Physics: Principles and Problems


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Robots From Space Are Starting to Land
February 2004

It's true; robots are descending from the sky, ready to unleash other, smaller robots that will roll and probe and dig. They have flown through the vast reaches of interplanetary space and are just now touching down. It's even possible that these advanced robots are only the first visitors from the distant planet where they were made. They may, in time, be followed by their creators. It's beginning to look like an invasion--an invasion from the blue planet.

The blue planet, of course, is Earth. We ourselves are the highly intelligent species that have been sending these robots out, and their destination is our close neighbor in the Solar System, the rusty-red planet Mars. Since the earliest days of science, people have wondered whether there was life on Mars. They continue to wonder today--only this year, thanks to our robot invasion, we may just find out.

Mars Express!

By December of 2003, Mars Express will have gone into orbit around the red planet. "Mars Express" is a probe sent up by the European Space Agency, and when in place it will start firing radar signals and reading them as they bounce back. That will give us new information about the specific shapes of the Martian surface.

Even more exciting than that, Mars Express is sending out a smaller module called Beagle II, that will bump and roll its way through an actual landing. Beagle II will do one step better than just looking at Mars from above. It's going to dig into the Martian soil and see what's there.

Opportunity is On the Way

At the same time, Spirit and Opportunity are on the way. These two are rovers being sent to Mars by NASA, the American space agency. When they get there they will drive across the surface of the planet like little dune buggies. Spirit and Opportunity will be testing the soil at two promising sites--each of which looks, from above, as if it once was covered by water.

So What Does Life on Mars Have to do with Water?

The question of whether there is water on Mars may seem . . . well, kind of dry. After all, where are the crystal cities, the floating palaces of science fiction? In the realm of real science, though, water is central. And finding it would be almost as exciting as a crystal city or two.

That's because places with liquid water are good places to look for living things. We do not know all the ways that life may come about, and surely there are surprises in store. But from what we know about our biosphere here on Earth, life and liquid water go hand in hand.

This actually makes Mars an excellent candidate--if not the Mars of today, than perhaps Mars as it was a few million years ago. From previous fly-bys, planetary scientists have spotted tell-tell signs that there was once water on Mars; perhaps even enormous oceans. There are geological formations that look a lot like lake beds, like channels, like canyons (canyons are formed by water), like gullies. The planet seems to have been carved and shaped by flowing water.

The strange thing is, there's no water there now. Some is frozen into the polar ice caps, but those dramatic lake beds and gullies are all bone dry. Is Mars fooling us into thinking oceans were there when they weren't? Are these shapes formed by other natural processes? Or was there liquid water once, and possibly life?

Or, most exciting of all, are there microbes living under the surface layer of the soil even now--honest to gosh Martians?

Only the Robots Can Tell

We won't know until we scoop up some Martian dirt and examine it . . . or until our intrepid mechanical explorers do it for us. So keep an eye out this year for news from Mars Express, Beagle II, Spirit and Opportunity. Alien robots are, in fact, dropping from the skies onto the dusty red landscape. And soon, we may know whether anyone living there is bothered by the intrusion.

Many observatories welcome visitors on special nights. Look in your newspaper or ask an adult to help you find out whether there is a local observatory where you could take a look at Mars. Since Mars has recently come the closest to Earth it's been in 60,000 years, chances are good you can still get an excellent view.


  • Cowen, Ron. "Martian Invasion: Probing lively puzzles on the Red Planet." Science News: November 8, 2003.
  • European Space Agency
  • NASA


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Physics: Principles and Problems