How to mine an asteroid

  • The 2049ers
  • A NASA engineer stands in front of six segments of the James Webb Space Telescope’s primary mirror. Space miners may field the first privately owned space telescopes – and rent them out.
  • See one asteroid to go, please
  • A prototype robot, created by NASA’s Jet Propulsion Laboratory, has 750 steel hooks for feet. These adhere to rough surfaces, preventing bots working in low gravity from drifting away.
  • See Asteroid mining infrasturcture
Date:1 September 2012 Tags:, ,

In April, a group of aerospace veterans and investors announced an audacious venture: a company, Planetary Resources, dedicated to mining asteroids. “Breakthroughs require taking extraordinary risks,” says co-chairman Peter Diamandis. The company, backed by technology trailblazers such as Google CEO Larry Page, movie director and inventor James Cameron, and Microsoft software guru Charles Simonyi, does not expect a fast return on investment. “Within a small number of years, we’ll be flying to asteroids,” says co-chairman Eric Anderson. “But we have a 100-year view for this industry.” By Michael Belfiore

Step 1: Get prospecting
To mine an asteroid, a company such as Planetary Resources first has to find one that promises a good return on investment. But asteroids don’t glitter like stars. They are small, dark and easily obscured by the distorting effect of Earth’s atmosphere. The best way to hunt for them is with a telescope floating in space. At the Washington headquarters of Planetary Resources, chief engineer and company president Chris Lewicki is assembling the components of the first privately owned space telescope, the Arkyd 100 series.

The 20-kilogram spacecraft will be smaller and simpler than any government-funded space telescope. The R12 billion Hubble Space Telescope has a 239-centimetre-diameter primary mirror; Arkyd’s mirrors will be 29 cm wide. Hubble has a wide field of view, as well as other instruments to scan objects in distant space. Arkyd needs only to look in our own solar system for targets. Being small saves money: rockets carrying larger sats could also haul these telescopes as secondary payloads, decreasing launch costs.

Planetary Resources plans to build a fleet of space telescopes to help drive the per-unit cost down to less than $10 million (about R80 million). Having multiple telescopes is insurance in case one fails. “We need to make something in an assembly line,” says Lewicki, a former Jet Propulsion Laboratory Mars mission manager. “We can’t just build one precious jewel that we treat with kid gloves.”

The Planetary Resources team will also rent out the Arkyd 100s, the company’s first stab at making money. Its space telescopes can be used by cosmic researchers or by Earth scientists who want to examine the planet from space at a resolution of about 2 metres per pixel. Planetary Resources hopes to launch the first satellite by the end of 2013; company officials say rental prices have not yet been determined.

Step 2: Assay and stake
Once company telescopes spot a mining prospect, there’s only one way to determine what resources the asteroid contains: get close.

The Planetary Resources team envisages a swarm of prospecting bots heading out to conduct close flybys of near-Earth asteroids (NEAs). “We’re talking about building interplanetary probes at a fraction of the cost (of current models), which requires doing things very differently,” Diamandis says.

NASA has used this form of propulsion twice for deepspace exploration. It uses electricity to positively charge xenon atoms, which are pulled out of the craft by magnets. The repulsive force provides thrust that propels a vessel, building speed over the course of years. It takes a while, but when it gets going the craft can exceed 300 000 km/h.

The asteroids of interest likely will be less than one and a half kilometres in diameter, too small to have appreciable gravity. Spacecraft don’t land on such small asteroids; they dock to them. A spacecraft will slowly approach, getting close enough to barely touch the asteroid’s surface before deploying an anchor. Grappling hooks might just grab a chunk of surface material and float away. A better option is to deploy drills in each landing pad that secure the craft to the surface.

The robot would then analyse the water and metal content of the asteroid and beam the results to Earth. The tool of choice for this assay would be a laser-induced breakdown spectroscopy system, or LIBS. Lasers vaporise surface material so sensors can analyse the light emitted by the resulting plasma to identify elements. The first LIBS to be deployed to another world, ChemCam, is currently en route to Mars aboard NASA’s Curiosity rover.

