Field Notes
Working notes on the systems, simulations, and open-source tools I build: how they are architected, what the real constraints were, and what held up under use.
Build logs, architecture write-ups, and open-source releases for engineers and technical leaders who care about how things are actually made, not just theorized.
Arbor Engineering Group publishes Field Notes to share the engineering behind the ideas: the open-source projects, systems built in the open, and the design decisions that shaped them.
Focus: Open-source releases, systems design, simulation, applied engineering
Purpose: Show how real systems are built and what the constraints demanded
How Do You Validate a Trajectory Propagator?
A propagator can be correct to 0.01% on one metric and 20 km wrong on another, in the same run, with both numbers honest. The validation record for cislunar-sim against LightSail 2 — including the result I called strongest, and why I was wrong about it.
Architecture Field Note: cislunar-sim
cislunar-sim, the physics and guidance core of a larger in-house spacecraft simulation engine, is now open source, reviewed here the way it would have been reviewed internally: down to the bug a re-validation run turned up and the headline claim a later review had to withdraw.
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