Mars Reconnaissance Orbiter Robotic News
September 12, 2012 20:46:6
NASA Orbiter Observations Point to 'Dry Ice' Snowfall on Mars
By Source: JPL NASA

PASADENA, Calif. -- NASA's Mars Reconnaissance Orbiter data have given scientists the clearest evidence yet of carbon-dioxide snowfalls on Mars. This reveals the only known example of carbon-dioxide snow falling anywhere in our solar system.

Frozen carbon dioxide, better known as "dry ice," requires temperatures of about minus 193 degrees Fahrenheit (minus 125 Celsius), which is much colder than needed for freezing water. Carbon-dioxide snow reminds scientists that although some parts of Mars may look quite Earth-like, the Red Planet is very different. The report is being published in the Journal of Geophysical Research.

"These are the first definitive detections of carbon-dioxide snow clouds," said the report's lead author, Paul Hayne of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "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 snowfalls occurred from clouds around the Red Planet's south pole in winter. The presence of carbon-dioxide ice in Mars' seasonal and residual southern polar caps has been known for decades. Also, NASA's Phoenix Lander mission in 2008 observed falling water-ice snow on northern Mars.

Hayne and six co-authors analyzed data gained by looking at clouds straight overhead and sideways with the Mars Climate Sounder, one of six instruments on the Mars Reconnaissance Orbiter. This instrument records brightness in nine wavebands of visible and infrared light as a way to examine particles and gases in the Martian atmosphere. The analysis was conducted while Hayne was a post-doctoral fellow at the California Institute of Technology in Pasadena.

The data provide information about temperatures, particle sizes and their concentrations. The new analysis is based on data from observations in the south polar region during southern Mars winter in 2006-2007, identifying a tall carbon-dioxide cloud about 300 miles (500 kilometers) in diameter persisting over the pole and smaller, shorter-lived, lower-altitude carbon dioxide ice clouds at latitudes from 70 to 80 degrees south.

"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," co-author David Kass of JPL said. "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. By observing this way, the Mars Climate Sounder is able to distinguish the particles in the atmosphere from the dry ice on the surface."

Mars' south polar residual ice cap is the only place on the Red Planet where frozen carbon dioxide persists on the surface year-round. Just how the carbon dioxide from Mars' atmosphere gets deposited has been in question. It is unclear whether it occurs as snow or by freezing out at ground level as frost. These results show snowfall is especially vigorous on top of the residual cap.

"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.

 
 Observations by NASA's Mars Reconnaissance Orbiter have detected carbon-dioxide snow clouds on Mars and evidence of carbon-dioxide snow falling to the surface. Image credit: NASA/JPL-Caltech

 JPL, a division of the California Institute of Technology in Pasadena, provided the Mars Climate Sounder instrument and manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate in Washington

