The United States Biosatellite Program includes critical and sophisticated experiments to study the effects of weightlessness and decreased gravity at the cellular, tissue, organ, and organism levels during orbital periods of 3 to 30 days. The experiments involve a wide variety of plants and animals from single-celled organisms to primates. The effects of weightlessness combined with a known source of radiation will be studied to determine if there are any antagonistic or synergistic genetic or somatic effects on various organisms. Experiments are included to study the effect of removal from the Earth's rotation in relation to biological rhythms of organisms. The experimental test organisms have been exposed to the simulated dynamic forces of launch and flight profiles.