OK, so who is ready to go live on Mars? I saw a few hands go up there in the Boulder Weekly readership. Now multiply that across the globe and you’ll have more than enough people to fill up one of Elon Musk’s proposed “Interplanetary Crew Transport” (ICT) vehicles, the primary component of his Interplanetary Transport System (ITS). Now, what the heck is that?
On Sept. 26 at the International Astronautical Congress in Guadalajara, Mexico, Elon Musk, the billionaire entrepreneur behind SpaceX and Tesla Motors, laid out his plans for sending, not just a few people, not just hundreds, but thousands and ultimately tens of thousands of people to the Red Planet. OK. So, one, just what is Elon Musk’s plan? And two, will it work?
Musk’s ITS plans involve building a fleet of the ICT spaceships. Each of which would be able to carry 450 tons of passengers and cargo to Mars.
Each of these craft would be the second stage of a new massive launch system. They would be launched into Earth orbit atop an enormous first stage booster rocket, larger than the Saturn 5 that launched the Apollo astronauts to the moon in the late 1960s and early ’70s. For purposes of comparison, the Saturn 5 weighed 3,039 tons at launch, the new ICT/booster stack would weigh 10,500 tons. The ICT spaceships would refuel in Earth orbit and then launch to Mars with a prodigious fuel burn that would act to shorten the trip to Mars from the standard six to eight months that current robotic missions take to just three months.
Keep in mind that traveling to Mars isn’t like driving from Chicago to Los Angeles. Well, it might be if both Chicago and LA were orbiting around St. Louis.
With Earth and Mars orbiting around the sun, traveling from one planet to another involves launching at the right time so that Mars (or the Earth if traveling in the reverse direction) is actually there once the spacecraft reaches its orbital distance from the sun.
But back to the Musk/SpaceX plan. The ICT would arrive at Mars and actually be capable of landing on the surface where it would refuel (using propellant derived from the Martian atmosphere and water in the near surface), and head back to Earth orbit to collect another set of passengers and cargo. Musk’s current plans don’t address major issues such as the radiation hazards of the interplanetary flight to Mars, or how the colonists would survive on the harsh surface of Mars.
To get a better idea of the viability of the Musk/SpaceX plan, I spoke with Dr. Robert Zubrin, president of Pioneer Astronautics of Lakewood, Colorado and the originator of one of the most widely celebrated Mars mission architectures, the Mars Direct concept (a mission profile that revolutionized thought about how Mars could be reached using largely existing technology and at a reasonable cost). Zubrin has some complimentary things to say about Elon Musk’s plans as well as some pointed criticisms.
Zubrin praises the approach that Elon Musk’s SpaceX Corporation has already taken to try to re-use the first stages of their now-operational Falcon 9 rockets. Zubrin says the successfully demonstrated approach of having the Falcon 9 first stages return to land on Earth tail-first under controlled rocket thrust will be adaptable to land SpaceX ICT rockets on Mars. Indeed, SpaceX plans to launch one of their Dragon crew capsules to Mars sans the crew, but with its descent rocket assembly in place in 2020 in order to test land a heavy payload (up to 7 and a half tons) on Mars. If successful, the landing of the “Red Dragon” spacecraft would mark the landing of the heaviest ever spacecraft on the Martian surface.
However, Zubrin says, “the real problem of the Musk approach is that it is vision-driven, not mission driven.” He sees the development of the ICT as an interplanetary spaceship as more of a goal than the actual mission of colonizing Mars. Moreover, he says that the use of a giant second stage and burning massive amounts of fuel to shorten the travel time is a detriment, since it reduces the amount of payload that can be taken to Mars by approximately three times. Also, Zubrin notes that by taking the ICT second stage to and from Mars, the Mars colonists would be losing potential living space. After all, “the people will need someplace to live once they get there,” he says, and the Musk plan is short on those details.
A better approach in Zubrin’s opinion is to “get out of the giant-interplanetary-spaceship-thought mode” and focus instead on sending “usable cargo instead of giant rockets” to Mars. Capitalize instead on the attractive parts of the plan — use the orbital refueling approach touted by Musk and utilize a soon-to-be-ready rocket, the SpaceX Falcon Heavy booster. The Falcon Heavy will be able to lift 54 tons to Earth orbit. By using on-orbit refueling, and a reusable orbital booster, much of that 54 tons could be sent directly to Mars where it would prove invaluable to any Mars colonists.
While the Interplanetary Transportation System plan of Elon Musk might seem incredible today, the thought of giant ocean liners crossing the Atlantic Ocean, let alone jumbo jet airliners, would have seemed incredible to the people of Europe at the time of Columbus. There is value in dreaming big dreams. To quote the poet Robert Browning, “Ah, but a man’s reach should exceed his grasp, Or what’s a heaven for?”
Bill Farrand is a Senior Research Scientist at Space Science Institute in Boulder. He is a Science Team Member on the Mars Exploration Rover mission and is a Boulder-area rock climber. He has a blog on space-related matters at drbill3000.tumblr.com.