It reads like science fiction but the objective of at least two private US companies, Planetary Resources and Deep Space Industries is to send spacecraft to mine asteroids for minerals that are becoming scarce here on Earth.
These minerals have industrial uses but are also used in food production. A second reason to mine asteroids is to excavate water rich minerals and other volatiles which after processing can be used as rocket fuel.
The scarcity of some industrially useful metals such as phosphorous, gold, zinc, antimony and copper, as well as several other more exotic metals, is the result of Earth’s early geology.
Earth has a much stronger gravitational field than low mass asteroids. This means that heavier elements sank into the depths of its molten core during the Earth’s formation, leaving the upper crust relatively metal poor.
It is estimated that the supply of metals such as gold and zinc will be exhausted within the next 80 years. The Earth and asteroids accreted from the same starting materials during the Solar System’s formation but asteroids are typically 50 metres to 500 kilometres across and so have very small gravities and hence the minerals are much nearer the surface and so potentially easier to access than on Earth.
As the price of these minerals rises the economic case for asteroid mining becomes more compelling.
Ice and water extracted from asteroids can be used for human consumption and for fuel.
The hydrogen and oxygen produced by electrolysing water are very efficient rocket fuels. Thrusting spacecraft out of the grip of the Earth’s gravity and into orbit is very expensive and requires vast amounts of fuel, but once in space, remote from Earth’s gravity, fuel consumption reduces dramatically.
Planetary Resources note that it takes 50 kilograms of propellant to deliver 1kg of cargo into Low Earth Orbit (LEO, 300km above the surface), after that 4kg of propellant takes you a further 35,000km (Geocentric Orbit, GEO) and 2kg more takes you the next 300 million kilometres.
The point is, each kilogram of the 4kg of fuel to get from LEO to GEO needs 50kg of fuel to get to LEO and each of the 2kg to go into deeper space needs 4kg to get to GEO and each of those needs 50kg to get to LEO – increasing the launch loads increases the fuel requirement exponentially.
The answer is asteroids. By using asteroids as refuelling stations huge savings in launch costs could be made since bulky and heavy fuel payloads will no longer be required and interplanetary travel would be much more feasible.
Potential asteroids to be mined are currently being identified and categorized, for example, there are water rich asteroids (extinct comets) and asteroids which contain significant deposits of carbon and phosphorous (constituents of fertilizers for food production).
Other asteroids are metal rich, particularly platinum, nickel and cobalt. Of the many thousands of asteroids, 12 are identified as being accessible using today’s technology.
The idea of mining asteroids is not fantasy. In 2005 the Japanese landed a spacecraft on asteroid 25143 Itokawa, a tiny asteroid 500 metres across which has an elliptical orbit ranging between 0.9 to 1.7 times the Earth’s distance from the Sun. The spacecraft dug into the asteroid dust and returned samples to Earth.
Both of the companies, Deep Space Industries and Planetary Resources are managed by a phalanx of highly qualified scientists and engineers.
For example, Chris Lewicki of Planetary Resources was the Flight Director for NASA’s Mars Spirit and Opportunity surface rovers and the Surface Manager for the Mars Phoenix Lander. NASA, in recognition of his services named an asteroid after him, 13609 Lewicki.
Planetary Resources have already tested their innovative technologies by launching a spacecraft from the International Space Station. The websites of both companies exude an exuberance and spirit redolent of the movers and shakers of Britain’s Industrial Revolution in the19th Century, although Planetary Resources liken themselves to the East India Company in the 1600s who boldly ventured to lands which at the time were unimaginable distances from Europe.
Currently, these companies are in the research and development stage and so rely heavily on donations, however they appear to be well funded. Planetary Resources for example is backed by Google billionaires Larry Page, Eric Schmidt and film maker James Cameron amongst others.
Private companies such as Planetary Resources and Deep Space Industries and the work they do could well be laying the foundations for the future of the entire human species and bringing us closer to regular interplanetary travel.(ROGER HANSON)
Link: http://www.stuff.co.nz/science/74681872/asteroid-mining-already-being-planned
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