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wywong
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What is the difference between man-made satellites and the moon that causes the former to drift towards the Earth but the latter drift away?
wywong said:Thanks a lot!
Do geostationary satellites neither gain nor lose orbital angular momentum due to tidal acceleration?
jtbell said:I'd expect the tidal acceleration of artificial Earth satellites to be extremely small. Has it actually been observed?
Essentially none of it is tidal. Artificial satellites are way too small to raise significant tides on Earth.rbelli1 said:Good point. What portion of the orbital decay is tidal and what portion is atmospheric drag?
BoB
i.e. they are already 'locked'.LURCH said:No, geostationary satellites do not experience positive or negative acceleration from tidal forces (to any appreciable degree, at least). They are not orbiting faster than the Earth is revolving, so they don’t get slowed down by trying to drag the Earth along and speed it up. They are also not orbiting more slowly than the planet revolves, so they are not flung up by the Earth trying to speed them up.
No.sophiecentaur said:i.e. they are already 'locked'.
All the others are going round faster so any tidal effect would be speeding the Earth up and slowing them down. But until the total mass of artificial satellites becomes comparable with the mass of the Moon, it won't be measurable.
No; again, man-made satellites are far too small to cause noticeable tidal effects.consuli said:Thus, geostationary satellites can operate significantly longer with same amount of energy than non-stationary ones, as the first ones do have to compensate positive ore negative tidal acceleration effects during their life time?
That is not the same thing as causing decay. It just means the path taken isn't smooth. The mechanism by which the tides cause the moon to drift away requires that it be pulling against it's own tidal bulge.Nik_2213 said:Please, with disclaimer that the Earth is not uniform, it is a lumpy oblate spheroid at best, and the resulting gravity effects produce wibbles in orbits, compounded by Lunar and Solar tides.
No...Remember the difficulties Apollo etc had with Lunar mascons affecting, even destabilising low orbits ??
Geostationary communications satellites do need to expend station keeping fuel to maintain their assigned position. My understanding is that the primary influence is from the moon which tends to cause orbits to precess out of the equatorial plane.consuli said:Errata corrected
Thus, geostationary satellites can operate siginificantly longer with same amount of energy than non-stationary ones, as the first ones do not have to compensate positive ore negative tidal acceleration effects during their life time?
Man-made satellites have a specific orbit around the Earth that is carefully calculated and maintained by their propulsion systems. This orbit allows them to maintain a stable distance from the Earth and prevents them from drifting away.
Satellites stay in orbit around the Earth due to the balance between their forward motion and the pull of gravity from the Earth. Their speed allows them to continuously fall towards the Earth, but the curvature of the Earth means that they never actually reach the surface.
Yes, satellites can fall out of orbit if their propulsion systems fail or if they encounter unexpected gravitational forces from other objects in space. This can result in them either crashing back to Earth or drifting off into space.
The length of time a satellite stays in orbit depends on its altitude and the strength of its propulsion system. Low Earth orbit satellites can stay in orbit for a few years, while geostationary satellites can stay in orbit for decades.
Yes, satellites often need to be repositioned in orbit to maintain their desired orbit or to avoid collisions with other objects in space. This is typically done using their propulsion systems, but can also be done through gravitational assists from other objects.