The Chinese space plane test of 16 July 2021: orbital, not suborbital?

click map to enlarge

 

In my previous post I debated at length a claim by the Financial Times on October 16 that China recently did a FOBS test. This claim seems to be currently disintegrating, as suspicion is rising (following rebuttal comments by a Chinese Government offcial) that it all seems to refer to a Chinese reusable Space Plane test flight on July 16 instead. A test flight which was already reported earlier and hence known.

At the time when that Chinese Space Plane test flight was reported in July, it was reported as having been suborbital. This was (I think) mostly based on the proximity of the reported launch site (Jiuquan) and landing site (Badanjilin Airport), which are only some 220 km apart (indicating a short suborbital "hop").

But I now think that judgement was in error. 

If the whole FOBS-story indeed actually refers to the July 16 test flight, then it seems that it was orbital, completing one revolution.

Indeed, upon looking into it and trying some orbital scenario's, I found that a launch from Jiuquan into a 41.07 degree inclined orbit would actually very well match with a landing at Badajilin Airport at the end of one full revolution. I have depicted the resulting trajectory in the map in top of this post.

So: FOBS or space plane? Jeffrey Lewis has a point when he tweets:

"China just used a rocket to put a space plane in orbit and the space plane glided back to earth. Orbital bombardment is the same concept, except you put a nuclear weapon on the glider and don’t bother with a landing gear." - Jeffrey Lewis

But then, Mark Gubrud is likely also right about design differences when he tweets that:

"A FOBS/hypersonic missile would be optimized differently from a space plane. The plane would be designed to slow as much as possible on reentry (hence the blunt design of the Shuttle). It would have landing gear. It would have a payload bay, instead of an integral warhead."

The trajectory of the July 16 space plane flight, if my interpretation is correct, is not very FOBS-like. But this was only a test flight. Jeffrey is right that a space plane or glider in principle is suited for a deorbit with something in it's cargo bay that can go BOOM. This is why some other nations look with suspicion at the US X-37B space plane, currently on its sixth mission.

About the airport at Badanjilin: it seems to have been constructed rather recently. It is not present in Google Earth imagery from as recent as 2016. The landing strip is some 2.4 km long, oriented northwest-southeast, azimuth 313-133 degrees, and located at 39.2264 N, 101.5477 E. Below is a Copernicus Sentinel 2A image of the airport taken on 31 July 2021 (note the Camel!):

click image to enlarge

UPDATE 18 Oct 2021 19:45 UT:

Something very confusing is that, while the Chinese Government now seems to suggest that the orbital flight reported on by the Financial Times in fact was this July 16 space plane flight, Chinese news items on this space plane flight from that time seem to state that the flight was "suborbital", as Jonathan McDowell has pointed out. 

Still, I am not convinced as the word is used several times in a context where it is odd (e.g. when describing the space plane as a technology). The same in an English language bulletin by Xinhua, which also talks about a "reusable suborbital carrier". That sounds more like an aircraft to me (perhaps one launched with a booster stage and then flying through the upper atmosphere), than a space plane. I have no knowledge of the Chinese language at all (the only thing I can say in Chinese is "thank you") so do not know what is possibly lost in translation here.

Even more confusingly, the first Chinese item linked above seems to name yet another airport (so another one than that pictured above) as the landing site:  Youqi airport. I found a Youqi airport which is near 48.5764 N, 116.9377 E. The runway of that airport however seems a bit short for a space plane landing. Jonathan McDowell  thinks I got the wrong Youqi and points out that the Badanjilin Airport imaged above is also called Youqi....oh well. He probably is right (he usually is). We can use some more confusion in this already confusing case...

Both with regard to "FOBS or not", and the July 16 "space plane", many things remain very ambiguous.

It could be that the Chinese Government is now seizing on the July 16 test to explain away a later FOBS test.

A Chinese FOBS surprise (and other stuff of nightmares) [UPDATED]

 

[this post was updated on October 18 to reflect new information and a refutal of the claim by the Chinese Government. It was again updated on October 21 to reflect new information, including claims that it concerned *two* tests, on July 27 and August 13]

If you want to have nightmares for days, then listen to Jeffrey Lewis menacingly whispering "fòòòòòòòòòòbs..." in the first few seconds of this October 7 episode of the Arms Control Wonk Podcast...

I bet some people connected to US Missile Defense hear this whisper in their sleep currently, given news that broke yesterday about an alledged Chinese FOBS test in August.

FOBS (Fractional Orbital Bombardment System) has menacingly been lurking in the background for a while. In the earlier mentioned podcast it was brought up in the context of discussing new pictures from North Korea showing various missile systems: including a new one which looks like a hypersonic glide vehicle on top of an ICBM (which is not FOBS, but FOBS was brought up later in the podcasts as another potential future exotic goal for the North Korean missile test program).

image: Rodong Sinmun/KCNA

But the days of FOBS being something exclusively lurking as a menace in the overstressed minds of Arms Control Wonks like Jeffrey are over: the whole of Missile Twitter is currently abuzz about it.

The reason? Yesterday (16 Oct 2021) the Financial Times dropped a bombshell in an article, based on undisclosed intelligence sources, that claims China did a test in August with a system that, given the description, seems to combine FOBS with a hypersonic glide vehicle. [edit: but see update at end of this post]

That last element is still odd to me, and to be honest I wonder whether things have gotten mixed up here: e.g., a mix-up with a reported Chinese suborbital test flight of an experimental space plane from Jiuquan on 16 July this year. [edit: and this might be right, see update at the end of this post]

Anyhow: the FT claims that China:

"tested a nuclear-capable hypersonic missile in August that circled the globe before speeding towards its target".

"Circled the globe" before reaching it's target: that is FOBS.

 

FOBS

So, for those still in the dark: what is FOBS?

FOBS stands for Fractional Orbital Bombardment System. Unlike an ICBM, which is launched on a ballistic trajectory on the principle of "what goes up must come down", FOBS actually brings a nuclear payload in orbit around the earth, like a satellite.  

