Visual
SAT-Flare Tracker 3D
1.0 MODELLING OF FAST ROTATING SATELLITES
This
section shows how to model a fast rotating satellite in order to
compute its rotation axis and to track its reflective surfaces. By
assuming
that the satellite's rotation axis is not changing considerably within
the period of interest, the rotation can be easily modelled if at least
three bright flashes have been observed from the same reflective
surface
under quite different satellite positions. However, since the satellite
may have more than one highly reflective surface, the biggest difficult
is to discriminate the surface that generates the flashes and to make
sure the employed flashes are actually generated by the same
surface.
After a series of flashes have been collected, the modelling is started by setting the None orientation in the Satellite Orientation frame of the Satellite Surface Modelling
window. This allows each observed flash to be entered as if it was
generated by an independent surface of a non-rotating satellite. To
obtain this:
- set the program time to the observed flash moment
- add the surface by clicking on the Add Mirror button of the Satellite Surface Modelling window
- orient the new surface by clicking on the Auto Orient Mirror To Flare button of the Satellite Surface Modelling window
- repeat the previous three steps for all the gathered flashes.
At
this point, three flashes that are believed to be related to the same
surface have to be selected and moved at the top of the surface list.
To move a surface at the top of the list, select its entry and click on
the UP button of the Satellite Surface Modelling window.
When the first three surfaces are correctly moved at the top of the list, change the satellite orientation to Rotating in the Satellite Orientation frame of the Satellite Surface Modelling window. Now it is possible to compute the satellite's rotation axis by clicking on the Compute Rotation Axis button of the Satellite Surface Modelling window.
If the previous steps have been correctly performed, the flashes projected on the ground by the rotation of the first surface in the list (all the other surfaces are ignored) will be displayed (make sure the Show Satellite Flares/Shadows option in the Tracking menu bar item is active).
If the flashes of a different rotating surface are desired, just move the surface entry at the top of the list by mean of the UP button of the Satellite Surface Modelling window.
To publish the model, or just to send the results to another observer, please export the model by means of the Export Model button at the right side of the Satellite Surface Modelling window, and then copy and past the printed text.
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By
Simone Corbellini
