Space architecture of space and a space transportation infrastructure can be accelerated. Virgin Galactic has indicated plans for an orbital craft, SpaceShipThree. The demand for space tourism is one without bound. It is not difficult to imagine lunar parks or cruises by Venus. Another impetus to become a spacefaring species is planetary defense. The classic space mission is the Earth-colliding asteroid interception mission. Using nuclear detonations to split or deflect the asteroid is risky at best. Such a tactic could actually make the problem worse by increasing the amount of asteroid fragments that do end up hitting the Earth. Robert Zubrin writes:
Space tourism since 2009. As an alternative term to "tourism", some organizations such as the Commercial Spaceflight Federation use the term "personal spaceflight". The Citizens in Space project uses the term "citizen space exploration". Many private space travelers have objected to the term "space tourist", often pointing out that their role went beyond that of an observer, since they also carried out scientific experiments in the course of their journey. Richard Garriott additionally emphasized that his training was identical to the requirements of non-Russian Soyuz crew members, and that teachers and other non-professional astronauts chosen to fly with NASA are called astronauts.