A capsule is a sealed, pressurized cabin that contains a controlled environment for humans, animals, or equipment during high-altitude flight or spaceflight. Capsules have been used on dozens of historically important missions from the earliest days of the U.S. and Soviet space programs.

The first space capsule orbited was the Soviet Sputnik 2. Launched November 3, 1957, it was only the second human-made object to orbit Earth. The capsule weighed 114 kilograms (250 pounds) and carried the dog Laika into space, but it was not designed to be recovered. Laika died in orbit four days later. Most capsules, however, are re-entry vehicles made to bring their occupants back safely to Earth.

Human-Piloted Capsules

The earliest human-piloted capsules were the Soviet Vostok and U.S. Mercury spacecraft. Vostok had a spherical compartment 2.5 meters (98 inches) in diameter with room for a single cosmonaut. It was attached to a coneshaped equipment module that carried supplies...