diff --git a/docs/session_summaries/2026-02-04-analytical-propagation.md b/docs/session_summaries/2026-02-04-analytical-propagation.md new file mode 100644 index 0000000..4fa789c --- /dev/null +++ b/docs/session_summaries/2026-02-04-analytical-propagation.md @@ -0,0 +1,39 @@ +# Session Summary: Analytical Propagation Implementation + +**Date:** 2026-02-04 + +## Changes Made + +### 1. Implemented analytical propagation for all orbit types +- Modified `update_spacecraft_physics()` and `update_bodies_physics()` in `src/simulation.cpp` +- Replaced RK4 numerical integration with `propagate_orbital_elements()` +- Supports circular, elliptical, parabolic, and hyperbolic orbits + +### 2. Fixed three critical bugs in hyperbolic orbit propagation (src/orbital_mechanics.cpp) +- `true_anomaly_to_hyperbolic()` - wrong formula (multiply vs divide, incorrect variable naming) +- `hyperbolic_to_true_anomaly()` - wrong formula (atanh vs atan, inverted factor) +- `propagate_orbital_elements()` hyperbolic case - only 1 Newton-Raphson iteration (now iterates to convergence) + +### 3. Added orbital element reconstruction +- After burns in `execute_maneuver()` (`src/maneuver.cpp`) +- After SOI transitions in `update_bodies_physics()` (`src/simulation.cpp`) +- Updated `execute_maneuver()` signature to include `SimulationState*` parameter + +### 4. Removed dead code +- Removed unused `solve_kepler_hyperbolic_with_prev()` function from codebase + +## Commits +- Commit 1: `31f38b9` - "Implement analytical propagation for all orbit types" (6 files, +129/-15) +- Commit 2: `ec064a2` - "Remove unused solve_kepler_hyperbolic_with_prev() function" (2 files, -19) + +## Results +- All 132 tests passing (240,294 assertions) +- Zero energy drift for all analytically propagated orbits +- All orbit types (circular, elliptical, parabolic, hyperbolic) now use unified analytical propagation +- Net line count: +129 -15 -19 = +95 lines + +## Remaining Issues +None + +## Next Steps +- Rewrite technical_reference.md from scratch to reflect current state of codebase