Amy Mainzer, a UCLA astronomer and leader of NASA’s planetary defense missions, emphasizes the importance of early detection when it comes to asteroids that could threaten Earth. “We can’t do anything about an incoming asteroid if we don’t know it’s there,” Mainzer says. She explains that having years or decades of warning would allow time to study the object and potentially divert its path.
NASA’s Double Asteroid Redirection Test (DART) demonstrated in 2022 that it is possible to alter an asteroid’s trajectory using a kinetic impactor technique. The mission successfully changed the orbit of the asteroid moonlet Dimorphos by 33 minutes, showing that such interventions can be effective.
Mainzer previously led NASA’s NEOWISE mission, which used a space telescope to identify and study comets and asteroids near Earth. NEOWISE concluded operations in 2024 after cataloging over 100,000 objects, including several thousand with orbits close to Earth’s path. More than 200 of these were newly discovered near-Earth objects.
Currently, Mainzer is leading efforts on NEO Surveyor, a new space telescope designed specifically to detect potentially hazardous objects. The project faces uncertainty as Congress debates budget proposals that would reduce funding for federal science agencies. Mainzer warns this could jeopardize ongoing planetary defense work.
Thanks in part to NEOWISE, astronomers are now tracking more than 95 percent of near-Earth asteroids at least one kilometer wide—about the size believed responsible for the extinction event that killed the dinosaurs 66 million years ago. While scientists consider another such catastrophic impact unlikely in the next century, smaller asteroids still pose significant risks due to their frequency and potential for damage.
The Chelyabinsk meteorite incident in Russia in 2013 highlighted these dangers; shock waves from a meteor less than 20 meters across injured over a thousand people and damaged buildings across the city. The UCLA Meteorite Museum holds fragments from such events and serves as a research hub for studying these phenomena.
Mainzer points out: “So there are lots of smaller asteroids out there that are still capable of causing a lot of damage… And as it turns out, we don’t know where most of them are right now.” This realization drives her current work on NEO Surveyor—a telescope with improved capabilities set for launch no earlier than September 2027.
“Yes, it’s rocket science, but it’s doable rocket science,” Mainzer says. “We can build better space telescopes that will better enable us to spot these objects. It’s a problem we can absolutely solve.”
Historically, U.S. government investment has been critical for advances in space science; over 98 percent of known near-Earth objects have been identified by NASA-funded projects.
Mainzer stresses the need for continued federal support: “It takes decades to train a scientist like me.” She notes that both NASA and National Science Foundation face proposed budget cuts under the Trump administration’s fiscal plan for 2026—a move she believes could limit future planetary defense efforts and hinder training opportunities for new scientists and engineers.
“If we lose that continuous supply of well-trained scientists and engineers, that loss will reverberate for decades afterwards,” she says.
