NASA’s Impact on Didymos System
Credit: Steve Gribben/Johns Hopkins University APL/NASA
For the first time in history, humanity successfully altered the orbit of an asteroid around the sun. This groundbreaking achievement was made possible by NASA’s Double Asteroid Redirection Test (DART) mission conducted in 2022, with its effectiveness now being assessed.
DART targeted a small asteroid named Dimorphos, which orbits a larger asteroid called Didymos. The spacecraft was designed to collide with Dimorphos to test the kinetic impactor method, exploring whether this technique is a viable way to change an asteroid’s trajectory, particularly if one were to threaten Earth.
The mission proved to be a resounding success, reducing Dimorphos’ orbital period by 32 minutes. Astronomers have been monitoring the asteroid system closely since then, collecting approximately 6,000 observations. These efforts revealed a slowdown of about 11.7 micrometers per second in the overall orbit, equivalent to approximately 40 millimeters per hour. This change is projected to reduce the orbital radius by around 360 meters.
“While it may not sound significant, the concept of dynamic effects suggests that early impacts can lead to substantial changes over time,” says Rahil Makadia of the University of Illinois at Urbana-Champaign, a member of the asteroid monitoring team. “Though this number seems small, its accumulation over decades can have a considerable impact.”
The observed slowdown resulted from two main factors: the initial impact of the spacecraft and a secondary thrust caused by debris ejected from Dimorphos’ surface. Makadia and his colleagues determined that these two effects were roughly equivalent, allowing for accurate calculations of the asteroid’s mass and density. Dimorphos is approximately half as dense as Didymos, supporting the hypothesis that it is a rubble pile formed from material ejected during Didymos’s rotation.
This groundbreaking data can be invaluable in future efforts to redirect potentially hazardous asteroids. “We now possess a solid foundation for predicting the outcomes of future dynamic collision missions,” states Makadia. Additionally, the European Space Agency’s Hera spacecraft, en route to Didymos and scheduled to arrive in November, is expected to provide even more precise measurements, enhancing our ability to safeguard Earth from incoming asteroid threats.
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Source: www.newscientist.com
