He did not. This is a common myth with Mars missions that was started by a company called Mars One. This company was the first to announce a mission to Mars, but they never had a single piece of flight hardware, and only had fancy 3d animations. They did however have a lot of 'applications' for becoming an astronaut while the applicants had to pay money to apply. While I'm sure the founders of Mars One had good intentions, it resulted in eventually being a scam.

This unfortunately resulted in people thinking Mars is a 'one way' mission. Elon Musk has repeated that to make live on Mars sustainable, you need roundtrips. You can't keep making new rockets, eventually you need them back. Otherwise it would become too expensive.

Info here: https://en.wikipedia.org/wiki/Mars_One

Nope. The whole point of developing the Raptor Engine was (A) to be able to reuse it and (B) to refuel on mars (using the Sabatier reaction with atmospheric CO2) for a return mission.

From Dr. Zubrin's Reddit AMA:

> for Mars Ascent and Earth return, SpaceX should develop a mini Starship, sized to be an upper stage of an F9. This would create a fully reusable medium lift booster, and reduce Mars propellant making requirements by a factor of 5. A Starsip could lift one of these to LEO fully fueled, after which it could fly to Mars, and return. any full sized Starships that land on Mars should stay on Mars. SpaceX will make plenty of Starships, it won't need any back that go to Mars. A Starship on Mars is much more valuable than one on Earth.

https://old.reddit.com/r/spacex/comments/hgy64k/ask_me_anyth...

Which seems to make sense, but I don't think SpaceX wants to develop another vehicle. That's extremely expensive. The goal of Starship is to do both, and it can do both.

It also gets debunked by replies. This will never happen.

I believe those people would have accumulated enormous radiation dosages over the duration of the flight, they might not have a long life left and a return voyage would shorten that even more. Might as well stay put for the remaining time on Earth, err, Mars, stay in deep lava tubes and help build that colony.

> those people would have accumulated enormous radiation dosages over the duration of the flight

What is this based on? One of the chief contributors to the mass of a Mars voyage is shielding.

You can't really shield against galactic cosmic rays (too high energy, would require far too much mass), which make up approximately 95% of the dose.

https://science.sciencemag.org/content/340/6136/1080.abstrac...

*Edit - but the comment higher up isn't right either, that most Mars-bound astronauts will have decreased lives. The paper linked above estimates 3% of astronauts to die from cancer caused by the trip (assuming no exposure on the surface of Mars, meaning they're in the ground).

And if the worst thing that happens to early Mars astronauts is "a 3% increase in the chance of dying from cancer someday", they will ecstatic. The list of more pressing risks is long.

NASA studies indicate a two year round trip to Mars (with roughly a year of surface time) would increase cancer rates by only 4%.