"Bion" is a series of Soviet (later Russian) space vehicles (SV) meant for biological investigations.

The development of specialized "Bion" SV began in the early 70s in the Kuybyshev branch of the OKB-1 (Development Design Office) which is Samara TsSKB "Progress" in our days. The OKB designers worked in close contact with specialists of the Moscow Institute of Biomedical Problems because not just a regular satellite was being developed, but a series of SV meant for biological experiments. The construction of the biosatellite got a corporate name 12 KC and repeated to a large extent the construction of the photointelligence SV "Zenit 2M" developed earlier. The differential characteristic of "Bion" satellites is the fact that they conduct a flight in a free regime after they are inserted into the orbit, without orientation systems. Due to this fact the perturbations are minimized, and the level of micro-accelerations remains low during the whole flight. This allows performing such "refined" researches and experiments where very strong requirements to creation of "pure" weightlessness are applied.

Automated space vehicle "Bion" is the only specialized space complex in the world where the performance of the biological experiments with the use of rodents as bioobjects is possible that allows solving some practical problems actual for studying of systematic body responses (skeleton, muscles, cardiovascular system, nervous system) to microgravity and artificial gravity effects, and also to cooperative effect of radiation and microgravity. Analog experiments with rodents at manned space vehicles are impossible because of sanitary standards.

The leading role in forming and realization of the program of "Bion" and "Bion-M" flights belongs to the State Scientific Center of the Russian Federation – Institute of Biomedical Problems of the Russian Academy of Sciences.

Photo from the site of Roscosmos. Assembling of the "Bion-M" No. 1 SV.