Wednesday, 4 October 2017

The Space Age turns 60

click to enlarge
Today at 19:28:24 UT, it is exactly 60 years ago that Sputnik 1, the first artificial satellite of the Earth, was launched from Tyuratam (Baikonur) in the Soviet Union. Thus, the Space Age was born.

Sputnik 1 would stay in orbit for  four months and then re-entered into the atmosphere. The image above shows the very first two orbits (and is based on a TLE from the website of Jonathan McDowell. Strictly speaking, this TLE is for the upper stage of the rocket, but during the first few orbits the orbits of both objects were very similar).

Monday, 2 October 2017

The North Korean Hwasong-12 test of 14 September: georeferencing Kim Jong Un's map

(This post has been a while in the making. Due to various reasons, including the 21 Sept fireball, I did not come to write it up on this blog until now. The same analysis however was earlier presented as a Twitter-thread, on 23 September)

"I love the smell of UDMH in the morning..." (photo: KCNA)

Over the past months, I have spent a number of posts on North Korea's recent increasingly bold missile tests. The latest of these tests happened on September 14 (local September 15 in North Korea). At 21:57 UT that day, North Korea launched a Hwasong-12 IRBM from Pyongyang Sunan airfield towards the east-northeast. It crossed over Japan (causing air-raid alarms to go off) with, according to western military sources, a range of ~3700 km and apogee at 770 km, before impacting in the Pacific Ocean. The test was the second one to launch the Hwasong in a 'regular' rather than 'lofted' trajectory, over Japan.

I was abroad at the time of the test,  meaning it was several days before I could look at this test and start an analysis. Some results were earlier presented on 23 September as a Twitter-thread.

photo: KCNA

As part of the propaganda photographs published by KCNA following the test, there was (just like after the test of 29 August) a picture of Kim Jong Un sitting behind a desk, with a map in front of him. As was the case for August 29, the map shows a missile trajectory, presumably the trajectory aimed for in this test:

photo: KCNA

I obtained a high resolution version of this photograph for analysis with the much appreciated help of Ankit Panda. First, I roughly squared this image using the skew-tools in Photoshop:




Next, I georeferenced this image against an actual map using QGIS. The resulting map is the one below (the map projection I have used is a Lambert azimuthal equal area projection centered on Sunan. The grid is WGS84). :


click map to enlarge

The result of this georefencing is that the drawn trajectory starting at Sunan ends at approximately 39.60 N, 168.05 E. The range from Sunan to this impact location is 3615 km.

Note that I have added, in yellow, country outlines to the map to show the validity of the georeferencing. I also added a few annotations. I have added an STK-modelled ballistic trajectory to the map as a dashed red line: it is highly similar to the original trajectory line drawn on the map, as you can see, with apogee position corresponding to what appears to be a text in red on the map: what was depicted on Kim Jong Un's map hence appears to be a real ballistic trajectory.

The resulting range of 3615 km is close enough to the range reported by Western military sources (about 3700 km) to conclude that the 14 September test went much as intended.

This is a difference with the 29 August test. In that case, the map showed a ~3300 km range while western military sources said the actual range flown was ~2700 km: it also flew more north than the trajectory that was depicted on the 29 August map. See my earlier blog post here. The match for the 14 September test might indicate that the 29 August test perhaps did not go as intended.

The map below shows both trajectories: that of 29 August as depicted on Kim Jong Un's map (i.e. not the actually flown trajectory!), and that of 14 September as depicted on Kim Jong Un's map:

click map to enlarge (map by author)

It is interesting to look at the range distances for both tests. The range distances of 3316 km and 3615 km ring a bell. The distance from Pyongyang Sunan (the launch location) to Henderson AFB on Guam is ~3415 km. The August 29 map trajectory falls almost exactly 100 km short of that range, while the September 14 trajectory almost exactly 200 km overshoots this range.

I am going back-and-forth on whether this is significant or not. I tend to think that all these kind of map images released are intentional propaganda meant to convey a message: the map is meant to be analysed and "read" by the West.

As an illustration of how it potentially could be read: would we change the launch directions so that they would be towards Guam, then this (the two black crosses) would be the result in terms of the pattern of impact locations relative to Guam:

Remember that North Korea has "threathened" to conduct a quadruple demonstration with four missiles impacting in international waters in an 'envelope' around Guam, if the Trump administration does not stop B1 bomber demonstration flights from Guam. Do we see some kind of test mock enactment for this here? Is the message: "We are already practising for this, imperialist barking dottard dog!".

It would become very interesting if North Korea were to launche two other missiles the coming month, and the pattern where they (were implied to) land relative to the earlier two tests might be very interesting.

photo: KCNA
(I thank Ankit Panda for his help with obtaining a high resolution version of the photograph with Kim Jong Un and the map)

Tuesday, 26 September 2017

OT: The brilliant fireball over the Netherlands of 21 September 2017, 19:00 UT, a piece of comet Encke

The fireball as photographed from Ermelo, the Netherlands. Image (c) Koen Miskotte


In the evening of 21 September 2017 at 21:00:10 CEST (19:00:10 UT), a brilliant fireball, as bright as the first quarter moon, appeared over the Netherlands. It was widely seen and reported and garnered quite some social media and press attention (e.g. here). The next day I was live in a Dutch TV program to talk about it.

