© 1975-1979, 2008 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization, First Edition, Xenology Research Institute, Sacramento, CA, 1979; http://www.xenology.info/Xeno.htm

19.1.2  Energy Storage and Mining Techniques

Imagine a chunk of dense grey metal, roughly the size of a fountain pen and weighing less than half a kilogram. Its continuous energy output is nearly 4 megawatts of power, falling off to 2 megawatts after two months have elapsed. Even after a year it is putting out as much heat as a large domestic furnace.

This substance actually exists!⁸¹ It is the radioisotope Californium-254, an element known to human science but which has never been produced in macroscopic quantities. If aliens have done so, the possibilities for exploitation of such a compact energy source are staggering -- high performance light-weight electric vehicles, portable kilowatt-power radio broadcasting stations, hand-held megajoule laser rifles...the list is virtually endless.

Robert Forward has suggested that it might be possible to build "subcritical nuclear reactors."²⁰¹⁴ Normally, atomic fission piles must be made of a certain minimum size. This is because the neutrons which initiate fission reactions arise randomly from within the fissionable material itself. But there is some evidence that nonstatistical means for controlling neutrons may exist.²⁸²² Thus controlled, neutron emission would no longer be random and vastly improved efficiencies should be possible. Tiny, portable fission reactors could probably be built to service aircraft and surface vehicles. Reactors using nonradioactive lightweight metals such as beryllium or lithium would also be possible.

There are a number of other unusual energy sources. Although we don‘t ordinarily think of it as such, planetary rotation is an excellent storehouse of energy. The spinning Earth, if slowed to a dead stop, would free about 2.6 x 10²⁹ joules -- enough to power human civilization at its current rate of consumption for a billion years into the future. Sol, if similarly halted, would liberate 1.2 x 10³⁶ joules.

An even better place to store huge quantities of energy is in rotating chunks of ultradense matter. Hawking black holes would be ideal for the purpose. A 10¹⁶ kg HBH would be heavy enough not to evaporate very energetically (only about 16 kilowatts spontaneous), light enough to utilize in a space-based power storage station (mass equivalent to a 16-km-wide asteroid), and stable enough to serve as power center for a long-lived civilization (lifetime about 10¹² eons). Its radius would be subatomic, about 10^-11 meters, and energy could be stored and retrieved by imparting rotation via electromagnetic field coupling. Spun up to a maximum operating tangential velocity of 10%c, synchrotron radiative losses from the system would be extremely low. The spinning HBH could store up to 2 x 10³⁰ joules of energy -- enough to power present-day humanity for 9 billion years.

A wide variety of new mining techniques can also be imagined. In one of his science fiction novels, Larry Niven speculates on the possibility of specially bioneering organism which he calls “mining worms“:

A mining worm is five inches long and ¼-inch in diameter, mutated from an earthworm. Its grinding orifice is rimmed with little diamond teeth. It ingests metal ores for pleasure, but for food it has to be supplied with blocks of synthetic stuff which is different for each breed of worm -- and there's a breed for every metal... .What breaks down the ores is a bacterium in the worm's stomach. Then the worm drops metal grains around its food block, and we sweep them up.²³¹

This idea is not at all farfetched. Various plants and animals are known to be "hyperaccumulators" of specific minerals or metals. For instance, the so-called “copper flower“ native to Zaire has a dry weight that is 1.3% copper.²⁸⁵² The subject of artificial mining organisms has already been discussed in Chapter 16.

Arthur C. Clarke proposes that subterranean automated probes -- “subterrenes,“ as he calls them -- be designed to explore and exploit at least the entire crustal region of any terrestrial planet. Burrowing through solid rock using powerful rf radiation, ultrasonics, or laser heating, subterrenes could circumnavigate whole worlds down to depths of hundreds of kilometers, searching for deposits of rare minerals and lodes of precious metals.²⁸⁴¹ Says Clarke:

All the scientific observations and collection of samples could be done automatically according to a prearranged program. With no crew to sustain, the vehicle could take its time. It might spend weeks or months wandering around the roots of the Himalayas or under the bed of the Atlantic before it headed for home with its cargo of knowledge.⁵⁵

The main problem with materials mined from planets is that they lie at the bottom of a deep gravity well. As we have already seen, space is the proper environment for stellar and galactic civilizations. So it is far more economical for such cultures to mine material that is already aloft.

Asteroid mining is within the abilities even of human Type I technology. The late Dandridge M. Cole and Donald W. Cox once calculated that to move a 3 billion ton iron meteoroid from the asteroid belt to a parking orbit around Earth would require about 8.4 x 10¹⁸ joules of energy.⁵⁶³ (Recent analyses put this figure slightly higher.²⁸⁴³) This is the same as two hundred 100-megaton H-bombs assuming a 25% propulsive efficiency.

According to Cole and Cox, a small atomic bomb would be set off near the asteroid's surface to form a crater. Subsequent blasts could then be fired in this crude thrust chamber. Another proposal offered by Gerard O‘Neill is to use a “mass driver“ to propel the flying mountain of metal.²⁷¹⁰ Using electromagnetic forces small pieces of the asteroid would be flung from the driver as reaction mass, propelling the giant mother lode to Earth. A prototype mass driver has already been constructed and was successfully tested at the Massachusetts Institute of Technology in 1977.

Last updated on 6 December 2008