Mercury-Redstone 3 in the context of "Kilometer"

Alan Bartlett Shepard Jr. (November 18, 1923 – July 21, 1998) was an American astronaut. In 1961, he became the second person and the first American to travel into space and, in 1971, he became the fifth and oldest person to walk on the Moon, at age 47.

A graduate of the United States Naval Academy at Annapolis, Shepard saw action with the surface navy during World War II. He became a naval aviator in 1947, and a test pilot in 1950. He was selected as one of NASA's original Mercury Seven astronauts in 1959, and in May 1961 he made the first crewed Project Mercury flight, Mercury-Redstone 3, in a spacecraft he named Freedom 7. His craft entered space, but was not capable of achieving orbit. He became the second person, and the first American, to travel into space. In the final stages of Project Mercury, Shepard was scheduled to pilot the Mercury-Atlas 10 (MA-10), which was planned as a three-day mission. He named Mercury Spacecraft 15B Freedom 7 II in honor of his first spacecraft, but the mission was canceled.

Christopher Columbus Kraft Jr. (February 28, 1924 – July 22, 2019) was an American aerospace and NASA engineer who was instrumental in establishing the agency's Mission Control Center and shaping its organization and culture. His protégé Glynn Lunney said in 1998: "the Control Center today ... is a reflection of Chris Kraft".

Following his 1944 graduation from Virginia Polytechnic Institute and State University with a degree in aeronautical engineering, Kraft was hired by the National Advisory Committee for Aeronautics (NACA), the predecessor organization to the National Aeronautics and Space Administration (NASA). He worked for over a decade in aeronautical research and in 1958 joined the Space Task Group, a small team entrusted with the responsibility of putting America's first man in space. Assigned to the flight operations division, Kraft became NASA's first flight director. He was on duty during America's first crewed spaceflight, first crewed orbital flight, and first spacewalk. At the beginning of the Apollo program, Kraft retired as a flight director to concentrate on management and mission planning. In 1972, he became director of the Manned Spacecraft Center (later Johnson Space Center), following his mentor Robert R. Gilruth, and held the position until his retirement in 1982.

Mercury-Atlas 10 (MA-10) was a cancelled early crewed space mission, which would have been the last flight in NASA's Mercury program. It was planned as a three-day extended mission, to launch in late 1963; the spacecraft, Freedom 7-II, would have been flown by Alan Shepard, a veteran of the suborbital Mercury-Redstone 3 mission in 1961. However, it was cancelled after the success of the one-day Mercury-Atlas 9 mission in May 1963, to allow NASA to focus its efforts on the more advanced two-man Gemini program.