HiRISE Sees Signs of an Unearthly Spring on Mars

Mar 25, 2009 By Lori Stiles
Solid carbon dioxide, commonly known as dry ice, thaws directly to gas and forms starburst patterns under the seasonal carbon dioxide ice caps when spring comes to Mars' polar regions. This is a small part of a much larger image taken by The University of Arizona-led High Resolution Science Imaging Experiment, or HiRISE. The HiRISE camera is aboard NASA's Mars Reconnaissance Orbiter. (NASA/JPL-Caltech/University of Arizona)

(PhysOrg.com) -- New images from the HiRISE experiment detail patterns of dust carried by gas from beneath the seasonal ice cap.

The Experiment, or , run from The University of Arizona, is seeing signs of on .

The signs are absolutely martian and unearthly.

The HiRISE team today released new high-resolution images of terrain at Mars' south polar region taken last month by their camera aboard NASA's Mars Reconnaissance Orbiter.

The images can be viewed on the HiRISE Website.

"Spring on Mars is quite different from spring on Earth because Mars has not just permanent ice caps, but also seasonal polar caps of , familiar to us on Earth as dry ice," said HiRISE deputy principal investigator Candice J. Hansen-Koharcheck of the NASA Jet Propulsion Laboratory in Pasadena, Calif.

The seasonal polar caps form each winter because carbon dioxide in the atmosphere changes directly to frost, which builds into a dry ice layer over Mars' surface. Dry ice caps can be as much as a meter thick, Hansen-Koharcheck said.

Then, as winter wanes and spring arrives, warmer temperatures thaw solid carbon dioxide directly from ice into gas.

The seasonal thins both from the top and the bottom.

The gas beneath the ice cap can flow in the same places year after year after year, eroding troughs in the surface of the planet. Scientists know that the gas carves troughs into the surface of the planet itself because the troughs are still visible after the caps are gone entirely.

"What happens on Mars, we think, is that as the seasonal ice cap thins from the bottom, gas underneath the cap builds up pressure," Hansen-Koharcheck said. "And where gas under the ice finds a weak spot or a crack, it will flow out of the opening, often carrying a little dust from the surface below."

That pressure buildup beneath the carbon-dioxide ice is a key difference between this process and springtime thawings of on Earth. When warmed, water ice and snowpacks on Earth can melt to liquid and either run off beneath the frozen layer or soak into the ground.

One HiRISE image released today shows fan-shaped deposits of dust that form beautiful starburst patterns. The dust was carried from beneath the seasonal ice cap by jets of carbon dioxide escaping from radial troughs, often called "spiders," because of their shape.

Another HiRISE image released today shows how dust that has been carried to the surface by gas jetting through the ice cap is blown about by prevailing winds before settling in fan-shaped deposits atop the ice cap.

Many jets appear to be active at the same time, according to this picture, because numerous fans are all deposited in the same direction.

Fans at the top of the picture are oriented in one direction, while fans at the bottom are oriented in a different direction. This suggests that as the ice layer thins, a set of gas jets becomes active and dies down, then another set, farther away, becomes active at a later time when there is a different prevailing wind direction, Hansen-Koharcheck said.

She estimated that the ice cap seen in the images is about a half-meter thick.

Mars Reconnaissance Orbiter is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, for the NASA Science Mission Directorate. Lockheed Martin Space Systems, based in Denver, is the prime contractor and built the spacecraft. Ball Aerospace and Technologies Corp., of Boulder, Colo., built the HiRISE camera.

Provided by University of Arizona (news : web)

Explore further: Red moon at night; stargazer's delight

add to favorites email to friend print save as pdf

Related Stories

Martian Polar Layer Erosion Looks Striking

Oct 16, 2008

(PhysOrg.com) -- An odd, solitary hill rising part-way down an eroding slope in Mars' north polar layered terrain may be the remnant of a buried impact crater, suggests a University of Arizona planetary scientist ...

Mars Orbiter Photographs Avalanches

Mar 03, 2008

A NASA spacecraft in orbit around Mars has taken the first ever image of active avalanches near the Red Planet's north pole. The image shows tan clouds billowing away from the foot of a towering slope, where ...

Decoding Mars's cryptic region

Oct 19, 2006

Mars Express's OMEGA instrument has given planetary scientists outstanding new clues to help solve the mystery of Mars's so-called 'cryptic region'.

Dark Pit on Mars' Arsia Mons, with Sunlit Wall

Aug 31, 2007

The High Resolution Imaging Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter has confirmed that a dark pit seen on Mars in an earlier HiRISE image really is a vertical shaft that cuts through ...

Recommended for you

Red moon at night; stargazer's delight

17 hours ago

Monday night's lunar eclipse proved just as delightful as expected to those able to view it. On the East Coast, cloudy skies may have gotten in the way, but at the National Science Foundation's National Optical ...

Meteorites yield clues to Martian early atmosphere

20 hours ago

(Phys.org) —Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published ...

Let's put a sailboat on Titan

23 hours ago

The large moons orbiting the gas giants in our solar system have been getting increasing attention in recent years. Titan, Saturn's largest moon, is the only natural satellite known to house a thick atmosphere. ...

Image: Rosetta's Philae lander snaps a selfie

23 hours ago

Philae is awake… and taking pictures! This image, acquired last night with the lander's CIVA (Comet nucleus Infrared and Visible Analyzer) instrument, shows the left and right solar panels of ESA's well-traveled ...

User comments : 0

More news stories

Cosmologists weigh cosmic filaments and voids

(Phys.org) —Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational ...

Meteorites yield clues to Martian early atmosphere

(Phys.org) —Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published ...

Let's put a sailboat on Titan

The large moons orbiting the gas giants in our solar system have been getting increasing attention in recent years. Titan, Saturn's largest moon, is the only natural satellite known to house a thick atmosphere. ...

Net neutrality balancing act

Researchers in Italy, writing in the International Journal of Technology, Policy and Management have demonstrated that net neutrality benefits content creator and consumers without compromising provider innovation nor pr ...