Time for the Oct. Astronomical Journal (vol. 170 #4):
Wang, B. Duan, X. Huang, F. et al. Simulation Analysis of Kinetic Impact Effects on Near-Earth Asteroid Defense Mission Using Precise Orbit Determination 224 adfc5c
Ingebretsen, C. Bolin, B. T. Jedicke, R. Apache Point Rapid Response Characterization of Primitive Imminent Impactor 2024 RW1 237 adfb63
There isn’t a single asteroid, type of asteroid, or category of asteroid types. So how would we gauge the success or failure of a deflection attempt of an Earth impactor? If we didn’t fully deflect the NEO from Earth by a first attempt, the second strike likely needs to be fast. The observing arc can’t be long after the first blow, so the (re)assessment of the asteroid’s orbit must be very precise. Wang et al. run through the exercise: given some DART-like deflection mission, and some plausible space telescope launched to observe the collision, what precision can we get, and is it enough to settle “deflected” vs. “only partially deflected”? They conclude that, yes, it is within our technology to fly both DART, and a sufficient assessment telescope. Well within.
Of course, a sufficiently-small asteroid wouldn’t be deflected at all- it would break up in our atmosphere. Last year, asteroid 2024 RW1 was discovered less than 12 hours before Earth impact. (It hit over the Pacific, so unfortunately we got no meteorites.) An Apache Point telescope swung into place, rapidly studying RW1. Here, Ingebretsen et al. give their procedures and results. In that 12 hours, the NEO was seen to be small (few meters- likely 3), a carbonaceous chondrite (likely B-type), a fast rotator (~half hour), etc. Too bad, getting pieces of that would’ve been nice.