Fighting perturbations
A spacecraft in orbit is continuously nudged by:
- Earth oblateness (J2, J3, J4)
- Luni-solar gravity
- Solar radiation pressure
- Atmospheric drag (LEO)
- Third-body perturbations
Station-keeping is the regular use of small burns to stay within a tolerance box around the nominal orbit.
Typical budgets
- GEO east-west: ~2 m/s/year
- GEO north-south (inclination): ~50 m/s/year (dominant cost)
- LEO drag makeup at ~400 km: ~5 to 20 m/s/year depending on solar activity
Orbital period calculator
Use the third-law calculator below to compute the orbital period of a circular orbit at arbitrary altitude. This directly drives how often you need to revisit a control point.