The spacecraft orbited the Earth for 21 days until its biological capsule returned to Earth on 22 November 1973 in a region of northwestern Kazakhstan. It carried several dozen male rats (possibly 25 or 45 ), six Russian tortoises (Agrionemys horsfieldii) (each in a separate box), a mushroom bed, flour beetles (Tribolium confusum) in various stages of their life cycle, and living bacterial spores. It provided data on the reaction of mammal, reptile, insect, fungal, and bacterial forms to prolonged weightlessness.
