NASA grounds Endeavour until Monday

CAPE CANAVERAL, Fla., April 29 (UPI) -- NASA scrubbed Friday's scheduled launch of space shuttle Endeavour in Florida because of a problem with two heaters.

President Obama and U.S. Rep. Gabrielle Giffords, the wife of shuttle flight commander Capt. Mark Kelly, had planned to attend the 3:47 p.m. EDT launch from Cape Canaveral for a 14-day mission to the International Space Station.

Giffords' staff tweeted the congresswoman was "bummed about the scrub!! But important to make sure everything on shuttle is working properly."

NASA said it would not attempt a launch before Monday afternoon.

"During today's countdown, engineers detected a failure in one of two heater circuits associated with Auxiliary Power Unit 1," NASA said on its Web site. "Heaters are required to keep the APUs' hydrazine from freezing [in] orbit. Attempts to activate the heater were not successful and engineers now believe the problem might be associated with a Load Control Assembly, which is a switchbox, located in the aft end of Endeavour, or an electrical short in the wires leading into or out of the switchbox."

Obama met with Giffords for 10 minutes before meeting with the full crew of Endeavour.

"I bet you were hoping to see a rocket launch today," Kelly told Obama, a White House official said.

"We were hoping to see you," Obama replied.

The last sitting president to attend a shuttle launch was Bill Clinton, who watched astronaut and U.S. Sen. John Glenn, D-Ohio, lift off in Discovery Oct. 29, 1998 -- at age 78 the oldest person to fly in space and the only one to fly in both the Mercury and shuttle programs.

Project Mercury was the first U.S. human spaceflight program, from 1959 to 1963. Glenn was the first American to orbit Earth Feb. 20, 1962.

Jeffrey G. Spaulding, shuttle test director at the Kennedy Space Center, said NASA had at least three opportunities for liftoff next week.