Saturday, 16 September 2023

PAN is on the move again

click image to enlarge


In a recent post I mentioned that I recovered the enigmatic SIGINT satellite PAN/NEMESIS-1 (2009-047A) - we had lost sight of it for about a year - and that it appeared to be stationkeeping at 39.9 E, not far from Express AM-7, when I recovered it mid-August.

It was definitely in a stable position near Express AM-7 in August: but my most recent observations show that PAN has started to drift again, westward. This drift probably was initiated somewhere between September 7 and September 10, 2023, with a drift rate of about 0.16 degrees/day.

Above are four images, from August 22, August 27, September 10 and September 15, 2023 (they are 10 second exposures made by me from Leiden, the Netherlands with a ZWO ASI 6200MM Pro and Samyang 1.2/85 mm lens). If you look at the position of PAN relative to the neighbouring satellites, it is clear that it was stationary between August 22 and August 27, but started to drift after that.

PAN/NEMESIS-1 is a SIGINT satellite with an unusual history of frequent moves in position, and each time it moved it was being positioned very close to a commercial telecommunication satellite

From it's launch in 2009 until mid 2013, it was repositioned each few months (see my 2016 article in The Space Review). 

After mid 2013 it stopped moving and was steady at 47.7 E for many years: untill it started to move again in early 2021. 

Our coverage of it has been a bit spotty since that time (with an almost a year long coverage gap between 20 October 2022 and 22 August 2023, when I recovered it again). below is an updated diagram of it's relocations since it's launch in 2009:


click diagram to enlarge


The frequent moves between 2009 and 2013 had to do with the unique role of PAN/NEMESIS-1 in the drone war at that time: see this in-depth 2016 article about satellites and the drone war in The Intercept, and my 2016 article in The Space Review for the details.


PAN launch patch (collection author)

Friday, 15 September 2023

The upcoming (?) reentry of Kwangmyŏngsŏng 3-2 (KMS 3-2), North Korea's last remaining satellite

KMS 3-2 (image: KCNA)

Somewhere this week, North Korea's last remaining - albeit probably not functional - satellite on orbit, Kwangmyŏngsŏng 3-2 (KMS 3-2, 2012-072A), will reenter (or has it already? See later...).

Kwangmyŏngsŏng 3-2 was launched on 12 December 2012 and was North Korea's first succesful satellite launch. Following in the footsteps of a later launch, KMS 4 from 2016 which reentered earlier this year on 30 June 2023, it is now set to have an uncontrolled reentry. 

With this, North Korea will lose the last satellite they have on orbit (the UNHA-3 upper stage of this launch is still on orbit).

It is not clear whether KMS 3-2, said to be a remote sensing satellite to monitor crops and weather, was ever functional. To my knowledge, no independent reception of signals from the payload has ever been reported.

Unfortunately, orbital updates for KMS 3-2 stopped to appear in the CSpOC catalogue after September 12. The last available orbit has epoch 12 Sept 2023 15:20:30 UTC. My reentry forecast based on that orbit was 16 Sept 2023 18:00 UTC ± 20 hrs.


click diagram to enlarge


A TIP was not issued (it wasn't for KMS-4 either at the time), but a reentry notice was suddenly added to the KMS 3-2 entry in the CSpOC SATCAT on Sept 15, stating 13 September 2023 as the reentry date.

I think that date is not correct, and merely an 'administrative decay'  - meaning they either don't really know, or are not willing to share, when it really reentered. 

The last known orbit from September 12 is a 226 x 235 km orbit and even using extremely high values for solar activity (higher than they in reality were) I can't get it to reenter earlier than Sept 15-16 in my GMAT model, nor in SatEvo. I simply don't see it coming down from that altitude within a day, unless something drastic happened (e.g. a structural disintegration of the satellite before the actual reentry). For reference, it took KMS 4 some four-and-a-half days to come down from that altitude and reenter in June.


click diagram to enlarge


So it looks like either CSpOC lost the object and doesn't really know, or they do not want to to share the last whereabouts of KMS 3-2 (e.g. from a notion that this would help the North Koreans in some way).

Meanwhile, after two failed launch attempts the past months using a new carrier rocket, North Korea said it will attempt to loft a new satellite into orbit in October.

I recently talked to the website North Korea News about the upcoming KMS 3-2 reentry, which you can read here.

Firefly Alpha 'Victus Nox' Rapid Response launch [UPDATED]


click to enlarge

On September 15 at 2:28 UTC, Firefly Aerospace succesfully launched a Firefly Alpha rocket from SLC-2 at Vandenberg Space Force Base in California. It carried 'Victus Nox', a small satellite, as a Rapid Response launch exercise. 

The latter is a program where a payload is launched with a very short notice (60 hours) during which the carrier rocket and payload have to be readied and launched.

Navigational Warnings for the launch appeared on September 14. They point to launch into a ~97.8 degree inclined Sun-synchronous orbit (see map above).

140310Z SEP 23
NAVAREA XII 631/23(17,18,19).
   A. 150157Z TO 150319Z SEP, ALTERNATE
      160157Z TO 160319Z SEP IN AREA BOUND BY
      25-50.00N 126-00.00W, 26-00.00N 126-35.00W,
      25-28.00N 126-51.00W, 24-59.00N 125-50.00W,
      25-31.00N 125-33.00W.
   B. 150406Z TO 150413Z SEP, ALTERNATE
      160406Z TO 160413Z SEP IN AREA BOUND BY
      46-21.00N 143-08.00W, 28-18.00N 147-24.00W,
      27-54.00N 146-22.00W, 46-06.00N 141-21.00W.
2. CANCEL THIS MSG 160513Z SEP 23.//

Firefly Aerospace announced on September 15 that the launch was successful. Some imagery of te launch is here.



