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Hazard: Gravity Fields

Floating weightlessly within a spacecraft can lead to dizziness, bone and muscle loss, vision issues, and more. Astronauts may also need time to adjust to new gravity fields after landing on the Moon or Mars before they conduct mission-critical tasks. Developing strategies that enable crew members to adapt quickly to different gravitational fields will be key to mission success.

Christina Koch microgravity.

Astronauts will encounter three different gravity fields on a Mars mission. On the six-month trek between the planets, crews will be weightless. While living and working on Mars, crews will be in approximately one-third of Earth’s gravity. Finally, upon returning home, crews will have to readapt to Earth’s gravity.

Switching from one gravity field to another is trickier than it sounds. The transition affects spatial orientation, head-eye and hand-eye coordination, balance, and locomotion, with some crew members experiencing space motion sickness.

Landing a spacecraft on Mars could be challenging as astronauts adjust to the gravity field of another celestial body. When shifting from weightlessness to gravity, astronauts may even experience lightheadedness and fainting.

Without the continuous load of Earth’s gravity, weight-bearing bones lose on average 1% to 1.5% of mineral density per month during spaceflight. Water and other fluids in the body shift upward to the head, which may put pressure on the eyes and cause vision problems. If preventive measures are not implemented, crews may experience an increased risk of developing kidney stones due to dehydration and increased excretion of calcium from their bones.

Learn more about how NASA studies the effects of gravity transitions on the human body:

Gravity Research and Training Platforms


Operated by the German Space Agency (DLR), this research facility allows NASA researchers to study how low gravity—simulated by continuous bed rest with the head tilted down— affects the eyes and the brain.

astronaut training in NBL

Neutral Buoyancy Laboratory

A 6.2-million-gallon pool at the NASA Johnson Space Center in Houston allows researchers and astronaut trainers to manipulate buoyancy to simulate partial gravity.

Evaluating the Advanced Crew Escape Suit


The Active Response Gravity Offload System (ARGOS) simulates different gravity fields by connecting astronauts to an overhead crane that senses their actions. The system then lifts, moves, and descends the astronauts as if they had performed their actions in partial gravity

The International Space Station orbiting above Earth. Four large pairs of solar panels are seen on either side of the station.

International Space Station

Research conducted on the space station helps NASA scientists better understand and manage the health effects of long-duration missions, including those related to microgravity.

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