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Life on Mars?

March 15th, 2013

Mars' rock sample drilled by Curiosity. Image credit: NASA/JPL-Caltech/MSSS

by Jason Kendall

NASA’s Mars Science Laboratory, named Curiosity, had some really big news this week.  They found that Mars was once a place where life could have arisen.

Wait a second, that’s a strange sentence.   Did they find life?   Sadly, no.  Did they find fossils?  Again, no dinosaur bones or ancient camel remains like those recently found here .  Did they find puddles of water and moss and plants and bacteria?  Well, sorry, no again.

Curiosity self-portrait. Image credit: Curiosity! And NASA/JPL-Caltech/MSSS

So what did they find? And why’s it such a big deal then?

Basically, what they found was a well-set dinner table for some very picky dinner guests.   Curiosity was at a location called Yellowknife Bay, where it’s been scooping up Martian soil, drilling into rocks, sifting it with a sifter, and looking at it really closely.

You can do the same thing at home by going out into your yard and looking for a patch of soil that your fingers can easily pull up.  Look at the soil with a magnifying glass.  What do you see?  Hopefully some soil, some rocks, and maybe some other things like seeds, roots or even little bugs.  Now, on Mars, there are no seeds or root or bugs, so let’s push those out of our hand, and look just at the soil and rocks, which Mars does have.

On Earth (this particular spot is in Australia) there are some similar environments as Mars' Yellowknife Bay. Image credit: NASA/JPL-Caltech/Ames

Brush away even the soil, what are you left with?  Maybe some little pebbles and some glittering rocky dust.  If you took that to a chemist at a laboratory, who looked with a really good microscope, we might find that on these little pebbles there are some microbes and bacteria that live on the rock and eat the rock as food.

There will be some kinds of rock that don’t yet have such bacteria, and some which once did, but the bacteria have moved on after eating their fill.  These are the kinds of rocks that Curiosity has found.  They found rocks that, if we took some normal-looking, rock-eating bacteria on Earth, put them on the rock, and flooded the rock with a lot of water, the bacteria would be happy and grow and eat the rock.

Comparison of water-rolled rocks on Earth and Mars (they look a lot alike!). Image credit: NASA/JPL-Caltech/MSSS and PSI

Combine this with what was found a couple of months ago — that at Gale Crater there are rocks that were clearly smoothed by running water — and you have a place on Mars that was suitable for life to arise.  In fact, Curiosity’s team has determined that the water that was once in Gale Crater would have even been drinkable by you and me!

Remnants of an ancient Stream bed on Mars. Image credit: NASA/JPL-Caltech/MSSS

Wow!  Does that mean that life is there now and that life could be there now?   Probably not.  Mars is a tough place, and besides, Curiosity is not built to look for that.

What we can only say is that about 3 billion years ago on Mars, in Gale Crater, there was a lot of water, and that the rocks that were there and the chemicals in those rocks could have supported some of the same simple forms of life that we have here on Earth. Now, today it’s too dry and too cold to support surface life, even of the simplest kind.

We still don’t know whether life actually arose on Mars, but we are now certain that Mars could have been a bacteria’s favorite restaurant.  The table was set, the waiters were waiting, the doors were open, and the music was playing.  Did any microbes end up nibbling on those tasty non-oxidized rocks and sulfates and sulfides?   We don’t know.  But at least we now know it could have happened.

Click here for the full NASA article. To read HTE’s previous stories on Curiosity, click here  and here .

For other cool Mars videos, click here to be taken to NASA’s Jet Propulsion Laboratory’s Education website.

Jason Kendall teaches Astronomy and Physics at William Paterson University in New Jersey.  He loves the planets and space and is glad to write stories about Space for HTE Kids’ News. And he’s happy to answer your questions!

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