North Korea has launched Kwangmyŏngsŏng 4

Launch of KMS-4 (still from N-Korean tv announcement)

My previous blogpost of Feb 4 (with an update on Feb 5) discussed the announced launch of a new North Korean satellite, Kwangmyŏngsŏng-4 (KMS-4), from Sohae satellite Launch center in the northwest of North Korea.

Yesterday (Feb 6), North Korea suddenly shifted the start of the launch window one day forward, from February 8 to February 7 (local date). No reason was given for this date shift.

The actual launch happened this morning at 00:29 UT (February 7, 2016), according to USSTRATCOM.

It appears to have been successful, to the extend that  they did successfully put an object into orbit, as the US military tracking network confirms. As the history with KMS 3-2 shows, whether the payload is really operational is another question and as for yet unanswered.

North Korean television announced the successful launch a few hours ago, in a bulletin in characteristic fashion, including images of the launch and of Kim Jong-Un watching the launch from Sohae:

Launch time

The launch time prediction of my previous post (and in this seesat list post) turns out to have been correct.

I indicated a launch between 00:24 and 00:41 UT (a 17 minute period out of a 5 hour window indicated by the North Koreans). The start of this window at 00:24 UT was based on the assumption of a launch at a similar solar elevation at Pyongyang as during the 2012 launch of KMS 3-2 (the end at 00:41 UT was based assuming a launch exactly 5 2 hours after Pyongyang sunrise rather than at a similar solar elevation to 2012).

The actual launch occurred at 00:29 UT, only a few minutes from the start of the window which I indicated. It corresponds to a solar elevation of 18.0 degrees at Pyongyang (the 2012 launch happened at a solar elevation of 17.5 degrees).


Orbit

The first orbital elements from JSpOC show two objects in orbit as a result of the launch: an A-object (catalogue number 41332, 2016-009A) and a B-object (catalogue number 41333, 2016-009B). The A-object is likely the satellite.

The A-object moves in  a 97.5 degree inclined, 465 x 502 km sun-synchronous polar orbit with an orbital period of 94.3 minutes. The satellite makes daily morning passes around ~9h am. It has a repeating ground-track every 4th day. This is consistent with a remote-sensing role.

The orbit is somewhat lower and  more circular than that of North Korea's previous satellite, KMS 3-2, which was initially placed in a 495 x 588 km orbit. Like the 2012 launch, North Korea had to perform a dogleg manoeuvre to attain an orbital inclination of 97.5 degrees after launching due south from Sohae (see discussion in my previous post).

The second, B object is the spent upper stage of the rocket, and is moving in a 433 x 502 km orbit.

The map below shows the satellite's ground-track during the first 5 orbits after launch:

North Korea's ruler Kim Jong-Un watched the launch from the grounds of the Sohae Satellite Launch Center. In the image below, he is observing the rocket ascend from a viewing platform which appears to be in front of the oval building that was erected at Sohae between March and July 2014 (see this satellite photo analysis on the 38 North blog).

A few more stills of the launch, taken from the North Korean tv broadcast:

The launch of Kwangmyŏngsŏng 4 is the second time that the North Korean rocket program was successful in placing an object in orbit. North Korea itself claims a number more successful launches, but these failed according to western sources as no objects were tracked in orbit.

Current spatial separation of the orbital planes of KMS 3-2 and KMS 4

Note added 18:00 UT, 7 Feb: a brief update noting inconsistencies between early western tracking data and a DPRK announcement is here.

[UPDATED] North Korea's upcoming satellite launch

North Korea's previous satellite, Kwangmyŏngsŏng 3-2, imaged in 2015
(click image to enlarge)

On February 8th, 2016, it will be the 70th anniversary of the formation of the Provisional People's Committee for North Korea by Kim Il-Sung, effectively marking the birth of the nation. And 16 February 2016 will be the 74th (actually 75th) birthday of the late Kim Jong-Il, while in addition February 14th is a day that commemorates Kim Jong-Il assuming the role of "Grand General of the DPRK". Such dates often see some significant national posturing of North Korea.

