Referansebane

Referansebane is a concept used in space mission design and operations to denote a nominal, mathematically defined orbital path against which the spacecraft’s actual trajectory is measured. The referansebane serves as the baseline orbit chosen during mission design to satisfy mission requirements and to provide a reference for navigation, trajectory planning, and performance assessment. It is specified by standard orbital elements—the semi-major axis (a), eccentricity (e), inclination (i), longitude of the ascending node (Ω), argument of periapsis (ω), and the true anomaly or epoch—describing the orbit at a given reference time.

In operations, the referansebane provides the target for maneuvers and the yardstick for deviation: the current state of the spacecraft (position and velocity) is compared to the referansebane, and required delta-v is computed to keep deviations within predefined tolerances. Perturbations such as atmospheric drag, gravitational harmonics, third-body effects, and solar radiation pressure cause drift away from the referansebane, requiring occasional corrections. The referansebane may be updated if mission plans change or after planned propulsion maneuvers.

The referansebane is distinct from the actual operational orbit, which is the real, evolving trajectory. It can be shared across a fleet (as in a satellite constellation) to ensure cohesive trajectories and predictable conjunction management. For example, a low Earth orbit mission might use a circular referansebane at approximately 550 km altitude with a near-polar inclination as the nominal baseline.