SpaceJibe

June 18, 2009

University of Colorado team finds definitive evidence for ancient lake on Mars

Filed under: Extraterrestrial Life, Inner Solar System, Life, Mars, Space Exploration — bferrari @ 12:56 pm

Shalbatana Lake - Mars (G. Di Achille, University of Colorado)

Shalbatana Lake - Mars (G. Di Achille, University of Colorado)

First unambiguous evidence for shorelines on the surface of Mars, say researchers

A University of Colorado at Boulder research team has discovered the first definitive evidence of shorelines on Mars, an indication of a deep, ancient lake there and a finding with implications for the discovery of past life on the Red Planet.

Estimated to be more than 3 billion years old, the lake appears to have covered as much as 80 square miles and was up to 1,500 feet deep — roughly the equivalent of Lake Champlain bordering the United States and Canada, said CU-Boulder Research Associate Gaetano Di Achille, who led the study. The shoreline evidence, found along a broad delta, included a series of alternating ridges and troughs thought to be surviving remnants of beach deposits.

“This is the first unambiguous evidence of shorelines on the surface of Mars,” said Di Achille. “The identification of the shorelines and accompanying geological evidence allows us to calculate the size and volume of the lake, which appears to have formed about 3.4 billion years ago.”

A paper on the subject by Di Achille, CU-Boulder Assistant Professor Brian Hynek and CU-Boulder Research Associate Mindi Searls, all of the Laboratory for Atmospheric and Space Physics, has been published online in Geophysical Research Letters, a publication of the American Geophysical Union.

Images used for the study were taken by a high-powered camera known as the High Resolution Imaging Science Experiment, or HiRISE. Riding on NASA’s Mars Reconnaissance Orbiter, HiRISE can resolve features on the surface down to one meter in size from its orbit 200 miles above Mars.

An analysis of the HiRISE images indicate that water carved a 30-mile-long canyon that opened up into a valley, depositing sediment that formed a large delta. This delta and others surrounding the basin imply the existence of a large, long-lived lake, said Hynek, also an assistant professor in CU-Boulder’s geological sciences department. The lake bed is located within a much larger valley known as the Shalbatana Vallis.

“Finding shorelines is a Holy Grail of sorts to us,” said Hynek.

In addition, the evidence shows the lake existed during a time when Mars is generally believed to have been cold and dry, which is at odds with current theories proposed by many planetary scientists, he said. “Not only does this research prove there was a long-lived lake system on Mars, but we can see that the lake formed after the warm, wet period is thought to have dissipated.”

Planetary scientists think the oldest surfaces on Mars formed during the wet and warm Noachan epoch from about 4.1 billion to 3.7 billion years ago that featured a bombardment of large meteors and extensive flooding. The newly discovered lake is believed to have formed during the Hesperian epoch and postdates the end of the warm and wet period on Mars by 300 million years, according to the study.

The deltas adjacent to the lake are of high interest to planetary scientists because deltas on Earth rapidly bury organic carbon and other biomarkers of life, according to Hynek. Most astrobiologists believe any present indications of life on Mars will be discovered in the form of subterranean microorganisms.

But in the past, lakes on Mars would have provided cozy surface habitats rich in nutrients for such microbes, Hynek said.

The retreat of the lake apparently was rapid enough to prevent the formation of additional, lower shorelines, said Di Achille. The lake probably either evaporated or froze over with the ice slowly turning to water vapor and disappearing during a period of abrupt climate change, according to the study.

Di Achille said the newly discovered pristine lake bed and delta deposits would be would be a prime target for a future landing mission to Mars in search of evidence of past life.

“On Earth, deltas and lakes are excellent collectors and preservers of signs of past life,” said Di Achille. “If life ever arose on Mars, deltas may be the key to unlocking Mars’ biological past.”

Source

June 12, 2009

Boy Hit By Meteorite Travelling At 30,000mph

Filed under: Asteroids, Exoplanets, Wierd — bferrari @ 9:51 pm

10:22am UK, Friday June 12, 2009

A teenager was hit by a meteorite travelling at 30,000mph – and lived to tell the tale.

The meteorite struck Gerrit on the hand, and buried itself in the road

The meteorite struck Gerrit on the hand, and buried itself in the road

Gerrit Blank was on his way to school when he saw a massive fireball heading straight towards him from the sky.

The white-hot meteorite bounced off the schoolboy’s hand and hit the ground so hard it left a foot-long crater in the tarmac – as well as a three-inch scar on his hand.

Gerrit, 14, said: “At first I just saw a large ball of light and then I suddenly felt a pain in my hand.

“Then, a split second after that, there was an enormous bang like a crash of thunder.”

“The noise that came after the flash of light was so loud that my ears were ringing for hours afterwards.

“When it hit me it knocked me flying and then was still going fast enough to bury itself in the road.”

Scientists are now studying the pea-sized meteorite, which crashed to Earth in Essen in Germany.

Chemical tests on the rock have now proved it is from outer space.

Ansgar Korte, director of Germany’s Walter Hohmann Observatory, said: “It’s a real meteorite, therefore it is very valuable to collectors and scientists.”

Chances of being struck by a meteorite are around one in 100 million.

Mr Korte said: “Most meteorites don’t actually make it to ground level because they evaporate in the atmosphere.

“Of those that do get through, about six out of every seven of them land in water.”

There is only one other known case of a human being surviving a direct hit from a meteor.

A grapefruit-sized meteor crashed through the roof of a house in Alabama, in the USA, in 1954.

After smashing through the top of the building, it bounced off furniture and then hit a woman who was asleep at the time.

Source

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