For over five decades, Richard Binzel has been diligently tracking potentially hazardous asteroids, peering into the vastness of space for celestial threats to our planet. His dedication to this task led him to develop the Torino scale, a system that rates the potential danger of near-Earth objects (NEOs) based on their likelihood of hitting Earth and the potential devastation such an impact could cause.
In early 2023, asteroid 2024 YR4 briefly reached level 3 on this scale – the highest rating for a space rock in two decades – momentarily igniting public concern about an impending cosmic catastrophe. While 2024 YR4 ultimately proved to be a false alarm, Binzel, a planetary scientist at MIT, assures us that such dramatic events are extremely rare and likely won’t escalate into catastrophic scenarios during our lifetime or even our grandchildren’s.
Binzel spoke with New Scientist about the challenges and rewards of asteroid hunting, the true odds of a devastating impact, and the future of planetary defense – an increasingly critical field as we become better at spotting these potentially hazardous visitors from space.
From Public Curiosity to Scientific Concern:
When Binzel began his career in the 1970s, public perception of asteroids differed greatly from today’s awareness. He worked with pioneering geologist Eugene Shoemaker, who understood that Earth’s impact craters were remnants of ancient asteroid collisions. While this scientific understanding was developing, public interest remained largely dismissive.
“It was a giggle factor,” Binzel recalls. However, the discovery of the K-T boundary layer in 1980 – geological evidence pointing to the Chicxulub asteroid impact that wiped out the dinosaurs – served as a wake-up call for scientists and the general public alike. This shift in awareness spurred initiatives like the book Cosmic Catastrophes by Clark Chapman and David Morrison, which aimed to educate the public about the real threat posed by asteroids.
Creating a Language for Risk:
Motivated by the need for clear communication regarding potential asteroid impacts, Binzel developed the Near-Earth Object Hazard Index – later renamed the Torino scale – in the 1990s. This system uses a straightforward 0 to 10 rating to convey an object’s probability of hitting Earth and its potential destructive impact.
Initially met with resistance from some astronomers who felt it overly simplistic, Binzel persevered. He argued that the scale would provide crucial information to both scientists and the public in a readily understandable manner. Today, the Torino scale is universally recognized as the go-to method for communicating asteroid threat levels.
The True Odds of an Impact:
While headlines occasionally trumpet potential asteroid dangers, Binzel emphasizes that we are far from being overwhelmed by space rocks. He likens the low-end risk to minor earthquakes – events that may shake things up locally but pose no major threat to civilization.
“The vast majority of objects discovered will turn out to be non-threatening,” he explains. “They’ll either move on safely or we’ll get enough data to rule them out completely.” The discovery rate for NEOs is rapidly increasing thanks to advanced telescopes like the Vera C. Rubin and the Near-Earth Object (NEO) Surveyor, slated to launch soon. These powerful instruments will significantly bolster our ability to identify potentially hazardous asteroids well in advance of any potential impact.
DART: A Turning Point:
The success of NASA’s Double Asteroid Redirection Test (DART) mission in 2022 – where a spacecraft deliberately collided with an asteroid, successfully altering its trajectory – represents a momentous leap forward for planetary defense. It demonstrates humanity’s capability to directly intervene and mitigate the risk posed by incoming asteroids.
The Moral Imperative:
Despite the reassuring advancements in our understanding and preparedness, Binzel stresses that complacency is not an option.
“If we were to be caught off guard by a serious threat tomorrow because we didn’t have the right telescope ten years ago, it would be an epic failure of science,” he declares. Binzel urges continuous investment in asteroid surveys and tracking technologies as our moral obligation to safeguard Earth from potential cosmic dangers.
