Elon Musk really wants you to go to Mars. So much so that hes just released a free paper in the journal New Space outlining how hes going to get you there, and what youll do on the way.
In order to make it appealing  it has got to be really fun and exciting it cannot feel cramped or boring, Musk writes.
Therefore, the crew compartment or the occupant compartment is set up so that you can do zero-gravity games you can float around. There will be movies, lecture halls, cabins, and a restaurant. It will be really fun to go. You are going to have a great time!
We first learned about Musks plans to send people to Mars, and ultimately colonize it, in September 2016. In this commentary, hes now put pen to paper on some of those ideas. As before, yes, a lot of it is a bit far-fetched but theres some serious science there too.
History is going to bifurcate along two directions, Musk begins in typical Musky fashion. One path is we stay on Earth forever, and then there will be some eventual extinction event.
The alternative is to become a space-bearing civilization and a multi-planetary species, which I hope you would agree is the right way to go.
How he wants to achieve this is with his Interplanetary Transport System (ITS). Comprising a reusable rocket the largest ever built and a shuttle-esque vehicle, Musk envisions this transporting people on regular trips to Mars. Within a century, he wants 1 million people to be living on Mars.
Whether that will happen is up for debate. But the journey towards that goal does seem kind of possible. SpaceX hopes to start sending unmanned missions to Mars as early as 2020, with manned missions to follow down the line.
The main barrier to getting people to Mars, Musk says, is cost. You cannot create a self-sustaining civilization if the ticket price is $10 billion per person, he says.
If we can get the cost of moving to Mars to be roughly equivalent to a median house price in the United States, which is around $200,000, then I think the probability of establishing a self-sustaining civilization is very high. I think it would almost certainly occur.
Making this possible is several-fold. It includes making launch vehicles reusable, like SpaceX have been doing with their Falcon 9 rocket. It also involves finding ways to make propellant on Mars, perhaps using its carbon dioxide to produce usable methane and oxygen.
The transportation ship itself is probably the most controversial part of Musks plan. He wants the vehicle to be reusable 1,000 times, with up to 100 people on board. And he doesnt want just one. Oh no.
You would ultimately have upwards of 1,000 or more spaceships waiting in orbit, he said. Hence, the Mars Colonial fleet would depart en masse.
The ships will need to be big, he says, to get enough people and cargo to Mars: [T]o build everything from iron foundries to pizza joints to you name it we need to carry a lot of cargo.
And getting a million people on Mars eventually would be no mean feat. Assuming you go every two years, when Mars and Earth align for easy transit between them (Musk envisions travel time as short as 80 days with his system), youd need 10,000 trips with 100 people on each ship. Thats quite a lot although he notes that could be upped to 200.
[I]t would take 40100 years to achieve a fully self-sustaining civilization on Mars, he says.
The giant rocket itself would be made of an advanced carbon fiber, presumably to keep weight down while still remaining kind of strong. It would ultimately be capable of lifting about 500 metric tonnes (550 US tons) in expendable mode (where the rocket is not recovered), and 270tonnes (300 tons) in reusable mode. The Saturn V for comparison, the biggest rocket launched to date, could lift 140tonnes (155 tons).
There are plenty more interesting tidbits in the paper, so its worth a read if you felt Musks talk was a bit light on some of the science involved in this endeavor.
He admits that they were intentionally fuzzy on when this might all happen. In four years, he plans to complete the first development spaceship. In 10 years, if things go super-well, the first Mars colonization missions could begin.
There is a good chance we will not succeed, but we are going to do our best and try to make as much progress as possible, says Musk. And it might not just be Mars he has grander plans for sending people to Jupiters moons Europa and Enceladus, or Saturns moon Titan, or even Pluto.
[Y]ou could travel out to the Kuiper Belt, to the Oort cloud, he writes. I would not recommend this for interstellar journeys, but this basic system provided we have filling stations along the way means full access to the entire greater solar system.
Maybe let’s take a few baby steps first though, eh?