Following a nuclear test on January 6th (claimed to be a small H-bomb by the North Koreans, although western observers doubt this), North Korea has announced the launch of a satellite, with issued Broadcast Warnings pointing to a launch between February 8 and 25. The launch period starts at the date of the 70th anniversary of the Provisional People's Committee.  

Satellite image analysts at the 38 North website had already been documenting preparations for a launch at the launch site in Sohae in January. Over the past 3 year, North Korea had been making several improvements to its launch installations, building various new structures on the site.

Meanwhile, the upcoming launch has western nations and neighbouring states concerned. Especially Japan has expressed very strong concerns about the launch. Like they did in 2012, they have threathened to shoot the rocket down if it seems to be headed for Japan. That is unlikely to happen though.

The Broadcast Navigational Warnings issued delineate three splash-down areas of rocket debris:

HYDROPAC 294/16
WESTERN NORTH PACIFIC.
YELLOW SEA.
EAST CHINA SEA.
PHILIPPINE SEA.
ROCKETS.
DNC 23.
1. HAZARDOUS OPERATIONS 2230Z TO 0330Z COMMENCING
   DAILY 07 THRU 24 FEB IN AREAS:
   A. BETWEEN 35-19N 36-04N AND 124-30E 124-54E.
   B. BOUND BY
      33-16N 124-11E, 32-22N 124-11E,
      32-21N 125-08E, 33-16N 125-09E.
   C. BOUND BY
      19-44N 123-53E, 17-01N 123-52E,
      17-00N 124-48E, 19-43N 124-51E.
2. CANCEL THIS MSG 250430Z FEB 16.

[added note: the original letter of North Korea to the Int. Maritime Organization on which this navigational warning is based, is here].

Area A is the splash-down area for the first stage, area B for the fairings, and area C for the second stage (the third stage will remain on-orbit after launch). Plotting these on a map (red boxes in map below) reveals them to be on a north-south line with azimuth ~180 degrees (yellow line), avoiding the main islands of Japan:

(click map to enlarge)

The ~180 degree launch azimuth points to a satellite launch into Polar orbit, very similar to the launch direction of North Korea's previous satellite, Kwangmyŏngsŏng (KMS) 3-2 (2012-072A) three years ago (a nice background piece on that launch by Brian Weeden discussing "satellite launch or missile test?" can be found here). Compare my map above to the map constructed from the NOTAM's for the KMS 3-2 launch in 2012 on Bob Christy's website, [edit: and see also the comparison of 2012 to 2016 in this blogpost by Melissa Hanham on the Arms Control Wonk blog].

As was the case with their previous KMS 3-2 launch, the intended satellite orbit is, given the launch direction, likely a sun-synchronous orbit with an orbital inclination of 97 degrees. The launch direction due south rather than directly into a ~97 degree inclined orbit has been chosen to avoid overflying (and debris landing on) the territories of China and Taiwan during the ascend phase. In order to reach a true sun-synchronous orbit with inclination ~97 degrees, it necessitates a dog-leg manoeuvre of the third stage with payload during the final phase of the ascend to orbit (blue line in map above, approximate only). Orbit insertion of the payload will be about ten minutes after launch, just before reaching the Phillipines.

Assuming the resulting orbit of the satellite will be similar to that of KMS 3-2 in 2012 (perigee ~495 km, apogee ~588 km, inclination 97.4 degrees), the trajectory of its first revolution around earth will look something like this (yellow dot shows satellite position one hour after orbit insertion):

(click map to enlarge)

The launch window is 17 days long, and runs daily from 22:30 to 03:30 UT, according to the Broadcast Warning. The daily 22:30-03:30 UT window is similar to that of the KMS 3-2 launch in 2012. It runs from local daybreak to just short of local noon, indicating a desire for an orbital plane resulting in morning passes.

