The Latest Sign Of Martian Life

It’s been a good week for the rover:

The lake, found at a spot called Yellowknife Bay in the Gale Crater, existed around 3.6 billion years ago and could have lasted for hundreds of thousands of years. The Curiosity rover’s analysis discovered sedimentary rocks with evidence of carbon, hydrogen, oxygen, nitrogen, and sulfur, elements that suggest the lake could have sustained life. The findings were published Monday in a series of six papers in the journal Science.

This isn’t the first time scientists, or Curiosity rover for that matter, has found evidence of large bodies of water on Mars. But it is one of the first times scientists have specifically outlined an environment in which life could have survived.

The lake would have been “suitable for a wide range of microbial lifeforms” – specifically, oddball microbes known as chemolithoautotrophs:

Chemolithoautotrophs do not need light to function; instead, they break down rocks and minerals for energy. On Earth, they exist underground, in caves and at the bottom of the ocean. … “For all of us geologists who are very familiar with what the early Earth must have been like, what we see in Gale really doesn’t look much different,” Curiosity chief scientist Prof John Grotzinger told BBC News.

Joseph Stromberg sees the latest discovery as “yet another vindication of Curiosity’s mission, which is to determine the planet’s habitability.” NASA also has good news for anyone hoping to see the Gale Crater firsthand:

The risk of radiation exposure is not a show-stopper for a long-term manned mission to Mars, new results from NASA’s Curiosity rover suggest. A mission consisting of a 180-day cruise to Mars, a 500-day stay on the Red Planet and a 180-day return flight to Earth would expose astronauts to a cumulative radiation dose of about 1.01 sieverts, measurements by Curiosity’s Radiation Assessment Detector (RAD) instrument indicate. To put that in perspective: The European Space Agency generally limits its astronauts to a total career radiation dose of 1 sievert, which is associated with a 5-percent increase in lifetime fatal cancer risk.

“It’s certainly a manageable number,” said RAD principal investigator Don Hassler of the Southwest Research Institute in Boulder, Colo., lead author of a study that reports the results in the journal Science. A 1-sievert dose from radiation on Mars would violate NASA’s current standards, which cap astronauts’ excess-cancer risk at 3 percent. But those guidelines were drawn up with missions to low-Earth orbit in mind, and adjustments to accommodate trips farther afield may be in the offing, Hassler said.