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In 2022, NASA\u2019s DART (Double Asteroid Redirection Test) spacecraft collided with an object named Dimorphos. The objective was to test redirecting hazardous asteroids by deflecting them with an impact. The test was a success, and Dimorphos was measurably affected. <\/p>\n
Follow-up research shows that Dimorphos was more than deflected; it was deformed. <\/p>\n
<\/p>\n In recent decades, we\u2019ve made progress cataloguing the asteroids in the Solar System. Some of them are close enough to Earth to be dangerous. If an object comes within 1.3 astronomical units of the Sun, it\u2019s called a Near Earth Object (NEO.) If it\u2019s more than 140 meters (460\u00a0ft) across and crosses Earth\u2019s orbit, it\u2019s called a Potentially Hazardous Object (PHO.) Over 99% of NEOs and PHOs are asteroids, and the remainder are comets.<\/p>\n Earth has suffered many impacts from these objects in the past. The most famous impactor was Chicxulub. When it struck Earth about 65 million years ago, it was responsible for the end of the dinosaurs. <\/p>\n Now that we know the danger these tumbling space rocks pose, NASA and other agencies are preparing to do something about it. DART was a test mission to see how effective a simple kinetic impactor could be at changing the trajectory of an asteroid. <\/p>\n Dimorphos doesn\u2019t pose any threat to Earth. It was chosen as the test target because it\u2019s actually one part of a pair of objects. Dimorphos is a tiny moon of an asteroid named 65803 Didymos. Because Dimorphos is in orbit around Didymos, it\u2019s easy to measure changes in the object\u2019s movement after the impact. <\/p>\n An entire team has been following Dimorphos since DART impacted it to track how the object\u2019s orbit has changed. Their observations show that the test was a success. Dimorphos\u2019 orbit around Didymos was shortened by 32 minutes when the objective was to shorten it by only 73 seconds. Interestingly, it wasn\u2019t the impact that affected Dimorphos\u2019 orbit; it was because of the recoil effect from the ejected debris.<\/p>\n New research published in The Planetary Science Journal shows that Dimorphos was more deeply affected by the impact than thought. The paper is titled \u201cThe Dynamical State of the Didymos System before and after the DART Impact.\u201d The lead author is Derek Richardson from the Department of Astronomy at the University of Maryland. Richardson is the team leader for one of the DART investigation teams called the Dynamics Working Group. <\/p>\n \u201cFor the most part, our original pre-impact predictions about how DART would change the way Didymos and its moon move in space were correct,\u201d said Richardson. \u201cBut there are some unexpected findings that help provide a better picture of how asteroids and other small bodies form and evolve over time.\u201d<\/p>\n Pre-impact observations showed that Dimorphos had an oblate shape. But after the impact, it became prolate or elongated. This went against pre-impact observations, which suggested that Dimorphos was initially elongated.<\/p>\n DART had a mass of 610 kilograms (1,340 lb) and struck Dimorphos at a speed of about 21,000 km\/h (13,000 mp\/h). The impact had a force equivalent to about three tons of TNT exploding and unexpectedly altered Dimorphos\u2019 shape. <\/p>\n \n