Ever since NASA’s Double Asteroid Redirection Test (DART) spacecraft intentionally slammed into the small asteroid moon Dimorphos on September 26, disrupting its orbit in 33 minutes, the research team has been studying the implications of how this technique planetary defense might be used in the future, if needed at some point.
“Impacting the asteroid was just the beginning. We are now using the observations to study what these bodies are made of and how they formed, as well as how to defend our planet in case an asteroid is headed our way,” said Tom Statler, DART program scientist at the headquarters of NASA in Washington.
In the weeks following the impact, scientists turned their attention to measure the momentum transfer of the collisionof approximately 22,530 km/h from DART once morest its target asteroid.
Scientists estimate that the DART impact displaced a million kilograms of dusty rock into space, enough to fill six or seven train cars. The team is using that data, as well as new information regarding the asteroid’s small moon’s composition and ejection characteristics, thanks to telescope observations and from DART’s LICIACube images, contributed by the Italian Space Agency (ASI). ) to know how much the initial DART impact moved the asteroid and how much came from recoil.
“We know that the initial experiment worked. Now we can start applying this knowledge,” said Andy Rivkin, co-leader of the DART research team at the Johns Hopkins Applied Physics Lab (APL). “Studying the ejecta produced in the kinetic impact, all derived from Dimorphos, is a key way to gain more information regarding the nature of its surface.”
What is new that was discovered regarding Dimorphos?
Observations before and following the impact reveal that Dimorphos and its larger parent asteroid, Didymos, have a similar composition and are made of the same material, material that has been linked to ordinary chondrites, similar to the most common type of meteorite to impact Earth.
These measurements also took advantage of the Dimorphos ejecta, which dominated the reflected light from the system in the days following impact. Even now, the images of the telescopio del sistema Didymos show how solar radiation pressure has stretched the ejecta stream into a comet-like tail tens of thousands of kilometers long.
Putting those pieces together, and assuming Didymos and Dimorphos have the same densities, the team calculates that the impulse transferred when DART hit Dimorphos was approximately 3.6 times higher than if the asteroid had simply sucked in the spacecraft and produced no ejecta, indicating that the ejection helped move the asteroid more than the spacecraft.
Accurately predicting momentum transfer is critical to planning a future kinetic impact mission, should it ever be needed, as well as determining the size of the impacting spacecraft and estimating the lead time needed to ensure that a small deflection will move a potentially dangerous asteroid from its trajectory.
“Momentum transfer is one of the most important things we can measure, because it’s information we would need to develop an impactor mission to deflect a threatening asteroid,” said Andy Cheng, DART research team leader at Johns Hopkins APL. “Understanding how a spacecraft impact will change an asteroid’s momentum is key to designing a mitigation strategy for a planetary defense scenario.”
In Dimorphos ni Didymos have posed no danger to Earth before or following DART’s controlled collision with Dimorphos.
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Published: 12/17/2022
