ACS 3 appears to be tumbling or gyrating

 

(this post was lightly editted and extended after initial posting)

In a previous post I reported my first post-sail-deployment observations of NASA's ACS 3 (2024-077B), the Advanced Composite Solar Sail System.

I observed the Solar Sail again in the evening of September 1, 2024, and this time the brightness of the Solar Sail was quite different. As it rose in the south, it became very bright, reaching magnitude 0 (as bright as the brightest stars in the sky). It then faded again, and next displayed a slow brightness variation with multiple bright maxima and very faint minima.

The video above, shot with my WATEC 902H2 Supreme camera and a Samyang 1.2/85 mm lens, shows some of the brightness variation (NOTE: the footage is not a continuous sequence!) with several peaks and valleys.

Below is a fragmentary brightness curve. During minima I lost the satellite a few times, and during maxima it was oversaturated (so the diagram does not capture the peak brightness well). The brightness seems to indicate a slow cycle of around half a minute:

 

click diagram to enlarge

 

The brightness variation could be suggestive of a slow tumble or wobble (a gyration around an axis) that must have been initiated after August 29, when it appeared more steady (apart from a brief bright flare, probably due to a favourable sun-sail-observer geometry). There might be other explanations though (which is why I use the word "appears" and "could").

Interestingly enough, in the orbital data a clear and sudden change can be seen after August 30.4 UTC, when the orbital eccentricity increased, and as a result both apogee and perigee changed (see diagram below). Perhaps that was the moment the tumble or wobble, if it is one, started. It will be interesting to see whether it stabilizes again over the next days.

It is to be expected that once the solar sail is unfurled, the Solar Radiation Pressure acting upon it will cause the orbit to change (that is the whole point of the solar sail experiment). That is likely what we see here. The orbital change started ~0.8 days after sail deployment, so that might perhaps be the moment they reoriented the sail to take advantage of the SRP to change the orbit. The ACS 3 mission blog on August 29 indeed wrote that "during the next few weeks, the team will test the maneuvering capabilities of the sail in space".

click diagram to enlarge

The Advanced Composite Solar Sail System 3 (ACS 3) observed after sail deployment [UPDATED]

ACS 3 on 29 August 2024. Click to enlarge

 

On April 23, 2024, Rocketlabs launched an Electron rocket for NASA carrying ACS 3 (2024-077B) , the Advanced Composite Solar Sail System, into a 994 x 1023 km, 97.4 degree inclined Sun-Synchronous orbit. 

ACS 3 is a 12U cubesat carrying a deployable 9.9 x 9.9 meter solar sail with a total effective surface of 80 m² . The sail is very thin (2.115 micrometer). For more information on the mission  see here on the mission page, and this scientific paper here.

Due to power issues it took a while (over 4 months) before the sail was actually deployed. That happened on August 29 and was completed near 17:33 UTC.

Three hours after the deployment, I observed a pass of the spacecraft over my home in Leiden, the Netherlands, near 20:26 UTC (August 29).

The image above shows the solar sail near peak brightness, ascending over my rooftop near 20:26:42 UTC (August 29). The image was taken with a Canon EOS 80D + Samyang 1.4/35 mm lens at F2.0 and ISO 800 with an exposure time of 5 seconds.

It was not very bright, briefly reaching magnitude +3 (moderate naked eye visibility) but for most of the pass it was much fainter (below naked eye visibility).  Nevertheless, it has become much brighter than before sail deployment,( see below), as was to be expected, by at least 4-5 magnitudes.

The observation was during a west pass in the evening, i.e. not the most favourable illumination angle. It is possible (I haven't had the opportunity to re-observe it yet) that it is brighter during an evening east pass. Given that it is a flat reflective sail, it is also possible that under specific circumstances a narrow strip on Earth might see a much larger brightness. On the other hand, the reflective coating of the sail is pointing towards the sun, away from earth.

I had targetted the object a couple of times earlier over the past few months, before the sail was deployed, using the WATEC 902H2 Supreme and a 1.2/85 mm lens. Most of the passes it was beyond visibility: on two occasions, I had a positive but very faint detection of the 12U cubesat bus plus solar panels. As it orbits at 1000 km altitude, the bus was much less easy to detect that other cubesats that are usually in lower orbits (400-500 km).

Below is a framestack from a positive detection on May 3, 2024 (see also this earlier post), when it was briefly but very faintly seen with a brightness near magnitude +9.5. The very faint trail can be seen in the lower right of the image:

click to enlarge

Over the coming months, the solar sail will be used to manoeuver the spacecraft. They will first raise and then lower the orbit, using the Solar Radiation Pressure (SRP) on the sail as propulsion. They expect to be able to change the semi-major axis this way by up to 1-2 km/day.

I vividly remember observing another experimental solar sail, Nanosail-D in 2011, which was in a lower orbit and quite bright in twilight, with a stroboscopic flash pattern due to tumbling (see amongst other this earlier post from 2011). 

 

UPDATE 2 Sept 2024:

On September 1, I observed the Solar Sail again and this time it was much brighter and showed clear brightness variations perhaps indicating tumbling or a gyration. More in this follow-up post.

