How Long Does It Take to Get to Mars?
Updated: 1 day ago
The short answer: about seven months. With today's rockets, a spacecraft that leaves Earth in a launch window reaches Mars in roughly six to nine months. NASA's Perseverance rover took 203 days in 2020 and 2021. The fastest trip so far, the Mariner 7 flyby in 1969, took 131 days.
No human has made the journey yet, so every number below comes from robotic missions. A crew would travel on the same paths, with the same timetable.
Why it takes months, not days
The distance between Earth and Mars changes all the time, because both planets circle the Sun at different speeds. At their very closest it is about 54.6 million km, on average about 225 million km, and at their farthest, on opposite sides of the Sun, about 401 million km.
A spacecraft does not fly in a straight line. It is launched into its own orbit around the Sun and travels about half a loop until Mars arrives at the same point. This curved path, called a Hohmann transfer, is longer than the straight distance, but it needs the least fuel. Fuel is the real limit: every extra kilogram has to be lifted off Earth.
How long real missions took
Mariner 7 (1969, flyby): 131 days, the fastest so far
Mariner 4 (1964 to 1965, flyby): about 7.5 months
Curiosity (2011 to 2012, landing): about 8.5 months
Perseverance, Tianwen-1 and Hope (2020 to 2021): about 7 months each
A flyby can be quicker because it does not have to stop. An orbiter or a lander must brake hard on arrival, so it usually takes a slower, cheaper path.
The 26-month launch window
An efficient trip is only possible when Earth and Mars are in the right position, and that happens about every 26 months. Miss the window and you wait more than two years for the next one. That is why three missions, from the United States, China and the United Arab Emirates, all launched in July 2020. More on this in The Window Year: Why Ships Reach Mars Only Every 26 Months.
How long would a round trip take?
A crew could not simply turn around. After arriving, they would have to wait on Mars until the planets line up again for the way home, which takes about a year and a half. A full round trip would last about two and a half to three years.
Could we get there faster?
Stronger propulsion, such as the nuclear thermal rockets NASA is studying, could shorten the trip to a few months. These engines are still in development. A faster trip would matter mostly for people: fewer months of space radiation and weightlessness, and less food, water and oxygen to carry.
How long does a message take?
Even radio is not instant. A signal needs between 3 and 22 minutes to travel one way, depending on where the two planets are. A conversation between Earth and Mars is never live.
What this means in ICARUS
ICARUS is set on Mars in the 2090s, and this timetable shapes the whole story: ships arrive only in windows, and help from Earth is always months or years away. When a settlement is in trouble, the others on Mars are the only ones close enough to help. See Where on Mars Is ICARUS Set?, or step into the world and ask Luna.
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