NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: FOGs
From: Frank Reed
Date: 2008 Jan 30, 19:39 -0500
From: Frank Reed
Date: 2008 Jan 30, 19:39 -0500
George, you wrote: > However, the link to the Gravity B experiment came from Paul Hirose, not > Frank. And it leads to a further question- > > That article, http://einstein.stanford.edu/sitemap.html , was written in > the future tense, describing a proposed experiment which was intended to > launch in 2003, and last for two years. So by now it should have > been-and-gone. Can anyone tell us whether it actually happened, an if so, > what the results were? Yes, that was Paul. :-) I have been following the evolution of the plans for this mission since the 1980s (the original funding for research on this project goes back to the early 1960s). The mission ran from launch in April 2004 up until the evaporation of the last liquid helium in September 2005. As for the results, the principal investigators are still working and they have not released their final results (that's due in just a couple of months). But so far, the results have been somewhat inconclusive. There was more noise in the system than expected. The gyros were torqued by patches on their surfaces with different electrostatic properties. Although the so-called "geodetic" precession has been detected, some questions have been raised about the level of confidence. And at least so far, it has not been possible to model enough of the remaining noise to see the smaller frame-dragging effect (the idea is that if you can model it reliably, you can subtract it from the observed data). Here's a press release from last spring: http://einstein.stanford.edu/content/press_releases/SU/pr-aps-041807.pdf Incidentally, there's no connection between GP-B and the earlier "Gravity Probe A" which was a high-altitude, sub-orbital flight with an atomic clock which provided detailed confirmation of special relativistic and general relativistic time dilation (the gravitational redshift). -FER --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---