NASA’s Pandora Mission Begins Study of Exoplanets, Host Stars

Pandora, NASA’s newest exoplanet mission and the first satellite launched through the agency's Astrophysics Pioneers program, is now making unique observations of worlds beyond our solar system and the stars they orbit. The mission will determine the atmospheric make-up of at least 20 exoplanets, including the presence of hazes, clouds, and water. “Pandora’s data will help close a major gap in our knowledge about planets and their host stars because, right now, we can’t be entirely sure how the star’s light affects measurements of what makes up exoplanet atmospheres,” said Elisa Quintana, Pandora’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We designed the Pandora spacecraft and its in-depth observing program to better understand this vexing issue.” The results of the mission will lay a firm foundation for interpreting measurements by NASA’s James Webb Space Telescope, as well as future observatories focused on finding habitable worlds. In fact, Pandora’s near-infrared detector is a spare originally developed for Webb.

Three factors make Pandora unique. It carries a novel all-aluminum telescope about 18 inches (45 centimeters) in diameter, it will study planets and their host stars simultaneously in both visible and infrared light, and it will observe targets for a much longer time than flagship observatories like Webb are able to. Telescopes can sample a planet’s atmosphere in systems where the planet passes in front of its star as seen from our perspective. During this event, called a transit, some starlight skims the planet’s atmosphere before making its way to us. As this light interacts with atmospheric molecules, their chemical fingerprints become embedded in it. For each molecule, astronomers see brightness dips at characteristic wavelengths. But our instruments also see light from the whole star, not just what grazes the planet. Stellar surfaces aren’t uniform; they sport hotter, brighter areas called faculae and cooler, darker regions similar to sunspots. Both can grow, shrink, and change position as the star rotates.

“Water is one of the most important molecules we can measure to understand the composition and physical conditions of an exoplanet atmosphere,” said Benjamin Rackham, a team member at the Massachusetts Institute of Technology in Cambridge. “But features on the star can masquerade as those signals, so we need to account for them to be sure our measurements are correct.” The spacecraft is healthy and all instruments are performing as well as hoped, according to Jordan Karburn, Pandora’s deputy project manager at Lawrence Livermore National Laboratory in California, adding that the team’s commissioning work paid off and science can confidently begin. Launched into low Earth orbit on Jan. 11, Pandora is an ambitious small satellite (SmallSat) funded by NASA’s Astrophysics Pioneers program, which supports fast-paced, low-cost missions with a higher tolerance for failure.