Bolt hole mystery could delay next shuttle launch
Posted: September 30, 2001

An Orbital Maneuvering System (OMS) engine firing causes this bright glow at the aft end of the shuttle. Photo: NASA
NASA officials will decide this week whether shuttle Endeavour's orbital maneuvering engine pods must be removed for inspections, a move that would likely delay the ship's November space station mission until next year.

Engineers uncovered elongated bolt holes on connection joints that hold the engine pods onto sistership Columbia, prompting officials to consider the time-consuming job of checking Endeavour and other shuttles for similar defects.

Engineers are expressing concerns over the issue because -- given a variety of circumstances -- the attach fittings with elongated bolt holes can fail during flight. The risk of failure is even greater during some situations such as some emergency abort scenarios.

Endeavour is scheduled to liftoff at 7:35 p.m. EST November 29 carrying the fourth crew to live and work aboard the international space station, replacing the three-man team currently residing on Alpha.

But if engineers choose to go ahead and with inspections and possibly repairs on Endeavour, the launch would probably be postponed until the first two weeks of January.

NASA managers plan to meet again this week to determine if Endeavour is safe to launch "as is" on November 29, or if they will order engineers in Florida to remove one or both of the pods for inspections.

Similar checks could also be conducted on shuttles Atlantis and Discovery. Atlantis is preparing for launch to the international space station next February and Discovery is supposed to be taken out of flight rotation for an extensive modification and inspection period over the coming months.

The space shuttle's orbital maneuvering system engine pods are used for major orbit-changing firings and to slow the shuttle before the re-entry during the deorbit burn. The twin pods mounted to the aft end of the orbiter contain fuel tanks, maneuvering thrusters, and one large engine each. The units are attached to the shuttle using 12 connection joints, with each of those including the 14 suspect bolt holes.