Gravity spectrum currently explored in motor control and human neurophysiology. Gravity is represented on the horizontal axis. Centrifuges can be used to explore the red zone above the axis and parabolic flights can be used to explore the blue zone. The special conditions at +1 g and −1 g can be tested on the ground. Interestingly, the interval 1–1.8g can be studied both in centrifuges and parabolic flights. Below the axis, the rectangle quantifies the knowledge we have about motor control across gravitational environment (see key for the rectangles).