““There was a vague feeling within the agency (though with several notable exceptions) that direct ascent would eventually be the answer, but no one had worked out the tradeoffs in much detail. Subsequently, as Apollo planning progressed, the question of how to fly to the moon and back loomed ever larger. In the end, the choice of mode was perhaps the single greatest technical decision of the entire Apollo program. The selection was inextricably linked to launch vehicles, spacecraft, facilities, cost, development schedules, and the future of America’s posture in space. Ultimately, the mode question shaped the whole of Apollo. Many possible methods were carefully considered, and a Pandora’s box of problems was opened. At the time, however, technical thinking had not matured to that degree. The United States was just on the threshold of manned space flight, and orbital flights around the earth were in themselves mind-boggling. A program to land men on the moon, 400,000 kilometers away, and bring them safely home was nearly too stupendous for serious contemplation.””
![“I've used the Phoenix Centrifuge to replicate what the body's going to go through on the flight up. I've also done some gravity tests with ZERO-G [a charter-flight service in Arlington, Va., that uses modified Boeing 727s to simulate weightlessness], which went great.” quote by Richard Branson](https://sms4smile.com/quotes/img-quotes/aa1/richard-branson-256_adventure_i-ve-used-the-phoenix-centrifuge-to-repl_903.jpg)
