We found our first exoplanets orbiting a pulsar in 1992. Since then, we’ve discovered many thousands more. Those were the first steps in identifying other worlds that could harbour life.
Now planetary scientists want to take the next step: studying exoplanet atmospheres.
The ESA’s ARIEL mission will be a powerful tool.
ARIEL stands for Atmospheric Remote-sensing Infrared Exoplanet Large-survey. It’s part of the European Space Agency’s Cosmic Vision Program. ARIEL’s goal is to examine the atmospheres of about 1,000 previously-confirmed exoplanets. It’ll study the chemical composition and the thermal structures of the atmospheres.
ARIEL is still in the design study phase, and its tentative launch date isn’t until 2028. Mission planners are still working out some of the mission’s critical details. One of those details includes automatic scheduling, and a new paper looks at those techniques and how the mission might work.
The paper is “Ariel mission planning: Scheduling the survey of a thousand exoplanets.” The lead author is Juan Carlos Morales, a researcher at the Institut de Ci`encies de l’Espai in Barcelona, Spain. The paper is available at the pre-press site arxiv.org.
NASA designed missions like Kepler and TESS to finding exoplanets, which have succeeded. But ARIEL’s mission is devoted to studying exoplanets. It’ll spend its time looking at known exoplanets rather than scanning the sky for more.
ARIEL will address several questions in exoplanet science. It’ll explore exoplanet composition, the formation and evolution of planetary systems, and the physical processes that shape exoplanet atmospheres.
We’re accustomed to thinking about exoplanets in relation to the planets in our own Solar System. But exoplanet compositions can vary greatly. ARIEL will help us understand them better. This artist’s illustration shows the theoretical internal structure of the exoplanet GJ 3470 b. It is unlike any planet found in the Solar System. Weighing in at 12.6 Earth masses the planet is more massive than Earth but less massive than Neptune. Unlike Neptune, which is 3 billion miles from the Sun, GJ 3470 b may have formed very close to its red dwarf star as a dry, rocky object. It then gravitationally pulled in hydrogen and helium gas from a circumstellar disk to build up a thick atmosphere. The disk dissipated many billions of years ago, and the planet stopped growing. The bottom illustration shows the disk as the system may have looked long ago. Observation by NASA’s Hubble and Spitzer space telescopes have chemically analyzed the composition of GJ 3470 b’s very clear and deep atmosphere, yielding clues to the planet’s origin. Many planets of this mass exist in our galaxy. Image Credit: NASA.
Detailed knowledge of exoplanet atmospheres tells scientists how and where they formed. Planets form in protoplanetary disks, the disks of dust and gas that surround young stars. When scientists know about the chemical composition of an atmosphere and its thermal structure, they better understand where in the disk a planet formed and how quickly.