Water on Mars and the Martian Atmosphere
- Liquid water flowed on the surface of Mars in the distant past (in the first billion years).
- Sinuous channels have characteristics of river beds, including
- Tributary systems suggest that water was distributed over a large area (evidence for rainfall?).
- Channels lead in and out of craters with smooth (sedimented)
bottoms and possible evidence for shorelines.
- Muddy craters demonstrate that portions of the crust
were/are saturated with frozen water.
- Collapsed terrain shows evidence that saturated frozen
crust was heated in places from below, producing
- River deltas and meanders suggest persistent
flow of water on early Mars.
- Recently, detailed images from orbit have revealed a region where significant
water may have emerged and frozen on the surface in recent history.
- Glaciers might be expected in this environment, and some evidence suppots past glacial activity.
- Two Mars Exploration Rovers landed at likely formerly wet sites in early 2004. One is still operating today (even though the primary mission was 90 days long).
- This evidence for flowing and standing water suggests that
the Martian atmosphere must have been much more dense in the past in order
to produce a warm enough climate (via the greenhouse effect) to permit liquid water to exist on the on the surface.
- Mars probably outgassed a substantial amount of CO2 like Venus and Earth (although probably a bit less given its smaller size and quicker cooling).
- Initially this CO2 produced a strong greenhouse
effect and made Mars a temperate place.
- Water disolved some of the CO2 and this CO2
was permanently disposed of via the formation of carbonate rocks
(similar to terrestrial limestone).
- The weak gravity of Mars is only marginally capable of
holding on to an atmosphere as well. Only a thin atmosphere remains today.
- On Earth, volcanic activity continually replenishes the
atmospheric CO2, providing our mild greenhouse
- Because it is a smaller world, volcanism on Mars ended long ago.
- All combined, one should not be too surprised to find
that there is little CO2 left on Mars today.
- The greenhouse effect is extremely weak and the
planet is frozen.
- Where is all the water today?
- The evidence listed above (muddy craters and
collapsed terrain) suggest that it is locked underground as permafrost.
- There is some interesting evidence that fluid water has flowed on the Martian surface recently. *
- If Mars started out like the Earth, did life get started on Mars as well???
- If it did, it may have evolved to keep pace with the
- A cursory search by the first landers revealed no
evidence for life.
- A meteorite found in Antartica may hold some tantalizing
clues concerning about whether life originated on Mars.
Revised April 17, 2012