Space Elevator Simulator

A physics-based 3D simulation of space elevator, built in VPython. The climber ascends from 100 km altitude to geostationary orbit and beyond, driven by real orbital mechanics - not canned animations.

What it simulates

• Climber dynamics - ODE-integrated trajectory with a PD velocity controller targeting 55.6 m/s (~200 km/h). Effective gravity transitions from downward (below GEO) through zero (at GEO) to outward (above GEO).
• Coriolis tether waves - Finite-difference wave propagation along the tether, driven by the Coriolis force the climbing mass exerts. Tapered mass density and tension from the CNT cross-section profile.
• Tether tapering - Cross-section follows the exponential taper ratio for a carbon nanotube ribbon under constant stress, thickest at GEO altitude.
• Proper scale mapping - A power-law visual compression (alt^0.45) keeps near-surface detail visible while still showing GEO and the 100,000 km counterweight.

3D Visualization

The main visualization (space_elevator_3d.py) shows:

• Textured spinning Earth with 23.44° axial tilt and atmosphere glow
• Tapered tether with physically-computed Coriolis wave deflections
• Climber box with trail, tracking the ODE solution
• GEO marker ring at 35,786 km
• Counterweight at 100,000 km
• Live HUD: altitude, velocity, effective-g, elapsed time, force-balance phase
• Time warp slider (10 min to 10 hours per visual second)
• Pause/resume control

Project structure

• constants.py - Physical constants, GEO radius, effective gravity, taper ratio.
• climber_dynamics.py - Standalone climber ODE solver and plots.
• taper_analysis.py - Tether taper profile and summary metrics.
• tether_waves.py - Finite-difference tether wave simulation.
• simulation_ui.py - Integrated UI to run and compare all three model views.
• UI_SPEC.md - UI architecture and implementation specification.

Run

Install dependencies:

pip install -r requirements.txt

Launch integrated UI:

python simulation_ui.py

Launch standalone scripts:

python climber_dynamics.py
python taper_analysis.py
python tether_waves.py

Integrated UI Modes

• Climber:
  • Interactive run/pause/step/reset.
  • Live altitude/time and velocity/altitude plots.
  • Transparency panel with equations and runtime values.
• Taper:
  • Uses taper_analysis.analyze_taper(...).
  • Shows area ratio and normalized linear density profiles.
  • Displays key taper metrics (GEO/peak/top ratios).
• Waves:
  • Uses tether_waves.simulate_tether_waves(...).
  • Shows final tether deflection and amplitude-over-time.
  • Displays stability diagnostics (CFL estimate).