biological instruments to search for life, extant or extinct."

Robot invasion of Mars

Fairen and his colleagues recommend a new strategy for the next decade of robotic investigations on Mars, one in which the search for extant life is the first priority.

"We call for a long-term architecture of the Mars Exploration Program that is organized around three main goals in the following order of priority — the search for extant life, the search for past life, and sample return," Fairen said.

The researchers envision probes targeting the kinds of areas where life might be found, and carrying instruments that can provide indisputable evidence – such as actual microbes – for the presence or absence of life. Robotic missions in search of spores, dormant life or organic remains could, for instance, drill a few yards down to reach ice-rich layers shielded from the high levels of radiation at the surface and use microscopes to examine their finds.

A mission aimed at looking for extant life would also be ideal for finding any extinct life, since dead organisms likely would be found in the same places as live ones would. Since soil bacteria in the Atacama Desert are spread out in a patchy manner, any new missions to search for life on Mars should incorporate a rover. Landers should also be used to return samples, if at all possible.

"The technology is ready," Fairen said. "We only need a new impulse and more ambition."

The scientists detailed their strategy online Oct. 7 in the journal Astrobiology.

Photos: Viking Missions to Mars, Mars Rover Discoveries
Bringing a Bit of Mars Back Home
Meteorite-Based Debate Over Martian Life Is Far from Over

A Historical Moment That I Have Waited For All My Life; NASA Admits There Is Life On Mars

Mystery ... scientists are already planning more missions to Mars
By BRIAN COX
Sun Professor
TELL-tale signs of water on Mars are incredibly exciting because they make the discovery of alien life on our nearest neighbouring planet much more likely.

On Earth, life exists in the most unexpected places. In the oceans, miles away from sunlight, living things thrive on a diet of rock and heat from volcanoes on the sea bed.
By RHODRI PHILLIPS
and PAUL SUTHERLAND, Sun Spaceman
Published: 28 Apr 2010
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NASA scientists last night unveiled compelling evidence of life on Mars.
A special mission to the Red Planet has revealed the likely presence of a form of pond scum - the building blocks of life as we know it.

NASA unveiled the results of the recent Opportunity and Spirit probes sent millions of miles through the solar system to discover signs of extraterrestrial life.

The results are so promising boffins have already planned a host of other missions to discover whether there is extraterrestrial life in the universe.

The recent missions have gathered evidence of sulphates on Mars, a strong indication there is water on the planet and therefore life.

Previous missions to Mars have concluded there is probably water on the planet.

But the NASA boffins said the recent missions have gone further than any others in proving there is life on Mars.

They were particularly excited about the discovery of a sulphate called gypsum which, it has emerged recently, is found in large quantities among fossils in the Mediterranean.

Jack Farmer, researcher at the Arizona State University, in Tempe, Arizona, said he was "optimistic" there was - or had been - life on Mars.

Another of the scientists Bill Schopf, researcher at the University of California in Los Angeles, added: "One, thanks to Opportunity and the rovers and orbital imaging it is clear that there are literally vast areas of Mars that are carpeted with various sorts of sulphates, including gypsum.

"Two, it turns out on earth there just hasn't been hardly any work done at all to show whether gypsum ever includes within it preserved evidence of former life.

"The age doesn't matter. We just didn't know that fossils and organic matter and things like that were well preserved within gypsum.

"So, three, it turns out that now we have made that first step we are going to find out how widespread it is in other sulphate deposits on earth.

"And those lines of evidence will then give us a way to justify going to Mars and looking at gypsum because it looks as though based on these findings that is going to turn out to be a really excellent place to find evidence of ancient life, regardless of age, if in fact it is there."

Five experts took part in last night's press conference to celebrate 50 years of astrobiology research.

Dr Steve Squyres, of Cornell University, Ithaca, New York, said the only way of being sure there is life on Mars was to bring back a sample of Mars rock.

He also said that the detection of methane in the martian atmosphere - as revealed exclusively by The Sun - raised the possibility that there was still life on Mars today.

"Methane is a molecule that should go away very quickly. We need to send a mission to find out if the source is biological.

"We also need to send a mission to return samples from Mars. That would enable scientists to find out whether Mars might ever have harboured life.

"If we are ever going to show if there was ever life on Mars, I think we're going to have to study samples back on Earth."

Almost 30 other NASA missions to discover life in space - including one to bring back rocks from Mars - have already been planned.

There are also plans to visit Jupiter's moon Europa to explore its deep underground ocean and a moon of Saturn, Enceladus, which spouted ice volcanoes.

Long-term missions will also return to Saturn's biggest moon Titan, sending a balloon flying through its atmosphere and landing a probe in its surface lakes.

Future missions would also visit comets.

NASA scientists have been searching for extraterrestrial life on other planets for some time.

Last November the space organisation launched the Kepler space telescope to look for Earth-size planets in this galaxy.

The telescope is on a three-and-a-half-year mission to find planets.

NASA has so far been able to download data - but many believe there are aliens out there.

British physicist Stephen Hawking said this week aliens might be traveling through the cosmos right now - but he warned they might have evil intentions.

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