diff --git a/docs/future_work.md b/docs/future_work.md index 8be3d3e..08683d1 100644 --- a/docs/future_work.md +++ b/docs/future_work.md @@ -26,32 +26,38 @@ This document outlines planned enhancements and future development areas for the - Add validation tests for energy/momentum conservation - Consider relative velocity of parent bodies -### More Accurate Integration Methods -**Current:** RK4 (Runge-Kutta 4th order) integration -**Proposed:** Newton-Raphson propagation for higher precision +### Newton-Raphson Analytical Propagation +**Current:** RK4 (Runge-Kutta 4th order) numerical integration +**Proposed:** Newton-Raphson analytical propagation with hybrid burn handling + +**Status:** Implementation plan created - see `docs/newton_raphson_propagation_plan.md` **Benefits:** -- Improved accuracy for long-term orbit predictions -- Better handling of near-parabolic trajectories - -**Implementation Considerations:** -- May require adaptive timestep sizing -- More complex than RK4 -- Trade-off between accuracy and performance - -### Io and Titan Orbital Stability Tuning -**Issue:** Outer solar system moons exhibit orbital drift - -**Approaches:** -- Reduced timestep for moon systems -- Specialized local frame handling -- Higher precision for distant parent-body interactions -- Moon-specific integration parameters - -**Validation:** -- Long-term stability tests (> 100 orbits) -- Energy conservation metrics -- Orbital period accuracy verification +- Time steps of hours/days (vs. seconds/minutes with RK4) +- 60-2880x performance improvement depending on orbit scale +- Perfect 2-body accuracy with no numerical drift +- Newton-Raphson converges in 3-5 iterations + +**Implementation Approach:** +- Analytical propagation for orbital motion (99% of simulation time) +- RK4 integration during finite-duration burns (1% of time) +- Seamless transitions between modes +- SOI transitions with orbital element transformations + +**Estimated Effort:** 30-44 hours across 5 implementation phases + +### Orbital Stability Validation +**Status:** Time step stability analysis complete + +**Findings (from `tests/informational/test_time_step_stability`):** +- RK4 at 60s is very stable (22% of stability limit) +- Mercury orbiter (MESSENGER-like) is limiting factor: 270s max stable dt +- Io and Moon are very stable (>596s max stable dt) +- Current default (60s) provides excellent margin + +**Documentation:** See `tests/informational/README.md` for test details and results + +**Conclusion:** No stability tuning needed - RK4 works well for moon systems with existing dt=60s default ## Visualization Enhancements