Orbital Focus - International Spaceflight Facts and Figures
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Launches and Orbital Operations

Tyneside, UK
2024 May 20
Monday, Day 141

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Mission Events 2022:

Mission Events 2021:

Mission Events 2020:



Hidden Changes to Space-Track Catalogue



The Catalogue at the Space-Track website records administrative and descriptive details of every space object that receives a Catalogue Number. It is searchable for things such as all objects recorded against a specific launch, types of objects on a launch or launch site.

Alongside the Catalogue, Space-Track offers a searchable list of catalogue changes so it is possible to track the evolution of an object's name from initial anonymity through being renamed 'Object x', to allocation of an actual name. If the name needs to be corrected, it too appears in the Change list.

Just as 'nature abhors a vacuum', the designation of a rocket body or debris item as the 'A' object from a launch, and its occupation of the lowest Catalogue Number is anathema - and the system breaks down as a result.

Yaogan 36 Group 2

As with most launches, the initial naming of items from this one was 'Object A' through to 'Object E'. A stream of orbit data followed each object as shown in the plot above. The three satellites soon revealed themselves by firing thrusters and adjusting their orbits. They were objects B, E and D. That left A and C as the rocket body and a debris item.

A full two weeks after launch, the cataloguers realised that 133A was not an active satellite. They sprang into action and switched round the data streams for 133A (the rocket) and 133E (a satellite) to get rid of the the perceived anomaly. The change be seen as the X-shaped crossover on the plot.

Rockets as Catalogue Object A

There are twenty eight launches out of around 2400 in the Catalogue where a rocket body has the 'A' designation. The most recent is 2021-082A, a Falcon 9 that launched a group of Starlink satellites. It did not actually receive its name until several hours after it re-entered and the re-entry was formally recorded. A flip of IDs at that point would have resulted in the new 2021-082A having a permanent record showing it simultaneously as having re-entered and being in orbit.

1996-064A and 2016-042A are listed as rocket bodies. The former was the only item catalogued from that particular launch, other items departed Earth orbit in the direction of Mars and weren't catalogued. 2016-042A had an experimental re-entry vehicle attached that only separated after retro-fire.

Before those two, we have go back over fifty years to 1971 and earlier to see 'A' designated rocket bodies.

There are no obvious records of a debris item being catalogued as an A object.

Launch 2021-058

This was launch of six satellites by Virgin Orbit using its LauncherOne rocket. 2021-058A is currently catalogued as 'Object A' with type 'Unknown'.

From information provided by Space-Track, it has a large Radar Cross Section. All other 2021-058 objects have small RCS and are named and described as satellites. Other LauncherOne missions have a similar slate of catalogued items but the Large RCS object is listed as a rocket body.

To identify 2021-082A as a rocket body would break the convention and, sixteen months down the line, switching IDs around would really mess things up. The object type remains as 'Unknown'.

Why Does This Matter?

Well - the new identities only apply to orbit data published from than point onwards. Earlier records retain the old Catalogue Number and Designation. The event is not recorded as a catalogue change so there is nothing to show what happened.

It's not uncommon in the first few hours of an object's life on orbit for this sort of change to happen while tracking sensors and software try to distinguish between items in a group of closely-orbiting objects. Researchers and diarists understand this and work round it. Name allocation seldom happens before such switching-around settles down.

But - this change happened TWO WEEKS after launch and was driven by a decision based on administrative convention. The record will now show that 2022-133E is catalogued as an inert rocket body. Launched on October 14, it apparently raised orbital altitude by nearly three kilometres on October 26. This is is patently untrue and distorts the historical record.


Space-Track has a history of change for its own convenience/whim without understanding how its users work. Examples:

          ceasing to publish TLE Set Numbers because 'someone' found it confusing, so tough luck
          on people who found it useful,

          rowing back on discontinuing TLE publication for Catalogue Numbers above 70,000 when
          important users said they couldn't immediately cater for it,

          extending indefinitely a recent two-week deadline for changing some download formats
          because 'key customers' were not warned in advance.

These things will keep happening until Space-Track actually connects with its users in a meaningful way. For the same reason, subtle and unnanounced changes like this one will continue.

Page Date - 2022 Oct 27

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