Euclid

Astronomy and Astrophysics, vol. 709, pp. A15

Abstract

Context . The performance of the Euclid system is defined in terms of image quality metrics tuned to the weak gravitational lensing cosmological probe. The weak lensing measurement induces stringent requirements on the shape and stability of the VIS instrument system point spread function (PSF). The PSF is affected by error contributions from the telescope, the focal plane, and image motion, and it is controlled by a global error budget, with error allocations for each contributor. Aims . During development of the spacecraft, we verified through a structural-thermal-optical performance (STOP) analysis that the built and verified telescope with its spacecraft interface meets the in-orbit steady-state and transient image quality requirements under temperature-induced loads in all permitted spacecraft attitudes after all permitted attitude transitions. Based on data from its first year in orbit, we compared the performance we expected with the actual performance. Methods . For the purposes of the STOP analysis, we set up a detailed finite-element mathematical model and defined a standard set of test cases, both steady-state and transient, comprising combinations of worst-case boundary conditions. Iterations of the analysis were performed in conjunction with the major reviews of the spacecraft verification cycle. After launch, we applied the model in sensitivity analyses using realistic boundary conditions. Results . The STOP analysis addressed the interaction of all spacecraft components in transmitting temperature-induced loads that lead to optical train deformation. The results of the prelaunch analysis demonstrated that temperature-induced optical perturbations would be well below the allowable limits for all permitted observing conditions. We used the STOP analysis predictions to help interpret the measured performance of the spacecraft as a function of environmental variables during its first year in orbit. We discovered unpredicted disturbances (heat pulses from instrument operation propagating into the telescope), and unexpected sensitivities (e.g. a high dependence of the telescope baseplate temperature on the solar aspect angle; a nearly absent dependence on the azimuth angle after the attitude domain was redefined for stray light avoidance). In-orbit temperature variations are small (<300 mK) and so are their effects on the telescope structure (displacements <1 μm, rotations <1 μrad), but they are detected in the time histories of the image quality metrics and are a non-negligible factor in the point spread function stability budget demanded by the weak lensing science (Δ e < 2×10 −3 over 11 000 s). Taking everything into account, our analysis confirms the overall excellent performance of the telescope.

Authors 55

1. Giuseppe D. Racca Aachen Leiden Observatory

   Leiden University · European Space Agency · Leiden Observatory · European Space Research and Technology Centre

   Affiliation as printed

   European Space Agency/ESTEC

   Leiden Observatory, Leiden University

   ESA - Agence Spatiale Européenne = European Space Agency (Agence spatiale européenne (ESA) 8-10, rue Mario Nikis F-75015 Paris - France)

2. Vincenzo Mareschi

   Thales Alenia Space (France)

   Affiliation as printed

   Thales Alenia Space – Euclid satellite Prime contractor

3. Adam Amara

   University of Surrey

   Affiliation as printed

   School of Mathematics and Physics, University of Surrey, Guildford

4. N. Auricchio

   Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics

   Affiliation as printed

   INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna

5. Carlo Baccigalupi

   Scuola Internazionale Superiore di Studi Avanzati · Trieste Astronomical Observatory · Istituto Nazionale di Fisica Nucleare, Sezione di Trieste · Institute for Fundamental Physics of the Universe · National Institute for Astrophysics

   Affiliation as printed

   IFPU, Institute for Fundamental Physics of the Universe

   INAF – Osservatorio Astronomico di Trieste

   INFN, Sezione di Trieste

   SISSA, International School for Advanced Studies

6. Marco Baldi

   Istituto Nazionale di Fisica Nucleare, Sezione di Bologna · Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics · University of Bologna

   Affiliation as printed

   Dipartimento di Fisica e Astronomia, Università di Bologna

   INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna

   INFN-Sezione di Bologna

7. Ralf Bender

   Max Planck Institute for Extraterrestrial Physics · Ludwig-Maximilians-Universität München

   Affiliation as printed

   Max Planck Institute for Extraterrestrial Physics

   Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München

8. A. Biviano

   Trieste Astronomical Observatory · Institute for Fundamental Physics of the Universe · National Institute for Astrophysics

   Affiliation as printed

   IFPU, Institute for Fundamental Physics of the Universe

   INAF – Osservatorio Astronomico di Trieste

9. S. Camera

   Istituto Nazionale di Fisica Nucleare, Sezione di Torino · Osservatorio Astrofisico di Torino · University of Turin · National Institute for Astrophysics

   Affiliation as printed

   Dipartimento di Fisica, Università degli Studi di Torino

   INAF – Osservatorio Astrofisico di Torino

   INFN – Sezione di Torino

10. G Cañas-Herrera Aachen Leiden Observatory

    Leiden University · European Space Agency · Leiden Observatory · European Space Research and Technology Centre

    Affiliation as printed

    European Space Agency/ESTEC

    Leiden Observatory, Leiden University

    ESA - Agence Spatiale Européenne = European Space Agency (Agence spatiale européenne (ESA) 8-10, rue Mario Nikis F-75015 Paris - France)

