Wednesday, 18 May 2022

Kosmos 482: questions around a failed Venera lander from 1972 still orbiting Earth (but not for long)

I have just published a new article in The Space Review. It is freely accessible here.

It is titled "Kosmos 482: questions around a failed Venera lander from 1972 still orbiting Earth (but not for long)".

It is an in-depth look at the recent controversy surrounding 1972-023E, the Kosmos 482 Descent Craft, a piece of hardware from a 1972 Soviet era Venera mission to Venus that failed and got stuck in Earth Orbit.

In it, I think I can conclusively answer several questions around this object, including that it is the 'descent craft' in its protective spherical shell only, rather than a substantial larger piece of Venera hardware as thought by some.

The article includes evidence from my own observations (photometry); comparisons of actual orbital evolution with long-term orbital simulations with the General Mission Analysis Tool (GMAT) for various objects associated to this launch; as well as radar cross sections published by CSpOC and LeoLabs. I also provide a new reentry forecast for 1972-023E

Read the article here on the website of The Space Review

Wednesday, 20 April 2022

USA 327 / NROL-85

The video above which I shot yesterday evening (19 April 2022) shows USA 327, the NROL-85 payload, passing over my home in Leiden, slightly over two days after it was launched. The footage was shot with a WATEC 902H2 Supreme Low Light Level CCTV camera with a Canon FD 1.8/50 mm lens fitted.

NROL-85 (see two previous posts about this very recent classified launch here and here) has now been catalogued (with orbital elements witheld) by CSpOC as USA 327, catalogue nr 52259, COSPAR ID 2022-040A. Only one object was catalogued, there was no spoof second 'debris' object entered.

As already mentioned in a recent post, the fact that there is no second object is a big surprise. We expected NROL-85 to deliver two payloads, a pair of INTRUDER (also known as NOSS, which stands for Naval Ocean Surveillance System), SIGINT satellites used for geolocating shipping on the High Seas by means of time difference of arrival of their radar/radio emmisions.

Before 2001, NOSS systems existed of three co-orbiting satellites forming a thight triangular formation. From 2001 onwards (with the launch of NOSS 3-1, the first of the Block 3 NOSS-es) , this changed into two co-orbitting satellites.

(the video below, from 30 August 2018, shows a typical NOSS pair, in this case both briefly flaring due to a favourable sun-satellite-observer angle on some reflecting part of the satellites. While operational, NOSS pairs always move this close together. The NOSS pair in question is  NOSS 3-6, the same NOSS pair into which orbital plane the new USA 327 satellite was launched).

And now, we have only one, not two, satellite launched in a NOSS-like orbit. Analysts are scratching their heads over this.

Given the strong similarity in orbit, and the fact that it was launched into the orbital plane of an existing 10-year-old NOSS pair (see previous post), NOSS 3-6 (2012-048A & P), there is clearly some conceptual link of the new satellite to the NOSS program

But in what way exactly? There are a couple of options:

(1) This is a new generation of NOSS/INTRUDER, (i.e. NOSS block 4-1), that needs only one satellite;

(2) This is something else, something new, but related to NOSS/INTRUDER;

(3) This was meant to be NOSS 3-9, a regular NOSS pair, but something went wrong and the second satellite was not deployed;

(4) There is a second satellite but it is small (cubesat) and not yet detected;

(5) The second satellite still has to detach from the first


So let us briefly comment on these various options:

Option (1) apparently, is feasible, according to some. Apparently it is possible to do TDA using just one satellite

With regard to option (2), the most interesting one, one could think of for example an optical or radar counterpart to the existing NOSS 3-6 SIGINT pair: one that images the ships geolocated by NOSS 3-6. This makes sense (and it also makes sense that the new satellite orbits half an orbit apart from the NOSS pair).

While we cannot exclude option (3), I think it is not the most likely option. The same goes for option (5): with previous NOSS launches, two objects were detected right after launch. I have no opinion on option (4).

