The early U.S manned spaceflight program
The six Project Mercury manned missions were flown between May 1961 and May 1963. The one-astronaut crews were instructive in tolerance of liftoff stress, work in zero-gravity and pressurized spacesuits. It carried enough food, water and oxygen for about one day. Flight was controlled from the ground, with back-up astronaut controls. A heat shield protected the bottom of the capsule during reentry into the Earth’s atmosphere. Parachutes deployed at about 10,000 feet and the capsule landed in the ocean, with an inflated flotation collar. Recovery was made by helicopters and crew from Navy ships.
The 10 Project Gemini manned missions were flown between March 1965 and November 1966. The two-astronaut crews established abilities to endure longer space flights (including an 8-day and a 14-day mission); to perform extravehicular activities (or spacewalks); and pilot rendezvous and docking activities with other space vehicles. Those activities were crucial for the development of a lunar landing capability. The Gemini craft did not have an escape tower, but had ejection seats similar to those in fighter jets (though they were never used in launches).
The Apollo program’s manned missions were flown between October 1968 and December 1972. Two crews of three astronauts made Earth orbit-only missions — Apollos 7 and 9. Three made moon orbits and returned — Apollos 8, 10 and 13 (which had an explosion in the service module that cancelled a planned landing). Six made lunar landings — Apollos 11, 12, 14, 15, 16 and 17. More than 840 pounds of lunar rock was returned, some gauged to be 4.6 million years old. The program’s dominant use of integrated circuits, spurred many advancements in that field.