For a summary of the Iridium launch sequence, see my Iridium Launch Chronology.
For a summary of the current Iridium constellation situation, see my Iridium Constellation Status.
This is an attempt to summarise, in chronological order, the Iridium satellites that have failed.
Iridium 21 (24873, 1997-034E) (latterly
known as Iridium 921) was
launched on 1997 July 9, but failed to reach operational orbit.
The failure of this satellite was acknowledged by Motorola on
1997 July 21.
See Iridium: one less at http://www.sat-net.com/listserver/sat-nd/msg00311.html
Iridium 27 (24947, 1997-051D)
was launched on 1997 September 14, but failed to reach
operational orbit. The failure of this satellite was acknowledged
by Motorola on 1997 October 22.
See Second iridium failure at http://www.sat-net.com/listserver/sat-nd/msg00366.html
Iridium 20 (24871, 1997-034C) (at
times referred to by OIG as Iridium 18, and latterly known as Iridium
920) was launched on 1997 July 9. The
failure of this satellite was acknowledged by Motorola on 1998
April 23.
See Another Iridium lost in orbit at http://satobs.org/seesat/Apr-1998/0246.html.
Note that historic reports of Iridium 18
tumbling almost certainly refer to this satellite.
Iridium 11 (24842, 1997-030G) (latterly known as Iridium 911) was launched on 1997 June 18, and suffered from various problems which could not be resolved. At one stage it was reported to be "flying backwards".
Iridium 24 (24905, 1997-043C) (later
tracked by OIG as 25105 1997-082B, which are the catalog number
and launch identifier which are proper to Iridium 46) was
launched on 1997 December 20. The failure of this satellite was
acknowledged on 1998 May 8.
Note that historic reports of Iridium 46
tumbling almost certainly refer to this satellite.
Iridium 71 (25320, 1998-026B) was launched on 1998 May 2. It developed problems which could not be resolved.
Iridium 44 (25078, 1997-077B) was launched on 1997 December 8. It later developed problems which could not be resolved.
The failure of Iridium 44 and Iridium 71 was acknowledged by
Motorola on 1998 July 22.
See Two more Iridiums bite the dust at http://www.sat-net.com/listserver/sat-nd/msg00508.html
or Two Iridium satellites with hardware failures
http://satobs.org/seesat/Jul-1998/0298.html
Iridium 14 (24836, 1997-030A) (latterly known as Iridium 914) was launched on 1997 June 18, and later suffered from problems which could not be resolved. "Communication difficulties" with Iridium 14 were acknowledged by Motorola on 1998 September 9. See http://www.flatoday.com/space/explore/stories/1998b/090998e.htm
Iridium 79 (25470, 1998-051D) was launched on 1998 September 8, but failed to reach operational orbit. Iridium 79 decayed on 29 November 2000. (see http://www.satobs.org/seesat/Nov-2000/0256.html)
Iridium 69 (25319, 1998-026A) was launched on 1998 May 2. It later developed problems which could not be resolved.
Iridium 85 (25529, 1998-066C) was launched on 1998 November 6, but failed to reach operational orbit. Iridium 85 decayed on 30 December 2000. (see http://www.satobs.org/seesat/Dec-2000/0409.html)
Iridium 73 (25344, 1998-032C) was launched on
1998 May 17. It entered operational use, but later suffered from
problems which could not be resolved.
The slot in the Iridium constellation previously occupied by
Iridium 73 was taken up by Iridium 75.
Iridium 48 (25107, 1997-082D) was launched on
1997 December 10. It entered operational use, but later developed
problems which could not be resolved. Iridium 48 was forcibly
lowered in April 1999 and decayed on 5 May 2001. (see http://www.satobs.org/seesat/May-2001/0028.html).
The slot in the Iridium constellation previously occupied by
Iridium 48 was taken up by (the second) Iridium 20 (mislabelled
for a long time as Iridium 11).
Iridium 2 (25527, 1998-066A) was launched on 1998 November 6 into orbital plane 5, but was intentionally allowed to drift to become the spare for orbital plane 4. Control was lost while the satellite was being raised on arrival at plane 4, and Iridium 2 has continued to drift.
Iridium 9 (24838, 1997-030C) (at times
referred to by OIG as Iridium 10)
was launched on 1997 June 18. It entered operational use,
but much later suffered from problems which could not be
resolved. Iridium 9 was forcibly lowered in October 2000 and
decayed on 11 March 2003. (see http://www.satobs.org/seesat/Mar-2003/0116.html).
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),
it was acknowledged that "Right now we have had one
failure in 23 months and that's been de-orbited, out of the
orbit. Beginning tomorrow, we will drift one of the spares up
into that slot. That's been the only failure in 23 months and
that's one that was identified quite a long time ago."
The slot in the Iridium constellation previously occupied by
Iridium 9 was eventually taken up by Iridium 84.
See Iridium 9 replacement by Iridium
84
Iridium 38 (25043, 1997-069E) was launched on
1997 November 9. It entered operational use, but evidently lost
its ability to maintain its position in the constellation after
almost 6 years in service.
The slot in the Iridium constellation previously occupied by
Iridium 38 was taken up by Iridium 82.
See Iridium 38 replacement by
Iridium 82.
Iridium 16 (24841, 1997-030F), launched on
1997 June 18, was removed from the operational constellation in
April 2005.
Iridium 86 (25528, 1998-066B) subsequently took its place in the
operational constellation.
See Iridium 16 replacement by
Iridium 86.
Iridium 17 (24870, 1997-034B) evidently failed around August 2005, and Iridium 77 (25471, 1998-051E) took its place in the operational constellation. See Iridium 17 replacement by Iridium 77.
