ALAN BEAN: Alan Bean, a former Navy test pilot, stepped onto the moon's surface after Pete Conrad, while both were on the Apollo 12 flight in November 1969. Bean returned to space in July 1973, when he commanded a three-man flight to the orbiting space research station Skylab, the forerunner of the International Space Station. Bean and two other crewmembers set a world record during their Skylab mission, traveling 24.4 million miles over 59 days. Bean, who died in 2018 at age 86, later in life took to painting to tell the story of NASA's Apollo missions.

REUTERS/Stringer 

ALAN SHEPARD: Alan B. Shepard Jr. was one of the nation's original seven Mercury astronauts named in 1959 and the first American to fly in space. Shepard, as commander of the Apollo 14 mission, became the fifth man to walk on the moon, in February 1971. According to NASA, Shepard and Lunar Module pilot Edgar Mitchell had two excursions on the moon that lasted a total of nine hours. During their time on the moon, Captain Shepard, wielding a makeshift 6-iron, hit two golf balls, televised back to Earth, one of which traveled "miles and miles and miles," as he put it, in lunar gravity only one-sixth that of the Earth. Shepard, a Navy vet, died in 1998 at the age of 74 after a long illness.

NASA/Handout via REUTERS