2023-09-12 01:45:43
▲ Hubble telescope observation image showing some debris regarding a day following NASA’s Dart spacecraft crashed into Dimorphos / Photo = NASA, ESA, STScI, J. Li (PSI) Almost a year ago, the National Aeronautics and Space Administration (NASA) The Dimorphos asteroid, which intentionally collided with the ‘Double Asteroid Orbit Correction Test’ (DART) spacecraft, is showing unexpected movement.
According to the British science media New Scientist, a joint U.S. and British research team discovered that the Dimorphos asteroid was moving unexpectedly during more than a month of observation following colliding with the Dart spacecraft in September of last year. This might also have implications for future missions to protect the Earth from these near-Earth asteroids that are at risk of hitting the Earth.
NASA used an asteroid called Dimorphos, which is relatively safe and easy to observe, as a spacecraft collision test target to see if it was possible to change the orbit of an asteroid that might collide with Earth. This is because this asteroid is bound by the gravity of its parent asteroid, Didymos, and revolves around it, just as the moon orbits the Earth. The goal of the Dart mission was to shorten Dimorphos’ orbit by regarding 12 hours. ▲ A few minutes following the intentional collision of NASA’s Dart spacecraft with the target asteroid Dimorphos captured on September 26, 2022 (local time) Image captured by the Italian Space Agency’s small satellite LICIACube. / Photo = ASI/NASA The test was successful. This is because the orbital period of Dimorphos, which collided with the Dart spacecraft that flew at a speed of Mach 18.4 (22,530 km per hour, 6.25 km per second), was shortened by 33 minutes.
However, when Jonathan Swift, a teacher at Thatcher School in California, and his students observed Dimorphus using the school’s 0.7-meter astronomical telescope, the orbital period was found to be one minute shorter.
“The number we observed was a bit more variable at 34 minutes,” Swift told New Scientist. He and his research team of students presented these research results at the American Astronomical Society meeting held in New Mexico, USA, last June, and received positive responses from other astronomers.
Observations showed that Dimorphos’ orbit continued to change following the collision. But the reason is unclear. One possibility is that the asteroid is breaking up now, not before. ▲ A James Webb Space Telescope observation image showing the Dart spacecraft crashing into the asteroid Dimorphus. / Photo = NASA, ESA, CSA and STScI. Harrison Agrussa of the Côte d’Azur Observatory in France, who participated in the NASA Dart study, said there is some evidence for this shortening of the orbital period. “It (Dimorphos) was quite free following the collision,” he explained. This means that just as the Moon is shaking relative to the Earth, Dimorphos is also shaking relative to Didymos. “This might develop into more chaotic tumbling, which might cause the asteroid to spin,” Agrusa said, but “it is unlikely that such tumbling will shorten Dimorphus’ orbital period.” The trajectory in tumbling actually changes randomly.
“It is more likely that the impact left rocky material, including several meter-sized boulders, in orbit around Dimorphos,” Agrusa said. “Then these might fall back to the asteroid’s surface, further reducing its orbital time,” he said. “This is the most likely explanation.”
Nancy Chabot of the Johns Hopkins Applied Physics Laboratory in Maryland, who led NASA’s Dart research, said the Dart research team has continued to observe Dimorphos and plans to announce its results in the coming weeks. “We are very excited to see what we have done with Dimorphos,” he said of this observational study by another research team. “These specific, detailed observations are really important for using this technology if we need it in the future.”
The European Space Agency’s (ESA) Hera observation spacecraft will reach Dimorphos in 2026. This will clearly show us what happened following hitting this asteroid.
Reporter Taehee Yoon [email protected]
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