[FPSPACE] FW: Gravity Probe B Update --May 23, 2008

Tue May 27 09:26:23 EDT 2008



>From: Bob Kahn <kahn at relgyro.stanford.edu>
>To: gpb-update at lists.stanford.edu
>Subject: Gravity Probe B Update --May 23, 2008
>Date: Mon, 26 May 2008 18:47:13 -0700
>
>================================
>GP-B STATUS UPDATE -- MAY 23, 2008
>================================
>
>NASA's 2008 SENIOR REVIEW OF GP-B
>
>In March 2008 at NASA's invitation, we submitted a proposal to the Science 
>Mission Directorate, Astrophysics Division Senior Review of Operating 
>Missions (Sr. Review), requesting a final 18-month (October 2008 through 
>March 2010), $3.8M extension of GP-B to complete the data analysis and 
>publish the results. In April, as part of the Sr. Review process, GP-B 
>Principal Investigator, Francis Everitt, and Program Manager, William 
>Bencze, made a presentation to the Sr. Review Committee at NASA 
>Headquarters, where it appeared to have been favorably received.
>
>Thus, we were greatly surprised last week to discover that the Sr. Review 
>had recommended that NASA not grant our final funding extension, 
>particularly since another NASA committee--the GP-B Science Advisory 
>Committee (SAC -- http://einstein.stanford.edu/MISSION/mission2.html#sac), 
>chaired by relativistic physicist Clifford Will--stated in its report 
>following the November 2007 meeting: "The SAC was impressed with the truly 
>extraordinary progress that has been made in data analysis since SAC-16 
>[Mar 2007] Š and we now agree that GP-B is on an accelerating path toward 
>reaching good science results."
>
>The Sr. Review evaluation is an unexpected setback, but we are determined 
>to push ahead and drive to the very best possible result within the 
>resources available.
>
>THE PLIGHT OF FUNDAMENTAL PHYSICS RESEARCH AT NASA
>
>While the Sr. Review outcome has ramifications for GP-B, in broader terms, 
>it points to the challenge of finding support for fundamental physics 
>experiments within the NASA culture of observational missions. This has 
>been an ongoing issue within NASA for decades. In the 1990s, fundamental 
>physics research experiments were scattered over several divisions of NASA, 
>which led in 1999, to the blue-ribbon NASA Advisory Council (NAC) 
>recommending to the NASA Administrator that the agency create a "single 
>home room" for physics missions in space so that these missions would be 
>given the support and visibility they deserved.
>
>The 1999 NAC committee's advice was never heeded. Furthermore, during the 
>2004 restructuring and consolidation of NASA divisions, the already small 
>budget for fundamental physics research was cut to zero in the NASA 
>Exploration Directorate, entirely eliminating fundamental physics research 
>from that division. This left the Science Mission Directorate (SMD) as the 
>only home for fundamental physics experiments like GP-B. However, in the 
>SMD, physics experiments had to compete directly with the NASA Great 
>Observatories and other astrophysics missions for pieces of an 
>already-decimated research budget. It is no criticism of the SMD Sr. Review 
>to say that of the ten missions under review, GP-B as a physics experiment 
>rather than an observatory was quite unlike the rest and almost impossible 
>to fit within a common intellectual framework. Regrettably, since NASA has 
>failed to establish a fundamental physics research division, several 
>missions besides GP-B have suffered. If such a division existed, we believe 
>the agency's support for the proper completion of GP-B would continue to be 
>strong.
>
>THE CONTINUED RELEVANCE & IMPORTANCE OF GP-B
>
>One of the Sr. Review Committee's main arguments supporting its 
>recommendation that NASA not fund the final extension requested by GP-B, 
>was that the goals of GP-B have already been fulfilled by other 
>measurements, and that GP-B is therefore no longer relevant. This view is 
>in stark contrast with the recommendations of the SAC (2007), NASA's Turner 
>panel review of GP-B (2003), and NASA's Fitch-Taylor NRC review of GP-B 
>(1995). All of these reviews concluded that the GP-B experiment is 
>scientifically justified and should be completed.
>
>Now, in 2008, the scientific justification for completing the GP-B 
>experiment is even more valid. During the past five years, there has been 
>little progress on other relativity experiments, but GP-B was launched, 
>operated, and collected all of the necessary data. After two years of 
>intense work, the GP-B science team is very close to completing the data 
>analysis. GP-B has made, in the view of the SAC, "extraordinary progress" 
>in addressing two unexpected and difficult complications in analysis caused 
>by unanticipated electrostatic patch effect fields within the gyroscope. 
>(These have been reported previously in our Summer 2007, September 2007 and 
>December 2007 status updates, which you can view in the STATUS tab on our 
>Website: http://einstein.stanford.edu/highlights/hlindexmain.html)
>
>GP-B directly studies gravity, one of the most fundamental laws of nature. 
>Inherently, the goals of GP-B differ significantly from those of typical 
>astrophysics missions, where natural laws--inferred theoretically and 
>tested on the ground--are used to interpret observations of astrophysical 
