Ariel exoplanet survey mission greenlit by ESA

ESA’s space-based Ariel mission, which will survey around 1,000 planets beyond our solar system, has been formally adopted by the agency.

Scheduled to launch in 2029, Ariel will be the first mission that will study the chemical composition and thermal atmospheric properties of exoplanets as they transit distant stars. These measurements will be observed using a one-metre class cryogenic telescope that will operate at temperatures of 35-40 Kelvin (-238 to -233 Celsius), collecting visible and infrared light. An onboard guidance system will allow the telescope to focus on exoplanets with high precision, while a photometer and spectrometer will help detect the presence of clouds as well as the chemicals in the planets’ atmospheres.

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“Ariel will enable planetary science far beyond the boundaries of our own Solar System,” said Günther Hasinger, ESA’s Director of Science. “The adoption of Ariel cements ESA’s commitment to exoplanet research and will ensure European astronomers are at the forefront of this revolutionary field for the next decade and well beyond.”

(Credit: ESA/ATG medialab)

The spacecraft’s payload has been in development for the past five years under the Ariel Mission Consortium, which consists of more than 50 institutes from across 17 different countries. UK involvement in the project is strong, with contributions from University College London, the Science and Technology Facilities Council’s (STFC) RAL Space, Technology Department and UK Astronomy Technology Centre, Cardiff University and Oxford University.

“This represents the culmination of lots of preparatory work by our teams across the world over the last five years in order to demonstrate the feasibility and readiness of the payload,” said Ariel Consortium project manager, Paul Eccleston, from STFC RAL Space.

“We now go full speed ahead to fully develop the design and start building prototypes of the instrumentation on the spacecraft.”

Ariel will operate from the L2 Lagrange Point (Credit: ESA/STFC RAL Space/UCL/Europlanet-Science Office)

Ariel is planned to launch from ESA’s spaceport in Kourou, French Guiana on board ESA’s new Ariane 6 rocket, which is expected to debut in 2022. The spacecraft will then be placed in orbit around the Lagrange Point 2 (L2), the gravitational balance point in line with the Earth and the Sun, but 1.5 million km further out than Earth’s orbit. L2 is not only stable, but also uses the Earth to shield much of the Sun’s light, essential for accurate measurement of faraway planets. The UK-led Comet Interceptor mission, which The Engineer wrote about in detail last year, will hitch a ride on the Ariane 6 rocket as the Fast Class mission that will accompany Ariel.  The industrial contractor for the spacecraft bus that will carry both missions is due to be selected in summer 2021. ​