An object has now been catalogued by CSpOC as nr 57861 (2023-142A) in a 97.32 deg inclined, 476 x 531 km sun-synchronous orbit:


click image to enlarge

It has a slightly lower orbital altitude than I estimated and 0.5 degree lower orbital inclination:

click image to enlarge

Sunday, 10 September 2023

Recovering USA 310, PAN and Trumpet 2


click image to enlarge

Our coverage of classified objects in high altitude orbits has been waning over the past few years. In February, I made a first attempt to recover some. In the past two weeks, I again recovered a number of these objects, as a by product of testing a ZWO ASI6200MM camera (that ultimately is going to be installed on the roof of the Delft Technical University Aerospace faculty).

One of the objects I recovered, is a very unusual one: USA 310 (2020-083A). This object is in an odd 58.5 degree inclined, 11097 x 11074 km MEO orbit. It was launched on 13 November 2020 as NROL-101 (see this 2020 blogpost). We tracked it and it's Centaur upper stage for a couple of weeks, but lost it after February 2021. In other words: it had not been seen for the last 2.5 years!

That is, untill I serendipitously picked it up last August 22, while imaging geostationary satellites. In the imagery, a streak was encountered (see image above). It is a fit with USA 310. I managed to track it again during several nights the past two weeks. Frankly, I am not 100% sure whether it is USA 310 or the Centaur upper stage from that launch, but it does not seem to have the periodic brightness variation the Centaur upper stage showed in 2020/2021. And it is (relatively) bright only in the eastern part of the sky, just like USA 310 back in 2020/2021.

More objects were recovered. Several geosynchronous objects that hadn't been observed for a while, were imaged. One of them, the enigmatic PAN (2009-047A), had moved (just as it used to frequently do in the past, see my in-depth article on PAN in The Space Review from October 2016). I recovered it at longitude 39.7 degrees East, in the vicinity of Express AM-7. Observations over the past two week show it is stationkeeping, so it appears to be still operational (see also this post from 2021, when after several years of being stable at 47.7 E, it started to drift). Below is the recovery image:

click image to enlarge

Coverage of high altitude objects in HEO has likewise become spotty. I observed a number of them late February (see this blogpost), and again did so the past two weeks (a.o. TRUMPET 1 and USA 278). I recovered the SIGINT satellite TRUMPET-2 (1995-034A) on September 5, which had not been seen for almost 2 years:


One reason why I only sporadically track objects in GEO and HEO is that identifying and measuring them is much more labour-intensive than video-tracking objects in Low Earth Orbit, as identifying and measuring is still done manually for these objects by me. One day, I should get myself some software to make this a more easy task...

Wednesday, 6 September 2023

A new test attempt of the LRHW hypersonic missile from Cape Canaveral

click map to enlarge


A few days ago, Navigational Warnings (NAVAREA IV 1030/23) were published that point to a new test launch attempt of the Long Range Hypersonic Weapon (LRHW) from Cape Canaveral in the period 6 - 8 September 2023.

The Navigational Warning delineates seven hazard zones which, just like for the scrubbed test in March, delineate a signature "forked" trajectory (see map above):

041402Z SEP 23
NAVAREA IV 1030/23(GEN).
   A. 28-30.57N 080-33.08W, 28-30.00N 080-27.00W,
      28-27.00N 080-02.00W, 28-20.00N 080-02.00W,
      28-22.00N 080-21.00W, 28-25.18N 080-34.79W.
   B. 28-04.00N 078-49.00W, 28-11.00N 078-47.00W,
      27-43.00N 076-32.00W, 27-31.00N 076-31.00W.
   C. 28-27.00N 080-02.00W, 28-22.00N 079-09.00W,
      28-11.00N 078-47.00W, 28-04.00N 078-49.00W,
      28-03.00N 079-12.00W, 28-20.00N 080-02.00W.
   D. 23-00.00N 060-00.00W, 20-30.00N 060-00.00W,
      22-00.00N 063-00.00W, 24-00.00N 063-00.00W.
   E. 28-30.00N 060-00.00W, 26-00.00N 060-00.00W,
      25-00.00N 063-00.00W, 27-00.00N 063-00.00W.
   F. 28-00.00N 056-00.00W, 30-00.00N 042-30.00W,
      32-00.00N 042-30.00W, 30-00.00N 056-00.00W.
   G. 19-00.00N 057-00.00W, 11-30.00N 041-00.00W,
      13-30.00N 041-00.00W, 21-00.00N 057-00.00W.
2. CANCEL THIS MSG 081941Z SEP 23.

Launch is likely from a TEL on Cape Canaveral pad 46.