>phenomena. Furthermore, GP-B objectives and methods are qualitatively 
>different from those underlying most astrophysical work. For this reason, 
>the GP-B experiment begs to be evaluated with respect to criteria based on 
>its direct experimental methodology. Direct tests of nature's laws are the 
>foundation of physical science; such tests are the only rational basis for 
>the belief that these laws are, in part, "understood."  GP-B seeks to 
>deepen our understanding of gravity in this way.
>
>In addition to its scientific significance, GP-B's technological heritage 
>and operational experience is critically important for future gravity space 
>missions, including tests of the equivalence principle (STEP) and the 
>search for gravitational waves (LISA). NASA stands to loose much of the 
>expertise developed on the GP-B mission if the program is not brought to a 
>proper conclusion.
>
>THE ROAD AHEAD
>
>Our GP-B team has been making steady progress in analyzing the data and 
>working through the unexpected complications discovered within the data. We 
>are now in the home stretch. We have identified the issues that still need 
>to be addressed, and we have prepared a sound plan for completion of the 
>analysis. This plan, which was spelled out in detail in our proposal to the 
>NASA Sr. Review, requires an additional 18-month investment of $3.8M from 
>September 2008 through March 2010. If no further funds are forthcoming from 
>NASA, the analysis efforts will likely cease by October 2008, unless other 
>funding sources can be identified. Since February 2008, GP-B has been 
>funded by contributions from NASA, Stanford University, and a private 
>donor, in approximately equal shares.
>
>We have now clearly confirmed the geodetic effect to a precision of less 
>than 1.5% (97 milli-arcseconds/year). However, because the frame-dragging 
>effect is ~170 times smaller, removing the sources of error from that 
>measurement--especially the non-relativistic torques due to patch effect 
>interactions between the gyro rotors and their housings--is a detailed, 
>painstakingly slow process. We have yet to reach a point of diminishing 
>returns. Until we do, it is our intention to push onward and obtain the 
>best result possible to properly complete this landmark experiment.
>
>We will continue to keep you posted on our progress.
>
>
>===================
>PREVIOUS GP-B UPDATES
>===================
>If you wish to read any of our previous updates, our GP-B Web site includes 
>a chronological archive of all the updates/highlights (with photos and 
>drawings) that we have posted over the past 8 years: 
>http://einstein.stanford.edu/highlights/hlindexmain.html
>
>=============================
>OTHER LINKS THAT MAY INTEREST YOU
>=============================
>
>Our NEW AND IMPROVED GP-B Web site, http://einstein.stanford.edu contains 
>lots of information about the Gravity Probe B experiment, general 
>relativity, and the amazing technologies that were developed to carry out 
>this experiment.
>
>Video and/or audio of May 18, 2006 public lecture by Principal 
>Investigator, Professor Francis Everitt, on GP-B. You can view a Flash 
>video of the lecture in your Web browser: 
>http://einstein.stanford.edu/Media/Everitt_Brainstorm-flash.html You can 
>also download either a video or audio only copy of the lecture to an iPod 
>from the Stanford University iTunes U Web site: http://itunes.stanford.edu, 
>This Web page automatically launches the Apple iTunes program on both 
>Macintosh and Windows computers, with a special Stanford on iTunes U "music 
>store," containing free downloads of Stanford lectures, performances, and 
>events. Francis Everitt's "Testing Einstein in Space" lecture is located in 
>the Faculty Lectures section. People with audio-only iPods can download the 
>version under the Audio tab; people with 5th generation (video) iPodfs can 
>download the version under the Video tab.
>
>Visual tour of the GP-B spacecraft and payload from our GP-B Web site: 
>http://einstein.stanford.edu/content/vehicle_tour/index.html
>
>PDF file containing a 1/20 scale, paper model of the GP-B spacecraft that 
>you can download  print out, and assemble: 
>http://einstein.stanford.edu/content/paper_model.
>
>NASA's Marshall Space Flight Center also has a series of Web pages devoted 
>to GP-B: http://www.gravityprobeb.com
>
>The Harvard-Smithsonian Center for Astrophysics (Cambridge) and York 
>University (Toronto), with contributions from the Observatoire de Paris, 
>have been studying the motions of the guide star, IM Pegasi for over a 
>decade.  To find out more, visit: http://www.yorku.ca/bartel/guidestar/
>
>In addition, you'll find information in the Guide Star FAQ on our Web site: 
>http://einstein.stanford.edu/TECH/technology1.html#telescope
>
>==========================
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>--
>**********************************
>NASA - Stanford - Lockheed Martin
>    Gravity Probe B Program
>"Testing Einstein's Universe"
>  http://einstein.stanford.edu
>
>Bob Kahn
>Public Affairs Coordinator
>
>Phone: 650-723-2540
>Fax:   650-723-3494
>Email: kahn at relgyro.stanford.edu
>**********************************

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