The space shuttle Endeavour launch will occur no earlier than May 8, NASA said Monday.
Technicians have identified the cause of a heater malfunction that prompted the space agency to scrub Friday's planned launch, but repair work will take several days.
Just prior to the Friday afernoon launch, NASA discovered that Endeavour's auxiliary power unit had failed. It was so late in the game that the mission's astronauts were already en route to the shuttle. NASA quickly shut things down, and upon further inspection, discovered a problem with a box of switches that controls power feeds, known as the aft load control assembly-2 (ALCA-2).
"That basically means the power is not getting out to the heaters that weren't working on launch day," Space Shuttle Program Launch Integration Manager Mike Moses said in a statement.
At this point, NASA plans to remove and replace the box, but that will take several days. Once it's installed, the team has to test it and make sure it's working properly, a process that will take at least two days. As a result, shuttle managers will meet in the next day or two to determine the next shuttle launch date, but it is not expected to be any earlier than May 8.
For now, launch pad workers have drained Endeavour's fuel tank, and the rotating service structure, which protects it from the elements and allows for external access to certain parts of the shuttle, was once again placed around Endeavour.
The mission's astronauts returned to NASA's Johnson Space Center on Sunday for several days of additional training.
The Endeavour launch is the second to last launch for NASA's space shuttle program. Atlantis is scheduled to travel to the International Space Station sometime in late June. Discovery returned from the ISS in March after several months of delay due to weather and cracks.
Among the items Endeavour will carry to the ISS is the Alpha Magnetic Spectrometer-2 (AMS). It will be used to measure cosmic rays to gain a better understanding of cosmic radiation; a challenge for long-duration spaceflight. It might also help uncover the mysteries involved in dark matter or missing antimatter, NASA said. The 15,000-pound AMS is expected to be operational for the rest of the station's life; at least 10 years.