Sunday, 20 September 2020

Observing the mysterious "Object A" (2020-063G), left in orbit by China's 'Spaceplane'


Earlier this month I wrote a post about China's brand new, recently launched and landed 'Reusable Test Spacecraft' (2020-063A), probably a 'Spaceplane' similar to the US  X-37B. It was launched on September 4 from Jiuquan, and landed on September 6 at Lop Nor, after two days on orbit (see a previous post).

As I noted near the end of that post, it left something in orbit: an object of unknown character, which the US Military tracking network now calls 'Object A' (a bit confusing I think, as the COSPAR code is 2020-063G - so I'd called it 'Object G'). It is in a 347 x 331 km orbit.

click diagram to enlarge

This does not appear to be just a piece of debris - e.g. some discarded cover. Radio observers discovered that it sends a signal in the L-band near 2280 MHz, something debris doesn't do. So, this appears to be an interesting object that had or has some function, including a radio data signal downlink. It does not appear to have manoeuvered so far, and if it is tumbling (see below) it isn't likely to do so..

I initially thought that it might be a cubesat, but it appears to be rather large for that. At maximum brightness it reaches magnitude +4, i.e. it is visible to the naked eye. Speculation is that it is either an inspector satellite used to inspect the outside of the Chinese spaceplane before landing: or maybe some jettisoned support module. The ejection from the 'Reusable Test Spacecraft' appears to have taken place some two revolutions before landing, or perhaps even earlier (see brief analysis at the bottom of a previous post).

I filmed the object this morning with the WATEC 902H equipped with a 1.8/50 mm lens - see the movie above. The mysterious object showed slow but marked brightness variations, between magnitude +4 and invisible (= fainter than +7). This confirms reports by radio observers of periodic fading in the signal.

Below is the brightness curve that I extracted from my video, using LiMovie. I was handtracking the object, and halfway lost it for over half a minute when it became too faint for the WATEC 902H (equipped with a 1.8/50 mm lens): hence the half-minute gap in the curve. The other, smaller gaps in the curve are moments that I repositioned the camera. One of these days, I really have to start using a motorized mount tracking on the satellite for this kind of endeavours.

The curve shows two brightness peaks, and two major fading episodes. Peak-to-peak period is about 80 seconds, so if this is due to a tumble, it is a slow tumble.

click diagram to enlarge

When I first picked it up (it had just come out of earth shadow), it initially was very bright and steady (see the movie in top of this post). But then it started to get fainter, untill I momentarily lost it. When I picked it up again, it was becoming brighter again, and after a slow peak, it faded again to invisibility. The fades are faster than the brightening phase and brightest phase.

Thursday, 17 September 2020

The structure of Space (2): formation of a geosynchronous ring


A year ago, I published a post on 'The structure of Space'. In that contribution, I discussed structure in orbital element space, identifying spacecraft 'families'. But how about 'structure' in a more traditional spatial sense?

A few days ago, I had some light Twitter-banter with the fantastic Alice Gorman ( aka 'Dr Spacejunk'). She asked

"why is it that space junk has not turned into rings around Earth, just like Saturn or Neptune? Kessler and Cour-Palais (1978) argued it was because the smaller particles were removed by atmospheric drag before enough mass could accumulate"

I pointed out that our Earth by all means does have an artificial ring of space debris and functional payloads: the geosynchronous ring. Which, as we will see, is more of a geosynchronous torus, actually. It is not so dense (yet) with objects as the rings of Saturn or Neptune (but give it time!), but it will be long lasting, outliving us humans.

This sparked a few creative days (I had to get my mind off a few things). I wrote a small .NET application that calculates ECEF coordinates of satellites and fed it with all objects from the CSpOC and our classified catalogues: 20058 tracked objects ranging from operational payloads to small debris particles. Next, I used QGIS to make plots of these ECEF coordinates (I know: I often tend to use software for things other than what they originally were developed for).

The results are in the images below: each image pair shows a polar view at left looking down at the north pole, and a side view at right, looking in the equatorial plane. The plots are for 15 September 2020 at 0h UT.

Here is a zoomed in view, showing the objects in lower orbits (left a polar view, right an equatorial view: thickmarks are un units of 2000 km):

Click image to enlarge

As an aside: notice the small circular area with lower object density at the pole, rimmed by a higher density ring (it is also visible in the wider plot below). This is due to the fact that objects in polar orbits tend to have orbital inclinations  a few degrees higher than 90 degrees: notably so to achieve a sun-synchronous orbit (typical orbital inclinations for such orbits are 97-98 degrees).

In the wider, zoomed out plots below that show the higher objects, you can clearly see the geosynchronous ring at ~35785 km in the polar view at left (thickmarks are at units of 10 000 km). It is made up of geostationary and geosynchronous satellites and debris.These are the satellites that bring you satellite television, satellite telephony, and that bring SIGINT and early warning data to the militaries of various governments. The objects inside the outer ring are objects in MEO (e.g. GPS satellites) and GTO (old rocket stages form launches to GEO and other debris):

Click image to enlarge

If you look at the equatorial view at right, you'll note that the geosynchronous 'ring' is actually more a geosynchronous torus. You see a thin line of actual geostationary objects (mostly operational or untill recently operational payloads) in the Earth's equatorial plane with orbital inclination ~0: and a wider band of geosynchronous objects, that have orbital inclinations between roughly 0 and 15 degrees (both operational payloads, defunct payloads including some in a graveyard orbit, and debris).

The latter torus is situated slightly slanted with respect to the Earth's equatorial plane. The orientation of this slant shows a daily cycle, causing a funny 'wave' like behaviour of these satellites over a full day, when we look at their geographic positions in the equatorial plane, as can be seen in this mesmerizing animation that I created:

click animated map to enlarge

In this animation, the colours represent the object density plotted as a kernel density heatmap: red areas are most dense with objects. The small white dots are the actual geosynchronous satellites (plotted for 15 September 2020). There is a thin line of objects at latitude ~0 that are truely geostationary due to stationkeeping: these hardly move. But the geosynchronous objects with inclinations > 0 show a wave-like pattern of movement over the day!

