Martian Blizzard! It’s Snowing on the Red Planet

New findings by a venerable NASA orbiter reveal a new dimension to Martian weather systems

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The south polar region of Mars from 24 Viking Orbiter images taken in 1977

Bit by bit, feature by feature, Mars is slowly revealing itself to us. A century ago, it was thought of as a planet crisscrossed by a network of canals — surely the great irrigation channels of a highly advanced race. Then we flew by for a first close look in the early 1960s and saw nothing but a cratered wasteland, little better than our own moon, save for the rusty color. But closer study has revealed much more. Mars was indeed once wet, as the dry seabeds and riverways that score its surface attest. Indeed, it still has some water, as new sightings of seasonal streaking down mountain faces caused by springtime ice melt show.

Now comes word from NASA’s Mars Reconnaissance Orbiter (MRO) that it’s snowing on the Red Planet — a lot. A massive, 500-km-diameter cloud persists all winter long over the planet’s south polar cap, dumping snow to blizzard-level depths. The catch: this snow isn’t made from water crystals, but carbon dioxide, and that’s just a little bit of what makes the new findings — and the way they were uncovered — so intriguing.

(PHOTOS: Snapshots of the Heavens: Amazing Astronomy Images)

As anyone near a tailpipe knows, atmospheric CO2 readily absorbs and radiates heat, making it synonymous with planetary warming. But sometimes even carbon dioxide meets its match, and that’s what happens at the south pole on Mars, where brutal winter temperatures of –125ºC make the notorious greenhouse gas flutter down from the Martian atmosphere as a dry, coarse snow similar to corn starch.

Researchers went looking for south-pole snow using the Mars Climate Sounder, a spectrometer aboard the MRO that measures the visible and infrared light emitted from cloud particles in the  atmosphere. In this case the infrared readings were crucial since Mars’ polar regions, like Earth’s, remain dark all winter. That means there isn’t enough visible light to study the area when the snow is falling.

Infrared, on the other hand, offers scientists something of a night-vision peek at the atmospheric particles above the south pole. On Mars, those particles do the same thing they do on Earth: scatter, absorb and radiate light. Conveniently, they do so at distinct wavelengths depending on the composition of the particle. Scientists can therefore compare those different wavelengths to identify the chemical makeup of any particular particle. This also allows them to map the cloud formations producing the snow — and those formations are impressive. The main cloud extends from an altitude of 32 km, down almost to the planet’s surface. Latitudes farther from the pole have smaller 9.7-km-by-9.7-km snow clouds that appear sporadically over a seasonal ice cap.

(MORE: Still More Robot Company for Mars)

“The smaller ones flash on and off for a day or two at a time, like little snowstorms,” says Paul Hayne, a geophysicist at NASA’s Jet Propulsion Laboratory and the report’s lead author. “If you had a thick enough space suit you could go skiing.” Hayne and his colleagues aren’t certain how deep the snow is, but they say it’s at least several feet, with radar evidence suggesting that some deposits are well more than a mile deep.

Don’t expect captivating snowflake patterns on Mars, however. Though the scientists aren’t certain what shape the falling snow takes, Earth-based experiments suggest they are solid particles — and they’re nasty ones too. Catch one of these on your tongue, and you’ve got instant frostbite.

This isn’t the first snowfall found on Mars; NASA’s Phoenix Lander mission detected falling water-ice at the planet’s northern regions in 2008. But until now, researchers had only indirect evidence of falling CO2 snow: a bed of CO2 ice on the surface, temperatures cold enough for CO2 to freeze and satellite-based scans suggesting the presence of dense CO2 clouds. “We had all those different lines of evidence,” Hayne says, “but this is the first direct three-dimensional observation of the cloud and the composition information.”

(MORE: What the Curiosity Rover Can Teach Us About Mars — and Earth)

The MRO discovery does more than reveal the increasing richness of Mars. It also helps explain more about the planet’s atmospheric engine. A portion of the annual CO2 snowfall sublimates back into the Martian atmosphere — a key element of Mars’ climate cycle since 30% of the planet’s atmospheric mass is exchanged between the polar caps and the atmosphere every year. “That’s a huge climate driver, and we don’t really understand how that process works on Mars,” says Hayne.

That could have implications for, yes, life. If more research reveals that additional amounts of CO2 are released from polar ice caps in similar cycles, that would mean periods of higher atmospheric pressure, making water more stable on the surface. That, in turn, would make polar investigations a NASA priority. Someday we may very well see a rover tricked out in snow tires, making its way across the plains on an improbable world where a greenhouse gas offers only chills.

PHOTOS: Photos from the Mars Curiosity Rover

PHOTOS: Martian Vistas: A Look at Curiosity’s New Home

23 comments
Jill Louis
Jill Louis

 

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Jill Louis

 

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loopy
loopy

This article is already dated as far as implying Mars has had a watery past. Was it last week that the latest indication is the supposedly evidence for water is now debatable at best and the features thought to have been water are now more likely volcanic in origin. But, the dry ice polar caps are indeed there, but, we've known that for decades.

LindaLuttrell
LindaLuttrell

I'd love to see Curiosity throwing snowballs!

Gol1ath
Gol1ath

 So what if we find snow there?  Who cares!!  There is water all over the universe!!!!  What if you found a fish on Mars??  You will eat it????  Stop wasting money on this and focus somewhere else like eliminating gas emission!!!

ERenger
ERenger

Problem with gas emission? 

Try Beano before a meal, and if the problem still develops, try Gas-X. I hope you feel better!

Gol1ath
Gol1ath

 If you are going to fart, go to the washroom man, cmon now.. gotcha! :)

Ryan Nay
Ryan Nay

 I think the gas emissions he's complaining about are those coming out of his face.

Gol1ath
Gol1ath

 Feel free to send NASA more money.....oh no?  I win, too bad so sad...you didn't think this though eh :)

Gary McCray
Gary McCray

Organic (plants) or nuclear powered reforming could easily convert the CO2 in the snow (or atmosphere) into available oxygen for colonists in enclosed habitats.

If they can find usable water (ice) in substantial quantity , it should be easy to support large human colonies on Mars.

Might be better than here in the long run.

Just saying!

ERenger
ERenger

If there is plentiful CO2 and H2O, then we have the ingredients for fizzy water, which is excellent for making drinks. 

If they can find usable Bourbon in substantial quantity, it should be easy to support large numbers of bars on Mars.You are right, Gary. It might be better than here in the long run!

rexslate
rexslate

Yes, I always thought that Mars Bars were the best! ... snicker, snicker ...

Gary McCray
Gary McCray

Got to admit I hadn't considered the mixological potential, but with the left over carbon from the CO2 and the H2O you have the raw ingredients for alcohol, I'm sure something could be worked out.

ChrisMay
ChrisMay

The CO2 cube won't work, but I'll take the single malt.  Can't be too picky from over 300 million miles!!

ChrisMay
ChrisMay

All of this might be true, but if you can find two ounces of scotch to one ounce of Drambuie,  stir with one punctured cherry (in juice), and just one freakin' ice cube, then I'd be in.

ERenger
ERenger

Mars has some fine single malts, but real Scotch has to be imported. Are you OK with a CO2 ice cube? 

ERenger
ERenger

Earth is nice, but I miss the change of seasons back on Mars. 

owl905
owl905

Basically a 'dry ice' mechanism.    Poor ol' Beagle never had a chance.  But the CSI team should find the pieces well preserved.

Jim Carroll
Jim Carroll

Daunting but fascinating - kudos to the deft and 'cool' report from NASA.  Those conditions make winter here in Canada seem even tropical.