Iridium Flare End-Of-Life

For twenty years Iridium Communications Inc has provided global communications with a fleet of 66 satellites, plus spares. For most of that time the satellites have had the same design, and a consequence of that design was their ability to produce very bright and predictable flares due to the reflection of the Sun off their Main Mission Antennae. Beginning January 14 2017, though, satellites of the original design are being replaced by a new design that does not flare nearly as often or as brightly.

Perl module Astro::Coord::ECI::TLE::Iridium, part of the Astro-satpass distribution, predicts these flares. It seems to me to be time to start thinking about how to retire this module.

At this point in time, I see the retirement process to consist simply of removing this module to its own distribution. I do not plan to delete it from CPAN, since it may be of historical interest. Astro::Coord::ECI::TLE will continue to recognize Iridium satellites, but ignore their special properties (probably with a warning) if Astro::Coord::ECI::TLE::Iridium can not be loaded. If I have not already done so, I may take this opportunity to rename the distribution to Astro-Coord-ECI, which it should have been all along.

As a first step, I am adding back to the canned Iridium status table in Astro::Coord::ECI::TLE all the Iridium satellites whose orbits have decayed. Obviously can_flare() returns false for these, but if you pass argument 'all' to it, it will return true regardless of the status of the Iridium satelite. If I can find out when each satellite stopped generating predictable flares I will add that information as well, but at this point I do not hold much hope of that.

As for the timing, I intend to make the move once all of the originial-design Iridium satellites are out of service. The trick here is that Iridium Communications does not provide information on the status of their fleet. I know of two sources: Dr T. S. Kelso's Celestrak web site, and Rod Sladen's Iridium Constellation Status. I am generally guided by the former, since I believe Dr. Kelso calls Iridium from time to time for updates, whereas I am ignorant of where Mr. Sladen gets his information.

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About Tom Wyant

user-pic Fine Perl code for over 0.005 centuries.