Amy Mainzer, a UCLA astronomer and leader of NASA’s planetary defense missions, emphasizes the importance of early detection in preventing asteroid impacts on Earth. “We can’t do anything about an incoming asteroid if we don’t know it’s there,” Mainzer said. She explained that having years or decades of advance notice provides time to study an object and potentially deflect it.
Mainzer previously led NASA’s NEOWISE mission, which used a repurposed space telescope to identify and study comets and asteroids near Earth. NEOWISE, which concluded operations in 2024, identified over a hundred thousand asteroids and comets, including several thousand that pass close to Earth’s orbit. More than 200 of these were newly discovered objects.
Mainzer is now heading the design of NEO Surveyor, a new space telescope specifically intended to detect objects that could threaten Earth. However, she expressed concern about the future of such projects as Congress considers significant funding cuts for federal agencies involved in space science.
Since NASA’s Double Asteroid Redirection Test (DART) impacted its target in September 2022—altering the orbit of the asteroid moonlet Dimorphos by 33 minutes—the team has confirmed that kinetic impactor techniques can effectively change an asteroid’s trajectory.
Astronomers are currently tracking more than 95 percent of near-Earth asteroids at least one kilometer wide. “That sounds great until you realize that’s about the size of the object that killed the dinosaurs,” Mainzer said. She noted that while extinction-level impacts are rare, smaller asteroids still pose risks. For example, in 2013, a meteorite exploded over Chelyabinsk, Russia, injuring over a thousand people after shock waves shattered windows across the city.
The Chelyabinsk meteorite was less than 20 meters across before breaking up in the atmosphere. A fragment from this event is now housed at UCLA’s Meteorite Museum. Mainzer highlighted that many smaller but still dangerous asteroids remain undetected: “And as it turns out, we don’t know where most of them are right now.”
NEO Surveyor aims to address this gap with improved technology such as a higher-resolution camera and optimized orbit for detecting small and dark objects. The mission is scheduled for launch no earlier than September 2027.
“Yes, it’s rocket science, but it’s doable rocket science,” Mainzer said. She stressed that building better telescopes is achievable with continued investment.
Historically, U.S. government funding has been crucial for advancements in planetary defense; over 98 percent of known near-Earth objects have been found by NASA-funded projects.
Mainzer warned that proposed budget cuts could hinder both ongoing research and future training for scientists and engineers: “If we lose that continuous supply of well-trained scientists and engineers, that loss will reverberate for decades afterwards.”
