Interplanetary navigation is the determination of the position and continuous tracking of interplanetary space probes and their direction and attitude control. All four tasks are the prerequisite for the precise control of trajectories in the solar system and also in its outer space.
Velocity and location are determined by special observation stations on Earth, and in some cases also on Earth satellites. The orbit of the probes can be determined – depending on the mission target – in two coordinate systems:
- geocentric (with respect to the earth, especially in the case of lunar flights), or
- barycentric (with respect to the center of gravity of the solar system), to which still
- the topocentric system of the spacecraft. The latter is important for various methods of on-board autonomous navigation of the spacecraft.
In contrast to the two- or three-dimensional navigation in nautics and aviation, time is decisive as the fourth dimension in space travel because the targets to be reached are also in rapid motion. In addition, the propulsion of the missiles is only active for a short time, which means that even the smallest errors lead to large orbital deviations.
Locating methods from the earth
- Directional measurement with very fast telescopes
- Distance measurement (limited range) by means of laser
- with radio waves:
- Direction measurement with large radio telescopes, e.g. of the Deep Space Network. With the Delta DOR method, a very high accuracy can be achieved.
- Interferometry analogous to the VLBI method
- Distance measurement according to the radar principle
- Speed by means of Doppler effect and
- Distance differences from its integration (analogous to hyperbolic navigation).
On-board autonomous methods
- Spatial orientation by sun and star sensors, especially for attitude control
- Infrared homing (control of celestial bodies with infrared sensor)
- Gyro stabilization and inertial navigation (acceleration measurement)
- Direction measurement to planets, especially during flybys (e.g. Cassini-Huygens)
- Satellite-to-Satellite Tracking (only near earth)
- Analysis of gravity gradients and magnetic fields
- Comparison of the arrival times of pulsar signals
- Transition orbits, flyby (spaceflight)
- astronomical navigation
- Stabilization (aerospace), control nozzle
- Richard Gliese: Weltraumforschung Band I (p.181, 191ff), Bibl.Inst. Heidelberg 1966
- Udo Renner et al: Satellitentechnik — eine Einführung. Springer-Verlag Berlin-Heidelberg 1988
- Ernst Messerschmid, Stefanos Fasoulas: Space Systems. An introduction with exercises and solutions. Springer, Berlin 2005, ISBN 3-540-21037-7