Wednesday is the 50th anniversary of the worlds first spacewalk, by cosmonaut Alexei Leonov. Since then, astronauts have accomplished many milestones beyond the confines of a spacecraft

Credit: NASA

Today marks 50 years since Alexei Leonov of the former Soviet Union floated beyond the bounds of his Voskhod 2 space capsule in the worlds first spacewalk. During his 10-minute extravehicular activity (EVA), Leonov changed the way humans exist in the universe. No longer were we bound to the ground of our home planet, or even the manmade grounds of our space vehicleswe could be in the universe on our own, with only the thin protection of a spacesuit between our skin and the raw expanse of the cosmos. The ability to fly outside a spacecraft was also critical for many of humankinds greatest achievements in space, such as walking on the moon, repairing the Hubble Space Telescope and other satellites in orbit, and assembling the International Space Station.

These days NASA, the Russian Federal Space Agency and even the China National Space Administration, are old pros at managing spacewalkssometimes complicated maneuvers that last hours and feature multiple astronauts. But back on March 18, 1965, Leonov was flying, literally, into unknown territory. As he told The Smithsonians Air and Space Magazine in 2005, even his family did not know he would be making the spacewalk until it happened, prompting his four-year-old daughter, watching him on TV, to wail, Please tell Daddy to get back inside. w. And the lack of atmospheric pressure out in space caused Leonovs suit to deform in unexpected ways, making it difficult for him to reenter his spacecraft and putting his life at risk. He managed, however, and racked up an important success in the space race, beating the Americans by less than three months (Ed White made the first U.S. spacewalk on June 3, 1965, from Gemini 4).

We have come a long way since then, and still have a long way to go, in our quest to live and work seamlessly in space. Below are the greatest hits of spacewalking historyyou can see a slideshow of these feats here: 50 Years of Walking Through Space [Slideshow]

The Greatest Spacewalking Feats of All Time

The First Spacewalk March 18, 1965 Soviet cosmonaut Alexi Leonov became the first person to float outside a spacecraft during a 10-minute excursion on the Voskhod 2 mission. His spacesuit deformed in the vacuum of space, forcing Leonov to vent oxygen out of his suit to squeeze himself back inside.

The First American Spacewalk June 3, 1965 NASA astronaut Edward H. White, II, doubled Leonovs time when he made the U.S.s first spacewalk less than three months later. White floated outside his Gemini 4 capsule for 21 minutes, using a zip gun that ejected pressurized oxygen to maneuver himself around in space. White enjoyed using the gun, but subsequent spacewalkers reported that it was difficult to operate, so it was rarely used after the Gemini program.

The First Untethered Spacewalk February 7, 1984 Until the space shuttle Challengers STS-41B mission, spacewalkers were tethered to their spaceships by a long cord. These tethers also limited their movements, however, and sometimes made maneuvering difficult. Astronaut Bruce McCandless II was the first to test out the Manned Maneuvering Unita type of jetpack that he wore on his back to steer himself around. Unchecked by a tether, McCandless flew 100 meters out from the shuttles cargo baythe farthest a spacewalker had ever been before.

Hubble Repair Spacewalks December 5-9, 1993 The Hubble Space Telescope was launched to much fanfare in April 1990, but soon after it became apparent that the observatorys optics were flawed. To save the $2.5 billion telescope, NASA sent seven astronauts on a rescue mission onboard the shuttle Endeavour. Four of the STS-61 crew F. Story Musgrave, Jeffrey A. Hoffman, Kathryn C. Thornton and Thomas D. Akerscompleted five spacewalks in five days to install a new primary camera and corrective optics package for the telescope. Their efforts paid offthe telescope delivered on its promise to reveal the cosmos in brand new waysand four more servicing missions followed in the coming years to upgrade the observatory, which could operate through 2020.

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50 Years of Walking in Space: Spacewalkings Greatest Hits