For the analysis and exploration of alien planets and distant stars, often multiple measurements are evaluated based on the combination between timing and precise attitude determination. Often, images from one or more satellites are merged to achieve higher resolutions. In principle, such methods are also used for Earth observation, but here the source of the photons is closer and is disturbed by fewer factors. An important application for position determination on earth are GPS systems. These achieve their precision by selectively combining the locations of several satellites.
Mission critical is the location determination for data transmission and navigation. The speed of satellites is usually given in kilometers per second. Accordingly, even small deviations from the predicted location are sufficient for data not to be transmitted or for a collision risk to arise.
In the long term, the removal and prevention of defective satellites in orbit will also become an increasingly important issue. One approach is for satellites to observe other satellites instead of Earth or distant planets in order to demission objects with defects well before they become critical. In addition, methods are currently being tested to precisely approach a defective satellite and lower it into the atmosphere. In this way, space will remain usable for mankind in the long term.