If we look at the current orbit of USA 327 and the orbit of the NOSS 3-6 pair, we note that: 

(a) they move in almost the same orbital plane; 

(b) they currently are almost exactly half an orbital revolution apart (see illustration below); 

(c) because of the latter difference in Mean Anomaly, their ground tracks are not the same but have some distance between them.


click map to enlarge

Observation (c) does not entirely make sense to me. Wouldn't you want your imaging satellite to follow the same ground track as the geolocating SIGINT satellites? On the other hand: true: the footprints are large enough to cover a large overlap in ocean space from both groundtracks. But still....

Another aspect of this that does not completely make sense to me is that, if USA 327 is a technology demonstrator for a new complementary IMINT mode to the NOSS SIGINT system, then why pick a 10-year-old, nearly retired pair of NOSS satellites to test it with? Why not pick a fresher pair, so you can happily experiment away for the time to come?

But maybe, those fresher pairs of NOSS satellites are deemed more suited for when, after this technology demonstration, the truely operational system is deployed. But then again, why bother with that, just replace the technology demonstrator with the operational version and deorbit the technology demonstrator.

Questions, so many questions, and my still post-COVID impaired brain cannot make much sense of it yet...

It will be interesting to see what USA 327 does (in terms of orbital manoeuvres etcetera) the coming months.

Meanwhile, Radio observer Scott Tilley in Canada has detected the first S-band radio signals from USA 327. He reports "huge fades in signal", which is odd. From Cees Bassa I understand that the frequency in question, 2277.5 MHz, is a know frequency used during the checkout-phase of NOSS 3-x pairs.

A surprisingly bright flare from a 6U Cubesat

​The 240 frames frame stack above, which is from the video below, shows the classified Japanese satellite IGS Optical 5 (2015-015A). But at 21:14:05.5 UT, somethings else moving nearly parallel to the satellite briefly flares up.

The flaring object in question, producing a flare of at least magnitude 0, is TYVAK 182A (also known as ELO Alpha), 2021-034D. This is a 6U cubesat. I am quite surprised to see such a bright flare from such a small object!

The video was taken from Leiden, the Netherlands, with a WATEC 902H2 Supreme fitted with a Samyang 1.4/35 mm lens.

Monday, 18 April 2022

NROL-85 observed, but is it an INTRUDER/NOSS or something else? [UPDATED]

click image to enlarge


Yesterday 17 April 2022 at 13:13 UT, SpaceX launched the classified NROL-85 mission for the NRO. Before the launch we widely expected this to be NOSS 3-9, a new pair of INTRUDER/NOSS satellites (see previous post), based on clues as to the orbit it was launched into. 

The orbital inclination and orbital altitude suggested by OSINT infornation on the mission were typical for NOSS/INTRUDER, and the time of launch indicated a launch into the orbital plane of the 10-year-old NOSS duo NOSS 3-6. That is a pattern we have seen before with NOSS missions: a replacement launched into the same orbital plane after 10 years of operational service.

So we expected to observe two objects after launch. 

But NROL-85 had a surprise in store: so far, we detected only one object, not the expected two!

This leads to the question: is NROL-85 a new INTRUDER/NOSS, or not?

NROL-85 was first picked up by me, from Leiden, the Netherlands, some 7 hours after launch, in late evening twilight of 17 April around 19:59 UT (21:59 CEST). It was some 2.5 minutes early on my pre-launch estimated search elset. I subsequently also observed it on a second pass two hours later.

On the first pass, I captured it photographically (see image in top of this post, showing it above the roof of my house along with two old unrelated rocket stages), using a Canon EOS 80D with a Samyang 1.4/35 mm wide angle lens (the exposure is a 2-second exposure at ISO 800). The video system I had set up captured it too, but only very briefly in a corner of the field of view. Only one object was seen, nothwithstanding that I did a photographic plane scan during quite some time.

The second pass was in the northern sky with a less favourable phase angle (so the object was much fainter than during the first pass). I captured it with the video system, and after following it for a minute or so, left the camera stationary to look for a possible second object. None was detected, either before or after the detected object.

Likewise, fellow observers from the Seesat-L list including David Brierley and Eelke Visser, detected only one object too. And Scott Tilley reports that he did not detect radio signals at the frequencies usually used by NOSS.

The absence of a second object could mean that NROL-85 is not a new INTRUDER/NOSS mission after all, but something else, although the orbit is very NOSS-like.

Alternatively, perhaps it is an improved version of INTRUDER that now needs only one satellite, rather than two.