More X-37B spaceplane OTV 7 observations

OTV 7 imaged on August 11. Click image to enlarge

In a previous blogpost I wrote about recovering the X-37B Spaceplane OTV 7 (2023-210A) on July 30. I have now observed it a couple of times, at intervals of a few days due to a combion of weather conditions and favourable or less-favourable pass times. Above is an image from August 11. The diagram below shows where it was in its orbital position at that time, coming down from apogee:

click image to enlarge

 

Between mid-March and end-of-July, OTV 7 had brought down its apogee by a few thousand kilometers. Since recovery on July 30, it is continuously making smaller manoeuvers as well (currently, it seems to make small orbit raising manoeuvers adjusting both apogee and perigee). As a result, it is invariably off predictions (usually being a bit 'late') and a small plane scan is necessary to recover it. Having a wide-field instrument (the FOV of the instrument I currently use, an ASI 6200 MM PRO with 1.2/85 mm lens, is 24 x 16 degrees) is useful in this aspect.

The brightness of OTV 7 strongly depends on where it is located in its orbit during observation (as well as, of course, phase angle and condition of the local sky). When it is in or near apogee, it is fainter and the trail is short.

When following the object over (a part of) a pass, the brightness and apparent angular rate of movement (trail length) notably changes. How clearly it can be seen in the imagery is complex interaction of actual brightness, apparent angular movement (when it moves faster, each image pixel is illuminated less), range to the observer and phase angle.

Below are two images from the night of August 14-15, some 3 hours after OTV 7 passed apogee. The second of these images shows OTV 7 not far from M31, the Andromeda galaxy. Even though the two images are not at the same image scale (the one with M31 is reduced in size, to show a wider FOV), the difference in trail length after a mere half an hour can already be seen (both images are 10-second exposures with a ZWO ASI 6200 MM PRO and Samyang 1.2/85 mm lens).

Recovery of the X-37B spaceplane OTV 7

click to enlarge

 

The classified US Space Force X-37B spaceplane OTV 7 (2023-210A) was launched on 29 December 2023, in an unusual Highly Elliptical Orbit. Five weeks after launch, in the first week of February 2024, it was found on-orbit by Tomi Simola from Finland in a 38600 x 300 km, 59.15 degree inclined orbit (see this earlier blogpost). We followed it for a month and then lost it: the last observation was on March 15.

But now it has been recovered! On the night of July 30-31, I was imaging geosynchronous objects when I noted a short trail made by an unidentified interlooper.  Mike McCants identified the UNID as OTV 7.

The image in top of this post (one out of four images spanning half an hour) shows the short faint trail created by OTV 7. The ~9 by 4.5 meters large X-37B spaceplane was near apogee of its orbit at that time, at about 35535 km altitude (and a range of some 38775 km to my observing location). The image is a 10-second exposure with a ZWO ASI 6200 MM PRO and Samyang 1.2/85 mm lens, and shows only a small part of the original image. It was taken from Leiden, the Netherlands.

Weather next initially conspired against me, but last night, August 3-4, I again observed it, some 25 minutes late on the initial elset estimate. This is a small part of one of the images, shsowing the faint trail created by OTV 7:

click image to enlarge

The observing conditions were very dynamic this time: after rainshowers, small but bright, stamp-sized clearings were sometimes present in the clpud cover. I managed to image the object through such gaps in the cloud cover a few times over an half-an-hour-period, 25 minutes late on the preliminary orbit. 

Below is an example of what I am talking about when I say "stamp-sized clearings": this is the last image (reduced in size as the true image is 9576 x 6388 pixels) on which I could find it. All the white is clouds....:

click to enlarge

The new observations constrain the orbit a little bit better: 314 x 35552 km, 59.15 degree inclined. A provisional elset:

OTV 7
1 58666U 23210A   24216.90625742 0.00000000  00000-0  00000+0 0    01
2 58666  59.1511 329.1636 7247171 178.5736 186.3429  2.29027449    03

rms 0.004 deg   from 9 obs, arc July 30.96 - Aug 3.96 UTC

Below is a comparison between the (forward propagated) orbit from March (red), and the current orbit (white). Apogee is some 2300 km lower than it was in March (and this is not due to natural orbital decay, but due to manoeuvering). The orbital plane itself is still similar.

click image to enlarge

The Russian SIGINT satellite LUCH (OLYMP) 2 has arrived at its new destination, next to THOR 7

LUCH (OLYMP) 2 imaged at its new location on July 6. Click image to enlarge

 

In a previous blogpost I signalled that the Russian military SIGINT satellite LUCH (OLYMP) 2 (2023-031A), also known as LUCH-5X, a satellite that stalks other satellites, started another relocation move on July 22, leaving its position near ASTRA 4A at longitude 4.8 E and drifting west at 0.9 degrees per day. 

On July 1, the drift stopped as it arrived at its new target destination at longitude 0.54 W. As expected, it has been placed close to yet another western commercial geosynchronous satellite: the Norwegian satellite THOR 7 (2015-022A).

The image above shows both satellites - plus a couple of other neighbouring ones - as imaged by me from Leiden in the night of July 6/7, when I finally had clear skies again, albeit briefly. The image is a 10-second exposure taken with a ZWO ASI 6200 MM PRO + 1.2/85 mm lens. 

At the moment the image was taken, LUCH (OLYMP) 2 and THOR 7 were some 84 km apart. That distance might diminish further: the Russian satellite is still slowly drifting closer to THOR 7.

