Aboard the International Space Station this week are five astronauts and one "space flight participant" — to use NASA's words. Mark Shuttleworth is the world's second space tourist. The 28-year-old South African Internet businessman is paying $20 million for the trip. Advocates of space tourism see Shuttleworth's voyage as the long-overdue dawning of a new era. For All Things Considered, David Kestenbaum reports.