Eugene Andrew Cernan, known to friends as "Gene" and to history as the last man to set foot on the Moon, passed away on Monday, surrounded by his family. He was 82. His cause of death has not been disclosed, but the family's representative confirmed it was an ongoing health issue rather than a sudden fatality.

Born in Chicago in 1934, Cernan was an accomplished pilot and a crew member on three historic NASA spaceflights. In 1966, he traveled off Earth for the first time with fellow pioneer Tom Stafford on Gemini IX-A. The pair were originally the mission's backup crew, but stepped up after the two original crew members tragically died in a jet crash. During this flight, Cernan completed a spacewalk in low Earth orbit that lasted over two hours.

In May 1969, Cernan served as the lunar module pilot for Apollo 10, which was considered the "dress rehearsal" for Apollo 11's momentous landing on the Moon two months later, on July 20. Cernan was paired with Stafford again for this mission, and together with command module pilot John Young, the two astronauts practiced crucial sequences in the docking, descent, and ascent maneuvers required to land on the Moon.

They also escaped a terrifying brush with death after feeding the wrong commands into the module's computer system, causing the spacecraft to roll violently. Without the team's calm-under-pressure, Apollo 10 would have crashed into the Moon.

Cernan in 1969. Image: NASA