“It is quite possible to build atmospheric vehicles using an antimatter drive. After all, a tenth of a gram of the stuff could power a family flivver to orbit and back. But no machine is perfect, and even that tiny smidgin of antimatter would devastate the countryside if anything went wrong. When antimatter drives first become practical, we can expect treaties banning its use for propulsion within Earth’s atmosphere. There are other potential uses for it on Earth; for example, as an ultimate compact source of energy to power an MHD [magnetohydrodynamic] electric plant. The exhaust product is a high-temperature plasma… MHD power does not have to be used to propel vehicles; it could also take care of those demand surges on a nation’s electrical power grid. Will the treaties ban this use, too? We will risk a guess: yes. We will have other sources of energy from space by that time, and they do not involve the potential destruction of even a milligram of antimatter gone astray. So far as we know, antimatter drives are the ultimate in propulsion efficiency. They may have to wait, however, for those orbital factories.
“As a footnote of interest, Jon Post reminds us that if we ever find so much as a single antimatter molecule of heavier stuff that we did not make — anti-uranium, for an extreme example — it would prove the existence of an antistar in which antihydrogen was cooked into heavier nuclei. This in turn would prove the existence of an antigalaxy. We could communicate with its citizens from a mutually safe distance, but handshakes between us would be a mite hazardous to our health.”
Dean Ing and Leik Myrabo, The Future of Flight (New York: Baen, 1985), pp. 158-159.
Centauri Dreams‘ take: Ponder how far we have to go before we can start talking about practical antimatter propulsion. The challenge, of course, is in making the stuff. Yes, a tenth of a gram would devastate the nearby landscape if a craft carrying it were to crash. But today’s best antimatter producer, the huge CERN particle accelerator in Switzerland, can produce about enough in a year to power a 100-watt bulb for 15 minutes. At present, making antiprotons requires 10 billion times more energy than it produces. None of this should be construed as an argument against antimatter propulsion, but rather a reminder that the real breakthrough will come not from engine design but a host of new techniques in antimatter production, storage and transport.