Martian Expedition Constraints

• The crew must be able to make an emergency return without use of Martian resources
• The only guaranteed resource is thin, cold carbon dioxide
• The crew should be able to survive at Mars until a duplicate ship can arrive
• The expedition should fail gracefully, that is that individual failures, breakages, etc. should reduce what may be achieved, without jeopardising the entire expedition
• Single points of failure are unacceptable

• Success at local resource use should result in proportionally reduced return time
• All crewmembers must have the oportunity to land on the surface. It is psycologically unacceptable to fly all that way and not do so.