Reaching the Red Planet, Mars is a long and perilous journey – at least of with the current rocket technology
Mars at its most distant is a thousand times further that the Moon, which is itself a thousand times further that the International Space Station. This is a major reason why more than half of the Mars probes have failed. A manned mission would need some redundancy, including twin spacecraft. A suitable ‘launch window’ opens every two years and a chemical rocket trip might take seven to nine months. The main spacecraft would remain in the orbit while the landers dropped to the surface. Alternatively, ‘docking’ with the Martian moon Phobos might be simpler than immediately landing on the surface. Either way, after to four months, the return launch window would open, unless this is a long-term (or one-way) trip.
Cruising between worlds spells danger from cosmic radiation. Food and water (plus waste) packed around in the hull would double as radiation shielding. But the best way to cut exposure is to slash travel time. NASA hopes to do this with the VASIMIR plasma rocket – due for ISS testing in 2015. This could take a crew to Mars in 39 days, but to power the rocket for this length of time would require a yet-to-be developed fusion reactor.