The Liege thermal vacuum optical bench (FOCAL) was used to control the mechanical stability of the structure of the European Space Agency's HIPPARCOS astrometry payload. The payload is designed to measure angles of .001 arcsec between stars during 2.5 years and this accuracy can only be reached with the extreme stability of the device. The structure of the payload is made of carbon fiber; it is thermally stabilized with an accuracy of .01 degrees C. During the test, the payload is enclosed in a shell made of shrouds having a geometry close to the shading structure of the spacecraft. The shroud temperatures are defined by the conditions in orbit, e.g., the spacecraft is spinning in front of the Sun with a period of two hours and the temperature of the shrouds is cycled around the payload with a 2 hour period. In order to avoid disturbances by vibrations, the payload is put on an adapter interfaced with the optical bench and the seismic block; the shrouds are supported by a carrier with no direct interface with the table. This method avoids perturbances brought about by the cooling fluid of the shrouds.
Test of the Hipparcos payload in the Liege vacuum facility focal
1986-01-01
Conference paper
No indication
English
AIAA | 1982
|Overview of the Hipparcos Payload
NTIS | 1989
|Liege brake and wheel facility
Emerald Group Publishing | 1999
NTRS | 1991
Elsevier | 1991
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