DART<\/a>\u00a0(Double Asteroid Redirection Test), which launched on Nov. 23 out of\u00a0Vandenberg Space Force Base in California,\u00a0is NASA\u2019s first test of a kinetic impactor. This mission\u00a0will demonstrate asteroid deflection via kinetic impact. The goal is to collide with the target\u2014in this case, the moon Dimorphos in the Didymos asteroid system\u2014to see how the orbit changes.\u00a0It\u2019s a test run to understand how scientists could approach this problem should we find an asteroid on a collision course with Earth one day.<\/p>\n Thomas, an assistant professor of astronomy and planetary\u00a0and\u00a0lead of the DART Observations Working Group, was in California for the launch, which went as planned and the spacecraft is operating as expected. She and her international team have been working for years to obtain a precise pre-impact orbit of\u00a0Dimorphos, the satellite asteroid, around\u00a0Didymos, the primary asteroid in a near-Earth asteroid system.<\/p>\n Near-Earth, of course, is relative; the planet is in no danger from\u00a0Didymos. However, an asteroid heading toward Earth is possible, and scientists throughout the world are working on ways to identify these potential threats and\u00a0how\u00a0to\u00a0mitigate\u00a0them. If this mission goes according to plan,\u00a0this technique, called kinetic impact deflection,\u00a0could be an important piece of a planetary defense system.<\/p>\n \u201cDART is a critical next step for planetary defense,\u201d Thomas said. \u201cIt is,\u00a0on the surface,\u00a0a simple test, but we will not completely understand what will happen until we do it.\u201d<\/p>\n Using data from 2003,\u00a0when the satellite was discovered,\u00a0through early 2021,\u00a0the working group has\u00a0been able to precisely constrain the characteristics of the orbit and the position of\u00a0Dimorphos\u00a0in the orbit at the time of impact in fall 2022.\u00a0They take\u00a0repeated images of the same object, which shows\u00a0dips in brightness when the satellite passes in\u202ffront of or behind the primary.\u00a0The timing of these brightness dips, called mutual events, allows the scientists\u00a0to determine the orbital period of the satellite.<\/p>\n \u201cThis is essentially thinking of the satellite\u00a0Dimorphos\u00a0as a clock,\u00a0which\u00a0will return to its position in front of or behind\u00a0Didymos\u00a0at consistent intervals,\u201d Thomas said.\u00a0\u201cOur working group will begin observations again in the months prior to the DART impact. We want to have the most complete picture of the current orbit before we change it through impact.\u201d<\/p>\n The spacecraft has a long way to go before reaching the asteroids; Thomas said they expect a late September impact. Right now, the<\/p>\n team will finish a series of publications discussing what is known about the Didymos-Dimorphos system before impact. They\u2019ll start observing again June to get a final look at the asteroids prior to impact. After impact, they\u2019ll take a number of what is called lightcurve observations to measure the change in the orbital period of Dimorphos around Didymos.<\/p>\n That information allows them to compare this new orbital period after impact with what is known before impact to determine the amount of change.\u00a0Her team also will do observations of the time of impact itself from a small number of observatories to see how much material is thrown off the surface and take the opportunity to do as much as possible to understand the objects such as taking spectra to further study the composition.<\/p>\n It\u2019s an exciting opportunity for space exploration and the potential of this kind of interaction; this kind of mission has never been done before.<\/p>\n \u201cOn the surface, this is a fairly simple physics experiment, but the properties of the asteroid and how much material will be ejected from the surface will affect what happens during the impact,\u201d Thomas said. \u201cOur observations\u00a0will tell us a lot of information that we need to know should we need to plan for a kinetic impactor in the future.\u201d<\/p>\n Heidi Toth | NAU Communications <\/p>\n","protected":false},"excerpt":{"rendered":"![\"DART](\"http:\/\/in.nau.edu\/news\/wordpresst\/uploads\/sites\/153\/wp-content\/uploads\/2021\/11\/dart-next_thrusterstill.jpg\")
![\"DART](\"http:\/\/in.nau.edu\/news\/wordpresst\/uploads\/sites\/153\/wp-content\/uploads\/2021\/12\/20211124_launch-01.jpg\")
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\n(928) 523-8737 | heidi.toth@nau.edu<\/a><\/p>\n