Did Mars once have the conditions for life?

How would you fancy taking a trip to the red planet? Julia Ravey spoke to author of "The Red Planet" and planetary geologist, Simon Morden, who gave her an insight about what life might be like on our neighbouring planet, and told her how he once held a bit of Mars in his hands...

Simon - I was working on achondrite meteorites. These are igneous type rocks formed from molten rock, but out in space. I was looking for raw iron and nickel specs inside this meteorite, and I didn't find any. And I thought that was really disappointing. What I did find was I found a lot of iron oxides. So I just wrote a note saying, I think this sample is contaminated, it's been weathered. And it was six months later that I discovered that I was half right in that yes, that meteorite had indeed been weathered, but it hadn't been weathered on earth. It had been weathered on Mars.

Julia - If I were to land on Mars today, what would I be met with? What would I see? And how would I feel?

Simon - First of all, I definitely advise you to go in a spacesuit because the average pressure on Mars is six millibars. That's probably as good as vacuum as you'll get. It'll be cold. Summer temperatures on Mars get up to 20 degrees or so, but on that same day, just before dawn, you'll be looking at -80 C because of the cold. All of the water vapour in the atmosphere has basically frozen out. It's still there as ice under your feet, but there will be none in the air at all. It will be baron and you will have not seen anything like it at all. Not that you can see very far of course, because the curvature of the planet is such that if you're standing there on the surface of the planet, you will only able to see to the horizon, which is five miles away.

Julia - If we look back at Earth, it's had great freezes, it's had times when it's been extremely hot. Has Mars had similar changes to its terrain and to its climate over time as well?

Simon - Mars, because it formed further away from the sun, ended up with a big load of dust and gas and ice that went into the planet when it was formed, which meant that its atmosphere was ridiculously big to start off with. But the planet that small couldn't hang onto an atmosphere that big. So as that atmosphere was stripped away into space and the surface temperature cooled, the pressure lowered, and it was able to rain. So there was a time when Mars was warm and it was very wet. Literally half of Mars was covered with an ocean. But the loss of its atmosphere was only ever going to end up with Mars getting basically meaner and colder as the years progressed.

Julia - And Mars has a pretty big volcano on its surface. So how did volcanic activity affect the planet?

Simon - Mars is the site of the highest volcano in the solar system, Olympus Mons, which is 24 kilometers high. That's 15 miles, which is pretty beefy. It's not the only ludicrously massive volcano on Mars. Apart from a small handful that are elsewhere on the planet, they're all centered on this one place called Tharsis. What you've essentially got with Tharsis is this lump of rock that you've stuck onto the side of Mars. And if you imagine that someone has taken a small planet and stuck it to the side of your own planet, it's going to make the planet wobble a bit. And that's exactly what happened with Mars. Tharsis wasn't originally on the equator, but because Mars is rotating once every 24 and a bit hours, the whole of Mars has literally twisted in its orbit so that Tharsis is now exactly on the equator.

Julia - And the biggest question about Mars, ala David Bowie, is there - or was there - life on Mars do we think?

Simon - I am going to say yes. If we look at the Earth's oceans and where we think life originated on earth, it will be in the deep ocean where you have things called black smokers. That's where sea water has gone down through cracks in the crust and it's met hot rock. Now, hot water is great at dissolving soluble minerals, very primitive plants and bacteria can use that chemical soup that comes back out to power their own reactions. If we look at Mars, we have exactly the same conditions. We have a deep ocean. We have cracks in the crust. We have hot rock underneath the crust. If we get down there and trundle around on the Northern Plains, looking for the sites of these black smokers, wherever they might be, we may well find the same kind of primitive life there that we would've done 4 billion years ago on Earth.