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 February 2003, the Space Shuttle Columbia disintegrated on re-entry into the Earth's atmosphere, killing all seven astronauts aboard. After this disaster, space tourism on the Russian Soyuz program was temporarily put on hold, because Soyuz vehicles became the only available transport to the ISS. After the Shuttle return to service in July 2005, space tourism was resumed. In September 2006, an Iranian American businesswoman named Anousheh Ansari became the fourth space tourist (Soyuz TMA-9).) In April 2007, Charles Simonyi, an American businessman of Hungarian descent, joined their ranks (Soyuz TMA-10). Simonyi became the first repeat space tourist, paying again to