NASA's NEOWISE mission, an essential part of the agency's planetary defense efforts, is nearing its end after a remarkable 14-year run.
The spacecraft, which has significantly advanced our understanding of near-Earth objects (NEOs), will be decommissioned on July 31, 2024. As the mission concludes, NASA is already looking ahead to its successor, the NEO Surveyor, which is set to launch in late 2027.
NASA's NEOWISE: A Legacy of Discovery
Initially launched as the Wide-field Infrared Survey Explorer (WISE) in December 2009, the spacecraft's primary mission was to scan the entire sky in infrared. The mission was a tremendous success, exceeding its initial objectives by identifying tens of millions of cosmic objects, including distant galaxies, comets, and supermassive black holes. By July 2010, WISE had mapped the sky twice with unprecedented sensitivity, leading to an extension of its mission until 2011. During this extended phase, WISE conducted groundbreaking observations of distant cosmic phenomena and played a crucial role in identifying objects that were previously invisible to other telescopes.
During this period, WISE discovered the first known Earth Trojan asteroid and provided a census of dark, faint NEOs that are challenging to detect with ground-based telescopes. "The spacecraft has surpassed all expectations and provided vast amounts of data that the science community will use for decades to come," said Joseph Hunt, NEOWISE project manager at NASA’s Jet Propulsion Laboratory (JPL). The extensive data collected by WISE has become a valuable resource for astronomers and researchers, offering insights into the composition and behavior of various celestial bodies.
Transition to NEOWISE
In 2013, the mission was reactivated under the name NEOWISE with a new focus on hunting and characterizing NEOs. Without its cryogenic coolant, which had kept its instruments cold, the spacecraft adapted by staring into deep space to radiate excess heat, allowing it to continue its infrared observations. This innovative approach enabled NEOWISE to make 1.45 million infrared measurements of over 44,000 objects in the solar system, including more than 3,000 NEOs, 215 of which were newly discovered by the mission.
Amy Mainzer, principal investigator of NEOWISE and NEO Surveyor at the University of California, Los Angeles, highlighted the mission's impact: "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."
The Impact of Solar Activity
The end of the NEOWISE mission is driven by the solar cycle. Approximately every 11 years, the sun experiences a solar maximum, a period of heightened activity marked by increased solar flares and coronal mass ejections. These events heat Earth's atmosphere, causing it to expand and increase drag on satellites. Without a propulsion system to maintain its orbit, NEOWISE is slowly descending towards Earth and will eventually burn up in the atmosphere between late 2024 and early 2025.
"NEOWISE’s end of mission is tied to the Sun," explained Joseph Masiero, NEOWISE deputy principal investigator. "With no propulsion system for NEOWISE to keep itself in orbit, the spacecraft will soon drop too low to be usable."
Looking Ahead: NEO Surveyor
Building on NEOWISE's success, NASA is developing the NEO Surveyor, the first space telescope specifically designed to detect hazardous NEOs. Scheduled for launch in late 2027, NEO Surveyor will enhance NASA's planetary defense capabilities by seeking out the most difficult-to-find asteroids and comets that could pose a threat to Earth. This next-generation infrared telescope will continue the legacy of NEOWISE, utilizing the knowledge and techniques developed over the past 14 years.
"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," said Mainzer. This mission represents a critical step forward in NASA’s planetary defense strategy, ensuring that the agency can detect and mitigate potential threats from space.