Cosmos 2229 was the eighth consecutive mission in the series of joint U.S./USSR experiments. Cosmos 2229 was an international venture, accommodating experiments conducted by scientists from Russia, the U.S., Germany, France, Canada, China, the Netherlands, Lithuania, Ukraine, Uzbekistan, and the European Space Agency (ESA). One of the main objectives of the mission was to conduct experiments within ESA's Biobox facility, a fully automated programmable incubator for research in gravitatonal biology. Several experiments were also conducted outside the Biobox facility. The biosatellite carried two rhesus monkeys, as well as several simpler organisms as experimental subjects. Thirteen of the life sciences experiments that used the monkeys as experimental subjects were sponsored by the NASA Ames Research Center. The experiments were designed to study various biological systems likely to be affected by the space environment. Bone and muscle are used by terrestrial organisms to maintain their body positions relative to gravity. The near absence of gravity during spaceflight has been found to cause significant changes in these body components in both monkeys and humans. To gather further data in this area, Cosmos 2229 experiments studied bone strength, density, and structure, bone biochemistry, calcium metabolism and neuromuscular function. Experiments on previous Cosmos and several Spacelab missions have also indicated that the neurovestibular system is affected by microgravity. Since the ability to perform coordinated movements is crucially important for astronaut crews, neurovestibular studies in space are a high priority. Three of the investigations on Cosmos 2229 were in this area. Immune and metabolic changes were also studied, as well as the way that circadian rhythms of brain, skin and body temperature respond to spaceflight.