The fireball was captured by six all-sky camera stations of the Dutch-Belgian all-sky meteor camera network operated by amateurs of the Dutch Meteor Society and KNVWS Meteor Section: stations Ermelo, Oostkapelle, Borne, Utrecht, Twisk and Wilderen, operated by respectively Koen Miskotte, Klaas Jobse, Peter van Leuteren, Felix Bettonvil, Marco Verstraaten and Jean-Marie Biets.

The image in the top of this post shows the photograph taken by the all-sky camera in Ermelo (courtesy Koen Miskotte), where the fireball appeared almost right overhead. The image below was taken by the all-sky camera in Utrecht (courtesy Felix Bettonvil), showing it slightly lower in the sky (click the images to enlarge).


The fireball as photographed from Utrecht, the Netherlands. Image (c) Felix Bettonvil

In the photographs above, the "dashed" appearance of the fireball trail is caused by an LCD shutter between the lens and the camera CCD, which briefly interupts the image at a set interval. For Ermelo this was 14 interuptions per second, for Utrecht 10 interuptions per second.

Knowing the shutter frequency you get the duration of the fireball by counting the number of shutter breaks in the trail: in the case of this fireball, it lasted over 5.3 seconds. Together with triangulation information on the path of the trail in the atmosphere, it gives you the speed of the fireball in km/s, which is necessary to calculate the orbit in the solar system. It also provides you with information about the deceleration of the meteoroid in the atmosphere. In this case, it entered the atmosphere with a speed of 31 km/s and by the time it had completely burned up at 53 km altitude, the speed had decelerated to 23 km/s.

The fireball fragmented into pieces quite early during its atmospheric entry. Some of these fragmentation events can be seen as brief brightenings (flares) in the images.

Triangulation of the six all-sky images yields the following atmospheric trajectory:

Atmospheric trajectory of the fireball, calculated by the author. Camera stations in yellow.

The  fireball moved almost due east-west. It started over Deventer, crossed over southern Amsterdam and Schiphol airport, and ended over sea. The end altitude at 53 km and end speed of 23 km/s indicate that nothing was left of the original meteoroid by the time the fireball extinguished: no meteorites reached earth surface, it completely ablated away.

The apparent radiant of the fireball was located low in the sky, at 16 degrees elevation and almost due east. The grazing entry into the atmosphere resulted in a long trajectory length of over 150 km.

The geocentric radiant of the fireball is located on the Pegasus-Pisces border, just north of the ecliptic. The radiant and speed, and the resulting orbit in the solar system, show that this was an early member of the northern branch of the Taurid stream complex, a meteor stream complex associated with comet P/Encke. It is active from September to December with a  peak in activity in November. The stream is broken up in several substreams, and the early Northern Taurids from September are sometimes called Northern delta Piscids, one of these substreams in the Taurid complex.

The radiant position and heliocentric orbit for this fireball are shown below.

apparent (observed) and geocentric radiant of the fireball

calculated heliocentric orbit of the meteoroid


Acknowledgement: I thank the photographers (Koen Miskotte, Klaas Jobse, Peter van Leuteren, Felix Bettonvil, Marco Verstraaten and Jean-Marie Biets) for providing their imagery for this analysis.

Monday, 4 September 2017

OT: imaging the close flyby of Amor asteroid (3122) Florence



On 1 September 2017 near 12:06 UT the Amor class Near Earth Asteroid (3122) Florence made a relatively close approach to Earth. The nominal pass distance, 0.047 AU or about 18 Lunar distances, was a safe distance. It does not often come this close: the asteroid had last been about similarly close in 1930, and will not be really close again until 2057.

(3122) Florence is one of the more rare larger NEA's. It is about 5 km in diameter and currently has a theoretical MOID (Minimum Orbit Intersection Distance) of 0.044 AU, only slightly less than the pass this year.

While this is a safe distance for now, orbital disturbances in the (distant) future could bring it closer, and the size of the object is such that it would be of future impact concern. It is therefore on the PHA list, where PHA stand for "Potentially Hazardous Asteroid" (for some reason, I always make "Potentially Hostile Asteroid" of this in my mind, probably because of the similar "Potentially Hostile Aircraft").

(3122) Florence became quite bright during this close pass, and was visible in binoculars at a maximum brightness of about magnitude +8.7 just before the moment of closest approach.

About 1.5 days after the moment of closest approach, near local midnight of September 2-3, I imaged the fast moving asteroid from Leiden with my Celestron C6 telescope. It was about mag +9.1 at that time. The movie above, and the stacked image below, was made from 87 images (each an exposure of 10 seconds with a 5 second interval) taken over a 17-minute period between 22:31:32 - 22:48:47 UT (Sep 2).

The asteroid was at a distance of 0.048 AU at that time and moving fast through Delphinus, at an angular speed of about 22".5 per minute.

The equipment used was a Celestron C6 (15 cm) Schmidt Cassegrain telescope with F6.3 focal reducer, and a Canon EOS 60D DSLR at ISO 3200 in the prime focus of the telescope.

(the satellite that can also be seen zipping past in the movie, is a Russian GLONASS, Kosmos 2425)

stack of 87 images taken over a 17-minute time interval
(click image to enlarge)

Friday, 1 September 2017

The other subliminal message in Kim Jong Un's missile test map

image: KCNA
The image above (from North Korea's KCNA) shows the North Korean leader Kim Jong Un and a map. It was likely taken on the day of the 29 August missile test that shot a Hwasong-12 MRBM over Japan, into the Pacific Ocean. I analyzed this map and what it shows in detail in my previous post, showing that the trajectory which seems to be sketched on the map deviates from the real missile flight path.

