Dock a rescue avionics package at a damaged station module
You are the guidance officer aboard a chaser craft in Low Earth Orbit. Your crew vehicle and the station are both falling around Earth — you feel weightless, but gravity is still 90% of surface value. Docking is not about "flying to the target." It's about matching relative velocity within a narrow approach corridor.
"There's no gravity in orbit, so I can just aim at the station and thrust."
Wrong! In orbit, objects in the same direction but at different altitudes move at different speeds (v = √(GM/r)). A direct chase curves away in the rotating frame. The physics punishes impatience.
Orbital velocity: v = √(GM/r) · Centripetal force: F = mv²/r · Period: T = 2π√(r³/GM) · The key insight: lower orbit = faster speed. Speeding up raises your orbit and slows you relative to the station.
35% dock success · 30% science quality (correct burns) · 20% fuel efficiency · 15% safe closure rate
Stars: ★★★ = velocity matched + corridor kept + fuel reserve
A/← retrograde · D/→ prograde · W/↑ radial-in · S/↓ radial-out
H = hint (-5pts) · P = pause (quiz!) · F = fast ×6 · M = sound · R = restart
English-only official build • upper-secondary orbital docking • physically grounded relative motion
Wide approach lane, generous fuel, mild drift. Best first run for learning why calm docking beats aggressive chasing.
Tighter corridor, stronger drift, less fuel. Rewards early correction and better velocity discipline.
Narrow envelope, thin fuel margin, larger initial offset. Late panic burns punish fast.
“There is no gravity in orbit, so I can fly straight at the station.”
Dock a rescue avionics package at Port A before the station loses guidance redundancy. You are the guidance officer aboard the chaser craft.
Safe dock: range ≤ 8 m, relative speed ≤ 0.35 m/s, stay inside the approach corridor.
Controls: A/← retrograde, D/→ prograde, W/↑ radial-in, S/↓ radial-out, F fast-forward ×6, M sound, H hints, P pause, R restart. Tap any thruster to start instantly.
Tip: in orbit, being near the station is not enough. You must also remove relative speed.
Both spacecraft orbit Earth under gravity (F = GMm/r²). They feel weightless because they're in free fall — not because gravity is absent. At 400 km altitude, g ≈ 8.7 m/s² (89% of surface value). Docking = relative-motion problem in the co-orbiting LVLH reference frame.
Use small, early burns. Kill cross-track drift and relative speed before the final meters.
Pre-launch
The chaser is parked in the approach lane. Read the corridor before you commit to thrust.
Astronauts feel weightless in orbit because spacecraft and crew are in free fall — not because gravity has vanished. Safe docking needs position control and velocity matching.
Press P to pause and get a physics challenge! Correct answers earn +3 bonus points.
ISA Flight: Station in sight. Guidance is yours. Bring the package in clean.
No run yet.
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