Mars Sample Return (MSR) is dead and there are no plans to revive it soon. The basic Athena rover design originally intended for MSR was redesigned into Mars Exploration Rover (MER). The basic Entry Descent and Landing (EDL) system successfully used for Mars Pathfinder was reused as MER's EDL system. The group I'm with wasted considerable effort on the Earth Entry Vehicle (EEV) for MSR. The rules-of-engagement for designing EEV were completely ass-up. Rather than design for a working vehicle, we had to design for "failure". What does this mean? The design object of EEV was not to bring back a useful scientific sample put rather to create a vehicle that would not accidently release the sample under any conceivable circumstance. The EEV design was part of a long chain of ridiculous design requirements intended to insure that no forward or backwards biological contamination was possible. Millions of dollars was wasted on the exercise until almost everyone at the same time realized that the task was impossible. The whole thing was then bounced off the bottom of a dumpster and everyone walked away in disgust.

Exobiology is incompatible with legitimate Mars exploration.

Gary