CHEOPS in a nutshell

Below is a concise summary of the key features of CHEOPS.
A fact sheet on CHEOPS, aimed at potential users of the satellite, can be downloaded from here.


Top-level Objectives

  • First-step characterisation of super-Earths and Neptunes
  • Insight into physics and formation of planets; identification of planets with atmospheres; constraints on planet migration
  • Identification of golden targets for spectroscopic characterisation
  • Probing atmospheres of hot-Jupiters (phase curve measurements), study of physical mechanisms and efficiency of energy transport


  Spacecraft Rendering    


Key Science Requirements


  • Photometric precision (stability) over 48 hr timescale: 20 ppm (6 hrs) for G-type star, 6≤ V≤9; 85ppm (3 hrs) for K-type star, V ≤12
  • Sky coverage, target observability/visibility
  • Temporal resolution  (1 measurement/min; timing precision (1s))
  •  Mission lifetime of 3.5 years (5 years goal)




Mission Flavour and Partners


  • S (small)-class mission in ESA’s Science Cosmic Vision Programme in partnership with Switzerland, with important contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden and the United Kingdom






  • Single high accuracy photometer, VIS/NIR range (0.35-1.1 um)
  • Compact Ritchey-Chrétien telescope, physical diameter = 320 mm (equivalent diamaneter 300 mm)
  • 60 kg / 60 W / 1.2 Gbits per day.
  • Single, frame-transfer, back-illuminated and back-thinned CCD (AIMO), 1k x 1k pixels, op. temp -40 deg C (stabilised to 10mK).
  • Baffle to meet stringent stray-light requirement.
  • Developed by a consortium led by the University of Bern (CH).






  • Recurring design based on AS-250 (~1 m3, ~ 290 kg, ~ 200 W).
  •  3-axes stabilised, APE < 4 arcsec (rms).
  • Roll around Line of Sight (LoS) to maintain radiators pointing to cold space.
  • LoS within 60 deg half-cone around anti-Sun direction.
  • Developed by Airbus D & S Spain.


Ground Segment



  • Mission Operations Centre (MOC) development by GMV (ES); operations at Torrejon de Ardoz by INTA (ES).
  • Science Operations Centre (SOC) at University of Geneva (CH).
  • Ground stations at Torrejon, Villafranca and Kiruna (LEOP only).
  • All operations incl. Launch and Early Orbit Phase and commissioning executed from MOC.
  • Mission Planning System under SOC responsibility.



Observing Opportunities with CHEOPS

Guest Observing


  • 20% of total observing time available to the Science Community through ESA's Guest Observers Programme which is made up of two components:
    • Annual announcements of opportunuty (AO) - the first AO, AO-1,  opened and closed on 19 March 2019 and 6 May 2019 respectively, with AO-2 opening/closing on 4 November/1 Decembet 2020. AO-3 is forseen to open in early November 2021.
    • A Discretionary Programme which is open all year round. 


Launch and Orbit


  • Launched from Kourou on Soyuz rocket operated by Arianespace, co-passenger under ASAP-S.
  • Launch date/time: 18 December 2019 at 05:54 local time (08:54GMT/UTC).
  • Sun-synchronous orbit, Local Time of the Ascending Node 6am, altitude of 700 km.