Do-it-yourself projects and technology updates

How to experience zero gravity

I have said before that I used to work for NASA in Houston, Tx at Johson Space Center. One of my jobs while there was to work at Ellington Field, which is where JSC keeps all of their airplanes. They have a wide variety of planes that are based there, including the Super Guppy (google it, you will be glad you did), and the T-38’s which are small jets that the astronauts fly about twice a month, to keep in practice.

Now one of the best and coolest planes they keep there is the KC-135, or the Vomit comet. Now have you ever watched the movie Apollo 13, and asked yourself, how did they make them look so real when they were floating? The answer is that they were really floating. They were riding in the “Weightless Wonder”. Now you see the above picture is of me, floating in the KC. I am going to tell you how this is done, and what it is for.

Now this is a picture of my flight crew in front of the KC. A KC-135 is just a military refueling plane that has been modified.

So how can you achieve weightlessness on Earth? To answer that, I have to explain something. I am sure you have always heard that people float in space because they are out of earth’s gravity. Lets think about that for a while. What causes our tides? Isn’t it the pull of the moon’s gravity? Why is the moon orbitting the earth? Isn’t it because of gravity? Now if there is gravity reaching as far out as the moon then how can we be “out of earth’s gravity” at a mere 250 miles above the earth’s surface? The answer is that you are not at all.

Lets say you are holding an apple in an elevator at the 100th floor. This elevator gives away, and you start to fall. After everything has settled, and you are falling at a constant rate, you will start floating in the elevator, and the apple will appear like it is floating too. You are all falling at the same rate, and it seems like you are weightless, that is until you hit the ground, and then your fun game will be over.

Now imagine if you could move the ground further away from you as you were falling. You could apparantly fall forever, and float. Sir Isaac Newton figured out that if you get on a mountain, and throw a rock, it will go farther then if you are on the ground and throw a rock. If you throw the rock faster, it will go further yet. Now the key is at a certain height above the earth, and a certain velocity, you could get a rock to be going so fast that as it is falling, it is also going around the curvature of the earth. This rock will always be falling towards the earth, but the curvature causes it to be like the floor is always being pulled away from it. The rock is in orbit. It appears like it is “out of earth’s gravity, but it is really just falling” If you slow the rock down, then it will fall back to earth. This is the same concept of people in a space shuttle, or on the space station.

Alright, so you and I can’t go 22,000 miles an hour very easily, so short of a fun elevator ride, how are we going to float on earth? There is another way. You could go to the ride “Freefall” at six flags, and get about .5 seconds of reduced gravity. If you put a penny on your knee, you can see it floating. But you are strapped in, and you don’t get over the stomach in your throat feeling before it is over. You could also go skydiving, and you would be freefalling, but you are feeling the affects of the wind, and it is not the same. There is one other answer.

Buy yourself a large aircraft, such as the KC-135. Gut out the fuselage, and put padding all around, so if you hit your head at the end of the ride, it won’t hurt as much. Here is a pic. of the inside of the plane.



Now what do you have to do with the plane to feel weightless? The answer is you fly the plane is a sin wave. here is a picture I got on
NASA’s website.

Now at the top of the sin wave, as the plane starts to nose over, the plane pushes everything inside to negative gravity. The centripetal (it may be centrifugal. I can’t remember) force pushes everything to the outside from the way the plane is curving. If the pilots keep the trajectory right, then you can feel about 30 seconds of weightlessness. Now the opposite is true at the bottom of the wave. You feel about 2 G’s worth of gravity. They do this about 40 times on a flight. That is why they call it the “Vomit Comet”.

Here is a video link of lunar gravity. If you don’t push the nose over as fast, you can simulate the gravity of the moon, which is about 1/6th that of ours. It is a lot of fun, and you can jump around a lot
KC-video

Also, here is a video with a cat in space. I thought it was funny.
[Cat in space]

This entry was posted on Wednesday, November 16th, 2005 at 10:31 am and is filed under DIY Projects. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.