Space Shuttle

This is a discussion on Space Shuttle within the A Brief History of Cprogramming.com forums, part of the Community Boards category; >>> I think they re-enter that fast so that they aren't overly exposed to the heat of the atmosphere, but ...

  1. #61
    It's full of stars adrianxw's Avatar
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    >>>
    I think they re-enter that fast so that they aren't overly exposed to the heat of the atmosphere, but i'm probably wrong.
    <<<

    It is the speed of re-entry that creates the friction that creates the heat.

    Basically, in space, the orbiter, (or whatever), can, (and have too), travel very fast simply to orbit. Think about it, if you throw a stone vertically up in the air, it falls down again - gravity. Now throw the same stone horizontally, it falls to the ground, but some distance away. Throw it harder, (i.e. give it more velocity), it lands even further away. Now, consider this, if you threw the stone fast enough the stone would start falling to the ground, but the Earth is round, so it falls and falls, but the Earth's surface is "falling away" at the same rate, hence the stone never hits the ground - it has orbital velocity. (In practice you couldn't do this at ground level because the speed needed to acheive orbit would generate so much heat, the stone would vapourise!).

    Next problem, the atmosphere. If you move something through the atmosphere, it pushes through the air. The air in front of the object has to rush around the object and take it's place behind the object, in doing so it creates friction, (more correctly called "drag" in aerodynamic terms), which creates heat. If you rub your hand accross a carpet for example, you feel your hand getting warm, rub it faster, you feel it get warmer.

    Now, you have a space craft at orbital velocity in space where there is little or no drag, but you want it on the ground at zero speed. You have very little fuel to slow yourself down, because fuel is heavy, so what you do instead, is slow yourself a little, i.e. to just under orbital velocity, and you begin to fall in a long arc to the ground. As you get deeper into the atmosphere the drag, and the friction, increase, hence the the heat, but you also shed velocity since the friction slows you down, it acts a a brake, indeed, this is technically known as "aerobraking".

    Now, as long as you can shield yourself from that heat, (which can be thousands of degrees), you get a free braking mechanism, a little fuel to keep the craft at the right angle, but otherwise, the atmosphere is doing all the work.

    What may have happened to Columbia, is that some of the ceramic tiles which shield the ship from this heat have been damaged or knocked off, and the heat has got at the ship itself, damaging or melting parts of it. If that happens to a critical component, it can break, and cause a catastrophic failure of the entire system, remember, although it does not have orbital velocity any more, it is still going REALLY fast. (A Concorde airliner flies at Mach 2, these guys were doing Mach 18 when it started to go wrong). Loose a bit of wing or similar at those speeds and the thing will simply tumble out of control and break up in a fraction of a second.

    I hope that makes sense. (To those who know more, yes, I know it is more complicated than that in practice, but that is essentially what is happening!).
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

  2. #62
    It's full of stars adrianxw's Avatar
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    TD:

    >>> I think wheyre not yet prepared to go into space.

    The problem with that kind of argument is that really, no one would ever get anywhere. If you sail a boat a few metres from the shore, and it doesn't sink, great - boats work! Sail the same boat out into the Ocean and it founders, okay, learn from that and build a better boat.

    Point, you develop boats for centuries that work a few metres from the shore, but they may still fail further out - you just have to try them.

    As for the newer technologies, have you seen any new technology capable of lifting a load, however small into orbit? They may come, but they're not available today.
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

  3. #63
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    And i quote that i said that far better means of transportation
    are now under development, Why continue on the brute fuel
    ignition method?

    Originally posted by Travis Dane
    I saw alot of new technology's developed far better than just
    ordinary gas fuel.

  4. #64
    It's full of stars adrianxw's Avatar
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    >>> Why continue on the brute fuel ignition method?

    ... and I quote...

    have you seen any new technology capable of lifting a load, however small into orbit?
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

  5. #65
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    Originally posted by adrianxw
    >>> Why continue on the brute fuel ignition method?

    ... and I quote...
    Not yet, But wheyre working on it hard, As i said, There are some
    promosing technology's out there. At the moment, No there isn't
    something capable of performing that task, But i don't find it
    worth risking human lives just to go a little earlier into space.

  6. #66
    Mayor of Awesometown Govtcheez's Avatar
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    Travis, you mind if I ask how old you are?

  7. #67
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    Originally posted by Govtcheez
    Travis, you mind if I ask how old you are?
    I feel something bad heading my way, 15.

  8. #68
    Mayor of Awesometown Govtcheez's Avatar
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    OK, that's about what I thought.

  9. #69
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    Originally posted by Govtcheez
    OK, that's about what I thought.
    Ok, Come on, Cough it up!

  10. #70
    Mayor of Awesometown Govtcheez's Avatar
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    Nothing - you just act your age.

  11. #71
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    Originally posted by Govtcheez
    Nothing - you just act your age.
    How about specifying why you think that? Am I too carefull?
    Should whe just put some guys on a rocket and shoot them into
    space? Well, Whatever....

  12. #72
    Funniest man in this seat minesweeper's Avatar
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    Talking of technology for propelling rockets, a while ago I saw a program that had a demo of a new technology. It was, from what I remember (it was a while back) a laser or something similar that was projected onto the surface of a piece of metal coated in a substance of some sorts. Anyway, the result was a localised pressure increase (small explosion) against the coated surface. The demo had the laser on for a fraction of a second and blasted the piece of metal high up into the sky. It was cool, even if a little difficult to control.

  13. #73
    It's full of stars adrianxw's Avatar
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    >>> Should whe just put some guys on a rocket and shoot them into space?

    Consider, if we had waited until a really safe launch technology existed, the first astronauts would have been suprised to find that their bones started deteriorating. We know that happens, because people have been in space and found it out. So now they go up knowing what to do about it.

    Your approach may be commendable in terms of safety, but it is the boat a few metres from shore approach.

    What alternative launch technologies are you thinking about anyway? I am well aware of the different types of engines being developed, (and cancelled willy-nilly by underfunding), and of different fuels being investigated. It is also possible that orbital velocities may be possible with SCRAM jets, (although I do not believe they are in any way safer than rocket engines - rockets have been around for centuries, despite a few cautious claims, I don't think anyone can say for sure their SCRAM worked! The Aussie machine looked interesting - just before it crashed.)
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

  14. #74
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    Wow - that's really cool. Would you happen to have a link to a video or story or something?

  15. #75
    Funniest man in this seat minesweeper's Avatar
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    >>Wow - that's really cool. Would you happen to have a link to a video or story or something?<<

    Sorry, it was a TV program I saw ages ago. Don't remember any details such as who was working with it or anything. I just remember the basics because it was so damn cool!!!

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