by Jim Slade.
Launch to space.
Photo, courtesy National Aeronautics and Space Administration.
The space shuttle was authorized by President Richard M. Nixon as the Apollo-Soyuz and Skylab projects were completed. It was to be America's chief launch vehicle for the indefinite future, capable of lifting heavy payloads for both civilian and military interests. In that respect, it was something of a "horse designed by a committee," since all interested parties got their say in the spaceship's features.-0-
President Nixon and his advisors were pleased that the machine would be reusable, hopefully ending the use of so-called "throwaway rockets." They were told that the system would eventually be capable of as many as 60 flights per year, a promise that turned out to be physically impossible due to the complicated machine's need for extensive grooming between each mission. The best the shuttles have ever managed is about 8 flights a year among them.
As it was first envisioned, the shuttle would be designed and built in tandem with a space station. The plan was to have the orbiters ready to carry the station parts into orbit. Budgetary considerations led Nixon to decide in favor of building the shuttle first and picking up the station at some later date. That left the shuttle without a primary mission, so it was "farmed out" to whomever had something to launch.
If you look at the machine, you see that it has a 15 foot wide by 60 foot long cargo bay. That's the military's signature, since they wanted it to have enough room for their largest spy satellites (think of the Hubble space telescope as a comparison). After the Challenger disaster, the military lost interest in the shuttles for a number of reasons, including their inability to control its operation, and they went back to launching on the good old "throwaways," leaving the shuttles and manned flight to NASA, some commercial interests and science until a future president would give the go-ahead for a station. Ronald Reagan was that "future President." But now, without Columbia available for the science missions, almost all the remaining three shuttle's (Discovery, Endeavour and Atlantis) time will be devoted to servicing the station. More about that later.
Columbia was the first orbiter off the Rockwell International production line, destined to be the primary "test article." It first flew in April of 1981 with a crew of two: John Young and Robert Crippen. There were three more test flights before the system was considered "operational." After the fourth trip, Rockwell began publishing advertisements saying: "When a spaceship lands on earth, it comes from Rockwell," emphasizing the fact that here was a spaceship that could land as an airplane so it could live to fly another day. As such, it easily qualified as the most complicated machine in the world. It still does.
Above right, one of the shuttles landing at Edwards Air Force Base, California. NASA photo.
The system is amazingly powerful and capable. When you watch it launch, you're seeing 4 and a half million pounds of machinery leaving the ground under control on a collective rocket thrust of about 7- to - 7.5 million pounds. Its design is a mind-boggling geometry that makes it a launch vehicle, orbiting space station and airplane/glider in one package. It is extremely capable, but it still has definite limitations based on the state of current technology, physical law and budgets.
Here are the answers to some questions frequently asked since the Columbia accident:
Q: Is there a simple way to say what happened?
A: No, but I will try. The best and most logical scenario is that the 2000 degree plasma (superheated gasses) that built up as the shuttle's wings met the atmosphere got inside the left wing or wheelwell through some sort of hole. In this scenario, it took only minutes for the wing to melt internally. That would account for the sequential die-off of sensors in the wing that measured hydraulic temperatures, temperatures on the actuators that move the wing's maneuvering surfaces, and so on. When the ship got deeper into the atmosphere, it appeared to be pulling or "yawing" to the left. Moments later, it broke up.
None of that, of course, explains what made the hole. That, and what can be done to prevent it in the future, will be the question that everyone pursues. The answer could even have political effects for the space agency.
Q: What is the current state of the investigation?
A: An investigating board has been organized outside of NASA. Headed by Admiral
Harold Gehman, who investigated the attack on the USS Cole, the board will be the official source of information, although it is clear that NASA engineers are pursuing answers themselves. The engineers will furnish material and support to the board. There is concern that the board may not independent of NASA, and steps are being taken to correct that.
Q: Could Columbia have been aborted to a safe landing during powered flight to orbit?
A: Yes. The spaceship can be separated from its fuel tank after the booster rockets burn out. With the speed imparted to the point where the decision is made to abort, it can be directed back to the Kennedy Space Center or it can be sent for a gliding landing in Africa or Spain. If the problem is discovered late in the climb to orbit (for instance, loss of one or more engines) it can be aborted to orbit. However, no one knew during launch that there may have been a problem with the shuttle's left wing, and the shuttle flew to what was considered a normal orbital insertion.
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