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by Ian J. O’Neill, Karen Fox, Charles Blue
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NASA
The asteroid Dimorphos was captured by NASA’s DART mission simply two seconds earlier than the spacecraft struck its floor on Sept. 26, 2022. Observations of the asteroid earlier than and after impression counsel it’s a loosely packed “rubble pile” object. Credit score: NASA/Johns Hopkins APL
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The asteroid Dimorphos was captured by NASA’s DART mission simply two seconds earlier than the spacecraft struck its floor on Sept. 26, 2022. Observations of the asteroid earlier than and after impression counsel it’s a loosely packed “rubble pile” object. Credit score: NASA/Johns Hopkins APL
After NASA’s historic Double Asteroid Redirection Check, a JPL-led research has proven that the form of asteroid Dimorphos has modified and its orbit has shrunk.
When NASA’s DART (Double Asteroid Redirection Check) intentionally smashed right into a 560-foot-wide (170-meter-wide) asteroid on Sept. 26, 2022, it made its mark in additional methods than one. The demonstration confirmed {that a} kinetic impactor may deflect a hazardous asteroid ought to one ever be on a collision course with Earth.
Now, a brand new research printed within the Planetary Science Journal reveals the impression modified not solely the movement of the asteroid but in addition its form.
DART’s goal, the asteroid Dimorphos, orbits a bigger near-Earth asteroid known as Didymos. Earlier than the impression, Dimorphos had a roughly symmetrical “oblate spheroid” form—like a squashed ball that’s wider than it’s tall. With a well-defined, round orbit at a distance of about 3,900 ft (1,189 meters) from Didymos, Dimorphos took 11 hours and 55 minutes to finish one loop round Didymos.
“When DART made an impression, issues obtained very fascinating,” mentioned Shantanu Naidu, a navigation engineer at NASA’s Jet Propulsion Laboratory in Southern California, who led the research.
“Dimorphos’ orbit is not round: Its orbital interval”—the time it takes to finish a single orbit—”is now 33 minutes and 15 seconds shorter. And the whole form of the asteroid has modified, from a comparatively symmetrical object to a ‘triaxial ellipsoid’—one thing extra like an rectangular watermelon.”
Dimorphos harm report
Naidu’s workforce used three knowledge sources of their pc fashions to infer what had occurred to the asteroid after impression. The primary supply was aboard DART: The spacecraft captured photos because it approached the asteroid and despatched them again to Earth by way of NASA’s Deep House Community (DSN). These photos supplied close-up measurements of the hole between Didymos and Dimorphos whereas additionally gauging the scale of each asteroids simply previous to impression.
The second knowledge supply was the DSN’s Goldstone Photo voltaic System Radar, positioned close to Barstow, California, which bounced radio waves off each asteroids to exactly measure the place and velocity of Dimorphos relative to Didymos after impression. Radar observations shortly helped NASA conclude that DART’s impact on the asteroid significantly exceeded the minimal expectations.
This illustration reveals the approximate form change that the asteroid Dimorphos skilled after DART hit it. Earlier than impression, left, the asteroid was formed like a squashed ball; after impression it took on a extra elongated form, like a watermelon. Credit score: NASA/JPL-Caltech
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This illustration reveals the approximate form change that the asteroid Dimorphos skilled after DART hit it. Earlier than impression, left, the asteroid was formed like a squashed ball; after impression it took on a extra elongated form, like a watermelon. Credit score: NASA/JPL-Caltech
The third and most important supply of knowledge is floor telescopes world wide that measured each asteroids’ “mild curve,” or how the daylight reflecting off the asteroids’ surfaces modified over time. By evaluating the sunshine curves earlier than and after impression, the researchers may learn the way DART altered Dimorphos’ movement.
As Dimorphos orbits, it periodically passes in entrance of after which behind Didymos. In these so-called “mutual occasions,” one asteroid can solid a shadow on the opposite or block our view from Earth. In both case, a short lived dimming—a dip within the mild curve—will likely be recorded by telescopes.
“We used the timing of this exact sequence of light-curve dips to infer the form of the orbit, and since our fashions had been so delicate, we may additionally work out the form of the asteroid,” mentioned Steve Chesley, a senior analysis scientist at JPL and research co-author. The workforce discovered Dimorphos’ orbit is now barely elongated or eccentric.
“Earlier than impression,” Chesley continued, “the occasions of the occasions occurred frequently, displaying a round orbit. After impression, there have been very slight timing variations, displaying one thing was askew. We by no means anticipated to get this sort of accuracy.”
The fashions are so exact that they even present that Dimorphos rocks backwards and forwards because it orbits Didymos, Naidu mentioned.
Extra info:
Shantanu P. Naidu et al, Orbital and Bodily Characterization of Asteroid Dimorphos Following the DART Impression, The Planetary Science Journal (2024). DOI: 10.3847/PSJ/ad26e7
Journal info:
The Planetary Science Journal