NASA called off its attempt to launch the final voyage of the space shuttle Endeavour today (April 29) because of a malfunction in one of the spacecraft's critical power units.
"It's unfortunate for the [Endeavour] team and Mark Kelly and his crew, but today the orbiter's not ready to fly, and as we always say in this business, we will not fly before we're ready," launch director Mike Leinbach said.
Two heaters on one of Endeavour's auxiliary power units, which power hydraulics systems on the shuttle during its return to Earth, failed this morning, rendering the unit useless.
"The troubleshooting proved that it was a hard failure," Leinbach said. "We were not able to get it to come to life no matter what we did."
Mission managers decided to delay at least 72 hours to look into the source of the problem.
The next chance to launch Endeavour comes Monday (May 2) at 2:33 p.m. EDT (1733 GMT) from Launch Pad 39A here at Kennedy Space Center.