NOSS missions once consisted of three satellites orbiting close together in a triangular formation. In 2001 this changed to two satellites. Maybe now they found a way to do it with one satellite?

The object we detected is in a 1021 x 1191 km, 63.5 degree inclined orbit (update: with a longer observational arc constraining the eccentricity of the orbit better, the new value is ~ 1008  x 1207 km). This orbit is close to the specifications given in a launch contract tender for NROL-85. Below is a preliminary initial elset based on a 5.5 hour observational arc:

NROL-85 (USA 327)
1 70002U 22999A   22108.04497945 0.00000000  00000-0  00000+0 0    07
2 70002  63.5043 123.5866 0114230 185.9890 173.9785 13.40421486    07

rms 0.024 deg

Elset update (20 April 2022): Below is the latest elset based on 114 observations by Cees Bassa, Eelke Visser, David Brearley, Andriy Makeyev and me over a two-day observational arc:

USA 327 (NROL-85)                                      1008 x 1207 km
1 52259U 22040A   22109.98456423 0.00000000  00000-0  00000+0 0    08
2 52259  63.4462 118.5572 0132890 178.9713 181.1610 13.40467640    01

rms 0.011 deg    arc Apr 17.83 UT - Apr 20.01 UT


click to enlarge

As a final note: the post-deorbit-burn fuel vent by the Falcon 9 upper stage used for the launch of NROL-85, which was deorbitted over the Pacific Ocean at the end of the first revolution (see map in previous post), was seen and filmed from Hawaii, showing the characteristic spiral shape:


(a follow-up post is here)

Tuesday, 12 April 2022

NROL-85: probably NOSS 3-9, a new pair of INTRUDER Naval SIGINT satellites


image: Wikipedia

 EDIT (15 & 16 Apr):  the launch of NROL-85 has been postponed by at least two days, 'due to technical difficulties'

EDIT (17 Apr): new launch date is 17 April 2022 13:13 UT

On 15 April 2022, at 13:41 UT (or later) according to a tweet by the NRO, SpaceX will launch NROL-85 for the National Reconnaissance Office (NRO). The launch will be from SLC-4E at Vandenberg SFB. [edit 16 Apr: launch was postponed to 17 April 13:13 UT]

NROL-85 is almost certainly a pair of NOSS satellites. NOSS stands for Naval Ocean Surveillance System; they are also known under the code name INTRUDER. If correct, the duo would become NOSS 3-9 (the 9th mission of block III). It will probably enter with the designation USA 327 in the CSpOC catalogue (with orbital elements witheld).

NOSS satellites are SIGINT satellites operated by the US Navy. They geolocate shipping on the high seas, by detecting their radio/radar emissions. They always operate in close pairs. The secondary object is usually listed (with orbital elements witheld) as "debris" in the CSpOC catalogue, but this is a ruse that fools nobody: it is a payload too that manoeuvres and keeps a careful constant close distance to the primary satellite.

Information from the launch contract tender for this launch reveals that the mission aims for a semi-major axis of  7500.5 km, an orbital eccentricity of 0.0131, an orbital inclination of 63.535 degrees and an argument of perigee of 190 degrees (i.e. perigee almost on the equator). The listed semi-major axis and eccentricity translate to a 1024 x 1221 km orbit

The combination of the 63.5 degree orbital inclination and 1024 x 1221 km orbit strongly points to a NOSS/INTRUDER mission. These typically have an orbital inclination of 63.4 degrees and a semi-major axis of 7485 km, values close to those quoted for NROL-85. If launch is indeed at 13:13 UT on April 17, the resulting orbital plane will be very similar to that of the existing NOSS 3-6 duo (2012-048A and 2012-048P) which was launched in 2012, as can be seen in the figure below. That also lines up with a new NOSS-launch: NOSS-pairs are typically replaced after 10 years on-orbit.

The shift in launch time with date due to the two launch postponements agree with the estimated orbital altitude and orbital plane and matches the nodal precession of a typical NOSS orbital plane.

click image to enlarge


The Navigational Warnings for this launch (NAVAREA IV 336/22 NAVAREA XII 228/22 and HYDROPAC 987/22) define a launch direction towards the south-southeast, and agree with the 63.5 degree orbital inclination of the launch contract tender. 

