Simulation of Microgravity for Studies in Gravitational Biology: Principles, Devices and Applications

Scientists and technicians have been innovative to develop experimental platforms in order to achieve functional weightless conditions in their Earth-bound laboratories. As a result, various experimental platforms are available in order to perform studies with molecules or single cells up to humans and to study gravity-related mechanisms. These ground-based simulators of microgravity are not only tools to prepare spaceflight experiments, but they have been established as stand-alone facilities for gravitational research. This review provides an overview of some of the most frequently used microgravity simulators, most of which are in use at DLR´s Institute of Aerospace Medicine at Cologne, Germany. Their individual capacities but also experimental limitations, especially regarding their range of applicability for biological specimens, are exemplarily reviewed here. Overall, it is necessary to compare data achieved by using simulators with the data obtained in real microgravity. Furthermore, it should be carefully considered which kind of simulation might be the optimum for a given model organism or cell.