Ground Track Calculator

Compute subsatellite position from practical orbital parameters. Review period, longitude shift, coverage span, and speed. Use structured results for missions, analysis, testing, and planning.

Enter Orbital Inputs

Example Data Table

Altitude (km) Inclination (°) RAAN (°) Argument of Perigee (°) True Anomaly (°) Time Step (s) Points
500 51.6 25 10 0 300 24
700 98.2 15 5 20 240 30
35786 0.1 75 0 180 600 18

Formula Used

The calculator models a simplified orbital ground track using classical orbital relationships. First, semi major axis is estimated as a = RE + h. Mean motion is then n = √(μ / a³). Orbital period is T = 2π / n.

The instantaneous subsatellite point comes from the orbit frame projected into Earth fixed coordinates. Using inclination i, right ascension of ascending node Ω, argument of perigee ω, and true anomaly ν, the argument of latitude becomes u = ω + ν.

Position components in the inertial frame are rotated by Earth rotation angle θ = ωE t. Latitude is obtained from φ = atan2(z, √(x²+y²)) and longitude from λ = atan2(y, x). Longitude shift per orbit is approximated from the ratio of orbital period to sidereal day.

This engineering calculator is ideal for quick planning, screening, and educational analysis. It does not replace high precision perturbation models, drag models, or full propagator software.

How to Use This Calculator

  1. Enter the spacecraft altitude above Earth surface in kilometers.
  2. Provide orbital geometry values, including inclination, RAAN, argument of perigee, and true anomaly.
  3. Set time step and the number of points for the generated ground track.
  4. Keep the Earth constants or replace them with project specific values.
  5. Press Calculate Ground Track to display results below the header and above the form.
  6. Review summary metrics, inspect the plotted path, and study the generated coordinate table.
  7. Use the CSV or PDF buttons to export the calculated results.

Frequently Asked Questions

1. What does a ground track show?

A ground track shows the subsatellite path across Earth’s surface as the spacecraft moves in orbit and Earth rotates beneath it.

2. Why does the path shift westward or eastward?

The track shifts because Earth rotates during each orbit. The amount of shift depends mainly on orbital period and Earth’s sidereal rotation rate.

3. Is this calculator useful for low Earth orbit missions?

Yes. It is especially useful for quick low Earth orbit planning, visibility studies, coverage checks, and conceptual mission screening.

4. Does the calculator handle eccentric orbits exactly?

It accepts eccentricity, but the propagation is simplified for engineering speed. For high fidelity eccentric orbit studies, use a full orbital propagator.

5. What is the meaning of repeat orbits?

Repeat orbits estimate how many revolutions are needed before the ground track roughly aligns again with earlier longitudes.

6. Why is maximum latitude related to inclination?

For most cases, the highest absolute latitude reached by the subsatellite point is close to the orbital inclination, assuming a prograde or retrograde orbit.

7. Can I export the computed coordinates?

Yes. The page includes CSV export for table data and PDF export for a printable summary of the calculated output section.

8. Is this suitable for final mission certification?

No. It is best for preliminary engineering analysis. Certified mission work should use validated dynamics tools and perturbation aware propagation methods.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.