Elon Musk is trying to make humanity a multi-planet species, starting with the colonization of Mars (that’s the raison d’être of his company, SpaceX).

Why Mars? The tech visionary laid out his argument in a article in the journal New Space this month.

In short:

Our options for becoming a multi-planetary species within our solar system are limited. We have, in terms of nearby options, Venus, but Venus is a high-pressure — super-high-pressure — hot acid bath, so that would be a tricky one. Venus is not at all like the goddess. So, it would be really difficult to make things work on Venus.

Then, there is Mercury, but that is way too close to the sun. We could potentially go onto one of the moons of Jupiter or Saturn, but those are quite far out, much further from the sun, and much harder to get to.

It really only leaves us with one option if we want to become a multi-planetary civilization, and that is Mars. We could conceivably go to our moon, and I actually have nothing against going to the moon, but I think it is challenging to become multi-planetary on the moon because it is much smaller than a planet. It does not have any atmosphere. It is not as resource-rich as Mars. It has got a 28-day day, whereas the Mars day is 24.5 hours. In general, Mars is far better-suited ultimately to scale up to be a self-sustaining civilization.

Musk’s Mars vision differs, of course, from the recently resurgent interest in Earth’s moon pushed by the Trump administration.

Musk also brought up terraforming again, suggesting that human intervention could make the red planet a lot greener.

In fact, we now believe that early Mars was a lot like Earth. In effect, if we could warm Mars up, we would once again have a thick atmosphere and liquid oceans. Mars is about half as far again from the sun as Earth is, so it still has decent sunlight. It is a little cold, but we can warm it up. It has a very helpful atmosphere, which, being primarily CO2 with some nitrogen and argon and a few other trace elements, means that we can grow plants on Mars just by compressing the atmosphere.

And if that’s not enough, we’ll get super powers on Mars:

It would be quite fun to be on Mars because you would have gravity that is about 37% of that of Earth, so you would be able to lift heavy things and bound around.

Musk also laid out a plan for getting the cost of a ticket to Mars down to around $200,000, with SpaceX’s first Mars flights happening around 2023. At that point it might not be long before humanity finally has a backup planet.

We just need to change the populations because currently we have seven billion people on Earth and none on Mars.

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Photos via Spacex