NASA’s Wide-field Infrared Survey Explorer (WISE), launched in 2009, spent the next fourteen and half years studying the Universe in infrared wavelengths. During that time, it discovered thousands of minor planets, star clusters, and the first Brown Dwarf and Earth-Trojan asteroid. By 2013, the mission was reactivated by NASA as the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), which was tasked with searching for Potentially Hazardous Asteroids (PHAs). For ten years, the NEOWISE mission faithfully cataloged comets and asteroids that could pose a threat to Earth someday.
Unfortunately, NASA announced on July 1st that it would be decommissioning this planetary defense mission, which is expected to burn up in our atmosphere later this year. On Thursday, August 8th, the mission was decommissioned after the final command was sent from NASA’s Jet Propulsion Laboratory in Southern California and related to the spacecraft by the Tracking and Data Relay Satellite (TDRS) system. However, the scientific data NEOWISE collected during its ten years of operation will continue to inspire new discoveries!
The decision to end the mission was made because of an uptick in solar activity that’s been heating Earth’s upper atmosphere, causing it to expand and create drag on the spacecraft. This will cause NEOWISE to drop too low in its orbit to provide accurate scientific data, and NEOWISE does not have a propulsion system to maintain its orbit. Past and present mission members attended the decommissioning ceremony, which took place at the Earth Orbiting Missions Operation Center (EOMOC) at NASA JPL and the agency’s headquarters in Washington, D.C.
Animation of the many Near-Earth Objects (NEOs) that share Earth’s orbit. Credit: NASA.
The remaining scientific data was downlinked shortly after science operations officially ended on July 31st. Said Nicola Fox, associate administrator of NASA’s Science Mission Directorate at NASA HQ, in a recent NASA press release:
“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. 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.”
During its nearly fifteen years of operations, the space telescope exceeded its scientific objectives (not once but twice) by remaining in operation far longer than expected. When it first launched as the WISE mission in 2009, the mission was intended to scan the infrared sky for seven months. By July 2010, the mission had accomplished this objective with far greater sensitivity than previous IR surveys and depleted its supply of solid hydrogen coolant a few months later. The mission was then extended until February 2011 under the name NEOWISE to complete its survey of the Main Asteroid Belt, at which point it was put into hibernation.
However, analysis of the WISE/NEOWISE data revealed that it could still operate without coolant and make precise observations of less faint objects like comets and asteroids that are heated by the Sun as they fly closer to our planet – in short, Near-Earth Objects (NEOs). By 2013, NASA recommissioned the space telescope under the Near-Earth Object Observations Program, which morphed into NASA’s Planetary Defense Coordination Office (PDCO) in 2016. Data processing for WISE and NEOWISE takes place at the Infrared Processing and Analysis Center at the California Institute of Technology (Caltech).
This illustration shows NASA’s NEO Surveyor against an infrared observation of a starfield made by the agency’s WISE mission. Credit: NASA/JPL-Caltech/University of Arizona
Said Amy Mainzer, the principal investigator of NEOWISE and NEO Surveyor at UCLA:
“After developing new techniques to find and characterize near-Earth objects hidden in vast quantities of its infrared survey data, NEOWISE has become key in helping us develop and operate NASA’s next-generation infrared space telescope. It is a precursor mission. NEO Surveyor will seek out the most difficult-to-find asteroids and comets that could cause significant damage to Earth if we don’t find them first.”
The NEOWISE mission conducted about 1.45 million infrared measurements of more than 44,000 solar system objects, which were used to create all-sky infrared maps. This included 215 of the more than 3,000 NEOs detected to date and 25 new comets. This included the long-period comet C/2020 F3 NEOWISE that appeared in the night sky during the summer of 2020 and was the brightest comet seen in the northern hemisphere since Comet Hale–Bopp streaked across the sky in 1997.
“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, the director of NASA JPL. “As we bid farewell to NEOWISE, we also celebrate the team behind it for their impressive achievements.”
In addition to leaving behind volumes of scientific data, WISE and NEOWISE helped pave the way for NASA’s next-generation infrared space telescope. This mission, the Near-Earth Object Surveyor (NEO Surveyor), will be the first purpose-built mission dedicated to monitoring potentially hazardous NEOs. Once operational, it will seek out some of the faintest NEOs, such as asteroids and comets with low albedos (meaning they don’t reflect much visible light) or those that approach Earth from the direction of the Sun. This telescope is currently under construction and will launch no earlier than 2027.
Further Reading: NASA
