After 10 years and nearly 27 million images, NASA said goodbye to the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission last week when its transmitter was turned off. The spacecraft began life as a space telescope tasked with uncovering distant galaxies but became so much more by searching for potentially hazardous comets and asteroids throughout our solar system.
Despite its ability to change objectives, it could not change outside influences. According to a NASA news release, the Sun’s recent increase in activity has caused Earth’s atmosphere to expand, generating drag on the craft, which lacked a way to boost its orbit back up. Astronomers expect the telescope will burn up in the atmosphere later this year.
The craft finished its final survey on July 31, followed by NASA retrieving all of its remaining scientific data before taking it offline August 8.
“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, NASA associate administrator, in the release. “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.”
When it was WISE
In December 2009, the Wide-field Infrared Survey Explorer (WISE) was launched as a 7-month mission to take infrared images of the entire sky. Those images cast doubt on the existence of Planet X, uncovered the brightest galaxy in the universe, and helped astronomers find many black holes and cool stars, which stand out at the infrared wavelengths of WISE’s search.
However, by September 2010, the telescope was running out of coolant, causing the heat from the craft to interfere with the infrared sensor’s precision. So, NASA changed course.
The telescope was still able to capture images of nearby objects because of their strong infrared signals, thanks to heating from the Sun, which stand out against the background sky. The spacecraft’s mission was extended and WISE was branded NEOWISE, with the space telescope carrying out a survey of main-belt asteroids orbiting between Mars and Jupiter. That ended in February 2011, when the craft was sent into hibernation.
NEOWISE was then resurrected in 2013, now tasked with studying the size and composition of comets and asteroids passing close to Earth as part the Near-Earth Object Observations Program, the precursor to NASA’s Planetary Defense Coordination Office.
Related: From discovery to data: How astronomers track near-Earth asteroids
Earth’s lookout
During its lifetime, NEOWISE has taken 1.45 million measurements of 44,000 objects throughout the solar system, detected 215 near-Earth objects, and found 25 new comets, including C/2020 F3 (NEOWISE). It ultimately took 26,886,704 exposures.
As NEOWISE burns up in the atmosphere later this year, scientists will be working hard to get its successor, Near-Earth Object Surveyor (NEO Surveyor) ready for launch in 2027. The new space telescope will employ two heat-sensing infrared sensors, able to detect both dark and bright asteroids as they come within 30 million miles (48.3 million kilometers) of Earth. During its expected five-year-long mission, NEO Surveyor will detect objects down to sizes of about 460 feet (140 meters), which is about the height of the Great Pyramids.
