http://www.physorg.com/news64499584.html
NASA scientists believe that, once a few technical hurdles are worked out, they can power a space ship using positrons. Ignoring the obvious problem of storing and transporting antimatter, positrons (anit-electrons) generate gamma radiation of a far lower energy level, possibly low enough to make it feasible to use antimatter to power manned space flights. They expect that such a ship could safely transport a person to Mars in 45 days. This would require creating, and storing, 45 milligrams of positrons. They feel confident that a storage system can be invented that won't annihilate itself.
[Edit: that should read 5-milligrams, not 45 milligrams]
NASA scientists believe that, once a few technical hurdles are worked out, they can power a space ship using positrons. Ignoring the obvious problem of storing and transporting antimatter, positrons (anit-electrons) generate gamma radiation of a far lower energy level, possibly low enough to make it feasible to use antimatter to power manned space flights. They expect that such a ship could safely transport a person to Mars in 45 days. This would require creating, and storing, 45 milligrams of positrons. They feel confident that a storage system can be invented that won't annihilate itself.
[Edit: that should read 5-milligrams, not 45 milligrams]