But there is more to this map, it turns out after further analysis. There are not one, but two subliminal messages contained in this map.

The first subliminal message, already discussed at the end of my previous post, is that it depicts a 3300 km trajectory (the real flight trajectory appears to have been shorter, 2700 km). This is the approximate distance to Guam.

But there is a second subliminal message. The map also contains a veiled threath to Hawaii.


click to enlarge

As can be seen in the annotated georeferenced version of the map image above (see also my previous post), the trajectory skeched on the map (white) is very close in direction to what a trajectory towards Hawaii would be.

In the map above, there are two lines representing such a trajectory targetting Hawaii:

- The green dashed line shows what a real, 7400 km range trajectory towards Pearl Harbour would be (this takes earth curvature and earth rotation into account);

- The yellow dashed line shows what the trajectory is if launched into the same azimuth as for  targetting Pearl Harbour, but with a shorter 3300 km range, as on the map in front of Kim Jong Un.

The latter yellow line obviously is very close to what is sketched on Kim Jong Un's map. In fact, I think that within the error margins of my georeferencing effort, they might well be the same.

The white line, my best effort to represent the trajectory sketched on the map, would be a missile launched into azimuth ~77.25 degrees. The dashed yellow and green lines, are both for missiles fired into azimuth ~76.9 degrees. 76.9 and 77.25 degrees are very close, a difference of only ~0.35 degrees.

To clarify further what the map depicts: the reason that, even though the launch azimuth is the same, the green and yellow lines do not overlap is because of earth rotation and earth curvature. Firing a missile into the same azimuth (~76.9 degrees) from Pyongyang Sunan, yields a slightly more southern trajectory if the range of the missile is ~3300 km (as on Kim Jong Un's map) instead of ~7400 km (the distance to Pearl Harbour). This is because a flight to Pearl Harbour takes longer in time, and the earth surface is meanwhile rotating under the flight path.

So the trajectory sketched on the map contains two subliminal messages: the length (~3300 km) is roughly the distance to Guam. The launch direction is the launch direction towards Pearl Harbour. Two veiled threaths in one. No wonder Kim Jong Un smiles so exuberantly: "Riddle this, you Imperialist agressor Puppets!".

I firmly believe that the North Korean propaganda machine deliberately includes these images into what it makes public. When they show a map or monitor with a trajectory, however oblique and vague, it is not unintentional but (I firmly believe) intentional.

(this post is a follow-on to my earlier analysis here)

Thursday, 31 August 2017

North Korea's 29 August Hwasong-12 test with Japan fly-over: did it go as planned?

image: KCNA
It are hectic times for those (like this author) interested in the North Korean rocketry program. The past months have seen a steady series of increasingly bold missile tests (along with a threath of test-firing missiles towards Guam), that have been the subject of three earlier posts on this blog the past months.

And now a new one has occurred, and it is perhaps the boldest of these test flights so far. Last Thursday, 29 August 2017, at 20:57 UT, North Korea launched a Hwasong-12 MRBM on a trajectory over Japan: a politically bold move that caused air-raid sirens to go off in Northern Japan.

images: KCNA

Western military sources say that the missile was fired from Pyongyang Sunan airfield. It reportedly travelled 2700 km, crossing over Hokkaido, coming down in the Pacific Ocean about 1180 km from Cape Erimo in southeast Hokkaido, Japan. Apogee of the trajectory is quoted as 550 km.

This allows us to produce the trajectory reconstruction below (with some leeway as the quoted ranges are probably balpark figures). It shows that the missile crossed Japan over the southern tip of Hokkaido, a trajectory that seems designed to minimize Japanese landmass overflown, mitigating risk levels. The two red circles on the second map are depicting a 2700 km range around Pyongyang Sunan and 1180 km range around Cape Erimo. Where they are closest, is the resulting impact point (near 41.92 N, 157.56 E). Using STK I get a flight-time of ~14 minutes.

click to enlarge

click to enlarge
That odd-looking second of the two maps above is based on an interesting photograph published by the North Korean State News Agency KCNA. It shows an exuberant Kim Jong Un sitting on a desk with a map in front of him:
image: KCNA

We have recently seen more of this kind of shots from KCNA published after previous tests, and they often yield interesting information. In this case, the interesting detail is that a trajectory appears to be depicted on the map, as a thin line (the arc above it ending at the same point likely is a 3D representation):



If the sketched line indeed is the intended trajectory, then the interesting point of it is that it does not match the observed trajectory according to Western military sources.

I used my GIS skills to georeference the map on the image (with QGIS). Like in the case of the 'Guam map', the low resolution of the image and very oblique angle of te map on it make this a challenge, and the georeferencing obviously is not perfect - but good enough for some conclusions. This is the result (look for the vague line that possibly represents a trajectory on the image):

click to enlarge
Here is the same map but with annotations added, and with the trajectory sketched on the map (white line) and the actual observed trajectory (black dashed line):

click to enlarge

It is immediately obvious that the two trajectories do not match well. The trajectory (if it is one) sketched on the Kim Jong Un map is located more to the south, and indicates a larger range, about 3300 km (interestingly, it does conform to a real ballistic trajectory with earth rotation and curvature taken into account, unlike the straight line drawn on the infamous "Guam map").

