- September 04, 2026
- By Karen Shih ’09
- Photos courtesy of NASA
Hurtling through the solar system at more than 30,000 mph, an asteroid striking Earth could have ripple effects for all of humanity. The dinosaurs had no warning 66 million years ago. Luckily for us, there’s Kelly Fast M.S. ’93, Ph.D. ’05.
As NASA’s acting planetary defense officer, she oversees U.S. efforts and global coordination to survey the sky, calculate orbits, study physical properties and identify possible impact risks of near-Earth objects. When observations in early 2025 showed asteroid 2024 YR4—half the length of a football field—on a potential crash course with Earth in 2032, she had to make the nerve-wracking call to notify U.S. agencies for NASA and the United Nations on behalf of the International Asteroid Warning Network (IAWN).
A flurry of global news stories followed as the probability kept increasing, peaking at 1 in 30. By the end of February, though, additional observations narrowed down 2024 YR24’s future path; Earth was in the clear.
For Fast and her colleagues, 2024 YR4 turned out to be a good exercise of the entire system as well as a reminder of why they do the work: “It’s all about finding the asteroids before they find us,” she says.
The Hollywood-raised Fast developed her love of astronomy from watching “Star Trek” and “Space: 1999” rather than “Armageddon.” After earning her undergraduate degree at the University of California, Los Angeles, she came to UMD in the early 1990s to pursue her doctorate, pausing while she had kids and resuming under adviser Michael A’Hearn, who led 2005’s Deep Impact comet mission. She initially worked at NASA’s Goddard Space Flight Center in Greenbelt, focusing on planetary astronomy research. After moving to NASA headquarters in Washington, DC., she pivoted to managing the Near-Earth Object Observations Program, and in mid-2024, she stepped in to lead NASA’s Planetary Defense Coordination Office.
The asteroid 2024 YR4 in January 2025 as viewed by one of the largest telescopes in NASA’s Planetary Defense network.
Kelly Fast M.S. ’93, Ph.D. ’05
NASA’s Acting Planetary Defense Officer
Most of the solar system’s estimated 1.4 million asteroids are concentrated within the belt between Mars and Jupiter, but they occasionally get knocked off orbit and swing toward the inner planets. Miles-long objects, like what took out T. rex and company, aren’t the main concern; they’re rare and easier to spot. And little ones that make pretty shooting stars as they harmlessly disintegrate in Earth’s atmosphere or even slightly larger ones that result in fireballs don’t affect the planet’s surface. Instead, NASA is tasked with focusing on those in between, particularly 140 meters and larger that are tricky to spot amid many different orbits, which could flatten a state or a small country.
Her work frequently reconnects her with her alma mater; the successful 2022 Double Asteroid Redirection Test (DART) mission, humanity’s first attempt to alter a celestial body’s orbit, included UMD researchers, and NASA’s Planetary Data System Small Bodies Node, which archives spacecraft data about comets and asteroids and supports IAWN coordination, is based at UMD’s astronomy department. “UMD is such a key part of NASA data activity,” she says.
She’s looking forward to the launch of NASA’s NEO Surveyor mission, which will be the first infrared space telescope specifically designed to find near-Earth objects, giving scientists the ability to detect darker asteroids as well as to provide a better view closer to the direction of the sun, which can obscure objects for ground-based telescopes.
Ultimately, “an asteroid impact is a very rare event,” Fast says. “Other natural disasters happen all the time, but this is the only one we could potentially prevent.”