NASA on Monday said it has resolved a power issue on the space shuttle Endeavour and set its launch date at May 16. As a result, the launch for the shuttle Atlantis has been pushed to early July.
"Right now we're in good shape," Mike Leinbach, shuttle launch director, said during a Monday press briefing. "Endeavour's looking good [and the] team is upbeat."
If things stay on track, Endeavour will take off at 8:56am Monday. NASA tentatively selected May 16 for a launch date last week, but made it official today.
Endeavour was scheduled to depart for the International Space Station on Friday, April 29, but just prior to the scheduled 3:47pm 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 a load control assembly-2 (LCA-2).
NASA removed the malfunctioning box (click right for larger image) last week and replaced it with a new one. As you can see, the box—which NASA said is about the size of a large shoebox—has multiple wires and electrical connections. It would, therefore, be too time-consuming to figure out exactly what went wrong inside the box and still launch in the next few days, so a replacement was installed.
Replacing the heaters, meanwhile, would be a "very invasive process," said Space Shuttle Program Launch Integration manager Mike Moses.
As a result, technicians installed new wiring that bypasses the suspect electrical wiring connecting the switchbox to the heaters. They are now completing tests of other systems powered by that switchbox.
Moses did suggest one theory about what went wrong. Shuttle thermostats have a mechanism whereby they shut down if they overheat. When they were testing those thermostats at one point, technicians noticed that there was a spike in current right before they shut down. If it's a short in the wiring, Moses said, that would indicate that the problem was isolated to a heater or the thermostat. Since NASA has since replaced the box and the wiring, everything "should be in good shape," he said.
Endeavour Commander Mark Kelly and his crew will travel from Houston to Kennedy Space Center on Thursday, and are expected to arrive around 11am Eastern.
On the Atlantis front, NASA has now pushed that from late June to early July. Atlantis will be the final launch for NASA's space shuttle program, at which point the fleet will retire and space travel will shift to commercial spaceflight endeavors.
NASA won't set an exact date for the Atlantis launch until Endeavour has launched, Moses said. They will have to make some repairs to the launch pad before Atlantis can be rolled out, and won't know the extent of the damage until they get out there. But for those hoping for a very patriotic end to the space shuttle program, Moses said they Atlantis launch will likely be after July 4.
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.