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 potentially impact Earth. “We can’t do anything about an incoming asteroid if we don’t know it’s there,” Mainzer says. She notes that having years or decades of warning would allow scientists time to study threatening objects and possibly intervene to prevent a collision.
NASA’s Double Asteroid Redirection Test (DART) demonstrated in 2022 that using a kinetic impactor can change an asteroid’s trajectory. The mission successfully altered the orbit of Dimorphos, an asteroid moonlet, by 33 minutes. This technique is now considered a viable option for deflecting hazardous asteroids.
Mainzer previously led the NEOWISE mission, which used a repurposed space telescope to identify and track asteroids and comets near Earth’s orbit. Before going offline in 2024, NEOWISE discovered over 100,000 such objects, including several thousand near-Earth objects—over 200 of which were previously unknown.
Currently, Mainzer leads efforts on NEO Surveyor, a new space telescope designed specifically to find objects that could threaten Earth. However, ongoing work may be affected by proposed federal budget cuts under consideration by Congress. These cuts would reduce funding for agencies like NASA and the National Science Foundation that have historically supported space science initiatives.
Astronomers estimate they are tracking more than 95 percent of near-Earth asteroids at least one kilometer wide—a size comparable to the object believed responsible for the extinction of the dinosaurs—but smaller asteroids remain largely untracked. Mainzer highlights past incidents such as the Chelyabinsk meteorite in Russia in 2013 as reminders that even small space rocks can cause significant damage.
Mainzer states: “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. That was a bit surprising to me. And I thought, wow, we should work on that.”
The upcoming NEO Surveyor mission aims to improve detection capabilities with advanced instruments and is scheduled 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.”
She also stresses the importance of continued government investment: “It takes decades to train a scientist like me,” she says, noting her own training was funded by NASA and the National Science Foundation. Proposed budget reductions could not only hinder planetary defense efforts but also reduce opportunities for developing future experts in this field.
“If we lose that continuous supply of well-trained scientists and engineers, that loss will reverberate for decades afterwards,” Mainzer warns.