[EDIT: The first NavWarning has been corrected: I initially copied the wrong NavWarning for this post.....]

100706Z APR 22
NAVAREA XII 228/22(18,21).
   A. 34-41N 120-38W, 34-39N 120-40W,
      34-28N 120-38W, 34-04N 120-17W,
      34-04N 120-05W, 34-19N 120-14W,
      34-39N 120-19W.
   B. 32-03N 118-53W, 32-01N 118-49W,
      30-51N 117-56W, 30-21N 117-39W,
      30-08N 117-47W, 30-11N 118-01W,
      30-32N 118-18W, 31-54N 118-53W.
2. CANCEL THIS MSG 161614Z APR 22.

100644Z APR 22
HYDROPAC 987/22(22,83).
DNC 06.
   1425Z TO 1649Z DAILY 15 AND 16 APR
   20-12S 123-30W, 19-00S 119-00W,
   33-48S 109-30W, 36-00S 114-12W.
2. CANCEL THIS MSG 161749Z APR 22.


I have mapped the hazard areas from the Navigational Warnings and the resulting launch trajectory in the map below (the times listed along the trajectory are in UT and for the updated launch date with launch at 13:13 UT (17 April):

click map to enlarge

Based on the parameters from the launch contract tender, this is my orbital estimate, valid for launch at 13:41 UT on April 15 updated for launch at 17 April 13:13 UT:

NROL-85                         for launch on 17 Apr 2022 13:13:00 UT
1 70002U 22999A   22107.55069445 0.00000000  00000-0  00000+0 0    02
2 70002  63.5350 124.8521 0131000 190.0000 291.3542 13.36458926    04


There is an uncertainty of several minutes in pass time in this elset, progressively so after more than one revolution, and some cross-track error is possible. But the elset should be good enough for a plane scan, taking a wide time window around a predicted pass. Be carefull not to misidentify the NOSS 3-6 duo as NROL-85. An elset for NOSS 3-6 can be found here.

If the eventual launch time turns out to be later than 13:13 UT, the elset above can easily be adjusted to match the new launch time using my "TLE from Proxy" software downloadable here.

The Northern hemisphere will see good, fully illuminated evening passes on the day of launch and the days after it, so prospects are good for a quick on-orbit detection after launch.

The Falcon 9 upper stage deorbit is over the southern Pacific, just after the end of the first revolution. The deorbit-burn might be visible from south and/or central Asia.

The launch patch (see top of this post) features a cat, with a tiger as its reflection. The NRO itself explains some of the symbolism in the patch in this way:

"In the NROL-85 patch, the 3 stars represent guidance, protection, and allegiance. The cat represents loyalty and devotion shared among our nation and partners. The tiger in the cat’s reflection demonstrates that while space can be challenging, a determined attitude helps NRO succeed in going"

Given that this is going to be NOSS 3-9, the 9th instance of the Block III NOSS generation, I wonder if the cat was inspired by the proverbial 'nine lives' of cats.

It is possible that a number of other small satellites will be included in this launch as a rideshare.

The NRO press kit for NROL-85 is downloadable here.

FOLLOW-UP POST HERE reporting the first observations of NROL-85 from the evening of April 17. NROL-85 might not be an INTRUDER/NOSS after all!

A SECOND FOLLOW-UP POST HERE, going a bit deeper into various speculations about what the NROL-85 payload might be.

[a small update to this post was made 13 April 2022 09:00 UT, adding a bit more background information]

[an error where I had initially copied the wrong text of a NavWarning into this post was corrected at 13 Apr 20:30 UT - many thanks to the anonymous sharp-eyed reader who noted it!] 

[updated April 15 & 16 to reflect launch postponements] 

[updated 17 Apr 8:45 UT with updated launch trajectory map and orbital plane diagram]

Friday, 25 March 2022

North Korea's Hwasong-17 ICBM: capable of (briefly) bringing warheads into orbit?

image: KCNA/RodongSinmun

According to multiple western sources and North Korea, North Korea conducted a first full-power test-flight of its new Hwasong-17 ICBM on March 24, 2022, at 5:34 UT, from Sunan close to Pyongyang.

