NASA has decided to go ahead with Monday’s launch of the space shuttle Endeavour — weather permitting — after a last check of shuttle motors, Shuttle Program Manager Ron Dittemore said Sunday.
For two days, the launch date seemed uncertain, after the unexpected discovery of a defective joint in the motor of another shuttle.
“We have reviewed the data and concluded that the engine is safe to fly,” Dittemore said at a news conference.
With that announcement, the countdown continued for a launch set for 12:47 p.m. (1747 GMT) Monday at the Kennedy Space Center here.
Only the weather, with just a 40 percent chance of favorable conditions, could compromise that schedule, in which case NASA will set the launch back to Tuesday.
It will be the 97th flight of a US space shuttle since the start of the program in 1981.
Routine inspections after December’s flight of the space shuttle Discovery revealed that a circular metal joint on the interior of an engine fuel pump had come loose during launch and been damaged by turbine blades.
Had the pump or the motor failed, the Discovery team would have had to abort the launch and make a risky emergency landing at one of several bases worldwide designated for that purpose.
NASA said a subcontractor, which it did not name, was responsible for the defect — “a clear mistake intolerable to us.”
The subcontractor’s production records showed that the joint had been rejected during post-production quality control procedures, but for unknown reasons was installed on the interior of the pump anyway.
Before giving a green light for Monday’s launch, flight officials wanted to make sure there was no sign of a similar problem aboard Endeavour, which is set to carry six astronauts — four Americans, a Japanese and a German — on an 11-day mission to gather data for a three-dimensional map of the Earth’s surface.
NASA evaluated the risk level for Endeavour and found it acceptable.
“What we’ve learned was that the likelihood of having a failed tip seal to reoccur again is very, very low,” Dittemore said.
Asked why NASA is proceeding with the launch despite the problem, Dittemore said: “We are not launching with a problem, we are launching with a potential problem that we have cleared.”
The circular joint — there are a total of 18 in shuttle motors — is situated on the interior of one of three pumps which inject high-pressure liquid hydrogen into the motors.
It serves to limit the pressurized air flow around the tips of the turbine blades, and according to its manufacturer, was designed to accommodate the rubbing of the blades, which turn at 37,000 rotations per minute.
On January 28, 1986, defective watertight joints on one of two rocket boosters on the space shuttle Challenger caused it to explode shortly after lift off, killing all seven people on board.
The tragedy led NASA to review its shuttle designs entirely, and caused a 32-month suspension of its manned space flight program.
The plan for near-term Shuttle and International Space Station launches now includes:
Date Mission/Vehicle Payload Jan 1 STS-99/Endeavour Space Radar Topography Mission Apr13 STS-101/Atlantis ISS maintenance/Assembly Flt 2A.2a TBD ISS-1R/Proton Zvezda service module/Assembly Flt 1R TBD STS-106/TBD ISS Zvezda outfitting/Assembly Flt 2A.2b
Whether or not STS-106 will be required and any necessary adjustments to the target launch dates for subsequent Shuttle flights will be dependent on the launch date scheduled for Zvezda.
A launch date for Zvezda is expected to be selected following an International Space Station Joint Program Review to be held next month. The composition of crews for a revised STS-101 and STS-106 is under review.
T-TIME LENGTH OF HOLD HOLD BEGINS HOLD ENDS T-27 hours 4 hours 9:30 am Sat 1:30 pm Sat T-19 hours 4 hours 9:30 pm Sat 1:30 am Sun T-11 hours 12 hours, 57m 9:30 am Sun 10:27 pm Sun T-6 hours 1 hour 3:27 am Mon 4:27 am Mon T-3 hours 2 hours 7:27 am Mon 9:27 am Mon T-20 minutes 10 minutes 12:07 pm Mon 12:17 pm Mon T-9 minutes 10 minutes 12:28 pm Mon 12:38 pm Mon
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