Tool 19 · Space Environment & Drag

Orbital Decay Simulator

Simulate altitude loss over time using ballistic coefficient, atmospheric density, and drag acceleration. This tool connects directly to the Ballistic Coefficient Calculator, Atmospheric Density Tool, and ML-based orbital decay work.

What this tool computes

Orbital decay is driven by atmospheric drag. The lower the altitude and the lower the ballistic coefficient, the faster a satellite or debris object loses orbital energy and altitude.

  • Altitude history over time
  • Atmospheric density along the orbit
  • Approximate drag acceleration
  • Orbit period change
  • Estimated time to a selected decay threshold
  • Comparison between low, moderate, and high solar activity

Ballistic coefficient connection

This simulator uses the same ballistic coefficient concept from your BC calculator:

\[ \beta = \frac{m}{C_D A} \]

Smaller \(\beta\) means a larger drag acceleration for the same density and orbital speed.

Drag acceleration model

Drag acceleration is estimated from density, orbital speed, and ballistic coefficient:

\[ a_D \approx \frac{1}{2}\rho v^2\frac{1}{\beta} \]

The tool uses a simplified energy-based decay approximation to translate drag acceleration into semi-major-axis loss.

Why this matters for your thesis

Your thesis work estimates ballistic coefficient from TLE and atmospheric data. This tool gives readers a visual way to see why BC, density, and solar activity matter for orbit prediction.

  • At 700 km, decay may be slow.
  • At 400 km, solar activity becomes important.
  • Below 250 km, decay accelerates rapidly.
  • BC uncertainty can strongly change lifetime estimates.

Educational warning

This is an educational decay model. It is not a replacement for SGP4, numerical orbit propagation, NRLMSISE-00, or re-entry prediction software.

Interactive orbital decay simulator

Presets adjust altitude, BC, and space-weather conditions.

Results

Effective ballistic coefficient

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Initial density

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Initial drag acceleration

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Final altitude

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Altitude loss

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Threshold crossing

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Interpretation

Run the simulator to see altitude decay over time.

Altitude decay over time
Density and drag acceleration history
Solar activity comparison

Assumptions and limitations

This simulator assumes:

  • Near-circular orbit approximation
  • Simplified density model
  • No eccentricity, J2, attitude variation, lift, or SRP
  • No actual re-entry heating or breakup physics
  • Decay rate is for learning and comparison only
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