NASA Plans a Space Telescope That Sees the Sky in Ultraviolet, Launching 2031

NASA has announced that UVEX, the UltraViolet EXplorer, will launch in 2031. According to Universe Today, the space telescope will survey the entire sky in near and far ultraviolet light, a band that human eyes cannot see and that reveals events hidden from ordinary stargazing.

The mission will be led by Caltech. Universe Today reported that UVEX is designed to catch stellar flares, exploding stars and other sudden events that show up fully only in ultraviolet light.

Why the night sky looks calmer than it is

To most observers, the night sky changes little: the Moon waxes and wanes, planets drift, and a meteor streaks past now and then. Universe Today argues that this calm is an illusion created by the fact that people see only visible light. In ultraviolet, it says, violent and short-lived events happen almost continuously.

Caltech President Ray Jayawardhana called UVEX a bold leap forward in exploring the ultraviolet universe. UVEX team member Kareem El-Badry said that looking at the sky in a new wavelength always teaches scientists something new and unexpected.

How UVEX compares with earlier ultraviolet missions

A white paper cited by Universe Today says UVEX will carry out a two-year baseline mission. Its survey is planned to go 50 times deeper than GALEX in near-ultraviolet light and 100 times deeper in far-ultraviolet light. GALEX was a NASA ultraviolet space telescope whose mission ended in 2013. Universe Today describes UVEX as up to 100 times more sensitive than that earlier observatory.

The authors also list repeated surveys of the Large and Small Magellanic Clouds, rapid follow-up of sudden events, and spectroscopic follow-up of samples of stars and galaxies. Besides the sky survey, the telescope will also make focused observations of individual targets.

Three goals behind the mission

Universe Today, drawing on a paper describing the mission, says UVEX rests on three pillars.

• Low-mass galaxies. UVEX will study small galaxies with few heavy elements to learn how star formation and the life cycles of stars affect their growth. Universe Today says this population holds half of the Universe's mass and resembles the first galaxies.
• A changing sky. Repeated surveys and quick spectroscopic follow-up should probe the aftermath of mergers of compact objects discovered through gravitational waves, find hot and fast ultraviolet flashes, and track the early stages of stellar explosions.
• A shared data archive. Like other survey missions, UVEX will produce a large body of ultraviolet data for researchers studying many kinds of objects. Universe Today compares this to the European Space Agency's recently completed Gaia mission, whose data is used across many fields.

What this means for astronomy fans and researchers

Most people picture space telescopes as machines that deliver sharp pictures of faraway objects. Universe Today notes that survey telescopes matter just as much because they build large datasets that many scientists can use. UVEX is meant to add the ultraviolet view to a growing set of surveys.

The other surveys named include the Nancy Grace Roman Space Telescope, which will run three surveys in infrared, and the Vera Rubin Observatory, which will image the night sky repeatedly over a decade. They also include Euclid, which is conducting three deep-field surveys in visible light and has captured over 10 billion sources, and NASA's SPHEREx, which is surveying the whole sky in near-infrared.

The ultraviolet data will also connect to what the James Webb Space Telescope and Roman see. Universe Today explains that distant low-mass galaxies have their light stretched into the infrared on its way to Earth. UVEX will study nearby counterparts in ultraviolet, which should help scientists interpret those distant observations.

What happens next

The launch is scheduled for 2031. Before then, the details of the observing program and the instrument will continue to take shape, as the mission planning documents cited by Universe Today describe them.

Around Prague, based on reporting by Universe Today