Transcript Is/Was there life on Mars?

Is/Was there life on Mars?
Evidence of a Formerly Thicker
Atmosphere
And Water
Channels Cut by
Flowing Water
Channels have been seen on Mars that are best explained as
being cut by flowing water.
This would imply that at one time the atmosphere was thick
enough and there was enough water for precipitation to
occur causing run-off in the form of rivers.
If the Martian atmosphere was thick enough for liquid
water its greenhouse effect would have made the planet
much warmer and thus suitable for life.
Where did the Atmosphere Go?
Two Hypotheses have been advanced to explain the
disappearance of the Martian Atmosphere
1. Asteroid impacts blasted away the atmosphere.
2. The low mass and thus gravity of Mars failed to
hold onto the atmosphere and gradually it was lost.
The cooling of the interior contributed by…
• Weakening the magnetic field exposing the
atmosphere to the solar wind
• Volcanic activity lessened so volcanoes did not
replenish the atmosphere
Where did the Water Go?
The Water seems to
be frozen in a layer
just below the
surface
Evidence for this is
the squished out
terrain near craters
where the heat
from the impact
melted the ice
beneath the surface
Water ice was recently
found by Phoenix just
beneath the surface
Curiosity and ancient water
Curiosity has found on Mars
• Confirmation of Alluvial Fans
(River delta sediments)
• Conglomerate
(sedimentary rock made of water smoothed
pebbles and rocks)
in “streambeds”
• Concretions:
( Rocks formed when water evaporates)
Like this vein of gypsum deposited in a crack in the rock
All this confirms the presence of liquid water in the past.
Life on Mars
No current evidence…but:
There is evidence that
once there may have
been..
• There once was a thick
enough atmosphere with
water
• Some claim that meteorite
from Mars that has been
found on Earth has what
might be fossilized
bacteria…or not.
(geologic processes could
have form the “fossils”)