The hazard areas are very similar to, but not exactly the same  as, those for the scrubbed March test (areas fro that scrubbed test marked in red in the comparison map below):

click map to enlarge

Meanwhile, at the other side of the United States, a routine test launch of an unarmed  Minuteman-III ICBM from Vandenberg in California to the Reagan Test Range on Kwajalein in the Marshall Islands is also planned for 6-7 September 2023 UTC, according to both a Vandenberg Space Force Base news bulletin and Navigational Warnings published:

click image to enlarge


The hazard zones in the map above come from these two Navigational Warnings:

292100Z AUG 23
   A. 0631Z TO 1337Z IN AREA BOUND BY
      34-38.00 N 121-23.00 W, 34-38.00 N 120-52.00 W,
      34-44.00 N 120-35.00 W, 34-55.00 N 120-35.00 W,
      34-56.00 N 120-57.00 W, 34-56.00 N 121-22.00 W.
   B. 0631Z TO 1326Z IN AREA BOUND BY
      34-20.00 N 124-33.00 W, 34-35.00 N 124-35.00 W,
      34-52.00 N 122-01.00 W, 34-37.00 N 121-59.00 W.
   C. 0631Z TO 1326Z IN AREA BOUND BY
      32-36.00 N 136-04.00 W, 32-49.00 N 136-08.00 W,
      33-01.00 N 135-05.00 W, 32-48.00 N 135-02.00 W.
   D. 0631Z TO 1431Z IN AREA BOUND BY
      13-17.00 N 173-49.00 E, 13-36.00 N 174-20.00 E,
      13-16.00 N 174-33.00 E, 12-57.00 N 174-01.00 E.
2. CANCEL THIS MSG 081531Z SEP 23.

282325Z AUG 23
HYDROPAC 2811/23(81).
DNC 12.
    ALTERNATE 070700Z TO 071411Z SEP
   A. 09-16.00N 167-22.00E, 09-23.00N 167-33.00E,
      09-34.00N 167-26.00E, 09-43.00N 167-33.00E,
      10-09.00N 168-13.00E, 09-31.00N 168-38.00E,
      09-05.00N 167-58.00E, 09-02.00N 167-47.00E,
      08-58.00N 167-33.00E.
   B. 11-51.00N 171-59.00E, 12-37.00N 171-21.00E,
      12-24.00N 170-59.00E, 11-39.00N 171-22.00E,
      10-53.00N 171-58.00E, 11-05.00N 172-20.00E.
2. CANCEL THIS MSG 071511Z SEP 23.



The Minuteman-III test from Vandenberg to Kwajalein has happened, at 6 sept 2023 8:26 UTC, per a Vandenberg SFB news bulletin. According to the Air Force Global Strike Command, the test involved three reentry vehicles.


The test of the LRHW out of Cape Canaveral was aborted, just like earlier in March

Tuesday, 22 August 2023

A new North Korean satellite launch attempt upcoming [UPDATED]

Click map to enlarge

UPDATE (24 Aug 2023)

The launch took place around 18:50 UTC (so at nighttime this time) on August 23. The payload failed to reach orbit.

According to the North Korean State News Agency KCNA, the first and second stages worked nominally (the second stage failed during the May launch), but there was an "error in the emergency blasting system during the third-stage flight".

This sounds like the self-destruct mechanism was triggered by mistake.

KCNA reports that a third launch attempt will be conducted in October. Apparently, they have a lot of spare satellites and rockets in store...

[end of update]

North Korea has issued a Navigational Warning for a new satellite launch attempt from Sohae. The launch window runs from 23 August 15:00 UTC to 30 August 15:00 UTC.

The three hazard areas from HYDROPAC 2699/23 (blue in the map above)  are similar to those for the failed June launch attempt. They are different from the 2016 KMS-4 launch (shown in red in the map above, for comparison)

(more on the failed June attempt in a previous post here, which also discusses the two possible launch trajectories I have depicted in the map).

The text of Navigational Warning HYDROPAC 2699/23:

211953Z AUG 23
HYDROPAC 2699/23(91,92,94).
DNC 11, DNC 23.
   231500Z TO 301500Z AUG IN AREAS BOUND BY:
   A. 36-06.94N 123-33.11E, 35-24.52N 123-22.78E,
      35-20.02N 123-48.62E, 36-02.44N 123-59.18E.
   B. 34-05.90N 123-01.99E, 33-23.47N 122-51.88E,
      33-16.54N 123-29.66E, 33-58.97N 123-40.07E.
   C. 14-54.17N 128-40.10E, 11-19.30N 129-10.84E,
      11-26.81N 129-54.13E, 15-01.70N 129-24.05E.
2. CANCEL THIS MSG 301600Z AUG 23.

Tuesday, 8 August 2023

The reentry of a Soyuz rocket stage over southern Australia on August 7

click map to enlarge


On 7 August 2023 at 13:20 UTC, Russia launched the first of it's improved GLONASS-K2 navigation satellites from Plesetsk Cosmodrome. The launch employed a Soyuz 2.1b rocket with a Fregat upper stage. The payload and the Fregat upper stage were subsequently catalogued in 19156 x 19135 km resp 19182 x 19005 km, 64.8 degree inclined Medium Earth Orbits (MEO), as catalogue numbers 57517 and 57518.

Some 40 minutes after the launch, people from southern Australia and Tasmania were treated to a spectacular sight of a bright slow-moving, fragmenting fireball that crossed the sky. Many eyewitness video's were posted on social media and poicked up by the News media: for a few fine examples see here, here, here and  here. Immediate suspicions were raised that this was space debris.

Indeed, the fireball was the Soyuz 3rd stage reentering the atmosphere. A Navigational Warning for space debris connected to this launch had been published earlier (HYDROPAC 2502/23), for an area south of Australia and Tasmania:

021113Z AUG 23
HYDROPAC 2502/23(75,76).
DNC 05, DNC 06.
   071300Z TO 071600Z AUG, ALTERNATE
   1300Z TO 1600Z DAILY 08 AND 09 AUG
   43-10.00S 148-55.00E, 53-30.00S 163-20.00E.
2. CANCEL THIS MSG 091700Z AUG 23.

