Elon Musk finally did it. Fourteen years after founding SpaceX, and nine months after promising to reveal details about his plans to colonize Mars, the tech mogul made good on that promise Tuesday afternoon in Guadalajara, Mexico. Over the course of a 90-minute speech Musk, always a dreamer, shared his biggest and most ambitious dream with the world—how to colonize Mars and make humanity a multiplanetary species.

And what mighty ambitions they are. The Interplanetary Transport System he unveiled could carry 100 people at a time to Mars. Contrast that to the Apollo program, which carried just two astronauts at a time to the surface of the nearby Moon, and only for brief sojourns. Moreover, Musk’s rocket that would lift all of those people and propellant into orbit would be nearly four times as powerful as the mighty Saturn V booster. Musk envisions a self-sustaining Mars colony with at least a million residents by the end of the century.

Beyond this, what really stood out about Musk’s speech on Tuesday was the naked baring of his soul. Considering his mannerisms, passion, and the utter seriousness of his convictions, it felt at times like the man's entire life had led him to that particular stage. It took courage to make the speech, to propose the greatest space adventure of all time. His ideas, his architecture for getting it done—they’re all out there now for anyone to criticize, second guess, and doubt.

It is not everyday that one of the world’s notables, a true difference-maker, so completely eschews caution and reveals his deepest ambitions like Musk did with the Interplanetary Transport System. So let us look at those ambitions—the man laid bare, the space hardware he dreams of building—and then consider the feasibility of all this. Because what really matters is whether any of this fantastical stuff can actually happen.

The hardware

During his talk, Musk outlined an extremely large new rocket, with a primary structure made from carbon-fiber composites that are lighter and stronger than the aluminum and other metals used in traditional rockets. A staggering 42 Raptor engines, burning liquid oxygen and densified liquid methane, would power the Interplanetary Transport System (ITS) booster to orbit. “It’s a lot of engines,” Musk acknowledged. Presumably the software to integrate all of that power has come a long way since the Soviets tried their 30-engine N1 rocket in the late 60s and early 70s. All four N1 launches were failures.

The expendable variant of the ITS rocket would have an unprecedented lift capacity of 550 metric tons to low Earth orbit (LEO), which is roughly equivalent to 50 full-size yellow school buses. The most powerful rocket flying today, the Delta IV heavy, has a payload-to-LEO capacity of only about 28 metric tons; the most powerful rocket ever to successfully fly, the Saturn V, could haul 140 metric tons to LEO. Musk’s plan relies on a reusable variant of the the ITS rocket (300 tons to orbit), sending it up and landing it back at the launch pad. After accelerating to a staging velocity of 8,650km/h, the booster would use 7 percent of its propellant for a return trip.

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The ITS spaceship would stand 50 meters tall (the Apollo capsule was a mere 3 meters high) atop its rocket, with a maximum diameter of 17 meters. Instead of departing Earth orbit at 4.5km/s, its six Raptor engines optimized for the vacuum of space would accelerate it to 6 km/s, cutting the journey to Mars from six months to about three. After launching and being fueled on orbit, the ITS could deliver 450 tons to the surface of Mars. The largest payload NASA—or anyone—has ever safely landed on the Martian surface is the Curiosity rover, which weighs less than a single ton.

There are more details in the presentation SpaceX has posted on its Web site. Suffice it to say the company has proposed building breathtaking space machines orders of magnitude greater than NASA or anyone else has ever constructed. These are truly audacious space-faring vessels, designed to go where no one has gone before. They are almost unbelievable.

Really, Elon?

Understandably, one might dismiss Elon Musk as a crank, a once-promising visionary slowly degenerating into a Howard Hughes-like madness. A million people on cold, dead Mars? Humans haven’t even been to the Moon, which is right next door to Earth, in nearly half a century.

However, SpaceX has made some demonstrable technical progress. Engines represent the bedrock of any rocket, and SpaceX has already built a full-scale version of its Raptor engine, which it tested this month in Texas. The Raptor is approximately the same size as the company’s Merlin 1-D engine, but has three times the thrust due to its capability to withstand higher pressures.

Additionally, in one of the real “wow” moments of of Tuesday’s talk, Elon showed several photos of an ITS liquid oxygen tank, made of carbon fiber composites to withstand high pressures. This is real hardware, equivalent in scale to the tankage NASA is building for its SLS rocket , and offers some insight into the company’s plans.

It seems clear that SpaceX will build as much Mars hardware as it can afford, in hopes of showing the aerospace community and space agencies around the world that it is serious about this venture, and has the technical chops to pull it off. “As we show this is possible, that this dream is real, I think the support will snowball over time,” Musk said during his presentation.

Listing image by SpaceX