Could GPS satellites be used to detect gravitational waves?

haael
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To detect gravitational waves, we set up some probe masses in laboratories far from each other and measure distance between them. Why not use GPS satellites for that? I mean: they have precise atomic clocks, they constantly measure their position relative to each other and they are as far away from each other as possible with current technology.

Has it already been done, by any chance? Has anyone tried to use GPS satellites orbit disturbances to detect gravitational waves?
 
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Their positioning system is not nearly accurate enough - the distortions expected are of the order of 10-22 and geosynchonous orbit is something like 70000km across - giving a maximum displacement of the order of femtometers(?)

However:
http://imagine.gsfc.nasa.gov/docs/features/topics/gwaves/gwaves.html
 
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For something space-based that could do the job, look up LISA.

http://lisa.nasa.gov/

It's current status seems to be in flux, people are still trying to make it happen, I don't know any of the details.
 
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