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Hawking Center Information & Resources
Microgravity Information
What are gravity and microgravity?
Gravity is a force that governs motion throughout the universe. It holds us to the ground, keeps the Moon in orbit around the Earth, and keeps Earth in orbit around the Sun.
First described by Sir Isaac Newton more than 300 years ago, gravity is the attraction between any two masses. It is most obvious when one of the masses is very large, like Earth. The acceleration of an object toward the ground (near Earth’s surface) caused by gravity alone is called normal gravity, or 1g. This acceleration is equal to 32.2 ft/sec2 (9.8m/sec2).
As an example, if you drop an apple on Earth, it falls at 1g. If an astronaut on the Space Station drops an apple, it falls too; it just doesn’t look like it’s falling. That’s because the apple, the astronaut and the space station are all falling together. But they’re not falling toward Earth, they’re falling around it at the same rate. Since they’re all falling at the same rate, objects inside of the Station appear to float in a state we call zero gravity (0g), or more accurately, microgravity (1x10-6 g.)
More generally described by Hawking Center Fellow Niki Eggert to her first grade students:
Gravity is a force that pulls down on you when you are on Earth. It causes things to fall down to the ground and not float away. Micro is a word that means very, very small. In space, there is a tiny bit of gravity. So we call this microgravity. Although it looks like things float in space, they are actually falling at a much slower rate because there is microgravity.
How does ZERO - G achieve microgravity?
Using the same methods that NASA has used for over 45 years to train astronauts, Zero Gravity Corporation (ZERO-G) achieves microgravity through Parabolic Flight.
Parabolic Flight, sometimes referred to as weightless flight, is achieved using ZERO-G’s Boeing 727 aircraft named G-FORCE ONE. Weightlessness occurs by flying G-FORCE ONE through a parabolic flight maneuver. Specially trained pilots fly these maneuvers between approximately 24,000 and 34,000 feet altitude. Each parabola takes 10 miles of airspace to perform and lasts about one minute from start to finish.
The plane is initially pulled up to approximately 45 degrees ’nose high’ and then ’pushed over’ the top to reach the zero-gravity segment of the parabolas. For the next 25 - 30 seconds everything in the plane is weightless. At approximately 30 degrees ’nose low’ a gentle pull-out is started which allows the Flyers to stabilize on the aircraft floor. Finally, the g-force is increased smoothly to about 1.8 g’s until the aircraft reaches a flight altitude of 24,000 feet. The maneuver is then repeated.
The weightlessness experienced by everyone inside the airplane is actually equivalent to the type of "free fall" you experience when sky diving. In this case however, the body of the aircraft surrounds you and protects you from the on-rushing wind. At the end of the free fall period, the aircraft scoops you up and carries you back to the top of the arc to begin the free fall process again.
In addition to achieving zero-g or weightlessness, G-FORCE ONE can also fly a parabola designed to offer Lunar (1/6th) or Martian (1/3rd) gravity. These reduced gravity environments are also created with a modified parabola that is not quite as steep as zero gravity parabolas.
Hawking Center Fellow Chace Johnson explains the Zero Gravity flights in scientific terms to his high school students in the following fashion:
Based on Isaac Newton’s proposed gravitational formula, the force of gravity (Fg) = (G)(m2m2)/d2. Being that (G) is a gravitational constant, the only factors that can affect gravity are mass and distance. In parabolic flight, flyers’ masses do not change and their change in distance from the center of the Earth is negligible. Therefore, their gravitational force (Fg) is neither gone ("zero G") nor diminished considerably ("microgravity"). The average person is only aware of gravity due to an opposing force on his/her body (normal force) or by observing the direction an object falls in comparison with its surroundings (frame of reference). In parabolic flight, flyers become "contained projectiles" where their normal force is removed while their frame of reference stays the same (unless we have drift). Therefore, the illusion of zero-gravity is created.
Could you describe a typical education flight and what it feels like?
Prior to flying aboard G-Force One on an education mission, teachers must complete a professional development workshop with one of our specially trained Hawking Center Educator Fellows. During the workshop, participants learn about Force & Motion; Martian, Lunar and Microgravity concepts/applications; experimental design for G-Force One; classroom applications and experiments; as well as necessary safety precautions for performing experiments in reduced gravity.
ZERO-G recommends at least three weeks but no more than two months between the professional development workshop and the flight day. This time period allows teachers to fully engage students in finalizing experimental design, applying the concepts in the classroom and predicting outcomes for their ZERO-G mission.
On flight day, participating teachers meet with their Hawking Center Educator Fellows who will also be their Team Coach, to finalize experiments and plan the sequence of experiments, or experiment profile, according to the flight profile. They review needed equipment, video recording procedures and anticipated outcomes one more time.
The education flight begins like any other commercial flight. You taxi out to the runway and await permission to take off. Once granted, the captain flies out to the airspace designated by the FAA as ours for the day. About the time the captain of a commercial flight would be turning off the seatbelt sign, you are given the okay to unbuckle your seatbelt and truly “move about the cabin”. Your Team Coach leads you to the floating/experiment area and guides you through set up of your experimental equipment. As instructed by your coach, you will then lay on the padded floor to prepare for the first set of parabolas.
After a few moments of feeling pressed gently into the floor as you experience 1.8 g’s, the Flight Director will call out “Martian 1” and you begin to feel lighter. So light in fact that you may be doing one-finger push-ups with a smile on your face! Two Lunar parabolas follow.
Depending on your experiment profile, the Martian and Lunar parabolas are ideal for human feats. This period also permits teachers an initial opportunity to understand physical movement in reduced gravity environments.
After the first set of parabolas, you experience a one to five minute period of “Straight and Level.” During this time, you and your Team Coach quickly review the experiments you’ve planned for the upcoming parabolas.
The Flight Director then calls “ZERO - 1” and you begin to float right off the floor. It’s like nothing on Earth. Working with your coach and teammates, you perform the experiments as planned making sure to capture the data either through use of the two fixed cameras in each floating section or the assistance of the videographer and/or photographer on board.
Achieving weightlessness is an experience few teachers have tried. Those who have, say it is life-changing and the boost their students need to cement an interest in science, technology, engineering and math education.
A feeling of true freedom and a place where the impossible becomes real, parabolic flight is the only way to create sustained weightlessness without going into space.
What is a typical flight profile?
Flight profiles may vary, however most flights consist of 5 sets of three parabolas each divided by periods of “Straight and Level.”
For more information about experiments in microgravity or in the middle grades classroom, download a copy of “Over The Top: ZERO-G’s Guide for National Educators” by Deb Houts, Hawking Center Educator Fellow.
Can I experience weightlessness on Earth without flying in an aircraft?
No. Parabolic flight is the only way to experience true, sustained weightlessness (up to 30 seconds at a time) without going into space.
How can I get a ticket to weightlessness?
For more information on how you can fly aboard G-Force One, click on the link for your “Opportunities to Go Weightless”.
Other Online Resources
The main Zero Gravity Corporation web site - http://www.GoZeroG.com
The Official Stephen Hawking web site - http://www.hawking.org.uk
Space Florida web site - http://www.SpaceFlorida.gov
NASA Education - http://education.nasa.gov