(the second map shows exactly the same map area, but with a DEM and country shapefile as background. It shows you how the topography matches that on the georectified map from the photograph)

The difference between the two trajectories amounts to a range difference of 600 km and a 45 km difference in apogee. It represents a difference in launch azimuth of 6 degrees and of 3.7 degrees in launch elevation. It points to an underperformance of around 0.4 km/s in the missile's burnout speed.

click to enlarge
It is interesting to note that while North Korea for some previous tests (and their proposed Guam shot) published very accurate figures for range, flight time and apogee, they did not do that this time. It is also interesting to note that some Western military sources report that the missile "broke into three pieces".

So there are multiple indications that the test did perhaps not go entirely as planned, with an underperformance of the rocket engine and an error in launch direction, and perhaps structural failure. This would imply that the targetting of the Hwasong-12 is not quite fail-safe yet, which has implications for Kim Jong Un's proposed Guam enveloping missile demonstration.

This was the first test of the Hwasong-12 on a "normal" trajectory and it shows why it is important for North Korea to test its missiles on such a normal operational, rather than a 'lofted' trajectory: it is a different regime of stress on the missile and has the engines perform under more realistic conditions than on a 'lofted' trajectory. Errors in targetting and missile performance become more apparent.

For North Korea to do such tests on a "normal" trajectory for its MRBM's and ICBM's, they have to fly it over Japan. We are going to see more of this kind of tests the coming months is my prediction.


Update 31 Aug 2017:

(1) The 38 North blog has an interesting post suggesting the possible failure of a post-boost vehicle.
(2) South Korean and US military analysts appear to come to the same analytical conclusions as I did, according to this Korean news bulletin
(3) As Ankit Panda rightfully remarked, the situation drawn on Kim Jong Un's map need not comply to reality. It could be merely meant as a propaganda message (3300 km is roughly the distance from the launch site to Guam).

Update 1 Sep 2017:

A further follow-on post is here, discussing how the map contains two veiled threaths, to Guam and to Pearl Harbour.

Sunday, 13 August 2017

[UPDATED] My take on North Korea's hypothetical threath to Guam

click to enlarge

The sabre rattling between North Korea and the United States is continuing, with increasingly colourful and volatile language and threaths from both sides.

In response to Trumps statements on August 8 that North Korea better stop its threaths or else "they will be met with fire and fury like the world has never seen", the North Korean General Kim Rak Gyom, commander of the Strategic Force of the Korean People's Army, released a  statement through KCNA on August 10 that included a surprisingly detailed threath about firing four Hwasong-12 missiles towards the US island (and important Pacific Naval and Air Base) of Guam.

Two relevant parts of the statement read (emphasis added):

As already clarified, the Strategic Force of the KPA is seriously examining the plan for an enveloping strike at Guam through simultaneous fire of four Hwasong-12 intermediate-range strategic ballistic rockets in order to interdict the enemy forces on major military bases on Guam and to signal a crucial warning to the U.S.
 [...]
The Hwasong-12 rockets to be launched by the KPA will cross the sky above Shimane, Hiroshima and Kochi Prefectures of Japan. They will fly 3 356.7 km for 1 065 seconds and hit the waters 30 to 40 km away from Guam.

The details listed, allow to reconstruct the intended launch site for this scenario. It points to launch of the missiles in the vicinity of Sinpo, an important North Korean Naval Base that is home to its experimental SLBM force and according to satellite imagery analysts has recently seen "high levels of activity" (although that is not necessarily related to the issue under discussion).

The distance from the Sinpo submarine SSBA dockyard to Anderson AFB on Guam is ~3357.5 km, in agreement with the distance mentioned in the KCNA statement. Taking into account Earth rotation, the flight trajectories of the missiles when launched from Sinpo would indeed cross over the three Japanese prefectures mentioned, as can be well seen in the diagram in the top of this post. Together with the listed flight time, it would point to a flight apogee at ~865 km altitude and a launch elevation of ~31.4 degrees, i.e. a "normal" flight trajectory for an IRBM (as opposed to the "lofted", reduced range trajectories of previous tests).

click to enlarge

The map in the top of this post displays the flight trajectories based on this scenario, with the four missiles straddling Guam at ~40 km distance of its shores, uprange, downrange and lateral to both sides of the main flight direction needed to reach Guam.

While the language of the KCNA release is threathening, it is important to realize it is not threathening an actual "attack" on Guam. They talk about a strike that will "envelope" the island with the missiles, each of them impacting at a distance of 30-40 km of the Guam shore.

With the listed 30-40 km offshore impact distances, the missiles would land outside of Guam's territorial waters: but in its Exclusive Economical Zone (EEZ). While sensitive, this is something else than actually hitting Guam or the territorial waters directly surrounding it. The latter would be a real attack on US territory.

Targetting the EEZ has earlier precedents, as recent North Korean missile tests have landed in the Japanese EEZ. What makes it different this time is that it is the EEZ of the US itself, not of an ally, and involves a fly-over of Japan.

Rather than an attack, the scenario painted by the KCNA announcement would be best described as a missile test and demonstration. A test, because it would be the first flight of the Hwasong-12 on a "normal" battle trajectory rather than a "lofted" trajectory. A test, as it would for the first time have the Reentry Vehicle (RV) face the atmospheric reentry conditions it would face if used in an actual conflict. A demonstration, as it would demonstrate that the Hwasong-12 can indeed reach targets at the distance of Guam. A demonstration, as straddling Guam with missile impacts obviously sends a very clear message to the US and its allies.

