Oumuamua is apparently a cigar-shaped asteroid that recently passed through the solar system on an unusual orbit, exhibiting unexpected acceleration.

Oumuamua is known to have fairly minimal powers of thrust other than gravitational free fall, insufficient in themselves to quickly turn around and accelerate the body, but they could be sufficient to enable it to influence itself to harness the gravitational effects of surrounding planetary bodies. Assuming favourable thrust conditions, what is the soonest we could expect it to return?

*The extragravitational thrust is of unknown cause. The most popular explanation is that Oumuamua has some cometary properties and that it is caused by cometary outgassing in proximity to the Sun, although no cometary tail is apparent.

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    $\begingroup$ @user334732 - no, you have definitely not fixed the question. You wrote "is known to have fairly minimal powers of thrust" - no it doesn't. It is a rock. My vote is still very much a keep closed as entirely off topic. $\endgroup$ – Rory Alsop Mar 18 '19 at 11:07
  • $\begingroup$ @RoryAlsop sorry, I thought this fact was so well known as to be taken for granted. I've added a reference - is that better now? $\endgroup$ – samerivertwice Mar 18 '19 at 12:04
  • $\begingroup$ The outgassing is very well known. And it's incredibly small. It's a rock. $\endgroup$ – Rory Alsop Mar 18 '19 at 12:25
  • $\begingroup$ @RoryAlsop ah ok I get you know. You're saying the outgassing is only sufficient to generate fairly minimal thrust. $\endgroup$ – samerivertwice Mar 18 '19 at 12:54
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    $\begingroup$ and classing it as thrust is misguided. Outgassing is incredibly small, and it really only happened at pretty close approach to the sun. There is not going to be measurable thrust once Oumuamua is away. $\endgroup$ – Rory Alsop Mar 18 '19 at 13:02

Oumuamua as an object is remarkable, because it has a positive net energy, which means it is not bound to the gravitational well of our sun. Therefore it will never return.

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    $\begingroup$ I'm not sure that really follows Q.E.D-like, so I've just asked What natural mechanisms could lead to the unlikely case of the same rogue asteroid or planet passing through our solar system twice? $\endgroup$ – uhoh Mar 18 '19 at 7:28
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    $\begingroup$ @uhoh: Well, it does. non-bound orbits have no solutions for return times. Of course you're free to envision a unlikely multiple scattering process that would make the object return, but that's at least a three-body system then, and my statement was about the two-body system of sun and test mass. $\endgroup$ – AtmosphericPrisonEscape Mar 18 '19 at 8:22
  • $\begingroup$ That's like saying 2+3=11, then later saying "...and my statement was about base four arithmetic" ;-) Space has lots of bodies, and rogue asteroids exist only because of multi-body effects to begin with. $\endgroup$ – uhoh Mar 18 '19 at 8:26
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    $\begingroup$ @uhoh: The main bodies that affect interstellar bodies are those with significant gravity wells, namely stars. So what you just said is irrelevant. $\endgroup$ – AtmosphericPrisonEscape Mar 18 '19 at 8:42
  • $\begingroup$ I've written the linked question to explore a number of ways that "never" falls short and to provide the necessary space and venue to do so. $\endgroup$ – uhoh Mar 18 '19 at 8:49

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