Forty-six years ago this month, NASA Astronauts John W. Young and Michael Collins completed the highly successful mission of Gemini 10. Among other accomplishments, the Gemini 10 crew established a new manned spaceflight record when they rode their Gemini-Agena spacecraft to an altitude of 412 nm above the Earth.
The Gemini Program consisted of ten manned spaceflights flown in a twenty month period starting in March of 1965. Gemini pioneered key technologies required to land men on the Moon including space navigation, rendezvous, docking, orbital maneuvering, long-duration spaceflight and extra-vehicular activity (EVA). Without Gemini, the United States would not have achieved the goal of landing men on the Moon before the end of the 1960’s.
Gemini-Titan 10 (GT-10) was launched from LC-19 at Cape Canaveral, Florida on Monday, 18 July 1966. Lift-off time was 22:20:26 UTC. Roughly 100 minutes earlier, an Agena Target Vehicle (ATV) had been launched from LC-14 into a 162 nm circular parking orbit. Gemini 10 successfully rendezvoused and docked with the ATV at 04:15:00 UTC on Tuesday, 19 July 1966.
Using the Agena’s restartable rocket motor, the docked Gemini-Agena combination was boosted into a 412 nm x 159 nm elliptical orbit. This trajectory exposed the astronauts to flight through portions of the Earth’s radiation belts. Dosimeter measurements revealed that radiation levels at apogee did not constitute a significant health issue for the astronauts. While docked with the Agena, Collins conducted a 49-minute stand up EVA starting at 21:44:00 UTC on 19 July.
After several more burns of the Agena rocket motor, the astronauts undocked from the ATV at 19:00:00 UTC on Wednesday, 20 July 1966. These Agena-aided maneuvers placed Gemini 10 in a position to later use its own orbital maneuver system to complete a rendezvous with the Gemini 8 Agena Target Vehicle at an orbital altitude of 204 nm. This event marked the first time in spaceflight history that a spacecraft successfully rendezvoused with two separate vehicles on the same mission.
At 23:01:00 UTC on 20 July, Collins started a 39-minute EVA in which he floated over to examine the Gemini 8 ATV. He had difficulty trying to hold on to the vehicle, but was able to retrieve a micrometeorite collector for analysis back on Earth. Collins also used a hand-held maneuvering unit powered by nitrogen gas. This effort was short-lived as he quickly ran out of the gaseous propellant. Finally, Collins reentered the Gemini 10 and with some effort was able to secure his hatch.
After 43 orbits, Gemini 10 reentered the Earth’s atmosphere on Thursday, 21 July 1966. The spacecraft landed at 21:07:05 UTC in the Atlantic Ocean, only 3 nm off target. Crew and spacecraft were recovered by the USS Guadalcanal.
Though highly successful, Gemini 10, like all Gemini missions, had its share of problems. But, just like all other Gemini missions, it was in the overcoming of its problems that Gemini 10 moved the United States materially closer to the realization of the nation’s lunar landing goal. While trying times lay ahead for the United States space effort, including a national tragedy, that lofty goal would be realized in the summer of 1969.