Friday 28 June 2024

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.

Sunday 23 June 2024

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.

Wednesday 12 June 2024

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.