What two discoveries suggest about life in the solar system

Science correspondent Miles O’Brien joins Judy Woodruff to discuss two space stories that center around the search for life and how it began. NASA’s Dawn spacecraft arrived in orbit around the dwarf planet Ceres, which scientists believe shows signs of life-sustaining water. Meanwhile, new research found that Mars once had enough water to cover 20 percent of the planet.

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    Let's close out our Friday with the continuing search, not just for life, but for a better understanding of how life began.

    There's a connection in two space stories today. This morning, NASA said its Dawn spacecraft arrived in orbit around the dwarf planet Ceres, a journey of more than 300 million miles that lasted more than seven years. Ceres lies in an asteroid belt between Mars and Jupiter.

    And, yesterday, new research found that Mars once had even more water than we realized, enough to cover 20 percent of the planet and larger than our Arctic Ocean.

    We're joined by science correspondent Miles O'Brien.

    So, Miles, tell us, what are they looking for on this tiny planet?


    Well, wherever you look in the world on our world and you see liquid water, you will find life. It doesn't matter where. You can be in the hot acidic springs of Yellowstone or deep below the ocean in the darkest places. If there's liquid water and an energy source, there is life.

    And so this is what ties these two stories together. Dawn is arriving at Ceres. And there is lots of evidence that Ceres has quite a bit of water, perhaps an ice crust, perhaps even water geysers. A dwarf planet, Judy, has a molten core. And so there is reason to believe that there's heat beneath the surface, which means there could be liquid water, which means there could be things alive there which date back 4.5 billion years.

    It's kind of mind-boggling, but this is like a snowball that's been in the deep freeze, but it has a liquid core. And so understanding what's going on there will tell us a lot about the origins of life here and maybe elsewhere.


    So, they think this is going to answer some big questions about the cosmos?


    Well, think about Earth as a soufflé, right? And you want to figure out what the ingredients are of this soufflé that makes us.

    It's kind of hard to do if you have got the soufflé is cooked. But if you can go to the freezer and look at all the ingredients and see what is inside the soufflé, you are going to try to figure things out, and you will be able to figure things out a little better.

    Well, the asteroid belt is the deep freeze for 4.5 billion years ago, when the solar system became what it — got started. And so, if we go there and we look at what's in the freezer, we're going to see the ingredients. And Ceres is a good place to go.


    And then separately, Miles, the finding of this body of water or what once was a body of water, they think, on Mars, how does this expand our understanding of the solar system and what happened?


    Well, of course, the story of water on Mars is a story we have been telling for a long time.

    You can go back to Giovanni Schiaparelli and the canali that he observed, which ultimately led us to think there were Martians and led us to "The War of the Worlds." But we have learned in more recent years, just by looking at the features of Mars, that it looks like it was etched out of water, but where did the water go? That has been the big question.

    A series of missions, NASA missions, including most recently the Curiosity rover, have shed a lot of light on this and have said beyond a shadow of a doubt that there was water there on the order of three billion years ago. Well, this latest paper is really exciting, because they used telescopes based on the ground to measure the amount of heavy water in the atmosphere.

    And by figuring out the ratio between the heavy water and the light water, they were be able to backtrack 4.5 billion years ago, and come up with an ocean about the size of our Arctic Ocean, 5,000-feet deep and most important, present for 1.5 billion years. And that's enough time, at least on this planet, for life to take hold.

    So you have got a warm place, a wet place and a billion-and-a-half years of this big ocean. So, surely — well, I will say surely, the scientists won't — but I'm going to be willing to bet you there are tiny fossils there somewhere.


    Miles O'Brien, thank you.


    You're welcome.

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