Take Back the Sky

by Jeff Cunningham

Those of you who have heard the occasional news bite about SpaceX’s efforts may have heard Elon Musk openly state that the Dragon’s true purpose for which it was designed all along has been to eventually travel to the planet Mars. You may be looking at the capsule spacecraft and find that the word that comes to your mind is “dinky.” Just how can a ship no larger than the Apollo capsule that took three men in very cramped quarters take that same crew all the way to the red planet without them coming down with the worst case of cabin fever in history? At six-foot-four-inches, I have a hard enough time in my Ford Focus, I can’t imagine practically living in it for the better part of a year with two or three other people.

It turns out that SpaceX’s creation is exactly the sort of thing that’s needed to reach and permanently colonize Mars (as opposed to plant the flag, take pictures of our footprints, then get back in, go home, and never come back, like we did with the moon), as today’s installment will show. Elon Musk has yet to reveal the specifics of what a mission to our neighboring world aboard a Dragon ship would look like, but the realities of engineering and rocket science are that there’s only so many ways that he can while optimizing the competing factors of speed, economy, and performance. What follows is the most likely mission profile of how Serenity could be followed by the first man on Mars.

Chances are, the whole thing, from start to finish, will strongly resemble or at least borrow from a mission architecture called Mars Direct. “Mission architecture” is the term that NASA uses to describe just how the different pieces of spaceship components will fit together and be used in every mission. In the Apollo program, a giant Saturn V rocket lifted a heavy package of the Apollo, the lander, and a smaller rocket into low Earth orbit (LEO) by staging several times just to get off of our planet. Once in space, the astronauts would fire the smaller rocket, called the Earth departure stage, that would change their orbit from going around the Earth to one that would go back and forth between the Earth and the moon, where the lander would detach and land on its surface. The lander would stage to return the astronauts to the Apollo, then everything else would be ditched and burn up in the atmosphere as the crew splashed down. By comparision, the shuttle’s mission architecture is far simpler, as was the aim in designing this truly advanced ship.

At launch, the solid rocket boosters ignite in concert with the shuttle’s main engines, which are fueled by a gigantic, external fuel tank (the orange cigar-looking thing). The other parts are cast away as their functions complete, leaving the orbiter itself in LEO, which then glides back to Earth to be re-used (the boosters were also reused after being fished out of the ocean and having all the salt scrubbed out).

Mars Direct is a very special mission architecture that was not concieved by NASA, but proposed by a very outspoken and passionate engineer. As an ordinary systems engineer within Martin-Marietta at the time, Robert Zubrin was convinced that NASA didn’t need gargantuan, Star Destroyer-sized rockets or exotic science fiction engines to reach the red planet and establish a presence there. On his own personal time, he crunched all the numbers and created an architecture of his own, using only existing tech (“off-the-shelf” in engineering parlance) for a budget equal to what NASA typically spent on a program at the time. The way it worked is this:

First, a heavy-lift rocket (the class of launcher that the space shuttle or Falcon Heavy would fall into) takes off for the surface of Mars. It will not carry any crew whatsoever, only an unmanned ship called an Earth Return Vehicle (ERV) for reasons that will soon become apparent. It lands on Mars on autopilot, containing enough food and supplies for a crew of astronauts to use it for their return trip home. In the meantime, however, a small propellant factory on board sucks in air from the Martian atmosphere and starts making the fuel it will need for that leg of the journey.

Earth Return Vehicle concept

It no doubt sounds strange to the average reader that we’d take care of the ride home before we leave, and the idea of making your own fuel sounds like a questionable proposition over the internet. Allow me to explain:

The atmosphere of Mars is roughly 98% carbon dioxide. If you take a small quantity of liquid hydrogen (same stuff the shuttle used) and combine the two, basic high school chemistry shows that you get methane and water. The latter has obvious uses, or can be split into oxygen to breath and more hydrogen to cycle back in and use; the former is going to be our fuel to return to Earth. It turns out that methane is actually a decent propellant for rockets, and, indeed, several manufacturers already make some that use it.

Two years later, if all checks out with the ERV and its tanks are full, then we send the people. Think about it: no matter what goes wrong on the way there, they know that they’re guaranteed a safe trip back to Earth before their mission even starts. Also this same year, while the planets are said to be “at conjunction,” that is, positioned on opposite sides of the sun thus making for a faster trip, a third rocket takes off carrying a second ERV — Two rockets every two years, one ERV and one crewed ship. Keep that in mind for later.

The intrepid, first crew of astronauts travels for six months in a combination habitat and martian lander that will have more living space than previous “cozier” craft. It may be decided to produce artificial gravity by keeping the last rocket stage attached to the ship after it empties at the end of a tether, then spinning the two end over end. They land, make history, and spend several months there instead of only a day or two so that they can actually do real exploration.

At the end of the mission, the crew boards the ERV and returns home, leaving their former habitat lander behind. This cycle repeats every two years: Send an ERV and a Crew module, Crew does a mission and comes home in the ERV, leaving behind their former living quarters each time. Guess what happens over the course of several of those missions?

Instant Martian base, all without spending one single dime in addition to the mission. When a suitable site is found by the astronauts, they just tow all the hab modules there with their rovers and hook them together. Also, you may have noticed that one great thing about a Mars Direct-like architecture is that two launches every two years equals an average of one launch per year. Even when the shuttle program was dying and their budget was terminally ill, they still managed one to two flights a year. Such a schedule is completely doable even under the worst circumstances. When you keep that in mind, it becomes easier to believe the numbers they calculated when they say that going to Mars this way would actually cost less than what we spent on the shuttle for each flight.

So, you may be wondering, as I and so many other people asked aloud when we heard this for the first time, “why aren’t they doing this?” Mars Direct represents yet another fundamental change from “the way things have always been done” when it comes to spaceflight. Fortunately for us, though, that’s where SpaceX comes in.

Elon Musk got in touch with Zubrin and banged out a way to use Dragon to make Mars Direct a reality. It turns out that it’ll be just as effective for landing on Mars as it already is in bringing astronauts back to Earth. What’s more, they’re already taking steps to prove their point: They’re pitching to NASA a mission they’re calling Red Dragon to land an unmanned Dragon on the surface of Mars in 2018 to perform all the science that they can cram in the thing: Searching for life, analyzing the planet’s former climate, prospecting for ice and other resources, you name it. The best part? Since SpaceX has already worked out all the ways to use their systems efficiently, they can get the cost down to less than $400 million — which sounds like a lot, until I tell you that this is less than half the cost of the recent and successful Curiosity rover.

Credit: SpaceX

Just think: Mars could become a new home, a new continent for people to live on. They’ll never need costly resupply missions like the space station because they’ll have everything they need there. They can make their own fuel, there’s way more ice than the theoretical stuff we have yet to find on the moon, the soil is great for growing crops in, and there’s a number of ways they can harvest or generate energy on their own. When future missions to deep space go wrong and have to abort, they’ll abort to Mars instead of Earth as the second safest place in the Solar system. It will be the stopover point on the way out to mining Phobos, Deimos (the twin moons of Mars) and harvesting the gases of Jupiter and Saturn that have the potential of saving Earth’s environment and ending the energy crisis forever. The day that mankind becomes a multi-planet society will be a profound change, indeed. That one giant leap will start with one small step that happens to be named Serenity.

Write Elon Musk today, and tell him that you think that’d be awesome.