Satellite Positions

[Woggles]

Hi everyone.

I have a question regarding shift in earth axis and satellite positions. We all heard about the shift in earth axis when the earth quake hit Chile. (I quoted from a previous post, see below) Did the orbiting satellites have to be reposition after the shift in axis?


Quote "Re: 8.8 quake strikes Chile
by MeteorWayne » Thu Mar 11, 2010 6:41 pm
• Nice article about the earth's axis shift caused by the quake:
http://science.nasa.gov/headlines/y2010 ... reaxis.htm

"According to our calculations, the quake moved Earth's figure axis by about 3 inches (8 cm)," says geophysicist Richard Gross of the Jet Propulsion Laboratory in Pasadena, California.

....

A shifting figure axis is nothing new. On its own, the figure axis moves about 10 centimeters per year as a result of "Ice Age rebound." After the last great glacial period some 11,000 years ago, many heavy ice sheets disappeared. This unloaded the crust and mantle of the Earth, allowing the planet to relax or "rebound" back into a more spherical shape. The rebounding process is still underway and so the figure axis naturally moves.
...

So far, however, it's all calculation and speculation. "We haven't actually measured the shift," says Gross. "But I intend to give it a try."
...

http://science.nasa.gov/headlines/y2010 ... obble1.jpg"

 

[Shpaget]

GPS satellites are constantly monitored and their actual position in the sky is measured several times a day and compared to the position they (the satellites) believe are at. If the differ (and they usually do a bit) the 3D model with which the satellites work and calculate is updated.
So no, they were definitely not repositioned. Such a small shift would go unnoticed, or if it was noticed it was compensated in matter of hours (when the satellite passes over the measuring point).

As for other geostationary satellites (telecommunications, TV...), 10 centimeters left or right is absolutely irrelevant.

 

[Woggles]

Thanks Shpaget. I always wonder about that.