Propellantless propulsion

Tether-satellite-NASAFollowing on from solar sails we have a discussion of that other science fictional bastion of propellantless propulsion – the space elevator – it turns out that space elevators and space tethers can be used for more than just getting into orbit:

A series of bolo tethers, each tether passing a spacecraft onto the next, could be used to achieve even larger orbit changes than a single system. For example, one tether system could catch a spacecraft from a very low orbit and swing it into a somewhat higher orbit. Another bolo picks it up from there and puts the satellite into a geosynchronous transfer orbit (GTO). A third tether catches the load again and imparts sufficient velocity to it so that it reaches escape velocity. A satellite initially orbiting just above the atmosphere could thus be slung all the way into an interplanetary orbit around the Sun, and all this without using any rocket propulsion and propellant

This is in the context of a review by Centauri Dreams of Space Tethers and Space Elevators by Michel van Pelt, which explores tethers and space elevator concepts in some detail.

[from Centauri Dreams][image from Wikimedia and NASA]

One thought on “Propellantless propulsion”

  1. I like the catching idea.

    The first step, surely, is to get a tether from a decent orbital height down to the apex of SpaceShipTwo’s flight level.
    With a counter balance thats pulled in ahead of time slowly (using solar panels), SS2 could then be winched up using nothing but the stored gravitational potential of the counter weight.

    While you have the hard part of “catching” SS2 at apex, its infinitely easier then having a full space elevator from geosycn to ground. (which mostly has to carry its own weight…even with carbon fiber your talking about insanely thick cableing).

    This on the other hand, seems achievable with todays tech.

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