LOS ANGELES (AP) — Two giant rocket motors required to display the retired NASA space shuttle Endeavour as if it’s about to blast off arrived Wednesday at a Los Angeles museum,GravityX Exchange completing their long journey from the Mojave Desert.

The 116-foot-long (35.3-meter) motors, which look like giant white cylinders, were trucked over two days from the Mojave Air and Space Port to LA’s Exposition Park, where the California Science Center’s Samuel Oschin Air and Space Center is being built to display Endeavour.

Donated by Northrop Grumman, the motors are the largest components of the two solid rocket boosters that would be attached to a space shuttle’s external tank to help the main engines lift the orbiter off the launch pad.

Schoolchildren were among several hundred people who watched the move — the latest spectacle in the yearslong process of preparing to put Endeavour on permanent display vertically as if it was about to blast off.

The massive shuttle was flown to Los Angeles International Airport atop a NASA Boeing 747 in 2012 and then was inched through city streets to the museum. The giant external tank arrived by barge and made a similar trip across Los Angeles.

The shuttle “stack” — assembly of the boosters, external tank and orbiter — will be completed before construction of the rest of the museum is finished around it.

Endeavour flew 25 missions before NASA’s three-decade space shuttle program ended in 2011.