A spine floats free. In microgravity, the axial loading that normally squeezes its vertebrae fades, allowing intervertebral discs to absorb fluid and widen while the vertebral column's natural curves ease. Bones do not lengthen. You are seeing decompression, not growth, and the change can make an astronaut temporarily taller. Standing is gone. So is the daily impact of each step.The extra height i...More