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I would assume that there are other larger, more significant, forces acting on artificial satellites, but can tidal forces drastically alter the orbit of a satellite over time?

I was thinking this could especially be an issue for a satellite in geostationary orbit, because they have to be extremely precisely positioned. However, I could see this being an issue for satellites in other orbits as well, just not to the same degree.

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Tidal force acting on a natural satellite, like the moon around the earth, is the result of the deformability of the earth as the moon affects it and slowly the moon recedes from the earth. In general these tidal forces can be accelerating or decelerating :

their orbital period is shorter than their planet's rotation. In other words, they revolve faster around the planet than the planet rotates. In this case the tidal bulges raised by the moon on their planet lag behind the moon, and act to decelerate it in its orbit.

The size of the artificial satellites is such that this type of effect is very small in disturbing the orbit . After all the moon with all its size is still here and will be in orbit forever though at a distance, unless there is a collision with a third body or the sun turns nova.

The energy losses due to friction with the matter ( there is no complete vacuum) in their orbit is important and will mask any effect since the orbits are continually corrected for the losses as Whatroughbeast says in his/her answer.

The tidal bulges due to the Moon on the earth do affect satellites and have to be taken into account as discussed here.

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  • $\begingroup$ This answer is about how tidal forces effect the object that is causing the tidal forces. I don't think it would apply to a satellite, unless it's orbit is synced with the moon. If it is not synced, the tidal forces would be balanced out in the long run. $\endgroup$ – Orbit Jan 15 at 20:17
  • $\begingroup$ @Orbit the moon is a satellite $\endgroup$ – anna v Jan 15 at 20:20
  • $\begingroup$ Technically, yes. Not in normal people speaking language though. $\endgroup$ – Orbit Jan 15 at 20:22
  • $\begingroup$ This answer does not address the question at all. The only part that is relevant to the question is the last sentence, and that does not even try to answer the question. Besides that, I find your response to my comment counterproductive and rude. $\endgroup$ – Orbit Jan 15 at 23:28
  • $\begingroup$ @Orbit The answer DOES tell us that the Earth's orbital position (as well as that of the moon) changes according to tidal forces. The Earth-moon mass center orbit stays constant, as both the Earth and Moon recede from it. $\endgroup$ – Whit3rd Jan 16 at 0:38
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Satellites in geosync are not "precisely positioned". Instead, they drift around and require station-keeping thrusters. If, by "tidal forces" you mean gravitational forces associated with the sun and the moon, then the answer is yes, and the effects are quite important.

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  • $\begingroup$ I know they aren't just stuck in a "sweet spot", and I know they require station-keeping. They use station-keeping to keep them precisely-positioned, right? $\endgroup$ – CoilKid Oct 3 '15 at 3:09
  • $\begingroup$ Depends on what you consider precisely. The closest are about 73 km apart. But in the sense you mean, yes. $\endgroup$ – WhatRoughBeast Oct 3 '15 at 3:21
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No, the movement of water bodies on earth does not significantly influence the orbit of man made satellites. Due to the movement of the water, and the shape of the earth, the center of gravity of the earth shifts slightly. Sometimes this pulls the satellite a bit more to the front, and sometimes a bit more to the back (sideways is also possible). On average, the effect is zero though.

If the orbit of the satellite is exactly synced with the orbit of the moon, there would be an effect over time. In that case, extra fuel would need to be brought to keep it in orbit. See here: https://en.wikipedia.org/wiki/Tidal_acceleration

There are minor perturbations of the orbit due to tidal forces though: https://link.springer.com/chapter/10.1007/BFb0011470 They are in the order of centimeters, whereas geostationary height is 35,786 km.

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Yes, of course the tidal forces affect the orbits. In the case of the Earth/moon system, Earth's day used to be 18 hours, and when the tidal slowing got to our current 24-hour solar day(23 hours fifty-odd minutes sidereal) the angular momentum went into the Lunar orbit, and the moon is more distant nowadays.

That 18-hour day was the status quo about 900 million years ago. The moon's orbit is expanding about 3.8cm per year, and Earth's day is growing at 2 milliseconds per century. Whether you call this orbital change 'significant' or not, is a judgment call. I'd say it is significant, because the Moon wouldn't be so near unless it was created or captured more recently than the birth of planet Earth.

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  • $\begingroup$ That's quite interesting, but the question is about the orbit of man made artificial satellites. Their precise orbit is usually more of a concern because their functioning often depends on it. $\endgroup$ – Orbit Jan 16 at 20:31

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