Key facts
- UVEX will enable ultraviolet follow-up observations of gravitational-wave events, such as neutron star and black hole mergers, providing detailed spectra to study their environments and emission processes.
- UVEX will rapidly detect and observe transient events like stellar flares, exploding stars, and tidal disruption events, which are often invisible or poorly observed in visible light.
- UVEX’s baseline mission will last two years, during which it will conduct a multi-cadence all-sky survey, rapid follow-up observations of transient events, and spectroscopic follow-up of stars and galaxies.
- UVEX will focus on low-mass, low-metallicity galaxies, which contain half of the universe’s stellar mass and serve as analogs for the universe’s first galaxies, to study their star formation and stellar evolution.
NASA announced on Oct. 28, 2026, that the UltraViolet EXplorer (UVEX), a telescope led by Caltech, will launch in 2031 to conduct an all-sky survey in near- and far-ultraviolet light.
The mission responds to a 20-year gap in ultraviolet observations created when NASA’s GALEX telescope ended its work in 2013. NASA is presenting UVEX as the first new ultraviolet telescope mission in that period. The gap has left ultraviolet views of transient events and slow celestial changes out of reach, because many of those phenomena are invisible at other wavelengths.
UVEX will also be the first ultraviolet mission to create deep-sky maps in ultraviolet light. Those maps will support long-term monitoring of celestial changes, including slow evolutionary processes and brief transient events.
UVEX will be up to 100 times more sensitive than GALEX, producing a survey 50 times deeper in near-ultraviolet light and 100 times deeper in far-ultraviolet light. The jump will let UVEX detect dim ultraviolet sources invisible to GALEX, including transient events such as stellar flares and exploding stars. The two-year baseline mission will combine wide sky coverage with fast, targeted observations.
During those two years, UVEX will run a multi-cadence all-sky survey, provide rapid follow-up observations of transient events, and carry out spectroscopic follow-up of stars and galaxies. The design pairs broad coverage with targeted observations to support long-term monitoring and rapid response. Revisiting the same sky regions will let astronomers track how objects change over time.
UVEX will quickly find and observe transient events such as stellar flares, exploding stars, and tidal disruption events, many of which are invisible or poorly observed in visible light. Catching these fast-changing events is central to studying dynamic cosmic processes.
UVEX’s mission rests on three pillars: studying low-mass, low-metallicity galaxies; exploring dynamic events such as gravitational-wave mergers and stellar explosions; and producing an ultraviolet dataset for public research. The first pillar covers star formation and galaxy evolution in low-metallicity environments, while the second emphasizes rapid follow-up of tidal disruption events and other ultraviolet transients.
UVEX’s spectroscope will separate light into different wavelengths to identify the chemical elements present in stellar explosions and mergers. The telescope will also follow up gravitational-wave events from neutron star and black hole mergers, adding detailed spectra to studies of those collisions. When gravitational-wave observatories detect a merger, UVEX will join other telescopes in multi-wavelength observations, offering insight into the early stages of these cosmic events.
A major science target is low-mass, low-metallicity galaxies, which hold half of the universe’s stellar mass and serve as analogs for the universe’s first galaxies. UVEX will study how stars form and evolve in those systems. Their low metallicity and proximity allow UVEX to observe processes otherwise obscured in more distant, high-redshift galaxies, opening a view of early universe conditions.
Because those galaxies are bright in ultraviolet light, UVEX’s observations will complement infrared studies of distant galaxies by the James Webb Space Telescope and the Nancy Grace Roman Space Telescope. The pairing will help astronomers interpret redshifted infrared light from early galaxies, bridging research on the local and distant universe.
UVEX will repeatedly observe the Large and Small Magellanic Clouds throughout its baseline mission. Those repeat surveys will produce detailed ultraviolet records of stellar populations and evolutionary processes in both nearby galaxies. The work will complement the broader all-sky survey coverage.
UVEX will work alongside infrared surveys from the Nancy Grace Roman Space Telescope, visible-light surveys from the Vera Rubin Observatory, and visible-light observations from ESA’s Euclid Space Telescope. Together the datasets will enable comprehensive studies of celestial objects and phenomena across wavelengths, enhancing understanding of cosmic evolution.
UVEX will build a large public archive of ultraviolet observations for researchers worldwide, like the long-term data legacy of ESA’s Gaia mission. The open-access approach will enable collaborative studies across astronomy, astrophysics, and related fields, keeping UVEX’s legacy useful beyond its operating life.
Ray Jayawardhana, president of Caltech, called the mission a bold leap forward in exploring the ultraviolet universe. Caltech is leading the UVEX mission. His statement underscores the mission’s significance for advancing ultraviolet astronomy and its potential to reveal unexpected discoveries.
Kareem El-Badry, a member of the UVEX team, expects the telescope to turn up unexpected discoveries, pointing to past surprises from the James Webb Space Telescope’s study of early supermassive galaxies. Exploring new wavelengths often uncovers phenomena not visible elsewhere, driving advances in astrophysical understanding. “Every time you look at the skies in a new wavelength, you learn something new and unexpected.” — Kareem El-Badry
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