In 1965, the first spacewalk took place as Soviet cosmonaut Alexei Leonov left his Voskhod 2 capsule and remained outside the spacecraft for 20 minutes, secured by a tether. Leonov floated out into the vacuum of space on March 18, 1965, beating America's first spacewalker, Gemini 4's Edward White II, by just 2 1/2 months. Leonov is now 80; White died in the Apollo 1 fire on the launch pad in 1967.

Russian Cosmonaut

Lt. Col. Alexei Leonov turns a somersault in outerspace in weightlessness outside Soviet space craft Voskhod-2 during 10 minutes of free flight during second of 16 orbits of Earth. Soviet officials presented this picture on television in Moscow, March 18, 1965. Projection at right support a movie camera. (AP Photo)

Spacewalking always carries high risk; a puncture by a micrometeorite or sharp edge, if big enough, could result in instant death. Leonov, could barely get back into his spacecraft in 1965. He had to vent precious oxygen from his suit in order to fit through the hatch. Decades passed before his peril came to light.

U.S. GEMINI 4 ASTRONAUT WHITE

Astronaut Ed White faces the Gemini 4 capsule during his 20-minute space "walk" on June 8, 1965. In his right hand, White holds his oxygen space gun to maneuver around the capsule. A 35-mm camera is attached to the space gun. Astronaut James McDivitt took this photograph with a Hasselblad camera. (AP Photo/NASA/James McDivitt)

Air Force Lt. Col. Edward White II

Air Force Lt. Col. Edward White II, who died at Cape Kennedy with fellow astronauts Air Force Lt. Col. Virgil I. Grissom and Navy Lt. Comdr. Roger B. Chaffee, is shown as he clambered from the Gemini 4 spacecraft to become the first American to walk in space. The space walk came during his 1965 flight with James McDivitt. (AP Photo)

U.S. TITAN GEMINI IV LIFT OFF

The Titan II rocket carrying the Gemini IV spacecraft on its nose lifts from launch pad LC-19 at Cape Kennedy, Fla., at 10:15 am, EST, June 3, 1965. The crew members of the Gemini IV mission are astronauts James H. McDivitt, commander, and Edward H. White II, pilot. On their third orbit, White left the vehicle for a 20-minute "walk" in space. (AP Photo)

In 1966, two Gemini flights ended up with aborted spacewalks. Gemini 11 spacewalker Richard Gordon, was blinded by sweat. Gemini 9 spacewalker Gene Cernan breathed so heavily and sweated so much that fog collected inside his helmet visor and froze.

During NASA's old shuttle program, spacewalks occasionally were stymied by stuck hatches and ripped gloves.

In early March of this year, spacewalking astronauts successfully completed a three-day cable job outside the International Space Station, routing several-hundred feet of power and data lines for new crew capsules commissioned by NASA.

As many as four more U.S. spacewalks will be conducted this year — beginning this summer.

Below is a selection of spacewalking missions through the years.

HUMAN SATELLITE

Astronaut Bruce McCandless II, equipped with his nitrogen-propelled manned maneuvering unit (MMU) space walks as far as 300 feet (90 meters) from the Challenger, February 9, 1984. It was the first untethered space walk in history. (AP photo/Nasa)

Space Station

FILE - In this Saturday, May 11, 2013 photo made available by NASA, astronaut Chris Cassidy and Tom Marshburn, not pictured, perform a space walk to inspect and replace a pump controller box on the International Space Station after an ammonia coolant leak was discovered. On Tuesday, Dec. 17, 2013, NASA decided to schedule a series of urgent spacewalks to fix a broken cooling line at the International Space Station. The first is scheduled for Saturday, Dec. 21, 2013. (AP Photo/NASA)

SPACE SHUTTLE

In this image provided by NASA astronaut Scott Parazynski participates in the third space walk Tuesday Oct. 30, 2007 as construction continues on the International Space Station. Various components of the station are visible in the reflections in Parazynski's helmet visor. (AP Photo/NASA)

