Re: iridium operational spares?

Ed Cannon (ecannon@mail.utexas.edu)
Mon, 09 Mar 1998 02:55:56 -0600

Here's the launch schedule for the remaining Iridiums, 
gleaned from Florida Today's extended launch schedule  
(http://www.flatoday.com/space/next/sked.htm):

  March 18:  Long March --  2 sats
  March 23:  Delta 2 --     5 sats
  April ??:  Proton --      7 sats
  April 18:  Delta 2 --     5 sats
  April ??:  Long March --  2 sats
  May 29:    Delta 2 --     5 sats
  June ??:   Delta 2 --     5 sats
                           --
                           31

Those plus the 51 already up there yields 82 -- which 
seems like too many!  But subtracting six spares and 
two or three (?) that are known to be non-usable leaves 
73 or 74.  (Maybe one or two more are questionable?)
What's the plan for in a number of years, as those of 
the those in the first operational generation go out of
service?

Aside on "glint" and "flare":  To me the word "glint" 
implies faint, brief, and sudden, so I find it difficult 
to think of that applying accurately to what Iridiums 
are observed to do.  The HST maxima I've seen are briefer 
than those of Iridiums, but they're very bright (at least 
-2 and sometimes much brighter).  In a way they are more 
like what Rob McNaught said about meteor flares -- "a 
short-lived increase in intensity superimposed on the 
overall intensity profile".  The main meaning of "flare" 
that I feel applies very well to the Iridium phenomenon 
is the *gradual* brightening and dimming.  One point in 
favor of "glint" is that it implies only reflected light, 
which "flare" and "flash" do not.  Thanks to Jeff Hunt
for looking up Sue Worden's post last year; I like it
very much also:

http://www.satellite.eu.org/seesat/Oct-1997/0329.html

Ed Cannon
ecannon@mail.utexas.edu
Austin, Texas, USA