DART Mission Success: Hubble Captures Time-Lapse Movie of Asteroid Impact Aftermath
NASA's Double Asteroid Redirection Test (DART) mission was a success. On September 26, 2022, the DART spacecraft made contact with Dimorphos, a small asteroid moon that orbits its parent asteroid, Didymos. Incredibly, the telescopes showed that Dimorphos' orbit was shortened by a whopping 33 minutes – more than 25 times the minimum requirement for mission success. Simultaneously, liberated debris created a tail that spanned more than 1,500 kilometers. For around three weeks, the team used the Hubble Space Telescope to observe the tail and discovered that its shape resembled that of “active asteroids”, which possess asteroid-like orbits and comet-like tails. This indicates that impacts are capable of “activating” asteroids.
Tony Farnham, co-author of the study, stated that prior to the impact they anticipated that the impact would only decrease Dimorphos' orbit by approximately 10 minutes. The impact caused the orbital period to be reduced by more than 30 minutes, making it shorter than the usual 12-hour orbit. In effect, the ejected material acted as a “jet” to push the moon farther away from its original orbit.
Set to launch in October 2024, the European Space Agency's Hera mission will be a revisit of the Didymos-Dimorphos system to assess the outcomes of the DART experiment further. The resulting crater is of particular interest. Cheng proposed that the crater could be so massive that it does not resemble a crater; DART might have removed a considerable portion of the affected side. A further inquiry relates to the rotation state of the object; before the impact, Dimorphos was gravitationally bound to Didymos, but the impact could have caused the asteroid to enter a state of chaotic tumbling. Hera shall look into this and any other unresolved queries.
The Hubble Space Telescope's time-lapse movie of the aftermath of the collision created a remarkable depiction of the changes that occurred as dust and pieces of the asteroid were thrown into space. Researchers are still studying the DART data, but their findings have already determined that the transfer of momentum from the DART spacecraft to Dimorphos was increased by the recoil from ejecta streams produced by the impact.
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