The launch of U.S. space shuttle Endeavour on its final voyage will be no earlier than May 8, after technical problems uncovered last week proved more complex than originally thought, the U.S. National Aeronautics and Space Administration (NASA) announced Sunday.
NASA tried to launch Endeavour on Friday on its 25th and final flight to deliver the 2-billion-dollar Alpha Magnetic Spectrometer (AMS) particle detector to the International Space Station. AMS, a particle physics detector, is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments are designed to help researchers study the formation of the universe and search for evidence of dark matter, strange matter and antimatter, Xinhua reported.
However, the launch was called off after engineers detected a failure in one of two heater circuits associated with Auxiliary Power Unit (APU) 1. Heaters are required to keep the APUs' hydrazine from freezing on orbit.
NASA hoped Endeavour would lift off on Monday. But further trouble-shooting indicated the glitch was more complicated than officials hoped initially.
The failure appears to be a power problem within the aft load control assembly-2, a box of switches controlling power feeds.
"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.
NASA's plan is to remove and replace the box, but that work and related testing will take several days to complete. Once the new box is installed, the team must verify it's working properly -- at least a two-day process -- and perform forensics on the failed box.
"We can tell you, pretty much, that it's not going to be any earlier than (May 8)," Moses said. "We're really not even setting the schedules today. There's still a whole lot of short-term work that has to be done."
Endeavour's six astronauts have returned to NASA's Johnson Space Center in Houston for a few days of additional training before they report to Kennedy for the next launch attempt.
"Responding to problems is one of the things we do best around here, and the team always likes a good challenge," said Shuttle Launch Director Mike Leinbach. "I'm sure we're going to be really glad when Endeavour's finally on orbit, but right now, the team is upbeat and ready to execute."
Endeavor, which has been promised to the California Science Center in Los Angeles upon its return, was the replacement ship for Challenger, which was lost in a 1986 explosion as it ascended over the Atlantic that killed seven astronauts.
It will be the second of NASA's three surviving shuttles to be retired. Sister ship Discovery, which will be transferred to the Smithsonian National Air and Space Museum, completed its last flight in March. Atlantis' final launch is scheduled for June 28.
When the U.S. space shuttle program officially ends later this year, the Russian space program's Soyuz capsule will be the only method for transporting astronauts to and from the station.