For example, a very Low Earth Orbit at an orbital altitude of 150 km, which is enough to last a few revolutions around the earth. At some point in this orbit, a retrorocket is fired that causes the warhead to deorbit, and hit a target on earth.

FOBS was developed as an alternative to ICBM's by the Soviet Union in the late 1960-ies, as a ways to evade the growing US Early Warning radar system over the Arctic. Soviet ICBM's would be fired over the Arctic and picked up by these radar systems (triggering countermeasures even before the warheads hit target). But FOBS allowed the Soviet Union to evade this by attacking from unforseen directions: for example by a trajectory over the Antarctic, which would mean approaching the US from the south, totally evading the Early Warning radars deployed in the Arctic region.

In addition, because FOBS flies a low orbital trajectory (say at 150 km altitude), whereas ICBM's fly a ballistic trajectory with a much higher apogee (typically 1200 km), even when a conventional trajectory over the North Pole would be used, the US radars would pick up the FOBS relatively late, drastically lowering warning times (the actual flight times of an ICBM and a FOBS over a northern Arctic trajectory are not much different: ~30 minutes. Over the Antarctic takes FOBS over an hour. But of relevance here is when the missiles would be picked up by US warning radars).

The Soviet Union fielded operational FOBS during the 1970-ies, but eventually abandoned them because new western Early Warning systems made them obsolete. This notably concerned the construction of an Early Warning system in space, consisting of satellites that continuously scan the globe for the heat signatures of missile launches. DSP (Defense Support Program) was the first of such systems: the current incarnation is a follow-up system called SBIRS (Space-Based Infra-Red System). This eliminated the surprise attack angle of FOBS, because their launches would instantly be detected..

 

Reenter FOBS

But now China has revived the idea, moreover with an alledged test of an actual new FOBS system (while Russia also has indicated they are looking into FOBS again). From the description in the Financial Times, which is based on undisclosed intelligence sources, the Chinese FOBS system moreover includes a hypersonic gliding phase. [edit: but see update at the end of this post]

Initially this surprised me: I was of the opinion (and quarrelled with Jeffrey Lewis about this, but am man enough to now admit I was wrong and he was right. Sorry Jeffrey, I bow in deep reverance...)  that FOBS in 2021 had very little over regular ICBM technology and was therefore a very unlikely strategy, feasible only as a desperate last defensive act of revenge before total annihilation in case of an attack by others. Because using FOBS in an offensive tactical role would guarantee you to lead to Mutually Assured Destruction.

I still stand behind that last part, but clearly, China thinks they nevertheless need FOBS. Why?

FOBS still has one advantage over regular ICBM's. That is, that a southern trajectory over Antarctica approaching the US mainland from the south, while not going undetected by SBIRS, still avoids warhead intercepts by the US anti-Ballistic Missile Defense (BMD) systems, that are currently geared to intercept a regular ICBM-attack over the Arctic or from the west (North Korea).

I should ad here: "for the time being".... The logical answer by the US (unless they chose to continue to ignore China with regard to BMD, as they did untill now) will now be to extend their BMD coverage to the south. For countering FOBS, they could use the same AEGIS SM-3 technology that they used to down the USA 193 satellite in 2008 (Operation Burnt Frost).

Here are two maps I made, one for a FOBS attack on Washington DC from China and one for a FOBS attack on Washington DC from North Korea. The red lines are ballistic ICBM trajectories (over the Arctic), and current BMD sites are meant to intercept these kind of trajectories. The yellow lines are FOBS trajectories over the Antarctic, showing how these attack the USA "in the back" of their missile defenses by coming from the south instead.

hypothetical FOBS attach from China. Click maps to enlarge

 

hypothetical FOBS attack from North Korea. Click map to enlarge

As the USA is currently putting much effort in Ballistic Missile Defense, developing a new FOBS capacity could be a way by which China is warning the USA that even with BMD, they are still vulnerable: i.e. that they shouldn't attempt a nuclear attack on China from a notion that their BMD systems make them invulnerable to a Chinese answer to such an attack. 

FOBS is hence a way of creating and utilizing weaknesses in the current BMD capacity of the USA, as a counter capacity.

It should be remarked here that the US BMD capacity is geared towards missiles fired by Russia or by  'Rogue Nations' like North Korea and Iran. The USA seems to have largely ignored China so far with regard to BMD. Meanwhile, China is concerned with the US BMD development, particularly deployment of BMD elements in their immediate region.

So this FOBS experiment could also be a way in which China tries to force the US to finally take the Chinese concerns about US BMD deployments and the inclusion of their region into such deployments, serious. 

 

Outer Space Treaty

China (like the US and Russia) is a signatory of the Outer Space Treaty (or, in full: the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies). 

FOBS seems to be a violation of this treaty, as Article IV of the treaty clearly states that:

 "States Parties to the Treaty undertake not to place in orbit around the earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction"

This is exactly what FOBS does: it (temporarily) places a nuclear weapon in orbit around earth, so that they can later bring it down over a target.

The Soviet Union, when testing FOBS in the late '60-ies, tried to get out from under this by claiming that, as their FOBS did not complete a full orbit around the Earth, article IV of the treaty didn't apply. The US Government, surprisingly -and for opportunistic reasons- went along with this interpretation (see this article in The Space Review). Which is, pardon me the word, of course bullshit: in the sense of orbital mechanics (that is to say; physics), FOBS clearly does place an object in orbit, and it is very clear too by the fact that after launch it needs an actual, separate deorbit burn to get it down on the target.

 

North Korea and FOBS

How about North Korea? As I mentioned, FOBS has been repeatedly mentioned as a potential route North Korea might take with its nuclear missile program. Some fear that NK could be developing a FOBS capacity in order to have a means of final-revenge-from-over-the-grave from the Kim Jong Un regime in case of a 'decapitation' attempt (an attempt to end the Kim Jong Un regime by a targetted military strike on KJU and  his family members).

