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Question ID:   2195         Current Version: 1

Question:	How to create microgravity?
Category:	Science > Astronomy & Space
Keywords:	create, simulate, condition, environment, mocrogravity, gravity
Type:	how

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Answer:

The condition of microgravity comes about whenever an object is in "free fall": that is, it falls faster and faster, accelerating with exactly the acceleration due to gravity (1g). As soon as you drop something (like an apple) it is in a state of "free fall". The same is true if you throw something: it immediately starts falling towards the Earth. But how does something fall around the Earth? Newton developed a "thought experiment" to demonstrate this concept. Imagine placing a cannon at the top of a very tall mountain. Once fired, a cannonball falls to the Earth. The greater the speed, the farther it will travel before landing. If fired with the proper speed, the cannonball would achieve a state of continuous free-fall which we call orbit. The same principle applies to the Space Shuttle or Space Station. While objects inside them appear to be floating and motionless, they are actually traveling at the same orbital speed as their spacecraft: 17,500 miles per hour (28,000 km per hour)! Objects in a state of free-fall or orbit are said to be "weightless." The object's mass is the same, but it would register "0" on a scale. Weight varies depending on if you are on the Earth, the Moon, or in orbit. But your mass stays the same, unless you go on a diet! NASA uses a variety of facilities to create microgravity conditions. The most "famous" way is by aircraft flying in parabolic arcs to create microgravity for tests and simulations that last 20-25 seconds. NASA's Johnson Space Center, for example, operates a C-9 Low-G Flight Research aircraft also known as the "Vomit Comet." It make several trips each year to NASA Glenn in support of ground-based microgravity research. It's predecessor, a KC-135 aircraft, was used to shoot the weightless scenes in the movie "Apollo 13." The facilities most-likely to be misconstrued as "anti-gravity chambers," are NASA's drop towers. Specifically, NASA Glenn has the "Zero Gravity Research Facility." It is a large shaft some 500 feet deep that allows test packages to free fall in a vacuum for just over 5 seconds. In this state of free fall, weightlessness (at or near microgravity) can be obtained. NASA Glenn also has a 2.2 second drop tower. You may have experienced weightlessness yourself and not realized. Many amusement park rides create brief periods of free fall. Some rides that operate vertically without any applied forces are actually classified as "free fall rides." Most roller coasters have a set of parabolic (rolling) hills that also create brief periods of weightlessness. For less adventurous people, a car ride on the rolling hills of a country road or jumping on a trampoline also create brief experiences of weightlessness.

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