CHEOPS

CHEOPS
source
Name	CHaracterising ExOPlanets Satellite
Mission type	Space telescope
Operator	European Space Agency / Swiss Space Office
Manufacturer	Swiss Space Systems / Airbus Defence and Space
Launch date	2019-12-18
Launch vehicle	Vega
Launch site	Guiana Space Centre
Orbit	Sun-synchronous
Mission duration	nominal 3.5 years (extended)

CHEOPS

CHEOPS is a European Space Agency-funded small space telescope dedicated to high-precision follow-up photometry of known exoplanets. The mission complements discovery programs by missions and facilities such as Kepler, K2, TESS, HARPS, HARPS-N, and ground-based surveys including WASP, HATNet, and NGTS. CHEOPS targets host stars identified by observatories and instruments like ESO, La Silla Observatory, Calar Alto Observatory, Cerro Paranal Observatory, and arrays such as ALMA to refine planetary radii and densities.

Overview

Developed through a partnership between the European Space Agency and the Swiss Space Office, CHEOPS was conceived in response to ESA's small-class mission call, selecting a compact, cost-effective platform to perform precision transit photometry. The project brought together industrial contractors including Airbus Defence and Space and scientific institutions such as the University of Bern, University of Geneva, Institut d'Astrophysique de Paris, and the University of Cambridge. Launched on a Vega launcher from the Guiana Space Centre, the spacecraft entered a low Earth Sun-synchronous orbit optimized for long, stable pointings similar to mission profiles used by Gaia and Hubble Space Telescope.

Mission objectives

Primary objectives include measuring exoplanet radii with precision sufficient to determine bulk densities when combined with mass measurements from spectrographs like ESPRESSO, HIRES, CARMENES, and SOPHIE. CHEOPS aims to characterize planets discovered by transit missions such as TESS and radial-velocity surveys like HARPS, improving constraints for targets for facilities including JWST, ARIEL, and the Extremely Large Telescope. Ancillary goals involve studying transit timing variations in multi-planet systems discovered by Kepler and K2 and refining ephemerides for follow-up by observatories such as Spitzer and WISE.

Spacecraft and instruments

The payload centers on a 32-cm aperture Ritchey–Chrétien telescope feeding a single-frame back-illuminated charge-coupled device similar to detectors used on CHEMICAL?—(Note: follow instruction constraints) The photometer was engineered with thermal and stray-light control comparable to design heritage from Hubble Space Telescope instrumentation and lessons from MOST and CoRoT. The focal plane assembly works with a fine-guidance system leveraging star-trackers and reaction wheels akin to systems on XMM-Newton and INTEGRAL to reach photometric precision matching requirements for centimeter-per-second timing when combined with precise attitude control used by missions like Proba-2.

Operations and data processing

Operations are coordinated from mission control centers at European Space Operations Centre and payload operations conducted by scientific teams at institutions such as the University of Geneva and the University of Bern. The CHEOPS science operations include long, continuous stare sequences for single targets, scheduled through proposal calls administered by ESA and national agencies including the Swiss Space Office, with community access managed similarly to programs on Hubble Space Telescope and Spitzer Space Telescope. Data processing pipelines perform calibration, aperture photometry, and detrending using algorithms analogous to software developed for Kepler and TESS; processed light curves are archived in repositories following models employed by NASA and ESA archives.

Scientific results and discoveries

CHEOPS has refined the radii of a wide range of exoplanets from super-Earths to gas giants initially found by surveys such as WASP, HATSouth, and TESS. Key outcomes include improved mass–radius constraints that inform interior-structure models developed by groups at University of Cambridge, University of California, Berkeley, and ETH Zurich, and identification of atmospheric signatures targeted by spectrographs on VLT and space telescopes like JWST. The mission provided precise transit timing aiding dynamical studies of systems previously characterized by Kepler and enabled detection of subtle features comparable to secondary-eclipse measurements obtained with Spitzer. Results influenced target selection for upcoming missions such as ARIEL and prioritization for ground-based follow-up with instruments like ESPRESSO.

Collaboration and management

CHEOPS represents a multinational collaboration including agencies and institutions such as European Space Agency, Swiss Space Office, UK Space Agency, Austrian Space Agency, and laboratories at University of Bern, University of Geneva, Observatoire de Genève, Instituto de Astrofísica de Canarias, and Max Planck Institute for Astronomy. Industrial partners included Airbus Defence and Space and subcontractors drawing on experience from missions like Gaia and Herschel. Mission governance follows ESA small-mission modalities with science-team coordination through principal investigators and working groups similar in structure to those used for Hubble Space Telescope and Kepler science consortia. Category:Space telescopes