Want to stay on top of all the space news? Follow @universetoday on TwitterMicrogravity is a synonym for free fall or zero gravity. In most cases it is a term that more accurately describes the phenomenon of weightlessness in space. When someone hears the term zero gravity they think of astronauts floating in space. However this does not completely describe what is happening. The fact is that even when an astronaut in Earth orbit is floating weightlessly he or she is not really free of gravity. The most obvious evidence is that the space craft or space station that they are in is still orbiting Earth due to the influence of its gravity. As a matter of fact Earth’s gravity field extends several hundreds of km from the surface. So in truth they are experiencing a reduced form of gravity or microgravity.
Microgravity occurs when there are no outside forces other than gravity acting on a body. This means that there are no forces acting on your body that are making you actively aware of the force of gravity. The reason you can say you are experiencing gravity on Earth is because of the different forces around you that are acting on you. For example you feel the ground beneath because of the equal and opposite normal force the ground is exerting on you in response to the force of gravity. In space this doesn’t happen. Free fall or microgravity happens as the spacecraft’s acceleration matches that of gravity causing weightlessness.
The weightlessness provided by this unique occurrence has become highly sought after by scientist and companies looking to perform experiments and manufacturing process that are only made possible in this environment. However the main agencies currently able to work in these environments are government run space agencies. However there are private companies that are developing commercial alternatives for the near future.
A major problem with microgravity is the effect it has long term on the human body. Over time weightlessness can weaken the body’s muscular and skeletal systems. This is because our bodies are designed to work under the strain of gravity causing the skeleton and muscles to respond in specific ways. Without with resistance bones become brittle and certain muscles can atrophy. Major research is going into resolving these issues as they serve a major barrier to long term human space flight.
We’ve also recorded an entire episode of Astronomy Cast all about Gravity. Listen here, Episode 102: Gravity.