It's a delicate operation that will never be repeated: installing a 6,000-pound payload into a space shuttle.
"It's a really complex move," said Jeffrey Rudolph, president of the California Science Center. "It's never been done outside Kennedy Space Center."
That complex move is now being done inside the California Science Center, where Space Shuttle Endeavour has been on display since she made her historic journey through the streets of Los Angeles two years ago.
On Thursday in the shuttle's "Go for Payload" phase, the 1,000-square-foot SPACEHAB, which served as a place for the astronauts to both work and live, was slowly and carefully lifted by a crane into Endeavour's massive payload bay -- no easy feat considering the tight quarters and the delicate nature of the payload doors.
They are made of very lightweight composite material designed to operate in weightless space, not on earth under gravitational pull.
The next step will be even trickier: moving Endeavour to its permanent home next door and lifting it to a vertical position so it can be displayed in launch position.
The remaining two phases, "Go for Stack" and "Go for Launch, will end with the launch position in 2018.
"You'll be able to see in, and we want people to see what it was really like on a launch and what it carried with it," Rudolph said.
Visitors will be able to see the payload bay installation thanks to cameras mounted above and inside the shuttle which transmit to monitors below.
Allowing the public to see as much of the space shuttle as possible is important to former astronaut Barbara Morgan. She served on Endeavour and hopes it will inspire the next generation of scientists and explorers.
"They are so excited to be a part of this," Morgan said. "I think that inspires these kids to know these are things they can do too."
Taking a scissor lift up for a better view of the shuttle Endeavour cargo bay
Lifting the SpaceHab into Shuttle Endeavour's cargo bay @casciencecenter