NASA Sets May 16 for Last Launch of Endeavour; Atlantis Slips to July

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KENNEDY SPACE CENTER – NASA managers set May 16 as the new launch date for the final flight of Space Shuttle Endeavour after technicians completed work to rewire and retest a switchbox in the orbiters aft compartment. Shuttle managers ordered the repair work following a heater malfunction that forced NASA officials to call off the planned April 29 launch.

At a briefing for reporters today (May 9) at NASA’s Kennedy Space Center in Florida, Shuttle managers Mike Moses and Mike Leinbach announced that Endeavour’s last liftoff is now targeted for 8:56 a.m. EDT on Monday, May 16.

“Right now, we’re in good shape,” said Shuttle Launch Director Mike Leinbach.

“Endeavour’s looking good, the team is upbeat. I went to the meeting this morning and they’re ready to go. Hopefully, this time the heaters will work and we’ll be able to launch on time next Monday morning.”

The STS-134 mission is the penultimate flight of the space shuttle program and will deliver the $2 Billion Alpha Magnetic Spectrometer to the International Space Station.

Endeavour’s last launch attempt on April 29 was scrubbed about four hours prior to blastoff when critical hydrazine fuel line heaters failed to turn on inside one of the orbiters three auxiliary power units (APU’s).

Technicians have been working around the clock to resolve the problems and determined that the likely cause of the heater failure was an electrical short inside the ALCA -2 load control assembly box located in the aft section of the shuttle (see photo).

They installed about 20 feet of new wiring, a new ALCA box and then retested all related systems over the past week and a half.

“We’ve replaced everything except the heaters, and we’ve wrung those out with at least five separate checks and full functionals afterwards and now have extremely high confidence that the problem is no longer on the ship or in any of the electronics,” said Mike Moses, the Shuttle launch integration manager at the Kennedy Space Center.

The APU’s control the shuttles hydraulics which power the steering of the main engines, wings, wheels and rudders during ascent and re-entry. The three units must all be fully functional before NASA can commit to any shuttle launch as part of the launch commit criteria (LCC). If the heaters fail during flight, the hydrazine can freeze and clog the fuel lines and render the hydraulics inoperative. A rupture in the lines could result in toxic hydrazine leaking into the shuttles aft engine compartment.

The potential launch window for Endeavour’s final flight extends through May 26, except for May 21.

The all veteran six man crew led by Shuttle Commander Mark Kelly is due to fly to the Cape on Thursday, May 12 from their training base in Houston. The STS-134 mission has been officially extended to 16 days from 14 days and will include 4 spacewalks.

The launch countdown will commence on Friday, May 13 from the beginning of the nominal 41 hour countdown sequence.

As a consequence of Endeavour’s delays, the launch of the very final shuttle mission of Space Shuttle Atlantis will likely be delayed to mid-July, although Moses and Leinbach did not give a specific target date.

Read my related stories about the STS-134 mission here:
Endeavour’s Final Launch further delayed another Week or more
On the Cusp of Endeavour’s Final Flight
Brush Fires Erupt at Kennedy Space Center during Endeavour’s Last Countdown
Commander Mark Kelly and STS-134 Crew Arrive at Kennedy for Endeavour’s Final Flight
President Obama to Attend Endeavour’s Last Launch on April 29
Shuttle Endeavour Photo Special: On Top of Pad 39A for Final Flight
Endeavour Mated to Rockets for Last Flight Photo Album
Endeavour Rolls to Vehicle Assembly Building for Final Flight

NPR Radio interview including Ken here:
Shuttle Fixes Will Take At Least One Week