1965: An astronaut in space holds a conversation with an aquanaut underwater, marking another milestone in human communication.

Astronaut Gordon Cooper, orbiting the Earth with Pete Conrad in Gemini 5, hooked up by radiotelephone with an old pal, astronaut-turned-aquanaut Scott Carpenter, who was living and working 205 feet beneath the surface of the Pacific Ocean near La Jolla, California, aboard Sealab II.

The two men had known each other since 1959, when they were among the seven pilots chosen by NASA to be America’s first Project Mercury astronauts. Carpenter, a former Navy pilot, had already been in space, the solo astronaut on a mistake-plagued, three-orbit flight aboard Aurora 7 that resulted in his effectively being grounded.

He was on leave from the space agency when he joined the Navy’s Sealab II project as training officer. Carpenter eventually resigned from NASA in 1967. He retired from the Navy in 1969.

Cooper and Conrad, meanwhile, were nearing the end of an eight-day orbital mission to test human endurance in space. Eight days was recognized as the time needed to travel to the moon and back. (Five days was the longest Soviet space flight before then, and the American record was four days. By years’ end, American astronauts would complete a 14-day mission in space.)

See Also:

Photo Gallery
NASA’s Glorious History of Training Astronauts

Feature Package
NASA: 50 Years of Towering Achievement

The radio hookup was partly a gimmick, to take advantage of Carpenter’s astronaut status to publicize the Sealab II project. But it was also a method of testing the effectiveness of an underwater electronics lab installed aboard the submersible.

Gemini 5 was not the only long-distance call made from Sealab II. The Navy aquanauts also spoke with President Lyndon Johnson at the White House and with Jacques Cousteau’s Conshelf III team, French colleagues conducting a similar underwater-habitat test off Cap Ferrat in the Mediterranean Sea.

Following their chat with Carpenter, Cooper and Conrad readied Gemini 5 for its return to Earth and splashed down in the very same Pacific Ocean later that day.

Thirty years later, in 1995, Carpenter recreated his seabed-to-space call, chatting with astronauts aboard the space shuttle Endeavour while staying at Jules’ Undersea Lodge off Key Largo, Florida.

Source: Various

Top photo: Sealab II (Courtesy U.S. Navy)
Bottom photo: Astronauts Pete Conrad (left) and Gordon Cooper (Courtesy NASA)

This article first appeared on Wired on Aug. 29, 2008.