Thanks for your continued support of Gravity Probe-B

Status Report From: Stanford University
Posted: Saturday, June 28, 2008


Since May 23, 2008, when I sent out our most recent GP-B email status update and posted the same information on our webiste (, I've received too many email responses to reply to each one individually.

Thus, on behalf of the GP-B team, I wish to thank all of you, collectively, who expressed support for GP-B, and assure you that, in the words of Mark Twain, "...Rumors of the demise of GP-B are greatly exaggerated."

Our science team is continuing to make excellent progress in the data analysis. Members of the team, including several Stanford graduate students, have produced detailed maps of the trapped magnetic flux in all four gyro rotors in order to predict the time-varying signal in the data. This mapping has resulted in a 500-fold improvement in the determination of the polhode motion throughout the duration of the experiment, essentially solving the time-varying polhode motion problem in the data.

This work, in turn, has enabled the team to implement two complementary methods of removing the disturbing effects of the classical torques. With the classical torques properly handled, rather convincing estimates of frame-dragging are now available, but our team is still investigating all possible systematic disturbing effects.

Another meeting of the GP-B Science Advisory Committee is being planned in late August to review our progress in the data analysis since last November. Also, GP-B will be a central contributor in an international workshop on "The Nature of Gravity: Confronting Theory and Experiment in Space" to be held in Bern, Switzerland, 6-10 October 2008, with the following team members as individual invited speakers: William Bencze, Francis Everitt, Misha Heifetz, George Keiser, Barry Muhlfelder & Alex Silbergleit.

Meanwhile, we are vigorously exploring funding sources outside NASA, both through other agencies and private donors, to enable GP-B to complete the data analysis, publish the final results and bring GP-B to a conclusion by early 2010.

We very much appreciate the continued interest and support we have received world-wide, and we will keep you apprised of our status going forward.


Bob Kahn GP-B Public Affairs

NASA - Stanford - Lockheed Martin Gravity Probe B Program

"Testing Einstein's Universe"

Bob Kahn
Public Affairs Coordinator & Webmaster

Phone: 650-723-2540
Fax: 650-723-3494

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