The space shuttle Endeavour, bolted to the top of a jumbo jet, was to take off on Friday from Edwards Air Force Base for a last airborne victory lap over California en route to its final frontier and retirement home - a science museum in Los Angeles.

Riding piggyback on a specially modified Boeing 747, the 75-ton winged spaceship was scheduled to depart at 8:15 a.m. Pacific time (1515 GMT) on the final leg of its cross-country trip that started on Wednesday in Cape Canaveral, Florida. The scheduled departure was about an hour later than originally planned due to fog over the San Francisco Bay area.

After making at least 20 planned low-altitude passes over some of California's best-known landmarks and scientific institutions, including Disneyland and the Jet Propulsion Laboratory, Endeavour and its carrier jet are expected to land at Los Angeles International Airport at about 12:45 p.m. local time (1945 GMT).

Friday's flight from Edwards, about 100 miles north of Los Angeles in the Mojave Desert, will mark Endeavour's last ferry flight, and the final airborne journey for any of NASA's three surviving shuttles.

NASA retired Endeavour and the rest of its shuttle fleet last year after completing the U.S. portion of the $100 billion International Space Station, a permanently staffed research complex orbiting 250 miles above Earth.

Its arrival Thursday afternoon at Edwards was a homecoming of sorts for the California-made spacecraft, which was built as a replacement for Challenger, the shuttle lost in a 1986 launch accident that killed seven astronauts.

Endeavour went on to fly 25 missions, including 12 to help construct and outfit the space station, and logged nearly 123 million miles (198 million km) in flight during 4,671 orbits.

Seven of those missions ended with Endeavour landing at Edwards, which served as NASA's principal backup for shuttle returns during much of the 30-year orbiter program in case of bad weather over Cape Canaveral.

'THERE'S MY SPACESHIP'

On its way to Edwards on Thursday, Endeavour and its carrier jet performed a fly-by pass over Tucson, Arizona, in tribute to former Congresswoman Gabrielle Giffords and her husband, Mark Kelly, the retired astronaut who commanded Endeavour's final flight on his last mission in late May 2011.

Kelly and Giffords, who is still recuperating from a gunshot wound to the head suffered in an attempt on her life last year, watched the flyover from the roof of a Tucson parking garage.

"When it came into view, Mark said, 'There's my spaceship!'" recounted a former aide, C.J. Karamargin, who joined the couple for the event. "Gabby was just elated, hooting and hollering like the rest of us were."

After its arrival at Los Angeles, Endeavour will undergo preparations to be moved next month through city streets from the airport to its permanent home at the California Science Center in downtown Los Angeles, where the shuttle will be put on public display starting October 30.

To make way for the mammoth orbiter along its 12-mile (19-km) route to the museum, crews are cutting down nearly 400 trees, raising overhead utility wires and temporarily removing hundreds of utility poles, street lights and traffic signals. The science center has agreed to plant 1,000 new trees to replace those scheduled for removal.

Endeavour is the second of NASA's three surviving shuttles to be sent to a museum. The oldest surviving shuttle, Discovery, is on display at the Smithsonian Institution's Steven F. Udvar-Hazy Center outside Washington.

Atlantis, which flew NASA's 135th and final shuttle mission in July 2011, will be towed down the road to the Kennedy Space Center Visitor Complex in November.

NASA lost a fourth shuttle, Columbia, in another fatal accident in 2003. That shuttle was not replaced. A shuttle test vehicle, Enterprise, which has never flown in space, was delivered to a New York City museum.

On its way from Edwards to the Los Angeles, Endeavour and its carrier jet are expected to fly in low over San Francisco Bay and the California state Capitol in Sacramento before heading south for additional flyovers of such landmarks as Disneyland, the Griffith Observatory, the Hollywood sign, Malibu Beach and Los Angeles City Hall. (READ MORE)