Ancient Martian Lake May Have Contained Life; NASA Mars Rover Searching For More Clues
Scientists say an ancient lake on Mars, discovered by NASA's Curiosity rover, could have, in theory, supported extraterrestrial life. For more than a year, the rover has been combing the surface of the planet in search of water and organic molecules. On Monday NASA researchers published a collection of its findings in the journal Science, including a description of this so-called Yellowknife Bay, nearby to which it now seems like likely potable water once stood.
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"Not only has Curiosity accomplished its primary goal of finding evidence for an ancient environment that could have supported life, but it also has provided evidence habitable conditions existed more recently than expected and likely persisted for millions of years," NASA said in a summary of its research. Scientists are quick to add that this only proves life could have existed in theory. And if organic matter is discovered in the crater near the surface, not even that is conclusive evidence of Martian life: Ancient earth rocks spewed into space have often collided with planets and moons, carrying earthling organics with them.
Yellowknife Bay has more than just low-acid, low-salinity water. It has an energy source. According to NASA, there's a kind of mineral sludge - a mixture of iron, sulfur, and other elements - that combined electron donors and receptors to provide power. The electron exchange acts "like the two poles of a battery," NASA says. It's already known that Mars has hosted water and still contains it today, though only the frozen kind at each ice cap. Scientists believe that more than 4 billion years ago, Mars could have had enough water to form clay minerals and life. This newly discovered lake probably existed less than 4 billion years ago, concurrently with the oldest-known terrestrial lifeforms.
But NASA isn't just trying to find out if life is or was on Mars; it's trying to put it there, too. So Curiosity has been measuring the radiation exposure during the ride out and ever since it landed on the surface. The dosage hasn't been fatal so far, but Mars also hasn't suffered any unexpected and largely unpredictable solar storms. Ninety-five percent of the radiation has come from cosmic rays. NASA estimates that the total radiation exposure for a human on a round-trip mission to Mars would be about enough to raise that person's risk of fatal cancer by 5 percent. The current acceptable increased risk for low-orbit missions is 3 percent. "The agency is working with the Institute of Medicine of the National Academies to address the ethics, principles and guidelines for health standards for long duration and exploration spaceflight missions," NASA said.
Curiosity is about 16 months into its 23-month "primary mission" phase. After that, it will continue exploring Mars indefinitely. "It is exciting to think that billions of years ago, ancient microbial life may have existed in the lake's calm waters, converting a rich array of elements into energy," said Sanjeev Gupta, of Imperial College London, one of the research team members, in a statement. The next few steps may be critical. "The next phase of the mission, where we will be exploring more rocky outcrops on the crater's surface, could hold the key whether life did exist on the red planet."
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