Scientists, engineers, and business leaders gathered this week in Houston for the Lunar Exploration Analysis Group (LEAG) Conference held October 25–28 in League City, Texas. Under President Bush’s Moon-to-Mars initiative outlined in January 2004, NASA is faced with returning people to the Moon by 2020. A permanent lunar base may be a staging point for a later journey to Mars. What resources exist and how they might be harvested are of particular importance in this context. This conference brought together experts from different fields to share their ideas.
Science writer Trudy E. Bell reports for Astronomy on what she considers some of the most interesting talks.
Today’s presentations focused on ISRU — In Situ Resource Utilization, NASA-ese for digging in the dirt and living off the land. The economics of ISRU are absolutely compelling for Mars: Every kilogram of something useful (water, fuel, breathable oxygen, etc.) you can manufacture on Mars is worth the cost of launching approximately 55 pounds (120 kg) into low Earth orbit. At the Moon’s distance, the savings are negligible. But if we’re really going to land humans on Mars, many people argue it’s smart to learn how to excavate, extract, and build with raw regolith (soil) and debug operations at the nearby Moon before shipping humans and equipment off to distant Mars.
Three presentations were real eye-openers. First, there was Lawrence Taylor of the University of Tennessee at Knoxville. He characterized himself as “one of those weird people who likes to stick things in ordinary kitchen microwave ovens to see what happens,” for example, making monsters out of Irish Spring soap. He found that lunar soil brought back by the Apollo astronauts melts at 2,467° Fahrenheit (1,353° Celsius) faster than his tea water boils at 212° F (100° C) — and it happens “lickety-split,” he said, within 30 seconds at 250 watts.
The reason is that the lunar regolith is largely glass shards produced when micrometeorites plowed into the soil at tens of kilometers per second, melting the silica sand and rock. So the soil has a lot of pure, elemental iron — so called nanophase iron. Not only is this iron magnetic, it also efficiently concentrates microwave energy. This has made Taylor imagine all kinds of machinery, such as a “microwave lawnmower” that could melt regolith into bricks or glass useful for life on the Moon. Think runways, habitat walls, and glass for optical fibers.
Bruce Damer of Digital Space in Santa Cruz, California, presented another neat paper. He uses video-game engines, programmed with physics, to create real-time simulators. Users can control the engines with a keyboard, mouse, or joystick to see what it’s like to use a bucket excavator or other equipment on the Moon. This could be used for training astronaut-operators and also for learning what kinds of digging machines will work in an airless, low-gravity environment scooping up abrasive, sticky regolith. His company has received 2 years of funding from NASA to develop further an impressive prototype.
Equally fun were demonstrations by Wei-Min Shen of the University of Southern California of what he calls “SuperBot.” These fist-sized, articulated, battery-powered modules spontaneously join together, disassemble, and reshape themselves to perform specific tasks. Think of a child’s “transformer” toy on steroids.
The whole idea is to get beyond special-purpose robots (like the space shuttle’s arm), which lie idle most of the time. Instead, the goal is to create multipurpose robots — or, more accurately, a whole bunch of special-purpose robots with the intelligence to grow legs, sprout wheels, extend into a tether, or support something on a pole as the need arises. Shen and his 10 industrial partners have built prototypes, which they passed around for all of us to handle, and which can be seen in fascinating movies (available at the bottom of this page).
Today’s sessions started with a bang — what amounted to a call to action to make lunar commerce happen. This was the first day of the conference in which the room (seating several hundred) was filled nearly to capacity and proceedings were videotaped. Rick Tumlinson of the Space Frontier Foundation issued a rousing challenge, saying we need to make fundamental decisions: “Where are we going? And why are we going there?”
In Tumlinson’s view, our commitment to returning to the Moon was “not an engineering or scientific decision, but a cultural decision.” The basic question boils down to “Do we go to play?” — with Apollo-style get-there-fast-and-get-it-done one-shot expeditions — “Or do we go to stay?” — where we “treat space as a place” where people will settle permanently?
He says: “You can get a lot more done [scientifically and every other way] if you’re living there than if you’re visiting.” This means private enterprise needs to get involved, which would require new partnerships between NASA and private companies. All parties would share the risks and rewards, so that “we will have left not just flags and footprints, but actual feet — people living on the Moon and Mars.”
Larry Austin, president and CEO of a venture-capitalist firm called Starwalker Group, has invested some $5 billion in 180 companies. He explained that venture capitalists seek to provide seed money, usually less than a million dollars, at the “absolutely raw and startup stage.” Such investors look for a payback in the short term, 3 to 5 years, whereas most of the space community looks at horizons a decade or longer away.
