Editing Nuclear pulse propulsion (section)

===Antimatter-catalyzed nuclear reaction===
{{Main|Antimatter-catalyzed nuclear pulse propulsion}}

In the mid-1990s, research at [[Pennsylvania State University]] led to the concept of using [[antimatter]] to catalyze nuclear reactions. [[Antiproton]]s would react inside the nucleus of [[uranium]], releasing energy that breaks the nucleus apart as in conventional nuclear reactions. Even a small number of such reactions can start the [[chain reaction]] that would otherwise require a much larger volume of fuel to sustain. Whereas the "normal" [[Critical mass (nuclear)|critical mass]] for [[plutonium]] is about 11.8 kilograms (for a sphere at standard density), with antimatter catalyzed reactions this could be well under one gram.

Several rocket designs using this reaction were proposed, some which would use all-fission reactions for interplanetary missions, and others using fission-fusion (effectively a very small version of Orion's bombs) for interstellar missions.