Experimental observations of adaptation processes of the motor control system to altered gravity conditions can provide useful elements to the investigations on the mechanisms underlying motor control of human subject. The microgravity environment obtained on orbital flights represents a unique experimental condition for the monitoring of motor adaptation. The research in motor control exploits the changes caused by microgravity on the overall sensorimotor process, due to the impairment of the sensory systems whose function depends upon the presence of the gravity vector. Motor control in microgravity has been investigated during parabolic flights and short-term space missions, in particular for analysis of movement-posture co-ordination. Analysis of long-term adaptation would also be very interesting, calling for long-term body motion observations during the process of complete motor adaptation to the weightlessness environment. ELITE S2 is an innovative facility for quantitative human movement analysis in weightless conditions onboard the International Space Station. This development is as a part of the Italian program for the exploitation of the International Space Station (ISS). Copyright �� 2003 by the International Astronautical Federation. All rights reserved.