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Loss of obliquity on mars and its consequences toward life

  1. Jan 15, 2012 #1
    I read this very interesting article on physorg about how planetary tilt is essential to life and various things that can diminish axial tilt over time or not give rise to one; things that would make life less probable.

    But I came across this quote that I couldn't help but question the accuracy of its statement.

    "For an opposite case, consider Mars. Hulking Jupiter wreaks havoc with the Red Planet's obliquity, causing it to vary by perhaps as much as 60 degrees over the course of a million years, Heller said. Those disturbances lead to big swings in global temperatures and glacier cover, and on more habitable worlds that sort of climatic chaos could spell the end for life."

    I don't have the required mathematical and scientific knowledge to criticize [for lack of better words] this statement. Could a variance of 60 degrees over the course of a million years cause the end of life [not implying there was, of course]? Is it a constant rate of change?
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  3. Jan 15, 2012 #2

    Simon Bridge

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    Large obliquity would produce extreme seasons ... a lifeform would need to be able to evolve to handle variations like this with enough differentiation to speciate when things change to a more stable situation or to a more variable one. 1million years usually considered a little short for this.

    Imagine Mars went through an Earth-like phase, and developed basic life - it would be hard pressed to get past the simple-cell level before the climate gets ripped apart - either going cold and stable-ish or running to extreme seasonal variations.

    Such cells may go dormant and bloom into life when conditions return ... but for millions of years?

    It's mostly speculation but the odds are against anything evolving planetside even as far as blue-green algae.
  4. Jan 16, 2012 #3


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    Given the different extremes that life has been found in here on Earth, I don't see any reason to think that something like this could wipe out ALL life on Mars unless it simply hadn't had enough time for a good amount of speciation to occur. Whether something like this could keep life from developing at all, I don't know.
  5. Jan 16, 2012 #4

    D H

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    One thing can be said with certainty regarding life on Mars: There is no advanced life on Mars right now.

    Whether life in any form has existed on Mars, ever: We don't know. Whether primitive life still exists in some form: We don't know that, either. Whether a more or less constant obliquity is essential for life: That's yet another "We don't know." There is an ever-present danger of extrapolating from a sample size of one in astrobiology.
  6. Jan 16, 2012 #5

    Simon Bridge

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    We can only talk about how the kinds of life we know about would handle Mars through it's development. On top of which, the author is vague about what is meant by "the end for life" ... could just be thinking about macroscopic organisms like cats and dogs and so on when we have been thinking in terms of global sterilization.

    Getting beyond the "sample size of one" is part of why it is so important to biology to look for life on Mars ... even if it is signs of ancient life.
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