A telescope to study the atmospheres of planets outside our solar system launched by the European Space Agency in the late 2020s.
The mission, which was named Ariel, was selected by the Organization's Science Committee on Tuesday.
The project is scientifically led by astrophysicist Giovanna Tinetti at University College London, UK.
"In the next decade, we will discover many, many planets ̵
"All of this is amazing, but we want to go beyond it and begin to understand the nature of these planets, how they formed, how they evolved, and ultimately brought our solar system to the forefront," said the lead researcher to BBC News.
Ariel will use a meter-long mirror and instrumentation designed to analyze in visible and infrared light the chemical composition of the gases surrounding distant worlds, or exoplanets, as they are known.
This information should provide insights on how certain types of planets form around certain stars.
Prof. Tinetti explained, "We want many planets – some that are as small as Earth or very large as Jupiter – and at different temperatures – extremely hot, warm or temperate – to survey very different types of stars. " We want try all the extremes and the more normal cases, because what we're trying to understand is the & # 39; standard model & # 39; for planets, if such a model even exists. "
Ariel (Atmospheric remote-singing infrared exoplanet large-survey)
Ariel is the latest addition to Esa's mid-range portfolio. To win the launch opportunity in 2028, the proposal had to surpass competition from an X-ray telescope (Xipe) and a mission to study energetic particles around the Earth (Thor).
A detailed technical assessment will now be carried out before the Ariel project is formally "accepted" – Esa legal-speech for "final go-ahead". This release, which should take place over the next two years, paves the way for the manufacture of the flight hardware.
Ariel is the third exoplanet project selected by Esa in recent years.
Already a small telescope called Cheops is coming, which should go up next year to better measure the size of these distant worlds; and 2026 is followed by Plato, a telescope that seeks to find "true earths" – planets as big as our homeworld, orbiting at the same distance from sun-like stars.
And Americans too have their dedicated planet hunters, with the latest, the Transit Exoplanet Survey Satellite (Tess), which will launch in the coming weeks.
But at some point, the science of exoplanets must go beyond merely finding and counting objects; Their chemical compositions and physical conditions must be determined.
The telescope that will intervene in this problem is the James Webb Observatory, Hubble's successor.
The next year, it will be in orbit and, with its 6.5m diameter mirror, examine the planet's atmosphere in exquisite detail. But the mission led by the US Space Agency is likely to see only 150-200 exoplanets in their first five years of operation because of all the other demands of their time from astronomers.
Ariel, on the other hand, will have the only quest to characterize 500-1,000 planets in orbit during the early years.
And one aspect that would benefit Ariel is the lack of any moving parts in his structure, commented Plato team member Dr. Ing. Don Pollaco of Warwick University, UK.
"The problem with all of these planetary experiments is that the signals you're looking for are so incredibly small that every scheme in the instrument itself dominates the signal," he explained.
"And the system is often associated with bits that move, so the great thing about Ariel is that it's a fixed format – nothing changes," he told BBC News.
Ariel is expected to cost Esa around 460 million euros for the spacecraft chassis, launcher and operation. As is customary for such science missions, the individual Member States charge the Agency for the scientific payload.
Britain will take over the technical direction of the project, and the instrumentation will therefore be assembled at the Rutherford Appleton Laboratory at Harwell in Oxfordshire.
Dr. Graham Turnock, Director General of the UK Space Agency, said: "Thanks to the world – leading capabilities of our innovative space community, a British consortium has been selected to advance ESA 's next scientific mission. This shows the important role we play in European research collaboration in Europe Play space.
"The Mission Ariel is a prime example of the scientific innovation that underlies the economy in general. It is based on British science and engineering, which is at the forefront of the government's industrial strategy. Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos