Today, SpaceX CEO Elon Musk unveiled the Mars vehicle — the spaceship his company plans to build to transport the first colonists to Mars. The spaceship is meant to launch from Earth on top of the booster and then travel the rest of the way on its own to the Red Planet.

Though not finalized, the first spaceship will probably be named "Heart of Gold," a reference to the spacecraft in Douglas Adams’ Hitchhiker’s Guide to the Galaxy. It will have a diameter of 17 meters.

The plan is to send about 100 people per trip, though Musk wants to ultimately take 200 or more per flight to make the cost cheaper per person. The trip can take as little as 80 days or as many as 150 depending on the year and the technology. The hope is that the transport time will be only 30 days "in the more distant future."

The rocket booster will have a diameter of 12 meters and the stack height will be 122 meters. The spaceship should hold a cargo of up to 450 tons depending on how many refills can be done with the tanker.

As rumored, the Mars vehicle will be reusable and the spaceship will refuel in orbit. This is key, according to Musk, because refueling in orbit makes the trip much cheaper and hence more doable. Similarly, it’s inefficient to bring propellant for the return trip. Ideally, a team would build a propellant plant on Mars and send the ships back that way. (This is supposedly possible given the natural resources on the Red Planet.)

The trip will work like this: First, the spaceship will launch out of Pad 39A, which is under development right now at the Kennedy Space Center at Cape Canaveral, Florida. At liftoff, the booster will have 127,800 kilonewtons of thrust, or 28,730,000 pounds of thrust. Then, the spaceship and booster separate.

The spaceship heads to orbit, while the booster heads back to Earth, coming back within about 20 minutes. Back on Earth, the booster lands on a launch mount and a propellant tanker is loaded onto the booster. The entire unit — now filled with fuel — lifts off again. It joins with the spaceship, which is then refueled in orbit. The propellant tankers will go up anywhere from three to five times to fill the tanks of the spaceship.

The spaceship finally departs for Mars. To make the trip more attractive for its crew members, Musk promises that it’ll be "really fun" with zero-G games, movies, cabins, games, a restaurant.

Once it reaches Mars, the vehicle will land on the surface, using its rocket engines to lower itself gently down to the ground. The spaceship’s passengers will use the vehicle, as well as cargo and hardware that’s already been shipped over to Mars, to set up a long-term colony. At the rate of 20 to 50 total Mars trips, it will take anywhere from 40 to 100 years to achieve a fully self-sustaining civilization with one million people on Mars, says Musk.

Musk hasn’t yet addressed details about where people will live and eat, as well as some of the health-related concerns such as how the astronauts will deal with living in microgravity. For example, the ship in the promotional video doesn’t appear to be rotating to create artificial gravity, which raises questions about what it will be like inside and the amount of exercise that the astronauts would need to do to stay healthy.

The CEO also seemed unconcerned about solar radiation, which can cause serious cardiovascular disease, among other complications. "The radiation thing is often brought up, but it’s not too big of a deal," he says. There is a "slightly increased risk" of cancer, he says, and there will probably be some sort of shielding.

This will not be a one-way trip: it’s important to give people the option of returning, even if they decide not to go. And, in any case, "we need the spaceship back."

He provided few details on who first pioneers will be. "We’re trying to make it such that anyone can go" with "maybe a few days of training," he says. Musk does note that there will probably be no children since because the risk of fatality is high and astronauts need to be "prepared to die."

But hey, there’s always the zero-G games on the way there.

SpaceX trip to Mars simulation