For that reason, I'm not entirely sure that playing cosmic bowling with stuff floating around in the solar system is such a good idea ...
You're right that orbit determination is unstable over long runs, and very sensitive to initial conditions. But the good news is that the solar system is big. Most trajectories do not intersect with the earth's location. So perturbing an orbit that we think has a small chance of hitting us tends to be safe.
Also, of course, after deflection, any object is going to be monitored really closely for a long time.
Can we quantify how much Dimorphos’s new orbit has affected Didymos’s orbit? Is that calculable?
(I’ll also check out the GitHub repo you linked but I haven’t read it fully yet)
* What language is that software written in?
* What was the hardest problem you had to solve, while working on it?
The hardest problems are always the social ones. How do you get uptake of a new method, how do you get funding, how do you politely tell a collaboration they are doing the wrong thing, etc.
But if you mean pure technical stuff - the hardest problem I had to solve was rethinking some of the inner loops of the THOR algorithm. The problem was essentially to speed up a Hough transform in 6D space. Lots of time spent profiling CPU cache timings to get that fast.
But what about the other orbits that it interacts with, and every degree of interaction beyond that? I don't see why we should even be confident in estimating these effects past one or two degrees of separation.
Most of the objects interacting with each other have had millennia to settle into a balanced system - is it really so alarmist to think that a small perturbance to one rock could lead to unrecognizably subtle but strong effects on other rocks? And if two rocks smash into each other, then we've got a bunch of new smaller rocks to worry about.
Btw, there is an article on this topic that I posted to HN a while back but didn't get much attention - it's a good read though: https://nautil.us/should-we-really-be-messing-with-asteroid-...
Gravitational forces of asteroids on each other are negligible, other than the real biggies like Ceres, or binary systems right next to each other.
That article is a bit odd. For example, the claim that we only do asteroid discovery and not follow-up for orbital changes is absurd on its face. If an orbit changes then detection systems will perceive it as a new asteroid, and it will stop appearing in predicted locations. The broader point - that this is a technology with perhaps too much power, like what if nations shoot asteroids at each other, is a bit more valid but still far-fetched.
The other concerns of the article have more to do with different kinds of deflection (planetary, mining, intentional). While they're interesting topics with varying levels of risk (perceived or real) they don't really interact with the avoidance case.