It would also potentially test the Hwasong-12's performance against US missile defense measures. And it would be a (risky) political test to see how the US and its allies would react to such a demonstration of military power.

How likely is it that it will happen? On the face of it, not that likely. It most likely is hollow rethoric. Firing missiles towards a US military base and US territory is very risky as it could provoke a disastrous counter-attack. A full scale US counter strike would mean the end of the North Korean regime.

However, the oddly detailed August 10 KCNA announcement (which as some analysts on Twitter mentioned almost reads like a NOTAM) could also be seen as a way to mitigate this risk. It clearly signals the intention to not hit Guam itself, just fire near it in a demonstration of power. It is in essence a (tough worded) notice of an upcoming missile demonstration, not an actual war threath.

We should also realize that a US counter-attack would be disastrous for both North Korea and the US and its allies. If the US counter-attacks, North Korea will respond by shelling Seoul into oblivion and, if it can, firing missiles towards targets in South Korea, and possibly towards Japan and US bases in the Pacific. The carnage will be incredible. Hence, a military strike on North Korea as a gut-reaction to North Korean missiles landing near Guam is not as likely as it might at first glance seem. A sane US response would be to restrain from such a counter-attack unless there are strong reasons to do so, like missiles actually hitting targets on Guam. North Korea might have made a similar assessment. But it is a risky one (also taking potential missile malfunctions into account).

North Korea however has taken bold calculated risks before. They recently fired missiles into the EEZ of Japan, a key US ally. They took a risk in sinking the Cheonan in 2010, and shelling Yeonpyeong island that same year.

It is important to note the recent impact of North Korean missiles into the EEZ of Japan, given that the August 10 KCNA announcement points to targetting the EEZ of Guam. This firing into the EEZ of Japan did not lead to military retaliation by the US and allies (and in a sense perhaps might be seen as "testing the waters"). This might embolden North Korea to fire into the EEZ of Guam, expecting (rightfully or not) a similar non-response.

What could the US realistically do in response? As mentioned, a counter-attack in response to the missile firings would lead to dramatic results for the US and its allies. Seoul and Tokyo and who knows Honolulu burning seems a steep price to pay for "acting tough" when the missiles provoking the response harmlessly landed in the Pacific Ocean outside of Guam territorial waters. I fail to see how the US can justify such a result to its citizens and allies when the target of the missiles is in the Guam EEZ and not Guam itself.

Alternatively, the US or allies could perhaps attempt to intercept the missiles. That sounds like a good middle ground but isn't, as it has its own risks. Intercepting missiles on a trajectory that would not reach Guam territorial waters would provide political fuel to North Korea, who can claim their missile test was attacked. Moreover, there is a serious risk that an intercept attempt partly or wholy fails. That would seriously damage the credibility of the US and its capacity to defend itself and its allies, and with that seriously undermine the faith of US allies in the region (apart from the general loss of face). An attempted missile intercept would therefore be unwise in my opinion, as it would be a win-win situation for North Korea no matter the outcome.

So to me, it seems that North Korea is playing a high level (if dangerous) game of chess here, and has managed to checkmate the US. There seems very little the US realistically can do about it, apart from denouncing it. And the tougher the talk from Washington, the more face they will lose if it happens. "Hold my beer", you can hear Kim say in response, knowing he got them cornered.

In case North Korea does go forward with the announced missile demonstration, I expect Trump to do what he has done before: back-peddle on his earlier tough talk and grand-standing. And obscure this by making some unrelated outrageous policy decision or statement in order to deflect attention away from this political defeat, just as he has done with earlier political defeats.

Maybe the North Korean announcement is just a hollow threath. Maybe it is not. More likely than not it will not happen. But I would not exclude it entirely from happening, if North Korea made a similar assessment as outlined above. We will see.



UPDATE  15 aug 13:25:

The North Korean KCNA published a  bulletin on August 15, also carries by Rodong Sinmun. Apart from some interesting statements that might suggest North Korea has put a test fire towards Guam on hold for a while, the Rodong Sinmun newspaper contains some interesting photo's (pdf here via KNCA Watch):

images: KCNA/Rodong Sinmun

Two items on these photographs are of interest: the image on the wall at right, which depicts Anderson AFB on Guam. The other one is the map in front of Kim Jong Un (I put it upside-down here to have north up in the map):


image: KCNA/Rodong Sinmun
This map clearly depicts a missile trajectory towards Guam, that is very close to the trajectory I presented earlier in this blog post. The point of origin of the trajectory indeed seems to be Sinpo on the southeast coast.

UPDATE 2 & 3, 16 Aug 2017 00:30 & 2:45 UT:

Some claims appeared on Twitter that according to South Korean analysis, the map points to launch from Musudan-ri rather than Sinpo:




I do not agree. I used my GIS skills to georeference and reproject the map in front of Kim Jong Un. Below is the preliminary final result:

click to enlarge

What can be seen is that the drawn trajectory points clearly and unequivocally to Sinpo, not Musudan-ri.

What also can be seen is that the line drawn on Kim Jong Un's map is a simple straight drawn line rather than a real missile trajectory. The blue line I have drawn in the map is a true trajectory, including earth curvature and earth rotation and taking the map projection into account. The dashed red line I have drawn is merely a straight line (ignoring map projection).

The country outlines have been added in by me to show how the georeferenced image matches a true map.

