In 2022, NASA intentionally crashed an unmanned probe into a small asteroid. This small asteroid is actually in orbit around a larger asteroid, and the purpose of the test was to see if they could change the orbit by hitting it with a small spacecraft.
Based on subsequent observations, it appears the orbit was, in fact, changed.
“Dimorphos’ orbit is no longer circular: Its orbital period” – the time it takes to complete a single orbit – “is now 33 minutes and 15 seconds shorter. And the entire shape of the asteroid has changed, from a relatively symmetrical object to a ‘triaxial ellipsoid’ – something more like an oblong watermelon.”
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Not only did they prove they can intentionally crash a spacecraft into an asteroid, but they proved that such a crash can have a measurable effect. Also, the observations gave them information as to the makeup of these types of asteroids, which seem to be very loosely held together, for instance.
All of this means that if, one day, astronomers detect an asteroid headed for collision with the Earth, then we can do something about it. If it is detected early enough, then all we have to do is nudge it a little, to make it miss.
Here is a 13-minute YouTube video on this, which some readers here may find interesting.
_ Pete