The time window matches well with the Australian reentry sighting. The area defined by the Navigational Warning matches a launch into a ~63 degree inclined parking orbit from Plesetsk:

click map to enlarge


The Soyuz 2.1b rocket consists of four side boosters ('stage 1'), a core stage ('stage 2') and a third stage. On top of that is (for this launch) the Fregat upper stage. The Soyuz rocket brings the Fregat upper stage and GLONASS payload in a low parking orbit. From there, a series of firings of the Fregat stage bring the payload to 19150 km Medium Earth Orbit (MEO). The Fregat upper stage is left on orbit, but the Soyuz stages deorbit downrange from the launch site: the last of these stages, is the stage that reentered over southern Australia about half a revolution after the launch.

GLONASS is the Russian equivalent of GPS.

Monday, 26 June 2023

[UPDATED] North Korea's KMS 4 has only a few days left on orbit


[post update nr 8, 4 July 2023  09:40 UTC]

Recently, on May 30, North Korea tried to launch a new satellite. The satellite however did not reach orbit, because the second stage of the launch vehicle failed (see my earlier post here).

There are currently two older North Korean satellites on orbit: KMS 3-2 (launched on 12 December 2012) and KMS 4 (launched on 7 February 2016). One of these, KMS 4, is now very close to reentry.

Kwangmyŏngsŏng 4 (KMS 4, 2016-009A) was launched on 7 February 2016, into a 501 x 465 km, 97.5 degree inclined sun-synchronous orbit. It is said to be an optical reconnaissance satellite, as also implied by its sun-synchronous orbit: but it was never clear whether it ever actually functioned after launch. 

A lot of noise was made in some parts of the US Media back in 2016 about it "tumbling out of control" through space, but optical observations did and do not show clear signs of tumbling.

Over the past 8.5 years, natural orbital decay has lowered the orbit of the satellite, to the point where it at the last available orbit  (orbit epoch 29 June 2023, 21:14 UTC) was down to a 149 x 168 km orbit. The video above was filmed by me on June 14, 2023, and shows the current fast angular movement due to the low orbital altitude.

The diagram below shows the orbital evolution since 1 January this year: it is was coming down fast. At the moment you are reading this, it likely only has a few hours on orbit left it has reentered already.


click diagram to enlarge

[Updated and editted 3 July 2023] My current "aftercast", based on a late published orbit with epoch 29 June 21:14 UTC, is reentry in the early hours of June 30, 2023. The nominal modelled reentry time is 30 June, 03:54 UTC ± 1.4 hr (note the large uncertainty interval, about one full orbit!).

The diagram below shows how the reentry forecasts for KMS 4 were developing with each orbit update.

click diagram to enlarge


With the current still widely uncertain "aftercast", with an uncertrainty of one full orbital revolution, the blue line on the map below is where it could have come down: 


click map to enlarge

Note that this reentry is NOT something to worry about. The reentry will have been harmless: KMS 4 is small, it is a box of about 1 x 0.65 meter with solar panels, weighing maybe 200 kg. It will likely have burned up completely upon atmospheric reentry. Yet because it is a North Korean satellite, the reentry might garner some interest.

[UPDATED] Curiously, CSpOC (18th SPSS) never published a TIP for KMS 4. Early on July 3, 2023, the catalogue listed it as if still on orbit, albeit with days old elements. Late on July 3, a reentry date (but no reentry time) of 30 June 2023 was entered into the catalogue.

Apparently 18 SPSS told Jonathan McDowell (see this tweet) that no TIP was issued because the satellite was "too small" to warrant one. Which is not very believable, as the same week they did issue a TIP for Skysat C18 (2020-057BR), which is of similar size as KMS 4, and TIP's have been issued for even smaller objects in the past....

We are not talking about a cubesat here, KMS 4 was about one meter in size, not counting deployed solar panels.

Perhaps - but this is my speculation only- they wanted to keep the reentry quiet because anything North Korean is accompanied by unbridled panic and paranoia around 'nefarious intentions' in the US. Some US media pundits, fueled in this idea by a US Government Task Force and a Congressional Hearing, have tried to push the narrative that the KMS satellites are EMP devices. Something which others have characterized as "grossly overstated" (see this debunk on 38North and further comments by others here in this Newsweek article) as North Korea does not seem to have nuclear weapons that are powerfull enough to cause serious EMP effects.

It will be interesting to see whether TIP's will appear for the other North Korean satellite, KMS 3-2, which I currently forecast to reenter somewhere in September-October 2023.

[The text of this post has been repeatedly updated. Post last updated: 4 July 2023, 09:40 UTC]

Thursday, 22 June 2023

UPDATED: Ceci n'est pas une pipe... (French and US missile tests in the Atlantic in June)

click map to enlarge

They must love Magritte over at the French DoD, looking at the shape of the exclusion zones for a missile test published as Navigational Warnings HYDROLANT 1371/23 and HYDROLANT 1372/23.

The Navigational Warnings point to a French missile test launched from DGA Essais de Missiles near Biscarosse in Nouvelle-Aquitaine, over the Bay of Biscaye, in the period 26 to 30 June 2023. Below is the text of the Navigational Warnings:

201628Z JUN 23
HYDROLANT 1371/23(36,37).
DNC 08, DNC 19.
   46-33.50N 004-51.90W, 48-27.00N 010-03.00W,
   48-27.00N 015-12.00W, 47-04.50N 014-59.10W,
   46-05.70N 013-39.00W, 44-02.30N 001-20.00W,
   44-49.50N 001-12.30W.
2. CANCEL THIS MSG 302330Z JUN 23.

