Editing Spacecraft propulsion (section)

===Interstellar===
{{Main|Interstellar travel}}
Because interstellar distances are great, a tremendous velocity is needed to get a spacecraft to its destination in a reasonable amount of time. Acquiring such a velocity on launch and getting rid of it on arrival remains a formidable challenge for spacecraft designers.<ref>{{cite web | last=Rahls | first=Chuck | date=December 7, 2005 | url=http://www.physorg.com/news8817.html | title=Interstellar Spaceflight: Is It Possible? | publisher=Physorg.com | access-date=2007-07-31 }}</ref> No spacecraft capable of short duration (compared to human lifetime) [[interstellar travel]] has yet been built, but many hypothetical designs have been discussed.