Talk:Orbital station-keeping

March 2007
This page should be combined with 'station keeping', but I don't know the process to use to suggest and implement this. Andrew8

Cleanup
I cleaned up the paragraph breaks and did a little bit of copy editing. No content was changed in any of that. I also removed an irrelevant reference to Arthur C. Clarke for two reasons: 1. A reader who did not know that Clarke lives in Sri Lanka would have no idea at all why he's mentioned here; such a reader might speculate that Clarke wrote something about the stable point above Sri Lanka instead. 2. Clarke's residence in Sri Lanka has nothing to do with the stable point, or station keeping in general. If I am wrong and it does, please restore the Clarke reference with an explanation of that relevance.

What exactly is the Tennis Ball Effect?
Is this a slang term, something made up, or is it for real? Is there a tecnical term that could be substituted here, an explanation tendered, or an article written to explain the "Tennis Ball Effect"?
 * Now removed, but I understand it refers to the path a satellite takes following North-south drift and some east-west drift if all remain uncorrected. If east-west systemic drift is eliminated, satellites follow a figure-of-eight path (with the remaining east-west drift being a time of day phenomenon). If there is more systematic east-west drift, the path becomes more swirly, like the join line on a tennis ball.  Not a known scientific term but descriptive.  Martin 17:07, 19 December 2007 (UTC)  —Preceding unsigned comment added by Mpurdy (talk • contribs)

Cleaned up
I cleaned this up based on 3-4 different sources, one of which looked clean enough to be citable. Having checked up in a number of places, I've not seen any further references to the tennis ball manoeuvre, but stand willing to be corrected on it. Could use linkage to some decent pictures on the various planes, etc.

Merge proposal
The "Orbital stationkeeping" should probably be merged into this one, but I do not know the process by which that should be recommended or implemented. Andrew8
 * New discussion goes at the bottom. Thanks. –EdC 06:49, 8 March 2007 (UTC)
 * Added merge tags to both articles. –EdC 06:49, 8 March 2007 (UTC)

Given the existence of the nautical term might be better to have articles at orbital stationkeeping and nautical stationkeeping, and have this as a dab page. –EdC 22:34, 8 March 2007 (UTC)


 * I've done the latter. –EdC 23:16, 11 March 2007 (UTC)

stationkeeping vs station keeping vs station-keeping
Which one is it? Stationkeeping is not in the dictionary. I suggest rename. Objections? Javit 18:48, 28 May 2007 (UTC)
 * Which dictionary, and to what? –EdC 20:27, 29 May 2007 (UTC)
 * Meriam-Webster. Should be station-keeping according to Spacecraft System Engineering Ed. Graham Swinerd et al. WILEY. I will go ahead with it. Javit 20:35, 29 May 2007 (UTC)

GEO Station Keeping
This section seems like it repeats itself. —Preceding unsigned comment added by Jdkessler (talk • contribs) 14:42, 2 October 2007 (UTC)
 * Agreed - I put the first half in, but the second contributor has added extra useful information. Do you want to merge the two - if so, please go right ahead.  --Martin (talk) 17:16, 19 December 2007 (UTC)

Station-keeping in Lagrangian orbits
How different or similar is station-keeping in Lagrangian orbits? For example, I understat that the James Webb Space Telescope (Hubble telescope replacement/enhancer in 2015 or so) will orbit Earth-Sun L2 Lagrange point in an elliptical orbit of some 800 km diameter. What is involved in station-keeping in such an orbit? How meta-stable is such an orbit and will this require more fuel-per-spacecraft-unit-mass than required for more standard orbits? Thanks for any help or sources you can point to. Cheers. N2e (talk) 02:47, 10 January 2011 (UTC)

GEO station keeping again
The text here about station keeping for geostationary spacecraft is quite good but I think it should be put in the article Geostationary satellites. "Orbital station keeping" is in fact a very general concept, really too general to be an individual article! Here there should only be a few rather general statements and then references to the different types of station keeping strategies for the many different kinds of orbits!

Stamcose (talk) 11:59, 27 July 2011 (UTC)

Critics of the introduction
In the section above I say that in my opinion this whole matter should be re-organised!

But apart from this the introduction to this article is not really acceptable!


 * "either low earth orbit (LEO), or geostationary orbit (GEO)"

As if these were the only two types of orbits!


 * "It is especially important for satellite communications systems"

Why should this be specially important?


 * "Due to its usually low requirements for propulsive impulses the station-keeping is usually performed using attitude control system's thrusters."

Then it is the Attitude and Orbit Control System, this is the common term


 * "Station-keeping is particularly difficult for spin-stabilized satellites."

Why should this be the case?


 * "Automatic and Earth-station systems monitor a satellite's position with telemetry instrumentation and make any required corrections using on-board thruster systems."

?????. Does the author think about autonomous systems?

Stamcose (talk) 13:00, 27 July 2011 (UTC)

++++++++++++++

Here is a proposed introduction:

++++++++++++++

In astrodynamics orbital station-keeping is a term used to describe the orbital maneuvers made by thruster burns that are needed to keep a spacecraft in an particular assigned orbit.

For many Earth satellites the effects of the non-Keplerian forces, i.e. the deviations of the gravitational force of the Earth from that of a homogeneous sphere, the gravitational forces from Sun/Moon, the solar radiation pressure and the air-drag, must be counter-acted.

The deviations of the gravitational force of the Earth from that of a homogeneous sphere and the gravitational forces from Sun/Moon will in general perturb the orbital plane. For sun-synchronous orbit the precession of the orbital plane caused by the oblateness of the Earth is a desirable feature that is part of the mission design but the inclination change caused by the gravitational forces of Sun/Moon is undesirable. For geostationary spacecraft the inclination change caused by the gravitational forces of Sun/Moon must be counter-acted to a rather large expense of fuel if it should be possible to track the spacecraft with a non-steerable antenna.

For spacecraft in low orbits the effects of air-drag must often be compensated for. For some missions this is needed simply to avoid re-entry. For other missions, typically missions for which the orbit should be accurately synchronized with the Earth rotation, this is necessary to avoid that the orbital period gets shorter.

The solar radiation pressure will in general perturb the eccentricity (i.e. the eccentricity vector), see Orbital perturbation analysis (spacecraft). For some missions, for example geostationary spacecraft this must be counter-acted if it should be possible to track the spacecraft with non-steerable antenna. Also for Earth observation spacecraft for which a very repetitive orbit with a fixed ground track is desired the eccentricity vector should be kept as fixed as possible. A large part of this compensation can be done by using a frozen orbit design but for the fine control maneuvers with thrusters are needed.

For spacecraft in a halo orbit around a Lagrangian point the station keeping is even more fundamental as such an orbit is instable. Without an active control the smallest deviation in position/velocity would result in that the spacecraft would leave the orbit completely.

++++++++++++++

Any objections?

Stamcose (talk) 10:05, 28 July 2011 (UTC)


 * No objection. The new introduction is much better in my opinion. Just replace it. Mikeo (talk) 19:24, 28 July 2011 (UTC)

somebody needs to edit the picture http://en.wikipedia.org/wiki/File:Orbital_Planes.svg and make the correction: Eliptic plane --> Ecliptic plane. — Preceding unsigned comment added by 151.29.159.166 (talk) 01:56, 15 December 2012 (UTC)