NASA Retires Orbiting Telescope That Charted Asteroids for Over a Decade

After more than a decade of mapping the sky, NASA’s NEOWISE telescope—the Near-Earth Object Wide-Field Infrared Survey Explorer mission—has seen its last light. The project was officially decommissioned last week.

During its nearly 15-year run, NEOWISE observed the cosmos at infrared wavelengths and collected data on more than 740 million objects, including stars, galaxies and potentially hazardous asteroids, according to a statement from CalTech.

“The NEOWISE mission has been an extraordinary success story as it helped us better understand our place in the universe by tracking asteroids and comets that could be hazardous for us on Earth,” Nicola Fox, associate administrator for NASA’s Science Mission Directorate, says in a statement. “While we are sad to see this brave mission come to an end, we are excited for the future scientific discoveries it has opened by setting the foundation for the next-generation planetary defense telescope.”

Today we bid farewell to NEOWISE and celebrated its fabulous team. The mission mapped the skies and boosted our nation’s planetary defense strategy, and its legacy will live on in NEO Surveyor (being built at @NASAJPL now!). Thanks for all the science! https://t.co/yRhqvLJ5sj pic.twitter.com/i3J5SCEtgv

— Laurie Leshin (@LaurieofMars) August 8, 2024

In the spacecraft’s place, NASA will launch a new mission called the Near-Earth Object Surveyor (NEO Surveyor), which will continue the work of NEOWISE. According to NASA, NEO Surveyor will be the first infrared space telescope built to pick out hazardous near-Earth objects. It’s expected to begin hunting for these space rocks by June 2028, marking a step forward in NASA’s strategy for planetary defense, as the agency endeavors to identify 90 percent of near-Earth objects bigger than 460 feet in diameter.

NEOWISE’s legacy

Launched in 2009, the hardy telescope—known at the time as WISE—was initially designed to scan the sky in infrared, creating a map of the cosmos. But after achieving its goal, the spacecraft ran out of coolant, leaving it unable to chill its infrared detectors. Two of its infrared-wavelength bands still worked, however, and these happened to be perfect for spotting near-Earth objects, or NEOs. As such, in 2013, NASA gave it a new mission and a new name: NEOWISE. Instead of mapping the skies, its task was to watch asteroids and comets that whizzed close to Earth.

Out of the 1.4 million comets and asteroids in the solar system, more than 30,000 are classified as near-Earth objects, or those that circle within about 28 million miles of Earth’s orbit. NEOWISE could sense near-Earth objects by picking up on infrared signals generated as they become heated by the sun.

NEOWISE: Legacy of NASA's Asteroid-Hunting Telescope

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During its time in operation, the WISE/NEOWISE mission found supermassive black holes, collected data on dust and gas around stars and scoped out brown dwarfs. In 2011, it spotted the first known Earth Trojan asteroid, which travels around the sun in the same orbit as our planet. Only one other Earth Trojan asteroid has been found since.

The observatory collected almost 27 million infrared sky images and found 215 near-Earth objects—even faint ones that ground telescopes can’t pick up. Famously, astronomers used it to discover a comet in 2020, which was named NEOWISE after the telescope. The comet passed by Earth in summer that year, dazzling viewers across the Northern Hemisphere.

The NEOWISE mission was retired because the sun’s activity, which is ramping up and affects dynamics in Earth’s atmosphere, is causing the craft to slow down and fall out of orbit. As NEOWISE continues to drop, it will eventually burn up in Earth’s atmosphere, per NASA. On July 31, NEOWISE took its last image of the sky, and on August 8, NASA sent the final command to turn off its transmitter.

What’s next for planetary defense?

Once the upcoming NEO Surveyor telescope launches, it will start a five-year survey to find at least two-thirds of near-Earth objects bigger than 460 feet across. Objects this size can cause devastating regional damage if they crash into Earth.

NEO Surveyor will use two heat-sensitive infrared eyes to detect even dark asteroids—the most challenging asteroids to identify because they don’t reflect much visible light. Instead, they glow in infrared as they absorb heat from the sun. The new telescope is expected to measure nearly 20 inches in diameter, reports Will Robinson-Smith for Spaceflight Now.

The new mission “is optimized for finding the most dangerous asteroids and comets,” says Amy Mainzer, the principal investigator of NEOWISE and NEO Surveyor at UCLA, in the CalTech statement. “While we’re getting ready to say goodbye to NEOWISE, we’re looking forward to getting its powerful successor up into space in a few years.”

“It’s the end of an era,” Mainzer adds to the New York Times’ Katrina Miller, “but the beginning of a new one.”

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.