Venture capitalists also seek “absolutely disruptive technologies that will remake an existing landscape and shoulder existing giants aside.” In his view, beaming solar power to Earth from the Moon as microwaves is just one such potential technology.
The big obstacle is the cost to get into orbit or get to the Moon, but the eventual payoff is clear. There need to be interim stages with payoffs, however, to bootstrap financing the ultimate vision. “To the extent that you [engineers and scientists] can close the gap” between a 3-year and a 20-year time horizon, “venture capitalists are willing to share that vision with you.”
Subsequent talks fleshed out the limited energy sources on Earth that are making people look at harvesting solar power from the Moon. (Technical difficulties rule out scientist Peter Glaser’s original concept of solar-power satellites in a high Earth orbit.) Others offered thoughts about how to design dual-use robotic technologies to generate profits during development, citing examples from other high-capital, high-risk projects, such as oil companies’ deep-sea drilling rigs.
NASA Associate Administrator Rex Geveden spoke at lunch about NASA’s Robotic Lunar Explorer Program (RLEP) managed by Ames Research Center. Although the first program, RLEP-1, is the Lunar Reconnaissance Orbiter now being built at Goddard, what RLEP-2 will be is still up for grabs. In general, NASA wants a lunar lander that eventually can support human space flight, although initial missions will be robotic to assess the technology and lunar environment. What risks the abrasive, sticky, electrostatically charged lunar dust poses to any lunar lander or structure remains a big concern.
Moon, Mars, and beyond
Sessions today focused on solar-system exploration. H. A. Thronson from NASA discussed the possibility of using Lagrange point 1 (L1), between Earth and the Moon, as a staging area for future missions. The libration points are where the gravitational fields of Earth, Moon, and Sun are balanced, so anything you place there more or less stays put. L1 is five-sixths of the way directly from Earth to the Moon, where “you’ve climbed out of the Earth’s gravitational well, but haven’t yet descended into the Moon’s gravitational well,” Thronson explained.
The idea is to use L1 as a gas/depot station, human-tended but not permanently manned. Parts stored there could be assembled into a larger spacecraft to continue on to Mars, or a large astronomical telescope. Over time, this depot might grow into a multi-use facility with both government and commercial users, and perhaps even generate revenue.
James Head of Raytheon suggested an L1 depot could store robotic ISRU equipment. Such equipment could be deployed to intercept small asteroids that pass near Earth, to mine them for propellants and other useful materials for continuing on to Mars.
Others want to go directly to Mars rather than establishing way stations at L1 or on the Moon. Robert Zubrin of Pioneer Astronautics argued the most cost-effective approach to exploration would be to land in one spot and send out a hopping vehicle to visit other places. He proposed the “Gas Hopper,” a craft that can either jump 25 miles (40 kilometers) from its takeoff spot or use wings and soar up to 125 miles (200 km) at a time.
He designed the propulsion system to be the simplest possible. In one tank, carbon dioxide is compressed from the thin martian atmosphere, which is 90-percent CO2. In another tank, pellets of magnesium oxide or another material are heated (think of the hot rocks used in gas barbecue grills) to 1,292° F (700° C) — a temperature steel can easily withstand. When the hopper’s ready to take off, the CO2 runs through the hot rocks, causing the gas to expand suddenly. The hot gas is directed out a steerable nozzle, pushing the craft off the surface and letting it soar until it literally runs out of gas.
Zubrin and his colleagues showed film clips of two prototypes they flew some 1,600 feet (488m) this summer in Colorado. (The clips are available here — click on the Gas Hopper press release).
Once on Mars, both science and mining will call for drilling into the surface for water ice, titanium, and other resources. Jose Guerroro of Swales Aerospace showed photos and reported on his company’s progress in designing an ultralow-power drill. It that takes less than 200 watts a day — less power than a kitchen microwave oven uses — to drill 65 feet (20m). At only a couple feet a day, the drill is slow, but this unhurried pace does not melt or alter the sample.
And what would we do with a sample? Mark Berggren of Pioneer Astronautics discussed using sulfuric acid to dissolve martian soils. This process is more efficient than crushing or heating a sample to extract oxygen, iron, and other desired materials useful for ISRU. Even the spent residue, when compacted, produces bricks strong enough to use for buildings.
The last hour of the meeting was a lively open-mike discussion about project priorities, incentives for economic returns, and potential funding sources. Most of the meeting’s participants were convinced that returning to the Moon or getting to Mars is only 20-percent technology — the other 80 percent is political will. These goals require the willingness of NASA, private companies, the public, and worldwide governments to reduce or accept the inevitable risks of pioneering throughout the solar system.