Friday, 6 August 2021

A weird Navigational Warning for a mass deorbit on August 9-10? [updated]

click map to enlarge

A weird Navigational Warning (NAVAREA XII 384/21) for "Space Debris" has appeared defining nine areas, some of them overlapping, in the Pacific for August 9, 16:27 to 17:29 UT and August 10, 17:16 to 18:17 UT.

I have mapped them in the map above. Below is the text of the Navigational Warning:

060929Z AUG 21
   091627Z TO 091729Z AUG, ALTERNATE
   101716Z TO 101817Z AUG
   A. 22-52-40N 137-34-57W, 20-12-47N 134-02-08W,
      04-25-05N 146-28-48W, 06-54-48N 149-55-52W.
   B. 51-11-05N 141-36-54W, 49-40-18N 142-13-53W,
      50-44-15N 170-19-30W, 52-17-11N 170-39-50W.
   C. 12-58-15N 130-00-21W, 10-52-28N 127-06-04W,
      05-17-31S 138-47-34W, 03-13-54S 141-40-25W.
   D. 48-12-47N 135-38-42W, 46-20-17N 136-55-43W,
      50-55-14N 165-28-28W, 52-59-09N 165-19-24W.
   E. 13-53-47N 126-52-33W, 11-46-05N 123-56-09W,
      04-19-41S 135-37-56W, 02-14-45S 138-32-32W.
   F. 49-27-33N 135-51-45W, 47-43-47N 136-53-00W,
      50-56-51N 168-09-57W, 52-48-04N 168-20-28W.
   G. 14-27-06N 127-19-28W, 12-18-52N 124-23-30W,
      03-36-29S 136-03-34W, 01-31-24S 138-57-30W.
   H. 49-46-04N 136-40-41W, 48-05-08N 137-37-30W,
      50-55-01N 168-54-51W, 52-42-19N 169-08-13W.
   I. 31-49-12N 124-20-42W, 30-20-18N 122-34-43W,
      22-47-14N 130-25-52W, 24-10-15N 132-10-44W.
2. CANCEL THIS MSG 101917Z AUG 21.

The nine areas A to I cluster in basically three regions (which I have colour-coded in the map above).

The directions of the areas point to a series of deorbits from a 51-53 degree inclined Low Earth orbit. As I have indicated in the map in top of this post, two of the three defined regions with warning boxes line up with the ISS groundtrack during the two time windows given, but I think this is coincidence (and the series of boxes south of Alaska do definitely not line up with the ISS during these two time windows. In fact, this points to deorbits from at least two different orbital planes).

Rather, my suspicion is a mass deorbit of Starlink satellites, who move in ~53 degree inclined orbits [but see update below].


After some discussion, Jan Hindrik Knot rightfully questioned whether Starlink satellites, with their ion thruster propulsion, are capable of a controlled deorbit in a designated area at all. That is a good point, which I overlooked initially.

So it appears we have no idea what will be deorbitted on August 9-10.

The combination of the areas in the mid-Pacific and those south or Alaska, to me point to deorbits from at least two different orbital planes (both inclined 51-53 degrees).

Note that, from the position of the areas, the fact that their shapes clearly point to deorbits from Low Earth Orbit, and that the NavWarning mentions time windows on two successive dates, it is clearly not related to this deorbit  (the Spectr-R rocket booster) from Deep Space either.


The plot thickens: the on-line KML version of the Navigational Warning has appeared and mentions: 

"Authority: NASA 300917Z JUL 21"

(the versions sent to subscribers to the service doesn't mention the authorities issuing the warnings).

So it appears to be something NASA-related (HT to @john_moe on Twitter).

One possibility could be that these are emergency landing zones for Starliner (which was to be launched on July 30, the date mentioned in the "Authority:" line: but was scrubbed). Still open questions though: why August 9 and 10? Why where these same zones not published before the July 30 launch date? Questions, questions...


I like the suggestion by Bob Christy that these are warnings for the reentry of the Starliner service module (that is jetissoned from the Starliner capsule before landing of the latter). That makes sense.

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