More Interactive Photography
Gale Crator InterActive First look crisp look around Gale Crator This 360-degree, full-resolution panorama from NASA's Curiosity rover shows the area all around...
Endeavour nose gear in OPF InterActive Endeavour nose gear in OPF This was shot from forward and underneath Space Shuttle Endeavour in the Orbiter Processing...
Endeavor engine compartment InterActive Endeavor engine compartment View into the Space Shuttle's engine compartment with the three main engines removed.
Endeavor engine compartment InterActive Endeavor engine compartment View into the Space Shuttle's engine compartment with the three main engines removed.
Endeavour Cargo Bay InterActive Endeavour Cargo Bay This image was shot from the forward end of Space Shuttle Endeavour's cargo ba as it sits in...
Interior view of the Space Shuttle Endeavour forward flight deck. InterActive Interior view of the Space Shuttle Endeavour forward flight deck. Interior view of the Space Shuttle Endeavour aft flight deck.
Endeavour Forward Flight Deck InterActive Endeavour Forward Flight Deck Interior view of the Space Shuttle Endeavour forward flight deck.
Atlas V with Mars Science Laboratory payload InterActive Atlas V with Mars Science Laboratory payload The rover Curiosity will carry the biggest, most advanced suite of instruments for scientific...
Curiosity rover InterActive Curiosity rover NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or...
Curiosity rover InterActive Curiosity rover NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or...
Gravity Recovery and Interior Laboratory InterActive GRAIL The Gravity Recovery and Interior Laboratory mission's primary science objectives will be to...
Atlas V AV-029 InterActive Atlas V AV-029 ULA Atlas V number AV-029 reaches launch pad on August 4th, 2011. In less than 1 day this Atlas...
Atlas V up close InterActive Atlas V up close Get to know the Atlas V up close. Explore the rivets in this 74.62 megapixel image of the Atlas...
JUNO Atlas V InterActive JUNO Atlas V ULA Atlas V with the JUNO probe sitting atop at Cape Canaveral Air Force Station is ready for...
Atlantis at wheels stop on runway 15 InterActive Atlantis on runway Space Shuttle Atlantis returned to Earth in the predawn hours of July 21st, 2011. Marking the...
Atlantis at wheels stop on runway 15 InterActive Atlantis at wheels stop on runway 15 Space Shuttle Atlantis returned to Earth in the predawn hours of July 21st, 2011. Marking the...
Atlantis and tower InterActive Atlantis and tower Space shuttle Atlantis waits to receive payload for the final space shuttle mission STS-135,...
Atlantis payload preparations InterActive Atlantis payload preparations Space shuttle Atlantis at pad 39A. The payload canister can be seen lifted in to position to...
Walk with the astronauts InterActive Walk with the astronauts A view of the 195ft level of the fixed service structure. This where the astronauts arrive at...
Last Space Shuttle prepares for launch InterActive Last Space Shuttle prepares for launch A close in look at space shuttle Atlantis on June 17th. Launch preparations are on going for...
The last space shuttle to be on the launch pad InterActive The last space shuttle to be on the launch pad Space shuttle Atlantis, the last space shuttle to flight begins launch prepartions at pad 39A...
Last space shuttle arrives at launch pad InterActive Last space shuttle arrives at launch pad Space shuttle Atlantis is seen here from the top of the rotating service structure the moring...
The last space shuttle has left the building InterActive The last space shuttle has left the building Space shuttle Atlantis rolls out of the Vehicle Assembly Building for the last time on the...
Space Shuttle Atlantis prepared to rollout to pad   InterActive Space Shuttle Atlantis prepared to rollout to pad Space shuttle Atlantis complete with the solid rocket boosters and external tank that will...
HiRes Atlantis hanging in VAB InterActive HiRes Atlantis hanging in VAB HiRes image of Space Shuttle Atlantis hanging in the Vehical Assembly Building. This shot was...
Atlantis vertical from VAB Level 5 InterActive Atlantis vertical from VAB Level 5 Space Shuttle Atlantis after being lifted into the verticle position before being mated to the...
Atlantis vertical InterActive Atlantis vertical Space Shuttle Atlantis hangs vertical before removing the rear hoist and lifting it for the...
Atlantis rolling vertical InterActive Atlantis rolling vertical Here Space Shuttle Atlantis is almost vertical being positioned to soon be mated to the...
Atlantis hanging in VAB InterActive Atlantis hanging in VAB Space Shuttle Atlantis is seen here hanging about 10 feet above the VAB floor. It has justed...
Endeavour at night InterActive Endeavour at night Space shuttle Endeavour seen here at night as launch preparation continue for the first launch...
Atlantis rolling over to VAB for final mission InterActive Atlantis rolling over to VAB for final mission Space Shuttle Atlantis rolling over the VAB for the last time. Atlantis is scheduled to be the...
Atlantis outside VAB for employee photos InterActive Atlantis outside VAB for employee photos Space shuttle Atlantis, the last space shuttle, pauses during rollover from the OPF to the VAB...
Hi Resolution image of the last space shuttle InterActive Hi Resolution image of the last space shuttle Hi Resolution composit image of the last space shuttle, Atlantis, as it sits atop the transport...
Atlantis in the VAB InterActive Atlantis in the VAB Nice 360 degree view of the VAB with Atlantis being preped for the Lift and Mate procedure
Atlantis on the sled in VAB InterActive Atlantis on the sled in VAB Explore the VAB with Space Shuttle Atlantis on the sled after rollover to the VAB jst before...
Atlantis being attached to sling InterActive Atlantis being attached to sling Full 360 degree panorama from inside the VAB as Space Shuttle Atlantis is attached to the sling...
Endeavour after RSS retraction InterActive Endeavour after RSS retraction Hi-Res image of Space Shuttle Endeavour on the launch pad 39A minutes after the RSS was...
The Mound STS-134 4/29 Attempt InterActive The Mound STS-134 4/29 Attempt This a 360 degree panorama from the mound of the KSC media center. This was the scence about an...
Alpha Magnetic Spectrometer (AMS) InterActive Alpha Magnetic Spectrometer (AMS) The Alpha Magnetic Spectrometer-2, a particle physics detector designed to search for various...
AMS in the SSPF InterActive AMS in the SSPF The Alpha Magnetic Spectrometer-2, a particle physics detector designed to search for various...
Here is Space Shuttle Endeavour just after sunrise InterActive Here is Space Shuttle Endeavour just after sunrise Here is Space Shuttle Endeavour just after sunrise the morning it arrived from the VAB. How...
Endeavour in the VAB InterActive Endeavour in the VAB Space Shuttle Endeavour sitting stacked and ready atop the crawler to rollout the launch pad.
Endeavour in the VAB InterActive Endeavour in the VAB Space Shuttle Endeavour sitting stacked and ready atop the crawler to rollout the launch pad.
Space Shuttle Discovery final towover InterActive Space Shuttle Discovery final towover View of Space Shuttle Discovery 4 hours after returning to Earth for the last time. Discovery...
Space Shuttle Discovery Final Launch InterActive Space Shuttle Discovery Final Launch This a 360 degree panorama taken 3 mile from the launch pad capturing the final lift off of...
Space shuttle Discovery final launch InterActive Space shuttle Discovery final launch This a 360 degree panorama taken 3 mile from the launch pad capturing the final lift off of...
Discovery at Night InterActive Discovery at Night This a panorama of Space Shuttle Discovery shortly after RSS retraction on 11/3/2010 preparing...
GRIP DC-8 Panorama InterActive GRIP DC-8 Panorama Interior of forward section of NASA GRIP aircraft while configured for studding hurricane...
GRIP DC-8 Interior InterActive GRIP DC-8 Interior Interior of forward section of NASA GRIP aircraft while configured for studding hurricane...
NASA GRIP DC-8 InterActive NASA GRIP DC-8 The NASA DC-8 is a four-engine jet transport that has been highly modified to support the...
Endeavour on pad InterActive Endeavour ready for launch HiRes image of Endeavour at Pad 39A
AMS-2 Antimatter Telescope InterActive AMS-2 Antimatter Telescope Explore the SSPF and ESA's Antimatter Telescope. 360 rotating,zoomable Panorama!
Spectacular ultra hi-rez interactive shot of the Space Shuttle Endeavour on the launch pad for the last time InterActive Explore LC-39A !! Spectacular ultra hi-rez interactive shot of the Space Shuttle Endeavour on the launch pad for...