This is the sixth relocation of LUCH (OLYMP) 2, and the fifth satellite it visits (see diagram above). I expect that it will stay close to THOR 7 for a few weeks and then move on again, possibly to one of the neighbouring satellites (THOR 5 or 6, or INTELSAT 1002), or to a new location altogether.

I also imaged LUCH (OLYMP) 1 (2014-058A), the predecessor of LUCH (OLYMP) 2 (see image below). It has been parked close to INTELSAT 37E (2017-059A) at longitude 18.1 W since September 2022, following an earlier life of frequent relocations (some 30 relocations between 2014 and 2022):

 

LUCH (OLYMP) 1 near INTELSAT 37E on July 6. Click image to enlarge

More on both LUCH (OLYMP) 1 and 2 and their program backgrounds can be found in this article from 2023 by Bart Hendrickx in The Space Review.

As I wrote in a previous blogpost, what LUCH (OLYMP) 2 and its predecesssor LUCH (OLYMP) 1 are doing so close to commercial satellites is an interesting issue. To name a few possibilities: they might be gathering information to map contact networks; geolocating targets that use the satellites; eavesdropping on data communications; prepare for or actually do jamming or spoofing activities; or checking these satellites for vulnerabilities that might provide a means to disable them, might need come.

LUCH (OLYMP) 2 is on the move again [UPDATED]

Image from June 27, 2024. Click to enlarge

 [ UPDATED on 5 July 2024 ]

The Russian military geosynchronous SIGINT satellite LUCH (OLYMP) 2 (2023-031A) is on the move again. It has left its position at longitude 4.7 E with a manoeuver initiated on 22 June 2024, likely around 11:40 UTC. It is now drifting westwards with a drift rate of approximately 0.9 degrees per day. 

The change in several orbital elements after mid June 22 is well visible in the TLE data:

It will be interesting to see what LUCH (OLYMP) 2's next stalking victim will be.

LUCH (OLYMP) 2, which was launched on 12 March 2023, is building a history of frequent relocations, like its predecessor LUCH (OLYMP) 1 (2014-048A) did. With each relocation, it is placed close to a commercial satellite. Below shows the position it had between April 1 and June 22 close (daily varying between 20-75 km) to ASTRA 4A at 4.7 E, where it arrived on April 2, 2024 (see this earlier blogpost) until it left there on June 22. 

 

 

So far LUCH (OLYMP) 2 has stalked at least four commercial satellites:

ARRIVED      LEFT         LON      NEXT TO
22-05-2023   25-09-2023   9.0 E    EUTELSAT (KA SAT) 9A/EUTELSAT 9B
04-10-2023   04-12-2023   3.2 E    EUTELSAT 3B
05-12-2023   26-03-2024   2.6 E    EUTELSAT KONNECT VHTS
01-04-2024   22-06-2024   4.7 E    ASTRA 4A

Below, the movements since launch in diagram form, showing the longitude of placement The first two placements at 78 E and 58 E were probably check-out placements.

click diagram to enlarge

What LUCH (OLYMP) 2 (and its predecesssor LUCH (OLYMP) 1) is doing so close to commercial satellites is an interesting issue. To name a few possibilities: it might be gathering information to map contact networks; geolocating targets that use the satellites; eavesdropping on data communications; prepare for or actually do jamming or spoofing activities; or checking these satellites for vulnerabilities that might provide a means to disable them, might need come.

 

UPDATES 5 and 7 July 2024

The westward drift of LUCH (OLYMP) 2 stopped on July 1, at longitude 0.54 W, where it has now stabilized its position. LUCH (OLYM) 2 is now close to the Norwegian commercial geosat THOR 7 (2015-022A). Due to bad weather, I have not been able to image it there yet. I imaged it at its new position on July 6/7, see this new blogpost.

The North Korean satellite Malligyong-1 raised its orbit again early June

 

click diagram to enlarge

Early February 2024, the North Korean satellite Malligyong-1 (2023-179A) made a series of orbital raising manoeuvers, the first we have ever seen a North Korean satellite do. I wrote about the character and significance of it at the time in two brief articles in The Space Review, which you can read here (part 1) and here (part II).

And now Maligyong-1 has raised its orbit again, in early June, slightly over 3 months after the February orbit raise. As was the case for the February orbit raise, it was done in five increments, one on each successive day, the first incremental raise in this series happening on June 3 and the last on June 7, 2024. The fifth and last of the June incremental raises also raised the apogee, by 1.6 km, something that did not happen during the previous orbit raise in February.

click diagram to enlarge

 

Each incremental raise raised the average orbital altitude by about 1.15 kilometer, for a total orbit raise of 5.8 kilometer. Perigee was raised by 10 km in total, apogee by 1.6 km. The series of incremental raises lifted the orbit to 504 x 502 km. The average orbital altitude was lifted to 503 km, half a kilometer higher than the initial insertion orbit from November 2023 (see diagram below). The new manoeuvers also further circularized the orbit (see diagrams above).

As was the case for the February manoeuvers, the orbit raise effectively compensates for the loss in orbital altitude due to natural orbital decay since February (and since launch in November 2023), maintaining the orbit within the preferred operational altitude limits.

