In 1984, American astronaut Bruce McCandless II (born 1937) became the first person to leave a spacecraft in space without a tether. He flew out of the payload bay of the space shuttle Challenger on February 7 , 1984, and using a jetpack called a Manned Maneuvering Unit (MMU), flew around the vicinity of the shuttle as an independent satellite of the Earth. Also, in 1990, flying on the space shuttle Discovery, he participated in the d eployment of the Hubble Space Telescope, which soon afterwards returned views of interstellar space never before seen.

Joined the Astronaut Corps from the Navy

Bruce McCandless II was born in Boston, Massachusetts, on June 8, 1937, and attended high school in Long Beach, California. After graduating from high school, he went on to the United States Naval Academy in Annapolis, Maryland. He graduated from th e Naval Academy in 1958 with a bachelor of science degree.

Following his graduation from the Naval Academy (second in a class of 900), McCandless learned to pilot aircraft at the Naval Aviation Training Command based in Pensacola, Florida, and Kingsville, Texas. He received his Navy aviator wings in 1960 an d went on to Key West, Florida, where he underwent aircraft carrier landing training flying F-6A Skyray aircraft.

Next McCandless was assigned to the 102nd Fighter Squadron flying Skyrays and F-4B Phantom II aircraft from the USS Forrestal and the USS Enterprise aircraft carriers. The latter ship participate d in the United States naval blockade of Cuba in the 1960s while McCandless was serving on her.

In 1964, McCandless served as an instrument flight instructor in the 43rd Attack Squadron, based at Apollo Soucek Field at Oceana, Virginia's Naval Air Station. McCandless continued his education at Stanford University in Stanford, California, throu gh the Naval Reserve Officer's Training Corps Unit. There, in 1965, he earned a master of science degree in electrical engineering.

During his time as a Navy aviator, McCandless became an expert pilot, gaining proficiency on almost a dozen aircraft, including jets and helicopters. He joined the National Aeronautics and Space Administration (NASA) astronaut corps in 1966, during the height of the space race in which the United States and the Soviet Union competed to be the first to send humans to the moon. In 1971, McCandless served on the support crew for Apollo 14, the third mission to touch down on t he surface of the moon, and two years later served on the backup crew of the United State's first mission to its first space station, Skylab. Also during this time, McCandless helped to develop the Manned Maneuvering Unit (MMU), which he was later to test fly on a space shuttle mission.

Waited 18 Years for His First Spaceflight

Eighteen years passed between the time McCandless became a member of the astronaut corps and his first flight into space. He was described by his fellow astronauts as something of a loner and appeared to be unwilling to engage in the competitive pol itics that many saw as a necessity for getting assigned to space missions.

A lover of the outdoors, McCandless was also an avid bird-watcher, an activity that sometimes made him the butt of jokes at the astronaut office. He proved the value of his knowledge of birds, however, after a new runway was built at the Kennedy Spa ce Center in the middle of what had been a bird refuge. Sent to study how accidents involving birds could be avoided by NASA pilots, McCandless learned which birds were likely to nest near the runway, which birds would be frightened by aircraft noise, and in what direction they would most likely fly when startled. Armed with this knowledge, McCandless was able to advise his fellow pilots on how and at what times of the day to fly to avoid accidents with birds. Recalled moonwalking astronaut Alan Bean to T homas O'Toole in the Washington Post, NASA pilots took McCandless's suggestions "and never had an accident."

Finally, after 18 years of waiting, McCandless got his chance to fly into space. He did so by serving as mission specialist on the STS-41B space shuttle mission, which flew February 3 to 11, 1984. He was later assigned to a second space mission, STS -31, which flew April 24 to 29, 1990.

Performed the First Untethered Spacewalk

The space shuttle Challenger lifted off from the Kennedy Space Center in Florida on February 3, 1984. This was the tenth space shuttle mission flown. The main tasks for this mission were the deployment of two communication s satellites and to conduct the maiden flight of the MMU. McCandless accomplished this last task, flying each of the mission's two MMUs for the first time, to become the world's first free-flying spacewalker, in effect becoming an independent satellite of the earth. Helping him in this endeavor, and using the MMUs himself, was fellow astronaut Lieutenant Colonel Robert L. Stewart of the United States Army.

To fly independently of the space shuttle, McCandless and Stewart first cycled through the shuttle's airlock and made their way out into the spacecraft's payload bay. There, McCandless attached the MMU, essentially a jetpack, to his spacesuit. Next, he disengaged the MMU from its berth in the payload bay, and became, as he was quoted by Thomas O'Toole in the Washington Post as saying, "the smallest spaceship in history." Flying alongside the shuttle, he circled the globe a t 17,500 miles per hour at an altitude of 150 miles.

After first putting the MMU through its paces in the shuttle's payload bay, McCandless got the go-ahead from mission commander Vance Brand, watching through the shuttle's windows, to take the MMU 150 feet out into space. After completing that maneuv er, McCandless headed back to the shuttle, before getting the go-head to fly 300 feet from the shuttle. As he did so, he compared the sensation to flying a helicopter at 25 times the speed of sound. After returning to the shuttle's payload bay, McCandless practiced docking the MMU to docking adaptors mounted on the payload bay walls. This was to simulate similar maneuvers that would take place when docking with satellites for future repair missions. Following McCandless's lead, Stewart conducted his own M MU flight tests using the same MMU. These tests were equally successful, and the two headed back inside the shuttle.

