1.   Over geological time it is likely that impacts have reduced the mass of the Martian atmosphere by a factor of one hundred.

2.   The problem lies in the virtual absence of water in the Martian atmosphere.

3.   The risky technique involves vehicles dipping into the Martian atmosphere to slow down, rather than firing braking rockets.

4.   The same materials, thrown into the Martian atmosphere by strong winds, give the Martian sky a pinkish color.

5.   Water fails to enter the Martian atmosphere because the surface temperature is very low.

6.   Among them is a device that would gather carbon dioxide from the Martian atmosphere and combine it with hydrogen to produce methane, a rocket fuel.

7.   As a result, the spacecraft plunged into the Martian atmosphere and was destroyed, instead of orbiting safely above the planet.

8.   After a parachute brakes its initial descent through the thin Martian atmosphere, a set of giant air bags are supposed to inflate to cushion the impact.

9.   After piercing the Martian atmosphere, the egg-shaped probe will descend by parachute.

10.   Experts say the orbiter probably burned up in the thin Martian atmosphere.