Moon mining

As people combust the Earth's supplies of coal and gasoline into clouds of carcinogenic debris, scientists are looking beyond the planet's resources to power the next generation of industry.

"As we keep expanding the amount of energy used, pollution will go up," said Timothy Swindle, a University of Arizona space scientist.

Swindle recently finished creating a lunar resource map locating high-density areas of helium-3, an isotope that could possibly be used to create abundant energy through fusion.

Fusion might be the waste-free energy process of the future, according to Swindle and his fellow UA space scientist John Lewis. When elements such as hydrogen or helium are joined, the bonding creates energy.

"There is enough helium on the moon to power the United States for several hundred years," Lewis said.

Lunar helium originally came from the sun, which sheds its outer layers of gas. "Solar wind" blasts into moon rocks that trap the helium.

The Earth has a relatively tiny amount of the element because its atmosphere and magnetic field repel solar winds.

"It (helium) flows off the planet like water off of a duck," Lewis said.

Fusion produces very little pollution compared with the burning of fossil fuels, Swindle said.

"Helium is a very clean fuel - that's the upside," he said.

But there are some problems to be worked out before governments invest in moon mining: no one has ever built a fusion reactor.

An international group of researchers is constructing a reactor to combine hydrogen, but fusing helium will be a bigger, more difficult project, Lewis said.

Hydrogen is accessible on Earth in the form of water, but scientists predict fusing hydrogen will create radioactive byproducts.

When designing the map, Swindle's team considered factors such as the effects of solar wind and the duration of helium bombardment on certain lunar rocks.

There is about 1 ton of helium for every 100 million tons of dirt on the moon, Lewis said. Because the element is spread so thinly, tremendous strip-mining projects would be necessary to extract it from the soil.

"You'd have to expend an awfully lot of energy digging (dirt) and heating it," Lewis said.

There is debate in the scientific community over whether or not such an energy-intensive process would be worthwhile.

"If I were a betting man, I would bet that this scheme will not happen," Swindle said. But as the planet's supplies of gasoline and coal dwindle, humans need to look into any potential source of energy, he said.

If helium fusion becomes a viable process, scientists may exploit giant planets like Neptune and Uranus. Planetary miners would send hot air balloons to drop into the planets.

As futuristic as the plan sounds, Lewis said most of the technology needed to carry it out already exists. The United States was test-firing rocket engines in the 1950s that could get back to Earth from the giant planets, but such experiments were stopped.

"These plans are sitting yellowing in files," Lewis said, adding that they will be revived only if helium fusion is proven very likely to work.

Gathering solar rays is one alternative plan to fusion that scientists are considering. Some suggest putting enormous solar panels on the moon and beaming energy to Earth in the form of microwaves.

"If any of these things would work, I don't know," Swindle said. "But we're going to need energy from somewhere."

Sarah Spivack can be reached via e-mail at Sarah.Spivack@wildcat.arizona.edu.