This movement is a tidal effect, created by solilunar perturbations: gravitational perturbations by the sun and (notably) the moon. These tug on these objects a little, so unless you do frequent stationkeeping manoeuvers that keep the orbital inclination near zero, these objects will see their orbital inclinations start to oscillate, between 0 and 15 degrees over a period of roughly 54 years (53-55 years: it depends on the exact altitude of the satellite). This causes the torus. The daily 'wave' (wobble) of this torus is caused by these tidal effects too, similar to ocean tides.

I have visualized the discussed ~54-year oscillation by plotting the evolution of the orbital inclination against time of Intelsat 1 (1965-028A), the first commercial geostationary satellite that was launched in 1965. It has just completed a full cycle of this moon-and-sun induced oscillation since it's launch:

click diagram to enlarge

In the absense of active stationkeeping (operational payloads make stationkeeping-manoeuvers roughly each two weeks), there is an oscillation in longitude too, induced by the J2 resonance: due to the uneven mass distribution of the Earth (it isn't a perfect sphere but rather a slightly deformed, bulgy egg), geosynchronous objects without stationkeeping start to oscillate in longitude around one of two "stable" points. These points are at ~75 E and ~105 W longitude: the white crosses in the plot below.

click map to enlarge

This oscillation in longitude about one of the stable points is well visible in 55 years of Intelsat 1 orbital data. Below I have plotted the position of the satellite in longitude from 1965 to 2020. You clearly see it oscillate around one of the equilibrium points (the 105 W point, marked by the dashed line in the diagram), with a periodicity of about 3.1 years:

Click diagram to enlarge

Over time this effect will also tend to concentrate space debris at geosynchronous altitudes around these two points. This effect can be seen in the kernel density heatmap (the coloured band) above the diagram, and in the histogram below (two peaks in the distribution, near the first equilibrium point at 75 E and the second equilibrium point near 255 E = 105 W) although it is to some extend masked by a preference of operational payloads to be at the longitudes of either Asia or the USA, where the biggest commercial markets for satellite tv and satellite telephony are.

click diagram to enlarge

Objects at geosynchronous altitude will not decay in millions to perhaps billions of years to come: so the geostationary ring that formed since 1965 will be here to stay, well after we humans are gone. It will be one of the clearest, longest lasting archaeological signatures of the Anthropocene.

Of course the character of the ring will change. Breakups will fragment the larger objects, decreasing the particle size distribution and increasing the number of objects in the ring even when human launches have stopped. Solar Radiation Pressure will more strongly acht on smaller particles, so orbital eccentricities (and presumably also inclinations) will change, causing the ring to get more diffuse in time. I do not know of really long-term simulations (the longest I have been able to find was over a mere 200 years period), so cannot put exact figures on this.

The geosynchronous ring is a remarkable form of planetary change: untill quite recently our planet did not have a ring, but now it has, and it is completely artificial. It formed in a short time. In the animation below, I have broken down the current distribution of objects in the ring (for 15 September 2020) into launch timeframes of 5 years, starting 1960 (i.e. just before the first geostationary launches started) and ending at present:

This shows the gradual, but in terms of geological time nevertheless extremely rapid formation of our planet's artificial ring over the past 55 years. This ring will be a long-lasting, visible human footprint in space, probably outlasting all others (including footprints on the moon, that will be wiped out over time by meteorite impacts).

If you have a telescope or a good camera, you can see this ring of objects every night. Here is a photograph of a small part of it:

Click image to enlarge

Friday, 11 September 2020

Important update of my SkyTrack software [UPDATED]


In the context of the probable landing site of the recent Chinese Experimental Spacecraft (see previous post), I discovered a serious bug in my SkyTrack software.

As it turns out, when your chosen observing site has an altitude well over MSL, the sky positions in RA/DEC and AZIMUTH/ELEV are significantly off in version 2.5. I had not noticed this before, as my own observing location is at MSL.

The reason for this error is stupid: the SGP4 DLL needs an altitude in km, while in my code I failed to convert the site altitude from meters to kilometers....hence, a site at 995 meter was treated as if was a site at 995 km...oopsie!

Anyway: I have corrected the error and the new version 2.6 is now for download at my software website.


UPDATE 12 Sep 2020:

A second important bug fix was made, leading to version 2.7 now downloadable.

It corrects an error where, when adding a new site, southern latitudes and western longitudes were incorrectly written to the database...


Starting version 2.6, I also included a few lines of code that should solve another problem and forces the software to recognize the dot as the decimal separator during runtime of the program, no matter what your regional windows setting is. This likewise avoids output errors.

For those unfamiliar with the software, there is an earlier blogpost detailing it.

In short, the software takes as input a set of orbital elements in TLE-format, and allows you to calculate, for a given custom time interval in custom time steps:

- The latitude, longitude and altitude of the satellite;

- An indication whether it is sun-illuminated or not;

- the Right Ascension (RA) and Declination in the sky, for your observing site;

- the Azimuth and Elevation in the sky, for your observing site;

- the Range (in km) to your observing site;

...and optionally also:

- a KML file of the trajectory that you can load into Google Earth;

- the Doppler-corrected radio frequency (for a given central frequency);

- EFG (ECEF) x, y, z coordinates of the satellite;

- format the data as .csv so it can easily be imported into mapping applications like QGIS.

- choice between various output formats and Datums for the Lat/Lon and RA/DEC data

The software also has options to restrict the output to a certain minimum elevation as sen from your observing site, and/or output only when the satellite is sun-illuminated (and hence visible).

Saturday, 5 September 2020

China launches a 'Reusable Experimental Spacecraft' - a Space Plane? [UPDATED MULTIPLE TIMES]

Early September 2020, the space tracking community was in nervous anticipation of a rather mysterious Chinese launch. Amidst tight security measures, a Changzeng-2F (CZ-2F) rocket was readied at SLS-1 of Jiuquan's Launch Area 4. Chinese tracking ships were taking up positions near South America and in the Arabian Sea. Two NOTAM's appeared suggesting a launch between 5:20 and 6:00 UT on September 4. Something was afoot! Speculation was, that this was the long anticipated inaugural launch of a robottic Space Plane, a version of the Shenlong, China's answer to the American Air Force's X-37B robottic Space Plane.

