The space tourism firm XCOR Aerospace Inc. announced plans in 2008 to launch its private two-seat Lynx space plane. Lynx was expected to fly paying space tourists to an altitude of about 38 miles above Earth, where passengers would experience 90 seconds of weightlessness. The company first estimated flight tests would begin in 2010, with private flights to follow soon after. Many space tourists bought into XCOR's Lynx model for the chance to briefly experience weightlessness at the edge of space. Having paid XCOR $100,000 for a ticket, customer Nael Hamameh thought his flight would come as early as 2011,...