Fifteen years after a launch that was intended to begin just a seven month mission, NASA’s NEOWISE spacecraft has finally shut down. The Near-Earth Object Wide-field Infrared Survey Explorer spacecraft surveyed the sky spotting thousands of asteroids within our solar system, and made discoveries such as a striking comet that as named after it. The spacecraft has made years of scientific observations, but with its orbit slowly dropping, it has now been decommissioned and will burn up harmlessly in the atmosphere later this year.
NEOWISE was a remarkable mission for several reasons, one of which was that it was never intended to be an asteroid observation mission at all. It was originally launched as WISE, the Wide-field Infrared Survey Explorer, and looked at distant objects like galaxies in the infrared. Its original mission was successful and so was extended, but within a couple of years the spacecraft had used up the coolant required for some of its detectors and it was put into hibernation.
Years later, in 2013, NASA wanted a mission to look for asteroids and comets that come close to Earth, called near-Earth objects. Scientists realized that WISE could be reactivated for this job, using its remaining detectors. The mission was reactivated as NEOWISE, and since then has taken images of the sky, including 1.45 million measurements of more than 44,000 solar system objects. That including detected over 3,000 near-Earth objects, 215 of which had never been observed before.
“The NEOWISE mission has been instrumental in our quest to map the skies and understand the near-Earth environment. Its huge number of discoveries have expanded our knowledge of asteroids and comets, while also boosting our nation’s planetary defense,” said Laurie Leshin, director of NASA’s Jet Propulsion Laboratory, in a statement. “As we bid farewell to NEOWISE, we also celebrate the team behind it for their impressive achievements.”
The final image taken by NEOWISE shows the night sky as seen in the direction of the Fornax constellation. It was images like these that allowed scientists to spot previously unseen objects, which could then be flagged for follow-up observations from telescopes on the ground to see how these objects were moving and to work out their orbits — and whether they could pose any threat to Earth.
That role will soon be taken up by a purpose-build spacecraft called NEO Surveyor, which will use infrared to search for dark-colored asteroids that might otherwise be missed and to check whether any of these could come close to the planet. NEO Surveyor is set to launch in 2027.
“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,” said Nicola Fox, associate administrator of NASA’s Science Mission Directorate. “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.”
