How long does it take to travel to Mars?

Spacecraft don’t fly straight at Mars. They aim for where the planet will be months later, riding a long curved path around the sun. That’s why the trip takes about seven months, even though light makes the same crossing in minutes.

How far is Mars from Earth?

The distance changes constantly because both planets orbit the sun at different speeds. At their closest, Mars and Earth can be about 55 million km (34 million miles) apart. At their farthest, on opposite sides of the sun, the gap grows to around 400 million km (250 million miles).

Why launches only happen every 26 months

To save fuel, missions use a path called a Hohmann transfer orbit, an ellipse that touches Earth’s orbit at one end and Mars’s at the other. It only works when the planets are lined up just right, which happens roughly every 26 months. Miss that window and you wait two years for the next one. NASA, China and other agencies tend to launch their Mars missions in the same few weeks for exactly this reason.

What’s the fastest trip so far?

Small, light spacecraft that only flew past Mars made it quicker. NASA’s Mariner 6 and 7 flybys in 1969 reached the planet in about four to five months. Landers and rovers are heavier and have to slow down to enter orbit or land, so they usually take longer.

How long would a round trip to Mars take?

For astronauts, the trip out is only part of the story. After arriving, they would have to wait for Earth and Mars to line up again before heading home. Most mission plans put a full round trip at around two to three years, including a stay of over a year on the surface.

New engine ideas, such as nuclear thermal rockets, could cut the journey to a few months, but none have flown a crewed mission yet. For a sense of how hot the star at the center of all these orbits is, see how hot the sun is.