Leland,

Just want you to know that I've found all these reports interesting and greatly appreciate your taking the time to post the information.

cheers
>Hi,
>
>Here is the Gravity Probe B Mission Update for Jan 28, 2005.
>
>#------------------------------------------
>
>==============================================
>GRAVITY PROBE B MISSION UPDATE FOR 28 JANUARY 2005
>==============================================
>
>GP-B Status At a Glance
>----------------------------
>Mission Elapsed Time: 283 days (40 weeks/9.25 months)
>Current Orbit #: 4,178 as of 4:00PM PST
>Spacecraft General Health: Good
>Roll Rate: Normal at 0.7742 rpm (77.5 seconds per revolution)
>Gyro Suspension System (GSS): All 4 gyros digitally suspended in science mode
>Dewar Temperature 1.82 kelvin, holding steady
>Global Positioning System (GPS) lock: Greater than 98%
>Attitude & Translation Control (ATC): X-axis attitude error: 233.5 marcs rms, Y-axis attitude error: 318.3 marcs rms
>Command & Data Handling (CDH): Multi-bit errors (MBE): 0; Single-bit errors (SBE): 8.5 (daily avg.)
>Telescope Readout (TRE): Nominal
>SQUID Readouts (SRE): Nominal
>Gyro #1 rotor potential: -13.8 mV
>Gyro #2 rotor potential: +9.2 mV
>Gyro #4 rotor potential: -12.2 mV
>Gyro #3 Drag-free Status: Backup Drag-free mode (normal)
>
>Mission Director's Summary
>-------------------------------
>As of Mission Day 283, the Gravity Probe B vehicle and payload are in good health, with all systems functioning nominally and nearly five months of science data collected. Last Thursday morning (20 January 2005), GP-B entered Safemode 2A (gyro hold), due to the loss of the guide star. Analysis of this safemode indicated that the telescope detectors were saturated by a large solar flare (X-7 class) that occurred Wednesday night. The solar flare had fluxes spiking several orders of magnitude above nominal in the > 100MeV proton energy range. Less than a day later (16:27 PST), GP-B successfully re-locked onto the guide star and the Attitude and Translation Control (ATC) system returned to its nominal configuration. During this event, the attitude error of the spacecraft and telescope remained within 800 arcseconds of the guide star. A preliminary assessment suggests that this event had minimal impact on the GP-B data or experiment.
>
>One issue currently being investigated is the spacecraft's proton monitor, which had been yielding spurious values before last week's solar storm. The proton monitor was power cycled this Tuesday night (25 January). After reboot, it provided two hours of meaningless data followed by zeros. The proton monitor team is examining the data for additional clues, and a review of this issue will be forthcoming.
>
>Mission News
>---------------
>Last week's intense solar storm has died down, and solar proton activity, as reported by the National Oceanic & Atmospheric Administration's (NOAA) Space Environment Center (SEC), has returned to normal levels. Likewise, the GP-B spacecraft has returned to normal functioning, with the ATC system locking normally on the guide star each orbit and the telescope detectors returning normal values. GP-B was not the only satellite affected by last week's solar storm; other satellites fared worse from the ordeal. In fact, given that last week's solar storm was the worst one since October, 2003, the GP-B spacecraft performed remarkably well, with a very swift recovery and no significant impact to the experiment.
>
>
>--
>**********************************
>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
>**********************************
>
>#-----------------------------------------------
>
>Regards,
>
>LelandJ