In addition to raising the orbit back to its initial altitude, and further circularization of the orbit, the current series of orbit raises also served to bring the rate of RAAN precession even closer to the ideal sun-synchronous value than it was before. The orbit has a repeating ground track after 76.007 revolutions, i.e. each 5 days.

click diagram to enlarge

 

From what we have observed so far, we now likely can expect periodic orbit maintenance raises to happen about each three months, The first orbit maintenance raise in February 2024 was three months after launch, and the current second orbit maintenance raise three months after the previous. 

The next orbit raise therefore probably will happen near mid-September 2024.  

Both in February and June, the first sequential raise was on a Monday and the last on a Friday. We might therefore likely see the next orbit raise initiate on Monday 9, Monday 16 or Monday 23 September, 2024.

Like I did for the sequential orbit raises in February, I tried to reconstruct the approximate moment and location for each sequential burn between June 3 and 7. 

For the February series of orbit raises, I found that all incremental raises appeared to correspond to late local evening passes within direct line-of-sight of the Satellite Control Center in Pyongyang (see this article in The Space Review). 

The tracking data available for this series are a bit more sparse than for those in February (especially around the third incremental raise), yet when doing a similar analysis for this series a very similar pattern emerges again: all manoeuvers occurred around 13h-14h UTC (22h-23h local time), one of two moments in the day when the orbital plane of the satellite is passing over North Korea.

click map to enlarge

Nominal calculated manoeuver locations (for the method, see here) are all either in the area where the satellite is above the horizon as seen from North Korea, or close enough to it that they in reality very likely were too, taking uncertainties into account. The third incremental manoeuver (green) does not, but tracking coverage around that specific manoeuver is sparse, so that determination is a bit suspect.

Each line on the map above depicts the satellite's ground track from 10 minutes before, to 10 minutes after the nominal calculated manoeuver moment. The red circle is the boundary of the range where the satellite is above the horizon as seen from Pyongyang. Two out of the five nominal calculated manoeuver positions are within this circle, three are not. But even though for these three the calculated nominal manoeuver point is not within this circle, the satellite would have passed within the circle within minutes of the calculated manoeuver time on two of the three occasions, as can be seen from the mapped T-10m to T+10m ground tracks.

The Chinese robotic Space Plane 3 and Object G: proximity operations [MULTIPLE UPDATES]

(blogpost updated on June 6, June 14, June 17 and June 23, 2024. Last update at bottom)

 

The video above shows 2023-195A, the third mission of China's experimental spaceplane (aka "PRC Test Spacecraft", aka "Reusable Test Vehicle") and "Object G" (2023-195G), an object it ejected late May 2024. 

The video was taken  from Leiden, the Netherlands, in evening twilight of June 8, 2024, using a WATEC 902H2 Supreme camera and Samyang 1.2/85 mm lens. 

Object G is the faint object in front, the brighter object is the Space Plane.

I had also observed both objects a day earlier, on the evening of June 7, in deep twilight. Below is a frame stack from that June 7 observation: object G is the fainter of the two streaks and was just in front of the Spaceplane:

Object G was first catalogued on May 25. My analysis shows that it was ejected from the Spaceplane on May 24 near 18:40 UTC, during a pass over China. 

Directly after ejecting it, the spaceplane made a manoeuver, raising its orbit by about 1 kilometer. This likely was an avoidance manoeuver, i.e. a manoeuver to avoid hitting the object it just ejected.

In the first few days after ejection, the 18th STS appears to have  confused both objects: orbital data for object G and the spaceplane between epoch 24146.6 and 24148.9 have been switched, and what is labelled as "PRC Test Spacecraft 3" in the catalogue during this period is actually Object G, and vice versa.

Below are two diagram of the apogee and perigee evolution for both objects: one "as is" following the catalogue identities: and a second one where I have corrected the identities of both objects during the period they were switched:

click diagram to enlarge

click diagram to enlarge

Looking at the orbital behaviour of both objects, it appears that Object G does not noticably manoeuver. Its parent the spaceplane did: between June 5 and June 7, starting eleven days after it ejected Object G, the space plane made a series of (phasing) manoeuvers, as can be seen in the diagram above. It first lowered its orbit, and then raised it again a day later. The result is an orbit at similar altitude and orbital period as Object G, but slightly more eccentric.

Another effect of those manoeuvers was that it brought the spaceplane and Object G in close spatial proximity again, with a separation of only a few kilometers (as can be seen in the video imagery in top of the post, taken when both objects were some 7-8 km apart). It is possible that the spaceplane did briefly retrieve Object G or attempted to do so, and then let it go again, but this cannot be unequivocally confirmed from the orbital data. Some combinations of the orbital data for epoch 24160 do suggest that a potential very close approach at kilometer level or even less might have happened on 8 June near 14-15h UTC. The rapid manoeuvering evident from the clear orbital changes in successive elsets from June 8-9 makes it however difficult to validate true distances and exact times involved.

It is clear however that between June 5 and 7, the spaceplane manoeuvered with the intent to do a proximity operation with Object G on June 8, bringing the two objects to within a few kilometers of each other.

It will be interesting to see whether or not the spaceplane will periodically adjust its orbit to remain in the vicinity of Object G. [see update at bottom of post!]

