Leaving Earth | MARS: How to Get to Mars

We need to be able to get off of Earth better. So, first thing we need to work out is how to very efficiently get off of Earth. Then we can start working out how to efficiently get on to Mars. If you want to get off the planet Earth today, you’ve got one option: build and fly a rocket.

A rocket is basically a device that pumps a ton of energy down one way that moves a rocket the other way, and it's a way of fighting gravity. The main expense of spacecraft is building the booster itself, and right now we don't reuse boosters. SpaceX is trying desperately to get that going. The difference between a reusable system versus an expendable system is gonna be about a factor of a hundred.

Imagine if you took a flight from New York to London, and then at the end of the flight they threw away the plane. Imagine how much tickets would have to cost in order for the airline to make money. It'd be like hundreds of millions of dollars per seat because they’re throwing away a multi-billion dollar aircraft every time they fly.

What really matters is being able to send a large number of people—tens of thousands, if not hundreds of thousands—and millions of tons of cargo. I conservatively estimate you're gonna need a spaceship that weighs about a million kilograms. You need about 10 times the NASA ship in fuel, so now you're looking at 10 million kilograms put into low-earth orbit.

To get all of that up into low-earth orbit would cost phenomenal amounts of money. For our friends at the ISS, I think it was about a hundred and sixty-five billion dollars to put 380,000 kilograms up there. I mean, you do the math on that—it was a lot of money per kilogram. If you go to Congress right now and say like, "Well, it's gonna cost us two hundred billion dollars," they're gonna say like, "Well, I think we're gonna not do that."

If you go to them and say like, "Oh well, now thanks to better booster technology, it will now cost 10 billion dollars," well, they’re like, "We spend that much on the ISS every year. We're not gonna go anywhere or do anything until we drive down the price to low-earth orbit." That is the key to absolutely everything. Then we can start working out how to efficiently get on to Mars.