CHEOPS in a nutshell

Science

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

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)

Programmatics 

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.

Instrument

Design

• 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)

Spacecraft

Design

• 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

Organisation

• 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

Opportunities

Guest Observing

• 30% 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