The spaceplane was launched from Jiuquan with a Long March 2F rocket on 14 December 2023, initially into a 348 x 332 km, 50.0 degree inclined orbit. On January 5, it made a small orbit raise to 359 x 331 km. On 19 January 2024, it significantly raised its orbit to 597 x 334 km. On 26 January 2024, it circularized its orbit to 609 x 602 km (see diagram of orbital evolution below). On May 24, it spawned Object G.

click diagram to enlarge

 

The spacecraft is a robotic spaceplane capable of landing on a runway after deorbit, and China's answer to the US X-37B OTV spaceplane. It is launched on a rocket from Jiuquan, and after spending time on orbit, it lands again on a 5-km long runway near Lop Nur in the Taklamakan desert (see Sentinel satellite image below). 

 

Lop Nur runway (Sentinel 2B image). Click to enlarge

The current mission is the third mission of this type of spacecraft: it did a short 2-day mission in August September 2020, and a much longer 276-day mission between August 2022 and May 2023. The current mission has been on-orbit for 181 days (status June 12, 2024).

 

UPDATE 14 June 2024

On June 11 near 9 UTC and June 12 near 10 UTC, the spaceplane again made phasing manoeuvers, followed by a series of smaller orbit adjustments that have now brought apogee and perigee altitudes (and with that eccentricity and orbital period) very close to those for Object G.

The June 11 and 12 manoeuvers caused another very close approach (to a km or less), i.e. another proximity operation, between the spaceplane and Object G on June 12 near 13 UTC.

click diagram to enlarge

UPDATE 17 June 2024

The spaceplane keeps manoeuvering for new proximity operations with object G. A new close approach (a kilometer or less) was made on June 14 near 10:08 UTC, a next one might have happened on June 16 near 5:40 UTC, and another one might occur within hours of posting this update, on June 17 near 13:12 UTC.

 

click diagram to enlarge

UPDATE 23 June 2024

While the dates are generally reliable, the exact approach times I earlier listed might on hindsight not always be that accurate (hence why I crossed them out in this post update). The spaceplane likely frequently made orbit adjustments, and not all of those are well captured by the available tracking data. The approach times calculated depend clearly on which set of orbits you take, even for epochs close together in time.

The orbital periods of both objects - spaceplane and object G - are now very similar, and as a result they stay in each others vicinity, at a general distance of about 100 km at the time of writing (June 23), a distance which is very slowly increasing over time. The spaceplane's orbit is slightly more eccentric than that of object G.

click diagram to enlarge

 

There is an interesting pattern in the inclination of the object G orbit data, but I am not certain whether it is real or an artefact. There are minute  'jumps' in the inclination of object G that appear to coincide with dates of close approaches by the spaceplane. Given the earlier initial confusion between the object A and G identities, I remain cautious on whether or not these are significant.

Gazing in my crystal ball: at what time will North Korea launch Malligyong-2? [UPDATED]

click to enlarge

 

I have been gazing in my crystal ball to come up with an educated guess of the launch time (and with that, the possible orbit) of Malligyong-2, the upcoming North Korean satellite launch (see previous post).

The Navigational Warnings for the launch are similar to those for Malligyong-1 (2023-179A, (see previous post), which was launched on 21 November 2023 and is orbiting in a sun-synchronous morning orbital plane. So it is likely that Malligyong-2 goes into a similar 97.4 degree inclined, 512 x 493 km sun-synchronous orbit.

It would make sense however if  Malligyong-2 would not be launched into the same orbital plane in terms of RAAN, but rather target a complementary orbital plane. [but:see update below...]

The Malligyong-1 orbital plane is currently making daytime passes over Pyongyang around 10:13 local Pyongyang time. It is a morning plane (meaning: daytime passes in the local morning, near 10 am).

Two options are then in order for Malligyong-2: one is launch into an afternoon plane complementary to the Malligyong-1 morning plane (i.e. resulting in passes with a  similar solar elevation but in the afternoon, mirroring the morning passes). The other is launch into a noon plane, roughly inbetween the two.

The image above depicts the afternoon variant relative to the Malligyong-1 orbit. The noon plane is the mid-line of the globe.

Assuming launch on May 28, the afternoon plane option would mean launch around 5:37 UTC (14:37 local Pyongyang time) and this resulting approximate orbit:

MALLIGYONG-2                  for launch on 28 May 2024  05:37:00 UTC
1 70000U 24999A   24149.67289979  .00008068  00000-0  36481-3 0    07
2 70000  97.4276 275.3747 0014260 279.3296  80.6327 15.21105052    08

Of course this remains speculation, fueled by my OCD desire for neat constellations...

We'll see when launch happens (and if it is successful).

 

UPDATE: 

Launch actually appears to have been May 27, 14:50 ~13:45UTC, and failed. I guess my crystal ball is over its expiration date....
The time of launch is actually consistent with launch into the same RAAN plane as Malligyong-1.

UPDATE 2:

The North Korean State Press Agency KCNA calls the satellite in the failed launch "Malligyong-1-1" and indicates first stage failure caused the mishap, related to the "reliability" of a new LOX + petroleum engine. The wording is somewhat ambiguous on whether it concerns a new kind of rocket or a Chollima-1 stage: they do not name the rocket type, but mention a "new-type satellite carrier rocket".

