|MadSci Network: Engineering|
Very good question Thomas. If you have unlimited freedom of movement, it's quite possible to orient yourself in microgravity without touching anything. During one of the Skylab missions, Dr. Owen K. Gariott made a demonstration film showing how you can orient your body by moving your arms and legs in various directions and patterns. An easy way to do a somersault, for example, is to rotate your arms about your shoulders opposite the direction you wish to somersault. If you're facing one way and wish to turn 90 degrees to the left, you extend your straightened legs out to each side and then "turn" on your legs, by now moving them so your left leg is extended forward and your right leg is extended behind you. It's a wonderful demonstration of conservation of angular momentum. However, when wearing a spacesuit--especially with a jetpack--your freedom of movement is very limited. Besides the bulkiness of the suit itself, you also have to contend with its stiffness due to the ballooning effect of it being pressurized. While engineers do the best they can to maximize freedom of movement in a spacesuit, it is still a very cumbersome and, indeed, tiring garment to wear. Motions like I describe above are very difficult if not impossible to perform. But even if this wasn't the case, it's much safer and much more efficient to have a jetpack provide full control of your movement and rotation in all directions and all axes. This is epsecially true in emergency situations. If you suddenly realized you were about to hit something, it wouldn't be very safe to have to first rotate your body away from what you were about to hit (where you coudn't see it) and then thrust with the one jet mounted on your back. It's much better to keep the object in sight and thrust sideways or otherwise correct your trajectory with one of your 24 vernier jets. Hope that gives you some understanding, -Adams Douglas
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