CEAS Space Journal

, Volume 9, Issue 4, pp 379–398 | Cite as

An afocal telescope configuration for the ESA ARIEL mission

  • Vania Da DeppoEmail author
  • Mauro Focardi
  • Kevin Middleton
  • Gianluca Morgante
  • Enzo Pascale
  • Samuele Grella
  • Emanuele Pace
  • Riccardo Claudi
  • Jérôme Amiaux
  • Josep Colomé Ferrer
  • Thomas Hunt
  • Miroslaw Rataj
  • Carles Sierra-Roig
  • Iacopo Ficai Veltroni
  • Paul Eccleston
  • Giuseppina Micela
  • Giovanna Tinetti
Original Paper


Atmospheric Remote-Sensing Infrared Exoplanet Large Survey (ARIEL) is a candidate as an M4 ESA mission to launch in 2026. During its 3.5 years of scientific operations, ARIEL will observe spectroscopically in the infrared (IR) a large population of known transiting planets in the neighbourhood of the solar system. ARIEL aims to give a breakthrough in the observation of exoplanet atmospheres and understanding of the physics and chemistry of these far-away worlds. ARIEL is based on a 1 m class telescope feeding a collimated beam into two separate instrument modules: a spectrometer module covering the waveband between 1.95 and 7.8 μm and a combined fine guidance system/visible photometer/NIR spectrometer. The telescope configuration is a classic Cassegrain layout used with an eccentric pupil and coupled to a tertiary off-axis paraboloidal mirror. To constrain the thermo-mechanically induced optical aberrations, the primary mirror (M1) temperature will be monitored and finely tuned using an active thermal control system based on thermistors and heaters. They will be switched on and off to maintain the M1 temperature within ± 1 K by the telescope control unit (TCU). The TCU is a payload electronics subsystem also responsible for the thermal control of the spectrometer module detectors as well as the secondary mirror mechanism and IR calibration source management. The TCU, being a slave subsystem of the instrument control unit, will collect the housekeeping data from the monitored subsystems and will forward them to the master unit. The latter will run the application software, devoted to the main spectrometer management and to the scientific data on-board processing.


Space instrumentation Telescope Optical design Exoplanetary science Active thermal control ICU 



This activity has been realized under the Agenzia Spaziale Italiana (ASI) contract to the Istituto Nazionale di Astrofisica (INAF) (ARIEL 2015-038-R.0). The support from the ESA ARIEL Study Team is gratefully acknowledged.


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Copyright information

© CEAS 2017

Authors and Affiliations

  • Vania Da Deppo
    • 1
    • 2
    Email author
  • Mauro Focardi
    • 3
  • Kevin Middleton
    • 4
  • Gianluca Morgante
    • 5
  • Enzo Pascale
    • 6
    • 7
  • Samuele Grella
    • 8
  • Emanuele Pace
    • 9
  • Riccardo Claudi
    • 2
  • Jérôme Amiaux
    • 10
  • Josep Colomé Ferrer
    • 11
  • Thomas Hunt
    • 12
  • Miroslaw Rataj
    • 13
  • Carles Sierra-Roig
    • 11
  • Iacopo Ficai Veltroni
    • 8
  • Paul Eccleston
    • 4
  • Giuseppina Micela
    • 14
  • Giovanna Tinetti
    • 15
  1. 1.CNR-IFN PadovaPaduaItaly
  2. 2.INAF-Osservatorio Astronomico di PadovaPaduaItaly
  3. 3.INAF-Osservatorio Astrofisico di ArcetriFlorenceItaly
  4. 4.RAL Space-STFC Rutherford Appleton LaboratoryDidcotUK
  5. 5.INAF-IASF BolognaBolognaItaly
  6. 6.Dipartimento di Fisica-Università degli Studi di Roma “La Sapienza”RomeItaly
  7. 7.School of Physics and AstronomyCardiff UniversityCardiffUK
  8. 8.Leonardo S.p.ACampi BisenzioItaly
  9. 9.Dipartimento di Fisica ed Astronomia-Università degli Studi di FirenzeFlorenceItaly
  10. 10.Laboratoire Léon BrillouinUMR12 CEA-CNRS SaclayGif sur YvetteFrance
  11. 11.Institut de Ciències de l’Espai (CSIC-IEEC)BellaterraSpain
  12. 12.Mullard Space Science LaboratoryHolmbury St. MarySurreyUK
  13. 13.Space Research CentrePolish Academy of SciencesWarsawPoland
  14. 14.INAF-Osservatorio Astronomico di PalermoPalermoItaly
  15. 15.Department of Physics and AstronomyUniversity College LondonLondonUK

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