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How space shuttles maneuver or could maneuver.

  1. Nov 25, 2003 #1
    As far as I know (and I may be horribly wrong), aside from the maneuvering that occurs during takeoff and landing, space shuttles fly in a completely straight course propelled only by inertia.

    Firstly, I'd like to know if that's right or not.

    Secondly, I'd like to know if space shuttles begin to maneuver themselves into a proper landing trajectory before or after they actually enter earths atmosphere.

    Thirdly, just out of curiosity, would space shuttles which can direct themselves with the same relative ability of planes be at all practically possible with using current methods of propulsion, or will I have to wait for a new method of propulsion before star wars style dog fights happen?
     
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  3. Nov 25, 2003 #2

    selfAdjoint

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    Well, not a "straight" course. since they are in orbit. :=)

    I do believe they can change attitude though.
     
  4. Nov 25, 2003 #3
    I need to learn to be more specific, I meant a space shuttle that is travelling to another celestial body.
     
  5. Nov 25, 2003 #4

    chroot

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    The space shuttle does not travel to any other celestial bodies.

    The space shuttle has a very sophisticated orbital maneuvering system (OMS) and reaction-control system (RCS) capable of changing orbits and attitude, respectively. If the shuttle was just a ballistic spacecraft, the astronauts aboard it would not be able to select when they re-enter, nor would they be able to put the craft into the right attitude to survive that re-entry.

    And yes, the shuttle assumes its proper re-entry attitude before the de-orbit OMS burn that brings it back into the atmosphere.

    - Warren
     
  6. Nov 25, 2003 #5

    chroot

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  7. Nov 25, 2003 #6

    enigma

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    Echoing what had been said already, they are in orbit, so it isn't a straight line.

    They generally don't do much in the way of maneuvering once they have attained orbit. They maneuver to get to their mission's orbit, do the mission, and then maneuver to get out of orbit.

    Here is a site describing an orbit (it may not be the best... I just picked the first decent one which popped up googling for Keplerian Orbital Elements

    http://www.amsat.org/amsat/keps/kepmodel.html

    A picture to go along with it is here:

    http://www.profc.udec.cl/~gabriel/tutoriales/rsnote/cp5/5-5-1.gif

    Before. They do a burn which puts them in a flight path angle (velocity to local horizontal) of about 2-3 degrees at an altitude of about 120km up. Their orientation during the reentry is at roughly 40 degrees angle of attack.

    No, it wouldn't be possible. A ship in orbit has a speed of many kilometers per second. To change course requires huge expenditures of fuel: usually a few times the mass of the spacecraft without fuel for large changes.

    Like was said, the shuttle doesn't leave low Earth orbit: it doesn't carry enough fuel. Even if it did, you'd still be travelling an ellipse around the sun. You never just go straight.
     
  8. Nov 26, 2003 #7

    jimmy p

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    I thought in last PF, myself and Andy started a thread on this. Do you mean the ship is in orbit or just in space? I would have thought that, with all the boosters in the right place, a space shuttle would be one if not the most manouverable thing we know (well....man made and in space), it is (relative) more manouverable than a fighter jet like an F14. Just strap on a couple of laser guns and proton torpedoes and you have the ugliest starfighter in the known universe
     
  9. Nov 26, 2003 #8

    russ_watters

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    Re: Re: How space shuttles maneuver or could maneuver.

    Actually, there isn't any reason why a couple of spacecraft couldn't do a Star-Wars style dogfight while in orbit. Its all about frame of reference - "stationary" is what the space station is relative to the spacecraft. "Forward" and "backward" at a few hundred m/s would be measured relative to the space station, not relative to a stationary point above earth.

    Thats basically the way it works in Star Wars too, though they don't make any disctinction between flying in deep space and in orbit. But the fighters buzzing around the Death Star while its orbiting Endor are using the Death Star as a stationary frame of reference.

    I realize the laws of orbital mechanics don't quite allow this, but as long as you keep the distance from the stationary reference point small and come back to it at the end of the fight, there isn't much deviation.
     
  10. Nov 26, 2003 #9

    LURCH

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    Re: Re: Re: How space shuttles maneuver or could maneuver.

    Although I agree that the volocity should be measured relatively, this is not the main problem. The trouble with Star Wars-style dogfights in space is the way in which fighter craft accelerate (change direction). In a vacuum, banking to one side and then "pulling up" the nose would not have the effect one sees on the screen. At least, not with current propulsion technology (as asked in the original post).

    If you've ever seen a television series called "Babylon 5", there are some fairly realistic space combat scenes in that. But even these scenes would not be possible with current tech. It's just too fuel-consuming; the amount of thrust they display would require way more fuel than could fit in a craft that size using any currently-known fuel source.

    But at least the B-5 space combat scenes would be possibe with currently understood physics and a better (more pwerfull) fuel. The type of manuevering seen ni Star Wars and most other space movies would require a new kind of physics to provide something for the craft to "push off" from. Like maybe the Ether or something.
     
  11. Nov 26, 2003 #10

    enigma

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    Not to mention that you need to slow down if you want to catch up to things ahaid of you...


    etc...

    Maneuvering in space is completely different than anything you're used to on Earth (or anything you've seen on TV).
     
  12. Nov 26, 2003 #11
    When I said space shuttle, I guess i used the wrong word all together, I was meaning to refer to the type of crafts which have been used to go to the moon.
     
  13. Nov 26, 2003 #12

    LURCH

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    I thought that was what you meant. That would be a sace capsule. And they are even less able to manuever than the shuttle. Their fuek requirements are so high that the amount of fuek carried onboard is calculated almost down to the droplet; just barely enough to get their and de-orbit when they get back, and not the slightest bit to spare.
     
  14. Nov 26, 2003 #13

    enigma

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    Re: Re: How space shuttles maneuver or could maneuver.

    Just caught this. The shuttle takes up to 2 minutes to rotate 90 degrees. Comparing it to an aircraft, it's less maneuverable than the Wright Flyer.
     
  15. Nov 28, 2003 #14

    jimmy p

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    oh right, my physics teacher is a liar in that sense, but i suppose a more advanced space craft should be extremely manouverable.
     
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