Then, on September 4th, the Chinese news agency Xinhua published a very brief news item announcing that a CZ-2F from Jiuquan had launched a 'Reusable Experimental Spacecraft' earlier that day. 

The bulletin was scarce in information but stated that "after a period of in-orbit operation, the spacecraft will return to the scheduled landing site in China. It will test reusable technologies during its flight, providing technological support for the peaceful use of space".

No further details were given on launch time, orbit or character of the spacecraft. The description of the spacecraft is a bit ambiguous. Instead of a space plane, a 'reusable spacecraft' could in theory also be some sort of capsule (e.g. like the SpaceX Dragon): but most analysts think this indeed refers to the long rumoured space plane, China's answer to the US X-37B.

Pre-launch, and based on the positions of the hazard zones from the two NOTAM's, I calculated a launch into an orbital inclination of ~45 degrees, incidentally similar to the orbital inclination of the X-37B OTV 6 mission currently on-orbit. What's more, the launch window given (the NOTAM windows were from 5:23 to 6:05 UT) indicated the possibility of a launch into the orbital plane of OTV 6! The orbital plane of OTV 6 passed over Jiuquan at 6:00 UT - near the end of the launch window.

I published the following expected track for a launch into a 45 degree inclined orbit (which we now know is wrong):

Initial pre-launch trajectory guess. Click map to enlarge

When later that day the first orbital elements by the US military tracking network appeared on the CSpOC portal, it turned out that the orbital inclination was not ~45 degrees, but 50.2 degrees, 5 degrees higher than I anticipated. The reason for the mismatch, is that the rocket apparently did a dog-leg manoeuvre during ascend. This is very clear when we plot the orbital ground track in relation to the launch site and hazard zones from the two NOTAM's: it passes obliquely between them rather than lining up.

Actual orbital track. Click map to enlarge

 A 'dog-leg' manoeuvre is usually done for safety reasons, to avoid overflying a particular area downrange (e.g. a city or a foreign nation), but can also be done to insert the spacecraft into an orbital inclination that otherwise cannot be reached from the launch site. The latter is however not the case here - [editted] the orbital inclination is higher than the launch site latitude (you cannot reach an orbital inclination that is lower than your launch site latitude without a dog-leg, but higher you can.). So the reason must be range safety.

It is clear that the launch occurred well outside the NOTAM time window (why, is not clear). My analysis, based on a proximity analysis using the orbits of the spacecraft, the upper stage of the CZ-2F rocket, and that of four engine covers ejected upon spacecraft separation, indicate spacecraft separation and insertion into orbit around 7:41 UT on September 4th, over the Chinese coast with the orbital plane lining up with Jiuquan (see image below which depicts the orbital position at orbit insertion). The launch itself then should have occured some 8-10 minutes earlier i.e. around 7:30 UT, give or take a few minutes.

Moment of orbital insertion. click to enlarge

The spacecraft was inserted into a 50.2 degree inclined, initially 332 x 348 km orbit. During the hours after launch, the spacecraft made small orbital manoeuvres (see diagram below). At the time of writing (5 September 20:45 UT) it is in a 331 x 347 km orbit.

click diagram to enlarge

The later than initially expected launch time and, through a dog-leg manoeuvre, insertion into a 50.2 degree inclined orbit moved the orbital plane away from that of the X-37B OTV 6, although the two orbital planes are still near. Igor Lissov has pointed out some resemblance to the orbital plane of another US classified payload, USA 276, which has a similar orbital inclination to the Chinese spacecraft (but 50 km higher orbital altitude). The RAAN difference is 8 degrees:

click to enlarge

Based on the current orbits of all three spacecraft, there will be no close approaches of the Chinese spacecraft to either of these classified US payloads over the coming two weeks.

OTV 6 is currently in a 383 x 391, 45.0 degree inclined orbit. The difference in RAAN with respect to the Chinese spacecraft is 13.4 degrees, with a 5.2 degree difference in inclination and about 40-50 km difference in orbital altitude.

USA 276, the mysterious spacecraft that made a close approach to the ISS in May 2017 (see my July 2017 article in The Space Review), is currently in a 397 x 395, 50.0 degree inclined orbit. The difference in RAAN with respect to the Chinese spacecraft is 7.9 degrees, with a 0.2 degree difference in inclination and about 50-60 km difference in orbital altitude.

The Chinese 'reusable' spacecraft was launched from SLS-1, one of two launch platforms at Launch Area 4 of the Jiuquan Space Launch Center. Below is a Copernicus Sentinel 2B image of the launch complex, taken on September 2nd, two days before the launch. The two launch platforms are indicated: the southernmost one is the platform used for this launch.

click image to enlarge

It will be interesting to see where the 'reusable spacecraft' will eventually land. One likely candidate is a military airfield, the Dingxin Test and Training Base, that is located some 75 km southwest of the launch site. I have indicated both the launch site (A) and the potential landing site (B) in the Copernicus Sentinel 2B image below. The second image gives a more detailed look on the airbase.

Click image to enlarge

Click image to enlarge

We have no clue how long the spacecraft will stay in orbit. It will be interesting to see when and where it lands.

The 'reusable spacecraft' has the CSpOC catalogue entry #46389 (COSPAR ID 2020-063A). The CZ-2F upper stage is object #46390 (2020-063B). The four ejected engine covers (with apogees in the 458 to 566 km range), have numbers 46391-46394 (2020-063A to 202-063F).

UPDATE 6 Sept 2020 8:45 UT:

Xinhua reports on Sept 6 that the spacecraft has landed after 2 days on-orbit. Depending on the landing site, landing should have been (based on orbital overpass) either around 1:55 UT at Lop Nor (an alternative landing site suggested), or 6:45 UT at Dingxin Airbase.

UPDATE 2, 9:30 UT:
As the Chinese version of the Xinhua bulletin dates to an hour after the first option (1:55 UT), it seems that the landing was near 1:55 UT near Lop Nur in the Taklamakan desert (HT to Jonathan McDowell).

