Here is the news from the folks at Garvity Probe B:

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GRAVITY PROBE B MISSION UPDATE FOR 11 OCTOBER 2006
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GP-B DATA ANALYSIS STATUS
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Note: A more complete status overview of the GP-B data analysis process & results announcement is posted at the top of our GP-B Home page: http://einstein.stanford.edu. Following is a brief summary of our activities and accomplishments during the past month.

We are now proceeding with Phase III, the final phase-of the data analysis, which will last until January-February, 2007. Whereas in Phases I and II the focus was on individual gyro performance, during Phase III, the data from all four gyros is being integrated over the entire experiment. The results of this phase will be both individual and correlated changes in gyro spin axis orientation covering the entire 50-week experimental period for all four gyros.

At the end of Phase III, playing the role of our own harshest critic, our science team will then perform a careful and thorough final review of the analysis and results, checking and cross-checking each aspect to ensure the soundness of our procedures and the validity of our outcomes. We will then turn the analysis and results over to the SAC, which has been closely monitoring our experimental methods, data analysis procedures, and progress for 11 years, to obtain its independent review. Moreover, we will seek independent reviews from a number of international experts.

In addition to analyzing the data, members of our team are now in the process of preparing scientific and engineering papers for publication in late 2006-2007. We have also begun discussions with NASA to plan a formal public announcement of the results of this unprecedented test of General Relativity. We expect to make this announcement of the results in April 2007.


GP-B SPACECRAFT & PAYLOAD STATUS AT A GLANCE
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Mission Elapsed Time: 903 days (129.0 weeks/ 29.6 months)
--IOC Phase: 129 days (4.2 months)
--Science Phase: 352 days (11.6 months)
--Final Calibration Phase: 43 days (1.3 months)
--Extended Science Phase: 4 days
--Post Mission Phase: 375 days (53.6 weeks/ 12.3 months)
Current Orbit #: 13,320 as of 12:00 PM PDT
Spacecraft General Health: Good
Roll Rate: 0.15 rpm (6.67 minutes per revolution)
Gyro Suspension System (GSS): Gyro #1 in analog backup suspension mode; gyros #2, #3, and #4 digitally suspended
Gyro Spin Rates: N/A; gyro rotors "tumbling" slowly, rather than spinning
Dewar Temperature: ~251K (-26C) and falling slightly; Outer shell temperature: ~229K (-48C) and falling
Global Positioning System (GPS) lock: Nominal
Attitude Control System: Magnetic Sensing System (MSS) control
Pointing Error: (XY/Pitch-Yaw Axes) 2.0 degrees RMS;
Roll Phase (Z Axis) Error: 5.8 degrees RMS
Telescope Readout: Pointing performance too low to lock onto guide star
Command & Data Handling (CDH): B-side (backup) computer in control
Multi-bit errors (MBE): 4 in CCCA Backup computer; 9 in GSS computers; 0 in SRE computers (turned off)

MISSION DIRECTOR'S SUMMARY
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On Mission Day 903, both the GP-B space vehicle and payload remain in good health. All active subsystems, including solar arrays/electrical power, Experiment Control Unit (ECU), flight computer, star trackers, magnetic sensing system (MSS) and magnetic torque rods, gyro suspension system (GSS), and telescope detectors, are performing nominally. The spacecraft is now ready to be placed in a hibernation state.

During September, our small mission operations team finished upgrading various on-board systems and software that will enable the spacecraft to be placed in a hibernation state. These preparations included reducing the roll rate of the spacecraft from 0.04 rpm to 0.01 rpm and optimizing the Attitude and Translation Control system (ATC) to be consistent with this roll rate. Note that in comparison with the science mission roll rate of 0.7742 rpm (77.5 seconds per revolution) the spacecraft is now barely rolling at all (100 minutes per revolution).

However, the most important hibernation change, described in several previous GP-B updates, is the reconfiguration of the spacecraft's communications equipment to prevent it from automatically turning itself on and transmitting data in response to a safe mode condition or on-board computer reboot. During the science phase of the mission, just about any anomalous behavior on board the spacecraft would immediately trigger the spacecraft's communication system to begin streaming data so that our mission operations team could detect and troubleshoot anomalies as quickly as possible. Now that the mission has ended and we are only monitoring the spacecraft's status once a week, it is important that the spacecraft not be sending out signals that no one is monitoring and that could interfere with the operation of other spacecraft. Thus, we have now set up the spacecraft to only transmit when commanded to do so from the ground, using a robust communications channel.

All of the hibernation modifications to spacecraft systems and software have now been implemented and tested, and we plan to place the spacecraft in hibernation mode beginning next week.

Arrangements for the United States Air Force Academy (USAFA) to use the spacecraft part time--shared with our use here at Stanford--as a space operations training vehicle are now in the final stages. Members of the USAFA spacecraft operations will soon visit Stanford to take delivery of a ground station communications POD-a set of computer consoles-that they will take back to the academy in Colorado Springs to enable them to communicate with the spacecraft from there. It is anticipated that the USAFA will begin controlling the GP-B spacecraft sometime this month.

NEW PAPERBACK EDITION OF ALBERT EINSTEIN'S BOOK ON RELATIVITY
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In 1916, shortly after completing his work on the general theory of relativity, Albert Einstein published a short book entitled, "The Special and General Theory of Relativity," to help the lay public understand his theory.

Now, some 90 years later, Penguin Books has re-published an English translation of this book in a paperback edition, including an introduction by physicist Roger Penrose, scientific commentary on the special and general theories of relativity by physicist Robert Geroch, and commentary on the cultural legacy of Einstein's theories by historian David Cassidy. For more information, see the listing for this book on the Penguin Group Web site or at Amazon.com/Borders or Barnes & Noble.

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NEXT SCHEDULED GP-B UPDATE IN EARLY NOVEMBER 2006
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Our next regularly scheduled update will be at the beginning of November. Of course, we will send out a timely update if there are any important changes in the spacecraft's status, or if noteworthy events occur here at GP-B in the meantime.
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PREVIOUS GP-B UPDATES
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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

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OTHER LINKS THAT MAY INTEREST YOU
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* Our 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 streaming video of the lecture in your Web browser: http://einstein.stanford.edu/highlights/hl_video_everitt051806.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/content/faqs/faqs.html#guidestar and on pages 18-20 of the Gravity Probe B Launch Companion: http://einstein.stanford.edu/highlights/GP-B_Launch_Companion.pdf


* The Einstein Exhibition at the Skirball Cultural Center in Los Angeles has closed.However, you can visit the American Museum of Natural History's virtual Einstein exhibit on the Web at: http://www.skirball.org/exhibit/amnh_frame.html


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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@relgyro.stanford.edu
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Regards,

LelandJ