Introduction to Microgravity
WHY Microgravity Research?
One of the most promising new areas for the commercialization
of space is in the field of microgravity. Microgravity allows new
materials to be developed which can not be made on Earth due to
gravity. These new materials can be used to speed up future computers,
reduce pollution, improve fiber optics, and enable medical breakthroughs
to cure diseases.
WHAT is Microgravity?
Microgravity, also called weightlessness or zero gravity, is the
absence of gravity. It is best illustrated by astronauts floating
in their spacecraft. They are floating because they are in a microgravity
environment. Besides astronauts, many people experience microgravity
every day by riding roller coasters or jumping off diving boards.
It is the "free fall" period of these activities when
the microgravity occurs and of course only lasts for a short period
of time.
HOW is microgravity achieved?
For research, microgravity is obtained by five methods.
- Drop tower. The payload is simply dropped
off the top of the tower and allowed to fall. This can provide
2 seconds of microgravity at a cost of pennies per pound.
- Airplane flying parabolas. The semi-famous
example is the NASA Vomit Comet which is also used to train astronauts
to work in a microgravity environment. This method can provide
25 seconds of microgravity at a cost in the range of a few dollars
per pound.
- Sounding rocket. The rocket goes up and comes
down in the same general vicinity, never getting into orbit.
Today's sounding rockets can provide between 3 to 9 minutes of
microgravity at a cost of approximately $1,000,000 per launch
and payloads weighing around 1000 pounds (which equates to $1000
per pound).
- Space Shuttle or International Space Station. Days
of microgravity can be achieved. The cost for putting a payload
in orbit with the Space Shuttle is $10,000 per pound. Once available,
the estimated cost for having commercial payloads on the International
Space Station is $15,000 per pound (not counting the $10,000
per pound to get it there on a launch vehicle such as the Space
Shuttle or the Russian Soyuz rocket).
- Slowly spinning an object. This is not a true
microgravity environment but simulates microgravity in certain
processes. Those processes must have slow reaction times such
as many biological processes. The axis of rotation must be parallel
to the ground and only provides benefits in certain applications.
HOW does one gain access to microgravity?
Take a coin. Toss it in the air. You have just subjected that
coin to microgravity. From the time it leaves your hand until it
hits the ground (or any solid object) it is experiencing microgravity.
The time in microgravity might be 1 to 2 seconds depending on how
high you toss the coin. For extended periods of time, one of the
methods described above will be needed.
While the current costs of achieving extended periods of time microgravity
are high, another major hindrance to microgravity research is getting
flights. There is a substantial backlog for flights on the Vomit
Comet and Space Shuttle. Researchers can wait years to get a flight.
Flights on today's sounding rockets have over a 12 month lead time.
Additionally, the Space Commercialization Act passed by the Unites
States Congress in 1996 makes it ILLEGAL for NASA to fly commercial
payloads on the Space Shuttle or the Vomit Comet! Therefore, all
researchers must submit their experiments to NASA committees to
determine which experiments are "good science" and eligible for
a NASA flight.
A truly exciting development in the area of microgravity is a new
commercial microgravity company called Zero Gravity Corporation.
This company has begun offering people the chance to experience
25 seconds of microgravity via parabolic airplane flights. World
famous physicist Stephen Hawking recently experienced the freedom
of microgravity on one of these flights. www.GoZeroG.com has
more information on the company and Prof. Hawking's flight.
Images courtesy: NASA
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