HOUSTON — NASA astronaut Bruce McCandless, the first person to fly freely and untethered in space, has died. He was 80.

McCandless died Thursday in California, NASA's Johnson Space Center announced Friday. No cause of death was given.

He was famously photographed in 1984 flying with a hefty spacewalker's jetpack, alone in the cosmic blackness above a blue Earth. He traveled more than 300 feet away from the space shuttle Challenger during the spacewalk.

This 1982 photo made available by NASA shows astronaut Bruce McCandless II, wearing a Shuttle Extravehicular Activity (EVA) Suit with Manned Maneuvering Unit (MMU) in Houston. Courtesy of NASA

McCandless said he wasn't nervous about the historic spacewalk.

"I was grossly over-trained. I was just anxious to get out there and fly. I felt very comfortable ... It got so cold my teeth were chattering and I was shivering, but that was a very minor thing," he told the Daily Camera in Boulder, Colorado, in 2006.

McCandless helped develop the jetpack and was later part of the shuttle crew that delivered the Hubble Space Telescope to orbit.

McCandless also served as the Mission Control capsule communicator in Houston as Neil Armstrong and Buzz Aldrin walked on the moon in 1969.

Born in Boston, McCandless graduated from Woodrow Wilson Senior High School in Long Beach, California. He graduated from the Naval Academy, earned a master's degree in electrical engineering from Stanford University and a master's degree in business administration from the University of Houston at Clear Lake in 1987.

This Feb. 7, 1984, photo released by NASA shows Astronaut Bruce McCandless II leaning out into space as his feet are anchored mobile foot restraint connected to the remote manipulator system. Courtesy of NASA

He was a naval aviator who participated in the Cuban blockade in the 1962 missile crisis. McCandless was selected for astronaut training during the Gemini program, and he was a backup pilot for the first manned Skylab mission in 1973.

Survivors include his wife, Ellen Shields McCandless of Conifer, Colorado, two children and two grandchildren.

Sen. John McCain, R-Ariz., said he was "deeply saddened" by McCandless's death, and he recalled attending the United States Naval Academy together as both were members of the Class of 1958.

“As an undistinguished graduate of that class, I always looked up to Bruce," McCain said, "not only for his incredible intellect, but also for his character and integrity, which embodied the highest values of the United States Navy."