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Palomar

Member

From: USA

Registered: 2002-05-30

Posts: 9,734

Re: Mars Floods & Meteoritic Impacts

*This is from space.com's "Astronotes."  It's in updated, columnar format so must copy and paste:

May 9

Mars Flooding Tied to Meteoritic Impacts

Catastrophic floods that formed channels visible on Mars today might have been the result of meteoritic impacts that struck the red planet early in its history. Those slam dunks on Mars, could have been just that – impactors that repeatedly caused liquefaction and sparked violent eruptions of martian groundwater.

This notion comes from Chi-yuen Wang, Michael Manga, and Alex Wong of the Department of Earth and Planetary Science at the University of California in Berkeley, California. Their work, “Floods on Mars released from groundwater by impact,” is carried in the June issue of Icarus, a scientific journal that spotlights new planetary science research.

Here on Earth, the researchers note, large earthquakes commonly cause saturated soils to liquefy and streamflow to increase. And when saturated soils lose their shear resistance, they become fluid-like, and are ejected to the surface, causing lateral spreading of the ground and a breakdown of foundations that support buildings.

Heavy meteoritic bombardment on the early Mars formed a thick layer of dust, regolith and ejecta. Given the prospect that loads of water was present on the early Mars, a saturated aquifer of global extent may have been present beneath a few miles of frozen ground.

The team points to impacts on Mars that created craters with diameters of 62 miles (100 kilometers) or greater, suggesting that these strikes may have caused global occurrence of liquefaction and streamflow. Liquefaction can release water at great distances from the impact site, they explain.

To support their hypothesis, the team has studied streamflow that generally occurs after earthquakes, as well as possible liquefaction-induced debris-flow deposits tied to craters here on Earth, such as the Oasis crater in Lybia and the Chicxulub crater in Mexico.

The geologic record on Mars appears better preserved than on Earth. And given the lineup of planned Mars orbiters, rovers and lander missions in the future, the researchers conclude it will be just a matter of time before sufficient geologic evidence is accumulated to test their idea.

                                                 - Leonard David

--Cindy

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SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,832

Re: Mars Floods & Meteoritic Impacts

I wonder if the meteor impacts occured around the same time as those on Earths? Especially if these line up with mass extinctions here on earth.

Shaun Barrett

Member

From: Cairns, Queensland, Australia

Registered: 2001-12-28

Posts: 2,843

Re: Mars Floods & Meteoritic Impacts

Interesting article.
    The important words in it for me, are the words "Catastrophic floods that formed channels .. ".
    I'm always trying to tie together different lines of research about Mars in my mind's eye - trying to make a sensible coherent picture of Martian history. (Not an easy task for anybody, least of all me, so you and NASA won't be surprised to learn I haven't really succeeded yet!       )

    But what I'm attempting to do is reconcile the existence of dendritic drainage systems with the major outflow channels. In another thread, I've commented on the research of French scientists, who maintain that widespread drainage systems, consistent with precipitation, indicate rain may have been falling on Mars up until about 3 billion years ago.
    Alongside this information is the hypothesis raised in this thread that impact events caused the extensive melting of underground water-ice deposits, resulting in the explosive release of huge quantities of water onto the Martian surface.

    I suppose there are two ways of looking at this juxtaposition of ideas. They could be separate processes that happened to occur in broadly the same period of time, or one process may in fact be dependent upon the other.

    If Mars had a thicker atmosphere and a warmer climate during its first billion or one-and-a-half billion years, one can imagine seas and evaporation and rainfall rather similar to our familiar terrestrial scene. This situation would have had the added energy input of major impacts, which may have helped to prolong the warm early epoch and maintain the generally balmy environment. (An alternative way of looking at this is to see the impacts as blasting atmosheric gases into space and so ultimately accelerating the cooling of the planet.)
    On the other hand, we can see another possibility. Mars may have been essentially a frozen world, almost from the outset. Major impacts, rather than adding energy to an already warm environment, may have been virtually the only source of warmth other than sporadic volcanism. In this case, any rainfall, which the French scientists believe they have evidence for, would have arisen only because of the intermittent and violent vaporisation of underground ice by impactors.

    Which of the above hypothetical histories actually occurred, may have serious consequences for the possible development of life on early Mars. The 'thick, warm, wet atmosphere' case obviously holds out greater hope for the establishment of a biosphere than the 'frozen waste pounded by impactors' case.

    I'm inclined to think the former case is more likely because of the compelling evidence that the northern lowlands of Mars were probably the bed of an extensive sea or ocean, and because of the evidence for long-term standing bodies of water in the highlands, like Lake Ma'adim.

    Does anyone have any comments or ideas they'd like to add about any of this?  ???   

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