One reason behind this fear is that North Korean Kwangmyŏngsŏng (KMS) satellite launches were on a trajectory over Antarctica, bringing the payload over the US only half a revolution after the launch.

Compare this launch trajectory of KMS 3-2 in December 2012 for example (which comes from this 2012 blog post), to the hypothetical FOBS trajectory in the map below it: the similarities are obvious (if perhaps superficial).

KMS satellite launch trajectory (above) and hypothetical FOBS attack from North Korea (below). Click map to enlarge

It wouldn't surprise me if FOBS will quickly replace the EMP 'threath' that over the past decade has been hyped by certain hawkish circles in the US defense world, as the horror-scenario-en-vogue.

 

Something worse than FOBS? DSBS!

So, can we think of something even more sinister than FOBS? Yes, yes we can, even though so far it is completely fictional and a bit out there (pun intended).

Let us call this very hypothetical menace DSBS. It is truely something out of your nightmares.

DSBS is a name I coined myself for a so far nameless concept: it stands for Deep Space Bombardment System. DSBS at this point is purely fictional, with no evidence that any nation is actively working on it: but the concept nevertheless popped up, as a distant worry, in a recent small international meeting of which I was part (as the meeting was under Chatham House rules, I am not allowed to name participants). So I am not entirely making this up myself (I only made up the name to go with this so far unnamed concept).

The idea of DSBS is that you park and hide a nuclear payload in Deep Space, well beyond the Earth-Moon system: for example in one of the Earth's Lagrange points. There you let it lurk, unseen (because it is too far away for detection). When Geopolitical shit hits the fan, all is lost and the moment is there, you let your DSBS payload return to earth, and impact on its target.

With the current lack of any military Xspace (Deep Space) survey capacity,  such an attack could go largely undetected untill very shortly before impact. Your best hope would be that some Near Earth Asteroid survey picks it up, but even then, warning times will be short. Moreover, with the kind of impact velocities involved (12+ km/s), no existing Ballistic Missile Defense system likely is a match for these objects.

Far-fetched? Yes. But that is also something once said about FOBS...

(Note: I hereby claim all movie rights incorporating DSBS scenario's)

(added note: I only now realized, when answering a comment to this blogpost below, that, unlike FOBS or placing something in GEO, a DSBS parked in one of the Lagrange points would NOT violate Article IV of the Outer Space Treaty, because the device would NOT be in orbit around Earth (but co-orbital with Earth).

 

UPDATE 18 Oct 2021 10:45 UT and 20:10 UT: 

NOT FOBS?

China denies that they did a FOBS test: "this was a routine test of a space vehicle to verify technology of spacecraft's reusability", says a Chinese government spokesman. They reportedly also say the test happened in July, not August. That could mean that this earlier reported test flight of a prototype space plane on July 16 was concerned (a suspicion I already voiced earlier in this blogpost and at the Seesat-L list). 

Of course, as Jeffrey Lewis rightfully remarks, spaceplane technology shares a lot with FOBS technology. In Jeffrey's words:  "China just used a rocket to put a space plane in orbit and the space plane glided back to earth. Orbital bombardment is the same concept, except you put a nuclear weapon on the glider and don’t bother with a landing gear."

At the time, this space plane test was interpreted to have been suborbital, as the space plane reportedly landed in Alxa League, 800 km Badanjilin Airport, 220 km from the launch site, Jiuquan. I today however realised that this might have been a misinterpretation: it might actually have been an orbital, not suborbital, test fligth landing at the end of the first revolution. 

Indeed, I managed to create a hypothetical 41.2 degree inclined proxy orbit for a  launch from Jiuquan that brings it over Alxa League Badajilin Airport at the end of the first revolution.

Slightly more on this in this follow-up blogpost. which also points out that a Chinese source confusingly points to yet another airport as the landing site of the July 16 space plane test (if it was a space plane at all and not some upper atmospheric aircraft vehicle).

It could be that the Chinese Government is now seizing on the July 16 test to explain away a later FOBS test.

click map to enlarge

 UPDATE 21 October 2021 10:25 UT:

New information circulated by Demetri Sevastopulo, the FT journalist that broke the story, indicates that there were *two* tests, on July 27 and August 13. The first date tallies with rumours that reached me on July 29 about an 'unusual' Chinese test apparently having taken place (that I at the time erroneously though might refer to the July 16 'space plane' test).

Spectacular deorbit burn / fuel dump from the Landsat 9 Centaur upper stage observed

click to enlarge

 

Yesterday 27 September 2021 at 18:12 UT, Landsat 9 was launched from Vandenberg with a ULA Atlas V rocket. 

2h 58m after the launch, after 1.5 revolutions and while over the east coast of the United Kingdom, the Centaur upper stage performed its deorbit burn, lowering perigee such that half an orbit later it would reenter over a designated area in the Pacific Ocean at the end of the second revolution. Following the deorbit burn, there was a fuel blow-out.

click map to enlarge

The deorbit burn and fuel blowout happened within minutes of shadow exit over NW Europe. When the resulting exhaust and fuel clouds came into sunlight, they caused a bright spectacle in the sky that was widely seen around 21:12 UT (23:12 CEST) from a.o. the Netherlands, the UK, Belgium, France and Scandinavia.

The event was anticipated: already before the launch, Cees Bassa had noted that the time of the burn coincided with a pass over NW Europe and alerted observers on the Satobs list. I then put out additional alerts on a.o. Twitter, and as a result, many people observed it. 

In addition, there were hundreds of unexpecting casual eyewitnesses, who often had no clue as to what they were seeing. One of the Dutch "UFO"-reporting sites got over 150 reports of a "UFO" in the northern sky as a result.

As seen from my hometown Leiden in the Netherlands, shadow exit would occur low in the northern sky, in Ursa Major. I had put up my camera opposite the historic Leiden Observatory in the center of Leiden, hoping to capture it over the telescope domes.

As it happened, the actual sky trajectory was slightly more eastwards in the sky than we had anticipated based on a pre-launch TLE estimate (my estimate placed in in the tail of the Big Dipper, while in reality it was in the bowl of the Big Dipper). Just enough to place it outside the FOV of my camera (and initially behind a tree). 