[edit: the paragraph below was slightly editted on 5 Feb 2016, expanding the discussion of possible launch times]

In 2012, KMS 3-2 was launched at 00:49:49 UT, almost exactly two hours after Pyongyang sunrise (22:50 UT). This suggests (if a similar orbital plane with overfly times at ~9h am local time is aimed for) that the current launch might happen somewhere between 00:24-00:41 UT, depending on whether the aim is for launch at a similar solar elevation (then it will be close to 00:24 UT) or merely two hours after Pyongyang sunrise (then it will be close to 00:41 UT). However (see the next paragraph), the timing of the 2012 launch also seems to have been (at least partially) dictated by a suitable window lacking overflights by western reconnaissance satellites. As for the date, I hesitate to prophecy on this, but I wouldn't be surprised if they go - weather permitting- for February 8, the first day in the 17-day window.

It appears that the North Koreans carefully chose their launch moment in 2012. US military sources already had claimed shortly after the launch that North Korea had played a ruse on them and evidently knew when western optical imaging satellites had (and had not had) view of the launch installations. This seems to be confirmed by my independent analysis of that launch from December 2012, which showed that the North Koreans used the very end of a longer-than-usual one-hour gap in IMINT coverage of the launch site to launch. And as I wrote in that blog post, a North Korean IP address had been looking for orbital elements of  US optical and radar satellites on this very blog just days before the launch.

The ruse was apparently designed to keep the USA, Japan and South Korea in the dark about the launch moment until the actual moment of launch itself (which would be registered by SBIRS and DSP satellites), as a counter-measure to give potential intercepts of the rocket as little advance preparation time as possible.

It would be difficult for North Korea to repeat such a ruse these days, as the number of western optical and radar reconnaissance satellites has grown ubiquitously in the past three years. Assuming launch near 00:40 UT (two hours after sunrise), the most promising dates (from the perspective of relative lack of western IMINT coverage) are three dates in the first week of the launch window:  February 8, 10 and 14. But maybe North Korea is confident enough this time, following the experience with KMS 3-2, to not bother with western IMINT coverage at all.

[UPDATED] Imaging North-Korea's Kwangmyŏngsŏng-3 (KMS 3-2) satellite

Kwangmyŏngsŏng-3 (KMS 3-2) passing Deneb, evening of 10 Oct 2015
click image to enlarge

UPDATE (11 Oct 2015):
I imaged Kwangmyŏngsŏng-3 again the next evening (image above), 10 Oct 2015 near 18:32 UT, when it passed the bright star Deneb (brightest star in image). This time I used the Zeiss Sonnar MC 2.8/180mm lens, which shows fainter objects but has an even smaller FOV. The trail is faint but shows up well (click the image to enlarge).

Kwangmyŏngsŏng-3 (KMS 3-2), evening of 9 Oct 2015
click image to enlarge

[original post before update:] Yesterday evening started clear. While my targets for that evening were the payloads of the NROL-55 launch from October 8 (more on that in a later post), I took the opportunity to image a pass of North-Korea's satellite Kwangmyŏngsŏng-3 (KMS 3-2) in the early part of the evening. The image above shows it, as a very faint trail.

Kwangmyŏngsŏng-3 (2012-072A) makes favourable passes in early autumn and in spring. In October it is making evening passes. Yesterday I had a very good illuminated pass near 20:50 local time (18:50 UT).

By coincidence my imaging of KMS 3-2 yesterday happened on the eve of the 70th anniversary of the Worker’s Party of Korea. There were rumours of a pending new N-Korean satellite launch, perhaps with a stronger rocket, on or near that date, although at least one assessment of satellite imagery by the 38 North blog, suggests the new launch platform at Sohae, which North-Korea has been building the past year, is far from ready yet.

KMS 3-2 is a difficult object to photograph, as it is very faint: it is a cube of only about 1.0 x 0.75 meter in size. It is also tumbling. This makes it a challenge: it is in a Low Earth Orbit and moving relatively fast, but a  lens which is fast enough to capture it during it's brief brightness peaks has a limited FOV. In practise, my f1.4/85mm lens can just show it during the brightest part of it's periodic brightness variability, but it is a gamble whether that happens in the FOV or not. So far I had managed to image it once before, a year ago.

