A FAULTY HEATER part on the Endeavour shuttle due to launch from Florida last night forced NASA to postpone the event until at least Monday with preparations already far advanced.

The president was on his way. Space shuttle Endeavour’s astronauts were riding out to the launch pad in a van. And a wounded Rep. Gabrielle Giffords had flown in from her Houston rehab hospital to watch her husband blast off Friday on the historic, next-to-last shuttle mission.

Then it all came to a sudden stop.

Without warning, a faulty heater part forced NASA to scrub the launch and slam the brakes on the space agency’s biggest event in years, a flight made more fascinating to many by the plight of Giffords and her husband, Mark Kelly, the mission commander.

Giffords’ staff tweeted their disappointment:

Bummed about the scrub!! But important to make sure everything on shuttle is working properly

Travel plans for the Arizona congresswoman, who is still recovering from a gunshot wound to the head from an assassination attempt in January, are still up in the air, said her spokesman, C.J. Karamargin.

He said she is waiting until Sunday when NASA should know more about a possible launch date.

President Barack Obama and his family came to Cape Canaveral anyway, and he and his family met with Giffords for about 10 minutes. Karamargin said only that Giffords was pleased to meet with them.

The congresswoman’s husband greeted Obama in a corridor, saying: “I bet you were hoping to see a rocket launch today.”

Obama replied: “We were hoping to see you.” The two men shook hands and embraced.

The president told Endeavour’s six astronauts he is still hoping to get back to Florida for a shuttle launch.

As many as 700,000 tailgaters and other spectators had been expected to pour into the seaside area for the liftoff, one of the biggest launch-day crowds in decades. It would have been the first time in NASA history that a president and his family witnessed a launch.

Giffords arrived on Wednesday, nearly four months after the shooting in her hometown of Tuscon, but the 40-year-old congresswoman hasn’t been seen in public. She has difficulty walking and talking and wears a helmet because doctors removed a large piece of skull to allow for swelling of her brain.

She had planned to watch the launch from a private VIP viewing area along with the other astronauts’ families before the countdown was halted about 3½ hours short of the 3:47 pm liftoff. NASA’s silver-colored astrovan did a U-turn and brought the astronauts back to their crew quarters.

Giffords’ Houston doctors declined to say whether a prolonged stay away from her rehab center would cause problems. It was unclear whether she is continuing her therapy while in Florida; her staff would provide no details.

Engineers aren’t certain what part on the heating system — needed for launch and landing — needs to be replaced. To fix the heater, technicians will have to crawl into the engine compartment.

If it is a simple fix, NASA could make another launch attempt as early as Monday, Tuesday or Wednesday, but if not, the flight could be delayed to May 8 or later, said launch director Mike Leinbach.

After Endeavour, there is only one more shuttle flight — by Atlantis — before NASA ends the 30-year-old program and the orbiters become museum pieces.

When Endeavour finally flies, it will be the last mission in its 19-year history. It will deliver a $2 billion instrument that will search the universe for antimatter and dark energy.

At the space center, astronaut Clayton Anderson was typically stoic.

“Of course, it’s always disappointing, especially for the crew,” he said. “NASA has a great safety record and they’re going to do it the right way.”

- AP