UK part of ARIEL exoplanet project selected as ESA's next medium-class science mission

20 March 2018


ARIEL, a mission to answer fundamental questions about how planetary systems form and evolve, has been selected by the European Space Agency (ESA) as its next medium-class science mission, due for launch in 2026. STFC through its RAL Space and UK ATC teams is part of the UK team contributing to this project.

During a 4-year mission, ARIEL will observe 1000 planets orbiting distant stars and make the first large-scale survey of the chemistry of exoplanet atmospheres. ESA’s Science Programme Committee announced the selection of ARIEL from three candidate missions on 20 March 2018.

The ARIEL Consortium Project Manager, Paul Eccleston, of STFC RAL Space said “It is wonderful news that ESA have selected ARIEL for the next medium class science mission. The team are very excited to have the opportunity to realise the mission we’ve been developing for the last two years. ARIEL will revolutionise our understanding of how planetary systems form and evolve, helping us put our own solar system into context and compare it to our neighbours in the galaxy.”

The ARIEL mission has been developed by a consortium of more than 60 institutes from 15 ESA member state countries, including UK, France, Italy, Poland, Spain, the Netherlands, Belgium, Austria, Denmark, Ireland, Hungary, Sweden, Czech Republic, Germany, Portugal, with an additional contribution from NASA in the USA currently under study. UK institutions have provided the leadership and planning for ARIEL, including UCL, STFC RAL Space, STFC UK ATC, Cardiff University and the University of Oxford.

Ian Bryson, Head of Strategic Development at STFC’s UK Astronomy Technology Centre said, “It is always exciting to be part of an ESA Science Mission and ARIEL is no exception as it will discover key information about the nature and atmospheric composition of some of the thousands of exoplanets we already know to exist. At the UK ATC we have been working on ARIEL (and the predecessor concept EChO) since 2011 and look forward to getting stuck into the next design phase.”

ARIEL will study a diverse population of exoplanets ranging from Jupiter- and Neptune-size planets down to super-Earths, in a wide variety of environments. While some of the planets may be in the habitable zones of their stars, the main focus of the mission will be on warm and hot planets in orbits close to their star.

Warm and hot exoplanets represent a natural laboratory in which to study the chemistry and formation of planets. High temperatures keep different molecular species circulating throughout the atmosphere and prevent them from sinking or forming cloud layers, where they can become hidden from remote detection. The scorching temperatures experienced by planets close to their stars, which can be at temperatures in excess of 2000 degrees Celsius, also mean that more molecules from the planet’s interior make their way into the atmosphere. This provides ARIEL with better information about the planet’s internal composition and the formation history of the planetary system.

ARIEL’s Principal Investigator, Prof Giovanna Tinetti of UCL said, “Although we’ve now discovered around 3800 planets orbiting other stars, the nature of these exoplanets remains largely mysterious. ARIEL will study a statistically large sample of exoplanets to give us a truly representative picture of what these planets are like. This will enable us to answer questions about how the chemistry of a planet links to the environment in which it forms, and how its birth and evolution are affected by its parent star.”

ARIEL will have a meter-class telescope primary mirror to collect visible and infrared light from distant star systems. A spectrometer will spread the light into a ‘rainbow’ and extract the chemical fingerprints of gases in the planets’ atmospheres, which become embedded in starlight when a planet passes in front or behind the star. A photometer and guidance system will capture information on the presence on clouds in the atmospheres of the exoplanets and will allow the spacecraft to point to the target star with high stability and precision.

The payload for ARIEL will be amongst the first to be assembled and tested at the STFC RAL Space National Satellite Test Facility, due to be open in mid-2020 following a £99 million investment as part of the UK Government’s Industrial Strategy Challenge Fund.

ARIEL will be launched from Kourou in French Guiana and will be placed in orbit around the Lagrange Point 2 (L2), a gravitational balance point 1.5 million kilometres beyond the Earth’s orbit around the Sun. Here, the spacecraft is shielded from the Sun and has a clear view of the whole sky to maximise the possible target exoplanets for observations.

Dr Chris Mutlow, Director of STFC RAL Space said, “Congratulations to the whole European consortium for ARIEL. It is great to see strong UK involvement including three STFC departments contributing their expertise and support for the European science community. It is particularly exciting for RAL Space as we will conduct some of the tests in the National Satellite Test Facility, which will be ready in time for this mission.”

ARIEL (Atmospheric Remote-Sensing Infrared Exoplanet Large-survey) Facts and Figures

Elliptical primary mirror: 1.1 x 0.7 metres
Instrumentation: 3 photometric channels and 3 low resolution spectrometers covering from 0.5 to 7.8 microns in wavelength
Mission lifetime: 4 years in orbit
Launch date: 2028
Payload mass: ~450 kg
Total Spacecraft Dry mass: ~1200 kg
Launch mass: ~1300kg
Destination: Sun – Earth Lagrange Point 2 (L2)
ESA Mission Cost: ~450 million Euros, plus nationally funded contribution of the payload
Launch vehicle: Ariane 6-2 from French Guiana

Please visit the website for more information on ARIEL.

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Press Officer STFC

Notes for Editors

STFC RAL Space
RAL Space, based at STFC's Rutherford Appleton Laboratory, carries out an exciting range of world-class space research and technology development. It has had significant involvement in over 200 space missions and is at the forefront of UK Space Research.
Follow us on Twitter @RAL_Space_STFC.

UKATC
Based at the Royal Observatory in Edinburgh and operated by STFC, the UK Astronomy Technology Centre (UK ATC) is the national centre for astronomical technology. The UK ATC designs and builds instruments for many of the world’s major telescopes. It also project manages UK and international collaborations and its scientists carry out observational and theoretical research into questions such as the origins of planets and galaxies. The UK ATC has been at the forefront of previous key initiatives at the VLT, including the construction of KMOS (K-band Multi-Object Spectrograph) which enables 24 objects to be observed simultaneously in infrared light.

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