UPDATE 3, 10:30 UT:
This is the potential landing site, a triangular arrangement of 5 km long landing strips in the Taklamakan Desert. The orbital track of the spacecraft passed some 42.5 km northwest of it around 1:54 UT, more or less parallel to what appears to be the main landing strip:

Click image to enlarge

Click image to enlarge

UPDATE  4, 14:00 UT:
This is an updated diagram of the orbital evolution over the test flight. It seems no large manoeuvers were tried during this flight.

Click diagram to enlarge

UPDATE 5, 16:00 UT:

Jonathan McDowell noted that a new object related to the launch has been catalogued, object 2020-063G, #46395. My analysis suggests it was ejected from the experimental spacecraft near 22:25 UT on the 5th, two revolutions before landing. It likely is a cubesat of some sort. It is in a  332 x 348 km, 50.2 degree inclined orbit. (Update 8 Sept: on Twitter, Bob Christy has suggested that it might be a small inspector satellite, used to inspect the outside of the experimental spacecraft prior to deorbit)

Thursday, 6 August 2020

15 years of the SatTrackCam (b)log!!!

I hardly can't believe it: but today, this blog turns
15 years!

It all started very humble. The very first post on this blog, titled "Dutch weather sucks!", went up on 6 August 2005. It was a very simple, brief message, noting how I was defeated by weather that night.

Most of the early posts on this blog back in those days were such very brief and simple notes (but then, blogs back in those days were much more simple affairs). It were very basal, verbatim reports on my nightly observing activities. A lot of it was bitching on the proverbially bad Dutch weather (seriously: for a satellite tracker I am situated in one of this Worlds worst locations considering weather. And light pollution).

My equipment back in those days was very simple too: nowadays it is much more sophisticated (but still, all is done with off-the-shelf equipment that in itself need not be very expensive).

This blog is what I would call a Niche Blog: one that is dedicated to some weirdly esoteric field of interest. There are literally only a handfull of amateurs Worldwide who are actively tracking satellites, maybe 15 active observers altogether (but a lot more who like to read and talk about it). Space Situational Awareness, to use the professional terminology, is a decidedly geeky field.

The X-37B military space plane OTV 6 (click image to enlarge)

Therefore, it has always surprised me how many readers my blog draws, especially when something special is going on. In the latter case, this blog can draw an audience of thousands of readers per day. On a more typical day, it would be one- or twohundred per day at most.

Started in August 2005, this blog would grow over the next 15 years to become a much more mature, well established and apparently well-respected blog with a dedicated following of fellow satellite trackers from the SeeSat-L mailing list as well as an assorted lot of sundry general Space enthusiasts, Space Situational Awareness professionals, journalists, Missile geeks, and other people who somehow find their way to this blog.

And Spooks too. IP logs show that this blog has been visited by amongst others the CIA, the NSA and the North Koreans. It made me joke to my friends about black helicopters, unmarked SUV's, and I tongue-in-cheek asked them to send clean underwear to Gitmo in case I would suddenly vanish....  Another noteworthy, unexpected visit some years ago, was someone from the Executive Office of the US President (this was at the time that a malfunctioned Japanese spy satellite was about to come down).

Fifteen years ago, I'd never dreamt of such a wide audience. What originally was simply an on-line observing log (as reflected in the name), has by now become a well established military Space related OSINT blog.

Photography and data visualizations have been, and will continue to be, a very important part of what I write for this blog. While functional (astrometry), I always strife to make my imagery visually attractive as well.

My imagery inspired the artist and investigative journalist Trevor Paglen, so he told me, to create the chapter "The Other Night Sky" in his photobook Invisible. Covert Operations and Classified Landscapes.

With Trevor Paglen in Amsterdam in 2018

So how did it all start? During the Nineteen-nineties, previous to my interest in satellites (which came from an interest in satellite reentries), I was an active meteor observer within the Dutch Meteor Society. Back in 2005 I realised that the software we used to astrometrically measure meteor images, would be suitable for measuring positions on satellites in images too. Around that time I also discovered this weird but fascinating world of observers tracking classified satellites! So I started to experiment with that, and after a period of trial-and-error and discovering what was important (accurate timings and camera calibration!), I started to get usefull results. Soon, I became a regular contributor of positional measurements on classified satellites to the Seesat-L list.

Starting simply with a compact camera (a Canon IXUS gifted by a friend), the equipment has grown over the years. A significant quality change came when I landed a post-doc, got some money and turned to using a DSLR (initially a Canon EOS 400D; currently a Canon EOS 80D) and an over time growing  suit of suitable lenses (Canon EF 2.0/35 mm; Canon EF 2.5/50 mm, Samyang 1.4/85 mm; Samyang 2.0/135 mm; and in the past also a Zeiss 2.8/180 mm).

For Low Earth Orbit, I now preferably use a sensitive video camera (a WATEC 902H) with either a  Canon 1.8/50mm or Samyang 1.4/85 mm lens, and a GPS time inserter, as timing remains the bottleneck of using a DSLR. The DSLR is now mainly used by me for astrometry on high altitude objects (HEO and GEO), and for obtaining pretty pictures of Low Earth Orbit objects.

Over the past few years, radio was also added as an observing tool (although mostly focussing on Human Spaceflight communications and  capturing weather satellite imagery).

Click image to enlarge

As this blog matured, and I gained more insight into spaceflight dynamics (graciously helped along by people like Ted Molczan), the posts became more elaborate. The scope widened. I started to publish analysis, and these started to gather attention. A few years ago, my interest in the North Korean Space program expanded into an analytical interest into the North Korean missile program (which introduced me to the funny lot of people that populate the Missile Twitter community), and ICBM tests in general.

At one point, some of my analysis outgrew this blog, resulting in more formal articles written for The Space Review and The Diplomat (see links in the sidebar). Apart from my blog posts and articles, I also frequently present imagery and small preliminary analysis through my Twitter account.

