Introduction to the Effects of Microgravity on the Human Body

What is microgravity?

The surface of earth has a 1G acceleration environment and all life on Earth has developed and evolved in this gravity field. We as humans were born in it, we live in it and most of us will die in it. However there are a few of us who have the chance to experience the microgravity environment.

Microgravity can be defined in different ways. “Micro” derives from the original Greek word “mikros”, meaning “small”, so we can consider any gravity field that has lower gravity than Earth to be microgravity. But micro can be also considered as 10 to the power of -6th to be microgravity based on how it’s used in mathematics. In this meaning, it is only true for low Earth orbit (LEO) and most weightless environments, but not to the Moon or Mars.

In a general sense however, we use microgravity for every situation where gravity is smaller than on Earth, and I will use it in this meaning too.

Difference Between Short and Long-Duration Missions

It is crucial to differentiate between short and long-duration missions, because the human body responds differently based on the time spent in microgravity, so the countermeasures are also different.