It should be noted that during the previous Malligyong-1 launch, the Chollima-1 first stage also blew up, somewhat after separation of teh second stage (so it did no harm to the payload at the time). Here is footage of that occasion.

New North Korean launch (Malligyong-2) upcoming [UPDATED]

click map to enlarge

Navigational Warnings (HYDROPAC 1800/24) have appeared for a new North Korean satellite launch, the launch of their second military reconnaissance satellite Malligyong-2, from Sohae. North Korea also informed the Government of Japan of the upcoming launch.

The three hazard areas A to C  from the Navigational Warning are the same as those for the Malligyong-1 launch half a year ago (21 November 2023 - see this earlier blogpost). Quite likely therefore, the launch will go into a similar 97.4 degree inclined, 512 x 493 km Sun-synchronous orbit. Stage 2 and stage 3 will do a double dogleg.The launch window runs to June 3.

It will be interesting to see what the RAAN of the orbital plane will be in relation to that of Malligyong-1.

This is the text of the Navigational Warning:

261806Z MAY 24
HYDROPAC 1800/24(GEN).
PHILIPPINE SEA.
YELLOW SEA.
CHINA.
DNC 11, DNC 23.
1. HAZARDOUS OPERATIONS, ROCKET LAUNCHING
   IN PROGRESS UNTIL 031500Z JUN
   IN AREAS BOUND BY:
   A. 36-06.93N 123-33.12E, 35-24.52N 123-22.78E,
      35-20.02N 123-48.62E, 36-02.43N 123-59.18E.
   B. 34-05.90N 123-01.98E, 33-23.47N 122-51.88E,
      33-16.53N 123-29.67E, 33-58.97N 123-40.07E.
   C. 14-54.17N 128-40.10E, 11-19.30N 129-10.83E,
      11-26.82N 129-54.13E, 15-01.70N 129-24.05E.
2. CANCEL THIS MSG 030600Z JUN 24.

UPDATE: further speculation as to what could be the launch time in a follow-up post here.

UPDATE 2:  launch was near 13:50 UTC (May 27, 2024) and failed due to in-flight explosion of the first stage.

UPDATE 3: The North Korean State Press Agency KCNA calls the satellite in the failed launch "Malligyong-1-1" and indicates first stage failure caused the mishap, related to the "reliability" of a new LOX + petroleum engine. The wording is somewhat ambiguous on whether it concerns a new kind of rocket or a Chollima-1 stage: they do not name the rocket type, but mention a "new-type satellite carrier rocket" . 

It should be noted that during the previous Malligyong-1 launch, the Chollima-1 first stage also blew up, somewhat after separation of the second stage (so it did no harm to the payload at the time). Here is footage of that occasion.

The NROL-146 payloads: observing the 'train' of 21 Starshield satellites

On May 22, 2024, at 08:00:20 UTC, SpaceX launched a Falcon 9 from Vandenberg SLC-4 as NROL-146, carrying 21 classified payloads for the NRO.

It is the first operational launch of a 'proliferated architecture' (meaning: launching a lot of the same payloads, creating redundancy and with that less vulnerability to failure or countermeasures). The mission motto was: 'Strength in Numbers'.

Based on previous SDA Tranche 0 launches, I initially guessed that they would go in a ~900 km orbit. But on May 22 near 23:08 UTC, Spanish meteor cameras operated by the SPMN recorded a Starlink 'train' like phenomena low in the northern sky, with the 'train' entering Earth shadow around 23:08:10 UTC. I identified it as likely NROL-146, as the orbital plane would indeed pass over southern Europe around the time of observation. Time of observation and shadow entry itself however suggested a much lower orbital altitude, near 300 km, than my initial estimate.

The next two days I was clouded out, but yesterday evening (25-26 May), the sky finally cleared. Just after local midnight, I observed the 'train' from Leiden, counting 21 objects that passed over a 4-5 minute timespan. The 4-minute video above shows all 21 objects. They were very bright (magnitude +2 to +3).

If you get a 'Starlink'-vibe from the video, that is because they basically are. Built by SpaceX and Northrop Grumman, "Starshield" is a military version of Starlink, likely built on the same type of bus. 

Observations so far suggest they were launched into a ~310 km, 69.7 degree inclined orbit. Over the coming days and weeks they will disperse along their orbital plane, and likely also raise their orbital altitude.

click to enlarge

Below is a very cautious elset for the leading object:

NROL-146 obj A                                           310 x 311 km
1 70006U 24999A   24146.90436495 0.00000000  00000-0  00000+0 0    05
2 70006  69.7199  66.3577 0000678 155.5007 204.6228 15.87074186    05

The Russian KOSMOS 2576 launch of May 16, and USA 314: another 'inspector satellite'? [UPDATED]

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 (this blogpost reflects discussions with and information provided by Bart Hendrickx, Bob Christy and Jonathan McDowell)

In a previous blogpost I wrote about a Russian launch into SSO from Plesetsk on May 16. According to Roscosmos, the launch was at 21:21:29 UTC.

Based on the Sun-Synchronous orbit indicated by the launch azimuth I initially suspected this to be a new IMINT mission, but now I am not so sure. 

