Mars theory cites episodes of wet asteroids

Seatle Times ^ | December 06, 2002 | Paul Recer

[farmfriend]

Mars theory cites episodes of wet asteroids

By Paul Recer
The Associated Press

WASHINGTON — Mars never had oceans as some researchers claim, but instead is a cold, dry planet that was pounded by water-bearing asteroids and showered with scalding rain that carved vast gullies and valleys, a new study claims.

The study, reported this week in the journal Science, sheds new light on a continuing debate by Mars researchers about how much water was on Mars, where it went and how it formed the planet's intricate pattern of canyons, riverbeds and deltas.

Using Mars photos and computer simulations, researchers at the University of Colorado at Boulder concluded that immense asteroids pounded Mars some 3.6 billion years ago, bringing vast quantities of water to the young planet and releasing powerful shock waves of heat that melted existing underground ice deposits.

Owen Toon, senior author of the study, said at least 25 craters on Mars were gouged out by asteroids 60 to 150 miles in diameter. The impact of such large space rocks would have propelled into the atmosphere millions of tons of superheated rock vapor and melted ice. It also would have unleashed a blast wave heated to more than 4,000 degrees and blanketed the entire planet with heated rock several hundred feet thick.

"The atmosphere would be hotter than a self-cleaning oven," Toon said. "When the water was released from the atmosphere, it would fall as scalding rain."

The blanket of hot rocks "would be a global thing, causing rivers to form anywhere. The ice would be melting all over the planet," he said.

Based on erosion, Mars researchers estimated that more than 150 feet of water would flow in some areas after a major impact, carving the riverine features. By some calculations, they said, there could have been many decades with rainfall of 6 feet per year.

Between impacts, Toon said, Mars would cool, turning again into a dry, chilled planet with water present only as subsurface ice.

"We believe these events caused short periods of a warm and wet climate, but overall, we think Mars has been cold and dry for the majority of its history," co-author Teresa Segura said.

Because the moist and warm periods were short, Segura said, conditions were not favorable for life to evolve on the planet's surface.

Peter Smith, a University of Arizona planetary scientist, said that if warmth and liquid water were available on Mars only episodically, "then you have a pretty gloomy picture for life."

But he said there were other forces, particularly volcanic action, that may have created subsurface pools of water where microscopic life could have lived.

"In my opinion, they haven't closed the book on the prospects for the evolution of life on Mars," Smith said.

Ronald Greeley, a planetary researcher at Arizona State University, said the study by Toon, Segura and others "could account for many of the apparently water-eroded features."

Still, Greeley said the study "doesn't put a nail in the coffin" for evolution of life on Mars. Like Smith, he said hydrothermal systems powered by volcanic action and subsurface brine pools could exist and would be favorable for the evolution of life.

[farmfriend]

ping

[farmfriend]

ping

[Fish out of Water]

Shouldn't that be the Seattle times?

[farmfriend]

Hey, you should see the errors I catch in time.

[Fish out of Water]

:^)
Bump

[gcruse]

.. pounded by water-bearing asteroids and showered with scalding rain that carved vast gullies and valleys, a new study claims.

...  immense asteroids pounded Mars some 3.6 billion years ago, bringing vast quantities of water to the young planet and releasing powerful shock waves of heat that melted existing underground ice deposits.

1. Where did the existing underground ice come from?
2.  Comets are dirty snowballs (water).
3.  Asteroids are rocks--how could they get wet?
4.  Could Mars have been pounded by comets instead?

[Nitro]

"The atmosphere would be hotter than a self-cleaning oven,"

My oven goes to 900 degrees for cleaning!!

On a lighter note we are currently at a 13/14 Billion age of the Universe based on the latest Hubble sightings!

Let's face it, for all we know there are billions of things we don't!!

Like who is gonna get whacked in the season finale of the Soprano's!!

[null and void]

11 In the six hundredth year of Noah's life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened.
12 And the rain was upon the earth forty days and forty nights.

[farmfriend]

You are talking to a lobbyist who had Isaiah 55:11 hung up in her office.

[null and void]

An ideal quote for a lobbyist...

[farmfriend]

I take that back, I had included verse 10 as well. Even better since I was lobbying for the Grange, founded in 1867, it's the oldest general farm and public policy organization in the US.

[SunkenCiv]

Note: this topic is from 12/07/2002. Thanks farmfriend.

[snip] Mars never had oceans as some researchers claim, but instead is a cold, dry planet that was pounded by water-bearing asteroids and showered with scalding rain that carved vast gullies and valleys... immense asteroids pounded Mars some 3.6 billion years ago, bringing vast quantities of water to the young planet and releasing powerful shock waves of heat that melted existing underground ice deposits... at least 25 craters on Mars were gouged out by asteroids 60 to 150 miles in diameter. The impact of such large space rocks would have propelled into the atmosphere millions of tons of superheated rock vapor and melted ice. It also would have unleashed a blast wave heated to more than 4,000 degrees and blanketed the entire planet with heated rock several hundred feet thick. [/snip]

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