The Ultraviolet Explorer (UVEX) mission, announced today by NASA, will give astronomers a powerful new tool to study the most energetic events in the cosmos. The space telescope will scan the entire sky in ultraviolet wavelengths, detecting objects too faint for previous observatories and rapidly turning to capture transient phenomena such as the mergers of neutron stars and the explosions of massive stars.
"UVEX is a bold leap forward in our exploration of the ultraviolet universe," said Caltech President Ray Jayawardhana. The mission is led by Caltech's Fiona Harrison, the Harold A. Rosen Professor of Physics, who also serves as principal investigator for NASA's NuSTAR X-ray observatory.
UVEX will be the first telescope to make deep maps of the entire sky in ultraviolet light with unprecedented sensitivity, up to 100 times greater than its predecessor, the Galaxy Evolution Explorer (GALEX), which Caltech also led between 2003 and 2013. The new mission adds a dedicated time-domain capability, allowing it to quickly swing across the sky to observe dramatic events as they unfold.
"The first major ultraviolet space mission in two decades, this Caltech-led effort brings together our distinctive strengths in scientific and instrumentation leadership, JPL's advanced detector technology, and IPAC's expertise in transforming mission data into a resource for astronomers around the world," Jayawardhana said.
Key to UVEX's sensitivity are innovative ultraviolet detectors built jointly by Caltech, SRI International, and NASA's Jet Propulsion Laboratory (JPL). These detectors are derived from CMOS imaging technology, invented at JPL in the 1990s and now used in billions of smartphone cameras. Shouleh Nikzad, chief technologist at JPL and a 2026 Caltech Distinguished Alumna, has led the decades-long effort to modify the sensors for ultraviolet light. "We are so proud that this partnership with Caltech has come to fruition to enable the exciting science that will be achieved by UVEX," she said.
UVEX will join a growing fleet of sky-mapping surveys, including the Caltech-led SPHEREx mission (infrared), the Vera C. Rubin Observatory (visible light), NASA's Nancy Grace Roman Space Telescope, and the Zwicky Transient Facility (ZTF). The mission is particularly well-suited to spotting millions of small nearby galaxies that are teeming with new stars but difficult to see in visible light.
"In optical light, it's very hard to distinguish these nearby galaxies from faraway ones that look similar," Harrison said. "Ultraviolet light will make them easier to find."
Harrison noted the untapped potential in ultraviolet astronomy. "I could not resist the untapped opportunity in the ultraviolet," she said, adding that the mission will advance fundamental frontiers in astrophysics, from understanding the smallest galaxies to diagnosing the aftermaths of neutron-star mergers and other cosmic explosions.
Caltech and UC Berkeley's Space Sciences Laboratory will lead the development of the UVEX instrument, while Northrop Grumman will build the spacecraft. JPL will provide key detector technology, and Caltech's IPAC data center will process and archive the mission's data.