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AN ANTIGRAVITY CHAMBER
1997 William J. Beaty

Here's a quick way to generate some completely genuine "zero gravity," same as on the Space Station. Actually, this is just a way to create freefall weightlessness. "Zero-G" means zero acceleration or no G-force, not "zero gravity."

The space shuttle orbits at about 300 miles above the earth. Did you know that, at 300 miles altitude, the gravity is only about 15% less than gravity at the surface? Gravity inside the space shuttle is 85% normal. It only appears to be zero. This happens because the space shuttle is falling, and the astronauts are falling as well. Whenever any container is falling free, the contents of the container will appear to be weightless. Of course the shuttle and its contents are also moving sideways as they fall, so they never hit the earth.

Our "zero gravity" generator is simply a TV camera in a well-lit box. By shifting our point of view to the inside of a movable box, we can create genuine "weightlessness", exactly the same as within any orbiting space craft.


FIRST CRUDE VIDEO TEST: FLOATING OBJECTS

MATERIALS:

  • Camcorder or small TV camera (or mpeg cam)
  • Television monitor
  • Long narrow cardboard box
  • Light fixture and floodlight
  • wooden boards

TOP VIEW:


       _____  spotlight
      |  ___|/|          _________________________________
      | <___  |          .                                |
  ____|_____|\|_____________________                      |
 |    ______             .          |                     |      TOP
 |   |      |__-         .          |                     |      VIEW
 |   |      |__          .          |                     |
 |   |______|  -         .          |                     |
 |__________________________________|                     |
   TV camera on a board  .                                |
                         _________________________________|
                                    Cardboard Box

CONSTRUCTION

Cut the cardboard box so that one side is missing, which gives a good view into the long narrow box. Attach the board to the side of the box, and attach the camera to the board. The camera lens should face into the box. (For convienence, build this with duct tape at first, use screws and bolts later on.) Affix a small flood light adjacent to the camera, and aim it into the box so that the camera has enough light to "see."

Connect power to the camera and flood light, and connect the camera to the TV or video monitor so that your audience can see into the box. Adjust the camera's zoom and focus to give the proper view of the interior (you may have to use the camera's "macro" mode.) For best depth of focus, make sure the interior of the box is brightly lit, then adjust the camera's f-stop for a high number.

OPERATION

Place some objects inside the box. I just grabbed a spool of tape, some magic marker caps, and a bottle of white-out, and dropped them in there. Watch the image on the TV screen, and carefully rotate the entire box assembly until it is upside-down. Your audience will probably break out in laughter, because the image of the box on the TV monitor will remain still, but the objects in the box will crawl up the wall and roll around on the ceiling! Violently shake the box, and the objects will seem to be flung about invisible forces.

To generate free-fall, suddenly lift/jerk the box so that the objects are launched off the "floor" of the box, then try to move the box to follow the objects so they momentarily stay centered in the middle of the box. Don't let the box go, or you might damage your camera! Your audience will see genuine ( and very brief ) free fall effects. The objects will leap into the air, then will drift around spinning, then will suddenly fall hard onto the floor.


IMPROVED VERSION WITH ONBOARD FLOODLIGHT



FANCY VERSION

If you have some ambition, you might wish to decorate the inside of your box. Paint it and add extra shapes to convert it into the inside of a space station. Add some small human figures (Barbie, etc.) dressed appropriately. Or, maybe decorate the interior so it looks like the padded cylindrical interior of NASA's "vomit comet" free-fall airplane. Dress your action figures in orange jumpsuits, and provide some air-sickness bags for the Senator!

If you have a sick sense of humor, build the inside of a commercial airliner into your box. Add passengers and steward/stewardesses, luggage racks, etc., then simulate what would happen if the 747 pilots decided to do loop-the-loops! Fear of flying? Or, you can fill your box with doll-house furniture, then show what a moving van looks like as it bounces and rolls down a steep hill. An "adventure in moving!"

This box/camera device duplicates the workings of NASA's free-fall simulator plane. Rather than climbing into a full sized aircraft, we use the video camera to shrink ourselves down and take a Virtual Reality ride inside the box. To generate free fall, the NASA plane flys in a parabola-shaped trajectory. Why? Well, imagine what would happen if the crew was inside of a box which was shot out of a huge cannon. Both the people and the box would fly along similar paths. The box would take a long, curved, up and down path, and so would the people inside. The people inside could not see the box move, so they couldn't know they were falling, instead would think that they were weightless (at least until the box struck the ground.) So, if an airplane flys in exactly the same path as a fired cannonball, everyone in the plane will seem to be floating. NASA free-fall aircraft: http://www.nasa.gov/missions/research/kc135.html

SIMPLE NON-VIDEO VERSION

If you obtain a small box, a shoe box or large cereal box, open up one end, and stick your face in, you will have the "poor man's version" of the video camera box. Stick some small toys or coins into the box. To generate momentary free fall, simply jump up and down. The objects inside the box will float for a moment. ( Be aware that jumping up and down with a box on your face looks really stupid. This demo is a great excuse to convince OTHER people to jump around with boxes on their faces, while you stand back and watch the fun!)

WARNING

Of course, always try to protect your camera. If you never let the box out of your control, then you'll only have yourself to blame for any mishap. Perhaps it would be wise to attach a hook to the ceiling, and attach the camera box to a rope to prevent accidental contact with the floor. A suggestion: use the tiny $80 video cameras sold by Herbach and Rademan, or by Marlin P. Jones. These things are a couple inches square, and can take lots more punishment than a camcorder. And if you drop it and break it, it was an $80 camera, not a $1200 camcorder.



 

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REFERENCES

NASA student competition: "Drop Tower:
http://microgravity.grc.nasa.gov/DIME.html

NASA Free-fall Activities
http://microgravity.grc.nasa.gov/new/frame4.html

NASA Free-fall Education Page
http://microgravity.grc.nasa.gov/new/frame1.html

NASA Drop-tower Demonstrator
http://microgravity.grc.nasa.gov/mini/minit.htm

NASA ask a Scientist
http://microgravity.grc.nasa.gov/new/frame12.html

NASA Microgravity Science Division
http://microgravity.grc.nasa.gov/

Gravity Misconception: Gravity in space is NOT zero




http://amasci.com/amateur/gravcam.html
Created and maintained by Bill Beaty. Mail me at: .