The deliberate collision of Nasa’s Dart spacecraft with the asteroid moonbeam Dimorphos is estimated to have slid more than 1,000 tons of rock into space.
‘Ejecta’ from the collision at about 22,530 km/h changed Dimorphos’ orbit for about 33 minutes, according to new research presented during the Fall Meeting of the American Geophysical Union in Chicago.
History was made with the September collision, when humans first changed the course of a celestial body.
Nasa hoped to find out whether future Earth-threatening asteroids could be deflected by a deliberate collision and free the planet from potentially deadly impacts of the kind that once wiped out the dinosaurs.
The Dart, or Double Asteroid Redirection Test, was launched in November 2021 and has traveled for months to target Dimorphos, a companion asteroid to the larger Didymos traveling through space about 10.8 million miles from Earth.
The scientists used images from Dart’s lightweight Italian CubeSat (LICIACube) instrument for Imaging Asteroids, contributed by the Italian Space Agency (ASI), and new data on the composition of Dimorphos and the properties of the ejecta from telescope observations.
Based on the data, scientists can learn how much Dart’s first hit moved the asteroid, and by how much without recoil.
“We know the first experiment works. Now we can start applying that knowledge. Studying the eruption in the kinetic effect – all derived from Dimorphos – is an important way to learn more about the nature of its surface,” said Andy Rivkin, co-head of the Dart research team at the Johns Hopkins Applied Physics Laboratory. .APL).
The research also revealed that Dimorphos and Didymos had a similar structure and were made of the same material.
Predicting momentum transfer will be central to planning a future kinetic impactor mission, including estimating the size of the crashing spacecraft, the scientists said.
Nasa said it would also help determine the lead time that would be needed to enable a small deviation to derail a potentially dangerous asteroid in the future.
In the new analysis, the space agency found that the momentum transfer to Dart was roughly 3.6 times greater than if the asteroid simply absorbed the spacecraft and produced no eruptions, suggesting that the eruption contributed more to moving the asteroid than the spacecraft did.
“Momentum transfer is one of the most important things we can measure, because that’s the information we’ll 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 would change an asteroid’s momentum is key to designing a mitigation strategy for a planetary defense scenario,” he added.