Space

June 12, 2013

Marks on Martian dunes may reveal tracks of dry ice Sleds

nasa-mars
NASA research indicates† hunks of frozen carbon dioxide — dry ice — may glide down some Martian sand dunes on cushions of gas similar to miniature hovercraft, plowing furrows as they go.

Researchers deduced† this process could explain one enigmatic class of gullies seen on Martian sand dunes by examining images from NASA’s Mars Reconnaissance Orbiter and performing experiments on sand dunes in Utah and California.

“I have always dreamed of going to Mars,” said Serina Diniega, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and lead author of a report published online by the journal Icarus. “Now I dream of snowboarding down a Martian sand dune on a block of dry ice.”

The hillside grooves on Mars, called linear gullies, show relatively constant width – up to a few yards or meters across – with raised banks or levees along the sides. Unlike gullies caused by waterflows on Earth and possibly on Mars, they do not have aprons of debris at the downhill end of the gully. Instead, many have pits at the downhill end.

“In debris flows, you have water carrying sediment downhill, and the material eroded from the top is carried to the bottom and deposited as a fan-shaped apron,” said Diniega. “In the linear gullies, you’re not transporting material. You’re carving out a groove, pushing material to the sides.”

Images from MRO’s High Resolution Imaging Science Experiment camera show sand dunes with linear gullies covered by carbon dioxide frost during the Martian winter. The location of the linear gullies is on dunes that spend the Martian winter covered by carbon dioxide frost. The grooves are formed during early spring, researchers determined by comparing before-and-after images from different seasons. Some images have even caught bright objects in the gullies.

Scientists theorize the bright objects are pieces of dry ice that have broken away from points higher on the slope. According to the new hypothesis, the pits could result from the blocks of dry ice completely sublimating away into carbon-dioxide gas after they have stopped traveling.

“Linear gullies don’t look like gullies on Earth or other gullies on Mars, and this process wouldn’t happen on Earth,” said Diniega. “You don’t get blocks of dry ice on Earth unless you go buy them.”

That is exactly what report co-author Candice Hansen, of the Planetary Science Institute in Tucson, Ariz., did. Hansen has studied other effects of seasonal carbon-dioxide ice on Mars, such as spider-shaped features that result from explosive release of carbon-dioxide gas trapped beneath a sheet of dry ice as the underside of the sheet thaws in spring. She suspected a role for dry ice in forming linear gullies, so she bought some slabs of dry ice at a supermarket and slid them down sand dunes.

That day and in several later experiments, gaseous carbon dioxide from the thawing ice maintained a lubricating layer under the slab and also pushed sand aside into small levees as the slabs glided down even low-angle slopes.

The outdoor tests did not simulate Martian temperature and pressure, but calculations indicate the dry ice would act similarly in early Martian spring where the linear gullies form. Although water ice, too, can sublimate directly to gas under some Martian conditions, it would stay frozen at the temperatures at which these gullies form, the researchers calculate.

“MRO is showing that Mars is a very active planet,” Hansen said. “Some of the processes we see on Mars are like processes on Earth, but this one is in the category of uniquely Martian.”

Hansen also noted the process could be unique to the linear gullies described on Martian sand dunes.

“There are a variety of different types of features on Mars that sometimes get lumped together as ‘gullies,’ but they are formed by different processes,” she said. “Just because this dry ice hypothesis looks like a good explanation for one type doesn’t mean it applies to others.”

The University of Arizona Lunar and Planetary Laboratory operates the HiRISE camera, which was built by Ball Aerospace & Technologies Corp. of Boulder, Colo. JPL manages MRO for NASA’s Science Mission Directorate in Washington. Lockheed Martin Space Systems of Denver built the orbiter.




All of this week's top headlines to your email every Friday.


 
 

 
Images courtesy of NASA/JHU-APL/SwRI

NASA’s New Horizons spacecraft stays course to Pluto

Images courtesy of NASA/JHU-APL/SwRI These images show the difference between two sets of 48 combined 10-second exposures with New Horizons’ Long Range Reconnaissance Imager (LORRI) camera, taken at 8:40 UTC and 10:25 UTC...
 
 
Lockheed Martin photograph

Fourth Lockheed Martin-built MUOS secure comm satellite shipped

Lockheed Martin photograph On June 28, MUOS-4, the next satellite scheduled to join the U.S. Navy’s Mobile User Objective System secure communications network, shipped to Cape Canaveral from Lockheed Martin’s satellite manu...
 
 
Photograph courtesy of NASA/CXC/U. Wisconsin/S. Heinz

NASA’s Chandra captures x-ray echoes pinpointing distant neutron star

Photograph courtesy of NASA/CXC/U. Wisconsin/S. Heinz A light echo in X-rays detected by NASA’s Chandra X-ray Observatory has provided a rare opportunity to precisely measure the distance to an object on the other side of the...
 

 

Veteran NASA spacecraft nears 60,000th lap around Mars

NASA’s Mars Odyssey spacecraft will reach a major milestone June 23, when it completes its 60,000th orbit since arriving at the Red Planet in 2001. Named after the bestselling novel “2001: A Space Odyssey” by Arthur C. Clarke, Odyssey began orbiting Mars almost 14 years ago, on Oct. 23, 2001. On Dec. 15, 2010, it...
 
 
nasa-study

NASA selects six wild ideas in aviation for further study

NASA has selected six proposals to study transformative ideas that might expand what’s possible in aviation, shifting the boundary between fantastic and futuristic. During a day-long meeting in April, 17 teams pitched the...
 
 
NASA photograph

NASA signs agreement with Space Florida to operate historic landing facility

NASA photograph This aerial photo of the runway at the KSC Shuttle Landing Facility looks north. Longer and wider than most commercial runways, it is 15,000 feet long, with 1,000-foot paved overruns on each end, and 300 feet wi...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>