In the current (4 Oct) issue of New Scientist:
www.newscientist.com/article/2498319-nasas-asteroid-deflection-test-had-unexpected-and-puzzling-outcome/
Alex Wilkins 1 October 2025 NASA’s asteroid deflection test had unexpected and puzzling outcome
As one might expect from New Scientist, this is an accessible take on a scientific work. The original subject is the post-impact assessment of the DART experiment- how effective was a given impactor spacecraft at the task of deflecting a small asteroid from its original trajectory? The impact made a bigger splash than expected, literally. The factor “beta” (enhancement, or additional momentum) was greater than 1, significantly greater, because material sprayed out by the collision acted as a crude thruster, pushing Dimorphos in addition to DART proper. But even more unexpected: after the impact and ejecta spray, the orbit of Dimorphos kept changing slightly.
Yes, the space environment is weird. On Earth, air resistance and other factors tend to dampen or erase secondary and tertiary effects. But in space, an inertial environment, such things become noticeable. It is for reasons like this that we actually do tests like this: things are not as simple as they seem, and we can’t just assume. Our assumptions are based on our life experiences, and those experiences were all on Earth. Doubters and backseat drivers take heed.