NASA's DART spacecraft dislodged two million lbs of debris when it slammed into an asteroid

That information is "key to designing a mitigation strategy for a planetary defense scenario."
Chris Young
Illustration of NASA’s DART spacecraft
Illustration of NASA’s DART spacecraft

NASA/Johns Hopkins APL/Steve Gribben 

Earlier this year, NASA's DART spacecraft successfully crashed into an asteroid to demonstrate a planetary defense method that could one day be used to alter a large asteroid on a collision course with Earth.

Since the impact event occurred, scientists have observed an unexpected double tail on the target asteroid moonlet, Dimorphos, and carried out detailed analyses of the space rock.

Now, NASA scientists working on that research have released impressive new findings, including the estimation that Dimorphos jettisoned two million pounds (one million kilograms) of debris into space — enough to fill six or seven rail cars — after the impact.

DART displaced two million lbs of debris

The Double Asteroid Redirection Test (DART) spacecraft was launched last November. It then traveled through space for almost a year before slamming into the asteroid Dimorphos at 14,000 mph (22,500 km/h), on September 27.

The scientific community knew within a few weeks that the DART mission had been a success thanks to numerous observatories on the ground and in space training their instruments on the asteroid. Scientists calculated that the impact altered the asteroid's trajectory and shortened its orbit around its parent asteroid Didymos by 33 minutes.

Soon after, scientists also discovered a massive double tail coming off of Dimorphos. That tail is made up of debris from the impact flung into space, also known as ejecta. It measures a massive 6,000 miles (10,000 kilometers) in length. Follow-up observations have since revealed that DART displaced approximately two million pounds (roughly one million kg) of debris in this ejecta.

New DART findings could prove vital for planetary defense

According to NASA, this new information is vital in the context of momentum transfer. That's because their calculations show that the momentum transferred from the DART spacecraft to Dimorphos was around 3.6 times greater than if the asteroid had absorbed the spacecraft without producing ejecta. That means the ejecta played a key role in the shift in Dimorphos' trajectory.

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"Momentum transfer is one of the most important things we can measure, because it is information we would need to develop an impactor mission to divert a threatening asteroid," Andy Cheng, DART investigation team lead from Johns Hopkins APL explained in a NASA blog post. “Understanding how a spacecraft impact will change an asteroid’s momentum is key to designing a mitigation strategy for a planetary defense scenario."

In other words, studying this momentum transfer via the ejecta flowing from Dimorphos could one day save humanity in an asteroid collision scenario. That is, after all, why NASA slammed a roughly $300 million spacecraft into an asteroid at 14,000 mph in the first place.