Iridium Launch Chronology

Launches of satellites forming the Iridium constellation
showing launch identities and catalog numbers

For a summary of the current situation, see my Iridium Constellation Status page.

The Iridium satellites operate in near-polar orbits at an inclination of 86.4 to the equator, and in are grouped into 6 orbital planes at approximately 31.6 separation, leaving a smaller gap of around 22 at the "seams" between plane 6 and plane 1 where the satellites in adjacent planes are travelling in opposite directions.

The satellites were launched in groups of 2, 5 or 7:

Launch  Orbital Launch
Date    Plane	Id     A     B     C     D     E     F     G
1997/05/05  4  97020   8     7     6     5     4
                      24792 24793 24794 24795 24796
1997/06/18  5  97030  14    12     9    10    13    16    11
                      24836 24837 24838 24839 24840 24841 24842
1997/07/09  6  97034  15    17    20    18    21
                      24869 24870 24871 24872 24873
1997/08/21  2  97043  26    25    24    23    22
                      24903 24904 24905 24906 24907

A demonstration launch of two dummy Iridium satellites took place in September 1997:

1997/09/01     97048  24925 24926
(these dummy satellites are omitted from my status table)
1997/09/14  3  97051  29    32    33    27    28    30    31
                      24944 24945 24946 24947 24948 24949 24950
1997/09/27  4  97056  19    35    36    37    34
                      24965 24966 24967 24968 24969
1997/11/09  6  97069  43    41    40    39    38
                      25039 25040 25041 25042 25043
1997/12/08  6  97077  42    44
                      25077 25078
(this launch completed the intended complement of 11 plus 1 spare in orbital plane 6)
1997/12/20  2  97082  45    46    47    48    49
                      25104 25105 25106 25107 25108
1998/02/18  5  98010  52    56    54    50    53
                      25169 25170 25171 25172 25173
(this launch completed the intended complement of 11 plus 1 spare in orbital plane 5)
1998/03/25  4  98018  51    61
                      25262 25263
(this launch completed the intended complement of 11 plus 1 spare in orbital plane 4)
1998/03/30  3  98019  55    57    58    59    60
                      25272 25273 25274 25275 25276
(this launch completed the intended complement of 11 plus 1 spare in orbital plane 3)
1998/04/06  1  98021  62    63    64    65    66    67    68
                      25285 25286 25287 25288 25289 25290 25291
1998/05/02  2  98026  69    71
                      25319 25320
(this launch completed the intended complement of 11 plus 1 spare in orbital plane 2)
1998/05/17  1  98032  70    72    73    74    75
                      25342 25343 25344 25345 25346
(this launch completed the intended complement of 11 plus 1 spare in orbital plane 1)

At this stage, the originally intended full complement of 66 satellites plus 6 in-orbit spares had been launched. However, by this time, a number of satellites had failed, so further launches were needed to replace the failures and to supplement the spares.

1998/08/19  2  98048   3    76
                      25431 25432
1998/09/08  6  98051  82    81    80    79    77
                      25467 25468 25469 25470 25471
1998/11/06  5  98066   2    86    85    84    83
                      25527 25528 25529 25530 25531
1998/12/19  2  98074  11a   20a
                      25577 25578
1999/06/11  1  99032  14a   21a
                      25777 25778

Eurockot conducted a demonstration launch of two dummy satellites in May 2000. While not specifically part of the Iridium program, the inclination of the target orbit matches with the Iridium constellation:

2000/05/16     00026  26365 26366
(these dummy satellites are omitted from my status table)

Even after the Iridium system was rescued, it was a considerable time before further launches took place to replenish the on-orbit spares.

2002/02/11  3  02005  90    91    94    95    96	(but note designation change made on January 1, 2006)
                      27372 27373 27374 27375 27376
(Iridium 90 was later moved to oribital plane 5, Iridium 94 was later moved to orbital plane 2, and Iridium 96 was later moved to orbital plane 4)
2002/06/20  4  02031  97    98  
                      27450 27451
(note that Iridium 98 was later moved to oribital plane 6)

Iridiums 11a, 14a, 20a and 21a listed above are now known as 11, 14, 20 and 21 respectively, the second (replacement) satellites known by those names (see below).
The original Iridiums 11, 14, 20 and 21 listed above later failed and are now known as 911, 914, 920, and 921 respectively.

Note that the identities of various members of the Iridium constellation have been confused at various times in the past.
Some interchanges of identities seems to have become permanent:
Iridium 24 is tumbling, and correctly labelled by Spacecom as Iridium 24, and correctly tracked, but under 25105 (1997-082B) which are the catalog number and launch identifier which originally belonged to Iridium 46.
Iridium 46 is operational, and correctly labelled by Spacecom as Iridium 46, and correctly tracked, but under 24905 (1997-043C) which are the catalog number and launch identifier which originally belonged to Iridium 24.
Iridium 11 is operational, and is now correctly labelled by Spacecom as Iridium 11, and correctly tracked, but under 25578 (1998-074B) which are the catalog number and launch identifier which originally belonged to (the second) Iridium 20.
Iridium 20 is operational, and is now correctly labelled by Spacecom as Iridium 20, and correctly tracked, but under 25577 (1998-074A) which are the catalog number and launch identifier which originally belonged to (the second) Iridium 11.

SPACECOM exchanged the labelling of Iridium 90 and Iridium 91 on January 1, 2006. The object being tracked under catalog number 27372 (spare in orbital plane 3 until brought into operational use to replace Iridium 33) is now known as "Iridium 91" rather than "Iridium 90", while the object with catalog number 27373 (migrated from orbital plane 3 to orbital plane 5) is now known as "Iridium 90" rather than "Iridium 91". This evidently addressed a long-standing mislabelling of these objects to bring the designations in line with those used by the operators of the Iridium system.

At the Iridium Satellite LLC press conference call on 12 December 2000
(see http://www.ee.surrey.ac.uk/Personal/L.Wood/constellations/iridium/conference-call-Dec-2000.html), plans were announced to launch further spare satellites for the constellation:
"We'll be launching seven more in the next year or so. We have the first launch scheduled for next June, June of 2001. That will be a Delta 2 launch; we'll be putting five spare satellites into orbit. The following spring, roughly March of 2002, we'll be launching two more and in that case we'll be using the Russian rocket. So we will inject seven more spares into the system, so we'll have more than two spares in each orbit, and that will give us the life that we believe is there."
These launches were in fact delayed until 2002.

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