Kennedy Space Center, Florida (CNN) -- The Arizona congresswoman who was shot in the head just four months ago sat comfortably Monday morning, watching and cheering as the space shuttle Endeavour, with her husband aboard, took off on its final voyage.

Mark Kelly commands the shuttle's 16-day mission to the International Space Station. His wife, U.S. Rep. Gabrielle Giffords, watched as Endeavour launched from the Kennedy Space Center just a few months after an assassination attempt at a public event in Tucson, Arizona.

"It was a great day," said Pia Carusone, Giffords' chief of staff, who spoke at a news conference after the launch. "We've been looking forward to this for several weeks."

When asked how Giffords reacted to the liftoff, Carusone said there were more cheers and clapping than words, but Giffords declared a resounding, "good stuff, good stuff!"

The mood was "very celebratory" as Giffords sat with her mother and other spouses to watch Endeavour's launch, Carusone said. The congresswoman's chief of staff did admit there was some concern earlier Monday about whether the launch would be scrubbed because of overcast skies, but she said that once the sun came out, the apprehension quickly lifted.

Two nurses working 12-hour shifts accompanied Giffords to the space center, Carusone said. The congresswoman was expected to return to the TIRR Memorial Hermann center in Houston to continue her rehabilitation Monday afternoon.

Carusone said she is not sure if Giffords would return to Florida for Endeavour's landing. The decision will be "up to her and her doctors," she said.

Giffords' recovery, which doctors have called remarkable, has garnered a strong outpouring of support from many people in the United States and around the world.

"The presence of Congresswoman Gabrielle Giffords at the launch inspired us all, just as America's space program has done for the past 50 years," NASA Administrator Charles Bolden wrote in a blog post shortly after Endeavour's liftoff.

Photos of the shuttle and NASA's launch countdown clock were posted on her Facebook page Monday morning.

Giffords, along with President Barack Obama, was in Florida on April 29, when Endeavour was originally slated to launch. That liftoff was scrubbed because of a problem with a heater aboard the shuttle.

But on Saturday, NASA officials said the heater problem had been fixed and the shuttle was "good to go" for its scheduled Monday takeoff.

"The system looks good, the weather looks good, and we should be in good shape for launch," Mike Moses, launch integration manager for NASA's space shuttle program, told reporters.

Several astronauts on the shuttle's six-person crew posted updates on Twitter as Monday's liftoff neared.

"Launch day. We should be pulling off Earth in a couple hours," Kelly posted just before 7 a.m.

Pilot Gregory H. Johnson described his breakfast: "2 eggs, 2 slices of bacon, fruit cup and an English muffin. Coffee was bold blend from Rwanda - black."

Mission specialist Col. Mike Fincke posted a picture of himself before and after putting on his space suit.

"Dear God, please bless our crew. Help us in our mission and to return safely home," he wrote in an earlier post, adding, "please help me not to mess anything up."

Endeavour is expected to dock at the International Space Station on Wednesday morning.

The items the shuttle is delivering to the station include spare parts, a high-pressure gas tank and the Alpha Magnetic Spectrometer-2, which NASA describes as a "state-of-the-art particle physics detector."

The detector is part of "a new experiment designed to reveal the origin and structure of the universe," NASA said.

Endeavour is scheduled to return to Earth on June 1. That is the same day the space shuttle Atlantis is slated to roll out to the launch pad in anticipation of the final mission in the space shuttle program's 30-year history.

The shuttle program's end -- and the uncertainly surrounding the future of NASA and the U.S. space program -- has been a hot topic in recent months. Michael D. Leinbach, NASA's shuttle launch director, acknowledged Saturday that "the mood is a little bit downcast" in the space agency, especially as some NASA employees recently received notices warning that they could lose their jobs.

"The timing is a little unfortunate, but we've all known it's been coming," he said.

Endeavour entered service in 1992 as a replacement for the ill-fated space shuttle Challenger. Leinbach, who was a test director for that inaugural mission, said the orbiter remains in prime condition 19 years later.

"She still looks awfully good out there," Leinbach said. "She's got a lot of life left in her, but that's not meant to be."

CNN's Rich Phillips contributed to this report.