Neil Armstrong - the first man to walk on the moon - has passed away at the age of 82 following complications resulting from cardiovascular procedures.
Armstrong's famous words: "That is one small step for (a) man, one giant leap for mankind," spoken on July 20, 1969 during the 1969 Apollo 11 mission instantly became a part of American history and lore forever.
"Neil Armstrong was a hero not just of his time, but of all time," President Barack Obama said via Twitter. "Thank you, Neil, for showing us the power of one small step."
Apollo 11 lunar module pilot and fellow moonwalker Buzz Aldrin also expressed his condolences on Armstrong's passing.
"Neil and I trained together as technical partners but were also good friends who will always be connected through our participation in the Apollo 11 mission," said Aldrin. "Whenever I look at the moon it reminds me of the moment over four decades ago when I realized that even though we were farther away from earth than two humans had ever been, we were not alone."
Neil A. Armstrong was born Aug. 5, 1930, in Wapakoneta, Ohio. He earned an aeronautical engineering degree from Purdue University and a master's in aerospace engineering from the University of Southern California. He was a naval aviator from 1949 to 1952 and flew 78 combat missions during the Korean War.
In 1955 he joined the National Advisory Committee for Aeronautics (NACA), NASA's predecessor, as a research pilot at Lewis Laboratory in Cleveland. Armstrong later transferred to NACA's High Speed Flight Research Station at Edwards AFB, Calif. As project pilot, he was in the forefront of the development of many high-speed aircraft, including the X-15, which flew at 4,000 mph.
Armstrong was selected as an astronaut in 1962. His first space flight was Gemini 8, which he commanded. He was the first civilian to fly a U.S. spacecraft. With fellow astronaut David R. Scott, Armstrong performed the first docking in space, with an Agena target satellite. Less than an hour later their spacecraft began an unplanned rolling motion. After undocking, it increased to one revolution per second. One of the Gemini's 16 thrusters had stuck open because of an electrical short circuit.
Armstrong used re-entry thrusters to control the capsule, and after a 30-minute struggle, it was stabilized. Flight rules required a return to Earth after use of the re-entry thrusters, so the crewmembers fired retrorockets that sent Gemini 8 to a contingency landing zone in the Western Pacific.
Apollo 11 lifted off on July 16, 1969, with Armstrong, Aldrin and Mike Collins aboard. Collins remained in lunar orbit in the command module while Armstrong and Aldrin descended in the lunar module they had named Eagle to their historic landing on the moon's surface.
"Houston, Tranquillity Base here. The Eagle has landed," Armstrong said, telling a tense and waiting Earth that men had finally reached the lunar surface.
He and Aldrin spent about two hours exploring, gathering more than 50 pounds of moon rocks and setting up three scientific experiments. The next day, after 21 hours and 37 minutes on the moon, they fired Eagle's engine to begin the return to Collins and the command module.
The crew returned to Earth, landing near the USS Hornet in the Pacific after a mission of just over eight days. President Richard M. Nixon was on the aircraft carrier's deck to welcome them.
"This is the greatest week in the history of the world since the creation," Nixon told the three.
After 16 days in quarantine to protect Earth from any returned moon germs, the crew went on U.S. and international tours. Millions greeted them as heroes.
Armstrong is survived by his wife, two sons, a stepson, a stepdaughter, 10 grandchildren, and a brother and sister.