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A continent spanned: Is cislunar space next?

The new Augustine Commission met for the first time last week (June 17). The one-day agenda was filled with presentations on rocket-building, including reviews of NASA’s current efforts along those lines, followed by briefings on a number of possible alternatives. Suddenly, the space blogosphere was filled with speculation on the possible demise of the new Ares I launch vehicle and its replacement by either a commercial or some alternative Shuttle-derived rocket.

An early focus on rockets is perhaps inevitable, given the cost, schedule and technical issues that the Ares program has experienced. But in fact, all this rocket talk is quite beside the point. The real issue is, as it has always been, “What is the mission?” Why are we going to the Moon? Why should we send people into space? Can’t robotic missions explore the universe more cheaply and easily?

Such questions about the space program are answered repeatedly, but the discussion never advances. Recognizing that I am rushing in where space angels fear to tread, let me give it yet another go.

There are many motivations for a national space program. Scientific knowledge is an important objective, but it is not the only one and perhaps not even the most important one. The Vision for Space Exploration is being undertaken “to advance U.S. scientific, economic and security interests.” The Vision, proposed by the President and endorsed by two Congresses, was carefully crafted to give logical, long-term purpose and direction for expanded possibilities and opportunities in space. In a speech on the Vision given a couple of years after its announcement, Presidential Science Advisor John Marburger said, “Questions about the vision boil down to whether we want to incorporate the Solar System in our economic sphere, or not.”

Here is the problem. Leaving Earth means escaping from a very deep gravity well. It is very costly to lift mass out of this well; current estimates vary widely, but $20,000 per pound to low-Earth orbit is a commonly cited cost for delivery by the Shuttle. As long as we must lift everything we need in space from the surface of the Earth, we are mass- and power-limited. Thus, we are also capability-limited. And under the existing rules of spaceflight, we always will be.

So, let’s change the rules. Rather than lifting all the water, air and propellant we need up from Earth, let’s find and make those commodities in space. Once we do that, our capabilities multiply many fold. We will be able to go anywhere we want, for as long as we want, to do any job or task we can imagine.

Why the Moon? Because the Moon is the closest, most easily accessible place beyond low Earth orbit that has the resources we need. Water is the currency of spacefaring – we need it for life support, energy storage and rocket propellant. The Moon has abundant supplies of both hydrogen and oxygen; no matter what form those two elements may take, we can extract and make these needed commodities from lunar materials.

Making propellant from lunar material allows us to access not only the Moon’s surface, but any other point in cislunar space (the volume of space between Earth and Moon) on a routine basis. This zone is where all our commercial and national strategic assets reside. Rather than building custom spacecraft, launching them on an expendable rockets, using them for a few years and then abandoning them in place, we would be able to create maintainable and extensible space systems. Spacecraft can be refueled in orbit instead of launched whole cloth from Earth. The VSE asks NASA to find and use what’s out there to create a wholly new, sustainable spacefaring capability.

This is our “mission” on the Moon: learn the skills and develop the technologies needed to live and work productively on another world. Creating a space transportation infrastructure is akin to building the first transcontinental railroad; it will open up the frontier of cislunar space. And a system that can access cislunar space will take us to the planets.

NASA’s task is to probe beyond low Earth orbit—opening the space frontier for sustained exploration. The agency’s job is not to industrialize the Moon, but to answer the question, “Can the Moon be industrialized?” This new direction is far removed from the geopolitically driven Apollo template of “flags and footprints.” The multinational fleet of probes scouting the Moon is testament to mankind’s boundless curiosity and a timely reminder that those who explore, excel.

A mission statement must be clear and simple. When the mission is understood, debate about rockets and architectures take place in an information-rich environment. The launchers used and the way mission elements are put together is optimized based on the requirements of the mission. Developing those requirements cannot begin until you know the mission.

One hundred and forty years ago, the mission was understood — to span the continent with a transportation system, opening up the frontier to development.  That mission created a modern industrial nation. We seek to do the same with cislunar space. And then, the planets.