The Hwasong-17 is the Behemoth missile that was first revealed to the outside world one-and-a-half-years-ago during the 2020 October 10 parade in Pyongyang and surprised everyone by its massive size at the time. It is North-Korea's largest, heaviest missile so far and visually looks like a Hwasong-15 on steroids.

[NOTE: some sources are now casting some doubt on the missile identity, suggesting that footage from the failed March 16 launch (see below) was used. See comment at end of post]

The test launch was confirmed by North Korean State sources which produced a written account on their KCNA and Rodong Sinmun websites, accompanied by photographs, while KCNA also broadcast a video of the test. The imagery underlines how impressive the size of the Hwasong-17 is: it is a Monster of a missile!


image KCNA/Rodong Sinmun

image KCNA/Rodong Sinmun


image KCNA/Rodong Sinmun

The video report on the test as broadcast by the North Korean State Agency KCNA is spectacular, with a glamour role for the sunglasses-clad North Korean leader Kim Jung Un (look at 3:55 to 4:05 in the video below!). It evokes shades of a Hollywood action movie trailer. 

(the actual footage of the test and test preparations starts at 3:25 in the video, after the usual bombastic introductions by news anchor Ri Chun-hee)

Earlier test flights of components of the same missile might have taken place in Februari and early March (but not on full power), according to western sources. North Korea claimed at the time that it was testing components for a reconnaisance satellite program. 

We also know that on March 16, another test flight from the same launch-site (near Sunan Airport), possibly also a Hwasong-17, failed shortly after launch at an altitude of less than 20 km.

But the March 24 test flight appears to have been successfull, as claimed by both North Korea and western sources. According to North Korean official State sources it reached an apogee at a whopping 6248.5 km altitude, with a ground range of 1090 km and a flight time of long duration (1h 7m 30s).

Western sources that independently tracked the launch mention similar ballpark values for this test: apogee "6200 km" and range "1080 km" according to the S-Korea Joint Chiefs of Staff; apogee "6000 km" and range "1100 km" according to the Japanese Government. The missile came down in front of the Japanese coast inside Japan's EEZ, at some 180 km from Cape Tappi. 

The apogee is at an extreme altitude, and this test was hence extremely lofted, as can be seen in this trajectory reconstruction I made:

click to enlarge

Looking into the necessary impulse in order to assess maximum range of the missile, I realized that the resulting nominal impulse of 7.85 km/s I reconstruct, actually means that the Hwasong-17 can achieve orbital speed. In other words: this means it is powerfull enough to, in principle, loft a payload to (low) earth orbit and get it (briefly) orbital!

Objects can complete at least one revolution around the earth if they have enough orbital velocity such that they can orbit at at least 100 km altitude (the exact value of the lower limit of orbital flight is debated: for circular orbits it might be possible at altitudes as low as 80-90 km, but it anyway strongly hinges on the drag characteristics of the object in question). The corresponding orbital speed at 100 km altitude is 7.84 km/s (for a circular orbit). The nominal impulse I get for the March 24 launch, at 7.85 km/s, matches that (in reality, it is more complex, as the missile will experience atmospheric drag during the initial phase of launch, which was not part of my reconstruction. And part of the initial impulse will be lost due to gravity pull before reaching 100 km altitude).

So in theory, this missile could briefly get an object (e.g. a warhead) in orbit around the earth, rather than on a suborbital ballistic trajectory. In case you wonder: it didn't on March 24, because it was not launched on an orbit insertion trajectory, but rather straight up.


image: KCNA/RodongSinmun

image: KCNA/Rodong Sinmun

image: KCNA/Rodong Sinmun


This was not something I had expected. But it gives a new meaning to North Korean claims from earlier this year that tests conducted then, possibly with Hwasong-17 components, where in connection to a space launch program.

They did fairly and squarely present the latest March 24 test as an ICBM  test flight though.

The launch location at 39.188 N, 125.667 E (as geolocated from the imagery by Joseph Dempsey) was on a concrete strip about 1.75 km from the main buildings of Pyongyang Sunan airport. That concrete strip is part of the Si-Li Ballistic Missile Support Facility which itself is some 2.5 km southwest of the airport:

click map to enlarge

click map to enlarge

But let's get back to the realization that this missile can apparently reach orbital speeds. This means that it - or components of it - in theory can be used for road mobile satellite launches. But it can also mean that you can briefly bring a warhead in orbit, either for a full revolution or more, or - cough - for a "fractional" orbit....

