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Ephemeris
Definition
Ephemeris is a dataset providing the calculated positions of celestial objects over a period of time.
These celestial objects can include planets, moons, stars, satellites, and other objects in space.
The ephemeris data is crucial for navigation and determining the precise location of these objects at specific times, making it indispensable in astronomy, space exploration, and communications.
Typically, ephemeris data is used to support activities such as satellite tracking, space mission planning, navigation systems, and related astronomical observations.
The accuracy and reliability of ephemeris data are paramount, as they enable precise calculations required for tasks such as space traffic management, satellite collision avoidance, and the alignment of telescopes for observational purposes.
In the context of space operations, ephemeris data is often updated and derived from observations and analysis, to ensure that it accurately reflects the actual orbits and positions of the tracked objects.
Why ephemerides matter for space operations and traffic management
Ephemerides are the operational “truth table” for where a spacecraft (or any tracked object) is expected to be at a given time.
They underpin:
- conjunction assessment
- mission planning
- ground-station scheduling
- sensor pointing
- coordinated operations across constellations
In Space Traffic Management, ephemeris quality directly drives the uncertainty in predicted close approaches: stale or poorly estimated ephemerides increase false alarms, missed risks, and unnecessary maneuvers, while accurate, frequently updated ephemerides enable earlier, more confident decisions, safer maneuver planning, and more scalable fleet operations.
Because orbits evolve due to maneuvers and perturbations, ephemerides must be continuously refined from observations and consistently shared across stakeholders to maintain a reliable space picture.
How Look Up improves ephemeris accuracy and timeliness
Look Up strengthens ephemeris accuracy and timeliness by:
- detecting and tracking objects in LEO with SORASYS radars (down to 10 cm, with centimetric accuracy)
- tasking measurements on-demand when operational situations require rapid updates
Through the SYNAPSE SSA digital platform, Look Up fuses its sensor data with external sources to update trajectories, catalogue objects, and deliver ephemeris-relevant products via API or interface, supporting collision avoidance workflows, maneuver detection, and low-latency alerts for high-interest events.
This combination helps operators reduce orbital uncertainty, improve conjunction assessments, and coordinate safer, more efficient operations at scale.
We deliver space situational awareness (SSA) and space domain awareness (SDA) solutions that help secure active satellites and ensure safe operations in the ever-growing expanse of space.