---
title: "CHEOPS"
chunk: 2/2
source: "https://en.wikipedia.org/wiki/CHEOPS"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T12:43:30.971166+00:00"
instance: "kb-cron"
---

== Priorities ==
Eighty per cent of the science observing time on CHEOPS is dedicated to the CHEOPS Guaranteed Time Observing (GTO) Programme, under the responsibility of the CHEOPS Science Team chaired by Didier Queloz. The majority of the GTO programme involves the characterization of known transiting exoplanets and improvement of known parameters. Part of the GTO programme is to find transits of known exoplanets that were confirmed by other techniques, such as radial-velocity, but not by the transit-method. Another part of the GTO programme includes exploration of multi-systems and search of additional planets in those systems, for example using the transit-timing-variation (TTV) method.
The other 20% of the science observing time on CHEOPS is made available to the scientific community in the form of an ESA-run Guest Observers' (GO) Programme. Researchers can submit proposals for observations with CHEOPS through an annual Announcements of Opportunity (AO) Program. The approved AO-1 projects include observations of the Hot Jupiters HD 17156 b, Kelt-22A b, warm jupiter K2-139b, multi systems GJ 9827, K2-138, the exoplanet DS Tuc Ab, 55 Cancri e, WASP-189 b and other exoplanet science related observations, such as planets around rapidly-rotating stars, planet material around white dwarfs and searching for transiting exocomets around 5 Vulpeculae.

== Timeline ==

=== Prior to launch ===
Organized as a partnership between the European Space Agency (ESA) and the Swiss Space Office, CHEOPS was selected in October 2012 from among 26 proposals as the first S-class ("small") space mission in ESA's Cosmic Vision programme. ESA is the mission architect and responsible for the spacecraft and launch opportunity procurement. The project is led by the Center for Space and Habitability at the University of Bern, Switzerland, with contributions from other Swiss and European universities. The principal investigator for the science instrument is Willy Benz at the University of Bern and the principal scientist from ESA is Kate Isaak. After a competition phase, Airbus Defence and Space in Spain was selected as the spacecraft builder. The ESA mission cost is capped at €50 million. Media Lario S.r.l. (Italy) was responsible for the optical finishing of the primary optical element.

=== Launch ===
CHEOPS launched on board of a Soyuz-STA launch vehicle on 18 December 2019, at 08:54:20 UTC from Centre Spatial Guyanais (CSG) in Kourou, French Guiana. CHEOPS separated after two hours and 23 minutes from lift-off. The primary payload was the first satellite of ASI's COSMO-SkyMed Second Generation constellation, CSG 1. The launcher also deployed three CubeSats, including ESA's OPS-SAT. CHEOPS went into a 712 km (442 mi) altitude Sun-synchronous polar orbit.

=== First light ===
After the cover of the telescope was opened on 29 January 2020, CHEOPS took its first light image on 7 February 2020. The image is centred on the star HD 70843, a yellow-white star located around 150 light years away. The star was selected because of its brightness and position on the sky. The stars in the image are blurry, which is intended. The defocused mirror distributes the light of the star over many pixels of the detector, making the measurements of starlight more precise. The first light images were better than it was expected from tests in the laboratory. The images were smoother and more symmetrical, which could reduce noise caused by the detector and the spacecraft. In April 2020, the telescope began science operations.

=== Results ===
In 2020, a study of WASP-189b (a 'hot Jupiter') has been published
In 2021, TOI-178 has been found to have 6 planets, 5 having orbital resonances. Planetary densities have been calculated
In 2021, CHEOPS supplemented by TESS data characterized AU Mic and its planet b. It also confirmed transit-timing variations, caused by the outer planets
In 2022, HD 108236 f was discovered with CHEOPS
TOI-561 is a multi-planet system that was studied with CHEOPS, HARPS-N, and TESS. A study published in 2022 has shown that TOI-561 b is the lowest density ultra-short period planet known so far
In 2023, CHEOPS observed occultations caused by the planet 55 Cancri e and was able to observe individual occultations for the first time
A study searching for transits around 6 white dwarfs did not detect any transits and a study to search for exomoons around v2 Lupi d was unable to detect any additional transits. The full transit of v2 Lupi d was observed for the first time with CHEOPS, potentially aiding any future searches for exomoons around this planet
In February 2026, using CHEOPS observations, scientists described a unique configuration of a planetary system around the star LHS 1903, where the innermost and outermost planets are rocky, while the two middle planets have extended atmospheres. This provided support for the inside-out model of planet formation.

== See also ==
List of European Space Agency programmes and missions
List of exoplanet search projects
List of space telescopes
CoRoT – European space telescope that operated between 2006 - 2014
Kepler space telescope – NASA space telescope for exoplanetology (2009–2018)
MOST – Canada's first space telescopePages displaying short descriptions of redirect targets
PLATO – European space telescope to detect exoplanets
TESS – NASA satellite of the Explorer program

== References ==

== External links ==

CHEOPS ESA homepage
CHEOPS homepage includes orbital tracking of the CHEOPS spacecraft
CHEOPS mission visualization – video
Orbital Tracking at uphere.space