Journalists increasingly found me, and I started to get quoted and interviewed by websites, printed news media, TV stations and radio stations in the Netherlands, Germany, the UK and the USA. I even appeared in a PBS documentary, being interviewed by Miles O'Brien about an analysis of North Korean launch imagery.

with Miles O'Brien for a PBS documentary, December 2017 (aired in February 2018)

When I started this blog 15 years ago, I never dreamt it would take off this way. It has been a surprising journey: starting as a rank amateur 15 years ago, I am now, partly thanks to this blog, actually employed as a Space Situational Awareness (SSA) consultant at Leiden University in a project with the Space Security Center of the Royal Dutch Air Force. It goes to show how things that start small and simple, over time can grow very serious.

The shift towards more professional SSA involvement was the result of a terrible tragedy. On 17 July 2014, a Malaysian Airlines airliner, flight MH17 flying from Amsterdam to Kuala Lumpur, was shot down over Ukraine. 298 people lost their lives, including 192 Dutch. For me this tragedy was extra unnerving at the time, as my girlfriend and I were about to fly the same route with KLM/Malaysian only three days later...

I wrote a blog post about the tragedy (the first of several) detailing how Space-based data from the classified SBIRS satellite constellation and various SIGINT satellites might shed light on where, and by inference by whom, the missile was launched.

This blog-post was subsequently picked up by a Dutch Member of Parliament, Pieter Omtzigt, who then contacted me. He used the information I provided as a base for questions in a Parliamentary committee session in 2015, and next invited me to give expert testimony in a Hearing of the Permanent Committee of Foreign Affairs of Dutch Parliament on 22 January 2016. It was part of a large, a day long session that included Radar experts, hotshots from Air Traffic Control, the Intelligence Services, and experts in international Law. I had to write a position paper for it, and during the session, give a brief presentation and then answer questions by Parliament members.

Giving testimony at a Permanent Foreign Affairs Committee hearing on MH17, 22 January 2016

This caught the attention of  the then brand new Space Security Center of the Royal Dutch Air Force, who contacted me a few days after the hearing. They were very interested in what I was doing, especially since they wanted to create their own tracking capacity. This led to several meetings and eventually two projects, one completed and one currently running. The astronomy department of Leiden University hired me as a consultant as part of these projects. What started as a hobby, turned professional (this has happened to me before by the way: with meteorite research. That started as a hobby too but led to a research job at the Dutch National Museum of Natural History, and a 30-page scientific paper in Meteoritics & Planetary Science).

Those who have followed this blog for several years, know that the content is ecclectic (mirroring my wide interests). Apart from imagery and analysis of classified satellites, it also features posts on missiles, and occasionally features more off-topic subjects such as meteoric fireballs, meteorites, comets and asteroids.

This reflects my wide and varied interests, which is apparent in much of what I do. I am a scientist with a PhD in Palaeolithic archaeology, but I have worked as a scientific researcher in totally different fields too, including Planetary Geology/Meteoritics and now also SSA.

So that is the story of how this blog came into being, and how it changed my life.

What were some of the highlights of those 15 years writing this blog and doing OSINT analysis on classified space and missiles? Among the more notable for me were:

The shootdown of the malfunctioned spy satellite USA 193 in 2008: the first time my blog started to gather a large audience I think;

The uncontrolled reentry of the Japanese spy satellite IGS 1B (resulting in several visits to my blog by the Executive Office of the US President);

The uncontrolled reentry of GOCE, my entry into reentry modelling;

The launch window analysis of North Korea's Kwangmyŏngsŏng-4 satellite;

The posts that lead to my involement in the MH17 case (and ultimately to my current job);

The analysis of North Korean Ballistic Missile launch imagery (here, here, here , here, here, and here a.o.), and the subsequent interview with Miles O'Brien;

The analysis of amateur observations of the SIGINT satellites PAN/NEMESIS 1 and MENTOR 4 in the context of leaked Snowden files, leading to a publication in The Space Review;

The analysis of the close flyby of the ISS by a US spy satelllite, USA 276, leading to a publication in The Space Review;

The analysis of a Trident-II SLBM test captured by chance on photograph by an amateur astronomer from La Palma, in the context of other Atlantic Trident tests;

The uncontrolled reentry of Tiangong 1 (which saw me on radio in the UK and USA);

The analysis of an Indian ASAT test, leading to a publication in The Diplomat;

The analysis of a (de-)classified KH-11 image from a tweet by Donald Trump;

The observation of the first Starlink train in May 2019 (with a video that went viral and has now been watched over 1.8 million times)

It has been a long (and fun!) ride: and it ain't over yet! Here is to fifteen more years of the SatTrackCam (b)log!

Wednesday, 5 August 2020

NROL-129 payloads located on-orbit

click image to enlarge

On July 15, 2020, at 13:46 UT, the NRO launched NROL-129 from the Mid-Atlantic Regional Spaceport at Wallops, using a Minotaur IV rocket (a modified Peacekeeper ICBM). This launch delivered four Classified payloads to Low Earth Orbit: USA 305, USA 306, USA 307 and USA 308.

The payloads and the Orion 38 Minotaur upper stage were located on orbit by amateur trackers last week. They are in 54-degree inclined, ~570 x 580 km orbits (see image above).

The payloads are bright, reaching magnitude +3 (naked eye) on a good pass. A fifth object which we believe to be the Minotaur's Orion 38 upper stage is about 2 magnitudes fainter and variable in brightness.

The images below, which I made in evening twilight of August 3 with a Canon EOS 80D and EF 2.5/50 mm lens, show two of the four payloads, USA 307 and USA 308, crossing Corona Borealis about a minute behind each other:

click image to enlarge

click image to enlarge

The four payloads seem to be grouped in two pairs, the two objects in each pair about 1 minute apart in pass-time at zenith. The two groups itself are about 8 minutes separated. We'll have to see what happens with the payload configuration over the next few weeks, but satellites operating in close pairs suggest to me that NROL-129 might be a SIGINT mission aimed at geolocating radio signals, similar to the French ESSAIM constellation.

