The European Space Agency (ESA) has finally shortlisted one of the three candidates for its next science mission due in mid-2028. The ARIEL mission which is an acronym for “Atmospheric Remote-sensing infrared Exoplanet Large-survey” won the race to be the part of ESA’ Cosmic Vision. ARIEL will examine the condition for planet formation and the chemistry behind exoplanets and if it is potentially habitable for life or not. ARIEL is a medium-class science mission that will scan the skies and the space to detect more than 1,000 exoplanets orbiting their stars in the distant background as per its estimates.
According to the reports published in support of ESA’ ARIEL, it will collect data of the exoplanets and the chemistry of their atmospheres. The data collected with the mission will help determine how planetary systems across these types of stars form. It will also answer the questions like how the chemistry of star’s atmospheres helped build a myriad of planets that we see today. ARIEL will be equipped with an Afocal 3-mirror telescope, a broadband spectrometer with a modular architecture, photometric bands, and other components that will be combined to make it work in the space.
ARIEL is currently being developed by a consortium of 60+ institutes from 15 ESA state countries. The official proposal of ARIEL stated that its crucial objectives are to study planetary atmospheres, structures, and their composition. Moving further, it will study the energy budget that includes temperature and albedo along with planetary interiors by breaking down the radius-mass degeneracy. The mission is equipped with instruments that can detect vertical and horizontal temperature along with seasonal and diurnal variations of any given exoplanet. With its state-of-the-art scientific instruments, the mission will assess the photochemistry, thermochemistry, and transport quenching of the planets.
The observational strategy of the mission is to detect transit and eclipse spectroscopy of planets. As per estimates, the mission will survey at least 500 transiting exoplanets from their stars with the size of super-Earths, gas giants, super-Neptunes, hot-Jupiters, including the stars with very warm temperatures. The objective to pick up warm temperature is because high temperature allows the molecules in the atmosphere to mix-well. It also prevents them from forming cloud layers and sinking into the depth which combinedly makes them easier to detect.
According to the inputs published in the proposal, ARIEL will use its meter-class telescope to scan molecules in the atmospheres of exoplanets in visible and infrared wavelengths that will help assess and evaluate the chemistry as well as metallicity of the stars that facilitated the formation of a planet.
Since the mission has just been approved, the European Space Agency has quoted the estimated launch window in mid-2028. It will be launched on a Vega-C rocket from Kourou into LEO orbit and then, it will be transferred to the Halo Orbit using LISA Pathfinder based propulsion module. The spacecraft aboard the rocket will have a dimension of 2.2m x 2.2m x 3.3m when stowed and 3.8m x 2.2m x 3.3m upon deployment of solar arrays. It will be equipped with 750 kg S/C dry mass plus 1150 kg of propellant which will be used for internal propulsion for the during of the mission. It will be equipped with thermal control system and attitude control system along with 80Gbit data per week telemetry using a High Gain Antenna to the 35 m ESTRACK Station located across the globe.
Gunther Hasinger, ESA Director of Science said in an interview that ARIEL mission is a next logical step in the exploration of exoplanets and it will answer questions related to the formation and evolution of these planets around their host stars. This will, in turn, help us understand our(Earth’s) place in the Universe [paraphrased].
The ARIEL M4 proposal is available here.