Saturday, 29 July 2017

North Korea's July 28 ICBM test


On 28 July 2017 around 14:45 UT, North Korea tested another ICBM. Early reports from US Military sources indicate a night-time launch from a new location (Mupyong-ni), an approximately 45 minute flight time, and launch into a highly lofted trajectory with an apogee as high as 3700 km and a range of about 1000 km, with the launch direction towards Hokaido.

These ballpark figures allow us to estimate a ballpark maximum range for this ICBM. Because this was (again) a lofted test with an almost vertical launch, the true range of the missile is much more than the ~1000 km of the test when it would have been launched on a more normal trajectory.

The results I get are shown in the figure above: using the same delta V impulse as the lofted test but putting the apogee at 1200 km (a typical ICBM apogee) and roughly same launch direction, I get a range of ~8700 km.

That is probably a conservative figure. The true range depends on various factors (including the weight of the warhead, but also whether this test was at maximum missile performance. Reasons why it was perhaps not, is that North Korea might have shown some restraint and  taken precautions in order not to land their missile in or too much near Japan. This is also why they launch in a lofted trajectory).

In the figure above, I have drawn what this cautious reconstruction of the real range entails. It surpasses the distance to Hawaii. It brings San Francisco on the US West Coast in range. Today's test therefore implies that North Korea can strike the US mainland.

Towards the other direction, it brings Moscow in range, and if the true maximum performance of the missile is slightly larger, also Western Europe (*).

By the way, just as with the previous July 4th test, the Russians have come with maverick data for this test again, quoting a much smaller range and lower apogee (732 km and 681 km) based on their own Early Warning Radar observations. There are suspicions that their data only pertain to observations of the ICBM's first stage, explaining the discrepancy.

The analysis in this post is based on the first released ballpark figures for this test. If better data are released, the outcome might slightly change.


UPDATE: North Korea has now published the following figures for their test: apogee  3724.9 km, range 998 km, flight time 47m12s. They say it was a Hwasong-14 tested to simulate maximum range. Photographs published indeed show a missile similar to the one launched on July 4.

photo: Rodong Sinmun

photo: Rodong Sinmun



* the maximum range is (unlike depicted above) not a neat 8700 km circle. The maximum range depends on which direction is launched into, due to Earth rotation effects. Due to this, when launched towards the east the missile will have a somewhat larger range than when launched towards the west. Launched towards the east it gets an extra "push" from the rotating Earth.

Saturday, 1 July 2017

OT: Broek in Waterland, the sixth Dutch meteorite (observed fall, 11 January 2017)



Last Monday was a special and extremely busy day. At Naturalis, the Dutch National Museum of Natural History, we presented a new meteorite: Broek in Waterland (provisional name). It is an L6 chondrite and only the 6th authenticated meteorite of the Netherlands in 177 years time, after Uden (LL7, fall, 1840), Utrecht (L6, fall, 1843), Diepenveen (CM-an, fall, 1873), Ellemeet (DIO, fall, 1925) and Glanerbrug (L-LL4-5, fall, 1990).

(left to right) The author and Leo Kriegsman (Naturalis) and Niek de Kort (Royal Dutch Association for Astronomy) with the new Broek in Waterland meteorite at the presentation in Naturalis Biodiversity Center, 26 June 2017

On 11 January 2017 at 16:08:40 UT (17:08:40 local time), just after sunset, a bright fireball appeared over the Netherlands. The sun was only 3 degrees below the horizon and the sky still bright blue and star-less at that moment, so unfortunately the Dutch-Belgian photographic all-sky network and the CAMS BeNeLux videonetwork where not yet operational. Dozens of people from the Netherlands and Belgium however visually spotted the fireball and reported it.

A driver on a highway near Weerde in Belgium, 165 km from the fall locality, captured the fireball with a dashcam and uploaded the video to a Belgian UFO investigation website. No other video records besides this one have surfaced, unfortunately. From a comparison of the road marking patterns on the video with Google Earth imagery, I determined that the fireball (going almost straight down in the video) appeared near geodetic azimuth 11-15 degrees. Broek in Waterland, where the meteorite was subsequently found, is in azimuth 11.5 degrees as seen from this locality, i.e. a very good match.




The next day, the owners of a garden shed near Broek in Waterland, a rural village just a few km north of Amsterdam, noted roofing tile shards on the ground next to the shed. Upon investigation, they discovered something had smashed through the roof and lodged on the supporting latticework. It was a 530 grams black stone, about 9 cm in diameter, the size of a small fist.




The Broek in Waterland L6 chondrite (click images to enlarge. Photographs by the author, 3 Feb 2017)

Puzzled by the curious incident, one of the finders started to search the internet for explanations. Two and a half weeks after the fall, she phoned Niek de Kort, who runs the Meteorite Documentation Center of the Royal Dutch Association for Astronomy and Meteorology. Niek was abroad at that moment, but the description and subsequent e-mail with pictures sounded very promising. He allerted Leo Kriegsman and the author (Naturalis Biodiversity Center, the Dutch National Museum of Natural History). We made an appointment with the finders and visited them at the fall locality on February 3, where we formally established that the stone was indeed a meteorite. From the look of it, I provisionally determined it as likely an L6 Ordinary Chondrite (a common type of stony meteorite). Subsequent laboratory testing has confirmed that initial assessment.

We arranged a temporary loan of the stone with the owners and got permission to cut off 20 grams for research. Subsequent laboratory research at Naturalis and Utrecht University with thin sections, XRF and microprobe confirmed that the petrology, mineralogy and chemistry was consistent with an L6 Ordinary Chondrite. Measurement of shortlived isotopes at the VU University Amsterdam found isotopes that confirm this is a recent fall.

