** Updated 08 September 2014 **
For a summary of the Iridium launch sequence, see my Iridium Launch Chronology. There is now also a summary of Iridium Failures.
Latest changes (see below for earlier changes):
*** At the end of August 2014, Iridium 98 (27451, 2002-301B) , whch had been spare in orbital plane 6 since migrating from plane 4, was raised to operational altitude a few seconds behind Iridium 42 (25077. 1977-077). It is so far unclear whether Irdium 42 has failed.***
Orbital <-------- Operational satellites --------> Spares Plane Plane 1: 21 72 75 70 62 63 64 65 66 67 68 14; 74 (note: Iridium 74 is probably a partial failure) Plane 2: 22 94 76 25 23 46 47 20 49 11 3 45 (migrating to plane 3?) (note: Iridium 23 is probably a partial failure) Plane 3: 55 95 31 30 32 91 57 58 59 60 (note: Iridium 29 has evidently failed) Plane 4: 19 34 35 97 5 6 51/7 8 96 37 61 Plane 5: 50 56 52 53 84 10 54 12 13 83 86 90 (launched to plane 3, but has been migrated to plane 5) Plane 6: 18 42/98 40 39 80 77 15 81 82 41 43
Original <----- Failed -----> <- Failed -> Note that some of the failed satellites have drifted from the original orbital planes Orbital (but still in orbit) (decayed) Plane Plane 1: 73t Plane 2: 69t 24t 71t 26 48d Plane 3: 28 29 33t 27d Iridium 33 was fragmented by the collison with Cosmos 2251 on February 10, 2009 Plane 4: 4 36t Plane 5: 2t 914t 911t 16t 85d 9d Iridium 2 has drifted far from its original launch plane, and continues to drift Plane 6: 920t 921t 44t 38t 17t 79d
t indicates satellites that have been reported as tumbling out of control.
This is Rod Sladen's personal opinion of the status of the Iridium constellation, and the information herein has not been confirmed by the new owners, Iridium Satellite LLC, nor by Boeing who are maintaining the system for them.
Iridium 11 (until recently referred to by OIG as Iridium 20), Iridium 14, Iridium 20 (until recently referred to by OIG as Iridium 11) and Iridium 21 are the second (i.e. replacement) satellites known by those names. They were previously known as Iridium 20a, Iridium 14a, Iridium 11a and Iridium 21a respectively.
Iridium 911, Iridium 914, Iridium 920, Iridium 921 are the (failed) satellites originally known as Iridium 11, Iridium 14, Iridium 20 and Iridium 21 respectively.
d indicates satellites that have already decayed:
Iridium 79 (25470, 1998-051D) decayed on 29 November 2000
Iridium 85 (25529, 1998-066C) decayed on 30 December 2000
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
Iridium 9 (24838, 1997-030C) decayed on 11 March 2003
Iridium 5 and Iridium 51 were confused during August 2001.
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.
At the end of August 2014, Iridium 98 (27451, 2002-301B) , whch had been spare in orbital plane 6 since migrating from plane 4, was raised to operational altitude a few seconds behind Iridium 42 (25077. 1977-077). It is so far unclear whether Irdium 42 has failed.
By early 2014, Iridium 45 (25104, 1997-082A) is no longer maintaining its place in orbital plane 2. Iridium 45 appears to be migrating towards orbital plane 3. Its place in orbital plane 2 has been taken by Iridium 23 (24906, 1997-043D).
By early 2014, Iridium 29 (24944, 1997-051A) had ceased to maintain its position in the constellation, and had presumably failed. At that tme, there was no spare available in plane 3 to replace it..
On 20 November, 2012, Iridium 96 (27376, 2002-005E), previously spare in orbital place 3, began migrating towards orbital plane 4, which had no on-orbit spare, This left orbital place 3 without a spare. The migration took around twelve months. Iridium 96 took over from failed Iridium 4 (24796, 1997-020E). Iridium 96 was raised to operational altitude several months before its arrival in plane 4 and appears to have been brought into use at that time.
On 13 November, 2012, Iridium 94 (27374, 2002-005C), which had been migrating over the past 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).
