Risky Business - manned flight to Mars

The Russian module launch marked a critical milestone toward a permanent human presence on the International Space Station, but many people would rather see expedited plans for more ambitious and distant missions piloted by people. Recent discoveries indicating subterranean water on Mars and oceans below Europa's ice sheets have renewed calls from the Planetary Society and other advocacy groups to reinstate a goal lost after the last Apollo moon landing in 1972: human exploration beyond Earth orbit. But NASA seems devoted to robotic probes, which circumvent the difficulties of supporting human life far from terra firma. Space, flight surgeons emphasize, is not exactly a safe place. Some of this risk assessment comes from learning by doing: We have definitively measured the irreversible bone loss suffered by long-term orbiting astronauts, for example. Other insight comes from reviewing our humbling inability to predict mechanical failures like the abrupt decompression that killed three Soyuz 11 cosmonauts in 1971.