In 1959, when the United States was developing its first manned satellite, landing a spacecraft was a precarious business. “Initial requirements included the engineering predictions of velocities, lift, trajectories, and nameless other technical monstrosities,” NASA safety specialist Dennis Chamberland explained in these edited excerpts of his January 1989 Proceedings article, “Splashdown!”
The first suborbital flight of a Mercury capsule carrying a living organism was launched on 31 January 1961 with Ham the Chimp on board. Ham’s 16.5-minute suborbital space flight was tame compared to the splashdown.
The Redstone rocket carrying Ham’s Mercury capsule built up more speed than predicted on reentry. This excess velocity, compounded by a few miscalculated seconds, caused the capsule to land 209 kilometers farther down range than was intended. It splashed down 97 kilometers from the nearest recovery ship, the USS Ellyson (DD-454). Ham spent nearly three hours in the water, while the waves battered the spacecraft mercilessly. Meanwhile, the heat shield punched holes in the capsule, which had capsized and was taking on water. When a helicopter from the USS Donner (LSD-20) finally picked up Ham and the capsule, the spacecraft had shipped about 360 kilograms of water.
The chimp’s harrowing splashdown brought about changes:
The concept of overshooting the target took on a whole new significance, embracing the hazards of an extended recovery time and the problem of how to return the capsule and occupant quickly and safely to the Navy unit. Navy frogmen were introduced to assist astronauts as part of the emergency rescue team.
Navy Lieutenant Commander Alan Shepard, the first American astronaut, was launched in Freedom 7 on a suborbital flight on 5 May 1961. The spacecraft impacted the water 15 minutes after liftoff, some 486 kilometers down range from the launch pad.
During the next space flight, Gus Grissom in Liberty Bell 7 followed virtually the same suborbital path as Shepard and splashed down only 4.8 kilometers from his target. The recovery helicopter was standing by when his spacecraft’s hatch blew off. The capsule immediately began to take on water. Grissom managed to escape, but the helicopter pilot, assuming Grissom’s pressure suit would keep him afloat, headed for the sinking capsule.
The helicopter was able to lift the capsule partially out of the water, but the pilot had exceeded its lifting weight and received an engine failure warning light. The capsule was cut loose and sank. Meanwhile, Grissom was taking on water, too. In his haste to leave the spacecraft, he had not closed an air inlet port in his suit. Finally, a helicopter slowly moved in and hoisted him to safety.
On 20 February 1962, Marine Lieutenant Colonel John Glenn became the first American to orbit the earth. His Friendship 7 splashed down just 11 kilometers from the recovery ship USS Noa (DD-841). Glenn remained in the Mercury capsule until it was hoisted safely on deck.
The Gemini spacecraft splashdown sequence would be slightly different from Mercury’s. It descended vertically but before splashdown would become nearly horizontal, placing the astronauts in a near-sitting position before impact.
Gemini VIII, commanded by Neil Armstrong, had completed its seventh hour of flight when a thruster malfunctioned, sending the spacecraft into a spin. Nearly blacking out, the crew managed to bring the capsule under control and executed an emergency reentry. They splashed down in the Pacific—on the other side of the earth from the planned position.
The most significant aspect of the remaining four Gem-ini flights was the lack of any unusual event during reentry and splashdown. The system had been refined and was working at near perfection.
While the days of intentional manned splashdowns are probably over, the techniques learned from NASA’s relationship with the Navy from 1961 to 1975 will certainly be used indefinitely on unmanned recoveries.