Yesterday evening, I was lucky again: during a nice high late twilight pass with the the satellite culminating at an elevation of 60 degrees in the W-SW, it did reach peak brightness in the FOV of my lens, resulting in four images showing it. The best of these is shown above.

click image to enlarge

Kwangmyŏngsŏng-3 was launched three years ago, on 12 December 2012. It was the first successful launch by North-Korea, in the sense that the payload reached orbit. Whether the payload is operational (as PyongYang claimed), is another question. It's brightness behaviour shows it is tumbling, which is something an operational Earth Reconnaissance satellite should not do.

At the time, I did an analysis of the launch-window. It appeared to have been very carefully choosen to avoid coverage of the launch site (and specifically last-minute launch preparations) by Western reconnaissance satellites in the hour before the launch. Interestingly, North-Korea tried to find orbital elements for such Western reconnaissance satellites by looking on this very weblog.

Imaging the North Korean Kwangmyŏngsŏng (KMS) 3-2 satellite

Yesterday evening was initially clear. Using the SamYang 1.4/85 mm lens, I imaged an object that has been on my "to do"-list for a (too) long time: the North Korean satellite Kwangmyŏngsŏng 3-2 (KMS 3-2, 2012-072A), visible as a very faint trail on this image:

click image to enlarge

Kwangmyŏngsŏng ("Brilliant Star") 3-2 was launched under much international tension almost two years ago, on 12 December 2012, from Songhae. It is the first and so far only successful North Korean launch.

On 8 Dec 2012, just days before they launched KMS 3-2, the N-Koreans actually visited this weblog, looking for information on US IMINT satellites (specifically Lacrosse and Keyhole). As I wrote at that time, very few North-Koreans have access to the internet. Those who do, have close ties to Kim Jung Un or are among the top military. So that visit was surprising.

The reason became quickly apparent. Post-launch, I made an analysis of the KMS 3-2 launch time, showing that the North Koreans picked a carefully determined one-hour gap in Western space-based IMINT coverage to launch their satellite.

Later that month, on 21, 22 and 23 Dec 2012, the North-Koreans popped up again, visiting my launch time analysis post, and searching for TLE's of their own satellite! (one would expect that the Chinese could provide these to them, so this was surprising again). The visits came from another IP than the Dec 8 visits.

Another visit to this blog was made two weeks later, on 8 Jan 2013, from the same IP as the Dec 8 visit (but another computer perhaps, as the Dec 8 visitor used Windows Xp, but this visitor Windows 7). This time the subject of the visit was my analysis of the tumbling behaviour of the satellite which I made late December 2012 using Greg Roberts' 20 Dec 2012 footage of a KMS 3-2 pass (as it was in the dead of the Northern hemisphere winter, it was not possible for me to image the satellite myself at that time). They might have been interested in my analysis in order to assess the character of this tumbling, which was probably not intended and might indicate a failure to stabilize the satellite after orbit insertion.

Then it was quiet for 1.5 years. But last summer, I got another surprise N-Korean visit to this blog. This happened on June 9, and it was this visit which reminded me that it might be fun to try to image the satellite this summer. For various reasons, I only succeeded last night.

The June 9 N-Korean visitor visited posts about the SDS and SBSS satellite systems. The first (SDS, Satellite Data System) is a system of geostationary US military data relay satellites which (a.o.) relays IMINT data from other satellites to the US. The other (SBSS, the Space Based Space Surveillance system) is a satellite in Low Earth Orbit for detecting and tracking objects orbiting in space (i.e., other satellites - like those of North Korea).

This visit came while upgrade activities of the launch installations at Sohae were documented by the 38 North blog. The upgrade seems to point to Sohae being readied to facilitate a heavier launch vehicle. How a North-Korean interest in SBSS and SDS would fit into this picture, is however not entirely clear, apart from that it could indicate that they might aim to avoid SBSS tracking of their payloads during the initial orbit insertion.

The flashing behaviour of North Korea's tumbling Kwangmyongsong 3-2 satellite

North Korea's first satellite Kwangmyongsong 3-2 (KMS 3-2) cannot be seen from the northern hemisphere at the moment (and hence cannot be observed by me currently). On the southern hemisphere, Greg Roberts (CoSatTrak) in South Africa is however successfully tracking the satellite.

He had a particular good pass on December 20th and obtained a very nice video record, tracking on the satellite with a motorized mount (note: movie has a period of black screen between opening title and start of the video record):

Greg Robert's video from S-Africa

(posted with permission)

The satellite is the object near the center of the screen, flashing about each 8.5 seconds with periods of invisibility inbetween. The moving streaks are stars (the mount is tracking the satellite as it moved along the sky): the other stationary dots in the image are hot pixels on the sensor of the video camera.

The video allows for an analysis of the flashing behaviour of the satellite. I used LiMovie to measure the satellites' brightness on the frames, resulting in the following lightcurve:

click diagram to enlarge

Visible is a clear ~8.45s periodicity with flashes of a specular character (suggesting a flat reflective surface). I have marked this with red triangles 8.45 seconds apart. In between the main flashes, a pattern of smaller secondary flashes can be discerned in a semi 8.45 second peridicity too (green triangles). They are not exactly positioned halfway between major flashes.

Assuming that each major flash is a flash caused by one of the sides of the KMS 3-2 cube-shaped body, then it completes a tumble once every ~33.8 seconds. Assuming that the less clear secondary flashes are due to a side of the cube as well, the tumbling periodicity would be half of that, i.e. 16.9 seconds.

Greg recorded the UNHA-3 r/b from the launch too. That one too is tumbling:

Greg Robert's video from S-Africa

(posted with permission)

Again, I used LiMovie to extract brightness information from each video frame. That was less successful with this video, because Greg's mount had difficulty keeping up with the fast-moving r/b for much of the record. A considerable part of the video could not be used for analysis, and I had to chop up the analysis in little non-continuous chunks:

click diagram to enlarge

What can be seen, is a flashing behaviour that starts slow and gentle and is increasing in rapidity near the end of the analysis, this being an effect of changing viewing angle.

Contrary to what some alarmist (sometimes almost hysterical) media reports have suggested, the tumbling of KMS 3-2 is by no means dangerous. David Wright over at All Things Nuclear has a very good debunking story about this all, pointing out the many misconceptions rampant in the reporting.

[UPDATED] A post-analysis of the N-Korean launch window, and N-Korean Spooks on my weblog?

On December 12, North Korea surprised the Western world by successfully bringing its first independently confirmed satellite into orbit: Kwangmyongsong 3-2, a reportedly 100 kg cubesat. For images of the satellite and an analysis of its likely components, see here. The satellite was launched with an UNHA 3 rocket from Sohae Launch Centre in Cholsan.

The successful launch came as a surprise for two reasons. First, all previous North Korean satellite launch attempts abysmally failed (even if N-Korea claimed they were a success).

Second, North Korea had indicated days before the launch that the launch was to be postponed to late December, for technical reasons. This appears to have been a deliberate disinformation ploy by N-Korea. According to South Korean press sources, it appears they also tried to play a ruse on the Americans, by pretending to dismantle the rocket when US imaging satellites were overhead, and continuing launch preparations when they were not.




Analysing the time of launch and US satellite coverage of the launch site

Well then: did the North Koreans indeed try to evade US (and Japanese) satellite surveillance?

First, they would not have been able to evade detection of the launch itself by US infra-red early warning satellites such as the DSP satellites and SBIRS in geostationary and HEO orbit. Coverage by these satellites is continuous.

But that was probably not N-Korea's goal anyway. Their goal reportedly was to try to convince analysts of imagery from US imaging satellites (optical and radar) that the rocket was not yet complete at the launch site, and not yet ready to launch for a while. The aim was apparently to throw off US predictions about the "when" of the launch until the very moment of launch itself.

Their concern hence was with US and Japanese optical and radar imaging satellites such as the KH-12 Keyholes, Lacrosses, FIA and IGS. These imaging satellites move in LEO, and coverage is not continuous- not yet at least.

Indeed, the timing of the North Korean launch (00:49 UTC on December 12) is interesting. It coincides with the end of a one hour long interval with no coverage of the launch site by US or Japanese Low Earth Orbit imaging satellites.

