NASA’s DART mission rendezvoused and collided with the smaller asteroid Dimorphos, a moon of the larger asteroid Didymos, almost a year ago. The aim was to move the asteroid to a different orbit. This goal was achieved and the asteroid displaced much further than expected. New research suggests that the orbit continued to inexplicably change for a month after the impact.
DART is a planetary defense system known as a kinetic impactor. This approach is designed to hit a celestial body at high speed. The change in momentum caused by the striking object changes the orbit of the asteroid. If the asteroid is on a collision course with Earth, this could shift the object to a safer route. The change is usually small, but given enough time it may be enough to be safe.
Dimorphos did not pose a danger to our planet. This asteroid was chosen because astronomers knew how long it took for Didymos to orbit around it. DART showed that an impact could change an asteroid’s speed and even moved Dimorphos into a smaller orbit. The aim was to shorten the time by seven minutes, but the coup actually shortened the time by 33 minutes, at least at first. Afterwards, the asteroid somehow continued to lose momentum over time.
Discovery of high school students
A group of high school students from the Thacher School conducted observations of the asteroid until November 6, 2022, before the impact. Using the 0.7-meter telescope at the school’s observatory, they measured the period of Dimorphos and found that it continued to increase in the days after the collision, becoming higher than the official measurement immediately after the collision.
The teacher and director of the observatory, Dr. “The number we got was slightly more, with a change of 34 minutes,” Jonathan Swift told New Scientist. “This was disturbingly inconsistent.”
This behavior was unexpected, but it was the first time humanity had literally moved a celestial body. The impact is believed to have created a crater tens of meters in diameter on the asteroid, a huge impact for an object only 160 meters in diameter.
The impact threw copious amounts of material, including many rocks, into orbit. It may be possible for some of these to return to Dimorphos, slowing him down even further.
Dr. from Northern Arizona University. “If you hit a pile of debris with the spacecraft, a lot of material would be ejected and fly away from the object,” Cristina Thomas said in a previous interview. We see this in our first images after the collision. This thrown material carries momentum. “The period change we observe is not only the result of momentum transfer from the impacting spacecraft, but also the extra momentum increase resulting from the motion of the ejected material,” he said.
The European Space Agency’s Hera mission will reach the asteroids in late 2026 and provide more information about the impact and its consequences. So far the orbit appears to be stable.
The young researchers presented their work in June at the American Astronomical Society in Albuquerque and in a paper accepted for publication by the American Astronomical Society.
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