ddahlen

I refit the orbit and yeah this is not a dangerous object. Given its (currently poorly constrained) orbit it is likely a comet, it came the closest it will ever come to Earth last month at about half an AU from us. (IE: half the distance from the earth to the sun).

It is at about a 110 degree inclination, meaning it is basically perpendicular to the solar system plane and already passed perihelion.

MOID, or Minimum Orbital Intersection Distance, is a basic geometric measurement that says how close the geometric ellipses of two orbits get together. It doesnt mean that the objects will actually be that close ever. For example the MOID of the jupiter trojan asteroids is basically 0 since the orbits are the same, but they dont get close to jupiter. It's really handy to use it to rule out dangerous stuff though, non-zero MOID usually means there is no way it could ever be dangerous.

Here is some of the orbit code I used: https://github.com/dahlend/kete

Comment · 1 month ago

This is very niche, only for people who do astrophotography or astronomers, mostly because of the required specialized file format.

I have slowly built out a set of tools for asteroid orbits and photometry (measuring how bright stars/asteroids are).

It is very rough still (Desktop only), and it only supports the FITs file standard.

https://www.astrometry.space/

Basically it is a full professional grade telescope processing pipeline in your browser. It does 2 queries to some custom databases to identify known asteroids and stars, but all image processing and calculations are done in the browser. This means the backend is pretty tiny. That said it is running on an old box in my closet, so queries may take a while if it gets hammered.

I built it since I have worked with quite a few astronomers over the past 4 years and I keep watching them do the same steps, purely built to make my friends lives easier. I wrote it all in rust and managed to compile it into wasm. With some help from fable as I am not a frontend guy at all, I built it into a small website.

Some of the code is public, the orbital mechanics code I wrote while I worked at Caltech. Which is being used on SphereX, NEO Surveyor, and the Roman telescopes to identify known asteroids. https://github.com/dahlend/kete

Comment · 2 months ago

The writing style has significantly improved, however the token burn rate for tasks I have been working on seems to have skyrocketed. It definitely appears more capable (though I am unclear how much of that is just me liking the English it writes now vs actually more performant). I was using Fable 5 for some mathematical analysis assistance and redoing a part of it with 5.1 burned 60% of my session at a much faster rate.

Comment · 3 months ago

Strictly from an energy conservation argument this doesnt make a whole lot of sense to me. Just some back of the envelope math if they take their current mirror size, make 50k of them and overlap all of the output on the same 3 mile spot (the spot size they claim they will get on a single mirror). With an ideal reflector it is still less than mid-day daylight. Thats 50k satellites to give you direct sun over one 3 mile spot.

I suppose to make this feasible they would have to up the size of the mirrors. Unless this is somehow dirt cheap I can't imagine farmers or solar operators buying this.

Comment · 4 months ago

You can put in a public comment on these changes here:

https://www.federalregister.gov/documents/2026/05/29/2026-10...

Comment · 4 months ago

I am a researcher studying orbital dynamics of asteroids/comets/dust. I made a very precise visualization tool for the solar system, it shows the motion of all of the known asteroids. When you click on a specific asteroid it will then show the hyper precise orbit for it which matches JPL's orbit calculations (full physics, n-body, relativity, non-spherical planets).

Not mobile friendly

https://dahlend.github.io/ketev/

Comment · 5 months ago

Research grade orbital mechanics, specifically of asteroids/comets. I've been working on it for 4 years now, finally tried using some AI tooling the last few months and ended up vibe coding a fun little visualization.

(Desktop Strongly recommended) https://dahlend.github.io/ketev/

Comment · 1 year ago

I suggest the appendix of the arxiv paper if you want to see some of the math required for solar system objects beyond simple Newtonian gravity (like Relativity corrections). I wrote that section specifically because I found it a pain in the ass to source those equations in literature.

Comment · 1 year ago

Its an implementation of a pretty standard integrator used by astronomers informally called "RADAU", but it is not exactly the same RADAU you would find elsewhere. Basically it is about as good as you can typically get for multi-step integrators, tuned for speed not precision though.

Note that how the code is laid out you cant really simulate non-solar system masses. Its really aimed at massless objects in the solar system, your 3-body simulations are actually quite difficult to do given the design.

Comment · 1 year ago

Working on orbital dynamics code for my PhD in astronomy, written in rust, it can accurately calculate the positions of all asteroids/comets to within a few meters. Today I am adding a new numerical integration method which should enable me to predict orbits from observations.

https://github.com/dahlend/kete

I'm working on modeling the motion of observed dust particles coming off of comet 67P, here is are some example 3d plots:

Example of rocks ejected from one position and their possible motions: https://dahlend.github.io/67p_beta_dust.html

Trying to determine possible orbits from a set of observations (the straight lines): https://dahlend.github.io/67p_dust_orbit.html

Shout out to pyvista for making these great 3d plots possible, a little less ergonomic than matplotlib, but it can export directly to html.