The two payload pairs might be represented by the two mission patches (first two patches below), one showing a male warrior, the other a female warrior. Or maybe they represent the satellites making up each pair instead, as in a 'couple'.

The launch patch (third patch below) shows the Minotaur logo, and four stars in top which might represent the four payloads. In addition, it shows 7 stars at the left side, which probably represent that this was the 7th Minotaur IV launch. The single star at lower right might symbolize that this launch was the first Minotaur IV launch for the NRO.

The image below shows the position of the four objects when the orbits are propagated backwards to a few minutes after launch. The position and track matches a launch from Wallops well:

The moment of payload separation is unknown, but media sources suggest this was after a prolonged coasting phase. A coincidence analysis that I performed is hampered by the fact that the payloads probably manoeuvered several times, but does suggest that payload separation was somewhere between 14:10 and 14:40 UT, near the first apogee pass in the southern apex of the orbit. As Ted Molczan noted, release was probably in two directions (the upper stage rotating 180 degrees inbetween releasing the D/E and A/B pair)) to create the two pairs, the D and E objects released first, and then the A and B objects.

The video below is a compilation of 5 video segments I shot over 10 minutes near local midnight of 2/3 August, showing the objects pass in order of appearance: USA 305, USA 306, the Orion 38 Minotaur R/B, USA 307 and USA 308:

The first observation of one of the payloads, as a UNID, was done by Russell Eberst in Scotland on 27 July. Ted Molczan first suggested it was one of the NROL-129 payloads. A new observation of two of the objects was done by Leo Barhorst in Germany on July 29. One night later, Cees Bassa in the Netherlands performed a planar search and observed all five objects. I followed with observations the next night, and have now imaged them a couple of times.

A sixth object was initially reported by Cees Bassa. It was very faint and seen only once. It appeared to be in a somewhat differently inclined orbit than the other objects. It was not seen during later plane searches, including a plane search by me. We now believe this mystery object to be a chance sighting of a cubesat unrelated to the NROL-129 launch.

Sunday, 12 July 2020

OT: Comet C/2020 F3 NEOWISE

click to enlarge
The image above shows comet C/2020 F3 NEOWISE, which is currently visible low on the northern horizon after sunset and before sunrise. From my 51 degree latitude, it is circumpolar, so visible all night, although very low in the sky. For the Northern hemipshere, this is probably the best comet since Hale-Bopp in 1997.

I took the image (or rather: images, as it is an image stack) last night around 00:58 UT (2:58 CEST) from Polderpark Cronesteyn on the outskirts of Leiden. It is a stack of 45 images of 0.6s exposure eacht, at ISO's 1600 and 4000, taken with a Canon EOS 80D + Samyang 2.0/135 mm on a fixed tripod (i.e. no tracking). The comet was only 8 degrees above the N-NE horizon at that time.

Apart from the bright bent yellowish dust tail, a hint of the straight, faint blue ion (gas) tail can be seen.

It was a very nice night (with owls calling), but a bit moist, with a carpet of low fog over the meadows. I had an USB dew lint and USB battery with me, and was glad I did. My glasses fogged over at times.

The comet is visible with the naked eye (even from my urban environment) with a few degrees of tail. It is impressive in 10 x 50 binoculars. the brightness is somewhere around magnitude +2.

The 2.0/135 mm Samyang turned out to be a superb lens for this comet, by the way. I am surprised by what I can achieve with it on this comet without a tracking mount.

Saturday, 4 July 2020

ISS Debris Avoidance Manoeuvre of 3 July 2020

click to enlarge

ROSCOSMOS has announced that the International Space Station (ISS) had to make an unscheduled orbit adjustment (a debris avoidance manoeuvre)  at 18:53 Moscow Time (15:53 UT) on July 3, in order to dodge a piece of space debris. The rocket engine of the Progress MS-14 cargoship attached to the ISS were used for the manoeuvre, burning 100 seconds giving the ISS a delta V of 0.5 m/s. The ISS orbit was raised by about 900 meters as a result.

The brief bulletin did not identify which piece of space debris was dodged. Using COLA, I could however identify it as object 27923 (1987-079AG), a piece of debris from the Russian Proton rocket that launched the Kosmos 1883 GLONASS satellite on 16 September 1987.

One of the rocket stages from this launch shed some 31 pieces of debris in 2003, most of which decayed rapidly. The object that necessitated the July 3 ISS manoeuvre is one of the larger, and one of the few remaining shed pieces on-orbit. It is is a very eccentric, 350 x 4454 km, 64.9 degree inclined orbit (it's apogee has come down considerably over the past 17 years, from almost 20 000 km in 2003). The CSpOC catalogue characterizes its size as 'medium' (i.e. an RCS of 0.1 - 1.0 m2).

Had the ISS not changed it's orbit, this piece of space debris would have made a pass to a nominal distance of ~0.5 km at 18:28:19.07 UT on July 3. Note that this is a nominal value based on two TLE's: so there is a possible error of 1-2 km. But it is clear that this larger piece of debris would have passed well within the 4 x 4 x 10 km safety box around the ISS, necessitating the debris avoidance manoeuvre.

COLA output:

DATE       UT            RANGE   dALT    ANGLE
3 Jul 2020 18:28:09.07   0.5     0.1     107.1

The encounter would have occurred at 436 km altitude over the south Atlantic some 600 km northeast of the Falklands, near 48.1 S,  51.7 W (see illustration above and movie below).

ISS debris avoidance manoeuvres like this are not very frequent: it happens maybe once per 1-2 years.

Saturday, 13 June 2020

A French M51 SLBM test with a 6000 km range on June 12

click image to enlarge

On the morning of June 12, 2020, the French Navy test launched an unarmed M51 SLBM from the Triomphant-class submarine Le Téméraire.

The launch was from a spot near the French coast just south of Audierne Bay in Bretagne, not far from the French Naval port of Brest, according to a French Government bulletin. Navigational Warnings place it around 47o.65 N, 4o.15 W. The launch direction was towards the Caribean, with impact in the Atlantic Ocean near 24o.4 N, 66o.1 W according to the same Navigational Warnings.

