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ARIEL Mission selected by ESA


On March 20, the ARIEL Space Mission (Atmospheric Remote-Sensing Infrared Exoplanet Large-survey) was selected by the European Space Agency (ESA) to study the atmosphere of planets orbiting distant starts and acquire further information on their formation and development. One of the mission proponents is telescope scientist Enzo Pascale from the Sapienza Department of Physics.

ARIEL, which will be launched in 2028, will observe 1000 exoplanets over the course of four years, completing the first systematic survey of their chemical elements and the temperatures and pressure of their atmospheres. The mission addresses one of the key themes of the universe: what are the conditions for planet formation and the emergence of life?

In the last twenty years or so, over 3700 planets orbiting distant starts, exoplanets, have been discovered. With few exceptions, these planets cannot be viewed directly, but their existence can be deduced by the effect they have on sun light, the mother star around which they orbit.

“We still know very little, too little, about these worlds,” explains Professor Pascale. “We know the diameters and average densities of these planets, but we need to study what they are made of, whether they have an atmosphere and what its composition is. We need to measure its physical parameters, such as temperature and pressure. This is exactly what ARIEL will do. It will provide us with a statistically representative vision of these alien worlds. It will allow us to understand how chemistry is related to the planet’s environment and how the mother star influences the processes of planetary birth and evolution.”

This knowledge will be fundamental for the advancement of our understanding of the formation and development of planets, as well as the unique nature of our solar system in the universe.

ARIEL’s eye is a one-meter wide telescope that can capture both visible and infrared light from alien solar systems. Three on board spectrometers will divide the captured light into its chromatic constituents, which will reveal the chemical composition of the atmospheres that emitted or filtered the light. The probe’s tools also include three photometers that can identify the presence of extra-terrestrial clouds and point ARIEL towards any star with great precision and stability.

The dimension of the planets that will be studied is similar to that of Jupiter and Neptune, as well as so-called “super Earths,” planets with a diameter just slightly larger than ours. Moreover, the mission will not observe any planets in the “inhabitable zone,” but warmer planets with temperatures ranging from 300 to 2000 degrees Celsius, which are of great scientific interest. High temperatures mean that the planets’ atmospheres are well mixed. And this will allow ARIEL to identify all the chemical elements present, including the heavier ones that normally remain hidden in colder and more stratified atmospheres, such as Jupiter and Neptune.

“ARIEL’s selection is exceptional news,” comments Prof. Pascale. “There are many planets in our galaxy and they are all over the place. On average there is one planet for every star. ARIEL will allow us to understand our solar system in the greater galactic context.”

The ARIEL Mission Consortium includes the Italian National Astrophysics Institute (INAF), the National Research Council and the University of Florence with support from the Italian Space Agency, besides scientists and engineers from 50 research institutes in Great Britain, France, Poland, Spain, Holland, Belgium, Austria, Denmark, Ireland, Germany, Hungary, Portugal, the Czech Republic and Sweden.