Astronomers from the University of Hawaiʻi Institute for Astronomy (IfA) captured a historic moment of impact on Monday, September 27 as NASA sent a 1,260-pound box-shaped spacecraft head-on into a non-threatening asteroid during a planetary defense exercise. NASA’s Double Asteroid Redirection Test (DART) confirmed the space agency can successfully navigate a spacecraft to intentionally collide with and deflect an asteroid from its current path.
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IfA operates the NASA-funded Asteroid Terrestrial-impact Last Alert System or ATLAS, which captured images taken every 40 seconds from the time of impact and shows the plume of dust blown off of the asteroid by the impacting DART spacecraft.
The state-of-the-art asteroid alert system is a four telescope system located in the northern hemisphere atop Haleakalā and Maunaloa and in the southern hemisphere in South Africa and Chile. ATLAS’ telescope in South Africa compiled images of Monday’s planetary defense technology demonstration.
“The ATLAS telescope system was well positioned to observe the impact from Earth, and we were fortunate to have excellent weather at the ATLAS telescope at Sutherland, South Africa,” said IfA Astronomer Larry Denneau, an ATLAS co-principal investigator.
“Our robotic operation and automatic data processing were able to produce measurements minutes after each observation, giving scientists immediate feedback about the observable effects of the impact.”
Asteroid impact early warning system
The ATLAS system can provide one day’s warning for a 20-meter diameter asteroid, capable of city-level destruction. Since larger asteroids can be detected further away, ATLAS can provide up to three weeks’ warning for a 100-meter asteroid, capable of wide regional devastation.
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“The DART mission struck the little moon of Didymos named Dimorphos hard enough to reduce its orbital period from 12 hours by about 5 minutes. Therefore the eclipses we can observe from Earth will occur earlier and earlier, and after a week or two we will have a very good measurement of how much Dimorphos recoiled after being struck by DART,” said John Tonry, IfA professor and ATLAS principal investigator. “Given this new information, it will be possible to plan a mission to divert a dangerous asteroid: how early must it be struck, how massive must the spacecraft be, how fast must it be traveling.”
Observations on Maunakea
More images of the headline-topping impact were captured atop Maunakea at the Canada-France-Hawaii Telescope. IfA Astronomer Richard Wainscoat and University of Western Ontario astronomer Robert Weryk obtained images of the dust plume using the world-class optical telescope about 13 hours after the DART spacecraft impacted Dimorphos.
“The extent and structure of the dust plume surprised me,” said Weryk. “I was expecting it to be on a much smaller scale.”
Throughout the next couple of months, IfA astronomers will work with students to study Dimorphos’ orbit using the UH88 telescope on Maunakea and Faulkes North telescope on Haleakalā, which is one of a number of observatories part of the Las Cumbres telescope network.