Towards the end of the Apollo Space Program in 1972, NASA began the process of developing the concept of re-usable rockets in the form of a Space Shuttle or space transportation system (STS). Such a concept would involve a vehicle that could launch as a rocket but could re-enter the Earth’s atmosphere and land like a glider, as a more technologically advanced alternative to the disposable rockets of the past.
NASA decided that the Space Shuttle would consist of an orbiter attached to solid rocket boosters and an external fuel tank, as this was considered the safest and most cost-effective design. Instead of the ablative heat shields – used during the Apollo missions – that would burn away upon re-entry to the Earth’s atmosphere, Rockwell International as the chief Shuttle designers purported to cover the vehicle with multiple insulating ceramic tiles. These could effectively absorb the heat of re-entry and enable the same Shuttle to be used again on future missions.
In a step to test the aerodynamic design of the new Space Shuttle upon re-entry and landing, Enterprise (OV-101), as the first Space Shuttle Orbiter was built in 1976.
Enterprise, was rolled out of Rockwell’s Air Force Plant 42, Site 1 Palmdale California assembly facility on Sept. 17, 1976. On Jan. 31, 1977, She was transported 36 miles overland from Rockwell’s assembly facility to NASA’s Dryden Flight Research Facility at Edwards Air Force Base.
Although not actually equipped to go into outer space, Enterprise took part in the approach and landing test program (ALT) at the Dryden Flight Research Facility. Here she demonstrated that by design, a Shuttle could glide into the atmosphere and land like an aeroplane.
The 9 month-long ALT program was conducted from February through to November 1977 and consisted of numerous manned and unmanned test flights in which the vehicle was launched from a Boeing 747 mid-air. At this point, the astronaut crew separated the spacecraft from the SCA and maneuvered to a landing at Edwards Air Force Base. Out of five flights, the first four landed on a dry lake bed; in the fifth, the landing was on Edwards’ main concrete runway under conditions simulating a return from space. The last two free flights were made without the tail cone, which is the spacecraft’s configuration during an actual landing from Earth orbit.
Ground tests were also used to test the orbiter systems of the Shuttle. All orbiter systems were activated as they would be in atmospheric flight.
Such tests demonstrated the orbiter’s overall ability to approach and land safely with a minimum gross weight and using several center-of-gravity configurations. The ALT program was therefore largely instrumental in preparing for the first manned orbital flight.
Finally, after several further years of testing the Shuttle’s orbiter, main engines, external fuel tank and solid rocket boosters, the Space-Shuttle design was finally sufficiently advanced enough for space flight. This resulted in the creation of the Orbiter Columbia which became the first Space Shuttle to fly into the Earth’s orbit in 1981, closely followed by Challenger in 1982, Discovery in 1983, Atlantis in 1985 and Endeavour in 1991.