So when it became visible and I realized it was off the predictions, I quickly grabbed the tripod and repositioned it. This made me photographically miss the first 20 seconds or so of the event. Over slightly more than 1 minute, I managed to shoot 50 images of the exhaust and fuel clouds descending over the roof of one of the Observatory's auxilliary buildings.

I was lucky with the clouds too. Fields of cumulus were drifting across the sky, and the relevant part of the sky had been clouded out only minutes before the observation (the clouds leaving the scene are visible in the photographs and time-lapse below).

The event was downright spectacular: two v-shaped, comet-like clouds, one very bright and one fainter (see images) with the tips upward, moving down in the sky among the stars of Ursa Major. The brighter, trailing one of the two clouds was easily visible, and of negative magnitude (mag -4 perhaps, as a rough estimate). It's shape changed over time, with a shell-like structure moving away from the tip. Very spectacular!

The fainter cloud is probably rocket engine exhaust from the brief deorbit burn. The brighter cloud is a cloud of fuel particles, resulting from the blow-out (depressurization) of the Centaur's fuel tanks after the burn (this is a.o. done to avoid fuel remnants exploding). Both clouds are illuminated by the sun, which is why they are visible.

Here are some of the 50 images I shot

click images to enlarge

In two consecutive of the 50 images, an object briefly becomes visible between the fuel and exhaust clouds (arrow): it is not clear what this exactly is, as one would not expect the Centaur itself in this position (rather, at the tip of the bright cloud).

click to enlarge

Below is a time-lapse movie I constructed from the 50 images. It is at 13 times the real speed: the series of images from which the movie was made spans slightly over 1 minute in time:

The event happened somewhere between ~550 and 685 km altitude, over the United Kingdom and North Sea. An exact altitude cannot be given at the moment: landsat 9 was delivered to a ~685 km orbit, but the rocket made additional manoeuvres, while releasing cubesats.

I have always wanted to see an event like this, and now finally have (my 51 degree North NW European location does not see this kind of events often). Still on my list: a real reentry.

(all the images shown here were made with a Canon EOS 80D camera and EF 2.0/35 mm lens, at 1-second exposure at ISO 2500).

Inspiration4 Crew Dragon over the old Leiden Observatory

click to enlarge

 

The image above, which I shot yesterday evening (16 September 2021) around 19:24 UT, shows the SpaceX Crew Dragon Inspiration 4 with astronauts Hayley Arceneaux, Christopher Sembroski, Sian Proctor and Jared Isaacman onboard, over one of the domes of the old Leiden Observatory. This observatory is located in the center of Leiden, the Netherlands, close to my home.

The photograph is a stack of 37 1-second images taken between 19:24:05 and 19:25:19 UT with a Canon EOS 80D and EF 2.5/50 mm lens (at 800 ISO). The dome is the dome of the 50-cm Zundermann telescope. The brightest "star" is Jupiter, and the second trail near the bottom of the image next to the dome is an aircraft.

Inspiration 4 is the first Crew Dragon mission that was not commissioned by NASA and does not go to the International Space Station. Instead it will orbit for 3 days at an altitude of 570 x 580 km. The orbital plane is inclined by 51.6 degrees and does match the ISS orbital plane, although not the ISS orbital altitude. It was chosen so that the launch could use existing emergency and abort facilities on the launch track. 

Inspiration4 (2021-084A) was launched from pad 39A at Cape Canaveral on 16 September 2021 at 00:02:56 UT. The launch coincided, with a difference of only a few minutes, with a pass of the ISS:

 

While I was photographing the pass (which was a low elevation pass in late twilight at 25 degrees maximum elevation) from a spot at the Witte Singel opposite the observatory, my video setup was running on an automated schedule from my loft window and captured the spacecraft as well (WATEC 902H2 Supreme camera with 1.4/35 mm lens at 25 fps):

An upcoming Trident-II D5 SLBM test in the Atlantic

click map to enlarge

A few days ago a Navigational Warning (NAVAREA IV 838/21, also issued as HYDROLANT 2336/21) appeared which points to an upcoming Trident-II D5 SLBM (Submarine-Launched Ballistic Missile) test from a US or Royal Navy SSBN on the Atlantic Eastern Missile Range between 12:30 UT on September 17, and 1:23 UT on Sept 20. The distance between the launch area and MIRV target area is about 9900 km.

This is the text of the Navigational Warning (the map in top of this post shows them mapped, along with a simple ballistic trajectory):

151459Z SEP 21
NAVAREA IV 838/21(11,24,26).
ATLANTIC OCEAN.
FLORIDA.
1. HAZARDOUS OPERATIONS 171230Z THRU 200123Z SEP
   IN AREAS BOUND BY:
   A. 28-56N 079-59W, 29-02N 079-53W,
      29-06N 079-37W, 28-59N 079-10W,
      28-37N 079-10W, 28-36N 079-35W,
      28-45N 079-56W.             
   B. 28-24N 076-44W, 28-42N 076-42W,
      28-21N 074-40W, 28-06N 074-44W.
   C. 27-27N 071-21W, 27-52N 071-15W,
      27-25N 068-46W, 26-54N 068-54W.
   D. 17-22N 044-54W, 18-33N 044-32W,
      16-54N 040-55W, 16-00N 041-23W.
   E. 09-00S 003-51W, 08-22S 003-22W,
      12-35S 002-40E, 13-05S 002-19E,
      11-56S 000-16E, 12-09S 000-16W,
      11-34S 000-20W.
2. CANCEL THIS MSG 200223Z SEP 21.

The launch area (area A) is one of two launch areas used for these kind of tests in the Atlantic (see an earlier post from 2019 analyzing several of these launches). It is the variant closest to the Florida coast, one which I suspect is used when the launch has an 'audience' of officials.

The area is close enough to the Florida coast that Florida east coast residents might see the launch, as has previously happened.

