The mission differed markedly from earlier Cosmos flights, both in terms of Soviet scientific goals and in the degree of cooperation required between the U.S. and the U.S.S.R. The two countries had to interact at a high level because much of the U.S. experiment hardware had to be integrated with the Soviet spacecraft and instrumentation systems. Experiments focused on the effect of weightlessness on various physiological parameters. A study of circadian rhythms was concerned with the synchronization of primate motor activity, body temperature and skin temperature rhythms to a fixed light/dark cycle and to each other. Blood pressure and flow were monitored, to evaluate short and long-term changes in these parameters. Changes in calcium metabolism were studied in order to determine the effect of weightlessness on the skeleton. The two rhesus monkeys (Macaca mulatta) flown onboard were about three years of age and each weighed approximately 4 kilograms. Height was a constraint in selecting animals for flight. This was because a Soviet vestibular experiment required that the flight restraint couches oscillate vertically within the animal capsules. The monkeys were conditioned to sit in the restraint couches and perform tasks for food rewards. Tasks included pressing a lever with their feet and tracking a moving light with their eyes. Monkeys were also trained to eat and drink from food and juice dispensers. Monkeys in the flight and control groups were implanted with blood pressure and flow cuffs and sensors to measure several physiological parameters. A neuroontogeny experiment was conducted to investigate space flight effects on the sensory development of rats that spent part of their prenatal gestation period in space. Ten pregnant female Wistar rats (Rattus norvegicus) were flown. Ground control groups contained the same number of rats. At the start of the flight or control experiments, the rats were at gestation day 13 of their 21-day cycle.