The DART mission, which involved a spacecraft deliberately colliding with the 170-meter (560-foot) asteroid Dimorphos on September 26, 2022, has proven that kinetic impact can effectively modify the trajectory of a potentially hazardous asteroid. A paper in the Planetary Science Journal reveals that this 'groundbreaking' event resulted not only in a change in the asteroid's motion but also in its physical structure.
Previously, Dimorphos, which orbits the larger asteroid Didymos, had a symmetrical oblate spheroid shape and a well-defined circular orbit. The impact has transformed Dimorphos into a "triaxial ellipsoid," likened to an oblong watermelon, and shortened its orbital period around Didymos by 33 minutes and 15 seconds.
"The impact of DART on Dimorphos has been fascinating," stated Shantanu Naidu, a navigation engineer at JPL who led the study. He explained that the asteroid's orbit has become more eccentric, indicating a notable departure from its original circular path.
The study utilized data from three primary sources: images captured by the DART spacecraft, radar observations from the Goldstone Solar System Radar, and global telescopic observations of the asteroids' light curves. These comprehensive datasets have allowed scientists to precisely determine the changes in Dimorphos' orbit and shape.
Following the impact, Dimorphos experienced an immediate reduction in the average distance to Didymos, with its orbital period decreasing by over half an hour. The study's detailed models also revealed the asteroid's dynamic behavior, including a rocking motion as it orbits.
"This study corroborates other research, reinforcing our understanding of asteroids and the effectiveness of kinetic impact as a planetary defense strategy," commented Tom Statler, NASA's lead scientist for solar system small bodies. The findings suggest Dimorphos resembles a "rubble pile" asteroid, similar in composition to asteroid Bennu.
Looking ahead, the European Space Agency's Hera mission is set to further examine the aftermath of the DART impact, offering a closer look at the modified asteroid and the debris field.
Research Report:Orbital and Physical Characterization of Asteroid Dimorphos Following the DART Impact
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