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The Origin and Evolution of Life on Earth

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And could Mars have/had life? Much has been learned from orbiters/rovers that are active today Orbiters: Mars Reconnaissance Orbiter Mars Express Rovers: ... – PowerPoint PPT presentation

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Title: The Origin and Evolution of Life on Earth


1
Happy Halloween!
2
Homework 6 Due 600 pm today
Exam 2 on Wednesday
3
  • Could Mars once have been warm and soggy?

And could Mars have/had life?
4
Much has been learned from orbiters/rovers that
are active today
Orbiters Mars Reconnaissance Orbiter Mars
Express Rovers Spirit Opportunity
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7
Early Mars was similar to Earth
8
Evidence of past water flows
9
Viking Orbiter image
  • The current thin, cold atmosphere prohibits
    liquid water from being stable on the surface.
  • However, there is ample evidence for past water
  • 3 flavors of flowing surface water
  • Valley Networks (really old)
  • Outflow Channels (pretty old)
  • Gullies (really young)

MOLA topography
500 km
10
  • Outflow Channels
  • Formed from catastrophic release of groundwater
    in mid to late Martian history.

11
older, degraded channel system
different flow paths
12
Orbital photos from Mars Express show features
similar to ice patterns seen in Antarctica dust
covered frozen sea?
13
Sedimentary rocks
14
Main evidence for a warm and wet ancient Mars
  • Valley networks
  • Widespread highland erosion (up to a km of crust
    lost)
  • Chemically weathered components of the crust
  • Mars Exploration Rovers show clear signs of
    groundwater interaction and possible signs of
    standing bodies of water

15
Did the Northern Lowlands Once Contain an Ocean?
Northern plains
Northern plains
Tharsis
Valles Marineris
It is quite possible!
16
Evidence of current water flows
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18
  • Gullies

Martian gullies are the best evidence for liquid
water on Mars today. These fresh-cut features
are found on the inner walls of some craters and
the old runoff channels. For water to produce
these features, it must have been released in a
torrent, for a slow trickle will not
suffice. This image shows recent gullies in a
crater wall.
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22
Where did the water go to?
  • Mars (and Venus) lost most of their water to
    space.
  • For Mars, frozen water is tied up in the
    subsurface and polar caps

23
  • Mars geologic history was once warmer and wetter
    than now.

24
Climate History
  • Atmosphere warmer in the past
  • Greenhouse effect due to CO2 and some CH4
  • Loss of CO2 to space
  • Polar caps insufficient to account for missing
    CO2
  • No good evidence for carbonates
  • Loss via impacts
  • Loss via the solar wind, which is not well
    deflected because of weaker magnetic field (core
    cools faster)
  • Loss of H2O
  • Loss via impacts
  • UV breaks up H2O and H2 escapes easily

25
Life on Mars???
  • Based upon our understanding of biology, Mars has
    all the necessary ingredients for life
  • Water, an energy source, and the basic elements
    and compounds required make life.
  • Mars likely had a very different climate in the
    past that was more hospitable to life.
  • Life on Earth is exceptionally tough (lives and
    survives under extreme conditions)!

26
Meteorite from Mars
  • ALH84001
  • possible evidence of fossil microbes from Mars?

27
Life on Mars? Martian Meteorite.
Fossil Life?
If this is life it is very small in size. Too
small? Some scientists are convinced it is
life. Most are still unsure.
28
Life on Mars?
It has been proven there is water ice on
Mars. Probably below the surface today but a
large ocean in the past. Water ? reasonable
possibility of life but is it extinct, dormant or
alive?
29
Life on Mars today?
Direct search by space probes 1976 Viking probes
- inconclusive 2003 Beagle II crashed on landing
30
Methane Water!
Data obtained by the Mars Express probe show that
water vapor and methane gas are concentrated in
the same regions of the Martian atmosphere.
31
Methane Water!
  • Data obtained by the Mars Express probe show that
    water vapor and methane gas are concentrated in
    the same regions of the Martian atmosphere.
  • Must be recently made!
  • Methane only lasts about 100 years (UV light
    destroys it)
  • Life (micro-organisms) or volcanoes?
  • If microbes are making methane in the Martian
    atmosphere as part of their living process, they
    would rely on water.

32
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