201646Z JUN 23
HYDROLANT 1372/23(36).
DNC 19.
   50-15.00N 011-08.00W, 49-40.00N 010-11.00W,
   48-27.00N 010-03.00W, 48-27.00N 015-12.00W,
   49-51.00N 013-15.00W.
2. CANCEL THIS MSG 302330Z JUN 23.


The shape and range of the Navigational Warnings suggest something SRBM/MRBM rather than, for example an SLBM. The curved shape is odd. After I posted the Warnings on Twitter, there has been some speculation that this might be a test of a hypersonic glider, perhaps V-Max. Taking into account the curve in the exclusion area, the range of this test would be in the order of 1250 km.


UPDATE 27 June 2023:

The test launch took place yesterday, 26 June 2023 at 22h CEST: see this French DoD bulletin, which also confirms that it was a test of the VMax glider on top of a sounding rocket.

A lot of chance sightings of the lingering missile exhaust cloud, illuminated by the sun, have been posted on Twitter, most of these from northern Spain but also a few from SW France. See for example here, here and here for a few examples. 

The French Ministère des Armées provided this image of  *a* launch. I have some doubts whether it is this particular VMAX launch, as the scenery seems sunlit with the sun in the South-Southeast (look at the shadows), while the launch was near 22 CEST, with the sun setting or just set in the Northwest...

[EDIT: the image seems to be a cgi render, i.e. not a real image, so that explains...]

Click to enlarge (image: Ministère des Armées, France)
[end of update]


More Atlantic tests: US or UK Trident test

This is not the only test in the Atlantic this June. Slightly earlier, a Navigational Warning, HYDROLANT 1302/23, appeared, strongly suggesting a Trident-II D5 SLBM test in the period 14 to 17 June 2023, launched from a submarine near Florida:

121246Z JUN 23
DNC 01, DNC 16.
   A. 28-39.00N 076-31.00W, 29-09.00N 076-13.00W,
      28-47.00N 074-59.00W, 28-17.00N 075-14.00W.
   B. 28-01.00N 073-25.00W, 28-07.00N 073-22.00W,
      27-53.00N 072-04.00W, 27-31.00N 071-57.00W,
      27-33.00N 072-24.00W.
   C. 25-46.00N 067-21.00W, 26-19.00N 067-01.00W,
      25-40.00N 065-42.00W, 25-08.00N 065-59.00W.
   D. 14-00.00N 042-36.00W, 14-14.00N 042-28.00W,
      13-41.00N 041-24.00W, 12-15.00N 039-09.00W,
      11-40.00N 039-30.00W, 12-41.00N 041-09.00W.
   E. 19-32.00S 007-27.00E, 18-42.00S 007-53.00E,
      19-52.00S 010-33.00E, 20-46.00S 010-02.00E,
      20-24.00S 009-17.00E, 20-12.00S 008-49.00E,
      20-06.00S 008-41.00E, 20-03.00S 008-33.00E,
      20-02.00S 008-29.00E.
2. CANCEL THIS MSG 170129Z JUN 23.

Here is the map I created from this Navigational Warning, with the areas A to E and the approximately 10600 km trajectory:

click map to enlarge

At the moment of writing, we are past the window of the Navigational Warning for this Trident test, but no word has come about a successful test launch yet.

The launch area some 450 km out of the coast of Florida is one of two regularly used launch areas for Trident test launches. It is launch area 2 in the compilation below of data from nine 9 Trident test launches from the last 10 years I could identify:

click map to enlarge

The RV target area in front of the coast of Namibia is near one of three areas regularly used (target area 3 in the map below), but somewhat closer to the African coast than previous tests:

Click map to enlarge    

A few more maps for tis and histroic Trident tests: first, stage 1 and stage 2 splashdown areas for launches from launch area 1 (top) and launch area 2 (bottom):

Launch area 1 launches. Click map to enlarge

Launch area 2 launche. Click map to enlarge

As I indicated in an earlier analysis, I suspect that launch area 1, much closer to the Florida coast than launch area 2, is used for launches with a VIP audience.

The two maps below show the mid-Atlantic third stage splashdown zones for the two launch areas in question:

Monday, 29 May 2023

UPDATED : North Korea announces satellite launch for May 30 - June 10

UPDATED 29 May 2023 12:00 UTC to reflect alternative orbit option

UPDATED 30 May 7:45 UTC to add comparison with 2016 launch 

UPDATE 30 May 22:00 UTC: the launch seems to have happened, around 21:30 UTC (May 30)

UPDATE 31 May: the launch reportedly failed early in flight due to a problem with the 2nd stage

(this post has been updated several times, with new pargraphs added, following development of the case. Newest paragraphs are near the bottom of the post)

According to South Korean media
, North Korea has informed Japan that they will launch a satellite between May 31 and June 11. Navigational Warnings have appeared that suggest a launch in this period as well.

Navigational Warning HYDROPAC 1779/23 (see below) gives three hazard zones, the first two of which line up with the Korean launch site Sohae. Below is the text of the Navigational Warning in question, and a map where I have plotted the three hazard zones A, B and C and the approximate launch trajectory I reconstruct from these (numbers next to the trajectory indicate minutes after launch):
[UPDATE: but see alternative option near bottom of post, that I am increasingly inclined to]

click map to enlarge

282008Z MAY 23
HYDROPAC 1779/23(91,92,94).
DNC 11, DNC 23.
   301500Z MAY TO 101500Z JUN
   A. 36-06.56N 123-33.07E, 35-24.31N 123-22.47E,
      35-20.01N 123-48.37E, 36-02.26N 123-59.11E.
   B. 34-05.54N 123-01.59E, 33-23.28N 122-51.53E,
      33-16.32N 123-29.40E, 33-58.58N 123-40.04E.
   C. 14-54.10N 128-40.06E, 11-19.18N 129-10.50E,
      11-26.49N 129-54.08E, 15-01.42N 129-24.03E.
2. CANCEL THIS MSG 101600Z JUN 23.

Note that May 30, 15:00 UTC corresponds to May 31, 00:00 local date/time in North korea, and June 10, 15:00 UTC to June 11, 00:00 local date/time. So the window of the Navigational Warning, in local North Korean date/time, matches that given by North Korea.

click map to enlarge

Areas A and B between China and Korea are likely the splashdown zones for the first stage and fairings, area C east of the Philippines is the splash-down zone for the second stage. Their relative locations point to a dog-leg manoeuver just after launch, after first stage separation and fairing ejection. First stage and fairing continue on the original launch course untill splashdown, the second and third stage, after the dogleg, insert the payload into a ~78 degree (give or take a degree or two)  inclined orbit.

The orbit is NOT sun-synchronous. It is different in orbital inclination than the orbits of the previous North Korean satellite launches: KMS (Kwangmyŏngsŏng) 3-2 and KMS 4, which are in 97.2-97.3 degree inclined orbits.

UPDATE (29 May 2023 12:00 UTC)

It was deep into the night when I originally wrote this blogpost. After a night's sleep and a discussion with Bob Christy, I am inclined towards another solution: direct insertion into a 97.2 degree inclined sun-synchronous orbit, followed by an avoidance manoeuvre of the 2nd stage after 3rd stage separation to avoid the 2nd stage falling on the Philippines:

click map to enlarge

click  map to enlarge

The location of areas A and B would fit well with this scenario. The risky part is that it means an overflight of the coastal PRC and Taiwan early in the launch trajectory. If something goes awry, this could result in hardware coming down on the PRC, Taiwan of Philippines nevertheless.

Yet this option is more and more enticing to me. The resulting orbit would be sun-synchronous, i.e. fitting an optical reconnaissance satellite, and similar to the orbits of KMS 3-2 and KMS 4. The scenario to arrive there however differs from the 2012 and 2016 launches. Here initial launch direction is into the intended orbital plane and the 2nd stage is doing a post-separation avoidance manoeuvre; whereas in 2012 and 2016, the initial launch direction was different and the 3rd stage did a manoeuver and pushed the payloads into the final orbit. The post-separation avoidance manoeuver of the 2nd stage in the current scenario would point to a (new) re-startable 2nd stage, which is interesting

The 2nd stage will splash down into a very deep part (5.7 km) of the Pacific Ocean, which makes recovery very challenging. This could be another reason why they divert it into this direction. It could be an indication that the 2nd stage is something new that they don't want to fall into the wrong hands.

If the launch is done at similar solar elevations as in 2012 and 2016, we can expect launch near 21:50-21:55 UTC, about 1.5 hours after sunrise at Sohae.

The intended orbital altitude is probably near 500 km.

Below is a very rough orbit estimate for launch at 21:50 UTC on the first available date (May 31 6:00 local time in N Korea is May 30 in UTC):

KMS 5                          for launch on 30 May 2023 21:50:00 UTC
1 70000U 23999A   23150.90972222  .00000000  00000-0  00000-0 0    06
2 70000 097.2299 155.8806 0003636 152.0900 325.4205 15.22766913    08

UPDATE (30 May 22:00 UTC):

Launch seems to have been near 21:30 UTC. here is an orbit estimate, assuming direct insertion into SSO, for launch at 21:30 UTC:

KMS 5                          for launch on 30 May 2023 21:30:00 UTC
1 70001U 23999A   23150.89583333  .00000000  00000-0  00000-0 0    06
2 70001 097.2299 150.8669 0003636 152.0900 325.4205 15.22766913    01

UPDATE 30 May 2023, 7:45 UTC:

In the map below I have depicted the location of the hazard zones and (initial) launch directions for the launch of KMS-4 in 2016 (blue), and the upcoming launch (red). Note the difference in (initial) launch direction between 2016 and now, and the odd off-set chacater of area C for the current launch:

click map to enlarge


In 2016, it was the third stage that did a dog-leg to get the payload into a 97.2 deg inclined Sun-synchronous orbit. The initial launch trajectory was probably selected to minimize risk of the 1st stage falling on the PRC and the second stage falling on the Philippines:

click map to enlarge

It is very clear that the upocoming launch will be according to a different scenario than the 2016 KMS-4 launch. Something odd is happening with the second stage, clearly.



The launch failed in flight, according to the North Korean State News Agency KCNA due to a problem with the 2nd stage. The KCNA news  report provides a launch time of 6:27 North Korean time (21:27 UTC May 30). It mentions that the launch was with a new type of carrier rocket, "Chollima-1", and gives the name of the failed satellite as "Malligyong-1".

It says that the failure was due to "losing thrust due to the abnormal starting of the second-stage engine after the separation of the first stage during the normal flight".