Remember the discussion of the Chinese test of a FOBS ('Fractional Orbital Bombardment System') in July last year?! See this earlier post.

I have been doing some modelling. Based on specs of an early '60-era US warhead, the W56, I modelled whether a launch of a similar warhead into a very low 100 x 105 km, 98.0 degree inclined polar orbit from Sunan, could reach the USA. 

I used the General Mission Analysis Tool for this, with the MISE90 model atmosphere and F10.7 solar flux set at 100. I modelled for a 275 kg warhead with assumed Cd 1.0 and a drag surface of ~0.15 m2 (comments on how realistic those values are, are welcome) and under the assumption that the launch vehicle does achive sufficient orbital speed to insert it in such a 100 x 105 km orbit. The modelled launch was in southern direction, taking the long but undefended southern Polar route over Antarctica, approaching the USA from the south after finishing just over half an orbital revolution. [info added later: The model is strictly for the warhead assuming release from the missile upon orbit insertion: I did not model prolonged coasting as part of a post-boost vehicle of any kind].

With the mentioned specifications, I model it to nominally come down fairly and squarely in Ohio (or any other place within the continental USA if you adjust the orbital plane launched into somewhat), as the map below in which I have plotted the modelled trajectory for the warhead shows....

click map to enlarge

So: is the development of this missile perhaps a prelude to the development of a North Korean FOBS? With a suitable warhead, it appears they could do it with this missile.

Incidentally: the flight-time of the March 24 test was similar to the on-orbit flight time needed to get from Sunan to the United States via the southern polar route. But that is likely coincidence.

Leaving FOBS aside for the moment: at any rate a missile with this power launched on a more conventional ballistic trajectory can easily reach any location within the continental United States, as well as Europe and the Pacific (but would need a working reentry vehicle of course, which is another matter). In addition to that, it means that North Korea now in theory also has a potential road-mobile reconnaisance satellite launcher in their arsenal.


image: KCNA/Rodong Sinmun

image: KCNA/Rodong Sinmun

image: KCNA/Rodong Sinmun

image: KCNA/Rodong Sinmun


Added note: some sources are now casting some doubt on the missile identity, suggesting (with arguments from image analysis) that footage from the failed March 16 launch was perhaps presented by North Korea as being from the March 24 launch. The added suggestion is that the March 24 test missile might have been a Hwasong-15, not a Hwasong-17 as North Korea is claiming.

These objections are interesting, but multiple scenario's are possible. For example, they might have used footage from both test launches, certainly if iconic scripted propaganda scenes (e.g. KJU marching in front of the TEL leading his Rocket men) were shot during the preparations for the failed March 16 test. North Korea has been known to have doctored launch imagery for aesthetic/propaganda purposes before in the past, as I have shown for the historic first Hwasong-15 launch of 28 November 2017.

Whatever missile it really was: the missile performance shown by this test is remarkable and well beyond that of earlier North Korean ICBM launches. Western tracking of the missile test confirms the performance, so it is not just North Korean propaganda that can easily be waved away. This is a significant development, no matter how you look at it.

Wednesday, 9 February 2022

This week: rainshowers with a slight chance of falling satellites

The spectacular image above is a frame from video footage obtained by cameras at AƱasco, Puerto Rico, part of a cameranetwork from the Sociedad de Astronomia del Caribe (SAC). It was shot on 7 February 2022 near 6:40 UT (2:40 local time) and shows what clearly is a satellite reentry, the reentering satellite spectacularly breaking up into many fragments.

Below is the actual video. It shows two objects appearing about 1 minute apart, both reentering and fragmenting. Especially the second object is spectacular. The two objects could belong to one object that has broken up earlier; or be two separate objects close together in the same orbital plane.


The reentering object(s) can be identified as belonging to a batch of 45 49 Starlink satellites launched on 3 February 2022, two-and a half days before the reentry sighting from Puerto Rico.

