Sun-Synchronous Orbit Calculator
Compute the inclination required for a sun-synchronous orbit from altitude. Includes nodal regression rate, mean local time, and eccentricity effects.
What It Does
The Sun-Synchronous Orbit Calculator returns the inclination required to make a circular orbit's nodal regression rate match Earth's mean orbital rate (about 0.9856°/day), giving the spacecraft a constant local solar time at the equator crossing. Input altitude (or semi-major axis) and the calculator returns the SSO inclination, the J2-driven nodal regression rate, and the orbit period. Supports the slightly elliptical case (frozen orbits) with a separate eccentricity field.
Key Features
- Required SSO inclination from altitude using J2 nodal regression
- Support for elliptical (frozen) sun-synchronous orbits
- Output of nodal regression rate, period, and ground-track repeat
- Mean local solar time at descending node selection
Why It Matters
Sun-synchronous orbits are the workhorse of Earth observation — every Landsat, Sentinel, and most commercial imaging constellations fly SSO so the lighting angle at every ground target stays consistent across passes. The required inclination is non-obvious: a 600 km SSO needs about 97.79°, not the 98° you might guess. Off by a tenth of a degree and your dawn-dusk orbit drifts into noon-midnight in months, which kills your solar power budget. The calculator nails the inclination at the altitude you actually want.
Start a free pilot to use this calculator with your own mission parameters.
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All 50+ engineering calculators are available on every SMAD Portal plan, starting at $29/month. No add-ons, no per-calculator fees.