THE SCIENCE OF MARS:

Prelude to the next Invasion

 

18 years passed between the landings of the Viking spacecraft and the arrival of the next probe to Mars. In that time, the analysis of the data obtained so far was pushed as far as it could go, and the strategy for the next generation of robotic invaders was formulated.

 

Before we can understand the rationale for this next round of investigations, we need to summarize some of what was then known.

 

Geologic Epochs

 

 

Surface Texture – Radar Scattering

 

Surface Texture – Thermal Inertia

 

Densities of relevant materials varies by a factor of ~4

          Specific heat varies by 10%-20%

Thermal conductivity varies by up to 3 orders of magnitude (103 times)!!

 

K low for fine, unbonded materials

K intermediate for medium sands, fine sand + pebbles, crusted fines

K large for solid rock

 

Only gives average particle sizes/cohesion

 

Surface Rocks

 

 

 

 

 

 

Iron oxides with strong Fe+3 absorption bands in the near-IR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Note: strongest feature due to sulfur, probably in the form of sulfates. The carbonate feature may not be real. Carbonates do not show up in more recent observations.

 

 

Dust Processes

 

 

Wind Streaks

Polar Caps

 

South Polar Cap. The ÒextensionÓ to the upper right are the ÒMountains of MitchelÓ, a region where the frost remains for some time as the cap retreats during southern summer. There are actually no real mountains, and the name is not officially recognized by the International Astronomical Union.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Evidence that the NPC contains water ice. Most of the water in the form of polar caps are probably here (where the elevation is low for Mars, geologically-speaking. However, recent results indicate that the SPC also contains much water ice. So water is on mars, frozen in the polar caps, and in subsurface ice (permafrost) mostly at latitudes 30¡ or more from the equator.

 

 

Polar Layered Terrain

 

 

Both polar regions have associated layered (or laminated) terrain. This is a Viking orbiter picture of a portion of the layered terrain at 84¡M. The cliff drops off about 500m from the cap ice (white), and contains layers approximately 50m thick. The layering may contain the history of climatic changes on Mars over the past million years.

 

The layered terrain near the SPC was chosen as the landing site for the Mars Polar Lander.

 

 

 

 

 

 

 

For the best compendium of summaries of Mars science as of the early 1990Õs: