When NASA’s Double Asteroid Redirection Test spacecraft intentionally slammed into the asteroid Dimorphos in September 2022, the impact may have caused “global deformation” of the space rock, according to new research.
The goal of the DART mission was to carry out a full-scale test of asteroid deflection technology on behalf of planetary defense and to see whether a kinetic impact — like crashing a spacecraft into an asteroid at 13,645 miles per hour (6.1 kilometers per second) — would be enough to change the motion of a celestial object in space.
Dimorphos is a moonlet asteroid that orbits a larger parent asteroid known as Didymos. Neither pose a threat to Earth, but the double-asteroid system was a perfect target to test deflection technology because Dimorphos’ size is comparable to asteroids that could pose a threat to Earth.
Since the day of impact, astronomers have used data from ground-based telescopes to determine that the DART spacecraft did change Dimorphos’ orbital period — or how long it takes to make a single revolution around Didymos — by about 32 to 33 minutes. But another crucial piece of information needed to understand how to deflect asteroids that may be on a potential collision course with Earth in the future is the composition of space rocks.
Different types of asteroids that pose a threat — whether hard, stony asteroids or rubble piles, which are effectively loose piles of rock held together by gravity — would require different deflection techniques.
Using data from NASAâs Stratospheric Observatory for Infrared Astronomy (SOFIA), Southwest Research Institute scientists have discovered, for the first time, water molecules on the surface of an asteroid. Scientists looked at four silicate-rich asteroids using the FORCAST instrument to isolate the mid-infrared spectral signatures indicative of molecular water on two of them.
The DART mission ended upon impact, but prior to colliding with Dimorphos, the spacecraft transmitted an incredibly detailed view of the little asteroid’s boulder-covered surface that is helping researchers learn more about how the space rock formed.
Astronomers were also able to carry out follow-up observations with ground- and space-based telescopes, and with the Italian LICIACube satellite that briefly followed the DART mission and imaged the aftermath for 5 minutes and 20 seconds.
The observations revealed that the impact unleashed a giant debris plume of material into space. Now, researchers have taken the investigation a step further by putting all this data into software to help answer key remaining questions, such as determining how the asteroid reacted to the collision and what kind of crater was left behind.
Rather than forming a simple crater on Dimorphos, the DART impact reshaped the entire asteroid, the results have suggested. A study describing the findings appeared Monday in the journal Nature Astronomy. The findings could prepare astronomers for what they will find when future missions fly by Dimorphos to better understand the effects of asteroid deflection technology.
Recreating the DART impact
A team of researchers modeled the impact using the Bern smoothed-particle hydrodynamics shock physics code to achieve their results. It’s “a computational tool designed to simulate impact events. Shock-physics codes in general are essential in the study of collisions and impact processes.
They incorporate various models, including material models and porosity models, to accurately represent the physical conditions during hypervelocity impact events, such as high pressures and temperatures,” said lead study author Dr. Sabina Raducan, postdoctoral researcher at the department of space research and planetary sciences at the University of Bern’s Physics Institute in Switzerland.
The software has been validated by replicating other impacts, including when Japan’s Hayabusa2 spacecraft punched a small copper impactor into the Ryugu asteroid in 2019.