GPS BLOCK I SATELLITES
The satellite vehicle numbers (SVN) 1 through 11 are designated as Block I. The Block I satellites were launched from 1978 to 1985 at Vandenberg AFB, California using the Atlas E/F. Block I are referred to as the original concept validation satellites developed by Rockwell International and reflect various stages of system development.
The Block I satellites operated in circular 10,900 nm orbits, with a 12-hour period, the same as the Block II satellites. The Block I satellites are/were positioned in the same orbital planes as the Block II, but at an inclination angle of 63 degrees. Each Block I satellite contained one cesium and two rubidium atomic clocks. The
design life of the Block I satellites was 5 years, but a majority performed well beyond their life expectancy.
BLOCK I SATELLITES
LAUNCH US SPACE**
SVN PRN DATE COMMAND
-------------------------------------
*01 04 22 FEB 78 10684
*02 07 13 MAY 78 10893
*03 06 06 OCT 78 11054
*04 08 10 DEC 78 11141
*05 05 09 FEB 80 11690
*06 09 26 APR 80 11783
*07 NONE
*08 11 14 JUL 83 14189
*09 13 13 JUN 84 15039
*10 12 08 SEP 84 15271
*11 03 09 OCT 85 16129
* Satellite is no longer in service.
** US Space Command, previously known as the NORAD Object No.; also referred
to as the NASA catalog number.
HISTORY OF BLOCK I SATELLITES AND STATUS
SVN01/PRN04 Launched 22 FEB 78; usable 29 MAR 78; no longer in service. Last onboard frequency standard failed 17 Jul 85, 1730 UT.
SVN02/PRN07 Launched 13 May 78; usable 14 JUL 78; no longer in service. L1 signal power permanently turned off in week 8-12 FEB 88.
SVN03/PRN06 Launched 06 OCT 78; usable 13 NOV 78; no longer in service. Operations terminated 18 MAY 92 at 2341 UT.
SVN04/PRN08 Launched 10 DEC 78; usable 08 JAN 79; no longer in service. Crystal oscillator activated 27 OCT 86, 2105 UT. L-band permanently turned off on 14 OCT 89, 1857 UT. L-band enabled 20 FEB 90 1615 UT for testing; disabled sometime in MAY 1990.
SVN05/PRN05 Launched 09 FEB 80; usable 27 FEB 80; no longer in service. Turned off 11 MAY 84.
SVN06/PRN09 Launched 26 APR 80; usable 16 MAY 80; no longer in service. Operations terminated 06 MAR 91, 0342 UT.
SVN07 Unsuccessful launch 18 DEC 81
SVN08/PRN11 Launched 14 JUL 83; usable 10 AUG 83; no longer in service. Changed operational frequency std from Cs to Rb 4 APR 92. Changed operational frequency std to its last usable Rb between 29 Sep 92 1943 UT to 6 Oct 92 1430 UT.Set unusable 04 MAY 93 at 0020 UT and will not return to service.
SVN09/PRN13 Launched 13 JUN 84; usable 19 JUL 84; no longer in service. Changed operational frequency std from Cs to Rb during period 30 Sep 93 to 09 Oct 93. Unusable 4 Nov 93 1640 UT to 13 Dec 93 2130 UT for maintenance. Unusable beginning 28 Feb 94 1345 UT due to end of life testing; PRN13 was boosted to a higher orbit for disposal on 20 Jun 94 at 1817 UT
SVN10/PRN12 Launched 08 SEP 84; usable 03 OCT 84; no longer in service. Changed operational frequency std from Cs to Rb 6 FEB 92. Unusable beginning 18 Nov 95 1845 UT due to end of life testing; PRN12 was boosted to a higher orbit for disposal on 26 Mar 96 (NANUs 242-95325, 051-96086).
SVN11/PRN03 Launched 09 OCT 85; usable 30 OCT 85; no longer in service. Set unusable since 27 Feb 94 0233 UT and permanently set unusable 13 Apr 94 1500 UT due to navigation payload shutdown in preparation for final disposal. PRN03 was thrust out of orbit 14 Apr 94 2100 UT.
REPOSITIONING MANEUVERS
1. Reconfiguration of Block I satellites to a five-vehicle constellation that optimized continental US system performance occurred October 29, 1986 to October 22, 1987 with the repositioning of PRN03/SVN11 to another in-plane location.
2. Reconfiguration of the GPS constellation to increase two-dimensional(2-D) and three-dimensional (3-D) capabilities occurred March 15, 1990 to December 20, 1990. The Block I satellites involved in the maneuver were: PRNs 3 and 11. The Block II satellites involved in the maneuver were: PRNs 2, 14, 16, 18 and 19.
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File gpsb1.txt
last updated: Fri Apr 12 23:05:00 UTC 1996
