If this seems hugely optimistic, it is. There's no doubt about that. But Musk was keen to demonstrate his drive to do this. He's going to be putting as much of his own money behind it as possible, which considering he's a mega-multi-billionaire is no small change.
“There's no other reason for me to accumulate assets than to make the biggest contribution I can to making life multiplanetary,” he said.
And that's in part the answer to a bigger question surrounding all this excitement. Why bother? Mars is a dead world. We can't live there without spacesuits or significant infrastructure. Why do we want to go there?
The answer is simple. Musk rightly says that humans will at one stage face a doomsday event, be it an asteroid impact or some other civilization-ending scenario. If we can't live on other worlds, we're pretty screwed.
With that in mind, Musk says he doesn't just want to stop at Mars. The ITS, he says, could conduct trips to other places including Jupiter's moon Europa and Saturn's moon Enceladus.
Is it achievable? Well, that's up for a very lengthy debate. Musk showed some snippets of development already taking place towards this goal, including the Raptor engines that will power the rocket and the giant fuel tank that will be used in the spaceship itself.
The spaceship can supposedly launch and land almost anywhere in the Solar System. Elon Musk/SpaceX
An early design of what the spaceship's fuel tank might look like. Elon Musk/SpaceX
But there's no doubt there are huge obstacles to overcome. How will the colony survive on Mars (this was not made clear)? Who will want to go? How will they deal with radiation (Musk suggested this wasn't a huge problem)?
These are questions that will be pored over the next few days, months, and years. For now, Musk said his goal is to inspire public and private companies to get involved with his mission. He wants a collaboration, he wants help. This is his call to arms.
“The first journeys will be very dangerous, the risk of fatalities will be high,” he said, adding that people must be prepared to die.
But judging by the roaring crowd, the huge media attention around this event, and Musk's own drive, it's not implausible to think it might happen. Musk highlighted how SpaceX had developed from almost nothing in 2002 to its position now as one of the leading launch operators in the world.
Can he really start a million-strong colony on Mars? Time will tell. Either today will go down in history as a JFK-esque moonshot speech, or we'll look back and wonder what might have been.
Here's hoping for the former.