This year will see both the end of space flights by NASA’s Shuttle fleet and the thirtieth anniversary of the first orbital mission by this historic spacecraft. Our coverage of these milestones begins with an overview of the project’s chequered history.
Ascending to orbit: Shuttle Orbiter Columbia rises skyward (Image credit: NASA)
In the glory days of the Space Race, the public avidly followed the exploits of astronauts. Heroic rocket jockeys were strapped into tiny capsules mounted on rockets, often converted nuclear missiles, and blasted into the wild blue yonder on live TV. Things were different in the early 1970s; through hard work, brains and guts NASA astronauts were walking on the moon in what seemed like an effortless Space Race victory yet nobody cared. NASAтАЩs budget was savagely cut down and earlier and costly plans forbases on the Moon and flights to Mars were shelved. The space programme was going into terminal decline.
Management at NASA saw a way forward. Satellites were proving vital for all manner of tasks, from predicting the weather to relaying TV around the world. It was very expensive to place a satellite into orbit as their launch vehicles, expensively crafted rockets, were thrown away in the course of each flight. Imagine how expensive air travel would be if the whole airliner was thrown away after its first landing! What if a reusable vehicle for carrying cargoes to orbit could be developed? It could fly into space many times, massively cutting costs in the process. Once established, these craft would be shuttling between Earth and space several times per month, and would open a much wider range of possible space projects, including giant space telescopes, space stations, moonbases and Mars landings. Within a couple of decades, a flight to low earth orbit by Shuttle would cost much the same as a first-class ticket on a transatlantic flight
In 1969 NASA asked four industrial contractors to supply concepts for a Space Transportation System or Space Shuttle (note that this never received a proper name from mythology like the preceding Mercury, Gemini and Apollo projects: NASA wanted to show that this was a hard-headed piece of necessary infrastructure, not some flight of fancy). Money was tight and this forced compromises with effects which had lasting effects. Early shuttle concepts were completely reusable, two similarly-shaped but differently-sized winged craft would have been launched connected together piggy-back fashion. Each would have been piloted by astronauts. The larger one, the booster (about the size of a Boeing 747) would have carried the smaller orbiter halfway to orbit before separating to fly home for a runway landing. Although potentially very economical to run, this concept was unaffordable with the development budget at hand. A complete Space Shuttle as eventually developed comprises four components, a large disposable (but cheap) External Tank (ET) for propellants, two reusable Solid Rocket Boosters (SRBs) and the aeroplane-like Orbiter.
An overhead view of a Shuttle being prepared for launch. The cockpit, living quarters and experiment operator’s station are all located in pressurised crew module in the forward fuselage. (Image credit: NASA)
At launch the shuttle Orbiter is attached to the 47m (154 ft) tank which carries 720 tonnes of liquid hydrogen and oxygen for the three main engines at the rear of the Orbiter. These fuels must be kept very cold so the tank is coated in a 2.5 cm (1 inch) thick coat of spray-on foam insulation. Unbelievably use of this this foam later led to the Columbia tragedy. The OrbiterтАЩs engines are not sufficient to push the craft into orbit, so two 45m (147 ft) long solid-fuel rocket boosters are attached to the side of the tank.
All shuttle missions are launched from the Kennedy Space Center in Florida. There are two Shuttle launch pads, Complex 39A and 39B, built originally for the Apollo Moon missions. At launch the 4.5 million lb (2040 tonne) spacecraft rises skyward on seven million lb (31MN) of rocket thrust. Two minutes after launch, the SRBs€а are discarded at an altitude of 45 km, descending under parachutes to the sea to be€а recovered and reused. The ET is discarded about 70 miles (113 km) above the Earth, falling on a planned trajectory to a fiery fate. Within 8 minutes from take-off, the Orbiter has reached its orbital speed of 17 500 mph (7.8 km/s).
Fact and fiction meet as one Enterprise encounters the crew of another Enterprise. (Image credit: NASA)
Approved in 1972, the project initially made rapid progress. On 17 September 1976, NASAтАЩs first Space Shuttle Orbiter was unveiled to the public. Originally to be named Constitution, when the gleaming white spaceplane was rolled out of the hangar it bore the name Enterprise on its wings and side. This was the result of a campaign by Star Trek fans to bombard the White House with letters demanding the name change. Actors Deforest Kelly, George Takei, James Doohan, Nichelle Nichols and Leonard Nimoy plus Star Trek creator Gene Rodenberry were among the VIPs in the crowd.
The closest Enterprise ever got to space was sitting on the launch pad for tests in 1979. (Image credit: NASA)
When rolled out, Enterprise was not fitted with engines or Thermal Protection System (TPS) tiles as they were not ready yet. Both TPS and Space Shuttle Main Engine (SSME) proved more difficult to develop and maintain than anyone expected. The SSME design still represents the pinnacle of liquid fuelled rocket engine technology. There have been bigger engines of higher thrust (the Saturn 5тАЩs F1 comes to mind) but for its weight, the SSMEтАЩs performance is superlative. Most importantly, every other rocket engine is designed to be used once and discarded. The SSME is the only large liquid fuel motor that can be used over and over again. Sadly this reusability relies on extensive and costly technical support. Each engine (originally intended to fly ten times before major servicing) must be disassembled and rebuilt after every mission. This is so costly that it would probably be cheaper to discard the engine after every flight. Then there were the infamous tiles. Each Shuttle Orbiter is protected during re-entry to EarthтАЩs atmosphere (when its skin temperature can exceed 1250€ђ C) by typically 21 801 heat-resistant tiles and 1977 thermal blankets. Each tile is unique and identified by number. During the ShuttleтАЩs development process these displayed an embarrassing tendency to fall off the craftтАЩs airframe.
A vision of the future when manned spaceflight is routine painted in 1976. (Image credit: NASA)
Enterprise was used for many tests including a series of gliding flights. Originally when this testing was complete, Enterprise was to be made space-worthy and flown along side her sister ships. However so much was learned while Enterprise was being built, that the other later Orbiters were very different in detail. Upgrading Enterprise to the same standard was too difficult so Enterprise never flew into space. The project used a lot of new technology, and developing the TPS and Shuttle Main Engines took longer than expected. The first Shuttle flight was pencilled in for 1979 but this was delayed by nagging technical faults.
A new era in spaceflight dawns. The maiden flight of Space Shuttle Columbia on 12 April 1981. This was one of only two missions that had a painted external tank. (Image credit: NASA)
Columbia was successfully launched for the first time on 12 April 1981 from the Kennedy Space Center