LAGEOS confirms frame dragging.

[ohwilleke]

I haven't seen it posted anywhere, but unsurprisingly LAGEOS 1 and LAGEOS 2 have confirmed the frame dragging predicted by GR in the solar system within 99% of the predicted value. The margin of error was +/- 5%.

http://www.spacetoday.net/Summary/2609

 

[marcus]

I finally came across some links to journal articles about this
and posted something in relativity forum

your link points to this:
http://www.newscientist.com/news/news.jsp?id=ns99996552

and also to the Nature article (but unfortunately I don't have a subscription)

glad you called attention to this, Willecke, and my intention is, if I find any more on it, to add it to the thread in relativity forum

 

[wolram]

http://xxx.lanl.gov/pdf/gr-qc/9704065

this is a link to a 1997 paper, where a 25% accuracy is claimed,
latter revised to 20%.

 

[wolram]

http://www.phy.duke.edu/~kolena/framedrag.html

A little more info on first quoted paper.

Dr. John Ries, an expert in satellite geodesy at the
University of Texas at Austin, cautions that it is very
challenging to remove the much larger effects of tidal changes and
small zonal influences in the Earth's gravitational field, so that
estimating the possible errors in the measurement of the Lense-
Thirring effect is itself uncertain.

 

[wolram]

A snip from Wikipidia,

The 20 October 2004 online edition of Nature reports an updated analysis by Ciufolini and Pavlis of the LAGEOS data, now enhanced by using NASA's GRACE gravity model. They claim to have measured an effect which is 99% ± 5% of the value for the Earth's frame-dragging effect predicted by relativity theory, which they have revised to a ±10% error term to allow for errors not taken account of in their analysis.

 

[silverpig]

The thing with this is the method used has a huge effect on the sattelites' positions due just to the fact that the Earth isn't a sphere. They're looking for a very small deviation in the sattelites' orbits when they have already been perturbed greatly by other factors. The accuracy of their measurements hinges on knowing these other factors very precisely.