NASA’s space shuttle Endeavour punched through a veil of clouds this morning, making its 25th and final ascent into space after technicians quickly repaired damage to its heat shield.

“This is a both a sad and proud moment for your launch team and America,” a Mission Control team member at Kennedy Space Center in Florida told the crew of seven shortly before launch at 8:56am EDT.

Commanding the orbiter’s final mission, called STS-134, is astronaut Mark Kelley — husband of U.S. representative Gabrielle Giffords (D-Arizona), who is still recovering from a failed Jan. 8, 2011 assassination attempt. The couple exchanged wedding rings prior to launch, and will swap back when he returns.

Thick clouds threatened to delay the launch, but they thinned out enough to satisfy mission controllers. Shortly after Endeavour’s astronauts boarded, ground crews spotted damage to the heat shield near the hatch. They quickly dispatched a team to fix the damaged tile.

Auxiliary power unit failures thwarted previous launch attempts in late April, but NASA reported all three were functioning normally after Endeavour separated from it’s freshly emptied 500,000-gallon fuel tank. The units provide hydraulic pressure for launch, re-entry and landing systems.

Endeavour carries the Alpha Magnetic Spectrometer in its payload bay. Once at the International Space Station (ISS), astronauts will move the 15,000-pound particle physics experiment to the top of the ISS where it will search for evidence of dark matter, strangelets and antimatter. The device will also log cosmic ray exposure that astronauts may experience on prolonged trips to Mars.

Endeavour was first launched 19 years ago this May. In early July, space shuttle Atlantis is scheduled to make its final flight, closing out NASA’s space shuttle program.

Photo: The space shuttle Endeavour lifts off from Kennedy Space Center in Cape Canaveral, Fla., Monday, May 16, 2011, beginning a 14-day mission to the international space station. (AP Photo/Chris O’Meara)

See Also: