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Gravity Probe B

Testing Einstein's Universe


The payload integration team has completed preparing the dewar for probe insertion. In addition the team has installed the probe into the airlock and has placed this assembly on top of the dewar. The probe has been centered over the dewar and purging of the airlock has been started in preparation for probe insertion(CM-09).

Four of the five aft GSS boxes have been assembled and are in test. The fifth box (the spare) is in rework to correct a connector orientation issue.

Photo: Tom Welsh with the flight probe. The probe is fastened at the top to the disk-like piston plate (non-flight - for the purpose of moving the probe) and hanging from a crane.

In preparation for the payload acoustic test, the flight Sunshade shutter was successfully actuated using the Attitude Control Electronics (ACE) and Sunshade Assembly Control Electronics (SACE). The shutter was closed using the Command and Telemetry Unit (CTU) and the sun sensor bright object circuit in the ACE. The shutter open and launch mode commands were also verified.

The forward ECU passed pyro shock testing. The UV lamps passed testing; indications are that their light levels are nominal. The Aft unit Vatterfly boards have been tested and are in conformal coating. Upon return next week they will be baked-out, inserted into the Aft unit and the Aft box will be formally close for resumption of protoqual testing.

The SRE is awaiting the last of the power supply boards with the replaced Interpoint DC-DC converters. Upon checkout of these boards, they will be conformally coated and the integrated Aft and Fwd units will undergo a systems level MQA at the end of October prior to resumption of protoqual/acceptance testing.

Photo: LM engineers Phillip Rittmuller and Jon Kirschenbaum with the flight Sunshade in LM B/205. Not pictured: Paul Dulgov.

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