|03-13-2013, 10:07 AM||#1 (permalink)|
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Your next trip to Mars
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What Snowstorms Are Like on Mars - Popular Mechanics
Snow on Mars Is Great for Skiing, Terrible for Snowball Fights
By Adam Hadhazy
NASA, Christine Daniloff/MIT News
March 12, 2013 9:55 AM
No human has ever set foot on the Red Planet, let alone tried building a snowman there. But clever data interpretation from orbiting spacecraft and landers, done recently, plus a lab experiment back in the 1970s, have helped unlock the secrets of Martian snow. Carbon dioxide snow falling on Mars would look like a mist or a fog, shown in this artist's rendering, instead of the big clumps of water ice snowflakes you could catch on your tongue here on Earth.
Here in the United States, spring's thaw is right around the corner. In Mars' northern hemisphere, however, winter is just getting started, and that means it's time for snow. Although Mars is millions of miles away and still poses plenty of scientific riddles, thanks to discoveries over the last year, researchers think they now have a pretty decent idea of what Martian snow is like.
In short: Mars has two kinds of snow, and one isn't like Earthly snow at all.
Most of the snow that reaches the ground and accumulates on Mars is not made of frozen water, but of frozen carbon dioxide. It's a purer version of the "dry ice" that you might use to fog up a punch bowl at a Halloween party. And when it comes to frozen CO2, you can forget the beautifully varied, six-sided, H20 crystal snowflakes that fall from our skies. Instead, the carbon dioxide solidifying in Mars' thin atmosphere likely forms cubic pellets with the corners lopped off and replaced by triangles, called cuboctahedrons.
Furthermore, the Red Planet's white stuff is probably small compared to our everyday terrestrial snowflakes. Carbon-dioxide snow is microscopic, and the second variety, the rare water-ice snow on arid Mars, is similar to the "diamond dust" in our polar regions.
In northern Martian climes carbon-dioxide snow is a mere 8 to 22 microns in diameter. Molecules falling on the southern highlands, meanwhile, range from 4 to 13 microns. It's microscopic in both cases, and about the breadth of a human red blood cell. "The particles are so small they wouldn't be like flurries," says Kerri Cahoy, an assistant professor of aeronautics and astronautics at MIT and co-author of a recent paper on Mars snow. "The snow would really be like a very thin fog that you'd see."
Alas, for future colonist children, snowball fights on Mars don't look like a realistic option. Superfine, frozen carbon dioxide powder mixed with a bit of water-ice packs poorly. "It would be next to impossible to make a snowball," says Daniel Cziczo, an atmospheric chemist at MIT. "Just like on Earth when the temperature gets too cold—below zero degrees Fahrenheit—you don't get the sticky snow that has some liquid water in it that you need to make snowballs. They'd be so powdery they'd fall right apart."
For the same reasons, however, sledding, skiing, or snowboarding on Mars could be X Games–level gnarly. "I think it would be quite good for sledding on Mars when there's snow on the surface," says Jim Whiteway, a professor of space engineering at York University. "It would be quite slippery compared to what we have on Earth."
But God demonstrates his own love for us in this: While we were still sinners, Christ died for us. -Romans 5:8-