NASA’s Asteroid Deflection Experiment Yields Surprising and Mysterious Outcomes

Following the collision of NASA’s spacecraft with an asteroid, its orbit is expected to change gradually next month, leaving astronomers puzzled.

In 2022, the Double Asteroid Redirect Test (DART) sent a nearly 600-kilometer spacecraft towards a small asteroid known as Dimorphos.

Prior to the collision, Dimorphos completed an orbit every 11 hours and 55 minutes. Observations soon indicated that the impact shortened this orbital period by approximately 30 minutes, although in the following weeks and months, the orbital period diminished by an additional 30 seconds.

Astronomers have proposed that this phenomenon might be due to the release of small debris during the impact, which could gradually cause energy loss and result in a reduced orbital path.

Recently, Harrison Agrusa and Camille Chattanette from the University of Côte d’Azur in Nice, France, asserted that debris ejection cannot solely explain the observations.

“The boulders can be flung by Dimorphos, leading to a wider dispersion. This momentum will eventually revert and be transferred back to Dimorphos,” Agrusa explains.

Agrusa theorizes that a more plausible reason for Dimorphos’ shifting trajectory is that its impact affects its rotation in a complex manner, causing rocks on its surface to shift. The friction generated by these rocks could lead to heat production from their collisions. The resultant energy loss as heat might clarify the decrease in the asteroid’s orbital path, although this study has not modeled that aspect.

“When you rearrange materials on a surface, you’re altering the gravitational potential energy of Dimorphos itself,” Agrusa states. “This adjustment could feasibly slow down the orbital period within a month, as this would be a prolonged process.”

This highlights the challenges in predicting how asteroid orbits will alter post-impact, yet according to Agrusa, this phenomenon is less concerning when deflecting an asteroid heading towards Earth. This is because binary asteroid systems like Didymos and Dimorphos are quite uncommon, making it unlikely that similar effects will occur for a solitary asteroid orbiting the Sun.