11. G. Castignani

    Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics

    Affiliation as printed

    INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna

12. S. Cavuoti

    Istituto Nazionale di Fisica Nucleare · Astronomical Observatory of Capodimonte · Istituto Nazionale di Fisica Nucleare, Sezione di Napoli · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astronomico di Capodimonte

    INFN section of Naples

13. X. Dupac

    European Space Astronomy Centre

    Affiliation as printed

    ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo

14. S. Dusini

    Istituto Nazionale di Fisica Nucleare · Istituto Nazionale di Fisica Nucleare, Sezione di Padova

    Affiliation as printed

    INFN – Padova

15. S. Escoffier

    Centre National de la Recherche Scientifique · Aix-Marseille Université · Centre de physique des particules de Marseille · Institut National de Physique Nucléaire et de Physique des Particules

    Affiliation as printed

    Aix-Marseille Université, CNRS/IN2P3, CPPM

    CPPM - Centre de Physique des Particules de Marseille (163, avenue de Luminy - Case 902 - 13288 Marseille cedex 09 - France)

16. Maximilian Fabricius

    Max Planck Institute for Extraterrestrial Physics · Ludwig-Maximilians-Universität München

    Affiliation as printed

    Max Planck Institute for Extraterrestrial Physics

    Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München

17. Maria Farina

    Institute for Space Astrophysics and Planetology · National Institute for Astrophysics

    Affiliation as printed

    INAF – Istituto di Astrofisica e Planetologia Spaziali

18. R. Farinelli

    Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics

    Affiliation as printed

    INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna

19. F Faustini

    Astronomical Observatory of Rome · Agenzia Spaziale Italiana · National Institute for Astrophysics

    Affiliation as printed

    INAF-Osservatorio Astronomico di Roma

    Space Science Data Center, Italian Space Agency, via del Politecnico snc

20. S. Ferriol

    Lyon 1 Université · Centre National de la Recherche Scientifique · Institut National de Physique Nucléaire et de Physique des Particules · Institut de Physique des 2 Infinis de Lyon

    Affiliation as printed

    Université Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822

    IP2I Lyon - Institut de Physique des 2 Infinis de Lyon (Campus LyonTech-la Doua Bâtiment Paul DIRAC 4 Rue Enrico Fermi 69622 Villeurbanne Cedex - France)

21. Fabio Finelli

    Istituto Nazionale di Fisica Nucleare, Sezione di Bologna · Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics

    Affiliation as printed

    INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna

    INFN-Bologna

22. N. Fourmanoit

    Centre National de la Recherche Scientifique · Aix-Marseille Université · Centre de physique des particules de Marseille · Institut National de Physique Nucléaire et de Physique des Particules

    Affiliation as printed

    Aix-Marseille Université, CNRS/IN2P3, CPPM

    CPPM - Centre de Physique des Particules de Marseille (163, avenue de Luminy - Case 902 - 13288 Marseille cedex 09 - France)

23. M. Frailis

    Trieste Astronomical Observatory · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astronomico di Trieste

24. Enrico Franceschi

    Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics

    Affiliation as printed

    INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna

25. M. Fumana

    National Institute for Astrophysics

    Affiliation as printed

    INAF-IASF Milano

26. Samuele Galeotta

    Trieste Astronomical Observatory · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astronomico di Trieste

27. Gillis B

    Royal Observatory · University of Edinburgh

    Affiliation as printed

    Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill

28. C. Giocoli

    Istituto Nazionale di Fisica Nucleare, Sezione di Bologna · Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics

    Affiliation as printed

    INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna

    INFN-Sezione di Bologna

29. Javier Graciá-Carpio

    Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Max Planck Institute for Extraterrestrial Physics

30. Frank U. Grupp

    Max Planck Institute for Extraterrestrial Physics · Ludwig-Maximilians-Universität München

    Affiliation as printed

    Max Planck Institute for Extraterrestrial Physics

    Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München

31. S. V. H. Haugan

    University of Oslo

    Affiliation as printed

    Institute of Theoretical Astrophysics, University of Oslo

32. F. Hormuth
    Affiliation as printed

    Felix Hormuth Engineering

33. Allan Hornstrup

    Technical University of Denmark

    Affiliation as printed

    Cosmic Dawn Center (DAWN)

    Technical University of Denmark

34. K. Jahnkę

    Max Planck Institute for Astronomy

    Affiliation as printed

    Max-Planck-Institut für Astronomie

35. Murzban D. Jhabvala

    Goddard Space Flight Center

    Affiliation as printed

    NASA Goddard Space Flight Center

36. Elina Keihänen

    Helsinki Institute of Physics

    Affiliation as printed

    Department of Physics and Helsinki Institute of Physics

37. Smaïn Kermiche

    Centre National de la Recherche Scientifique · Aix-Marseille Université · Centre de physique des particules de Marseille · Institut National de Physique Nucléaire et de Physique des Particules

