Gemini 9 lifts off on a three-day mission to complete the still unfulfilled docking objectives of the Gemini program. The flight has already seen significant problems, not the least of which is the death of the originally-assigned crew, Elliott See and Charles Bassett, in an accident involving T-38 training jets. The backup crew, Thomas Stafford and Gene Cernan, fly Gemini 9 instead, but find that their rendezvous/docking target is still trapped in the aerodynamic shroud that protected it during launch (the shroud would normally have been jettisoned). Furthermore, a spacewalk has been written into the mission plan, requiring Cernan to leave Gemini and go to the rear of the vehicle to unstow and test a “jetpack” (an early prototype of the Manned Maneuvering Unit that will finally see use in the space shuttle program in the 1980s). The spacewalk becomes a two-hour ordeal which leaves Cernan exhausted, thanks to the lack of handholds on the exterior of the Gemini capsule. The flight ends after three days in space.