Planet Hunters: ESA’s New and Future Exoplanet Missions

Searching for exoplanetary systems. Credit: ESA–C. Carreau

ESA’s trifecta of dedicated exoplanet missions – Cheops, Plato, and Ariel – will also be complemented with the upcoming James Webb Space Telescope mission.

ESA’s new and future exoplanet missions. ESA’s trifecta of dedicated exoplanet missions – Cheops, Plato, and Ariel – will also be complemented with the upcoming James Webb Space Telescope mission. Credit: ESA

The Characterising Exoplanet Satellite, Cheops, was launched in December 2019 and is observing bright stars known to host exoplanets, in particular Earth-to-Neptune-sized planets. It is recording the precise sizes of these relatively small planets and combined with mass measurements already calculated from other observatories, will enable the planet’s density to be determined, and thus make a first-step characterization of the nature of these worlds. Cheops will also identify candidates for additional study by future missions. For example, it will provide well-characterized targets for the international James Webb Space Telescope launching in December 2021, which will perform further detailed studies of their atmospheres.

Artist’s impression of CHEOPS. Credit: © ESA / ATG medialab

Plato, the PLAnetary Transits and Oscillations of stars mission, is a next-generation planet hunter with an emphasis on the properties of rocky planets in orbits up to the habitable zone around Sun-like stars – the location from a star where liquid water can exist on the planet’s surface. Importantly, it will also analyze the planet’s host star, including its age, and thus give insight into the evolutionary state of the entire extrasolar system.

This artist’s concept shows the European Space Agency’s ARIEL spacecraft on its way to Lagrange Point 2 (L2) — a gravitationally stable, Sun-centric orbit — where it will be shielded from the Sun and have a clear view of the sky. NASA’s JPL will manage the mission’s CASE instrument. Credit: ESA/STFC RAL Space/UCL/Europlanet-Science Office

Ariel, the Atmospheric Remote-Sensing Infrared Exoplanet Large-survey mission, will perform a chemical census of a large and diverse sample of exoplanets by analyzing their atmospheres in great detail, finally answering still open questions like: What are exoplanets made of, how do planets and planetary systems form, and how do planets and their atmospheres evolve?

With the complementary work of both ground- and space-based observatories, we will get closer to understanding one of humanity’s biggest questions: are we alone in the Universe?