IMINT is part of it, but not all, and the primary payload, KOSMOS 2576, might actually be another inspector satellite, this time targetting the American KH-11 ADVANCED CRYSTAL spy satellite USA 314 (2021-032A), as suggested by Bob Christy.

The launch inserted at least 9 objects into space (2024-092A to J), and possibly more: all in basically the same orbital plane (with small subgroups), but at different orbital altitudes. Based on the nine objects catalogued so far (status 20 May 2024), four groups can be discerned, based on orbital period and inclination:

GROUP     ORBIT (km)  INC     PERIOD   OBJECT(S) possible ID
I         451 x 435   97.25   93.45    A         KOSMOS 2576
II        796 x 780   98.59   100.62   G,H,J     Rassvet
IIIa      552 x 532   97.59   95.52    D,E,F,K   SITRO-AIS
IIIb      548 x 531   97.59   95.45    B,C       Zorkiy 2M

As expected, Roscosmos has announced the primary military payload to be designated KOSMOS 2576. It is likely object A (see below) that stands out as a lone object in orbital altitude and inclination. 

Also part of this launch, according to sources, are three civilian Rassvet satellites that provide high speed internet connectivity; and (as announced by Sputnix) two civil Zorkiy 2M earth observation satellites, and four civil SITRO-AIS satellites (the latter six all cubesats). This means that at least one satellite has not been catalogued yet, if these numbers are correct. [edit: this fourth satellite has now also been catalogued, as object K]

To make it even more complex, some analysts believed the launch to have included three military Razbeg Optical reconnaissance satellites as well. But this now seems less likely.

The orbital plane that the primary payload, Kosmos 2576 was launched into, might not be random. As was first pointed out by Bob Christy, the orbital plane closely matches that of the American KH-11 ADVANCED CRYSTAL spy satellite USA 314 (2021-032A).

In the past, we have seen this happen before. In August 2022, Kosmos 2558 was inserted into the orbital plane of the American KH-11 spy satellite  USA 326 (see this earlier blogpost), making close approaches each 5 days. Earlier, in 2020, Kosmos 2542 and its spawn Kosmos 2543 were inserted into the orbital plane of the American KH-11 spy satellite USA 245, also making close approaches.

Object A, the primary candidate for Kosmos 2576, differs in RAAN with USA 314 by only 0.02 degrees, and in inclination by only 0.8 degrees. Its current orbital altitude (451 x 436 km) is lower than that of USA 314 (769 x 548 km), but both orbital altitude and inclination are the same as that of a previous 'inspector satellite', Kosmos 2558 (see earlier blogpost). Object A might raise its orbit in the future or, like Kosmos 2542 did in 2020, spawn a second satellite that moves upwards in orbit. It will be interesting to see what object A will or will not do in the near future.

click to enlarge

The reason to see the lone group I object, object A as the primary payload (Kosmos 2576) is the following: 

First, as already mentioned, its orbital plane closely matched that of USA 314, and as Bob Christy noted,  its orbit in terms of altitude and inclination closely matches that of a previous 'inspector satellite' that targetted a US KH-11 satellite, Kosmos 2558. 

Second: when propagated backwards to the time of launch, the object is placed close to Plesetsk; and its orbital plane passes right over the stage deorbit area from Navigational Warning NAVAREA XII 330/24 in the Pacific Ocean (see map below, and see also previous post for maps and discussion), related to the initial launch phase. This indicates that object A is the primary payload and the first of the objects to be released into orbit. 

click m ap to enlarge

 

By contrast, the three group II objects (G, H, J) at ~780 km do not match the deorbit area in the Pacific well at all (as can be seen in the map above), and back-propagated to the launch time they do not come out near Plesetsk. This indicates manoeuvers before their orbit insertion.

The orbital insertion sequence of the various objects from this launch was probably as follows:

(1) launch into 97.24 inclined, 435 x 451 km orbit, insertion of object A (primary payload);
(2) manoeuver up into 98.59 inclined, 780 x 796 km orbit, insertion of objects G,H,J (secondary payloads);
(3) manoever down into 97.59 inclined, 535 x 552 km orbit, insertion of objects D,E,F,K;
(4) slightly lower apogee, no inclination change, 531 x 548 km orbit, insertion of objects B,C;
(5) Fregat stage deorbit reentry ~10h 20m after launch.

The reasoning behind this sequence is the following:

In addition to the Navigational Warnings which I discussed above and in a previous post, Bob Christy found a NOTAM in the Indian Ocean which is likely for the Fregat stage deorbit, with a time window starting some 10 hours after launch (suggesting a prolonged coast phase and/or multiple manoeuvers):

F1791/24 NOTAMN
Q) YMMM/QWMLW/IV/BO/W/000/999/2815S07736E500
A) YMMM
B) 2405170700 C) 2405220900
D) DAILY 0700-0900
E) ROCKET LAUNCH FROM RUSSIA WILL TAKE PLACE
FLW RECEIVED FROM GOVERNMENT OF RUSSIA:
THE MINISTRY OF DEFENSE OF RUSSIA PLANS TO LAUNCH MISSILE IN THE
SPACE AND TO SINK ITS FRAGMENTS IN THE WATERS OF THE OCEAN.
CHARACTERISTICS OF IMPACT AREA:
3521S07521E
2100S07900E
2109S07936E
3530S07603E
3521S07521E
F) SFC G) UNL
CREATED: 14 May 2024 12:33:00
SOURCE: YBBBZEZX

The orbital plane of the group III objects (see table earlier in this post) B, C, D, E,  F and K passes over this area, 10h 20m after launch (i.e. near 7:40 UTC, May 17).This could indicate that these objects were the last to be released, before deorbit of the Fregat stage. The orbital planes of group I and II do not match this deorbit area that well, passing somewhat east and west of it. 

click map to enlarge

 

This leaves group II objects G, H J, the ones in the highest orbit (~780 km), whose orbital plane matches neither the Pacific Ocean nor Indian Ocean deorbit areas particularly well. This indicates manoeuvers both before and after their release, suggesting their orbital insertion was between that of group I and group III.

