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Pandora, NASA's newest exoplanet mission and the first satellite to launch 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.
"The spacecraft is healthy and all of the instruments are performing as well as we could have hoped," said Jordan Karburn, Pandora's deputy project manager at Lawrence Livermore National Laboratory in California. "Our team's hard work throughout the commissioning process has paid off, and we can now confidently start science."
Launched into low Earth orbit on Jan. 11, Pandora is an ambitious small satellite (SmallSat) funded by NASA's Astrophysics Pioneers program. Pioneers are designed to explore compelling questions about the universe with fast-paced, low-cost missions that require a higher-than-usual tolerance for failure.
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 distort the water signal we're searching for. Pandora is designed to disentangle the signals from the planet and the star, helping us to understand the planets more accurately and laying the groundwork for the eventual study of planets that could harbor life."
