PASADENA, Calif. — NASA has turned off its Galaxy Evolution Explorer
(GALEX) after a decade of operations in which the venerable space
telescope used its ultraviolet vision to study hundreds of millions of
galaxies across 10 billion years of cosmic time.
"GALEX is a remarkable accomplishment," said Jeff Hayes, NASA's GALEX
program executive in Washington. "This small Explorer mission has
mapped and studied galaxies in the ultraviolet, light we cannot see with
our own eyes, across most of the sky."
Operators at Orbital Sciences Corporation in Dulles, Va., sent the
signal to decommission GALEX at 12:09 p.m. PDT (3:09 p.m. EDT) Friday,
June 28. The spacecraft will remain in orbit for at least 65 years, then
fall to Earth and burn up upon re-entering the atmosphere. GALEX met
its prime objectives and the mission was extended three times before
being cancelled.
Highlights from the mission's decade of sky scans include:
- Discovering a gargantuan, comet-like tail behind a speeding star called Mira.
- Catching a black hole "red-handed" as it munched on a star.
- Finding giant rings of new stars around old, dead galaxies.
- Independently confirming the nature of dark energy.
- Discovering a missing link in galaxy evolution -- the teenage galaxies transitioning from young to old.
The mission also captured a dazzling collection of snapshots, showing
everything from ghostly nebulas to a spiral galaxy with huge, spidery
arms.
In a first-of-a-kind move for NASA, the agency in May 2012 loaned
GALEX to the California Institute of Technology in Pasadena, which used
private funds to continue operating the satellite while NASA retained
ownership. Since then, investigators from around the world have used
GALEX to study everything from stars in our own Milky Way galaxy to
hundreds of thousands of galaxies 5 billion light-years away.
In the space telescope's last year, it scanned across large patches
of sky, including the bustling, bright center of our Milky Way. The
telescope spent time staring at certain areas of the sky, finding
exploded stars, called supernovae, and monitoring how objects, such as
the centers of active galaxies, change over time. GALEX also scanned the
sky for massive, feeding black holes and shock waves from early
supernova explosions.
"In the last few years, GALEX studied objects we never thought we'd
be able to observe, from the Magellanic Clouds to bright nebulae and
supernova remnants in the galactic plane," said David Schiminovich of
Columbia University, N.Y., N.Y, a longtime GALEX team member who led
science operations over the past year. "Some of its most beautiful and
scientifically compelling images are part of this last observation
cycle."
Data from the last year of the mission will be made public in the coming year.
"GALEX, the mission, may be over, but its science discoveries will
keep on going," said Kerry Erickson, the mission's project manager at
NASA's Jet Propulsion Laboratory in Pasadena, Calif.
JPL managed the GALEX mission and built the science instrument. The
mission's principal investigator, Chris Martin, is at Caltech. NASA's
Goddard Space Flight Center in Greenbelt, Md., developed the mission
under the Explorers Program it manages. Researchers sponsored by Yonsei
University in South Korea and the Centre National d'Etudes Spatiales
(CNES) in France collaborated on the mission. Caltech manages JPL for
NASA.
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