In mid 2012, Iridium 4 (24796, 1997-020E) ceased to maintain its position in the constellation. At that time, Plane 4 had no on-orbit spare
In late July 2012, Iridium 51 (25262, 1998-018A). which had been out of the operational constellation for many years, was moved in the postion previously occupied by Iridium 7 (24793, 1997-020B), while Iridum 7 was moved to follow slightly behind it. The two satellites are each providing some of the functionality for the given slot. Orbital Plane 4 has no other spare satellite.
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, and also that Iridium 23 retained some functionality.
Orbital Plane 2 had no other spare satellite, but Iridium 94 (27374, 2002-005C) was in process of migrating from Orbital Place 3.
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 suggests that Iridium 23 must have failed on station, but possibly only partially.
In early March 2009, Iridium 91 (27372, 2002-005A) [note that some sources still label this satellite as Iridium 90] was raised to the operational orbit to fill the gap left by the loss of Iridium 33.
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.
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 Iridium 28 (24948, 1997-051E). Initially, Iridium 28 remained close to its nominal position in the constellation, so had presumably failed on station.
(January 2008) Iridium 90 [previously labelled as Iridium 91] which had been manouvering since mid October2005 has arrived in orbital plane 5
(May 2007) Iridium 98, which had been manouvering since late June 2005, has arrived in orbital plane 6
In early January 2007, Iridium 97 (27450,2002-031A), a spare satellite in orbital plane 4, entered the operational constellation, evidently to replace Iridium 36 (24967, 1997-056C). Iridium 36 initially remained close to its nominal position in the constellation - it had evidently failed on station.
On or about January 10, 2006, Iridium 21 (25778, 199-032B), one of two spare satellites in orbital plane 1, was raised to operational altitude, presumably to replace Iridium 74 (25345, 1998-032B),. which was lowered to the engineering orbit. It is unclear whether Iridium 74 has failed completely
On January 1, 2006, the Spacecom labelling of Iridium 90 and Iridium 91 was interchanged. There was no change to the operational constellation.
In August 2005, Iridium 17 evidently failed, and Iridium 77 took its place in the operational constellation. This left orbital plane 6 without a spare satellite.
In April 2005, Iridium 16 was removed from the operational constellation, and subsequently Iridium 86 took its place in the operational constellation. This left orbital plane 5 without a spare satellite.
On January 29, 2004, the OIG/Spacecom labelling of Iridium 11 and Iridium 20 was
There was no change to the operational constellation.
Iridium 82 replaced Iridium 38 in orbital plane 6 on or about September 17, 2003.
Iridium 30 and 31 exchanged places in the constellation on September 19-22, 2002.
2 further spares (Iridium 97 and 98) were launched at 0933 UT on 20 June 2002 from Plesetsk Cosmodrome by Eurockot.. This launch was directed at orbital plane 4. Iridium 98 was subesquently moved to orbital plane 6.
5 additional spare Iridium satellites (Iridium 90, 91, 94, 95 and 96) were launched from Vandenberg AFB aboard a Delta II rocket on 11 February 2002 at 17:43:44 UT. The originally intended launch on 8 February 2002 at 18:00:30 UT was scrubbed at the last moment, while the launch opportunities on 9 February 2002 at 17:54:55 UT and 10 February 2002 at 17:49:19 UT also had to be scrubbed. See http://www.boeing.com/news/releases/2002/q1/nr_020211s.html and http://spaceflightnow.com/delta/d290/status.html for more details on the launch. This launch was directed at orbital plane 3, which previously had no spares. Perhaps surprisingly, there was initially no indication that it was intended to drift some of the spares to other orbital planes. However, Iridium 90 (initially labelled as Iridium 91) was subesquently moved to orbital plane 5, and Iridium 94 was later moved to orbital plane 2. Iridium 96 is now being moved towards plane 4.
@ Iridium 5 and Iridium 51 were confused during August 2001.
The previous change to the operational constellation was the replacement of Iridium 9 by Iridium 84.
Iridium 2 has drifted far from its original orbital plane (as have several of the tumbling satellites). At one time, it was deliberately allowed to drift to become the spare in another plane (plane 4?), but it evidently failed on arrival in the new plane, and continues to drift out of control.
At the Iridium Satellite LLC press conference call on 12
(see http://www.ee.surrey.ac.uk/Personal/L.Wood/constellations/iridium/conference-call-Dec-2000.html), a figure of 8 operational spares was quoted. This would include Iridium 82, 84 and 86 which have since become operational.
Also at the Iridium Satellite LLC press conference call on 12
(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.