NASA engineers have switched off the transmitter on the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) for the last time, ending its ten-year mission to search for asteroids and comets.
The turn-off command was sent from the Earth Orbiting Missions Operation Center at NASA’s Jet Propulsion Laboratory in Southern California on July 8, 2024. NASA’s Tracking and Data Relay Satellite System then relayed the signal to NEOWISE, decommissioning the spacecraft. The spacecraft’s science survey ended on July 31 when NASA downlinked all remaining science data from the spacecraft.
“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 NASA’s Nicola Fox.
NASA ended the mission because NEOWISE will soon drop too low in its orbit around Earth to provide usable science data. An uptick in solar activity is heating the upper atmosphere, causing it to expand and create drag on the spacecraft, which does not have a propulsion system to keep it in orbit. Now decommissioned, NASA expects NEOWISE to safely burn up in Earth’s atmosphere in late 2024.
During its operational lifetime, the infrared survey telescope exceeded scientific objectives for not one but two missions, starting with the WISE (Wide-field Infrared Survey Explorer) mission. WISE launched in December 2009 with a seven-month mission to scan the entire infrared sky. By July 2010, WISE had accomplished this with far greater sensitivity than previous surveys. However, a few months later, the telescope ran out of the coolant that kept heat produced by the spacecraft from interfering with its infrared observations.
NASA extended the mission under the name NEOWISE until February 2011 to complete a survey of the main belt asteroids, at which point the agency put the spacecraft into hibernation. Analysis of this data showed that although the lack of coolant meant the space telescope could no longer observe the faintest infrared objects in the universe, it could still make precise observations of asteroids and comets that generate a strong infrared signal from being heated by the Sun as they travel past our planet.
Consequently, NASA brought the telescope out of hibernation in 2013 under the Near-Earth Object Observations Program, a precursor for the agency’s Planetary Defence Coordination Office, to continue the NEOWISE survey of asteroids and comets.
By repeatedly observing the sky from low Earth orbit, NEOWISE created all-sky maps featuring 1.45 million infrared measurements of more than 44,000 solar system objects. Of the 3,000-plus near-Earth objects it detected, 215 were first spotted by NEOWISE. The mission also discovered 25 new comets, including the famed comet C/2020 F3 NEOWISE in 2020. In addition to leaving behind a trove of scientific data, the spacecraft has helped inform the development of NASA’s first infrared space telescope, the NEO Surveyor, which was purpose-built for detecting near-Earth objects.
“The NEOWISE mission has provided a unique, long-duration data set of the infrared sky that will be used by scientists for decades to come,” said NASA’s Amy Mainzer. “But its additional legacy is that it has helped lay the groundwork for NASA’s next planetary defence infrared space telescope.”
NEO Surveyor will seek out some of the hardest-to-find near-Earth objects, such as dark asteroids and comets that don’t reflect much visible light, as well as objects that approach Earth from the direction of the Sun. Construction of NEO Surveyor is already well underway, with a launch date expected no earlier than 2027.