As to the possible identities of the objects from group II, IIIa and IIIb:

The orbital inclination and period (95.45 minutes and 97.6 degrees) of the two group IIIb objects (B, C) match those of two objects (2024-092B and C) from a previous launch that included Zorkiy 2M satellites. So objects B and C of the current launch are probably the two Zorkiy 2M payloads.

The orbital inclination and period  (95.52 minutes and 97.6 degrees) of the three group IIIa objects (D, E, F, K) match those of both earlier Rassvet and SITRO-AIS launches, but their number matches the number of SITRO-AIS payloads announced in this launch.

The three group II objects (G, H, J) in the higher ~780 km orbit match neither previous Rassvet, SITRO-AIS or Zorkiy 2M launches. But by a process of ellimination they must be the three Rassvet payloads announced - if there are no other objects catalogued in the future.

The picture presented here might be revised if more objects are catalogued. For now, this is my best interpretation. It will be particularly interesting to see what object A will do.

 

UPDATE 22 May 2024:

US United Nations ambassadeur Robert Wood has, in a May 20 UN Security Council debate, accused Russia of launching a 'counterspace weapon' into Low earth Orbit on May 16. The claim was later repeated, including a mention of it being in "the same orbit" as a US Government satellite, by Pentagon spokesman Brig. General Pat Ryder.

This clearly refers to Kosmos 2576 (object A) - the US military evidently also thinks the co-orbital character of Kosmos 2576 with USA 314 is no coincidence. 

Russia flatly dismisses the suggestion, calling it "fake news".

Currently, there are two Russian satellites in LEO that are suspiciously co-planar with an American KH-11 ADVANCED CRYSTAL electro-optical reconnaissance satellite: Kosmos 2558 (2022-089A) co-planar with USA 326 (2022-009A); and now Kosmos 2576 (2024-092A) co-planar with USA 314 (2021-032A). Kosmos 2558 currently makes approaches to ~50 km to USA 326 each 7 days.

click image to enlarge

For those who want to compare, here are two recent orbits for USA 314 and USA 326 based on amateur tracking data:

USA 314
1 48247U 21032A   24141.96990730 0.00002000  00000-0  27073-3 0    05
2 48247  98.0438 254.1015 0157205 111.3087 248.6912 14.70745533    09
USA 326
1 51445U 22009A   24141.98253796 0.00017500  00000-0  79138-3 0    00
2 51445  97.4250 239.7279 0011614 145.1315 214.8683 15.20909891    06

Upcoming test of a Conventional Prompt Strike (CPS) hypersonic missile

click map to enlarge

A Navigational Warning has appeared that points to a US missile test conducted west of Hawaii in the period May 23 - 25, 2024, 21:30-0300 UTC. 

The shape of the hazard zones is similar to that of the (failed) June 2022 JFC-1 Conventional Prompt Strike (CPS) test, which is part of a US Navy program for a submarine-launched MRBM with a hypersonic glider as reentry vehicle. The program has ties with the US Army LHRW hypersonic missile program discussed on this blog a few times.

The range indicated by this test is about 3500 km.

The Navigational Warning (also issued as NAVAREA XII 358/24):

281825Z APR 24
HYDROPAC 1689/24(19,81).
NORTH PACIFIC.
HAWAII.
DNC 12, DNC 13.
1. MISSILE OPERATIONS 2130Z T0 0300Z DAILY
   23 THRU 25 MAY IN AREAS BOUND BY:
   A. 23-00.00N 180-00.00E, 23-00.00N 175-00.00E,
      23-00.00N 170-00.00E, 23-45.00N 165-00.00E,
      22-30.00N 165-00.00E, 21-30.00N 170-00.00E,
      20-45.00N 175-00.00E, 20-00.00N 180-00.00E.
   B. 22-01.00N 159-47.00W, 22-03.00N 159-45.00W,
      22-04.00N 159-45.00W, 22-30.00N 160-00.00W,
      22-45.00N 161-00.00W, 23-00.00N 165-00.00W,
      23-45.00N 170-00.00W, 23-45.00N 175-00.00W,
      23-00.00N 180-00.00W, 20-00.00N 180-00.00W,
      20-00.00N 174-00.00W, 20-45.00N 170-00.00W,
      21-15.00N 165-00.00W, 21-30.00N 161-00.00W,
      21-51.00N 160-00.00W.
2. CANCEL THIS MSG 260400Z MAY 24.

Launch is probably from a TEL located at the Pacific Missile Range Facility at Barking Sands, Kauai.