This spacecraft, the first of a series of spacecraft used to investigate the means for manned space flight, contained scientific instruments, a television system, and a self-sustaining biological cabin with a dummy of a man. The spacecraft was designed to study the operation of the life support system and the stresses of flight. The spacecraft radioed both extensive telemetry and prerecorded voice communications. After four days of flight, the reentry cabin was separated from its service module and retrorockets were fired, but because of an incorrect attitude the spacecraft did not reenter the atmosphere.