A spacecraft orbiting Mars has detected carbon dioxide snow falling on the Red Planet, making Mars the only body in the solar system known to host this weird weather phenomenon.

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The snow on Mars fell from clouds around the planet's south pole during the Martian winter spanning 2006 and 2007, with scientists discovering it only after sifting through observations by NASA's Mars Reconnaissance Orbiter (MRO). The Martian south pole hosts a frozen carbon dioxide — or "dry ice" — cap year-round, and the new discovery may help explain how it formed and persists, researchers said.

"These are the first definitive detections of carbon-dioxide snow clouds," lead author Paul Hayne, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said in a statement. "We firmly establish the clouds are composed of carbon dioxide — flakes of Martian air — and they are thick enough to result in snowfall accumulation at the surface."

The find means Mars hosts two different kinds of snowfall. In 2008, NASA's Phoenix lander observed water-ice snow — the stuff we're familiar with here on Earth — falling near the Red Planet's north pole,.

Hayne and his team studied data gathered by MRO's Mars Climate Sounder instrument during the Red Planet's southern winter in 2006-2007. This instrument measures brightness in nine different wavelengths of visible and infrared light, allowing scientists to learn key characteristics of the particles and gases in the Martian atmosphere, such as their sizes and concentrations.

The research team examined measurements the Mars Climate Sounder made while looking at clouds — including one behemoth 300 miles (500 kilometers) wide — from directly overhead, and from off to the side. These combined observations clearly revealed dry-ice snow falling through the Red Planet's skies, researchers said.

"One line of evidence for snow is that the carbon-dioxide ice particles in the clouds are large enough to fall to the ground during the lifespan of the clouds," said co-author David Kass, also of JPL. "Another comes from observations when the instrument is pointed toward the horizon, instead of down at the surface."

"The infrared spectra signature of the clouds viewed from this angle is clearly carbon-dioxide ice particles, and they extend to the surface," Kass added. "By observing this way, the Mars Climate Sounder is able to distinguish the particles in the atmosphere from the dry ice on the surface."

Astronomers still aren't entirely sure how the dry ice sustaining Mars' south polar cap — the only place where frozen carbon dioxide exists year-round on the planet's surface — is deposited. It could come from snowfall, or the stuff may freeze out of the air at ground level, researchers said.

"The finding of snowfall could mean that the type of deposition — snow or frost — is somehow linked to the year-to-year preservation of the residual cap," Hayne said.

Dry ice requires temperatures of about minus 193 degrees Fahrenheit (minus 125 Celsius) to fall, reinforcing just how cold the Martian surface is.

The study will be published in an upcoming issue of the Journal of Geophysical Research. Hayne performed the research while a postdoc at Caltech in Pasadena.

SOURCE

Carbon-dioxide traps heat -- mars must be extremely cold for carbon-dioxide to exist in solid form. There's frozen hydrogen too; so there's water on mars. But the water is frozen beneath the surface. If any form of life ever existed on planet mars, life should still exist, at least in bacterial form.

Exactly, only in bacterial form. The temperature there is -125C lol. I'm sure life existed at one point. It's super interesting. More will be revealed in time, I'm sure.

ogugua88: Exactly, only in bacterial form. The temperature there is -125C lol. I'm sure life existed at one point. It's super interesting. More will be revealed in time, I'm sure.

Why bother much about life that is in bacterial form and less significant while there are more issues that threatens life in human form here on Earth?. Drastic weather change(global warming) is a major concern to Earth's existence, i think scientist shouldn't waste much energy on Mar's findings which is rather less inhabitable and channel such time and effort unto re-inventing Earth.

masterpiecer:

Why bother much about life that is in bacterial form and less significant while there are more issues that threatens life in human form here on Earth?. Drastic weather change(global warming) is a major concern to Earth's existence, i think scientist shouldn't waste much energy on Mar's findings which is rather less inhabitable and channel such time and effort unto re-inventing Earth.

Solutions to local problems are mostly gotten from exploring our environment without limits.It helps u know the past so that u can predict the future.

Without space exploration there won't be GSM phones,satelite TVs, GPS car tracking,Osama may not be caught,Sunamese,hurricanes,size of forest fires,sizes of desert encroachment,sizes of jungles,volumes of rivers,weather changes,bird migration,ocean currents and lots of evironmental parameters and changes won't be seen,or at least be seen in good time and estimated.

Do not think that they are whiling away time and burning money. No ! Those very remoute areas affect ur daily life on earth.If bacteria are found in mars,that means life is either beggining in mars or ending.That will help u understand ur fate and position as a human.