Though severe effects of microgravity on cells (e.g.
lymphocytes) have been stated, the development of complex
organisms occurs more or less undisturbed under this condition.
However, a systematic approach and multi-generation experiments
with animals and plants in microgravity are necessary as they
are the key players in life support systems which are necessary
for long-term manned space missions. In addition to rather
exclusive experiments under real microgravity conditions,
different ground-based methods have been developed to achieve
either the status of simulated microgravity (this term has been
adopted by international convention) or hypergravity (artificial
gravity) conditions. The DLR Institute of Aerospace Medicine has
a long-term experience in developing and using space simulation
facilities: so-called clinostats enable the rotation of a sample
perpendicular to the gravitational field assuming that a
continuously reoriented biological system does not perceive the
gravitational stimulus. The results