The Dyna-Soar design contract was awarded to Boeing on Nov. 9, 1959, and designated the X-20 on June 19, 1962. The Dyna-Soar, designed to be a 35.5-foot piloted reusable space vehicle, had a sharply swept delta 20.4-foot-span wing and a graphite and zirconia composite nose cap and used three retractable struts for landing. Eleven manned flights were to be launched from Cape Canaveral Fla., starting in November 1964. Dyna-Soar's first orbital flight was tentatively scheduled for early 1965.

The X-20 reached the mockup stage. -410 million had been spent on its development, and a cadre of astronauts was training to fly it. However, the U.S. government canceled the program on Dec. 10, 1963, because Dyna-Soar had no viable military mission and was too expensive for a research vehicle.