Hi Gerhard, > The only information I found about the Iridium solar panels is that > they can be rotated about one direction (up to now I had assumed > that they are either fixed or that they point straight toward the > sun - this seems to be wrong). I would assume that the solar panels > can be rotated about the direction of flight. Is this correct? > Does anybody have some more accurate information about the alignment > and movements of the Iridium solar arrays (or where to find this > information)? Iridium solar panel pointing rules are complicated. Most of the time they track the sun, but there are seasons when this is not possible due to gimbal limits. As I recall (from having coded this in iridflar), there are three separate pointing modes depending on the solar beta angle. Most of the time each Iridium has no problem tracking the sun throughout its orbit (mode 1), and of course solar panel flares are not possible at these times. I believe the cutoff for mode 1 is beta angles of 40 degrees or less. From beta 40 to (I think) 65, you go to mode 2 in which the gimbal azimuth is locked at +/- 40 degrees, but the elevation gimbal still swings 0-360 degrees to maximum the solar incidence angle. In mode 3 (solar beta > 65), the arrays are simply locked pointing left or right (depending on which hemisphere the sun is in). Solar array flares are possible in modes 2 and 3. Since beta angles are constant for a given orbital plane, if one satellite produces solar array flares on a particular date, all satellites in its plane will also. --Rob ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Wed May 18 2005 - 17:25:47 EDT