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Gravity Probe B

Testing Einstein's Universe

WEEKLY HIGHLIGHTS FOR WEEK ENDING 30 MARCH 2001:

SUCCESSFULLY COMPLETED CM-18: POST ACOUSTIC FUNCTIONAL TEST COMPLETE
The payload test team has successfully completed the post acoustic checkout of the GP-B payload. The telescope and the four flight DPAs passed a functional test and the four SQUIDs and pickup loops passed functionality and dc coupling tests. The thermal profile of the probe and dewar have been re-measured and have been found to be very similar to the pre-acoustic profile. This confirms that this hardware was not damaged by the acoustic test. A non-critical anomaly associated with the UV charge control system is under investigation. A second observation is that the magnetic flux state of either gyroscope #2 or SQUID #2 may have increased as a result of the acoustic test. If confirmed, this excess magnetic flux can be easily removed by a quick flux flushing process.

Photo: September 2000 photo of Ken Bower and the Science Instrument (containing the gyros and the SQUIDs) during final inspection before its installation into the vacuum can and later the Dewar. The completed flight Science Instrument inside the flight Dewar constitutes what is called the science payload.

SUCCESSFULLY COMPLETED PDU ACCEPTANCE DATA REVIEW
The flight PDU box successfully completed its testing and Acceptance Data Review following replacement of its internal tin gasket at Spectrum Astro in Gilbert, Arizona. The PDU is now in GP-B Flight Stores awaiting installation on the spacecraft.

Photo: LM Engineer Lim Mar inspecting the PDU in 1998.

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