Subject: [IGSMAIL-0570] Block-1 est morte!
From: Tom Clark
Date: Mon, 18 Apr 1994 10:47:47 PDT

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IGS Electronic Mail      Mon Apr 18 10:47:47 PDT 1994      Message Number 0570
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Author: Tom Clark
Subject: Block-1 est morte!

I don't know how many of you had noticed, but over the past ~ 10 days, the 
DoD has deactivated all but one of the Block-1 satellites. Both PRN-3 and 
PRN-13 have been showing unhealthy and transmitting bogus ephemerides. A few
minutes ago (06:00 UTC, 16 April) I checked and it appeared that PRN-3
(then at ~ 70 degrees elevation) was transmitting, but very weak. I have
not verified if PRN-13 has been transmitting in the past few days but it
was last weekend.

By my listings, this leaves PRN-12 as the only Block-1 satellite still 
active. This unannounced event apparently happened about 10 days ago,
after the latest Block-2 satellite (PRN-6) was activated, which gave the 
DoD a full operational constellation of 24 Block 2 satellites (PRN's
1,2,4,5,6,7,9,14 thru 29 and 31).

I was chatting with a knowledgeable DoD person late Friday and he confirmed 
my observation. He indicated that the Block-1 satellites were too labor 
intensive (i.e. expensive) to maintain and the DoD did not choose to keep 
the tired old satellites operating with their reduced budgets. According
to him, any signals heard simply reflect end-of-life testing.

The last three Block-1 satellites are shown in the standard table, which
I have updated as follows:
 
                     NASA   Orbit   Launch
    PRN  Internat. Catalog  Plane    Date
SVN Code    ID      Number  Pos'n    (UT)   Clock  Available/Decommissioned
---------------------------------------------------------------------------
 09  13  1984-059A  15039    C-1   84-06-13   Rb   84-07-19 thru 94-04-??
 10  12  1984-097A  15271    A-1   84-09-08   Rb   84-10-03
 11  03  1985-093A  16129    C-4   85-10-09   Rb   85-10-30 thru 94-04-??

This is a sad happening for those of us who liked having a few non-SA
satellites for clock synchronization. I saw no announcement of the Block-1
decommissioning -- did anyone?

Tom Clark