The Constellation program, to establish a permanent manned base on the Moon, is the testing ground for the first human exploration to Mars and beyond. For astronauts to explore Mars, they must be able to withstand the physiological effects, physical hazards and psychological strain of extended periods of time in deep space. The journey alone will take six months and the effects of chronic exposure to zero gravity and prolonged low dose radiation on the body have to be minimised. Yet the greatest threat to a Mars mission might be the mental welfare of the crew and how they interact with one another.

People skills and cooperation as well as extreme physical fitness will be a fundamental element to a successful long haul mission. Problems of extended space missions include the loneliness of relentless work necessary during the journey. Astronauts who stayed on the space station Mir for periods of four and five months expressed feelings of isolation and depression. The effect of six months stay on International Space Station crew has changed how NASA selects ASCANS and trains astronauts for extended missions.

Future manned deep space exploration requires that humans can not only survive a long duration missions, but also adapt to the new environment and successfully readapt upon return to Earth.