Conceived as the first Soviet space probe, Object D was bumped by the less ambitious Sputnik in a bid to beat the Americans. It worked. They won. Object D finally flew as Sputnik 3 on May 15, 1958.
The Object D was conceived as a multi-functional science laboratory with an ambitious array of instruments onboard. It was expected to measure the density and ion composition of the Earth’s atmosphere and its magnetic field, and to study solar radiation and cosmic rays. The first satellite also promised a wealth of engineering data, which could later help in the development of attitude- and thermal control systems for future spacecraft, as well as information on the interaction of satellites with the upper atmosphere.