Neil Armstrong, the first man to walk on the moon, has undergone cardiac bypass surgery but is \"doing great\" following the procedure, his wife said. Armstrong had just celebrated his 82nd birthday when a stress test Monday in a Cincinnati area hospital revealed problems, and on Tuesday surgeons performed a quadruple bypass. Fellow Apollo astronaut Gene Cernan told NBC News Armstrong\'s wife told him her husband\'s spirits were high and doctors were confident there would be no problems with recovery. In 1969 Armstrong and fellow Apollo 11 astronaut Buzz Aldrin landed on the moon, with Armstrong descending a ladder to place the first human footprint on the lunar surface, declaring, \"That\'s one small step for a man, one giant leap for mankind.\" After his Apollo mission Armstrong had a brief tenure at the Pentagon\'s Office of Advanced Research and Technology, then became an engineering professor at the University of Cincinnati in his native state of Ohio. Armstrong, always a private man, has chosen to maintain a low profile in public life. In a statement, NASA Administrator Charles Bolden said the space agency \"wishes Neil Armstrong the very best for a quick recovery from surgery.\"