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In this question someone mentioned the idea of a Statite, a satellite which is stationary above a planet without being in orbit, usually in an orientation which is not possible with an orbit. It seems for obvious reasons that this could be particularly useful for observation of a region which isn't along the rotational path of the planet (can't use GSO to maintain line of sight) such as the poles.

Apparently this form of satellite was patented by Robert L. Forward but mentions of the feasibility of this type of satellite and whether or not anyone has seriously considered using one were omitted in many sources I've found.

Note: Lagrange orbits are technically a statite orbit, but they use another body to balance out the gravity. I'm talking about a statite which actively fights gravity, not one at an equilibrium point.

Usually a statite seems to do the following:

  • Uses a method of propulsion that is "infinite"/sustainable (such as solar sails).
  • Hovers in a single location above a body, maintaining the distance (but not necessarily attitude) with a near zero velocity relative to that body.

I suppose my overall questions would be:

  • Is this form of satellite purely hypothetical?
  • Can anyone find any mission proposals for a statite-like mission?
  • Is it proven mathematically to be possible/stable for extended periods of time?
    • If it is, are there specifics? How big would this crazy device need to be?

Note: I specifically mention Polar statite because that's the only application I can think of, if there is a proposal for a non-polar statite or something else, feel free to share that as well.

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  • $\begingroup$ There was an offhand comment in the Centauri Dreams book which suggestes the closest a polar statite could get to Earth was 250 diameters, but it didn't come with any references or working or description of the specific statite or mention of whether this was a general constraint. Anyone else seen anything on that subject? $\endgroup$
    – Starfish Prime
    Nov 26, 2019 at 21:38
  • $\begingroup$ @Starfishprime yes! An answer like that would be amazing, I've never heard of that book either, I'll look into it the few excerpts from his site seem amazing. $\endgroup$
    – Magic Octopus Urn
    Nov 26, 2019 at 21:43
  • $\begingroup$ Do satellites sitting at Lagrangian points count as statites? They can remain there for a very long time using only a tiny amount of fuel for station-keeping - maintaining the position against minor gravitational instabilities moving them out of the unstable balance position. $\endgroup$
    – SF.
    Nov 27, 2019 at 13:58
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    $\begingroup$ Also, Hayabusa2 was practically a statite of its asteroid, flying to and fro, treating the asteroid's gravity more as a low-impact disturbance in its flight paths and parking positions, rather than a driving force of a typical satellite, around which all maneuvers are planned. $\endgroup$
    – SF.
    Nov 27, 2019 at 14:07
  • $\begingroup$ @SF that's a good one, technically. I was thinking more on the macro scale in terms of a larger body with a significant gravitational pull in which an orbit would normally be required. $\endgroup$
    – Magic Octopus Urn
    Nov 27, 2019 at 16:59

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"Yes", sort of, there have been some missions proposed and yes, as you mention, they mainly use solar sails. Actual mission proposals have focused on what reasonable, state-of-the-art solar sails could really do. This limits them to working in places where other orbital forces are easier to counteract.

Probably the one that is furthest along (although, I believe, cancelled) was/is Geostorm. It is a mission to an 'artificial Lagrange point' - a point near but not at an Earth-Sun Lagrange point. The idea is to be a statite of the Lagrange point, not necessarily a body like the sun, which it still orbits. The solar sail lets the spacecraft move closer to the sun and thereby provide more warning about solar storms, but still relies on the lower orbital perturbations around the Lagrange point for most of its stabilization.

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  • $\begingroup$ I wonder if, in the long run, it could be more stable than a NRHO. That is such an interesting concept. It's crazy how much science goes into improving the solar warning time by 1 hour. $\endgroup$
    – Magic Octopus Urn
    Nov 26, 2019 at 23:39

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