A space capsule is an often manned spacecraft which has a simple shape for the main section, without any wings or other features to create lift during atmospheric reentry. Capsules have been used in most of the manned space programs to date, including the world's first Vostok and Mercury manned spacecrafts, as well as in later Soviet Voskhod, Soyuz, Zond/L1, L3, TKS, US Gemini, Apollo, Chinese Shenzhou and currently developing US, Russia, India manned spacecrafts. A capsule is the specified form for the Crew Exploration Vehicle.
A manned space capsule must have everything necessary for everyday life, including air, water and food. The space capsule must also protect astronauts from the cold and radiation of space. A capsule must be well insulated and have a system that controls the inside temperature and environment. It also must have a way that the astronauts won't be knocked around during launch or reentry. Additionally, since the inside will be weightless, there must be a way for the astronauts to stay in their seats and beds during the flight. For this each seat, bed, table, and chair has a complicated system of straps and buckles. One of the most important things that a space capsule must have is a way to communicate with people back on Earth, or mission control.