How long does it take an astronaut to get to Mars?

The journey happens in free fall: you leave Earth on a trajectory that intersects Mars's orbit, then let celestial mechanics do the work. The Perseverance rover launched on July 30, 2020, and landed in Jezero crater on February 18, 2021, after a seven-month cruise. A crewed mission would follow the same principle: the duration of the trip depends on the launch window and the amount of propellant one is willing to spend, not on engine power during the crossing.

Earth and Mars are not always well positioned: departures are only possible for a few weeks, and the opportunity returns only about every two years. That's why probes leave in waves, with several agencies taking advantage of the same window. For a crew, the constraint is far heavier: once there, they would have to wait for the configuration favorable to the return to arise. Depending on the chosen profile, this means either a short stay on Mars at the cost of a faster, more expensive trip, or a long stay on the ground with economical trips.

The schedule isn't just a matter of planning: outside Earth's magnetic field, the crew absorbs continuous cosmic radiation, with the possibility of a solar flare along the way. Added to this are bone and muscle loss, the effects of weightlessness on vision, isolation, and a communications delay that rules out any real-time dialogue with the ground. It is this accumulation, more than the distance, that makes the trip duration the critical parameter: every week saved reduces the dose received and the amount of supplies to carry.