The Gaia mission1 will create an extraordinarily precise three-dimensional map of more than one billion stars in our
Galaxy. The Gaia spacecraft2, built by EADS Astrium, is part of ESA's Cosmic Vision programme and scheduled for
launch in 2013. Gaia measures the position, distance and motion of stars with an accuracy of 24 micro-arcsec using two
telescopes at a fixed mutual angle of 106.5°, named the ‘Basic Angle’, at an operational temperature of 100 K. This
accuracy requires ultra-high stability at cryogenic conditions, which can only be achieved by using Silicon Carbide for
both the optical bench and the telescopes. TNO has developed, built and space qualified the Silicon carbide Basic Angle
Monitoring (BAM) on-board metrology system3 for this mission, measuring the relative motion of Gaia’s telescopes with
accuracies in the range of 0.5 micro-arcsec. This is achieved by a system of two laser interferometers able to detect
Optical Path Differences (OPD) as small as 1.5 picometer rms. Following a general introduction on Gaia and the use of
Silicon Carbide as base material this paper addresses the specific challenges towards the cryogenic application of the
Gaia BAM including design, integration and verification/qualification by testing.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
W. Gielesen ; D. de Bruijn ; T. van den Dool ; F. Kamphues ; J. Mekking, et al.
Gaia basic angle monitoring system
", Proc. SPIE 8863, Cryogenic Optical Systems and Instruments 2013, 88630G (September 27, 2013); doi:10.1117/12.2026928; http://dx.doi.org/10.1117/12.2026928