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Xenon Thruster Slingshot / Space Station

  (+4)
(+4)
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Slingshots have been touted as a cheap delivery mechanism to LEO. However, up to this date none have been built due to problems with friction, G forces, and/or atmosphere density.

Xenon Thruster Slighshot is the same thing except it sits in LEO (delivered there by conventional rockets) and shoots payloads onto interplanetary trajectories.

Due to lack of air resistance and low gravity, it's ready to be built using today's technology. No need for exotic materials required. We can use xenon thrusters and plain old steel tethers. Identical slighthots can be positioned throughout the solar system to boost payloads back and forth.

Other advantage that's a fortunate side effect of the design is that now there are two permanent artificial gravity space stations available.

(see diagram - not to scale)

ixnaum, Mar 31 2019

Diagram http://florian.ca/x...uster_slingshot.png
[ixnaum, Mar 31 2019]

Momentum exchange tether https://en.wikipedi...tum_exchange_tether
What this is a type of, IIUC. [notexactly, Mar 31 2019]

Usual use of a xenon tube https://www.youtube...watch?v=mJpymZpk-t8
[bigsleep, Apr 04 2019]

[link]






       Alright, [+].   

       Before I looked at the diagram, I was imagining a long V-shaped cord with an ion thruster at each end, those thrusters acting to straighten out the cord, with the payload at the point of the V. That might have the same problem that was brought up when I proposed the idea of an electric motor-driven slingshot (using a winch in basically the same way), namely that it can't pull fast enough to work at all (which I still doubt).   

       // slighthots //   

       Warms?   

       (Off topic: I just noticed upon editing this comment that line wraps are no longer converted by the site into hard line breaks upon saving and editing! Also, I just noticed that today marks ten years since I first walked in the bakery's door as a participant, and it had mildly annoyed me that whole time, so this is a wonderful halfcakeday present! Thanks!)
notexactly, Mar 31 2019
  

       //Slighshot// Sounds Irish.
Sgt Teacup, Mar 31 2019
  

       Precision in orbital trajectory and speed could be challenging.
RayfordSteele, Apr 01 2019
  

       You don't need precison. The spaceship would be equiped with its own chemical rocker engines. So if the trajectory was 5% off you would just spend bit extra onboard fuel to make the correction. Also you would not release until the trajectory was almost perfect anyway
ixnaum, Apr 03 2019
  

       Nice. Love the diagram, but, um... any craft leaving would be flung outwards directly away from the hub or pivot. Depending on how massive the system is, compared to the craft, moving a mass towards the outer arm of a spinning system will have the effect of causing the rotation to wobble as it becomes off center. The entire system will then feel the effects of detaching the weight as the center of mass becomes the center again. (+)   

       // any craft leaving would be flung outwards directly away from the hub or pivot //   

       No, tangentially.   

       // Depending on how massive the system is, compared to the craft, moving a mass towards the outer arm of a spinning system will have the effect of causing the rotation to wobble as it becomes off center. //   

       I think that could be mostly solved by having two equal-mass payloads moving outward at the same time. Then the imbalance is only between when the first one is released and when the second one is released (assuming they aren't going in opposite directions).
notexactly, Apr 04 2019
  

       I love this idea.
Voice, Apr 04 2019
  

       I ran the numbers on this once and the G forces make it unworkable. Essentially, centrifugal force is inversely proportional to the radius but obviously the speed needs to be constant at an LEO velocity. So lets say we use a 64 km length arm, then the g forces would be 6400km / 64km = 100g. 6km arm and 1000g.   

       What's the xenon tube for ? [link]
bigsleep, Apr 04 2019
  

       //I think that could be mostly solved by having two equal-mass payloads moving outward at the same time. Then the imbalance is only between when the first one is released and when the second one is released (assuming they aren't going in opposite directions).//   

       Yep. That's what I was thinking too. If the secondary mass didn't extend at the same rate as the payload, (and of course retracted more slowly than the retreating payload after launch), then you should be able to use the wobble to your advantage for a little extra umph before the system equalizes, and if you can allow the central hub to slide back and forth at just the right speed relative to the wobble then the occupants won't feel the change at all.   

       I would like a second (+) to give please.   

       //No, tangentially.//   

       hmmm, that's not what I see in my head. If you were to suddenly stop a spinning launcher then a detached craft would leave tangentially but unless I am mistaken about the meaning of tangent then all of the force acting on the body to be released will be in direct line of site from the center of mass when you let'r go.   

       To the Google!   

       hmmm again. Time to give the internal projector a whack. I get it now. The craft does exit the spinning launcher in direct line of sight from center of mass but it also has lateral motion so the two combine.   

       Very good then. Sorry 'bout that. That wobble thing should still give you a trebuchet effect if timed right.   
      
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