How the extraction of lunar hydrogen or ice could fuel humanity's expansion into space
This is part of IEEE Spectrum's Special Report: Why Mars? Why Now?
Planetary geologists speculate that the moon’s polar craters may hold billions of tons of hydrogen, perhaps even in the form of water ice. Intriguing evidence returned by the Lunar Prospector and the Clementine probes in the 1990s seemed to support this idea. The latest raft of lunar missions, including Chandrayaan-1 and the Lunar Reconnaissance Orbiter, may confirm it. In situ prospecting could then determine the quantity, quality, and accessibility of the hydrogen.
Discovering rich concentrations of hydrogen on the moon would open up a universe of possibilities—literally. Rocket fuels and consumables that now cost an average of US $10 000 per kilogram to loft could instead be produced on the moon much more cheaply. For the first time, access to space would be truly economical. At last, people would be able to begin new ventures, including space tourism, space-debris cleanup, satellite refueling, and interplanetary voyages.
Lunar prospecting will cost a lot of money—perhaps $20 billion over a decade. Rovers would have to descend into the polar craters to sample the deposits and test for ice, and then move on to other spots to form an overall map, much as wildcatters do every day in oil fields.
At the moment, no country seems eager to foot the bill. But where governments fail to act on a vitally important opportunity, the private sector can and should step in.
Two years ago, I and a group of like-minded businessmen, expeditionary explorers, and space-systems managers and engineers formed the Shackleton Energy Co. in Del Valle, Texas, to conduct lunar prospecting. Should we find significant reserves of ice, we would then establish a network of refueling service stations in low Earth orbit and on the moon to process and provide fuel and consumables. Like modern highway service stations, these celestial stations would be able to refuel space vehicles of all kinds and would be positioned at key transportation nodes; an obvious spot would be near the International Space Station.
Such stations would radically change the way nearly every space system is designed. No longer would you have to carry your fuel and water into orbit with you. Entirely new classes of space vehicles would become possible, ones that operate only at and beyond low Earth orbit, such as vehicles for orbital transfer and satellite repair. Today launch systems must be designed to withstand the punishing effects of high-speed atmospheric drag, pressure, vibration, and heating that occur on the way to space. Protecting the rocket and its payload adds enormously to launch costs. But a vehicle that is designed from the start to operate only in space—say, between low Earth orbit and the moon—is not bound by the same design rules.
We would also be able to clear up the ever-growing space debris problem. There’d be plenty of fuel for maneuvering satellites and other spacecraft to avoid debris, and you could also deploy cleanup vehicles to remove obsolete materials from orbit. Within a decade or two, we would soon see the dawn of a new age of space exploration, space tourism, and space business ventures.
So where exactly is the raw material, and how will we retrieve it? The most likely place to look is within the regolith—the loose surface material—at the bottom of lunar craters, such as Shackleton Crater at the moon’s south pole. The cold interior of this crater may act as a trap that captures volatiles like water and hydrogen, which scientists believe may have been shed by comets and asteroids that collided with the moon. In the 1990s, the Lunar Prospector spacecraft sensed unexpectedly high amounts of hydrogen in the polar regions, which may indicate the presence of water ice. NASA has considered Shackleton Crater as the site for the first lunar outpost under its Constellation program, which envisions returning astronauts to the moon by 2020.
Assuming the ice exists and can be extracted, our plan calls for establishing a fuel-processing operation on the lunar surface. The first step would be to melt the ice and purify the water. Next, we’d electrolyze the water into gaseous hydrogen and oxygen, and then condense the gases into liquid hydrogen and liquid oxygen and also process them into hydrogen peroxide, all of which could be used as rocket fuels. Should other volatiles like ammonia or methane be discovered, they, too, would be processed into fuel, fertilizer, and other useful products.
Getting the fuels and other consumables from the moon into low Earth orbit will be relatively cheap. Because of the peculiarities of celestial mechanics, such a haul requires just 1/14th to 1/20th of the fuel it takes to bring material up from Earth.
Prospecting within the crater won’t be easy, of course. It’s extremely cold (a steady −173 °C) and perpetually dark—like an Antarctic winter but worse, because it’s constant. Also, the moon’s low gravitational field makes excavating that much trickier than it is back on Earth. Our plan therefore calls for developing a new generation of highly reliable, human-tended robotic machinery that would be built to withstand even that harsh environment. We think it can be done. We won’t know unless we try.
Three elements are essential for the commercial success of our operation.
First, to save about $1 billion during the initial staging of the lunar mining base, the first human team will take only enough fuel to land and establish the base—not enough for a return trip to Earth. This may sound radical, but the human crew who will undertake this mission will do so knowing that their success and survival depend on in situ fuel generation for the return. Should they fail, theirs will be a one-way trip; the risk is theirs to take. For government-sponsored space agencies, such a concept is unthinkable; they cannot tolerate the political risk of failure. Yet it is the only viable business choice. Centuries of explorers made the same hard choice in pushing the limits on land, sea, and air. It’s time to carry it forward into space. This is not reckless bravado but calculated risk management to satisfy mission needs and affordability.
Second, we need a relatively inexpensive means of returning to low Earth orbit. To do that involves the dissipation of nearly 3 kilometers per second of excess velocity. Decelerating with rocket propellant alone would be prohibitively expensive—we’d be ”eating the seed corn.” So we plan to do it with actively controlled aerobraking. The water-laden spacecraft will repeatedly dip into and skip out of the upper atmosphere, losing some velocity with each dip, until it ultimately ends up in the orbit of the fueling station. This same maneuver was previously used only for much smaller planetary robotic missions, such as Magellan and the Mars Global Surveyor, but the physics and engineering are well understood. We intend to take the concept to an industrial scale, which would have obvious applications for other space missions.
Third, we plan to rely on inflatable structures. Constructed of multilayer fabrics shielded with Kevlar or other strong materials and banded by steel exoskeletons, these structures could provide most of our habitation, storage, and transportation requirements. They would be both lighter and less expensive than traditional spacecraft. A number of companies have done extensive R&D on such inflatable space structures, including Boeing and Bigelow Aerospace, which has even lofted two test modules to low Earth orbit.
Reliance on such technologies will decrease the cost of our operation, but it still will not be cheap. We estimate that establishing a lunar mining outpost and low-Earth-orbit fueling network will cost about $20 billion and take about a decade to put in place. That may sound like a lot, but in terms of complexity it’s comparable to a North Sea oil production complex. And it’s just a third of what the state-owned oil company Saudi Aramco said it will spend on oil and gas projects over the next five years.
We live in interesting times. Right now, the technology, opportunity, and need to undertake such a mission are converging. Global tensions over resources, energy, and the environmental balance will only intensify in the coming years. New technologies may solve some of these problems, but ultimately we must look further afield for answers.
The Shackleton project offers a solution. We seek the boldest and most imaginative managers, policy makers, investors, engineers, and explorers to partner with us and to ignite the Earth-moon economy. It is time for the private sector to take the lead in creating new markets and expanding humanity’s presence in space. Governments cannot and will not do it by themselves anytime soon. Our company is prepared to open up space to those who have the vision, stamina, and wherewithal to make it a reality. Join us!
For more articles, go to Special Report: Why Mars? Why Now?
About the Author
William Stone is an aerospace engineer and explorer. He serves as the chairman of Shackleton Energy Co., based in Del Valle, Texas.