<p><strong>U.S.&nbsp;astronaut <a href="http://www.jsc.nasa.gov/Bios/htmlbios/shepard-alan.html">Alan Shepard</a> poses in his silver pressure suit in a 1963 picture from the early days of <a href="http://www-pao.ksc.nasa.gov/history/mercury/mercury.htm">NASA's Mercury space program</a>. Thursday marks the 50th anniversary of Shepard becoming the first American in space, when he completed a short suborbital voyage aboard the Freedom 7 spacecraft.</strong></p><p>Less than a month before, Soviet cosmonaut Yuri Gagarin had become the first human in space with his successful orbital flight aboard the Vostok 1 spacecraft. (See <a href="http://news.nationalgeographic.com/news/2011/04/pictures/110412-yuri-gagarin-50th-anniversary-first-human-space-pictures/">"Yuri Gagarin: First Human Space Flight in Pictures."</a>)</p><p>Over the decades, the U.S. space suit has evolved as astronauts' duties have become more complicated. The suit Shepard wore during his 16-minute flight was designed by aerospace manufacturer B.F. Goodrich. Called the Mark-IV, it was essentially a converted Navy-pilot suit, said Bill Ayrey, a space suit historian with <a href="http://www.ilcdover.com/">ILC Dover</a> in Delaware.</p><p>"Although it was referred to as a space suit by many at the time, it was actually a modified pressure suit," Ayrey said. "When they were looking for a space suit for Mercury, they were just looking for a suit that would hold pressure, in case they lost pressure aboard the capsule."</p><p>Later space suits, intended to withstand life outside the spacecraft, also kept astronauts well ventilated and at a comfortable temperature as well as safe from radiation and micrometeorite impacts.</p><p><em>—Ker Than</em></p>

Alan Shepard: First American in Space

U.S. astronaut Alan Shepard poses in his silver pressure suit in a 1963 picture from the early days of NASA's Mercury space program. Thursday marks the 50th anniversary of Shepard becoming the first American in space, when he completed a short suborbital voyage aboard the Freedom 7 spacecraft.

Less than a month before, Soviet cosmonaut Yuri Gagarin had become the first human in space with his successful orbital flight aboard the Vostok 1 spacecraft. (See "Yuri Gagarin: First Human Space Flight in Pictures.")

Over the decades, the U.S. space suit has evolved as astronauts' duties have become more complicated. The suit Shepard wore during his 16-minute flight was designed by aerospace manufacturer B.F. Goodrich. Called the Mark-IV, it was essentially a converted Navy-pilot suit, said Bill Ayrey, a space suit historian with ILC Dover in Delaware.

"Although it was referred to as a space suit by many at the time, it was actually a modified pressure suit," Ayrey said. "When they were looking for a space suit for Mercury, they were just looking for a suit that would hold pressure, in case they lost pressure aboard the capsule."

Later space suits, intended to withstand life outside the spacecraft, also kept astronauts well ventilated and at a comfortable temperature as well as safe from radiation and micrometeorite impacts.

—Ker Than

Photograph courtesy NASA

Photos: Space Suit Evolution Since First NASA Flight

See how U.S. space suits have advanced since Alan Shepard made the first U.S. human spaceflight 50 years ago in modified Navy pilot gear.

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