The target area is the regular target area in the southern Atlantic some 1000 km out of the coast of Angola.

Areas B, C and D are where the first, second and third stage splash down.

 

 

The location of the hazard areas does not match a simple ballistic trajectory well (such a trajectory is indicated by the line in the map in the top of this post), which might point to some mid-flight manoeuvering of the MIRV-bus.

The test launch is probably a DASO ("Demonstration and Shakedown Operation"), done to recertify the readiness of the submarine and its crew after major overhauls. One candidate submarine for this test launch is the Ohio-class SSBN USS Tennessee (SSBN 734) which reportedly completed a major overhaul at Kings Bay on July 1. [EDIT 18 sept 2021 15:45 UT: it actually was USS Wyoming, which fired two Trident missiles as part of the test]

 

UPDATE 18 Sep 2021 15:45 UT

The US Navy has announced that as part of DASO-31, the Ohio-class SSBN-742 USS Wyoming has fired two Trident missiles on September 17th.

image: US Navy/David Holmes

image US Navy/David Holmes

PAN (NEMESIS 1) is on the move again

Pan on August 8/9, 2021, imaged from Leiden. Click image to enlarge

Five years ago, in 2016, I wrote a long article in The Space Review titled "A NEMESIS in the sky: PAN, Mentor 4 and close encounters of the SIGINT kind". The primary subjects of that article were two SIGINT satellites: PAN (Nemesis 1) and Mentor 4.

In the article, I discussed what we had observed and deduced about PAN as amateur trackers, to what had been recently revealed about PAN by leaked documents from the Snowden files.

In the article I documented the frequent movements of PAN (2009-047A): for four years between its launch in September 2009 and mid 2013, PAN, very unusual for a geosynchronous satellite, was roving from location to location, each time being put close to a satellite for commercial satellite telephony.
For information on the "why" of that, and the larger context of it (a new kind of SIGINT information gathering), I refer to the earlier mentioned Space Review paper which goes into details.

Mid-2013, four years after launch, the frequent relocations stopped. For 8 years, the position of PAN remained stable in longitude near 47^o.7 E. It's roving days, snooping around and sniffing other satellites, were over. Until this year.  

Somewhere between 6 February and 7 May 2021, PAN started to move again, eastwards in longitude. Observed longitudes over the period May-August 2021 suggest a drift eastwards at about 0.025 deg/day. 

Assuming a stable drift, the move appears to have been initiated within a few days of 11 February, 2021.The last observation still showing PAN at 47.7 E was on 6 February 2021 (as it happens, our network did not observe it again untill early May 2021 when it had already moved eastwards by two degrees).

The diagram below (an updated version of one that appeared in my 2016 Space Review article) shows the positions in longitude that PAN has been taking up since its launch in 2006. Note the frequent relocations over the period 2009-2013, then the long stabilization at 47.7E, and the start of a new drift episode in 2021:

click diagram to enlarge

The question now is, what this drift since February means:

(1) Has it deliberately been brought into a drift state to move it to an eventual new position? 

(2) Has it reached end-of-life and been manoeuvered into a graveyard orbit?

A 'graveyard orbit' is usually an orbit that is located at least 235 km higher than a geosynchronous orbit. That does not appear to be the case here: if anything, the orbit seems to be a few km lower than it previously was. So it appears to be option (1).

It will be interesting to see whether PAN will stabilize its longitude at some point or not, and where that will be. Unfortunately, as it is drifting eastwards it is getting lower in my sky (currently, it is some 16 degrees above my local horizon), and there do not appear to be many other amateurs covering it currently.

It would be interesting to see whether radio observers can detect radio signals from PAN, which shortly after launch was emitting at frequencies similar to that of the "UFO" (UHF Follow On) constellation.

PAN on 2/3 June, 2021, imaged from Schiermonnikoog Island. Click to enlarge

An Asteroid for Alice

 

 

As long-time readers of this blog know, I have been active in searching for Near Earth Asteroids (discovering two: 2005 GG₈₁ and 2015 CA₄₀). As part of that search, I also discovered a number of new Main Belt asteroids. 

A batch of these, that where discovered by Krisztian Sárneczky and me with the 60-cm Schmidt of MPC 461 Piszkéstető in Hungary in the period 2012-2016, are now well observed enough that they are getting permanent numbers issued by the MPC. Which means that we have the opportunity to suggest names for these asteroids to the IAU.

The first name we proposed was accepted and published by the Work Group on Small Body Nomenclature (WGSBN) of the International Astronomical Union (IAU) last week. 

It is with much pleasure that I can announce that asteroid (551014) = 2012 UU₁₈₅ will henceforth be called:

 

(551014) Gorman

 

...after Dr Alice Gorman, a pioneer "Space Archaeologist" and senior Lecturer at Flinders University in Australia.

 

Dr Alice Gorman

 

Dr Alice Gorman is a pioneer in the field of Space Archaeology: the study of human material culture in space, and Space-Age related human material culture on earth (e.g. old launch or tracking sites). Some of you may know here from her book "Dr Space Junk vs the Universe" (if you don't know the book, I can warmly recommend it).

 The naming citation for the asteroid was published on 3 September 2021 in WSGBN-bulletin vol 1. nr 7 and reads:

(551014) Gorman = 2012 UU₁₈₅ 

Discovery: 2012-10-18 / K. Sárneczky, M. Langbroek * / Piszkéstető / 461 

Alice Gorman (b. 1964) is an Australian archaeologist and an expert in lithic analysis and Heritage management. She is one of the pioneers in the field of space archaeology, the study of human material culture in space and related material culture on Earth.

Asteroid (551014) Gorman was discovered on 18 October 2012 as a magnitude +19.2 object by Krisztian Sárneczky and me with the 60-cm Schmidt of MPC 461 Piszkéstető Observatory in the Matra mountains of Hungary. The animated GIF in the top of this post shows a 'blink' of a small part of the three discovery images (taken about 15 minutes apart). The asteroid can be seen as a faint moving dot in the center.

