[spenczar5]

Cool to see! I spent a few years working on asteroid orbital dynamics too. What integrator are you using? Do you cover the weird stuff like Yarkovsky effects? That gets important for NEO impact risk, which is what I worked on.

Matt Holman's ASSIST (https://github.com/matthewholman/assist) struck me as a breath of fresh air, coming from openorb and its kin.

[ddahlen]

I wrote a custom implementation of the Radau integrator, its been heavily modified. I have a lot of additional physics, it supports the non-gravitational models that JPL Horizons defaults to, so diurnal yarkovsky at least. I've been using it to study dust and small object dynamics, as they get pushed around by the sun a lot.

It does an OK job for impactors, but the integrator is tuned heavily for performance, and the tolerance defaults are not great for impactors.

I match jpl horizons for apophis to a few km, they have a lot more intense earth gravitational model then I care to implement, and by default I only include the 5 heaviest main belt asteroids, they have many more. That was the sweet spot for accuracy vs speed for me, overall accuracy goal is less than a few km over a decade.

The goal is to be able to handle the huge influx of new asteroids that the catalog will have due to LSST and eventually NEO Surveyor (which I worked on for 3 years). Most systems I know have been throwing hardware at the problem, I tried to make fast and efficient enough software that we can use it on a laptop for 5-10 million asteroids.

[adgjlsfhk1]

You might want to try OrdinaryDiffEq.jl. As of last summer, we have really fancy radau methods that are arbitrary order, arbitrary tolerance (see https://arxiv.org/abs/2412.14362 for the paper)

[spenczar5]

That is very impressive - getting the nongravs is a lot of work.

Anything published on your integrator and its modifications?

One nice feature of ASSIST (from what I remember, its been a while) was that I could add in more perturbers and crank up the gravitational harmonics if I wanted to. It sounds like you support that too at least for perturbers?

[ddahlen]

Final edits of a paper at the moment, aim to submit next week. Perturbers are easy to add, though a little poorly documented at the moment. Additional physics right now are J2 of jupiter/sun/earth, and GR corrections for the sun and jupiter.

Biggest speed gain is that I have a custom SPICE reader that is multi-core friendly (I re-implemented a lot of the SPICE standard in rust), and it is used as the source for planet positions. Being able to skip planet integration leads to massive speedups.