SPHEREx Outer Photon Shield

Sara Susca, deputy payload manager and payload systems engineer for the NASA's SPHEREx mission, looks up at one of the spacecraft's photon shields at the agency's Jet Propulsion Laboratory in Southern California in October 2023. Short for Specto-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer, SPHEREx will create a map of the cosmos like no other, imaging the entire sky and gathering information about millions of galaxies. With this map, scientists will study what happened in the first fraction of a second after the big bang, the history of galaxy evolution, and the origins of water in planetary systems in our galaxy. Three concentric photon shields will surround the SPHEREx telescope to protect it from nearby light sources that could overwhelm its detectors. The shields will primarily block light from the Sun and the Earth. They also block heat; SPHEREx needs to be kept cold – below minus 350 degrees Fahrenheit (about minus 210 degrees Celsius). That's because SPHEREx detects infrared light, which is sometimes called heat radiation because it's emitted by anything warm. The heat from SPHEREx's own detectors could overwhelm their ability to image faint cosmic objects, so the spacecraft needs a way to cool the detectors down. The spacecraft stands almost 8.5 feet tall (2.6 meters) and stretches nearly 10.5 feet (3.2 meters) wide. https://photojournal.jpl.nasa.gov/catalog/PIA25784