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Space Shuttle Navigation: Difference between revisions
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The basic characteristics of the navigational problem (including error propagation, sensor quality with respect to the propagated state, state vector corrections) are modeled in FG. | The basic characteristics of the navigational problem (including error propagation, sensor quality with respect to the propagated state, state vector corrections) are modeled in FG. | ||
== | == Orbital navigation Navigation == | ||
=== The star tracker === | |||
==== Hardware ==== | |||
The star tracker system consists of two cameras, a left-pointing (-Y) and and upward pointing (-Z) system. Each of these has about a 10 deg field of view. If the star tracker observes a star within its visual field, it utilizes a list of ~100 bright stars stored in the data base to compare the coordinates in the sky using the current state vector with the coordinates the star should have from the data base. Measuring two stars that way gives an accurate update of the inertial attitude. | |||
However, stars can only be identified by their position, so if the angular difference of internal and true state vector exceeds 1.2 deg, the star tracker can no longer operate - in this case the COAS has to be used to correct attitude. | |||
Part of the orbital arrival procedure is to open the star tracker doors (which need to be closed for de-orbiting) - once that has done, the star tracker is operational. | |||
==== Usage in FG ==== | |||
In orbit, the star tracker is controlled via SPEC 22. | |||
[[File:Shuttle avionics spec22.jpg|600px|STRK/COAS display of the Space Shuttle]] | |||