Pure Martian Ice

Friends, there's water--lots of pure, frozen water--in Mars's southern polar ice cap. How much water? Enough to cover the entire Red Planet with a sea 36 feet (11 meters) deep if the ice ever melts. At least, so says an international team of scientists from the world's elite space agencies.

How did they measure the water content of an ice cap on Mars? They used a standard technique for studying glaciers on Earth--and a special, souped-up radar system on the European Space Agency's Mars Express spacecraft. To see the colorful ice cap map they made, click here.

Big, Thick, and Pure

The ice cap map covers an area larger than Texas. Look closely and you'll notice that the ice is up to 2.2 miles (3.5 km) thick in some places. What you can't tell, but the researchers can, is that the ice also appears to be remarkably clean--composed of around 90 percent pure frozen water.

Most experts didn't expect the ice to be that thick or that pure. But few find the sheer volume of water all that surprising. Mars scientists have long known that the planet's poles are icy places. And recently, evidence of Martian moisture has been pouring in.

More Wet Spots

The radar team now plans to sound out Mars's northern polar ice cap, which may well contain more water than the southern one. That's a lot of water. But lead researcher Jeffrey Plaut says it's still just a fraction of the fluid that once flowed over Mars's surface. He thinks it took "about 10 times or maybe even 100 times" as much water as the caps now contain to shape modern Mars.

Of course, finding even a fraction of that water might move us a step closer to finding life on Mars, too. Water, after all, is an essential ingredient for life as we know it. But think little green microbes, not little green men. And don't expect an invasion anytime soon (other than the virtual one below).

--Steve Sampson