Long-duration spaceflight causes a significant physical shift of the human brain within the skull, moving it backward, upward, and rotating it in pitch. By analyzing MRI scans of 26 astronauts, researchers found that these displacements—reaching over 2 millimeters in long-duration flyers—are widespread across nearly 130 brain regions and correlate with post-flight balance issues, particularly when shifts occur in sensory-related areas. While most of these anatomical changes recover within six months of returning to Earth, some deformations persist, suggesting that current ground-based microgravity simulations (like head-down tilt bed rest) do not fully capture the complexities of how actual space travel alters neuroanatomy. Despite these detailed findings, the most pivotal unanswered question remains: what are the long-term clinical and cognitive consequences of these physical brain shifts, and do they pose a permanent risk to the health and longevity of astronauts embarking on multi-year missions to Mars?

This video provides an overview of how the brain physically repositions itself during spaceflight and the potential implications for future missions to the Moon and Mars. [1]

[1] https://www.youtube.com/watch?v=90EQEor52hs