Despite a series of resent setbacks, including hurricanes and falling foam, the centerpiece of the US manned space program â€“ the Space Shuttle fleet â€“ is set to return to orbit as early as May 2006 (a window of May 3 to May 23 – target May 16), according to Shuttle program officials.
In a Friday press conference titled ‘Space Shuttle Program Status Briefing,’ â€œMay  looks very doableâ€, remarked William Gerstenmaier, associate administrator for Space Operations.
â€œI think weâ€™re beginning to have our hands well around the technical problems that we have and to find the fixes that are going to be necessary to fly again,” Wayne Hale, Shuttle Program Manager added. The most recent technical problem originated during the STS-114 mission in July, when a briefcase-size piece of foam fell off Discoveryâ€™s external tank during liftoff.
Richard Gilbrech, the NASA engineer heading up the â€œtiger teamâ€ charged to investigate the foam loss during STS-114, has identified what may turn out to be a structural issue with the Shuttleâ€™s external tank. The PAL (Protuberance Air Load) ramp was added to the tank to protect it from unstable air flow before the rampâ€™s aerodynamics were understood.
â€œIf we find that [the PAL ramp] is not required or perhaps a much smaller ramp is required,” noted Hale, â€œand we can eliminate some of the foam from outside the tank, then we have eliminated something that can cause problemsâ€. Hale added that the goal is to eliminate the need for the PAL ramp on future external tanks.
Regarding the external tank being built for STS-121, the Atlantis mission scheduled for May 2006, he continued “the PAL ramp will be dissected and looked at very carefully for what we can learn from thatâ€.
Responding to the suspicion that worker negligence was a factor in the foam problem on STS-114, Gilbrech insisted, â€œI want to make it clear that we found no negligence on the part of the workers.”
Post-Columbia procedures require more human handling of the foam, which may crush the fragile material. Gilbrechâ€™s team is evaluating new techniques for applying the foam to the structure, lessening the risk of mishandling it.
Gilbrech pointed out that handling the foam without damaging it is difficult, as it is largely filled with air. In rethinking the foam as a structure, those applying it must keep in mind that itâ€™s primary function is protect the tank from the stresses of ascent and the large temperature fluctuations experienced throughout the flight. The foam must remain stable and remain adaptable to the heat and humidity of the air at launch, and the extreme cold of the liquid fuel carried in the external tank.
STS-114 was the first mission which used a new foam known as BX265. Gilbrechâ€™s investigation discovered that an older type of spray used to fasten an older foam to the tank may have left “weak spots” between the pieces of the new foam. It was also confirmed that workers had entered the intertank flange area of the tank to carry out work.
Compounding the foam problem, is the devastation wreaked by hurricane Katrina on the gulf coast region.
Hale acknowledged hurricane Katrinaâ€™s impact on the External Tank operations at Michoud, saying that â€œthe infrastructure damage equals the loss of three months of workâ€, but added â€œour amazing workforce is coming back to work and they are making amazing progressâ€. Nearly one-fourth of Michoudâ€™s 2,000 workers have returned to work, and most are anticipated to rejoin their colleagues by December 1.
STS-1, the Shuttle programâ€™s first mission, was flown by
The Shuttle program was put on hold following the Challenger disaster in January 1986, when an O-ring on the right booster failed just 73 seconds after launch.
One memorable moment of the Shuttle program was STS-82, a ten day mission flown in February 1997 aboard Discovery to upgrade the Hubble Space Telescope.
If all goes as planned, the shuttle fleet will resume flights in May 2006, beginning with mission STS-121, the first of nineteen flights planned before retiring the orbiter at the end of 2010. Of those flights, eighteen will take the orbiter to the International Space Station, completing construction, while one will service the Hubble Space Telescope.