DW:
“Today we want to learn a little more about the Red Planet, so we've invited a geologist from the German Aerospace Center to tell us a little bit more. Ulrich Köhler, thank you so much for joining us here on Tomorrow Today.
Now, first, let's pick up where the report left off. We’ve just learned that Mars used to be a lot warmer. Certainly above freezing on the surface, and that there was perhaps, you know, liquid water there. What does this tell us now? How did that change? Why did that happen?”
Ulrich Köhler
“Well, what we see is that there has been a dramatic change in the climate of Mars, but that was about 3.5 to four billion(b) years ago, so we don’t know exactly how this worked and what the reason for that was. But it’s very obvious that before this change of climate we had much more favorable conditions for life. So there’s a slight chance that life had existed there and after that it was very hostile, it was acidic and it was not really wonderful, like on earth.”
“How would you compare the weather as such on Mars, in comparison to here on earth? Is there a comparison to draw?”
“Of course you can compare it, and the biggest difference is that it never rains in Mars.”
“OK. So there’s no precipitation or water.”
“There’s no precipitation at all and it’s very cold. It’s a very thin atmosphere and it’s a different atmosphere from earth. It’s carbon dioxide, and it’s no oxygen, no nitrogen, very little nitrogen, and so it’s a very hostile atmosphere for photosynthesis.”
“In other words, is there any other similarities that we could draw between Mars and Earth? How else are we alike?”
“There has been a lot of similarities, at least in the early time of past. Since we see the traces of water running over the surface. There are river beds. There are big channels. And there have been glaciers. There are polar caps with ice. So there have been similarities and we say that Mars is the most similar planet to earth in the solar system.”
“Now, NASA's Curiosity robot is currently collecting soil samples and finding out new evidence. What’s the latest there and what’s interesting about what they have found?”
“Well, that’s really a big story. A very successful story. They have selected a very good landing site. It’s a crater that was filled with water once. And on the bed of this lake there were sediments deposited and these sediments obviously have been in the water, a standing body of water with very neutral chemistry. It was not acid. It was not alkaline. So it was really good, favorable for life, maybe.”
“Favorable for life. That’s the key question I suppose. Now can you tell us a little bit about Mars Express and what you’ve had to do with that.”
“Well, Mars Express is the European mission, observing Mars since almost ten years. And we have made big regional surveys of the area and checked out for the traces of water and get more information about the climatic history of this planet.”
“Several Mars missions are being planned at the moment. If there was one outcome that you would really like to see out of one of these missions, what might it be?”
“Well, I hope that I will ever have the chance to investigate a sample from Mars here on earth. So the big thing would be in the next decade or so to return samples with an automated mission, with a robotic mission from Mars to our laboratories here, that are much bigger and could do all these investigations for traces of life that you could not do on the surface of Mars because the laboratories are too big, too expensive.”
“And finally, water is out there on Mars. Temperatures were moderate in the past, so what are the chances that there was actually life there?”
“I would say there are slight chances that in the early times of Mars, life might have existed on the planet, and the chances today are much slimmer.”
“Ulrich Köhler, thank you so much for joining us here at Tomorrow Today.”
(Interview: Anne O´Donnell)