Ariel
Ariel is a space telescope designed to systematically survey the atmospheres of a thousand extrasolar planets—ranging from gas giants to rocky planets, both hot and temperate—orbiting various stellar types. ARIEL will measure the composition and structure of planetary atmospheres, constrain the nature of planetary cores, detect the presence of clouds, and study interactions with the host star.
The role of IAS
Beginning in 2015, drawing on accumulated expertise, teams from five French laboratories (IAP, DAp/AIM, IAS, LESIA, LAB) played a major role in Ariel's preliminary studies. Their contributions to the scientific proposal, mission scenario, and feasibility studies for the infrared spectrometer at the heart of the satellite were decisive. This led the French teams to assume responsibility for the design and delivery of the infrared spectrometer. The instrument will be built under CNES supervision by CEA-Irfu, with significant contributions from the IAS and LESIA.
“Ariel is the logical continuation of the exoplanet observation programs we will conduct with the JWST. Ariel's statistical approach is crucial; it is highly gratifying that Europe can play a leading role in this new chapter of exoplanet research,” concludes Pierre-Olivier Lagage.
“ARIEL is the key to deciphering the atmospheric properties of other worlds!”
Status
Under development
Partners (academic / industrial)
Funding agencies
Key dates (est.)
Key milestones
Launch: May 2028
Contacts
Scientific and Technical Contacts
- Marc Ollivier, Solar System and Planetary Systems Physics Team at IAS (CNRS / Université Paris-Saclay)
- Jean-Philippe Beaulieu, Institut d’Astrophysique de Paris
- Pierre-Olivier Lagage, Department of Astrophysics at CEA-Irfu, UMR AIM Paris-Saclay
- Pierre Drossart, LESIA, Observatoire de Paris, CNRS, PSL, Sorbonne Université, Université Paris-Diderot
The selection of the space mission
The Programme Committee of the European Space Agency has selected the Ariel mission as the 4th medium-class mission (€450 million budget) of the "Cosmic Vision" programme.
Ariel will be launched from the Kourou spaceport in French Guiana in May 2028 and placed into orbit at the Lagrange point L2, located 1.5 million kilometres from Earth. Ariel is a space telescope designed to systematically survey the atmospheres of a thousand extrasolar planets—ranging from gas giants to rocky planets, whether hot or temperate—orbiting various types of stars.
Ariel will measure the composition and structure of planetary atmospheres, constrain the nature of planetary cores, detect the presence of clouds, and study interactions with the host star.
The selection process took place in several stages:
Call for mission proposals issued by ESA in August 2014;
Pre-selection in June 2015 of 3 missions out of the 27 proposed for detailed concept studies;
Evaluation of the study results by an expert committee and recommendation of a mission in November 2017;
Formal vote by the ESA Programme Committee and public announcement on 20 March 2018.
Pierre Drossart points out: “The study of the ARIEL mission was based on the EChO project, a candidate for ESA's M3 mission in 2014. Advances in exoplanet research now clearly establish spectroscopy as a key focus for the coming decade in the study of their atmospheres.”
The Ariel mission was proposed by a consortium of over 60 institutes across 15 European countries(*). Scientific and technical coordination is led by the United Kingdom. A contribution from the United States is currently under review.
Ariel will feature a telescope with a primary mirror of approximately one metre in diameter to collect visible and infrared light from stars orbited by an exoplanet. A spectrometer will disperse this light into a "rainbow," and as the exoplanet transits in front of its star, the resulting spectrum will reveal absorption bands corresponding to the stellar light filtered by molecules in the exoplanet's atmosphere.
Marc Ollivier emphasises: “This observation is particularly delicate, as information about the planet must be isolated from the light of the star itself, which is 1,000 to 100,000 times brighter than the planet. Ultimate performance is achieved through the instrument's intrinsic photometric stability and a rigorous understanding of its operation.”
Ariel builds upon research conducted over the past decade. In 2007, water vapour, followed by carbon dioxide and carbon monoxide, was detected in the atmosphere of the hot Jupiter HD189733b using the Spitzer and Hubble space telescopes. These initial results highlighted the difficulty of the measurements and the immense diversity of exoplanetary atmospheres. Obtaining such challenging measurements across a large number of planets requires dedicated and optimised instruments. Consequently, a group of scientists initiated studies as early as 2008.
Artist's impression of the Ariel satellite en route to its final destination: in orbit around the Lagrange point L2.
ESA/STFC RAL Space/UCL/Europlanet-Science Office
Ariel will be placed into orbit around the Lagrange point L2, 1.5 million kilometres from Earth. It will orbit the Sun synchronously with the Earth.
ESA/STFC RAL Space/UCL/Europlanet-Science Office