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:
Business tourism divided into primary and secondary activities. Primary ones are business (work)-related, and included activities such as consultancy, inspections, and attending meetings. Secondary ones are related to tourism (leisure) and include activities such as dining out, recreation, shopping, sightseeing, meeting others for leisure activities, and so on. While the primary ones tend to be seen as more important, the secondary ones are nonetheless often described as "substantial". Business tourism can involve individual and small-group travel, and destinations can include small to larger meetings, including conventions and conferences, trade fairs, and exhibitions. In the US, about half of business tourism involves attending