The Economic Times

In 1987, Bion 8 carried monkeys Yerosha and Dryoma for 13 days; Yerosha escaped part of his restraints before the capsule landed 1,850 miles off target

The Soviet Bion program studied weightlessness effects using rhesus macaques. Bion 8 launched in 1987 with two monkeys, Yerosha and Dryoma. Despite hardware issues and a landing mishap, significant scientific data was collected. Experiments revealed nervous system adaptations to microgravity conditions. Lessons learned improved subsequent Bion missions and animal space research.