Step 3: Start digging
The prospecting craft might also tag the asteroid by planting a radio beacon on its surface. According to company officials, the beacon would do more than help future missions get a fix on an asteroid’s location. “Placing a beacon is part of building a case for ownership,” Diamandis says.

A private company’s claim to an asteroid is uncharted legal territory. In the next decade lawyers may have to factor in the presence of private-sector entrepreneurs in the Outer Space Treaty, first signed in 1967 and ratified by more than 100 nations. If it turns out that possession really is nine-tenths of the law, then a simple radio transmitter could help make the miner’s case.

Space miners will prize water more than gold. Its value manifests when it is split into its elements: hydrogen can recharge power cells and be recombined with oxygen to produce energy-rich fuel. Harvesting water in space is cheaper than shipping it from Earth. Every litre, at a weight of a kilogram, can cost tens of thousands of rand to launch. Planetary Resources could profit by selling spaceharvested water to governmental or private spacecraft at a premium, but for less than it would cost to deliver from Earth.

Carbonaceous chondrite asteroids are the best prospects for water. The surface of these so-called C-type asteroids is crumbly, says John Lewis, professor emeritus at the University of Arizona and author of Mining the Sky, the seminal book on the space industry. “You can hold a cube between your thumb and your forefinger and crush it,” he says. There’s no need to burrow; you can just scrape the surface of a C-type asteroid to mine its water.

A swarm of mining bots, clinging with barbed feet to the surface of an asteroid, would slurp up water-laden soil through proboscis-like drills, while others would vacuum the debris left in their wakes. The robot would then pull out the soil, or regolith, and deposit it in a sealed container. The robot would walk, float or crawl to a processor lashed to the surface or floating above it. The processor would heat the regolith to release water vapour, which would be collected into a storage tank.

Space miners face a more difficult challenge when harvesting metal. M-type asteroids, essentially big flying chunks of solid metal, might not feasibly be mined, says Harry McSween, geoscientist at the University of Tennessee and chair of the surface composition group for NASA’s Dawn asteroid probe. Anchoring to such a body would be hard enough – drill-style landing pads wouldn’t work – let alone sawing off a chunk of the asteroid for processing. “When you think about how much energy would be required, it seems pretty unrealistic,” McSween says.

But Lewis figures that some asteroids might be made up of as much as 30 per cent metal, in the form of an iron-nickel-cobalt and platinum-group alloy. “The temptation is to simply use a magnet to pluck the metal grains out of that regolith,” he says.

Some metal-rich asteroids might be worth taking closer to Earth, as close as the Moon, in their entirety. “The concentration of metal is so high that you have to wonder whether you could just bring the whole thing back,” Lewis says. (It’s not so far-fetched; see “One asteroid to go, please”.)

Step 4: Deliver the goods
Space sells, but who’s buying? It remains unclear who will purchase the goods that space miners have gone to such pains to gather.

The most lucrative opportunity might be platinum-group metals, one category of the few space commodities that would be shipped back to Earth. “These materials enable so many different hightech processes that we use,” Lewicki says. Today, platinum-group metals are essential to catalytic converters in petroleum engines, as catalysts in the production of silicone, and in the manufacturing of glass. They are incorporated into hard drives; in spark plugs, where their low corrosion rates allow 150 000-kilometre life-spans; and in medical devices, where they are prized for their biocompatibility.

A 500-ton asteroid with 0,0015 per cent platinum metals – a common percentage – would have three times the richest concentration found on Earth. “To have more of this material will open up economies that we can’t even predict,” Lewicki says.

But most asteroid commodities will only be marketable in a future where ambitious spaceflight is a regular human activity; for example, extraterrestrial depots where spacefarers could top off their fuel tanks and water supplies while on long trips. If there are no such trips, there is no business model.