By contrast, in the hours prior to and after this one-hour gap in coverage, such periods of non-coverage were much shorter (typically 10-15 minutes at best), as can be seen in the coverage analysis images below and the movie near the top of this post (movie, images and analysis made using JSatTrak).

click image to enlarge

As can be seen from the coverage analysis, this hour long interval between 23:45-00:45 UT really stands out compared to the hours before and after. The N-Koreans launched right at the end of this interval at 00:49 UT, just when the launch site was coming into reach of the FIA Radar 2.

I feel the launch right at the end of this interval is no coincidence: they picked a moment where prior to launch they would have a substantial gap in US satellite surveillance available to complete their launch preparations. The one-hour long interval seems to have provided the North Koreans enough time to remount whatever they dismounted or camouflaged as a ruse, and launch.

(some remarks on the analysis and movie above: for a few of the satellites shown, positions are not 100% certain. For example, the Keyhole USA 186 hasn't been observed for a while because of the midwinter blackout. Satellites included in the analysis are the Japanese IGS, the US Keyholes, Lacrosses and FIA [edit: plus SPOT, Worldview and Quickbird commercial imaging satellites]).

Update 17/12 12:45 UT: 
I initially forgot to include the GeoEye Worldview and Quickbird commercial imaging satellites in the analysis. These commercial sats are frequently hired by the US government for selected imaging and used by independent analysts as well.

I have now added these satellites to the analysis, and the one-hour gap coverage between 11 Dec 23:45 and 12 Dec 00:45 UT keeps standing:

click image to enlarge

Update 17/12 16:00 UT:
Also added the French SPOT satellites to the analysis. Again, the 1-hour coverage gap between 11 Dec 23:45 and 12 dec 00:45 UT keeps standing.

Korean Spooks on my weblog?

There is a bizarre twist to this all that involves this weblog. In the late morning of December 8th, four days before the launch, an IP solving to North Korea visited this weblog. It entered through web-searches that included the keywords 'tle', 'KH-12' and 'Lacrosse 5'. A screenshot of the web statistics is below:

click image to enlarge

North Koreans with access to international websites are about as rare as, well, North Korean unicorns. Only a very select handful of North Koreans -mostly direct family members of Kim Jong Un- are allowed access to the internet.

Disclaimer: I was (and am) slightly suspicious. IP's can be spoofed, and two things caught my eye. One is the OS listed, Windows Xp. N-Korea is supposed to have its own OS, 'Red Star'. But then, maybe they only use this for their own, completely internal version of the internet. Or maybe western webstatistics providers cannot properly recognize it and list it as Xp (plus it could be a knock-off of Xp, even).

Second initially suspicious detail: the 10:05 and 10:07 visits have the word "satelliet", not "satellite" in the search string. That raised some suspicion as "satelliet" is the Dutch word for "satellite". However: that could also be a simple typo (switching the last two characters - a very common kind of typo) instead of a Dutchman typing.

Assuming that this was a real N-Korean visit, then the visit is highly interesting with reference to the apparent ruse played on US satellite surveillance of N-Korea as analysed above.

For here we apparently have a North Korean, a country where the average Kim is not allowed access to the internet, looking for orbital information on US surveillance satellites on my weblog!

This moreover was someone with at least some knowledge of satellites - again, not your average North Korean Kim, but suggestive of someone from the NK space program or intelligence program. The specific keywords 'tle' (two-line elements, i.e. a set of satellite orbital elements) and 'Lacrosse 5' (a US radar imaging satellite) and 'KH-12' (US Keyhole-12/Advanced Crystal optical imaging satellites, i.e. the satellites USA 129, USA 161, USA 186 and USA 224) bear this out.

Yet this person wasn't perhaps entirely informed. He or she searched for orbital information on those US optical and radar imaging satellites that form the backbone of US space-based surveillance, but notably missing from the search queries is the most recent addition to the US radar surveillance constellation, the two FIA Radar satellites. Also missing are Japan's IGS satellites. But, maybe, after checking for the KH-12 and Lacrosse 5 they realized they should not be on my blog for this information - they should be at Mike's website for that.