The likely reason for Friday's failure of shuttle Endeavour's heater circuit associated with the auxiliary power unit 1 (APU-1) has been identified, NASA reported.
On Friday, the final launch of Endeavour was rescheduled for Monday, but it has been delayed again as NASA technicians have failed to fix technical problems with the heaters, which are required to keep the APUs' hydrazine from freezing in orbit.
"The failure appears to be a power problem within the aft load control assembly-2 (ALCA-2), a box of switches controlling power feeds," the U.S. space agency said on its website.
"That basically means the power is not getting out to the heaters that weren't working on launch day," said Space Shuttle Program Launch Integration Manager Mike Moses.
Moses said the launch is not expected before May 8.
Endeavour is to deliver a $2 billion particle detector to be mounted outside the International Space Station (ISS).
This will be Endeavour's final flight and the next-to-last shuttle mission. The U.S. space agency, which says its shuttles are outdated and too expensive to maintain, will begin sending astronauts to the ISS on board Russia's Soyuz rockets.
MOSCOW, May 2 (RIA Novosti)