Performed an Unscheduled Test of Rescue Procedures

Two days later, McCandless and Stewart again left the shuttle's airlock to conduct MMU tests. This time they used a second MMU along with the first. Both MMUs were mounted in the shuttle's payload bay. During this second venture outside of the space craft, or Extra Vehicular Activity (EVA), the two astronauts conducted an unscheduled test of the procedures that would be used to rescue an astronaut who had unintentionally floated away from the shuttle. This came about when a foot restraint that McCand less was using to secure himself while completing simulated repairs on a mockup of a satellite in the payload bay came loose. The foot restraint floated free of the payload bay, and shuttle commander Brand, following instructions radioed by McCandless, ma neuvered the shuttle so that McCandless could reach out and retrieve the restraint. McCandless joked as he retrieved the restraint that his shuttle crew made pickups as well as deliveries.

After completing their second EVA of the mission, and before going back inside, McCandless and Stewart took a telephone call from President Ronald Reagan, who asked them what it was like working in space without tethers. Replied McCandless, accordin g to Thomas O'Toole in the Washington Post, "The view is simply spectacular, and we're literally opening up a new frontier in what man can do in space."

Instrumental in the Development of Untethered EVAs

Forty-six years old at the time of his spacewalks, and a captain in the Navy, McCandless had been helping to develop the MMU since 1968. The device had gone through numerous design changes, and during this time McCandless had also lobbied NASA and C ongress to convince them to fund it. Many decisionmakers had thought that the backpack would be too expensive and too impractical to be of use to the United States space program, but McCandless proved them wrong on his historic flight.

The first incarnation of the MMU had been flown aboard the Gemini 9 spacecraft in 1966 and was to have been tested by astronaut Gene Cernan (who later became the last person to walk on the surface of the moon). Cernan exit ed Gemini 9, and, attached to the spacecraft with a tether, worked his way to the back of the spacecraft, where the backpack was stowed. There he found that the design of his spacesuit restricted his freedom of movement so much that he was unable to properly attach the backpack and test it.

A redesign of the backpack was finally successfully tested inside the Skylab space station in the early 1970s. By the time McCandless strapped on his MMU in 1984, the machine had been redesigned 11 times, 9 of those times at McCandless's instigation . The machine cost $60 million to design and build. McCandless himself participated materially in the design process, on one occasion inventing a way the backpack could be used to stabilize a satellite stranded in orbit. McCandless's invention prompted on e of his colleagues at NASA to call him a "thorough, methodical and brilliant electronics genius," according to Thomas O'Toole in the Washington Post.

The successful tests of the MMUs by McCandless and Stewart on STS-41B were bright spots on what had been a disappointing mission up until that point. The shuttle's primary mission was to deploy a pair of communications satellites. The release of the satellites from the shuttle's payload bay went off without a hitch, but the booster rocket that was supposed to send the satellites into a higher orbit malfunctioned, stranding the expensive satellites in useless orbits.

After 191 hours in space, four of which he spent flying the MMUs, McCandless returned to Earth aboard the Challenger on February 11, 1984, touching down with his crewmates at the Kennedy Space Center's shuttle runway. It w as the first time a shuttle had landed at the Space Center. In 1987, between his two space shuttle flights, McCandless earned his second masters degree, in business administration, from the University of Houston at Clear Lake.

Another Historic Space Mission

In 1990, McCandless flew on another historic shuttle flight when the shuttle Discovery lifted off on shuttle mission STS-31 on April 24. This mission launched the Hubble Space Telescope, the pioneering orbiting observatory that subsequently returned the clearest images of the most distant objects ever observed by human beings. This mission also set an altitude record for a space shuttle of 380 miles.

The Space Telescope almost required rescuing by McCandless and fellow astronaut Kathy Sullivan. The telescope's two 20-foot solar panels failed to unfurl properly, and McCandless and Sullivan were ordered into their spacesuits and told to prepare to unfurl the solar panels manually. But, while McCandless and Sullivan waited in the shuttle's airlock for the last of the air to be pumped out so that they could venture out into the payload bay, ground controllers managed to solve the problem. McCandless and Sullivan were told to repressurize the airlock and go back inside.

After 76 orbits of the earth, during which McCandless and his crewmates spent 121 hours in space, Discovery touched down at the Edwards Air Force Base in California, on April 29, 1990. By the time McCandless retired from t he astronaut corps (and the Navy as a captain), he had logged more than 312 hours in space on two separate missions aboard the space shuttles.

Hobbies for McCandless include, not surprising for an astronaut, flying airplanes and scuba diving, perhaps the two experiences that come closest to replicating the experiences of being in space without actually going there. He is also an electronic s and photography enthusiast and enjoys cross-country skiing. An avid bird-watcher, McCandless is a past president of the Houston Audubon Society. He is married to the former Bernice Doyle, and they have two grown children.

Further Reading

• Cernan, Eugene, and Don Davis, The Last Man on the Moon, St. Martin's Press, 1999.
• Aviation Week and Space Technology, February 13, 1984; April 30, 1990.
• Christian Science Monitor, February 8, 1984.
• New York Times, April 25, 1990.
• Washington Post, February 7, 1984; February 10, 1984.
• "Astronaut Bio: Bruce McCandless II," NASA, http://www.jsc.nasa.gov (March 11, 2003).