CAPE CANAVERAL, Fla. -- Five astronauts can expect the safest ride to orbit in the history of piloted spaceflight this week, thanks to an improved main engine that will be tested in flight for the first time when shuttle Atlantis lifts off from the Kennedy Space Center.
Equipped with a new high-pressure fuel turbopump, the so-called Block 2 engine is the final result of a 15-year-long, $1 billion effort to make the shuttle's liquid-propellant rockets more powerful, safer to fly and less costly to maintain.
| Countdown Update |
| Atlantis remains on schedule for launch Thursday at 5:04 a.m. EDT (0904 GMT) but weather continues to be a major concern. For the latest on the countdown, and to learn more about the STS-104 mission, see our new Mission Page for the very latest. |
"The performance of this machinery is the best you'll get anywhere in the world," said Don McMonagle, a former NASA astronaut who is now a senior manager with Pratt & Whitney of West Palm Beach, Fla., the company responsible for building the turbopumps that serve as the heart of the redesigned engines.
The shuttle main engine is fed by a series of pumps that move liquid hydrogen (the fuel) and liquid oxygen (the oxidizer) through the engine's plumbing at the proper flow rate and pressure. The most critical parts of each engine are the high-pressure turbopumps, one each for handling the hydrogen and the oxygen.A failure of the high-pressure turbopumps during launch could, at minimum, result in an engine shut down that would force the shuttle crew to make an emergency landing or bail out over the ocean. At worst, a failing pump could lead to a catastrophic explosion in which there would be no hope for survival.
Complicating matters: in order to save as much weight as possible for the overall space shuttle, the main engines were designed during the early 1970s to milk the most energy out of the smallest and lightest package possible, resulting in powerplants that operated at the very edge of self-destructing every time they were flown.
"We had to design the engine where every ounce was important to us," said George Hopson, manager of the Space Shuttle Main Engine Projects Office at NASA's Marshall Space Flight Center in Huntsville, Ala.
NASA wound up with the most powerful rocket engine for its size in history. Together, the three shuttle engines generate more than a million pounds of thrust -- the energy equivalent of 23 Hoover Dams. And just one of the high pressure fuel turbopumps, barely larger than a typical automobile engine, has the power to send a column of liquid hydrogen 36 miles into the air.
The result also was an engine that experienced many technical problems, required major components such as the turbopumps to be removed and inspected between every shuttle mission, and demanded an overhaul so frequently that there were occasions in shuttle program history when the launch schedule greatly depended on when turbopumps would be available.
As the years progressed and weight savings were realized in the rest of the shuttle vehicle, NASA engineers decided it was worth adding weight back into the main engines -- some 240 pounds for the new fuel turbopump alone -- to make them safer and more reliable, Hopson said.
So, beginning in 1986, Pratt & Whitney was awarded a contract by NASA to take the original turbopumps and redesign them. At the same time, the main engine manufacturer -- Rocketdyne, now a part of Boeing -- worked with NASA to redesign other elements of the engine plumbing.
Next page: New pumps for NASA
advertisement