The meteorite's pre-sampling weigth was 530 grams. It is fist size, and almost completely fusion crust covered, bar a few chips and scratches from the impact on the roof. One side of the stone is rounded, the other side shows flat facets, the larger ones of which are covered in "thumb prints" (regmaglypths). This evidences breakup of the stone during the ablative phase of entry into the atmosphere.


search activities in the fall area, February 2017 (photograph by author)

In the weeks after the stone came to light, I teamed up with Felix Bettonvil of Leiden Observatory to organise a search for more fragments in the surrounding area. Some fifteen volunteers, many of them veterans from earlier meteorite search attempts, from the Dutch Meteor Society, the KNVWS meteor section, Naturalis and Leiden Observatory, spend several weekends  meticulously searching a large area around the fall site, but no other fragments were found. The area in question has a lot of open water and is very swampy: part of the area is a nature reserve and a peat bog where, if you jump up and down, the ground surface starts to form waves, and it makes squishy sounds when you walk there. We used long metal rods to probe suspicious holes in the ground. Searches were halted when late March the bird breeding season started, and the area became temporarily prohibited for that reason.

Broek in Waterland is only the 6th authenticated meteorite of the Netherlands. The previous meteorite fall, Glanerbrug on 7 April 1990, was 27 years ago. It impacted on the roof of a house. We suspect, based on the total land surface of our small country, that on average about each three years a 0.5 kg meteorite lands somewhere in the country. Yet, we have on average recovered one only each 30 years. Evidently, a lot of them, 9 out of 10, fall straight into oblivion. The large amount of open water and generally swampy nature of much of the Netherlands, with very soft peaty and clayey substrates, might play a role here.


The location of Broek in Waterland, and the other Dutch meteorite fall localities (map by author)

All six Dutch meteorites are witnessed falls. The pre WW-II falls (Uden, Utrecht, Diepenveen and Ellemeet) all were recovered because the meteorite landed close to someone working the fields. With the mechanisation of agriculture post WW-II this no longer happened. The two post WW-II meteorites, Glanerbrug and the new Broek in Waterland, were recovered because they hit a building and caused damage.

We are actively trying to find meteorites and have been organizing dedicated searches a number of times, based on fireballs captured multistation by our photographic all-sky fireball camera network. Examples are a fireball from 2013 near Hoenderloo and another one from 2015 in Gaasterland. None of these searches was succesful.

The press attention on June 26, when the existence of the Broek in Waterland meteorite was made public by Naturalis, was enormous. We have been busy from 7 am in the morning to 1:30 am the next night, with Leo, Niek and I giving dozens of newspaper, radio and TV interviews. In the late evening of June 26 I was a table guest in a well-watched talkshow on Dutch television, RTL Late Night, live broadcast from Hotel Schiller in Amsterdam, showing the meteorite and talking about it with host Humberto Tan, with science journalist Govert Schilling as my side kick (or me as his, depending on your point of view).

the author (middle) as well as science journalist Govert Schilling (left) with the meteorite in RTL Late Night, 26 June 2017
RTL Late Night show host Humberto Tan with the meteorite

Tuesday, 6 June 2017

[UPDATED] Close Encounters of the Classified Kind: a post-event analysis of the close approach of USA 276 to the ISS on June 3

3 July 2017: A paper which is a further evolved version of this blog post has appeared in The Space Review. I advise you to read that paper



(UPDATED 7 Jun 2017 15:50 UT with two new figures showing circular motion of USA 276 around the ISS)

Something odd happened a few days ago, high above our heads. In an earlier blogpost, I discussed in detail how the odd spy satellite USA 276 (2017-022A) was set to make a peculiarly close approach to the International Space Station ISS on 3 June 2017. The spy satellite was recently launched for the NRO as NROL-76 by SpaceX, on 1 May 2017.

With the close approach moment now in history and post-approach observations of USA 276 available (as well as an orbit for ISS based on tracking data, rather than an orbital prognosis), I present my final analysis of the situation in the current post.

With the new data included, we can establish the moment of closest approach as 3 June 2017, 14:01:52 UT. It happened over the southern Atlantic north of the Falklands, near 43o.75 S, 45o.45 W, with a miss distance of only 6.4 ± 2 km (the  ± 2 km stems from the fact that TLE predicted positions have a typical positional accuracy of no more than 1 km at epoch).

The latter is significantly closer than the approach distances calculated before the approach (which were in the order of 17-20 km, see my earlier post). Ted Molczan also analyzed the situation and he finds an even closer nominal distance of 4.5 km (but within uncertainty intervals our results overlap).

