Asteroid mining
Raw resources and minerals could be mined from an asteroid in space using a variety of methods. Even a relatively small asteroid with a diameter of 1 km can contain billions of metric tons of raw materials.
In 2004, the world production of iron ore exceeded 1,000 million metric tons[1]. In comparison, a comparatively small M-type asteroid with a mean diameter of 1 km could contain more than 2,000 million metric tons of iron-nickel ore[2], or two to three times the annual production for 2004. The asteroid 16 Psyche is believed to contain 1.7×1019 kg of iron-nickel, which could supply the 2004 world production requirement for several million years. A small portion of the extracted material would also contain precious metals, although these would likely be more difficult to extract.
In 2006, the Keck Observatory announced that the binary Trojan asteroid 617 Patroclus[3], and possibly large numbers of other Jupiter Trojan asteroid, are likely extinct comets and largely water ice. Similarly, Jupiter-family comets, and possible Near-Earth asteroids which are defunct comets, might also economically provide water. The process of bootstrapping using materials native to space for propellant, tankage, radiation shielding, and other high-mass components of space infrastructure could lead to radical reductions in the cost of this infrastructure.
Asteroid selection
An important factor to consider in target selection is orbital economics, in particular the delta-v and travel time to and from the target. More of the extracted native material must be expended as propellant, and thus less returned as payload, in higher delta-v trajectories. Direct Hohmann trajectories are faster than Hohmann trajectories assisted by planetary and/or lunar flybies, which in turn are faster than those of the Interplanetary Transport Network, but the latter have lower delta-v than the former.
Another important factor is target selection. Currently the quality of the ore and the consequent cost and mass of equipment required to extract the ore is unknown. However potential market for materials can be identified and profit estimated. For example, the delivery of multiple tonnes of water to low earth orbit (LEO) in a space tourism economy could generate a significant profit.[4]
The Near-Earth asteroids orbit are considered likely candidates for early mining activity. Their low delta-v location makes them suitable for use in extracting construction materials for space-based facilities, greatly reducing the economic cost of transporting supplies into Earth orbit.
| Mission | Delta-v |
|---|---|
| Earth surface to LEO | 8.0 km/s |
| LEO to near-earth asteroid | 5.5 km/s.[a] |
| LEO to lunar surface | 6.3 km/s |
| LEO to moons of Mars. | 8.0 km/s |
The table at right shows a comparison of delta-v requirements for various missions. In terms of propulsion energy requirements, a mission to a near-earth asteroid compares favorably to alternative mining missions. Low earth orbit is typically attained by Space Shuttle launches.
An example of a potential target for an early asteroid mining expedition is 4660 Nereus. This body has a very low delta-v compared to lifting materials from the surface of the Moon. However it would require a much longer round-trip to return the material.
Mining
There are three options for mining:
- Bring back raw asteroidal material.
- Process it on-site to bring back only processed materials, and perhaps produce fuel propellant for the return trip.
- Transport the asteroid to a safe orbit around the moon or earth. This allows for all materials to be used and not wasted.
Processing in situ for the purpose of extracting high-value minerals will reduce the energy requirements for transporting the materials. However the processing facilities must then be transported to the mining site.
Mining operations require special equipment to handle the extraction and processing of ore in outer space. The machinery will need to be anchored to the body, but once emplaced the ore can be moved about more readily due to the lack of gravity. Docking with an asteroid can be performed using a harpoon-like process, where a projectile penetrates the surface to serve as an anchor then an attached cable is used to winch the vehicle to the surface, if the asteroid is rigid enough for a harpoon to be effective.
There are several options for material extraction:
- Material is successively scraped off the surface in a process comparable to strip mining. There is strong evidence that many asteroids consist of rubble piles[5], making this approach feasible.
- Asteroids with a high metal content may be covered in loose grains that can be gathered by means of a magnet.[6]
- For volatile materials in extinct comets, heat can be used to melt and vaporize the matrix.[7]
- A mine can be dug into the asteroid, and the material extracted through the shaft. This requires a transportation system to carry the ore to the processing facility.
Due to the distance from Earth to an asteroid selected for mining, the round-trip time for communications will be several minutes or more, except during occasional close approaches to Earth by near-Earth asteroids. Thus any mining equipment will either need to be highly automated, or a human presence will be needed nearby. Humans would also be useful for troubleshooting problems and for maintaining the equipment. On the other hand, multi-minute communications delays have not prevented the success of robotic exploration of Mars, and automated systems would be much less expensive to build and deploy.
See also
- Colonization of the asteroids
- Colonization of Ceres
- Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets
- Space manufacturing
- Space mining
- Space-based industry
- In-Situ Resource Utilization
Notes
- ^ This is the typical amount, however much smaller delta-v asteroids exist.
References
- ^ "World Produces 1.05 Billion Tonnes of Steel in 2004", International Iron and Steel Institute, 2005
- ^ John S. Lewis, "Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets", 1997, ISBN 0-201-32819-4
- ^ F. Marchis et al, "A low density of 0.8 g cm-3 for the Trojan binary asteroid 617 Patroclus", Nature, 439, pp. 565-567, 2 February 2006.
- ^ Sonter, Mark. "Mining Economics and Risk-Control in the Development of Near-Earth-Asteroid Resources". Space Future. Retrieved 2006-06-08.
- ^ L. Wilson, K. Keil, S. J. Love (1999). "The internal structures and densities of asteroids". Meteoritics & Planetary Science. 34 (3): 479–483.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ William K. Hartmann (2000). "The Shape of [[216 Kleopatra|Kleopatra]]". Science. 288 (5467): 820–821.
{{cite journal}}: URL–wikilink conflict (help) - ^ David L. Kuck, "Exploitation of Space Oases", Proceedings of the Twelfth SSI-Princeton Conference, 1995.
Publications
- David Gump, Space Enterprise: Beyond NASA, Praeger Publishers, 1990, ISBN 0-275-93314-8.