What are the effects of zero gravity on humans?
Many people believe that there is ‘no gravity’ or ‘zero gravity’ in space. In fact, a slight amount of gravity can be found everywhere in space. The correct terminology is not ‘zero gravity’ but ‘micro gravity’, which is a sensation of weightlessness when the effect of gravity is not felt.

Human body is adapted to the Earth’s gravity and hence it relies on it to develop properly. So living for long periods of time in space in a micro gravity situation can hamper an astronaut’s health in many ways. Let’s discuss a few.

During space flight, the bone density decreases by 1-2 percent per month leading to conditions similar to Osteoporosis where the bone loses minerals (especially Calcium) leading to weaker, more brittle bone susceptible to fractures. The process of repairing and replacing of damaged and old bone is also affected, leading to further net bone loss.

Muscle mass in space is also lost as the body doesn’t require muscle for support. The astronauts’ exercise for two hours everyday in order to maintain the body mass they could require once back on Earth.
Astronauts at International Space Station exercise daily to maintain body mass
Additionally, the heart of the Astronaut become more spherical and loses muscle mass. Within a few days of weightlessness, astronauts can lose as much as 22 percent of their blood volume. This change affects the heart as less blood is being pumped by the heart leading to Atrophy.

These are only a few effects on the human body during microgravity.Various studies are being carried out to study physiological and psychological changes in human beings. But the question is, do such changes matter?

Perhaps not if you plan to stay in space forever, but astronauts in fact return to Earth and the human body has to readjust to the relentless pull of gravity. Most space transformation appear to be reversible, but the rebuilding process is not necessarily an easy one.
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