A ground-based pulsed laser illuminates a tumbling fragment for a short window each time it passes overhead. Each pulse vaporizes a thin layer of the surface; the recoiling ablation plume pushes back on the fragment exactly like a tiny rocket exhaust — this is laser ablation propulsion, the mechanism behind proposals such as the "laser broom" and ground-based debris nudging.
Impulse per pass: Δp = Cm · P · t_dwell
Δv per pass: Δv = Δp / m (applied retrograde)
Vis-viva: v² = μ(2/r − 1/a)
New semi-major axis: a' = −μ / (2·[(v−Δv)²/2 − μ/r])
The beam is aimed opposite the fragment's velocity at the top of its orbit (apogee), so each pass acts like a tiny retrograde rocket burn there. Because the burn point stays the highest point of the orbit, the apogee altitude barely moves while the opposite side of the ellipse — perigee — keeps dropping. Once perigee sinks to roughly 120 km, atmospheric drag takes over within a few more passes and the fragment re-enters and burns up.
- Laser power and Cm (the momentum coupling coefficient, a material/fluence property, typically tens of µN per watt for ablation propulsion) set the thrust force F = Cm·P.
- Dwell time is how long the tracking system can keep the beam locked on target during one overhead pass.
- Debris mass sets how much that impulse actually changes the fragment's velocity — heavier junk needs far more passes.
- Time warp only speeds up the visualization clock — it does not change the physics, so the pass count and altitude curve are identical at any warp setting.
Real systems (e.g. proposed EOS/DLR ground-laser concepts) use exactly this coupling: kilowatt-class pulsed lasers, ablation impulse coupling of tens of µN/W, and dozens to thousands of passes to deorbit a single small fragment — which is why laser ablation is discussed mainly for centimeter-to-decimeter debris rather than intact satellites.
This 2D build renders the same orbital plane the 3D version uses, seen face-on rather than tilted — the orbital mechanics (vis-viva, apsis geometry) are identical; drag to pan the view and scroll/pinch to zoom.