Carnigie-Mellon's Scarab rover: Prospecting for resources

Last time, I outlined some of the basic principles of lunar resource utilization.  The Moon is our nearest source of material resources in space and learning how to extract what we need from the Moon is a key skill in our expansion into the Solar System.

All this is very well and good, but how do we go about using the resources of the Moon and of space in general?  Many people tend to think of huge industrial factories, similar to oil refineries, built on the Moon, with large mining communities similar to those depicted in the movie Outland.  In fact, the beauty of space resource utilization is that it’s possible to start very small and build up capability with time.  The “factory” needed to produce a metric tonne of oxygen on the Moon is the size of a typical office desk.

Mining is a very old and venerable field and has some simple precepts.  First, you must find and characterize the prospect.  Next, you need to understand the concentrations and physical states of the “ore body” that you wish to mine.  Then you must collect the feedstock, convey it for processing, extract the desired element or compound, discard the waste and store the product.  For lunar mining, we are now in the process of finding and characterizing the prospect through remote-sensing and mapping of compositions from space and analysis of returned samples.  This characterization has been going on for many years, giving us a first-order understanding of the compositions and physical states of lunar materials.

The Moon is rather ordinary in composition, having a crust (like the Earth) rich in oxides of aluminum, iron, and silicon.  The oxide portion is key: the Moon is over 40 % by weight oxygen.  This oxygen is tightly bound to its host metals and breaking these chemical bonds is one way to produce oxygen, which serves both human life support (air to breathe) and transportation (oxidizer for rocket propellant).  A variety of processes can accomplish these tasks, including electrolysis (melting the soil into a liquid and then passing an electrical current through it) and chemical reduction (using hydrogen or fluorine brought from Earth as a reducing agent).  None of these techniques are in any way “risky” in a technical sense – reduction as a chemical process dates from medieval times.  Abundant solar energy provides virtually unlimited power; some areas near the poles of the Moon are in near-constant sunlight.

The “long pole” in the tent is getting started.  Right now, the architecture for lunar return has no requirement or provision for resource utilization.  NASA’s efforts to date have focused on rocket-building and planning for scientific sortie missions.  Yet learning how to gather, process and use the resources of the Moon is major goal of the Vision for Space Exploration.  The idea is to use what we find in space to create new capabilities.  This goal has the promise of freeing us from the “tyranny of the rocket equation” – we would no longer be mass and power-limited in space.

The key to bootstrapping this capability is the judicious use of robotic precursor missions.  Robotic spacecraft are now orbiting the Moon, mapping the distribution of elements such as hydrogen and ascertaining the nature of the environment near the poles.  The next steps are to measure the composition and physical properties of the polar deposits from the surface; this requires soft-landers capable of landing payloads on the order of a few  to tens of kilograms.  Small surface rovers would be able to map out the elemental concentration of volatiles and determine the best places to mine.

After the prospects are mapped, we must experiment with different techniques for harvesting and processing.  Again, this work can be done by modestly sized robotic missions, landing small excavators and trucks (Mars rover-sized) and using laboratory bench-scale processing equipment.  Landing and experimentation with this equipment will allow us to find out which techniques are most effective, what processing methods use the least amounts of energy and have the highest yields, and determine where the choke-points are in the processing and production stream.

These small initial steps allow us to begin extracting and storing resources immediately.  Over time, we can increase these capabilities such that when people finally return to the Moon, they have at their disposal a cached accumulation of consumables, including air, water and rocket propellant.  In effect, we are creating the initial phases of self-sufficiency even before human arrival through the emplacement and use of automated, robotic infrastructure.

No one knows if lunar resources can be extracted and used in the manner described here.  But that’s why we’re going to the Moon in the first place – to answer these questions.  We are using the Moon as a laboratory to learn how to live and work productively on other worlds.  The skills and technologies developed here will serve us well wherever else we go in the Solar System.  And the sooner we get started on this path, the sooner we will develop a true spacefaring infrastructure.