Amy Mainzer, a UCLA astronomer and leader of NASA’s planetary defense missions, emphasized the importance of early detection in preventing asteroids from striking Earth. “We can’t do anything about an incoming asteroid if we don’t know it’s there,” Mainzer said. She added that with sufficient warning—ideally years or decades—scientists would have time to study such objects and potentially alter their course.
Mainzer referenced NASA’s Double Asteroid Redirection Test (DART), which demonstrated in 2022 that impacting an asteroid could effectively change its trajectory. The mission altered the orbit of the asteroid moonlet Dimorphos by 33 minutes, showing that kinetic impactor techniques can be used to redirect hazardous space objects.
For more than a decade, Mainzer led the NEOWISE mission, using a repurposed space telescope to identify and monitor comets and asteroids near Earth. NEOWISE concluded operations in 2024 after detecting over one hundred thousand asteroids and comets, including thousands whose orbits bring them close to Earth. More than 200 of these were previously unknown to scientists.
Currently, Mainzer is leading the development of NEO Surveyor, a new space telescope designed specifically to detect potential threats from space. However, proposed federal budget cuts could jeopardize this work. According to Mainzer, ongoing investment from the U.S. government is crucial for both planetary defense and training future experts in the field.
Astronomers estimate they are tracking over 95 percent of near-Earth asteroids at least one kilometer across—a size comparable to the object believed responsible for the extinction event that killed the dinosaurs. While such catastrophic impacts are rare, smaller asteroids continue to pose risks; for example, a meteorite less than 20 meters wide exploded over Chelyabinsk, Russia in 2013, injuring more than a thousand people.
Mainzer highlighted that many smaller but potentially dangerous asteroids remain undetected: “So there are lots of smaller asteroids out there that are still capable of causing a lot of damage,” she said. “And as it turns out, we don’t know where most of them are right now.”
The NEO Surveyor project builds on lessons learned from NEOWISE and will feature advanced technology such as improved cameras and sun shields to enhance detection capabilities. The mission is scheduled for launch no earlier than September 2027.
“Yes, it’s rocket science, but it’s doable rocket science,” Mainzer stated. She noted that continued support is needed not only for technological advancements but also for maintaining a pipeline of skilled scientists and engineers: “If we lose that continuous supply of well-trained scientists and engineers, that loss will reverberate for decades afterwards.”
America’s longstanding commitment to funding scientific research has enabled NASA-funded projects to discover over 98 percent of known near-Earth objects. Mainzer stressed that preserving this capacity depends on sustained federal investment in space science programs.
