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Movements in Space
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In space we encounter Zero Gravity, so basically weight doesn’t count. But how about other factors such as shape and mass. Do the shape of an object that travel in space has an effect over its movement? Does a wide & flat object has the same acceleration in space; compared to the "aerodynamic" design? I also had a question about propulsion. How fast is our current propulsion system, and how much does it take to travel to.. take Mars for example. I mean, will it take meters of space and volume in the space craft. And how does it really work? Today "propulsion" for satellite are using orbital trajectory, meaning that it uses the earth and other planets to us as an orbital anchor. After it gaining enough speed through orbital circulation, it speed up and break away in the direction of the targeted objects and thus space travel is achieved. But i don't think it's a true propulsion system. I mean it can't change course and it have to use the orbital/ circling the planet as an anchor. Feel free to critics.
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Re: Movements in Space
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Mmm.. I'll have a shot at explaining part of this... Firstly, be careful there. So many people think that "there is no gravity in space". In reality, the gravitational force has influnce from the source of the gravity to infinity. While people often say astronauts in orbit are weightless, this not technically correct. They are experiencing apparent weightlessness because they are in constant freefall, not because they lack weight. The force of gravity still acts upon them, but their "floor" falls away as fast as they fall toward it. Of course, since the force is an inverse square with respect to distance, it can get rather insignificant at great distance. That aside, there is little air in space. (Err.. understatement?) It's a vacuum. As a result, friction caused by turburlence or air resistence is non-existant. Hence aerodynamics doesn't come into play, ie: all other things equal, wide and flat vs bullet nose makes no difference. I'm not very knowledgable about propulsion systems, so I'll pass the buck to someone else who knows more, or perhaps you could look up the figures somewhere. Not really sure what you mean by "it take meters of space and volume in the space craft. And how does it really work?". If you refer to propulsion and propellant having mass and requiring storage... Then yes, they do. When designing craft (or most any engine really) the amount of propulsion (and it's efficiency) compared to the weight that is taken by the system must be taken into account. Clearly if your engine that supplies one Newton of thrust for every ten litres of fuel in a vacuum is going to have a mass of five kilograms, it's not going to push itself very far when you take into account the weight of fuel. And of course for it to be useful it has to pull along something with it which also has mass... However, I will point out that satellites being slingshotted around planets is a form of propulsion... (I'm assuming by sattellite you refer to unmanned probes in general.) Other than not being "live" I don't see how this differs from other methods of propulsion. Sure, with a rocket you can shut it off midflight, but in the vaccum of space once you've headed in a direction, you'll keep going in that direction (assuming negligible outside forces such as gravity, prescence of obstacles, etc) until you supply another force to change direction. Same goes for using "slingshot" orbits... Although we try to avoid it in practise, you can change your course by supplying thrust midflight. It's far more inefficient than figuring the trajectory correctly to begin with though. We use planets' gravitational fields to propel us because it is highly efficient. We don't have to carry fuel for it, we don't have to pay for it, we only need to make sure our calculations don't hurl our probe into a moon... The difference between using an orbit and burning an imperial crapload of fuel to accelerate our probe (and it's fuel) to the same speed is cost and effort. Of course, you'll still need some form of thrust to get these things into orbit in the first place so you can try and exploit gravitational fields for your benefit :p Hmm... I've rambled a bit on here. If anyone wants to correct me or make clarifications feel free... my physics is a little rusty and it's 1am here........ not really sure why I decided to post on a forum at 1am.... But hopefully that clears up a few things for you, lenn08. |
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Re: Movements in Space
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Sure do, you clear up a lot things about this. Thanks especially about the zero gravity explanation. But I'll appreciate anyone who would add any explanation about this.
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