How Long Does it Take to Get to Mars?


If you’re hoping to be one of those first human interplanetary explorers, you might want to know: how long does it take to get to Mars?

How long does it take to get to Mars?

The journey from Earth to Mars takes about 300 days.

Every two years Mars is at its closest point, only 55 million km from Earth, and it’s the ideal time to send a spacecraft. Travel time depends on the positions of the planets and how much fuel you’re willing to burn.

When you’re trying to get to Mars, just like in a car, spending more fuel means a shorter travel time. The first spacecraft to make this journey was NASA’s Mariner 4, launched on November 28, 1964 and arrived 228 days later.

This was a flyby mission, where the spacecraft took only 21 grainy photographs of the Martian surface. Since that first flyby, there have been a total of 21 successful missions sent to the red planet.

This doesn’t include a few partial successes and many many failures.

So, why does it take so long?

If Mars is only 55 million km away and if a spacecraft can travel at 20,000 km/hour, you would expect the journey to take only 115 days, but it actually takes much longer. You can’t just point your spacecraft at Mars and start firing your rockets. Because by the time you got there, Mars would have moved.Instead, spacecraft need to be pointed at where Mars is going to be. Then you would follow a trajectory which gets you to your destination using the least amount of fuel possible.

Hohmann Transfer - Image Credit: Gary Kezele

Hohmann Transfer – Image Credit: Gary Kezele

This is trajectory is called a Hohmann Orbit, and was first proposed by Walter Hohmann in 1925.Here’s how it works. You boost the orbit of your spacecraft so that it’s following a larger orbit around the Sun than the Earth. Eventually that orbit will intersect the orbit of Mars – the exact moment Mars is there too. If you’ve got less fuel, you just take longer to raise your orbit, which the increases your travel time.

Are you impatient to get to Mars and want to decrease your flight time?

Here are some drawing board proposals to shorten the travel times:

We could use Nuclear rockets.

These work by heating up a propellent to incredible temperatures and then blasting it out a rocket nozzle at high velocity to create thrust. This gives you higher thrust velocity with less fuel and could decrease travel time down to 7 months.

Or a there’s a Variable Specific Impulse Magnetoplasma Rocket (or VASIMR) which uses radio waves to ionize a propellant which would then be accelerated out the back of the spacecraft using a powerful magnetic field. A VASIMR engine could decrease Mars travel time down to 5 months.

An antimatter rocket is a proposed class of rockets that use antimatter as their power source.

An antimatter rocket is a proposed class of rockets that use antimatter as their power source.

The most exotic solution is antimatter. When atoms of matter meet antimatter, they transform into pure energy. Just milligrams of antimatter would provide enough fuel to propel a human mission to Mars in only 45 days. But there are so many unknowns for creating and storing that much antimatter, that it’ll be decades before it’s ready for a real mission.

There are plenty more missions planned, and engineers will be testing out these new technologies, and coming up with even more ideas. So maybe one day, getting to Mars will be as quick and easy as going on a cruise, or taking a road trip.