Mining the skies

September 19, 2017

There are two million near-Earth asteroids in our Solar System, containing vast mineral resources, and, even more vitally, water. Plans to survey them are already underway.

Off-earth mining

Just three kilometres in diameter, asteroid 1986DA is a fairly tiny affair by astronomical standards. Yet it contains astonishing wealth. Using radar, astronomers have discovered 1986DA is mainly made up of iron and nickel.

“Essentially, it is a ball of naturally occurring stainless steel,” says Serkan Saydam, a UNSW expert on the mining of off-Earth objects.

Asteroid 1986DA is also estimated to contain more than 10,000 tonnes of gold and 100,000 tonnes of platinum.

The prospect of such mineral riches excites some entrepreneurs. These visionaries picture a fleet of robot spaceships crossing the Solar System to mine its interplanetary resources. This would also open worlds like the Moon and Mars to human colonisation.

With its vast mining experience, Australia is keen to ensure it is in the vanguard of these operations. Hence the appointment of Saydam as an associate professor of mining at UNSW, where he is putting together a small team of off-Earth mining experts. The work of Saydam’s honours student Georgia Craig on asteroid 1986DA highlights the importance of the careful planning that will be needed in future – and the problems that lie ahead.

Named after the year in which it was discovered, asteroid 1986DA orbits the Sun 75 million kilometres from Earth and is rated by the International Astronomical Union as a Near Earth Object, or NEO. But calculations by Saydam show that 1986DA is still too remote to be mined economically. On the other hand, his research suggests that if the asteroid were half its current distance from Earth, it could be viable to exploit.

That is good news because there are about two million other near-Earth asteroids orbiting the Sun. If we can find a better-placed candidate, it could become a target for mining operations. Hence the activities of companies like Planetary Resources (see ‘Frontier horizon’, above) which is preparing to carry out detailed surveys of NEOs to find one best suited for mining operations.

Asteroids like 1986DA are not the only targets for future missions. Other types of asteroids contain far less mineral wealth, but much more water. That could be crucial, says Saydam. “Water will be our prime source of fuel in space, and finding sources will be a priority. Hydrolysis of water produces hydrogen and oxygen, which can be burned together as fuel, and used in space shuttles and/or satellites. To put it bluntly: water is going to be the currency of space.”

Worlds like Jupiter’s moon Europa, which has a vast ocean below its frozen surface, and Saturn’s tiny Enceladus, which vents water into space, would be good targets but are too remote.

“We will have to find water much nearer to home, and given that we have to start somewhere, Mars is the logical place to begin our hunt for water on another world,” says Sophia Casanova, a geologist and PhD candidate who is now studying off-Earth mining at UNSW. “Finding and extracting water will be crucial for setting up colonies there.”

The trouble is that, while the poles of Mars have ice, they are too cold and inhospitable to provide homes for early colonists. By contrast, Mars’s equatorial region is warmer and more amenable but lacks water – at least on the surface. “That means we will have to seek it underground,” says Casanova, whose research is now focused on finding ways to pinpoint rich deposits of clays and hydrate deposits at lower latitudes on Mars. “There could be some kind of artesian wells, but we have no evidence of their existence as yet. So we will probably have to use hydrate minerals.”

But how can we extract water from rocks? Casanova explains: “You could put your minerals in a chamber and heat them to extract the water. Alternatively, you could use microwave generators that heat the underground to break up the rocks and release the water that way.”

At NASA’s Jet Propulsion Laboratory in California, Saydam’s team has developed models to evaluate multiple off-Earth mining scenarios.

Another practical problem concerns the use of seismic detectors. On Earth, a charge is set off and seismic waves that bounce off subterranean deposits reveal their presence. But as a tool for exploring other worlds, the technique is poorly developed. “Some seismic measurements were taken of the Moon by Apollo astronauts, and that’s about it,” says Michael Dello-Iacovo, a former geophysicist and now a PhD candidate at UNSW. “An early Mars lander was designed to do that but crashed. Now the Mars InSight Mission is being prepared to carry out seismic studies but will not be launched until 2018.”

Seismic waves may behave very differently on asteroids or other planets, says Dello-Iacovo. “There will be no atmosphere, and virtually no gravity, and we have no idea how that will affect seismic wave behaviours. My research is aimed at tackling that problem,” adds Dello-Iacovo, who is spending a year at JPL working on methods for improving our understanding of asteroid interiors.

“We still don’t know if asteroids have solid cores or are just piles of rubble held together loosely,” Dello-Iacovo says. “If the latter, they might break apart if only a small force is applied to them during a mining operation.”

A host of ethical and legal issues also need to be overcome, says Saydam. “What treaties are we going to have to set up to exploit space? And what would happen if we suddenly turned a rare metal like platinum into a commonplace one by bringing huge chunks back to Earth? We could trigger a crash in international metal markets.

“On the other hand, off-Earth mining has the potential to trigger great expansion in the global economy and we must make sure that Australia can influence that through its research capabilities. We also need to make sure we have trained manpower to take advantage of this great adventure.”

– Robin McKie

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