CHALLENGER MISSION SPACE WALK

Astronaut Bruce McCandless takes a "space walk" using the Manned Maneuvering Unit, Feb. 9, 1984, during the space shuttle Challenger mission. By firing small nitrogen-gas jets from his massive pack, McCandless was able to venture some 300 feet from Challenger without a tether, commonly used by today's shuttle astronauts. (AP Photo/NASA)

Space Shuttle Legacy

FILE - This Friday May 27, 2011 photo provided by NASA shows the sun, a portion of the International Space Station and Earth's horizon in a photograph made by a spacewalker using a fisheye lens during a space walk. (AP Photo/NASA)

Russia Sochi Torch Relay

In this image taken from TV, the Olympic Torch is carried outside the International Space Station (ISS) on a space walk Saturday Nov. 9, 2013. Two Russian cosmonauts Oleg Kotov and Sergei Ryazansky are taking the un-lit torch for the Sochi Winter Olympics on its first historic space walk with the curve of the earth seen in background right, ahead of next year's Winter Olympic Games in Russia. The Torch relay for the Sochi Winter Games began on Oct. 7, 2013, in Moscow, and will pass through many cities that showcase the historical, cultural and ethnic richness of Russia, as well as a short space walk and this torch will be used to light the Olympic cauldron for the games. (AP Photo)

Space Shuttle

In this photo provided by NASA, astronaut Christopher Cassidy, STS-127 mission specialist, is pictured in the center of this wide shot photographed during Endeavour's third space walk of a scheduled five overall for this flight. Cassidy is near The Japanese Experiment Module - Exposed Facility (JEF.) This was Cassidy's first of a scheduled three sessions for him, Wednesday, July 22, 2009. (AP Photo/NASA)

RUSSIA SPACE WALK

Russian Mission Control specialists watch a TV link with the International Space Station as they guide Russian cosmonaut Gennady Padalka and American astronaut Mike Fincke during their space walk, at the Russian Mission Control in Korolyov, outside Moscow, early Thursday, July 1, 2004. Determined to do better than last week, the international space station's two astronauts, Fincke and Padalka ventured back outside on an unusually risky space walk and successfully replaced a bad circuit board. (AP Photo/Ivan Sekretarev)

SHUTTLE CHALLENGER 1984

Shuttle Challenger mission specialist Kathryn Sullivan wears a white cooling garment, Oct. 11, 1984, prior to putting on her space suit. Sullivan is the first woman in the U.S. Astronaut Corp that will space walk. (AP Photo/NASA-TV)

NASA MISSION CONTROL APOLLO 15

Ground controllers watch the space walk by Apollo 15 command module pilot Alfred M. Worden from Mission Control, Manned Spacecraft Center in Houston, Texas, Aug. 5, 1971. The spacewalk appears on the large televison screen in background and on smaller screens around the console. (AP Photo/NASA)

SPACE SHUTTLE

Endeavour astronauts Leroy Chiao, left, and Daniel Barry practice techniques and special tools during a space walk Monday, Jan. 15, 1996 in this image from NASA television. Barry is standing on a portable work station attached to the shuttle's robot arm. (AP Photo/NASA)

See more images of spacewalking and Alexei Leonov

Text from the AP news stories, Spacewalking astronauts finish extensive, tricky cable job and Spacesuit water leak ends spacewalk; astronaut OK, by Marcia Dunn.

Spotlight is the blog of AP Images, the world’s largest collection of historical and contemporary photos. AP Images provides instant access to AP’s iconic photos and adds new content every minute of every day from every corner of the world, making it an essential source of photos and graphics for professional image buyers and commercial customers. Whether your needs are for editorial, commercial, or personal use, AP Images has the content and the expert sales team to fulfill your image requirements. Visit apimages.com to learn more.

Written content on this site is not created by the editorial department of AP, unless otherwise noted.

AP Images on Twitter | AP Images on Facebook | AP Images on Google+