by NASA’s only space telescope dedicated to planetary defense has turned off its transmitter for the last time, ending its 15-year career of detecting near-Earth targets asteroids and comets.
The spacecraft, called NEOWISE (Near-Earth Object Wide-field Infrared Survey Explorer), went well beyond its initial seven-month mission to scan the sky for infrared signals, eventually detecting more than 200 previously unknown near-Earth objects, including 25 new ones. cometsand provided a wealth of data on 44,000 other objects that roam our solar system, according to NASA.
The NEOWISE mission, which officially ended on July 31, is finally coming to an end as the sun’s era of maximum activity, known as solar maximumthreatens to drag the satellite into Earth’s atmosphere for a final, lightning-fast reentry. The spacecraft, which lacks the propellant to propel itself into a higher orbit, has been plummeting toward Earth for years and is expected to burn up safely in the atmosphere in late 2024.
“This telescope has truly outlived its original [lifespan]” Amy MainzerProfessor at the University of California, Los Angeles, and principal investigator for NEOWISE and its planned successor, NEO Surveyor, told Live Science in an interview last year. “We got a lot more out of it than we expected.”
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Retirement and rebirth
NEOWISE was launched in 2009 as WISE, the Wide-field Infrared Survey Explorer. As a prototype version of the James Webb Space TelescopeWISE entered orbit with mission to map entire sky infrared light, searching for traces of faint, ancient emissions from the early universe.
The initial seven-month mission showed that WISE was far more sensitive than scientists had anticipated. NASA later extended the mission as NEOWISE through 2011, so the telescope could study the main asteroid belt between Mars and Jupiter. The telescope was then put into hibernation after running out of coolant, which prevented heat from the spacecraft from seeping into NEOWISE’s infrared sensors and reducing their sensitivity.
However, subsequent analysis of the telescope’s data showed that it was still able to detect nearby objects. solar system objects that reflect sunlight. Thus, NEOWISE was brought out of hibernation in 2013 to continue its study of near-Earth objects for another decade.
Among the hundreds of objects discovered by the telescope, its most famous detection is the bright comet that bears its name: comet C/2020 F3 NEOWISEwhich flew past Earth in July 2020.
A crack in the sky
The demise of NEOWISE leaves a temporary void in planetary defense from Earth’s orbit. No other NASA space telescope devotes 100 percent of its time to searching for near-Earth objects, some of which could pose a danger to our planet.
However, an even more powerful infrared telescope, dubbed NEO Surveyor, is already under development to follow on from NEOWISE’s mission, with a planned launch date of no earlier than 2027. Once deployed, NEO Surveyor will perform a full scan of the sky every two weeks, Mainzer said. A specially designed sunshade will also allow the telescope to search for celestial objects. asteroids located near the sun’s glare — a region of space considered our greatest blind spot for planetary defense.
In the meantime, scientists will rely on powerful Earth-based observatories to ensure that no near-Earth asteroids are approaching us.
“We’ll have ground-based telescopes, and these days they find the majority of objects anyway,” Mainzer said. “Catalina Sky Survey [in Arizona] and Pan-STARRS [in Hawaii] “These are the two surveys that are currently discovering the largest number of objects, and have done so for a long time.”
Using surveys like these, astronomers have mapped the orbits of more than 34,000 near-Earth asteroids, according to NASA —and none pose a threat to Earth for at least the next 100 years.
