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Herschel-SPIRE Testing at ESTEC

Herschel-SPIRE Testing at ESTEC

23 October 2006

Between Tuesday, 16 October 2006 and Saturday, 21 October 2006 an engineering radiated susceptibility test and a straylight verification test have been performed at the ESTEC test centre in the frame of the Herschel PLM STM2 programme.

The Herschel cryostat and mock-up SVM in the ESTEC cleanroom

The Herschel flight cryostat was equipped with a mechanical thermal dummy of PACS (Photodetector Array Camera and Spectrometer) FPU (Focal Plane Unit), and the cryogenic qualification models of HIFI (Heterodyne Instrument for Far Infrared) FPU and SPIRE (Spectral and Photometric Imaging Receiver) FPU. The cryostat was mated to a Service Module (SVM) mock-up. On the mock-up, one panel simulator was installed, which houses three warm SPIRE units (DPU, FCU, DCU) required to operate the SPIRE instrument during the tests. No other instrument unit was present on the SVM, since SPIRE was the only instrument operated during the tests. SPIRE received the power from the satellite EGSE (Electrical Ground Support Equipment), but commanding and telemetry was done directly via the SPIRE instrument EGSE.

E-field Antenna in front of Herschel

The objective of the engineering radiated susceptibility test was to further investigate an E-field susceptibility of SPIRE initially found during the EQM campaign in 2005 at Astrium, Ottobrunn in Germany. During last week’s test at ESTEC, the cryostat has been exposed to E-field radiation in the frequency range 20-80 MHz. A large amount of scientific data was produced which needs to be analysed in detail to fully understand the results and arrive at a final conclusion.

The IR blackbody radiation source

The straylight test has been performed to determine if the measurements with SPIRE are not disturbed by straylight, in particular by straylight entering the cryostat via the HIFI LOU window. To this end the HIFI LOU window was illuminated by a hot black body source. During additional measurements, the thermal shield temperatures and the cryocover mirror temperatures were varied to analyse the impact on the scientific performance of SPIRE. Initial results indicate that the straylight level measured by SPIRE is negligible.

Last Update: 1 September 2019
25-Apr-2024 12:19 UT

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