Built for American Airlines, NASA acquired the aircraft in 1974 and used it for test flights from Edwards Air Force Base in California's Mojave Desert and ferry flights to the Kennedy Space Center in Florida.
The Third Era began in earnest in 1981, with the launch of the first Space Shuttle, Columbia, a mostly reusable workhorse designed to ferry astronauts, research experiments, satellites and equipment into Earth orbit.
That is exactly what the President had in mind when he laid out a fresh course for NASA to explore new scientific frontiers and take Americans ever deeper into our Solar System while relying on private-sector innovators working in the competitive free market to ferry astronauts and cargo to Low Earth Orbit and the International Space Station.