Our initial internal reference for the objects given on the night of discovery was object SaLa016. After submission to the MPC, it got the temporary designation 2012 UU₁₈₅. In June this year, it was issued the permanent number (551014).

(551014) Gorman is an approximately 2 km wide asteroid (H = 15.9) that moves in the asteroid belt between Mars and Jupiter. It is a Main Belt IIIb type asteroid with perigee at 2.97 AU and an orbital inclination of 14 degrees. It takes the asteroid 5.8 years to complete one orbit around the sun.

 

It makes me very happy to have been able to name this asteroid after Alice!

First positive observations of the LED beacon of the NAPA-2 6U cubesat

 

On June 30, 2021, a Falcon 9 launched several cubesats in a rideshare launch called Transporter-2. One of the payloads was a 6U cubesat called NAPA-2. 

This cubesat was built by the Dutch company ISISpace in Delft (the same company that built Brik-II) for the Royal Thai Air Force. It is an IMINT satellite, carrying two small Earth observation camera's. It is in a 97.5 degree inclined sun-synchronous 520 x 540 km orbit with passes around local midnight and noon.

This is the NAPA-2 cubesat after assembly (image courtesy of ISISpace): the 6U cubesat measures about 10 x 20 x 30 cm.

image (c) ISISpace, used with permission.

NAPA-2 has an interesting novelty: it carries a beacon of 12 bright LED's that can be switched on and off by the satellite operators. 

It is an experiment to see if such a bright artificial lightsource on the satellite can aid in optically tracking it.

The past few days saw the commissioning of this feature. ISISpace had asked me whether I could try to image the LED beacon from Leiden. Attempts to image it were made on three nights. 

The first attempt, on August 24 using a 1.4/85 mm lens, was negative.

The second attempt was on August 25. The operators had reorientated the satellite such that the LED's were pointing at the groundstation. This attempt was marginally positive: it was seen but the satellite was extremely faint and barely visible and the trail was lost in the noise background in a frame stack.

A third attempt was made last night, in the early hours of 27 August. This time I used a more powerfull lens, the Samyang 2.0/135 mm. The camera was a WATEC 902H2 Supreme operating at 25 frames/s.

The result was a positive detection: the LED beacon of the satellite, although faint, was unambiguously imaged. The range to the satellite was 598 km during the observation. It was imaged around culmination at 61 degrees altitude in the east.

 

click to enlarge

 

Below is the video: the object, coming into the FOV from the right, is very faint, but visible. It disappears near the center of the image because the LED was switched off: the operators operated it is a "3-seconds-on, 1-second-off" mode last night.

Below is a framestack of 60 frames from the video (2.4 seconds of footage). A faint but unmistakable trail can be seen entering the FOV from the right: the LED beacon of NAPA-2! The bright star near the bottom of the image is 13 Persei.

Below is a negative image version of the same stack: and a positive version where I pushed the image such that the trail comes out better.

 

 

It should be noted that the cubesat was imaged in a part of it's trejactory where it was in Earth shadow: so all the light solely comes from the 12 LED's!

This is the LED array on the satellite (image courtesy of ISISPace):

image (c) ISISpace, used with permission.

Amazing that 12 LED's are visible from a distance of almost 600 km! 

The LED beacon does not operate continuously: it is only briefly switched on when passing over a tracking station (in this case, my observing location). It reaches an Rmag of about +10.

Below are the astrometric residuals relative to CSpOC elset 21239.30175625 (angles are in degrees, delta T in seconds), showing the good match:

     STA   YYday HH:MM:SS.sss   AZ     EL     XTRK     deltaT   Perr
( 1) 4353  21239 00:52:38.401   78.0   60.9   -0.02     0.02    0.023
( 2) 4353  21239 00:52:38.441   77.9   60.9   -0.02     0.04    0.033
( 3) 4353  21239 00:52:38.600   77.7   60.9   -0.02     0.03    0.030
( 4) 4353  21239 00:52:38.920   77.2   61.0   -0.02     0.03    0.025
( 5) 4353  21239 00:52:38.960   77.2   61.0   -0.02     0.06    0.044
( 6) 4353  21239 00:52:39.241   76.7   61.0   -0.02     0.03    0.031
( 7) 4353  21239 00:52:39.561   76.2   61.0   -0.02     0.03    0.031
( 8) 4353  21239 00:52:39.600   76.2   61.0   -0.02     0.05    0.044
( 9) 4353  21239 00:52:39.761   75.9   61.0   -0.02     0.03    0.025
(10) 4353  21239 00:52:39.801   75.9   61.0   -0.03     0.04    0.041

rms     0.03367

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
NAVAREA XII 384/21(GEN).
EASTERN NORTH PACIFIC.
1. HAZARDOUS OPERATIONS, SPACE DEBRIS
   091627Z TO 091729Z AUG, ALTERNATE
   101716Z TO 101817Z AUG
   IN AREAS BOUND BY:
   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].

UPDATE: 

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.

UPDATE 2:

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...

UPDATE 3:

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.

Proton-M rb (2021-066B) reentry forecast (updated)

 (this post is updated when I have run new predictions)

click diagram to enlarge

The Proton-M third stage from the July 21 Nauka launch (see previous post) is coming down fast. The current reentry forecast models place the reentry into the atmosphere in the early hours of August 6 UT.

