A quick note on Martian aircraft...
Unless Mars is to be terraformed (SimEarth!), aircraft flying in the Martian atmosphere will have to have huge wingspans to get enough lift to carry a significant amount of weight. The faster your craft, the less of a requirement this becomes.
Dirigibles might be a good solution. If I'm not mistaken, CO2 is relatively denser than the air mixture in earth's atmosphere. IF that's correct, helium or hydrogen will be 'relatively' lighter in the martian atmosphere and therfore reasonably effective? Hydrogen-filled blimps could lend themselves to some outstanding disasters with all those other hydrogen generating plants scatterd throughout the landscape. whhhooOOOOOOOOSSSHHHH!