Yonhap reports the crash site as "200 km west" of the island of Eocheongdo. That matches well with area A, the first stage splash-down zone, from the Navigational Warnings (see map below). If the second stage failed to ignite, both the first stage and the second/third stage plus payload stack could have ended up here.

One of the stages has been recovered by South Korea, presumably from this area (photo's in this tweet thread). It seems quite intact and could be the spent first stage.

click map to enlarge

North Korea recently released images of the payload during factory testing, and already hinted at a nearby launch (see previous post here).


image: KCNA

Wednesday, 17 May 2023

Gearing up for a new North Korean satellite launch

photo: KCNA

On May 17, the North Korean News Agency KCNA and the North Korean State Newspaper Rodong Sinmun carried a news item, accompanied by photographs, of Kim Jung Un and his daughter Kim Ju Ae inspecting a new North Korean satellite in its assembly facility.

Photographs show a satellite purportedly undergoing testing. It is identified in the news items as military reconnaissance satellite no. 1, said to be "at the final stage" and "ready for loading after undergoing the final general assembly check and space environment test".

The satellite looks superficially similar to Kwangmyŏngsŏng-3 (KMS-3).  It is an oblong box with what looks to be hinged, deployable solar panels on two of its four sides. 

The satellite has been blurred on the imagery. What appears to be sensors can nevertheless be seen, albeit blurred (and perhaps the images might be in other ways manipulated).

My cautious estimate is that the satellite measures approximately 1.5 x 1.2 x 0.6 meter.

photo: KCNA

photo: KCNA

photo: KCNA

Protrusions that could be sensors can be seen, on the top and on the sides. Here are some very cautious interpretations (and I am open to other suggestions) of the blurred imagery details:

possible sensors on top (interpretation)

possible sensors on side (interpretation)

The most likely launch site will be Sohae (39.66N, 124.70 E), where previously KMS 3-2 and KMS 4 were launched from. Sohae has seen intermittent construction works the past year.

In April, North Korean State Media already announced that the country was at the verge of a reconnaissance satellite launch. Components purportedly have been tested as part of recent missile test launches, some of which featured remote sensing imagery.

This new KCNA report of Kim Jung Un visiting the test/assembly facility, is another sign that a satellite launch is probably not too far off in the future.

Most likely the satellite will be launched into a ~97 degree inclined sun-synchronous polar orbit at roughly 500 km altitude, as KMS 3-2 and KMS 4 were. KMS 3-2 and KMS 4 were launched with UNHA-3 rockets: perhaps this new satellite will be as well.

The imagery below, which I shot in September 2018, shows North Korea's satellite KMS-4 (Kwangmyŏngsŏng-4), which was launched in February 2016 and was their last satellite launch:

Sunday, 7 May 2023

Calibrating tracking astrometry accuracies using SWARM as calibration objects

Artist impression of SWARM (image: ESA)


When I started tracking satellites and publishing this blog 18 years ago, I spent a lot of time on validating the accuracy of my methods and observations. A lot has happened since then: I moved on to better equipment, and new validation methods have become available.

In this blogpost, I revisit the accuracy of my current video observations, using ESA's SWARM satellites as calibration targets.

The SWARM satellites (2013-067A, B and C) are well suited for system validation. Accurate GNSS-fit based orbital positions with centimeter accuracy are publicly available for these satellites, which means there is a firm reference to compare to. And the SWARM satellites are quite bright, hence they are relatively easy to observe (the video below shows a pass of SWARM A on 27 March 2023, imaged with a 85 mm lens).




Observations, equipment and methods

From the last week of March 2023 to the 3rd week of April 2023, I targetted SWARM A and B while they were making a series of well-observable passes over Leiden. 

There were two reasons for this endeavour. One was the creation of a good tracking dataset with known 'ground truth" for our research at Delft Technical University, where a colleague is working on improved methods of orbit determination from optical observations. The second was, that such observations provide you with information on the astrometric accuracy of various camera/lens combinations. 

My previous endeavours to gain insight into the accuracy of my observational data were based on comparisons of observations to TLE's. True vector positions from fitting to data from GNSS receivers onboard the satellite(s) are however much more suited for this than TLE's, as they are much more accurate (to cm-level, whereas those of a TLE are to km level).

The equipment I used to obtain the data presented in this blogpost was a WATEC 902H2 Supreme camera with a GPSBOXSPRITE-2 GPS time inserter, and three lenses: a Pentax 1.2/50 mm, a Samyang 1.4/85 mm and a Samyang 2.0/135 mm. Astrometry on the imagery was done on a frame-by-frame basis using Hristo Pavlov's TANGRA software.

WATEC 902H2 Supreme camera with Pentax 1.2/50 mm lens and GPS time inserter

same camera as above but with 2.0/135 mm lens

The camera films at 25 frames/second. The PAL video signal is fed into the GPS time inserter, which imprints each frame with a millisecond-accuracy time marking. The signal is then fed into an EZcap digitizing dongle and recorded on a laptop, after which astrometry is done on the files with TANGRA, on a frame-by-frame basis.

Observations were done on 8 separate nights in the period 27 March-19 April 2023. 1544 datapoints from 3 separate passes were obtained with the 50 mm lens; another 4100 datapoints from 5 separate passes with the 85 mm lens; and 891 datapoints from 3 separate passes with the 135 mm lens.

In addition to this, Cees Bassa and Eelke Visser both provided a set of data from their video systems. This allowed to explore any differences between their equipment and mine.

