The DART spacecraft displaced a thousand tons of rock when it collided with the Dimorphos asteroid

The DART spacecraft disrupted the orbit of Dimorphos in a collision that displaced a thousand tons of rock into space.


The impact of the DART spacecraft that disrupted the orbit of the Dimorphos asteroid displaced more than a thousand tons of rock into space, enough to fill 6 or 7 freight train cars.

Ever since NASA’s Double Asteroid Redirection Test ( DART ) spacecraft intentionally collided with the lunar asteroid Dimorphos on September 26, disrupting its orbit in 33 minutes, the research team has been studying the implications of how this technique could be used. of planetary defense in the future, should the need ever arise. This has included further analysis of the “ejecta” – the many tons of asteroidal rock displaced and hurled into space by the impact – whose recoil substantially increased the DART ‘s thrust against Dimorphos .

Continued observations of the evolving ejecta have allowed the research team to better understand what the DART spacecraft accomplished at the impact site. Members of the DART team have offered a preliminary interpretation of their findings during the Fall Meeting of the American Geophysical Union in Chicago.

“What we can learn from the DART mission is part of NASA ‘s overall work to understand asteroids and other small bodies in our Solar System,” Tom Statler, DART program scientist at NASA Headquarters in Washington , said in a statement. , and one of the speakers at the briefing. “The asteroid impact 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.”

Central to this effort is detailed post-impact scientific and engineering analysis of data from the world’s first demonstration of planetary defense technology. In the weeks after the impact, scientists focused on measuring the momentum transfer from the DART ‘s collision with its target asteroid at approximately 14,500 miles per hour.

Scientists estimate that the DART impact displaced more than 1,000 tons of dusty rock into space, enough to fill six or seven rail cars. The team is using this data – as well as new information on the asteroid’s moon composition and ejecta characteristics, obtained from telescopic observations and images from the Lightweight Italian CubeSat for Asteroid Imaging (LICIACube) , provided by the Italian Space Agency (ASI) – to find out how much the initial impact of the DART moved the asteroid and how much was due to 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 Laboratory (APL). “Studying the ejecta produced in the kinetic impact – all of them derived from Dimorphos – is a key way to obtain more information about the nature of their surface.”

Pre- and post-impact observations reveal that Dimorphos and its largest asteroid , Didymos, are similar in constitution and composed of the same material, material that has been linked to ordinary chondrites, similar to the most common type of meteorite to impact. against Earth. These measurements also took advantage of the ejecta from Dimorphos , which dominated the reflected light from the system in the days after impact. Even now, telescopic images of the Didymos system show how solar radiation pressure has stretched the ejecta stream into a comet-like tail tens of thousands of kilometers long.

The ejected material contributed to move the asteroid

Putting all these pieces together and assuming that Didymos and Dimorphos have the same densities, the team calculates that the momentum transferred when DART collided with Dimorphos was roughly 3.6 times greater than if the asteroid had simply sucked in the spacecraft and produced no ejecta at all. indicating that the ejecta contributed to moving the asteroid more than the ship.

Accurately predicting momentum transfer is critical to planning a future kinetic impact mission, should it ever be necessary, including determining the size of the impacting spacecraft and estimating the amount of time required to ensure that a small deflection deflects a potentially dangerous asteroid from its trajectory.

“Momentum transfer is one of the most important things we can measure, because it’s the information we would need to develop an impactor mission to deflect a threatening asteroid ,” said Andy Cheng, head of the Johns Hopkins APL DART research team. “Understanding how a spacecraft impact will change an asteroid ‘s momentum is key to designing a mitigation strategy for a planetary defense scenario.”

Neither Dimorphos nor Didymos pose any danger to Earth before or after DART ‘s controlled collision with Dimorphos.