Martian Landscaping: Spacecraft eyes evidence of a frozen sea

Science News ^ | 3.5.05

[ambrose]

March 5, 2005; Vol. 167, No. 10 , p. 149 Martian Landscaping: Spacecraft eyes evidence of a frozen sea

Ron Cowen

A flat region near the Red Planet's equator may hold a frozen ocean that was once as deep and big as the North Sea. The region's relatively craterless facade suggests that water gushed to the surface and froze recently, raising the possibility that life might exist today on or just beneath the surface, says Mars Express researcher John Murray. Last week, his team reported its analysis of images that were taken by the orbiting Mars Express spacecraft.

In this region, "you've had water above freezing beneath the face of Mars for thousands of millions of years," says Murray, a volcanologist and planetary scientist at the Open University in Milton Keynes, England. "This is the place to go look for life," he adds.

His group, which examined images taken with the spacecraft's High Resolution Stereo Camera, reported its findings on Feb. 25 at a European Space Agency briefing in Noordwijk, the Netherlands. The team will present further details in the March 17 Nature.

Other researchers caution that the flat region, known as Elysium Planitia, might have been sculpted by flowing lava or a mixture of lava and water. This set of scenarios is far less amenable to the presence of life on Mars.

But Murray maintains that water, not lava, shaped Elysium Planitia. Solidified lava and ice would leave different marks on the surface, he says. For every criterion that he has applied, he told Science News, "the Elysium features correspond to the morphology of ice."

The few craters poking above the surface, for example, suggest a frozen sea, Murray says. The craters appear as if they had once been filled with liquid to 45 meters but that the level later dropped to about 30 m. Water can disappear by evaporation or by seeping into the ground, but lava filling a crater would remain trapped there, he argues.

Moreover, "the surface [of Elysium Planitia] is flat to a remarkable degree over more than 50 kilometers, the same as a sea surface where the tide is coming in," Murray says.

Exposed ice at the Martian equator would rapidly sublimate. Murray's team suggests that a layer of ash or dust 1 to 20 m thick has blanketed the ice and preserved it. Such a layer could explain why the spectrometers on several Mars orbiters haven't detected the signature of ice, leading scientists to conclude that the planet has been dry for billions of years.

Jim Rice of Arizona State University in Tempe, who previously suggested that water played a role in forming features at Elysium Planitia, says that a thick deposit of ash on top of a frozen sea seems far-fetched. He argues that a complex interplay of lava and water is more likely to have shaped the area and that the ice that might once have been there vanished long ago.

Images taken by the Mars Reconnaissance Orbiter, slated for launch this summer, could add data to the debate, but a lander may be needed to settle the geological story behind Elysium Planitia, Rice says.

[Excuse_My_Bellicosity]

Unusual Plates on Mars

Credit: G. Neukum (FU Berlin) et al., Mars Express, DLR, ESA

Explanation: What are those unusual plates on Mars? A leading current interpretation holds that they are blocks of ice floating on a recently frozen sea covered by dust. The unusual plates were photographed recently by the European Space Agency's Mars Express spacecraft currently orbiting Mars. Oddly, the region lies near the Martian equator and not near either of Mars' frozen polar caps. Without being covered by dust, any water or ice near away from the poles would quickly evaporate right into the atmosphere. Evidence that the above-imaged plates really are dust-covered water-ice includes a similarity in appearance to ice blocks off Earth's Antarctica, nearby surface fractures from which underground water could have flowed, and the shallow depth of the craters indicating that something is filling them in. If correct, the low abundance of craters indicates that water may have flowed on Mars as recently as five million years ago.

Link here: http://antwrp.gsfc.nasa.gov/apod/ap050228.html

[Arkie2]

If they're right it's one more piece of the puzzle in place for a sustainable Martian colony. Looks like a good target for the next robot probe.

[DixieOklahoma]

All your planets are belong to us

Hey, where's the typical 1860's black and white photographs that Nasa usually uses when taking important pictures of the surface of another planet?

Maybe they updated to the 1970's?

[Excuse_My_Bellicosity]

Yep, having water there sure would help. You'd have to bring along an apparatus to purify the water that you'd find on Mars, but it sure beats having to carry tons of water with you!

[Excuse_My_Bellicosity]

No joke, the pics coming back look really good. Take a look at this one here:

Explanation: First imaged by the Mariner 9 spacecraft, Valles Marineris, the grand canyon of Mars, is a system of enormous depressions or chasmas that stretch some 4,000 kilometers along the Martian equator. Looking north over the canyon's central regions, dark Melas Chasma lies in the foreground of this spectacular perspective view. Behind it are Candor Chasma and the steep walls of Ophir Chasma near the horizon. Faulting, surface collapse and landslides are seen to be part of the complex geologic history of these dramatic features, with layered deposits also found within the canyon system. Recorded in 2004, the image represents data from the High Resolution Stereo Camera (HRSC) on board ESA's Mars Express spacecraft. Melas, Candor and Ophir are about 200 kilometers wide and 5 to 7 kilometers deep.

You can get a really good hi-rez pic if you copy the following URL into your web browser: http://antwrp.gsfc.nasa.gov/apod/image/0502/chasma_marsExpress_f50.jpg

[PoorMuttly]

Bet they'll ruin the fishing.

[kennedy]

Looks like a nice spot for a hotel resort. Maybe my great-grandkids can stay there.

[ASA Vet]

Link to the really big photo

Don't try it unless you have a high speed connection.

[Excuse_My_Bellicosity]

Yep, I provided this address at the bottom of my other post. Good call, don't download it unless you have DSL or higher. That landscape looks like my part of the country at sunset. Pretty neat. The high-rez shows some really amazing detail.

[shaggy eel]

Bet they'll ruin the fishing.

,,, bet the fishing's just fine. If all else fails, build a casino and they'll come, shuttle by shuttle.

[SunkenCiv]

Blast from the Past for the space lists? Perhaps it has already appeared.

related:

Red Planet's Ancient Equator Located
Scientific American (online) | April 20, 2005 | Sarah Graham
Posted on 04/24/2005 8:18:25 PM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1390424/posts

[KevinDavis]

[COBOL2Java]

Looks like the floor of my shower stall...

[COBOL2Java]

Here it is shrunk down a bit:

[Cvengr]

Ohmigosh,....those aren't plates,...they're giant eyesockets!