The locations of the hazard areas from these Navigational Warnings point to a 6000 km flight trajectory (see figures above and below):


DNC 08.
A. 47-12N 010-25W, 47-49N 004-31W,
47-39N 004-01W, 47-24N 004-11W,
46-44N 010-17W.
B. 46-17N 019-54W, 46-50N 017-09W,
45-07N 016-29W, 44-35N 019-01W.
2. CANCEL THIS MSG 111200Z JUL 20.//

Authority: NAVAREA II 167/20 042002Z JUN 20.

Date: 060713Z JUN 20
Cancel: 11120000 Jul 20



39-37N 040-14W, 40-40N 037-48W,
39-41N 037-07W, 38-39N 039-31W.
B. IN AREA WITHIN 92 MILES OF 24-24N 066-06W.
2. CANCEL THIS MSG 111200Z JUL 20.//

Authority: AVURNAV BREST 070808Z JUN 20.

Date: 070851Z JUN 20
Cancel: 11120000 Jul 20

I have plotted the Navigational Warnings on the map below. The line shown is a simple STK-modelled ballistic trajectory, which fits these area's well. Assuming a 1200 km apogee, the flight-time should have been around 23 minutes.

Click map to enlarge

The M51 is  the newest French SLBM. It is in service since mid-2010. It has three stages and can carry up to 10 RV's. It's maximum range is said to be near 11 000 km, i.e. comparable to the Trident-II SLBM of the US Navy and Royal British Navy. This is the 5th succesful test of an M51 SLBM (a 6th test attempt in May 2013 ended in failure).

A nice summary of what is known from public sources about this test is provided in this article by Tyler Rogoway on The Drive.

Note added
For those interested in these issues: last year, I did an in-depth analysis of several Trident-II SLBM test launches, including one that was serendipitously photographed by an astrophotographer from the Canary Island. The latter observation allowed to estimate the apogee altitude of that test.

Thursday, 11 June 2020

SkyTrack: a simple tool to calculate satellite positions and visuallize satellite trajectories in Google Earth

Over the past years I have written a number of simple software tools to ease some of my data analysis. Some of these I have released into the wild through my software webpage. Others, which are more experimental, I keep to myself for now.

This week I have released another tool into the wild: SkyTrack.

SkyTrack (now in version 2.5) was initially written by me to quickly create a datafile with geographic coordinates of the trajectory of a satellite, in a format that is easy to import in QGIS, the mapping application that I use to make the trajectory maps that you frequently see in my blog posts.

It has since evolved and is starting to get to a point where it might be useful to others, hence why I release it now.

The output of the program is numerical (a table with data), not graphical, which will limit the usefulness to many people. However, as of the latest version (2.5) the program has the option to generate a .kml file of the trajectory for import in Google Earth (if Google Earth is installed on your pc, it will actually auto-open it and load the .kml, after saving).

When the .kml is loaded into Google Earth, the resulting images look like this:

The program takes lines 1 and 2 of a TLE as input (you copy/paste them into the input textbox). You then provide it with a time window, a desired time step, and an observing site.

It will then calculate the ground-track (the subsatellite-point) over that time window, in the given time steps; it will also calculate the altitude above the Earth at each time instance; the range to the observing site and the satellite's position in both RA/DEC and azimuth/elevation as seen from the observing site. It will also provide an indication whether the satellite is sun-illuminated at each time instance

As optional output, the program can add EFG (ECEF) X, Y, Z coordinates, as well as the EFG velocity vector. It can also calculate the Doppler-shift corrected radio frequency for the satellite, if a center frequency is given.

There are also options to restrict the program to only provide output when the satellite is a specified distance in degrees above the horizon as seen from the observing site, and/or only provide output when the satellite is sun-illuminated.

There are a number of options as well regarding the output format. A pdf with the download provides instructions for use.

The program is currently only available for 64-bits Windows. It employs Microsoft's .NET framework, and SGP4 DLL's that are courtesy of the US AFSPC.

For the future, I want to add some direct graphical output options, but it might take a while before I get to that. So far, development of this tool was largely done when the need for a specific feature arose.

Wednesday, 3 June 2020

Introducing a new web resource: Launchtower

Before new launches, I frequently publish orbital element (TLE) estimates that can help satellite observers plan observations of the payload and/or associated rocket stage directly after launch.

Untill now, I published these pre-launch estimated TLE's on the SeeSat-L Mailing List and occasionally also on this blog. And I will keep doing that: but I realized that it would perhaps be good to have a central website for these pre-flight TLE's.

So I introduce to you: Launchtower (

The TLE estimates in question are based on public information about the launch site, launch date and launch time, and (if made public) the orbital altitude and orbital inclination aimed for.

For classified launches (where this information usually is not available), educated guesses are made based on amongst others information gleaned from NOTAM's and Navigational Warnings. These provide information on launch time windows, and the orbital inclination aimed for, which can often be deduced from the launch azimuth, which in turn can be deduced from the locations of the launch hazard areas and upper stage deorbit areas found in Navigational Warnings.

The website will provide TLE estimates for launches that are "of interest". The criteria for what comprises "of interest" are basically:  those launches that are of interest to me.

Generally speaking, these will be: classified launches; human spaceflight; and launches that overfly Europe on the initial revolution.

TLE's can be used to plot a sky track for your location, using predictive software like for example HeavenSat.


On request, I have added a plain-text file URL as well, to which you can point software that can (stupidly) only load TLE's from plain text files on a web-adres. Link is on the main Launchtower page.

Sunday, 31 May 2020

Imaging a pass of the Crew Dragon Demo-2, and a close fly-by of the Crew Dragon by USA 245! [UPDATED]

click photograph to enlarge

Yesterday May 30 at 19:22 UT finally saw the launch of the SpaceX Crew Dragon Demo-2 with astronauts Hurley and Behnken on board, returning a human spaceflight capability to the USA after nine years of having to hitch rides on a Russian Soyuz.

When the Crew Dragon first passed over the Netherlands some 23 minutes after launch (see map with the launch trajectory in  a previous post), the sun was still just above the horizon for my Leiden location. I nevertheless tried with binoculars, using the moon as a guide, but saw nothing.

