NASA Clears $590 Million UVEX Telescope to Map the Ultraviolet Sky

NASA’s Ultraviolet Explorer, or UVEX, has passed a review that moves the telescope into construction, with launch planned by January 2031, the agency announced on Oct. 27, Sky & Telescope reported. The mission will survey the entire sky in near- and far-ultraviolet light to study newborn stars, exploding stars and collisions between neutron stars.

No dedicated ultraviolet observatory has flown since the Galaxy Evolution Explorer was shut down in 2013. Caltech, which leads the mission, calls it the first major ultraviolet space mission in two decades.

Why ultraviolet astronomy needs space

The ozone layer soaks up most ultraviolet light before it reaches the ground, so telescopes on Earth cannot see it. Many of the most violent events in the universe give off strong ultraviolet light, and studying them means going above the atmosphere.

Few NASA instruments cover this part of the spectrum now. Hubble reaches only the near-ultraviolet and has many other demands on its time. NASA’s decision on UVEX also came days before the agency lost the Neil Gehrels Swift Observatory, which carried an ultraviolet telescope.

What UVEX will be able to do

The telescope is built around a 30-inch mirror. According to Sky & Telescope, it will have sharper resolution than earlier ultraviolet missions and see fainter objects. Its main abilities:

• Spectra that cover a wide band from the near- to the far-ultraviolet
• Images 100 times deeper than any made before at these wavelengths
• A wide field of view with high resolution, suited to surveying the whole sky

Over its planned two-year mission, UVEX will repeat its surveys on schedules that range from 12 hours to 6 months. That lets it catch objects that change quickly, such as gamma-ray bursts and supernovae, and follow up on them fast, something earlier ultraviolet missions could not do. It will also look for ultraviolet light from the same events that produce gravitational waves.

What it means for questions about galaxies and elements

A deep ultraviolet map should turn up faint, low-mass galaxies. Astronomers hope the survey will show how small galaxies grow into large ones like the Milky Way and beyond. It should also help explain how supernovae and neutron star mergers scatter heavy elements into space, where they shape later generations of stars.

Who is building it and what it costs

UVEX is a medium-class mission in NASA’s Explorers program, with a lifecycle cost of $590 million. Earlier missions in that class include Swift, the asteroid survey NEOWISE and the planet hunter TESS. Caltech, NASA’s Jet Propulsion Laboratory and the Space Sciences Laboratory at the University of California, Berkeley, are developing the instruments, and Northrop Grumman will build the spacecraft.

The telescope will fly in an orbit like TESS’s, an elongated path in step with the Moon that carries it around Earth about twice a month. That orbit is stable and stays clear of the Van Allen radiation belts.

What happens next

The project now enters assembly, integration and testing, the steps that lead up to launch.

Source: Sky & Telescope