A Curiosity rover selfie. Snapped in Gale Crater on the surface of Mars on October 31, 2012.

Credit: NASA

Did Life On Earth Begin On Mars?

August 6, 2013

As it turns out, we might all be Martians.

That’s the hunch of a team of scientists at Harvard, MIT, and Massachusetts General Hospital. Christopher Carr is a research scientist at MIT for that team, which is known as the Search for Extraterrestrial Genomes (SETG). He said the big idea driving the research is that if life on Mars exists, it could be related to us.  

If that sounds far-fetched — a little more Isaac Asimov than Stephen Hawking — consider what our solar system was like about 3.8 billion years ago, during a period called the Late Heavy Bombardment. 

Cosmic rocks, comets, and asteroids were pelting Mars and Earth. All of those impact events produced a lot of debris. And that debris is the key to the SETG team’s theory that life on the Red Planet could be related to life on Earth. 

“During this time, Mars was much more similar to Earth,” Carr said. “The idea is that if life had arisen either on Mars or on Earth it could have been transferred by these meteorite impacts."

And with 99 percent of those rocks coming to us, if life was transferred between the planets, chances are it came from Mars.  

Carr wants NASA to go looking for it, by including a SETG instrument on board its next Mars Rover, which is scheduled to launch in 2020.

“We’d be looking for something similar to microbial DNA. What we are working on developing into our instrument is the ability to go from a soil or ice or brine sample, isolate nucleic acids and the sequence them, just as we do with samples all over the world,”

If the scientists find what they’re looking for on Mars, then they’ll compare the genome sequences from the Martian samples with all known genome sequences here on Earth. Similarities in the genomes would suggest that there are distant relations between life on Earth and life on Mars, Carr said. 

There is a catch to the SETG technology, though. It will only spot DNA in microbes that are still alive or recently deceased. Thankfully, in planetary time, “recently” constitutes a pretty big window: about one million years.

Up until now, the search for life on Mars has been a search for evidence of life that might have existed billions of years ago.

Carr admitted that shifting gears to a search for current life on Mars is a high-risk endeavor. But, it's also one with a potentially high reward. It’s a gamble that he said is worth taking right now.

“It will be a real shame if decades from now we find out that there is life on Mars and it’s like us,” Carr said. “And, furthermore if we do find some evidence, I think it will give us a really good shot in the arm in terms of our interest and commitment to searching that planet.”

So if NASA does decide to go for it? What are the chances that we’ll actually hit the jackpot?

“I'm not willing to put a probability on it. But if it's there I want to find it. I guess what I'd say is. 'Don't bet against the microbes," Carr said.

Check out this video of highlights from Curiosity's first year on Mars:

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