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ericthefred t1_iqy2y0t wrote

Reply to comment by JagerBaBomb in After DART: Using the first full-scale test of a kinetic impactor to inform a future planetary defense mission by EricFromOuterSpace

Depends. Can you fill in the following unknowns for the mathematicians?

  1. How much energy went into changing the spin of the asteroid rather than its orbit
  2. How much energy was redirected sideways by the potential initial collision with a non-perpendicular surface?
  3. How much energy went into blasting loose material in all directions like a cue ball hitting a racked set of pool balls, multiplied by how many thousands or millions or billions for the unknown number of pool balls in the equation?

Mathematicians need to have data to work with.

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SaltineFiend t1_iqyepz0 wrote

Also an object which ejects mass in space is known as a rocket engine. That ejecta plume was a rocket engine. It's a nonlinear equation that you have to run in real time to get a result. At the very instant you collide the two masses together the mass of the larger object changes.

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ericthefred t1_iqz4qg1 wrote

An excellent point. When dealing with rockets, you have to account for the changing mass of the vehicle as propellant is exhausted. In order to integrate it into my list and remove the overlap with item 3 (being the part involving the energy in the ejecta), I would phrase it as: 4) How much mass has departed the asteroid?

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Crowbrah_ t1_iqzmjae wrote

At least a kilogram, but I could be wrong.

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