The space shuttle

The US Space Shuttle was intended to make space travel cheap, easy and routine.

Space Shuttle “Atlantis” on display at the Kennedy Space Center

In the spring of 1969, just as America was about to land astronauts on the Moon, President Richard Nixon appointed a NASA panel under Vice President Spiro Agnew to make recommendations for the future direction of manned spaceflight. When the Space Task Group issued its report in September, it was optimistically ambitious. Recognizing that the Apollo approach, using one-shot expendable booster rockets and space capsules, was too expensive and wasteful to be viable in the longterm, the panel recommended that NASA focus on producing a space vehicle that was completely re-usable and would be capable of launching a crew and payload into orbit, performing missions in space, then returning to Earth to be refueled and launched again. Once a workable shuttle was in place, it could be used to construct a permanent orbiting Space Station, which would in turn function as a stopover point for future manned missions to the Moon and, eventually, to Mars.

Nixon, however, was not interested in something so grand as a Mars mission. He had already agreed to the Skylab Project, which was a cheap and temporary space station cobbled together from leftover spare parts and vehicles from the Apollo program, but Nixon also knew that the entire Moon project had been mostly a Cold War political stunt with the sole aim of beating the Russians and had no real scientific goals, and he was not ready to commit the massive funding that a real program of science and space exploration would cost. But one part of NASA’s outline did appeal to him (as well as to the Air Force, which also weighed in): a reusable space shuttle could be used to deliver satellites (military, civilian and commercial) to space cheaply and reliably. So Nixon approved funding for the Space Shuttle program (originally designated the “Integrated Launch and Re-entry Vehicle”) in 1970. Meanwhile, NASA’s budget was slashed to just a third of what it had been during Apollo.

NASA had already made preliminary designs for such a “space shuttle”, and in total at least 30 different design proposals were considered. Many of these were based on the “Dyna-Soar” concept, a reusable “space plane” that had earlier been the subject of study by the Air Force but had never been built. In many early designs, this “orbiter” module would be carried aloft by a larger reusable “space truck” that would not enter space itself but would carry the orbiter to the outer atmosphere where the “truck” would detach and return to Earth. As NASA’s budget continued to be cut, however, this concept proved to be too expensive, and design work focused on using an expendable single-shot booster stage to carry the orbiter into space.

Eventually, a design was selected in January 1972. The orbiter module would be carried into space by two external solid-rocket boosters, supplemented by the vehicle’s main engines. During launch, the shuttle engines would be fed liquid hydrogen and liquid oxygen from a large external fuel tank. Once the shuttle was on its way, the empty external fuel tank fell off and burned up, while the solid rocket boosters would descend by parachute into the ocean, to be recovered, refurbished, and re-used. After its space mission was complete, the orbiter would again fire its main engines to de-orbit and return to Earth to make an unpowered landing on a conventional airstrip, like a glider, to be refurbished for another flight.

The first orbiter to be built had no functional engines: it was intended solely for flight and landing tests and would be carried aloft by a specially-modified Boeing 747 airliner. Original plans called for the test orbiter to be named “Constitution”, but a letter-writing campaign from TV Star Trek fans led to a name change, and the orbiter was dubbed “Enterprise” instead. Ironically, the real NASA “starship Enterprise” was not capable of spaceflight and never left the atmosphere. But in a series of tests, Enterprise demonstrated that the Shuttle design was capable of making unpowered landings at orbital re-entry speeds.

The Space Shuttle was one of the first flight vehicles to use a computerized “fly-by-wire” system. In this arrangement, there are no hydraulic lines for the control services: instead, the inputs from the pilot’s control stick are fed to a computer, which then manipulates the ailerons and tail rudder to produce the desired effect. The Shuttle had five redundant computer systems for flight control. Similar fly-by-wire systems were adopted by the military for use in high-performance fighters.

Another technical challenge centered around the heat shield. Objects that enter Earth’s atmosphere are subject to immense heat, several thousand degrees, caused by friction with the air. In the Mercury, Gemini and Apollo spacecraft, the crew was protected from this heat by an “ablative heat shield”, a honeycomb of metal and resins that boiled off during re-entry, carrying the heat away with it. Since this process destroyed the shield, it could not be employed on a re-usable shuttle, and a new solution had to be found. It came in the form of special ceramic tiles that were extremely efficient insulators. These came in two versions: the higher-temperature black tiles were used on areas where the heat would be particularly intense, such as the nose, belly and wing edges, while the rest of the shuttle was covered with lower-temperature white tiles.

The first flight-capable orbiter, named “Columbia“, was completed in 1979 and made its first spaceflight in April 1981 with a crew of two astronauts. With this successful test, the shuttle system became operational. Over the next three years, three more orbiters entered service: Challenger, Discovery, and Atlantis.

In NASA’s original vision, the primary purpose of the Space Shuttle was to ferry personnel and materials for the construction of a permanent orbiting Space Station which would serve as a waystation for missions to the Moon and beyond. As NASA’s budget continued to be cut and people lost interest in the space program, however, plans for a space station were dropped, and the Shuttle’s primary mission morphed into delivering satellites to low-earth orbit. This in turn led to criticism of the entire program, as skeptics pointed out that it was cheaper and easier to use expendable rockets for satellite delivery, and without the Space Station the Shuttle had no good reason for existing. Nevertheless, NASA worked with Canada to develop a remotely-controlled robotic arm that was capable of plucking satellites out of the Shuttle’s cargo bay and placing them into orbit. Congress also demanded that the Defense Department launch nearly all its larger satellites (for surveillance, weather, and navigation) on board the Shuttle, and the Pentagon quickly became NASA’s most important customer. An entire new Space Shuttle launch facility was constructed in California specifically for military missions.

In January 1986, the shuttle Challenger was destroyed when a solid rocket booster malfunctioned in unusually cold conditions, killing the crew and halting the US space program for several years. When flights resumed, a new orbiter, named Endeavour, replaced the lost Challenger. Then, in 2003, another shuttle was lost when Columbia burned up on re-entry after being struck on takeoff by a piece of the external fuel tank’s foam insulation.

By the time of the Columbia accident, however, the Shuttle program was already on the way out. Despite some notable successes, it was still flying with 1970s technology and had never lived up to its advertising in either cost or performance. Even when construction was begun on the International Space Station in 1998, it was the Russian Soyuz family of spacecraft that were the real workhorses. The last Space Shuttle mission, flown by Atlantis, was in July 2011.

After their retirement, the remaining orbiter vehicles were parceled out to museums. Enterprise, which never flew in space, was first placed on exhibit at the Smithsonian’s Udvar-Hazy Center in Washington DC before being moved to the USS Intrepid Museum in New York City. Discovery replaced Enterprise in the Smithsonian in 2012. In 2013, Atlantis was placed on display at the Kennedy Space Center in Florida. And in 2012, Endeavour was delivered to the California Science Center, where she was housed in a temporary hangar for viewing while a new permanent exhibit hall was being constructed.

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