For the ISS, I used elset  17154.48611204. For USA 276, I used the elset below which I calculated based on amateur observations including my own:


USA 276
1 42689U 17022A   17155.88026473 0.00004763  00000-0  65979-4 0    01
2 42689  50.0047 103.5284 0014136 110.9138 249.3345 15.56256291    00

rms     0.020                             arc May 31.92 - Jun 4.90 UT


For detailed purposes like this, the orbit determination is a bit sensitive to what observer data are included. I restricted myself to observers with known high accuracy in the orbital solution above.

click image to enlarge

click image to enlarge

Below is an updated animation of the situation:




A table of all close approach moments with distances smaller than 500 km:

DATE       UT         km 
3 JUN 2017 02:28:52   478.5 
3 JUN 2017 03:13:37   464.4 
3 JUN 2017 04:01:17   413.2 
3 JUN 2017 04:46:14   398.9 
3 JUN 2017 05:33:41   347.8 
3 JUN 2017 06:18:50   333.3 
3 JUN 2017 07:06:04   282.4 
3 JUN 2017 07:51:26   267.7 
3 JUN 2017 08:38:28   217.1 
3 JUN 2017 09:24:03   202.2 
3 JUN 2017 10:10:52   151.9 
3 JUN 2017 10:56:39   136.6 
3 JUN 2017 11:43:15    87.1 
3 JUN 2017 12:29:16    71.0
3 JUN 2017 13:15:38    26.3 
3 JUN 2017 14:01:52     6.4  **
3 JUN 2017 14:48:01    48.8 
3 JUN 2017 15:34:28    60.5 
3 JUN 2017 16:20:24   112.5 
3 JUN 2017 17:07:05   126.1 
3 JUN 2017 17:52:46   177.5 
3 JUN 2017 18:39:41   191.7 
3 JUN 2017 19:25:09   242.9 
3 JUN 2017 20:12:18   257.4 
3 JUN 2017 20:57:31   308.3 
3 JUN 2017 21:44:54   323.1 
3 JUN 2017 22:29:53   373.7 
3 JUN 2017 23:17:30   388.8 
4 JUN 2017 00:02:15   439.2 
4 JUN 2017 00:50:07   454.5

Note: as positions from TLE's have an intrinsic uncertainty (about 1 km at epoch time), the values in the table above have an uncertainty of about 2 kilometer.

The distance variation around close approach in diagram form:
click diagram to enlarge

click diagram to enlarge

The variation in orbital altitude of both objects around the time of close approach (actual geoid heights):

click diagram to enlarge
As can be seen, USA 276 was a few km (nominally 3.65 km) above the ISS at closest approach. It was nominally also a little bit over 5 km behind the ISS.

In the following diagram, nominal distances in km in X, Y and Z of USA 276 are measured with respect to the ISS. The X is in the direction of movement of the ISS, Y is perpendicular (lateral) to it, Z is the zenith-nadir direction:

click diagram to enlarge

[UPDATE 7 Jun 2017, 15:45 UT, revised 21:14 UT] The variation in position of USA 276 with respect to the ISS was such that it effectively circled the ISS at close approaches, both laterally (cross-track) as wel as along-track, as can be seen in these diagrams below. Please note that, to get a more clear diagram, the axes of the first diagram (crosstrack circling) are not to scale. The second diagram is the same figure, but with axes to scale. The third diagram (along track circling) is also to scale:

click diagram to enlarge
click diagram to enlarge
click diagram to enlarge

A collision avoidance manoeuvre is usually evaluated if an object comes within a box of 4 x 4 x 10 km of the ISS.

If upon further evaluation the chance of collision is larger than 1:10000, an avoidance manoeuvre is done, if circumstances allow this.

USA 276 remained just outside the 4 x 4 x 10 km box at closest approach, as can be seen in the illustration below (red box, the situation shown is for the moment of closest approach). The box represents a collision risk in the order of 1 in 100 000.

USA 276 relative to the ISS proximity safety box . Click image to enlarge  (image made with STK)

I remain agnostic on the question whether this close approach was intentional or not (see discussion in my previous post regarding some possible goals would the approach  have been intentional).

Ted Molczan published a discussion of pro and contra arguments on the question whether the approach was on purpose or not on the Seesat-L list on June 3. While Ted argues that the April 16 and April 30 postponements of the launch indicate a non-planar preference of the orbit (which argues against intention), this also means that this close approach could have been avoided by picking another launch moment.

While USA 276 remained just outside the safety concern box, it is weird to have your just launched classified payload pass so close (6.4 ± 2 km) to a high profile, crewed object like the ISS.

I can and do not believe for a moment that the NRO was not aware that the launch on May 1 would lead to the close ISS approach a month later. It would be extremely sloppy of them, from a Space Situational Awareness viewpoint, if they were not aware, especially given how close the orbital parameters are to that of the ISS.

So I am struggling to understand why the NRO allowed this close approach to happen, if it was not intentional. This event was bound to attract attention and that harms the classified character of the mission. USA 276 is relatively brigh and the approach was bound to be noted by independent observers. Indeed, some space enthusiasts in Europe unaware of the issue who were out to spot DRAGON CRS-11 and Cygnus OA-7 close to the ISS on June 4, did accidentally spot USA 276 passing some 3 minutes in front of it.

It is also an extremely sloppy thing to do because this close an approach to a high profile object like ISS is politically risky. As the ISS is an international cooperation which includes two parties (the United States and the Russian Federation) that are currently geopolitically on an uneasy footing, sending your military payload so close to the ISS as one party is eyebrow raising.

This, and the timing (the close coincidence with the Dragon CRS-11 arrival at the ISS [edit: this refers to the originally planned date of arrival at June 4, later postponed by one day]) was bound to generate questions and suspicions (as it did). What the NRO did with USA 276 in the last few days was therefore really weird.

But then, the current administration of the USA is doing very weird things, and perhaps someone in the new administration signed off on this without fully understanding the depths of it. The Trump administration after all is not quite the posterchild for competence.

(the video below shows a USA 276 pass I filmed in evening twilight of June 4, at low elevation)