By Robert Zubrin, Wall Street Journal, 05.14.11
SpaceX, a private firm that develops rockets and spacecraft, recently announced it will field a heavy lift rocket within two years that can deliver more than twice the payload of any booster now flying. This poses a thrilling question: Can we reach Mars in this decade?
It may seem incredible—since conventional presentations of human Mars exploration missions are filled with depictions of gigantic, futuristic, nuclear-powered interplanetary spaceships whose operations are supported by a virtual parallel universe of orbital infrastructure. There’s nothing like that on the horizon. But I believe we could reach Mars with the tools we have today, or will have in short order. Here's how it could be done:
The SpaceX’s Falcon Heavy rocket will have a launch capacity of 53 metric tons to low Earth orbit. This means that if a conventional hydrogen-oxygen chemical rocket upper stage were added, it would have the capability of sending 17.5 tons on a trajectory to Mars, placing 14 tons in Mars orbit, or landing 11 tons on the Martian surface.
The company has also developed and is in the process of demonstrating a crew capsule, known as the Dragon, which has a mass of about eight tons. While its current intended mission is to ferry up to seven astronauts to the International Space Station, the Dragon’s heat shield system is capable of withstanding re-entry from interplanetary trajectories, not just from Earth orbit. It’s rather small for an interplanetary spaceship, but it is designed for multiyear life, and it should be spacious enough for a crew of two astronauts who have the right stuff.
Thus a Mars mission could be accomplished utilizing three Falcon Heavy launches. One would deliver to Mars orbit an unmanned Dragon capsule with a kerosene/oxygen chemical rocket stage of sufficient power to drive it back to Earth. This is the Earth Return Vehicle.
A second launch will deliver to the Martian surface an 11-ton payload consisting of a two-ton Mars Ascent Vehicle employing a single methane/oxygen rocket propulsion stage, a small automated chemical reactor system, three tons of surface exploration gear, and a 10-kilowatt power supply, which could be either nuclear or solar.
The Mars Ascent Vehicle would carry 2.6 tons of methane in its propellant tanks, but not the nine tons of liquid oxygen required to burn it. Instead, the oxygen could be made over a 500-day period by using the chemical reactor to break down the carbon dioxide that composes 95% of the Martian atmosphere.
Using technology to generate oxygen rather than transporting it saves a great deal of mass. It also provides copious power and unlimited oxygen to the crew once they arrive.
Once these elements are in place, the third launch would occur, which would send a Dragon capsule with a crew of two astronauts on a direct trajectory to Mars. The capsule would carry 2500 kilograms of consumables—sufficient, if water and oxygen recycling systems are employed, to support the two-person crew for up to three years. Given the available payload capacity, a light ground vehicle and several hundred kilograms of science instruments could be taken along as well.
The crew would reach Mars in six months and land their Dragon capsule near the Mars Ascent Vehicle. They would spend the next year and a half exploring.
Using their ground vehicle for mobility and the Dragon as their home and laboratory, they could search the Martian surface for fossil evidence of past life that may have existed in the past when the Red Planet featured standing bodies of liquid water. They also could set up drilling rigs to bring up samples of subsurface water, within which native microbial life may yet persist to this day. If they find either, it will prove that life is not unique to the Earth, answering a question that thinking men and women have wondered upon for millennia.
At the end of their 18-month surface stay, the crew would transfer to the Mars Ascent Vehicle, take off, and rendezvous with the Earth Return Vehicle in orbit. This craft would then take them on a six-month flight back to Earth, whereupon it would enter the atmosphere and splash down to an ocean landing.
There is nothing in this plan that is beyond our current level of technology. Nor would the costs be excessive. Falcon Heavy launches are priced at about $100 million each, and Dragons are even cheaper. Adopting such an approach, we could send expeditions to Mars at half the mission cost currently required to launch a Space Shuttle flight.
What is required,
however, is a different attitude towards risk than currently pervades the space
policy bureaucracy. There is no question that the plan proposed here involves
considerable risk. So does any plan that actually involves sending humans to
Mars, rather than talking about it indefinitely. True, there are a variety of
precursor missions, technology developments and testing programs that might be recommended as ways of reducing risk. There are an infinite number of such potential missions and programs. If we try to do even a significant fraction of them before committing to the mission we will never get to Mars.
But is it responsible to forgo any expenditure that might reduce somewhat the risk to the crew? I believe so. The purpose of the space program is to explore space, and its expenditures come at the cost of other national priorities. If we want to reduce risk to human life, there are vastly more effective ways of doing so than by spending $10 billion per year for the next two or three decades on a human spaceflight program mired for study purposes in low Earth orbit. We could spend the money on childhood vaccinations, fire escape inspections, highway repairs, better body armor for the troops—take your pick. For NASA managers to demand that the mission be delayed for decades while several hundred billion dollars is spent to marginally reduce the risk to a handful of volunteers, when the same funds spent elsewhere could save the lives of tens of thousands, is narcissistic in the extreme.
The Falcon Heavy is
scheduled for its first flight in 2013. All of the other hardware elements
described in this plan could be made ready for flight within the next few years
as well. NASA’s astronauts have gone nowhere new since 1972, but these four
decades of wasteful stagnation need not continue endlessly. If President Obama
were to act decisively, and bravely embrace this plan, we could have our first
team of human explorers on the Red Planet by 2016.
The American people want and deserve a space program that is really going somewhere. It’s time they got one. Fortune Favors the Bold. Mr. President, seize the day.
Dr. Zubrin is president of Pioneer Astronautics and of the Mars Society (www.marssociety.org). An updated edition of his book, “The Case for Mars: The Plan to Settle the Red Planet and Why We Must,” will be published by The Free Press this June.