If We Blow Up an Asteroid, It Might Put Itself Back Together

Re:If We Blow Up an Asteroid, It Might Put Itself Back Together by Someone on Saturday March 09, 2019 @01:30PM (#19347629)

To be able to hit a specific part of the asteroid, you either have to wait until it is very close, or you would need very good aim.

Also, there’s beam divergence (https://en.wikipedia.org/wiki/Beam_divergence). That has a theoretical lower limit (http://www.aml.engineering.columbia.edu/ntm/level1/ch02/html...). Reading https://www.reddit.com/r/askscience/comments/1ihca9/how_much..., that limit is about 1:3000, so a laser beam is at least 100 km wide at the earth-moon distance.

I guess you would want to start rotating that asteroid way earlier, and that you would want to hit asteroids smaller than that. That makes it practically infeasible (Given infinitely precise aim, you theoretically still would be able to hit it only at one side, by aiming off-target, but that would wasting most of your beam energy)

Also, I am not convinced evaporating the surface by heating it from an angle would significantly impart angular momentum.

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Re:If We Blow Up an Asteroid, It Might Put Itself Back Together by 19870213 on Saturday March 09, 2019 @04:28PM (#19348602)

One of the asteroid redirection ideas is to have a probe with a laser evaporate part of the asteroid, the exhaust would then impart a force to nudge it off course. If caught earlier enough it's sufficient to prevent a collision with Earth.

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