Similarly, the idea that common metals will be useful in space is predicated on a manufacturing industry that is building space stations and spacecraft in orbit. Assembling structures in space, rather than launching them from Earth, is appealing because it avoids the cost of launch. A lack of orbital construction or the advent of cheaper launch systems could obviate this business.

If space stations are growing food for full-time residents, they could become lucrative markets for more than iron and steel. Asteroid-derived nitrogen and ammonia would be in demand for fertiliser. Such industries are vital if humans are to make their home in space. “We’re talking about technologies that break the umbilical cord to Earth,” Lewis says.

Planetary Resources’ scheme is more than a business plan, it’s a rose-coloured blueprint for supporting space exploration. Its existence speaks to humanity’s drive to explore, to spread, and to support the most audacious of our dreams.

Space miners want two things:
Water
A 7-metre-diameter carbonaceous chondrite (C-type) asteroid can hold 90 000 litres of water, which could be used to make rocket fuel or replenish spacefarers.

Metals
A 24-metre-wide metal (M-type) asteroid could hold 30 000 tons of extractable metals, including R400 million worth of platinum alone. But can a mining spacecraft cut off treasure from these metal objects?

One asteroid to go, please                                                                                                                                    Asteroids could be brought closer to home for study and mining. In an April publication, the Keck Institute for Space Studies, based at the California Institute of Technology, Caltech, looked at how to bring one to lunar orbit. Such a rock could provide an attractive destination for astronauts. “The mission will be a stepping stone into the solar system,”
says study co-leader Louis Friedman.

1. Measure it  A slew of laser radar sensors measures the dimensions of the asteroid. A spacecraft then deploys its high-strength capture bag to the appropriate size. Inflatable arms and securing cables unfurl to enclose the asteroid.

2. Bag it  The spacecraft bags the rock. The finish on the bag’s exterior ensures that the asteroid doesn’t heat up and lose water.

3. Bring it home  The craft makes the long trip back to lunar orbit. The return trip could take six years; mining commences on arrival.

Asteroid mining infrastructure
Orbital transportation hub
A larger, manned space station is an ideal place to co-ordinate flights of cargo, mining gear, and explorers.

Space fuel depot
Spacefarers will need places to restock water and hydrogen for fuel (think space filling stations). Scientists today are working on ways to transfer fluids in zero-g.

Deep-space communication relay
Optical laser communications systems transmit as much data as radios and can use half the power. Planetary Resources is developing a system under contract with NASA.

Our rich solar system
Between 2009 and 2011, a NASA space telescope called the Wide-field Infrared Survey Explorer (WISE) catalogued asteroids in our solar system. It found:

  •  More than 100 000 previously unknown asteroids in the belt between Mars and Jupiter.
  • 19 500 mid-sized near-Earth asteroids.
  • 4 700 large, potentially hazardous asteroids that cross within a cosmically close 8 million kilometres of Earth’s path. (NASA estimates that it has cataloguedonly 30 per cent of them.)

 

Space mining tech
Magnetic rake
There is no need to dig mines to gather precious metals from space rocks. By placing a magnet on each prong of the rake,
loose regolith (asteroid soil) can be combed easily for precious metals in low gravity.

Low-gravity sifters
Old-school gold miners rejoice. In 2009 scientists used a vibration table to shake soil through a sieve to separate the particles that would burn most efficiently in an oven; heated asteroidal material releases oxygen. The system worked in zero-g, simulated by parabolic flights of an aircraft.

Asteroid anchors
With almost no gravity, asteroids won’t be easy to land on, let alone allow for operating drills and other mining equipment. NASA’s Jet Propulsion Laboratory is developing steel “toenails”; Honeybee Robotics is creating screw-in augers to keep space machinery from floating away.

Video: Hear what Planetary Resources has to say about mining asteroids