NASA scrubs final space shuttle Endeavour launch

At least 72 hour delay

NASA has postponed the final launch of space shuttle Endeavour by about 72 hours or more. The launch had been set for 3:47pm Eastern time on Friday, but it has now been delayed until at least 2:33pm on Monday.

Shuttle launch director Mike Leinbach scrubbed the launch as Endeavour engineers investigate the failure with one of the two heater circuits associated with an Auxiliary Power Unit (APU). The heaters prevent the APU's hydrazine from freezing while the shuttle is in orbit.

According to the NASA website, the Endeavour team was unable to activate the heater, and engineers believe the problem could be associated with the Load Control Assembly (a switchbox at the aft end of the spacecraft) or an electrical short in the wires that connect to the Load Control Assembly.

NASA will drain Endeavour’s external tank, and by tomorrow afternoon, technicians will enter the shuttle's aft compartment to access the avionics bay that holds the Load Control Assembly. They may need to remove and replace the switchbox or fix a short in the electrical wiring.

NASA has scheduled a news conference for 4pm eastern to discuss the launch scrub. ®