Cosmos 1645

The Foton satellites are built on the basis of the Zenit satellites, themselves derived from the Vostok spacecraft. Foton has a mass of 7t, can carry 625kg of equipment, and has an operational life in orbit of thirty days. A Bion satellite can be broken down into three parts: the Drop Compartment, the Descent Compartment (SA) and the Instrument Compartment. Only the SA Compartment is capable of returning to Earth. It contains most of the scientific payload. It is shaped like a sphere 2,3 m in diameter and has two hatches 1,2 m in diameter. The Instrument Compartment is cylindrical in shape and has a mass of 500kg. It has a diameter of 2m and a length of 50cm. It also contains scientific experiments.