The diagram above shows CSpOC TIP data in red, and my own GMAT model results in black. My GMAT predictions in tabular form:

DATE         UT    +-        LAT    LON    orbit epoch
6-8-2021     9:55  1.8  day                28-7-2021 12:12
6-8-2021    16:51  1.7  day                29-7-2021 06:01
6-8-2021     9:18  1.4  day                30-7-2021 04:16
6-8-2021     8:29  1.2  day                31-7-2021 05:28
6-8-2021     9:47  1.0  day                 1-8-2021 05:09
6-8-2021    18:23   23  hr                  1-8-2021 22:54
6-8-2021    21:00   23  hr                  2-8-2021 03:19
6-8-2021    13:52   17  hr                  3-8-2021 00:31
6-8-2021    11:44   14  hr                  3-8-2021 16:12
6-8-2021     9:29   11  hr    15 S  177 W   4-8-2021 00:05
6-8-2021     7:50    8  hr    19 N  180 W   4-8-2021 15:44
6-8-2021     6:40    6  hr    38 S  108 W   4-8-2021 23:04
6-8-2021     6:26    5  hr     4 N  146 W   5-8-2021 03:27
6-8-2021     2:56  2.9  hr    25 N  112 E   5-8-2021 12:14
6-8-2021     5:07  2.5  hr    22 S  104 W   5-8-2021 16:37
6-8-2021     5:34  1.7  hr    29 S   24 E   5-8-2021 21:00
6-8-2021     4:49  1.6  hr    32 N  148 W   5-8-2021 21:00*

The last orbit was re-issued with an epoch almost similar to the previous orbit. This orbit is indicated by an asterisk and my final forecast.

Within current uncertainty windows, no meaningful prediction can be given about the location of the reentry yet. The values nevertheless listed in the tabe for latitude and longitude are nominal values only for the middle of the quoted uncertainty interval (which spans multiple revolutions around the Earth). Given the current uncertainty intervals, they are basically meaningless. Only an hour or so before the actual reentry, the uncertainty interval becomes less than one revolution.

The map below shows the nominal GMAT and last pre-reentry CSpOC TIP positions, plus the trajectory over the uncertainty window [EDIT: see update with final TIP at end of post!!!!]:

 

click map to enlarge

The rocket stage has a dry mass of about 4 tons and is about 4 x 4 meter wide. The diagram below shows the evolution of the orbital altitude of the rocket stage so far, based on CSpOC tracking data. Perigee is the lowest point in it's elliptical orbit around earth, apogee the highest point. Altitudes refer to the equatorial radius of the earth.

 

The last few orbits shows signs of trouble in determining the (quickly evolving) orbit (look at the perigee values for the last four orbits issued). The last available orbit was issued in two versions

 

click diagram to enlarge

 

On July 21, a few hours after launch, I filmed the Proton rocket stage during a pass over Leiden, accompanied by three pieces of debris that were never catalogued by CSpOC:

 

(EDIT: see update below movie!)

UPDATE: 

The final CSpOC TIP is in: 4:46 +- 1m UT (August 6) near 37.8 N 155.7 W, north of Hawaii (this is probably based on a SBIRS detection of the reentry fireball, given the very accurate +- of 1 minute).

This is very close to my last nominal GMAT estimate (4:49 UT near 32 N 148 W)! 

In all honesty: given the uncertainty intervals, that very good match is down to pure luck....

click map to enlarge

Nauka and it's Proton-M rocketbooster

 

click image to enlarge

On 21 July 2021 at 14:58 UT, Roscosmos launched the new MLM-NAUKA module for the ISS from Baikonur, using a 3-stage Proton-M rocket. After its arrival at the International Space Station (ISS) on July 29, it will replace the PIRS module. Docking is set for 13:24 UT on the 29th.

The NAUKA launch came much belated: originally slated for launch in 2007 (!) it was postponed several times, amongst others after a problem with iron fillings in the engine plumbing was discovered.

With NAUKA, also ERA, the European Robotic Arm, was launched.

In order to make room for NAUKA, the PIRS module was undocked on 2021 July 26 near 10:56 UT, and deorbitted (using Progress MS-16 as a 'tug') into the southern Pacific Ocean on July 26 near 14:42-14:52 UT:

click map to enlarge

Soon after launch, it became apparent that NAUKA was in trouble. There was an initial telemetry problem, and (very worryingly) the main engines didn't work. Russian flightcontrol eventually used the auxilliary engines to raise the module's orbit.

click diagram to enlarge

For European observers, the first few nights after launch offered good sighting opportunities for the free-flying NAUKA (2021-066A), it's Proton-M 3rd stage (2021-066B), and the ISS, the three on the first evening passing within a few minutes of each other in evening twilight.

The images below show NAUKA and the Proton-M 3rd stage in evening twilight of 22 July, imaged with a Canon EOS 80D + EF 2.0/35 mm lens (first Nauka, then the Proton rb):

click image to enlarge

click image to enlarge

The Proton rb, and initially NAUKA as well, were  passing through a very low perigee (initially 187 km for the RB, 195 km for NAUKA) over Europe on the first nights. As a result, they passed at a very high, zipping speed through the sky, which was quite spectacular to see. They were bright too.

The video below shows the Proton RB zipping through a partially clouded Leiden sky at 21 July. In the video, it can be seen that three debris pieces accompanied it (these debris pieces were not catalogued by Space-track). Because of the very fast movement (the rocket stage was at only 187 km altitude at the time!) the video is a bit chaotic: I had to continually adjust the camera pointing:

 

 

This framestack from a part of the video shows the three debris pieces:

I initially had bad luck filming NAUKA: on two evenings I though I had restarted the video camera recording, but didn't. I succeeded on 23 July however:

The videos were made with a WATEC 902H2 Supreme + Zeiss 1.4/35 mm lens.

My current estimate for the reentry date of the Proton-M 3rd stage is within 2 days of August 6, 2021. I will issue regular updates in a new post once we come closer to this date.

Nauka was found to broadcast telemetry on 631.0 MHz. This is a spectogram of signals I received at Leiden, the Netherlands, in the evening of 28 July during the 18:56 UT pass, using an antenna I had quickly whipped up from scratch for this frequency:

 

UPDATE 29 July 13:45 UT:

Nauka successfully docked to the International Space Station at 13:29 UT (July 29) near 45.5 N, 110.2 E at an altitude of 425 km above earth surface.

UPDATE 30 July

It looks like Nauka's long stretch of bad luck continues. After docking, at 16:34 UT (Jul 29) an emergency situation developed when Nauka's thrusters suddenly started to fire on their own, without command, causing the ISS to loose attitude control for a while. Thrusters on the Zvezda module were trying to counter the Nauka thruster's firing, and Russian flight controllers were franticly attempting to get the Nauka thrusters to stop firing. In the end, the situation resolved when Nauka ran out of fuel.

