Ever wondered how long it would take to get to Mars?

With Elon Musk's successful launch of the world's most powerful rocket – SpaceX's Falcon Heavy – on February 6, humans journeying to Mars looks increasingly likely.

The problem is that there's an immense distance between Earth and Mars, which means any trip to the red planet will take a very long time.

It's also made more complicated by the fact that the distance is constantly changing as the two planets rotate around the sun.

The closest that the Earth and Mars would ever be is a distance of 33.9million miles – that's 9,800 times the distance between London and New York.

That's really rare though: the more useful distance is the average, which is 140million miles.

We've already launched a whole bunch of spacecraft to (or near) Mars, so we have a rough idea of how long it takes with current technology.

Historically, the trip has taken anywhere from 128 days to 333 days, which is a huge length of time for humans to be onboard a cramped spacecraft.

SpaceX's recently launched Falcon Heavy payload – which includes a Tesla car – is expected to pass Mars by around October, although there's no official public estimate.

Tech mogul Elon Musk – who heads up SpaceX – says his Interplanetary Transport System (ITS) could manage the journey in just 80 days.

Musk's firm is spending tens of millions of dollars on the project each year, and expects it to cost more than $10billion (£7.2billion) overall.

It's expected that most of Musk's engineers will be working on ITS by the end of 2018, with the end goal of colonizing Mars.

SpaceX currently expects to send its first cargo mission to Mars in 2022, with a human mission mooted for 2024.

Excitingly, Musk believes that his ITS ship will eventually be able to manage the Earth to Mars journey in just 30 days.

NASA reckons it could beat Musk's time though, if it can scale up a propulsion technology that uses a stream of photons – rather than fuel – to propel a spacecraft.

The system would involve kitting out a spaceship with reflectors that could be struck by photons, propelling it forward.

Scientists have achieved nippy speeds on a tiny level in laboroties, but we're still years away from using it to propel a large, heavy object like a spacecraft.

But if NASA can crack the puzzle, the travel time of a small 100kg craft could be reduced to just three days.

This story first appeared in The Sun.