    Affiliation as printed

    Aix-Marseille Université, CNRS/IN2P3, CPPM

    CPPM - Centre de Physique des Particules de Marseille (163, avenue de Luminy - Case 902 - 13288 Marseille cedex 09 - France)

38. A. Kiessling

    Jet Propulsion Laboratory

    Affiliation as printed

    Jet Propulsion Laboratory, California Institute of Technology

39. R. Kohley

    European Space Astronomy Centre

    Affiliation as printed

    ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo

40. Bogna Kubik

    Lyon 1 Université · Centre National de la Recherche Scientifique · Institut National de Physique Nucléaire et de Physique des Particules · Institut de Physique des 2 Infinis de Lyon

    Affiliation as printed

    Université Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822

    IP2I Lyon - Institut de Physique des 2 Infinis de Lyon (Campus LyonTech-la Doua Bâtiment Paul DIRAC 4 Rue Enrico Fermi 69622 Villeurbanne Cedex - France)

41. Martin Kunz

    University of Geneva

    Affiliation as printed

    Université de Genève, Département de Physique Théorique and Centre for Astroparticle Physics

42. Hannu Kurki-Suonio

    Helsinki Institute of Physics

    Affiliation as printed

    Department of Physics

    Helsinki Institute of Physics

43. Amandine M. C. Le Brun

    Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · Laboratoire d'Étude de l'Univers et des Phénomènes Extrêmes

    Affiliation as printed

    Laboratoire d’etude de l’Univers et des phenomenes eXtremes, Observatoire de Paris, Université PSL, Sorbonne Université, CNRS

    LUX - Laboratoire d’étude de l’Univers et des phénomènes eXtrèmes (Site de Meudon : 5, place Jules Janssen 92195 MEUDON. Site de Paris : 61, av. de l’Observatoire 75014 PARIS. - France)

44. S. Ligori

    Osservatorio Astrofisico di Torino · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astrofisico di Torino

45. Per Barth Lilje

    University of Oslo

    Affiliation as printed

    Institute of Theoretical Astrophysics, University of Oslo

46. V. Lindholm

    Helsinki Institute of Physics

    Affiliation as printed

    Department of Physics

    Helsinki Institute of Physics

47. Ivan Lloro

    SKA Observatory

    Affiliation as printed

    SKAO, Jodrell Bank, Lower Withington

48. Gabriele Mainetti

    Centre National de la Recherche Scientifique · Institut National de Physique Nucléaire et de Physique des Particules · Centre de Calcul de l’Institut National de Physique Nucléaire et de Physique des Particules

    Affiliation as printed

    Centre de Calcul de l’IN2P3/CNRS

    CC-IN2P3 - Centre de Calcul de l'IN2P3 (Domaine scientifique de La Doua 43 bd du 11 Novembre 1918 69622 Villeurbanne Cedex - France)

49. O. Mansutti

    Trieste Astronomical Observatory · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astronomico di Trieste

50. O. Marggraf

    University of Bonn

    Affiliation as printed

    Universität Bonn, Argelander-Institut für Astronomie

51. N. Martinet

    Centre National de la Recherche Scientifique · Aix-Marseille Université · Laboratoire d’Astrophysique de Marseille

    Affiliation as printed

    Aix-Marseille Université, CNRS, CNES, LAM

    LAM - Laboratoire d'Astrophysique de Marseille (Pôle de l'Étoile Site de Château-Gombert 38, rue Frédéric Joliot-Curie 13388 Marseille cedex 13 - France)

52. R. Massey

    Durham University

    Affiliation as printed

    Department of Physics, Institute for Computational Cosmology, Durham University

53. Eduardo Medinaceli

    Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics

    Affiliation as printed

    INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna

54. S. Mei

    Centre National de la Recherche Scientifique · Université Paris Cité · Institut National de Physique Nucléaire et de Physique des Particules · Université Paris Diderot · Centre Pierre Binétruy · University of California, Berkeley

    Affiliation as printed

    CNRS-UCB International Research Laboratory, Centre Pierre Binétruy, IRL2007, CPB-IN2P3

    Université Paris Cité, CNRS, Astroparticule et Cosmologie

    APC (UMR_7164) - AstroParticule et Cosmologie (APC - UMR 7164, Université Paris Diderot, 10 rue Alice Domon et Léonie Duquet, case postale 7020, F-75205 Paris Cedex 13 - France)

    CPB - Centre Pierre Binétruy (UNIVERSITY OF CALIFORNIA BERKELEY - Berkeley, Physics Department 00366 LeConte Hall - United States)

55. Y. Mellier

    Centre National de la Recherche Scientifique · Institut d'Astrophysique de Paris · Sorbonne Université

    Affiliation as printed

    Institut d’Astrophysique de Paris

    Institut d’Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Université

    IAP - Institut d'Astrophysique de Paris (98bis, bd Arago - 75014 Paris France - France)