Gaia: Focus, straylight and basic angle

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceeding


The Gaia all-sky astrometric survey is challenged by several issues affecting the spacecraft stability. Amongst them, we find the focus evolution, straylight and basic angle variations Contrary to pre-launch expectations, the image quality is continuously evolving, during commissioning and the nominal mission. Payload decontaminations and wavefront sensor assisted refocuses have been carried out to recover optimum performance. An ESA-Airbus DS working group analysed the straylight and basic angle issues and worked on a detailed root cause analysis. In parallel, the Gaia scientists have also analysed the data, most notably comparing the BAM signal to global astrometric solutions, with remarkable agreement. In this contribution, a status review of these issues will be provided, with emphasis on the mitigation schemes and the lessons learned for future space missions where extreme stability is a key requirement.


  • A. Mora
  • M. Biermann
  • A. Bombrun
  • J. Boyadjian
  • F. Chassat
  • P. Corberand
  • M. Davidson
  • F Doyle III
  • D. Escolar
  • W. L. M. Gielesen
  • T. Guilpain
  • J Hernandez
  • V. Kirschner
  • S. A. Klioner
  • C. Koeck
  • B. Laine
  • L. Lindegren
  • E. Serpell
  • P. Tatry
  • P. Thoral
External organisations
  • European Space Astronomy Centre
  • Heidelberg University
  • European Space Research and Technology Centre (ESA/ESTEC)
  • Netherlands Organisation for Applied Scientific Research (Utrecht)
  • Dresden University of Technology
  • Airbus Defence and Space SAS
  • Royal Observatory, Greenwich
  • European Space Operations Centre
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology


  • Astrometry, Basic angle, Focus, Gaia, Interferometry, Stability, Straylight, Wavefront sensor
Original languageEnglish
Title of host publicationSpace Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave
ISBN (Electronic)9781510601871
Publication statusPublished - 2016
Publication categoryResearch
EventSpace Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave - Edinburgh, United Kingdom
Duration: 2016 Jun 262016 Jul 1


ConferenceSpace Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave
CountryUnited Kingdom