[3] The spacecraft was based on the Zenit spy satellite with emphasis on studying the problems of radiation effects on human beings.

Scientists from Czechoslovakia, Romania and Soviet Union subjected the rats to daily radiation doses from a gamma source by ground command.

When they were recovered 21 days later, many rats had developed lung problems and their blood and bone marrow had changed more than those of control specimens.

Outwardly, ball valves with compressed nitrogen are attached to the gas nozzles of the stabilizer system.

The return module, weighing 3,100 kg (6,800 lb) and 2.3 m (7 ft 7 in) in diameter, was covered with an ablative thermal shield 3 to 18 cm thick.