Cees and Eelke use USB connected ZWO ASI camera's with a CMOS sensor. Cees' camera is a ZWO ASI 1600 MM with a 1.4/85 mm lens; and Eelke's camera is a ZWO ASI 174MM with a 1.4/50 mm lens. 

Their timings come from the PC clock which is synchronized through NTP. Their astrometry is done using Cees' STVID software. As we will see later, there are some clear differences in accuracy between their systems and my system.


Reference positions

I wrote a software program, "Vect2RADEC', that converts SWARM navigational positions (ITRF X Y Z coordinates) to J2000 RA and DEC positions as seen from the camera location, and optionally also calculates residuals with astrometrical positions if you provide a file with the latter. The software is available in the software section of my website at (64-bits Windows only).

Results (1)

First, results for my own system using various lenses. Below are error distribution plots for the three lenses used: plotted is the distribution of the distance delta (in arcseconds) between the astrometrically measured, and actual GNSS derived position.

The first plot is a combined plot, followed by plots per lens. The average accuracy, and the one sigma standard deviation on this, is listed in the plots as well.

combined plot of error distributions

For each lens, the average accuracy is clearly better than the one-pixel resolution of the camera/lens combo in question. These pixel resolutions are resp: 

1 pixel = 35.4"  for the 50 mm  lens; 

1 pixel = 20.9"  for the 85 mm lens;

1 pixel = 13.1"  for the 135 mm lens. 

The actual astrometric accuracies are at about 2/3rd of this, i.e. astrometric positions are accurate to sub-pixel level.

The error distribition for the 50 mm lens is a normal distribution. Those for the 85 mm and 135 mm lens are increasingly skewed, showing a tail towards lower accuracies in their error distributions.

The tails to lower accuracy in the plots for the 85 mm and 135 mm lens are caused by trailing of the satellite in individual frames: at the resolutions of these lenses, trailing becomes apparent at shorter range to the camera. TANGRA does not center well on trails, the software is meant to fit on point-like objects.

The dependency of accuracy on range for the various lenses as a result of trailing  is visible in these plots of error against range:


At the resolution of the 50 mm lens, trailing is not much of an an issue, even at minimum range: the error is constant. With the 85 mm lens, trailing (with a corresponding drop in accuracy) starts once the range is less than ~725 km. With the 135 mm lens, it starts as soon as the range is less than ~1200 km.

The following diagrams show the corresponding trends in actual error in meters at satellite range (perpendicular to the viewing direction), for the three lenses:

Results (2)

As a second investigation, it was interesting to compare the performance of my system to that used by Cees Bassa and Eelke Visser, who graciously made data available to me for this purpose. 

In the diagram below, the distribution of residuals from Cees' system (green) is compared to those for my system (blue) for the same lens, a 1.4/85 mm Samyang lens.  Cees' data (with a much lower number of individual datapoints) have been scaled on the Y-axis to visually match mine, in order to make the visual comparison of both distributions more easy.

What is immediately apparent is the difference in accuracy. The average error in Cees' results in a factor 6 worse than mine, and the distribution spreads much wider as well. It is also a factor 5 worse than the pixel resolution of his camera (whereas mine is at 2/3rd of the pixel resolution). Eelke's data, not visualized here, show a similar pattern.

The software which I wrote to assess these errors, currently does not differentiate between along-track ("delta T") and cross-track errors. A comparison of Cees' and my data against a TLE using Scott Campbell's SatFit software, which does differentiate between delta T and cross-track error (but only to two decimals behind the dot, in degrees and time), suggests that much of the difference in error actually stems from a larger along-track error, i.e. an error in the timing, in Cees' data.

This could have a couple of causes. One or more of these factors could be in play here:

(1) an uncorrected latency introduced by Cees' camera system;

(2) a latency introduced by the pc clock-to-STVID throughput of times

(3) a residual latency in the NTP time source

(4) the frame exposure mid-time registered by STVID might actually be the start- or end-time of the frames

(5) the frame stacking method used by STVID

NOTE: It should be explicitly remarked here that Cees never designed his system and software with the kind of precise accuracies in mind that we are mapping here

In our independent tracking network focussing on orbit determination of classified objects, we generally are happy if positions reported are accurate to 2 arcminutes, rather than a few arcseconds. This is because of two reasons:

(a) The goal is to create TLE's for orbit characterization and overflight predictions for these objects. TLE's have an intrinsic accuracy of 1 km (and worse away from epoch time) in position, so a 2 arcminute accuracy in positional determinations is sufficient for this goal.

(b) Positional data of varying quality obtained by various different methods are lumped in the orbit determinations by our independent network analysts. These include: visual observations with binoculars and stopwatch; camera still images; video data with astrometry on either stacked frames or individual frames; with timing sources varying from stopwatch synchronization to radio "six pips", DCF77 radio-controlled clocks, to software synchronization to NTP time synchronization, to GPS time inserters. 


NOTE ADDED 9 and 10 May 2023:

In a discussion on Twitter, the issue of light travel time was raised. I have come to the conclusion that this is almost certainly already included in the AFSPC-origin libraries I use for my software (even though not explicitly documented for the conversion of ECI position to RA/DEC as seen from the station, it is documented for another conversion, so likely to be incorporated in the former as well), for as I try to include my own additional correction, this actually makes the residuals worse.


Acknowledgement: I thank Cees Bassa and Eelke Visser for providing comparison data from their systems.