21.4.1 - Economic Viability of Interstellar Cargo Transport

Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization

First Edition

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

An astonishing fallacy that appears repeatedly in the literature is the assertion that interstellar freight costs must be so prohibitive that not even gold, diamonds, radium ingots, or complex microelectronic devices would be worth their weight in trade between the stars.⁵⁵³ This notion often is used to demonstrate that trade in any commodity other than knowledge (data) is a futile and cost-ineffective endeavor. Fortunately, this simply is not so.

Two civilizations inhabiting different star systems can trade in bulk goods for comparatively little energy. Each culture, for example, may erect a giant mass driver which is used to dispatch cargos as well as to receive them. Here’s how such a transport system might work.

As the consignment arrives at Solar System A, traveling at its normal operational velocity (say, 50%c), it is swallowed by the giant mass driver. The driver decelerates the robot cargo vessel by coupling with magnetic fields. Kinetic energy is recovered and converted to potential (stored) energy. (See Chapter 19 for some ideas on how this might be done.) The cargo ship, now at rest, is unloaded and filled with goods ordered by the inhabitants of Solar System B. Finally, using the energy stored during the craft’s arrival (plus a small bit of local energy to balance conversion losses), the ship is accelerated back up to 50%c and shoots out the barrel of the giant mass driver bound for B. If A and B are 10 light-years apart, each trading cycle should require only about 20 years.

The total energy which must be handled during each cycle phase is about 3 x 10²⁴ joules, which looks like a job for a Type II civilization.* However, most of this energy is recovered because a mass driver constructed by advanced aliens may incorporate superconductive windings and ultra-high-efficiency storage devices. So what is the cost, in terms we can understand? Assuming roughly $0.01/kilowatt-hour, the mass driver regenerative system must be 99.998% efficient to achieve costs comparable to the space shuttle (about $1000/kilogram) -- but between stars. If 10%c missions are acceptable, the required efficiency drops to 99.93%; if 1%c missions are sufficient, only 92.6% efficiency is needed. And large-scale power generation in space may permit energy to be produced vastly cheaper than on Earth’s surface today. If the price of energy drops by three orders of magnitude, then the required efficiency for the 50%c mission is only 97.7% and for the 10%c mission a mere 23.8%. With sufficiently refined technology, interstellar bulk trade in raw materials and manufactured items may actually be cheap!