Many people know the streamlined craft commonly called the Space Shuttle by sight. It is roughly the shape of an airplane, smaller than the 747 that transported it. It could land like a plane, too, coasting smoothly onto a runway.
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In reality, the spaceplane is the Orbiter Vehicle, just one part of the three-part Space Shuttle system. A series of six were built, including the experimental Enterprise. The five fully operational orbiters flew 135 missions in total, launching from Kennedy Space Center in Florida to deliver parts to the International Space Station, launch satellites, conduct science experiments, and launch the Hubble Space Telescope. Two other Space Shuttle components, the solid rocket boosters and external fuel tank, were jettisoned away from the orbiter vehicle before it reached orbit.
The first shuttle was named the Enterprise, after the spacecraft from Star Trek. NASA had originally wanted to call it the Constitution, but Star Trek fans launched a write-in campaign that won them over. (Note: That makes two Star Trek-inspired technologies in two Spacecraft of the Week stories.) Enterprise never went into space; instead, it was used for testing.
In 1972, Rockwell International received a $2.6 billion contract to build the first Space Shuttle orbiter. Rockwell’s aerospace and defense unit would be acquired by Boeing in 1996, around the time they were working on the fourth orbiter, Atlantis. Boeing already had some experience with the orbiters, since they had modified a commercial 747 into the first shuttle carrier aircraft.
Robert Thompson, NASA program manager for design and development through the first flight, talked this week with PDD about the development of the shuttles.
“What we wanted to do after Apollo was to build a general purpose work vehicle that you could load up with a pretty good payload, up to ten people, and fly into Earth’s orbit and do a considerable amount of work, and then you could pack everything up and come back down,” Thompson said.
“The Space Shuttle was the first time we had attempted to build a vehicle that could come back from orbital flight, maneuver through the atmosphere, and land on a runway,” he said.
NASA had attempted to perfect that technique during Project Gemini, NASA’s second human spaceflight program, which took place from 1961 to 1966. However, it didn’t take shape at the time.
On Gemini, NASA had tried to bring the craft back into Earth’s atmosphere using a ballistic shape slowed down by a parachute. Opening the parachute proved difficult, and the vehicle was not very maneuverable. Gemini landed in the ocean, and engineers went back to the drawing board to try to make the shuttle orbiter land like an airplane.
“The key to getting the shuttle to work was to develop a thermal protection system that would allow us to enter the earth’s atmosphere at a very high velocity without overheating,” Thompson said.
The thermal system was “basically made out of glass,” Thompson said. The reinforced carbon-carbon sheathing used on the hottest spots, including the nose cap and the leading edges of the wings, could handle re-entry temperatures exceeding 2,300 degrees Celsius, reflecting the heat back away from the vehicle. “The combination of the carbon material and the glass material glued to the outside of the shuttle kept it from getting too hot,” Thompson said.
The body of the orbiter was made of aluminum, which melts at about 660 degrees Celsius.
Its landing was “very different” from Gemini’s, Thompson said. The Space Shuttle orbiter didn’t land faster than its predecessor, but was much more maneuverable.
The orbiter’s three main engines were liquid-fueled and arranged in a triangular formation aft. Orbital maneuvers and attitude control was initiated through the Reaction Control system, rocket thrusters mounted fore and aft and controlled by a computerized flight system.
There were no big structural difference between the different shuttles in the fleet, Thompson said. The basic air frame remained the same. “The only thing that changed is some of the avionics were changed to more advanced avionics, and occasionally some small items would be replaced by better material or better items. But the vehicle basically did not change during its 30-year lifetime.”
Atlantis was the first of the shuttles to fly with a glass cockpit, or Multifunction Electronic Display System. It received this upgrade during its second major overhaul.
Tragically, the Space Shuttle orbiters are also known for the loss of two of their number. Challenger and Columbia both flew many missions before they were destroyed, Columbia in re-entry after a piece of thermal foam from the external fuel tank damaged the left wing, and Challenger during launch.
The Atlantis flew its final mission in July of 2011, delivering parts to the International Space Station as well as testing science systems. The Space Shuttle system was gradually retired, due to lack of funding and changing policies. Atlantis, the youngest orbiter from the Space Shuttle program, now resides at the Kennedy Space Center in Florida.
For now, American spaceflight is in the hands of commercial enterprise. In the interview, Thompson said that engineering lessons learned during the building of the Space Shuttle orbiter are applicable to smaller projects, too. “Developing a very risky high speed airplane is very different from developing commercial products, but some of the same procedures have to be followed, some of the same care has to be taken in the design, even if it’s just a washing machine.”
Spacecraft of the Week is a feature showing the engineering and design that went into creating the vehicles that explore our universe. Illustration by Larry Corby.
Filed Under: Aerospace + defense