Iridium 74 (25345, 1998-032B), was lowered to the engineering orbit on or about January 10, 2006, while Iridium 21 (25778, 199-032B), one of two spare satellites in orbital plane 1, was raised to operational altitude, presumably to replace it. Iridium 74 evidently remains under control, so is presumably only a partial failure.
Iridium 36 (24967, 1997-056C) evidently failed in service. In early January 2007, Iridium 97 (27450,2002-031A), a spare satellite in orbital plane 4, entered the operational constellation, evidently to replace it. Iridium 36 initially remained close to its nominal position in the constellation.
Iridium 28 (24948, 1997-051E) evidently failed in service. In late July 2008, Iridium 95 (27375, 2002-005D), up till then a spare satellite in orbital plane 3, entered the operational constellation, evidently to replace it. Initially, Iridium 28 remained close to its nominal position in the constellation.
Iridium 33 (24946, 1997-051C) -on February 10, 2009 at 16:56 UT, Iridium 33 (24946, 1997-051C) was in collision with Cosmos 2251 (22675, 1993-036A) . See Iridium 33 collision. Iridium 33 is no longer functional, and appears to have fragmented. Iridium 91 (27372, 2002-005A) subsequently took its place in the operational constellation.
Iridium 23 (24906, 1997-043D) - in early November 2010, Iridium 11 (originally 25577, 1998-074A, but currently labelled by Space-Track as 25578, 1998-074B), previously spare, was raised to the operational orbit, just a few seconds behind Iridium 23 (24906, 1997-043D). This suggested that Iridium 23 must have failed on station. However, in early August 2011, Iridium 11 was moved around the plane, evidently to take over from Iridium 26 (24903, 1997-043A). This suggests that Iridium 23 retained some functionality. On 13 November, 2012, Iridium 94 (27374, 2002-005C), which had been migrating over the previous year from orbital place 3, arrived at orbital plane 2, and was immediately raised to operational altitude to replace Iridium 23 (24906, 1997-043D) which had evidently failed, though retaining at least some functionality. Iridium 23 initially remained at operational altitude a few seconds behind Iridium 94, but was later used to replace Iridium 45 (25104, 1997-02A).
Iridium 26 (24903, 1997-043A) - in early August 2011, Iridium 11 (originally 25577, 1998-074A, but currently labelled by Space-Track as 25578, 1998-074B), which had apparently taken over from Iridium 23 (24906, 1997-043D) in November 2010, was moved around the plane, evidently to take over from Iridium 26 (24903, 1997-043A). This suggests that Iridium 26 must have failed on station.
Iridium 4 (24796, 1997-020E) ceased to maintain its position in the constellation from mid-2012. It was later replaced by Iridium 96 (27376, 2002-005E).
Iridium 29 (24944, 1997-051A) ceased to maintain its position in the constellation in early 2014, and has presumably failed. There was no spare available in plane 3 to replace it, but Iridium 45 (25104, 1997-082A) started migrating from orbital plane 2 towards orbital plane 3, presumably to replace it
Iridium 42 (25077. 1977-077A) evidently failed at the end of August 2014. Iridium 98 (27451, 2002-301B) , which had been spare in orbital plane 6 since migrating from plane 4, was raised to operational altitude to replace it. Iridium 42 has since been reported to be flashing.
Iridium 63 (25286. 1998-021B) evidently failed at the end of August 2014. Iridium 14 (25777, 1999-032A) , which had been spare in orbital plane 1 since launch, was raised to operational altitude to replace it.
In early October 2014, Iridium 51 (25262, 1998-018A), which had been paired wth Iridium 7 (24793, 1997-020B) was moved within orbital plane 4 to be paired with Iridium 6 (24794. 1997-020C).This suggests that Iridium 6 must have a failure considered more serious that that of Iridium 7.
In May 2016, Iridium 57 (25273, 1998-019B) began to drift away slowly from its nominal position and has presumably failed. See Iridium 57 looks to have a bad attitude.
In June 2016, Iridium 15 (24869, 1997-034A) was moved from Plane 6, Slot 7 to Plane 6, Slot 4, replacing Iridium 39 (25042, 1997-069D). The intention may have been to swap over the two satellites but, in any case problems were experienced with with Iridium 39, which was then removed from the operational constellation, leaving a gap. No spare was available to replace it.
In their quarterly report dated 30 June, 2016, Iridium Satellite LLC acknowledged the failure of two satellites in the preceding quarter year.
Sometime prior to November 2017, Iridium 7 (24793, 1997-020B), which was already a partial failure and had been supplemented for some time by Iridium 51, began drifting away from Plane 4, Slot 7.
Sometime prior to January 2018. Iridium 22 (24907, 1997-043E), which occupied Plane 2, Slot 1 had evidently failed on station.
Note: Iridiums 11, 14, 20 and 21 are the second (replacement) satellites known by those names. They were previously known as 11a, 14a, 20a and 21a respectively. Iridiums 911, 914, 920, 921 are the (failed) satellites originally known as 11, 14, 20 and 21 respectively.
The following failed Iridium satellites have decayed:
Iridium 79 (25470, 1998-051D) decayed on 29 November 2000
(see http://www.satobs.org/seesat/Nov-2000/0256.html)
Iridium 85 (25529, 1998-066C) decayed on 30 December 2000
(see http://www.satobs.org/seesat/Dec-2000/0409.html),
Iridium 48 (25107, 1997-082D) decayed on 5 May 2001
(see http://www.satobs.org/seesat/May-2001/0028.html),
and
Iridium 27 (24947, 1997-051D) decayed on 1 February 2002
(see http://www.satobs.org/seesat/Feb-2002/0002.html)
Iridium 9 (24838, 1997-030C) decayed on 11 March 2003
(see http://www.satobs.org/seesat/Mar-2003/0116.html)
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 remained 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 was operational, and 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 was operational, and 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.