But two hours after launch on the second revolution, near 21:18 UT, we did have a visible pass, albeit in late twilight and very low above the horizon: at a maximum elevation of only 9 degrees over the horizon and a range of almost 1200 km!

To observe this pass I went by bicycle to Cronesteyn Polder at the edge of Leiden, where I have an uninterupted view to the horizon, and set up my photo camera. First, at 23:14 local time (21:14 UT), I saw the ISS pass with the naked eye low on the southwest horizon. I then took to binoculars and waited for the Crew Dragon, which should pass somewhat lower in the sky some 4 minutes after the ISS.

I picked the Crew Dragon up in my 10 x 50 binoculars starting around 21:17:30 UT, while it was passing through Crater and Corvus. I watched it untill it entered Earth shadow at about 21:19:00 UT. It was not particularly bright, due to the low elevation and still bright sky background. By comparison to stars in Corvus I estimate it to have been magnitude +3 to +3.5, too faint at this elevation and with this sky brightness to be seen naked eye. It was at a range of almost 1200 km at that time, over Northern Spain!

Click photograph to enlarge

The image above shows the Crew Dragon during this pass. It is a stack of 45 exposures of 0.5 seconds each, with a Canon EOS 80D and SamYang 1.4/85 mm lens at F2.0, 500 ISO, 21:17:40 - 21:18:09 UT (May 30). Stars in the image belong to the constellations Crater and Corvus. The small breaks in the trail are the brief moments between the successive photographs that make up the stack.

The image below is another stack, this time of 52 photographs with the same camera setup, made between 21:18:25 - 21:18:59 UT. You see the Crew Dragon disappear in Earth shadow at the left end of the image. The image is slightly wobbly - my tripod was on a soft grassy surface. I like this image best though:

Click photograph to enlarge

It was pretty cool seeing the Crew Dragon, while knowing it was carrying two astronauts!

But it becomes even more interesting: in two images around 21:18:19 UT, I have another brighter satellite moving under a slant upwards in the opposite direction. You can see it in the upper right corner of this image (several lay observers saw this brighter satellite too and mistook it for the Crew Dragon):

Click photograph to enlarge

This object is the classified US KH-11 spy satellite USA 245 (2013-043A).

And as it turns out, it was really close to the Crew Dragon, and my image truely captures, within a few seconds, the actual moment of closest approach! This was serendipity, as I had not planned this and the presence of USA 245 took me by surprise.

Nominally, the minimum distance between USA 245 and the Crew Dragon during this fly-by was only 125 km with closest approach happening at 21:18:17 UT. USA 245 was flying this distance 'above' the Crew Dragon. Both objects were over northern Spain around the time of the flyby, with the point of closest approach over 43.40 N, 2.50 W, on the Basque coast.

There is some uncertainty in the actual fly-by distance (see below), but not much.

This is the output from a COLA analysis for this fly-by:

DATE      UT          SSC   NAME    TARGET      KM  
5/30/2020 21:18:16.99 39232 USA 245 CREW DRAGON 125.3

My analysis is based on CSpOC elset epoch 20151.85044152 for the Crew Dragon, and amateur elset 20146.86101776 for USA 245. There is some leeway in the exact time and distance of the flyby, for two reasons:

1)  from my observations, the Crew Dragon was some 3 seconds late on the used elset;

2)  the USA 245 elset epoch, based on amateur observations that include my own, was 5 days old. However, the sky position of USA 245 in the image is very close to the ephemeris, so the 5-day-old orbit nevertheless seems a good fit to reality.

Taking these points into account, I estimate that the uncertainty in the minimum distance between both objects is no more than 30 km, and only a few seconds in time.

In the map below, I have plotted the trajectories of both objects (I have accounted for the fact that the Crew Dragon was ~3 seconds behind on the elset in this map). USA 245 was moving nortwest-wards, the Crew Dragon southeast-wards.

Note that the USA 245 trajectory was situated some 125 km above that of the Crew Dragon. So to be clear, there was no danger of a collision. This is a safe distance.

click map to enlarge

 This is an animation of the close fly-by:

In fact, it could very well be that this close flyby was intentional, and that USA 245 was actually imaging the Crew Dragon at that moment.

USA 245 is a KH-11 electro-optical reconnaissance satellite: a satellite that resembles the Hubble Space Telescope and makes high resolution images of the earth surface (similar to this infamous one) with resolutions of 10 cm or better.

There have long been rumors, reported by amongst others NBC News, that KH-11 satellites were used to inspect the outside of Space Shuttles post-launch (e.g. that of the inaugural STS-1 flight) for tile damage. We also suspect that KH-11 satellites inspect X-37B's after launch, based on the odd jumps in launch times of the latter (see this analysis by Bob Christy).

So there is a real possibility that this close flyby of the Crew Dragon by USA 245 was intentional, and used to image the spacecraft to see if it was not damaged and everything deployed as it should.

UPDATE 1 June 2020 13:50 UT:

I am retracting the notion of intentionality of this encounter. Both Michael Thompson and I have done an extended analysis of potential KH-11 encounters with the Crew Dragon, where we looked at potential encounters had the Crew Dragon launched on the original launch date of 27 May.

There appear to have been no particularly close encounters would the Crew Dragon have launched on May 27, which calls into question the intentionality of the encounter on May 30.

That said: it is still possible that imaging of the Crew Dragon took place, as of course this would have been a perfect opportunity. I guess we'll never know. Unless, as someone put it to me in private, tongue in cheeck: "if they put it in a briefing, maybe Trump will tweet about it!". 

The analysis also found a second close encounter for May 30, with the KH-11 satellite USA 224 (2011-002A), on 30 May 20:07:50 UT, some 45 minutes (half a revolution) after launch, with a nominal miss distance of 105 km. This however was a pass where the Crew Dragon was in Earth shadow, so not illuminated (which does not preclude infra-red imaging however). COLA output for this encounter:

DATE      UT          SSC   NAME    TARGET      KM 
5/30/2020 20:07:50.30 37348 USA 224 Crew Dragon 105.4