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

Saturday, 30 May 2020

New attempt to launch the Crew Dragon on May 30: trajectory

screenshot from the May 27 live webcast

In an earlier post I discussed the SpaceX Crew Dragon Demo-2 launch. Originally slated for 27 May, it was postponed (with the astronauts already seated on board) because of bad weather: Tropical Storm Bertha more north on the US coast was the main culprit.

The new launch attempt will be on May 30 at about 19:22:45 UT (the subminute time comes from Spaceflight Now, not from an official SpaceX or NASA source, so is apocryphal). If that launch is scrapped to, the third backup date is May 31 near 18:59 UT.

As things currently (29 May 21:00 UT) stand, weather prospects are not that good for both these dates either, with currently a 50% chance of a weather violation on the 30th and 40% on the 31st: so perhaps we will see a scrub again.

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But in case the launch does happen on 30 May, the map above is the trajectory the Crew Dragon will fly on its first revolution (times on the map are in UT).

Some 23 minutes after launch, the Crew Dragon will pass over Europe, along this trajectory (times are inUT: add one hour to get BST and 2 hours to get CEST):

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Note the location of the day/night terminator...only eastern and southeastern Europe has sufficiently dark skies at that moment.

The launch time has shifted considerably forward compared to the May 27 original launch date, by about 1h 10m. As a result, the pass is no longer favourable for NW Europa, as the pass will be before sunset for the UK, and around sunset for coastal Europe.

Only longitudes east of say longitude 13 deg E will have a sufficiently dark sky to see it on the first revolution, so eastern and southeast Europe will have a prime seat this time.

Coastal western Europe and the UK might have, depending on your locality, a theoretical chance to see the second pass 1.5 hours later, near 21:18 UT. For most localities, that will however be a very low elevation pass though, often at a maximum elevation of les sthan 10 degrees.

At the end of this blogpost, I will provide some sky charts for several European localities for both those localities with a chance to see something of the first pass, and those who might theoretically catch the second pass.

The reason that the launch time is 1h 10m earlier on May 30 than on May 27, is that the launch time is instantanious as it is determined by the moment that the orbital plane of the ISS passes over the launch site. This time shifts back by 23m 22s each day, as is clear from this tabel in which I calculated orbital plane crossings over LC-39A (and is visualized in the illustrations below it):

ISS plane crossing over LC-39A:
Date           UT   
27 May         20:36:52
28 May         20:13:30
29 May         19:50:09
30 May         19:26:47
31 May         19:03:26


You can also see in the table that the actual launch time is a few minutes before the plane crossing. This has two main reasons.

One is that what is actually of relevance is the position of the orbital plane once the rocket reaches orbital height (a few minutes after launch).

The other is that the Crew Dragon initially is inserted into a ~200 km altitude orbit, which is only half the orbital altitude of the ISS. As a result, the Precession rate of the RAAN is faster than that of the ISS: so launch has to be somewhat earlier or otherwise, over the 19 hour flight, its RAAN would overshoot rather than match that of the ISS upon arrrival at the orbital altitude of the ISS.

The reason May 28 and May 29 were not chosen as backup dates, is because of a second consideration: the ISS has to be within a certain distance window to the launch site in order for the two (Crew Dragon and ISS) to meet up after 19 hours of flight. As it happens, and I am not sure that is deliberate or just a happy coincidence, this also means that on the chosen dates, docking will happen on the night-time side of the Earth (with launch on May 28 or 29 it would have happened on the daytime-side).

Below are a number of sky maps for localities that have a dark enough sky (generally: sun no less than 5 degrees below the horizon) to see the first pass, some 25 minutes (for eastern Europe) after launch near 21:46 CEST. Note that there is a time uncertainty of about 1 minute or so.

TLE's are provided below the maps.

NOTE: if you are not near one of these localities, then Heavens-Above provides you with predictions for your custom location. Please note however that Heavens-Above predictions for the second revolution (the 23:19 CEST pass over Europe) seem to be based on the TLE for the first revolution, resulting in a time difference of about 1 minute with my predictions below.(but also realise there is an uncertainty of 1-2 minutes in the estuimated orbit anyway).

Maps for locations in NW Europe might theoretically be able to see the Crew Dragon on its second revolution, near 23:18 CEST (22:18 BST), some 2 hours after launch. But in most cases this will be very low above the horizon. Please note that the time uncertainty is 1-2 minutes at least!

Here is an estimated TLE for the first revolution:

CREW DRAGON                                      initial orbit
1 70000U 20999A   20151.80474535 -.00003603  11390-4  00000+0 0    04
2 70000  51.6423 075.0039 0122953  45.6251 315.4951 15.99554646    01

And here is an estimated TLE for the second revolution:

CREW DRAGON                                      second revolution
1 70001U 20999A   20151.93029831 -.18507952  12289+0 -23808-1 0    05
2 70001  51.6233 074.5097 0096856  46.3995 314.2887 15.95177824    03

Tuesday, 26 May 2020

Imaging some splendid passes of HTV-9 (Kounotori-9) and Cygnus NG-13

It are very busy times at the International Space Station. Spaceships come and go.

First, on May 11, the US cargoship Cygnus NG-13 was released from the ISS, three months after berthing to it. This cargoship had been launched on 15 February 2020 and berthed on 18 February. After its release from the ISS two weeks ago, it is currently free-flying to do experiments. It will perform a controlled reentry over the southern Pacific on 29 May.

On 20 May at 17:31 UT, the Japanese cargoship HTV-9 (Kounotori-9) was launched. It berthed to the ISS on 25 May. This provided the opportunity to see two ISS cargoships, one departing and one arriving, in the sky last week.

And it continues: we are in anticipation of the Crew Dragon Demo-2 launch, on May 27 if weather cooperates (see my previous blogpost), bringing to astronauts to the ISS.

Both Cygnus NG-13 and HTV-9 made some splendid evening passes last week. Weather was clear on most days, allowing me to observe and photograph several passes, often two on one evening. Through Twitter, I managed to get a lot of people to go out and watch the passes. HTV's are very bright and distinctly orange objects, easily visible with the naked eye even in deep twilight and from an urban environment. So they are ideal objects to get people out and watch.

HTV-9 was a spectacular sight on every pass. It reached magnitude 0 to -1, with a very distinct orange colour that is due to the orange thermal foil it is wrapped in. It was also prone to producing brief bright flares to magnitude -2 to -3. It did this on almost every pass, sometimes multiple times. here is an example, from May 21:

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Below are a number of photographic stacks I made during these HTV-9 passes (gaps in the trails are the brief periods between successive photographs in the stack). The first image showing another flare: the second bright satellite crossing the path of HTV-9 in the third image is Resurs P1. Note the orange colour, especially apparent in the second image. Visually, the orange colour was even more profound than in these images (where they have washed out a bit due to the brightness of the trail).

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Cygnus NG-13 was much fainter than HTV-9. During a  good pass it would reach magntude +3, but often was below naked eye visibility. Here is imagery from one of the brighter passes, on May 19 when it reached magnitude +3:

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