The NASA Pandora spacecraft will observe planets as they pass in front of their stars as seen from our perspective, events called transits.
As starlight passes through a planet’s atmosphere, it interacts with substances like water and oxygen that absorb characteristic wavelengths, adding their chemical fingerprints to the signal.
But while only a small fraction of the star’s light grazes the planet, telescopes also collect the rest of the light emitted by the star’s facing side. Stellar surfaces can sport brighter and darker regions that grow, shrink, and change position over time, suppressing or magnifying signals from planetary atmospheres. Adding a further complication, some of these areas may contain the same chemicals that astronomers hope to find in the planet’s atmosphere, such as water vapor.
All these factors make it difficult to be certain that important detected molecules come from the planet alone.
Pandora will help address this problem by providing in-depth study of at least 20 exoplanets and their host stars during its initial year. The satellite will look at each planet and its star 10 times, with each observation lasting a total of 24 hours. Many of these worlds are among the over 6,000 discovered by missions like NASA’s TESS (Transiting Exoplanet Survey Satellite).
Pandora will collect visible and near-infrared light using a novel, all-aluminum 17-inch-wide (45-centimeter) telescope jointly developed by Lawrence Livermore National Laboratory in California and Corning Specialty Materials in Keene, New Hampshire. Pandora’s near-infrared detector is a spare developed for NASA’s James Webb Space Telescope.
Each long observation period will capture a star’s light both before and during a transit and help determine how stellar surface features impact measurements.
Pandora is the first satellite to launch in the agency’s Astrophysics Pioneers program, which seeks to do compelling astrophysics at a lower cost while training the next generation of leaders in space science.