A possible missile test (AGM-183 ARRW, or not?) in the Pacific on July 10

 

Three related Navigational Warnings have appeared (NAVAREA XII  nr 304, 305 and 306) that together seem to define the trajectory of a missile test in the Pacific on July 10 between 9:00 and 18:00 UT, with a backup date on July 13:

 060344Z JUL 21
 NAVAREA XII 304/21(18).
 EASTERN NORTH PACIFIC.
 CALIFORNIA.
 1. HAZARDOUS OPERATIONS 100900Z TO 101800Z JUL,
    ALTERNATE 130900Z TO 131800Z JUL
    IN AREA BOUND BY
    33-08-45N 121-27-34W, 33-27-41N 121-29-48W,
    33-33-57N 120-11-14W, 33-14-46N 120-09-15W.
 2. THIS MSG 131900Z JUL 21.

 060353Z JUL 21
 NAVAREA XII 305/21(18).
 EASTERN NORTH PACIFIC.
 1. HAZARDOUS OPERATIONS 100900Z TO 101800Z JUL,
    ALTERNATE 130900Z TO 131800Z JUL
    IN AREA BOUND BY
    32-32-16N 129-10-43W, 32-08-05N 131-47-11W,
    31-53-04N 131-45-39W, 32-17-48N 129-09-11W.
 2. CANCEL THIS MSG 131900Z JUL 21.

 060445Z JUL 21
 NAVAREA XII 306/21(19).
 EASTERN NORTH PACIFIC.
 1. HAZARDOUS OPERATIONS 100900Z TOP 101800Z JUL,
    ALTERNATE 130900Z TO 131800Z JUL
    IN AREA BOUND BY
    31-13-21N 136-21-34W, 31-04-36N 137-16-57W,
    30-49-37N 137-15-27W, 31-01-22N 136-20-03W.
 2. CANCEL THIS MSG 131900Z JUL 21.

Below I have plotted the areas from these three Navigational Warnings on a map:

click map to enlarge

The three areas seem to define a ballistic trajectory for a missile fired, either from a ship, submarine or aircraft, in the Point Mugu Sea Range near the Channel Islands of California, in the general direction of (but maybe not as far as) Hawaii. The distance between the easternmost and westernmost area from the Navigational Warnings is about 1600 km. The distance to Hawaii is about 3950 km.

The question is whether the apparent line-up with the Pacific Missile Range Facility at Hawaii (for which there is a perpetual Navigational Warning) is coincidence or not (the map below shows a simple ballistic trajectory from the esternmost area in the Point Mugu Sea Range to Hawaii PMRF: the three areas and PMRF line up well):

click map to enlarge

If the line-up with Hawaii is coincidence, i.e. if we ignore a possible target area near Hawaii, then one option is that this is a flight test of the AGM-183A ARRW (Air-launched Rapid Response Weapon), a hypersonic missile launched from a B-52 aircraft. Little is known about the range of this new missile, and estimates differ: from 925 km to a quoted "almost 1000 miles". 

The latter is somewhat similar to the ~1600 km range between the easternmost area (NAVAREA XII 304) and westernmost area (NAVAREA XII 306) from the current Navigational Warnings. However, the similarity between "925 km" and "almost 1000" also makes me wonder whether kilometer and miles were mixed up in the latter statement. 1600 km equals 994 statute miles, or 863 nautical miles. 

Early June 2021, a test firing of AGM-183A was announced to probably take place this month (July 2021), which is one reason to suspect a connection of these Navigational Warnings to AGM-183.

If these Navigational Warnings indeed do refer the announced July AGM-183 test, then area 304 is where the missile is fired (from an airborne B-52), area 305 where the booster stage splashes down, and area 306 likely the missile target area.

The last (failed) test attempt of AGM-183A was in April, according to sources. It failed because the missile refused to separate from the aircraft.

The areas from the three July 10 Navigational Warnings are 100% identical those those of three earlier Navigational Warnings issued for May 17 (which I at that time, mistakenly probably, thought might be an SLBM test): Navigational Warnings NAVAREA XII nr 210, 211 and 212:

 

Some sort of (SLBM?) #Missile test in the Pacific is indicated in Navigational Warnings for May 17.
I've not been able to find a corresponding target area in the Marshall Islands so far.@planet4589 @nukestrat @wslafoy @mhanham pic.twitter.com/QP5neGR7DT

— Dr Marco Langbroek 💉x2 #Vaccinate (@Marco_Langbroek) May 13, 2021

So either there was an aborted/failed test attempt in May as well, or these warnings (both the current and those for May 17) do not refer to AGM-183A.

The AGM-183A ARRW is a hypersonic missile fired from a B-52 aircraft. A rocket stage initially propels it and brings it to high altitude at the edge of space (i.e. not as high as an ICBM which truly enters space), after which it glides down and attains hypersonic speeds up to 6.86 km/s. It is still in its experimental phase with, as far as known, no successful test flight yet.

AGM-183 under the wing of a B-52 during a Captive Carry test. Image: US DoD (Giancarlo Casem)

 

EDIT: just after I hit the "publish" button,  Hans Kristensen alerted me to the arrival of an Ohio-class Nuclear Missile submarine in San Diego at July 7th. So, maybe an SLBM test after all (but not a standard Trident-II D5 test then, as the positions of the drop zones do not match with earlier Trident tests).

UPDATE 11 July 2021:

This Navigational Warning cancelling warnings NAVAREA XII 304, 305 and 306 just appeared, the wording of which ("operations completed") suggests that something did take place:

101832Z JUL 21
NAVAREA XII 314/21(18).
EASTERN NORTH PACIFIC.
CALIFORNIA.
CANCEL NAVAREA XII 304/21, 305/21, 306/21
AND THIS MSG, OPERATIONS COMPLETED.