Task 050: Saturn-Centric Enceladus Capture Diagram for EP02

Status: DONE

Motivation

Every planet system encounter in the series has a local-scale orbital diagram except Saturn:

• EP02: Jupiter-centric escape diagram ✓
• EP03: Uranus-centric Titania approach ✓
• EP04: Uranus-centric Titania departure ✓
• EP05: Earth-centric capture diagram ✓
• EP02: Saturn-centric Enceladus capture — MISSING → now DONE

The Enceladus capture is only shown in the heliocentric EP02 diagram, where Saturn's moons are invisible at that scale. Adding a Saturn-centric diagram shows the moon orbits and capture trajectory, completing the planet-system coverage.

Results

• Added ep02-diagram-03: "土星中心座標: エンケラドス捕獲"
• Saturn-centric, sqrt scale, radiusUnit=km
• Shows: Saturn rings (D環 inner, F環 outer), Mimas, Enceladus (target), Tethys, Dione, Rhea, Titan
• Approach from 30 RS (1,808,040 km) with hyperbolic capture to Enceladus orbit
• Animated (200,000s duration) with capture burn marker (ΔV≥0.61 km/s)
• All moon mean motions included for orbital animation
• Codex review: confirmed sqrt scale, rings as visual reference, 30 RS approach
• Tests: 877 TS + 86 Rust = 963 total (0 failures)
• Build: successful, diagram renders correctly in ep-002.html

Scope

1. Add a Saturn-centric orbital diagram (ep02-diagram-03) to ep02.json

- Show major Saturn moons (Mimas, Enceladus, Tethys, Dione, Rhea, Titan)

- Show Saturn rings (D環, F環) as subtle visual references

- Show Enceladus capture trajectory (hyperbolic approach)

- Animate the capture sequence with moon orbital motion

- Add burn marker for capture ΔV (≥ 0.61 km/s from EP02 analysis)

1. Existing generic validation tests automatically cover new diagram
2. Build and verify report rendering — confirmed

Depends on

• Task 008 (EP02 analysis) — DONE
• Task 014 (orbital diagram types) — DONE
• Task 040 (engine burn visualization) — DONE