1. Is/Was there life on Mars?
Evidence of a Formerly Thicker Atmosphere
And Water

2. 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.

3. Where did the Atmosphere Go?
Two Hypotheses have been advanced to explain the disappearance of the Martian Atmosphere
Asteroid impacts blasted away the atmosphere.
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

4. 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

5. Water ice was found by Phoenix just beneath the surface in 2008

6. Curiosity and ancient water
Curiosity has found on Mars
Confirmation of Alluvial Fans
(River delta sediments)

7. Conglomerate
(sedimentary rock made of water smoothed pebbles and rocks)
in “streambeds”

8. 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.

9. 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 a meteorite from Mars that has been found on Earth has what might be fossilized bacteria…or not.
(geologic processes could have form the “fossils”)