Science vs. Exploration: A Piggyback Solution?
Harrison Schmitt investigating the unique geology of the lunar surface during Apollo 17, the last manned mission to the moon.
As the drive to explore and colonize the moon switches into high gear, some scientists worry that funding exploration could drain resources away from pure science.
One principle of the upcoming manned missions, said Paul Spudis, of the Planetary Exploration Group at Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, is to “try to understand what is involved in cutting the logistical cord with Earth. Can humans live and thrive off the planet?” Spudis spoke at the February meeting of the American Association for the Advancement of Science, in San Francisco, Calif.
And that is precisely where science enters the picture, contends G. Jeffrey Taylor, professor of planetary science at the Hawaii Institute of Geophysics and Planetology at the University of Hawaii at Manoa. “If you buy into the idea that the important thing is to settle the moon, with plans to go elsewhere, you are stuck with idea that you have to use the resources of space.” For settling the moon and beyond, “we will need to use space resources, and science helps us develop those resources.”
How can science benefit from a drive to live off the land in space? One key goal for a self-sustaining colony is to find minerals for building material, such as aluminum for habitats. The best known source of aluminum ore is on the lunar highlands, where abundant deposits of plagioclase feldspar average 28 percent aluminum oxide, Taylor says. Collecting this feldspar could produce a science spin-off, because the lunar highlands are studded with boulders that are remnants of the ancient lunar crust. Although some of these rocks were studied in Apollo samples, “they have not been sampled in enough detail,” he says.
Artist concept of moon bases that NASA plans to establish in the future.
One of the most promising lunar resources is helium-3, an isotope deposited by the solar wind that is extremely rare on Earth, but considered a prime fuel for fusion reactors, should such devices ever be developed. Extensive studies by Gerald Kulcinski of the University of Wisconsin – Madison and others have suggested that H3 could be exported to Earth, but it could also be used to generate heat and electricity on the moon. Either scenario would require massive extraction of the lunar regolith – the granular material sometimes called lunar soil.
A regolith-mining project would offer an opportunity to resolve questions that arose from study of samples taken during Apollo and the Soviet Luna landings, which show changes in the ratio of nitrogen isotopes in regolith samples of different ages. Because the nitrogen in our solar system was originally created within the sun, dating the regolith could lead to a better understanding of the history of the sun – and the moon itself. Portions of regolith have been overridden by lava flows, Taylor says. “If we can date the lava flow, we know the regolith underneath is older.” Furthermore, extracting regolith for resources would expose layers – allowing a lunar stratigraphy that would be too expensive to be supported as pure science.
The lunar highlands. Recent studies indicate this terrain was bombarded mostly by asteroids – not comets – that were flung into the inner solar system when the asteroid belt was destabilized by migrating giant planets. The Earth was similarly bombarded but geological activity has erased most evidence of the impacts.
Credit: LPL Space Imagery Center
If these dating activities were widespread, they could be integrated into a stratigraphic chronology of the moon’s surface, which could contribute to dating asteroid bombardments – a key question in planetary formation. “Imagine how many layers you would have to look at to build up this kind of ‘tree-ring’ picture of the moon.” Taylor says. “The only way to do that is to have another reason to dig the regolith.”
Volcanism also produces pyroclastic flow—a red-hot movement of granular, ashy material. Lunar pyroclastic flows have a high concentration of iron oxide, so they could be mined for ore, or used directly for radiation shielding for habitats. Preliminary studies suggest that pyroclastic deposits are also enriched in elements that are rare on the moon, including zinc, thallium, chlorine and fluorine. If a moon colony needed to use these elements, the miners could easily document their abundance and distribution, while simultaneously studying physical characteristics of the grains. All of this data could expand our picture of lunar volcanism, further improving our understanding of the satellite’s geologic history.
But not every science goal can easily piggyback on resource exploitation. For example, says Clive Neal, an associate professor of geological science at Notre Dame University, geophysics could suffer. “There will be projects that will be difficult to accomplish” from a single outpost on the moon. The Apollo program found that the moon is shaken about once a year by tremors that exceed magnitude 5, Neal says. Unlike earthquakes, which dissipate within a minute or two, moonquakes can last from 10 minutes to an hour. Global networks to monitor the moon’s internal oscillations would “require landings in different locations,” Neal says. If humans want to have “a long-term presence, we need to understand these, and that requires least two stations, preferably placed at the two poles.”
Although lunar scientists, having benefited from exploration during the Apollo program, seem fairly receptive to the idea of integrating science with resource exploitation, Taylor says scientists and explorers generally work in separate spheres. “You have a whole group that likes to do resource utilization, and another group that does science. Many scientists think everything should be done for science, but that isn’t the only component here. We are going to the moon and Mars to settle, because it helps the country and sparks the imagination, but science could be a great beneficiary. To make the habitats, we will be doing science and resource utilization experiments. Science and the search for resources go hand-hand; there is a very interesting synergism between them.”