A space shuttle main engine (SSME) is on display near the space shuttle Endeavour at the California Science center's Samuel Oschin Space Shuttle Endeavour Display Pavilion, Tuesday, Oct. 30, 2012, in Los Angeles. Endeavour, built as a replacement for space shuttle Challenger, completed 25 missions, spent 299 days in orbit, and orbited Earth 4,671 times while traveling 122,883,151 miles. Photo Credit: (NASA/Bill Ingalls)