Page "Apollo 16" Paragraph 3

Ken Mattingly had originally been assigned to the prime crew of Apollo 13, but was exposed to the measles through Charles Duke, at that time on the back-up crew for Apollo 13, who had caught it from one of his children.

He never contracted the illness, but was nevertheless removed from the crew and replaced by back-up Jack Swigert three days prior to the launch.

John Young, a captain in the United States Navy, had flown on three spaceflights prior to Apollo 16: Gemini 3, Gemini 10 and Apollo 10, which orbited the Moon.

One of nineteen astronauts selected by NASA in April 1966, Charles Duke had never flown in space before Apollo 16.

He served on the support crew of Apollo 10 and was a capsule communicator for Apollo 11.