A day after the launch, when most of the deployed satellites yet had to raise their orbits, a Coronal Mass Ejection (CME) from the Sun arrived at earth, creating a geomagnetic storm

During a geomagnetic storm, the upper atmosphere warms up and expands somewhat, causing an increase in drag in low orbital altitudes. SpaceX therefore put their just launched satellites, still in a very low orbit, into safe mode and a least-drag attitude. 

This however prevented them from raising their orbits, and it did so long enough to make it impossible for some 40 of them to be rescued. Over the past days a number of them (at least three, possibly more, including the object over Puerto Rico, at time of writing (9 February 16:00 UT)) have already reentered and the other objects, some 40 in total according to SpaceX, will reenter over the coming week.

Fourty (40!) satellites reentering in only a week or so, is unique. The coming week, the chances of seeing a satellite reentry are therefore larger than usual for anyone between 53 N and 53 S. So keep an eye on the sky!

screenshot of Feb 8 announcement on the SpaceX website

Though it remains to be seen which of the 40 satellites it actually was, the Feb 7, 6:40 UT, Puerto Rico sighting can be possitively linked to this deluge of decaying Starlink satellites. 

One clue is that the orbital plane of this launch was over Puerto Rico near the time of the event, and the direction of movement (SW-NE) matches it.


To get even more certainty, I did some astrometry on the footage and fitted a rough circular orbit to the measured positions.The rough orbital fit I get - I measured three fragments-  yield orbital inclinations in the range of 54-56 degrees: Starlink satellites are in 53.2 degree inclined orbits, so this is close enough (given the error margin) to conclude that the reentering object fits with the Starlink orbital plane. The RAAN values also match to a degree or so. So there is very little doubt that this was a Starlink satellite reentering.

One reason why I checked this, is that someone suggested another candidate, a Falcon 9 rocket stage from a 2017 launch (2017-014B), which was also expected to reenter around this date (in fact it had already reentered a day earlier) and had its orbital plane passing over Puerto Rico at the time of the event. This rocket stage however had an orbital inclination of 22 degrees, which is clearly much lower than what I get for the reentering object in the footage.

Starlink satellites are not very big and do not have big rocket engines, so there is very little chance that anything remains and reaches Earth surface from these reentries: it will all burn up in the atmosphere. 

Note: I thank Eddie Irizarry for alerting me to the Puerto Rico event


UPDATE 17:30 UT (9 Feb 2022):
For some 21 of the 45 49 Starlink satellites in question, orbital elements have now been released by CSpOC. A quick assessment with SatEvo suggests reentries happening over the coming week, up to mid-February.

Wednesday, 2 February 2022

The upcoming classified NROL-87 launch

click map to enlarge


If weather cooperates, SpaceX will launch a classified payload for the National Reconnaissance Office (NRO) on 2 February 2022 at 20:18 UT [the launch eventually was at 21:27 UT]. This launch, from Vandenberg SLC-4 in California, is designated NROL-87.

Both (limited) specifications in a published contract for this launch (which states the intended orbital inclination and semi-major axis as respectively 97.4 degrees and 6890.7 km), as well as the position and orientation of hazard zones published in Navigational Warning NAVAREA XII 45/22 point to a launch into a 97.4 degree inclined, Sun-Synchronous Low Earth Orbit at about 512 km orbital altitude.

Analysts suspect the classified payload is one of a new generation of electro-optical IMINT satellites (either the first, or possibly the second, after USA 290/NROL-71, but in the latter case in a clearly different orbit) that is a follow-up to the KH-11 program. The sun-synchronous character of the intended orbit supports interpretation as an IMINT mission.

The image in top of this post gives the launch trajectory. The hazard areas I plotted in the map are from Navigational Warning NAVAREA XII 45/22 and they match a launch into an orbital plane with the quoted orbital inclination of 97.4 degrees:

280731Z JAN 22
NAVAREA XII 45/22(17,18,19).
   A. 1907Z TO 2138Z DAILY 02 AND 03 FEB
      34-42N 120-41W, 34-41N 120-32W,
      34-31N 120-26W, 34-18N 120-30W,
      33-40N 120-53W, 32-10N 121-24W,
      31-25N 121-27W, 31-07N 121-40W,
      31-09N 121-55W, 31-35N 121-52W,
      32-17N 121-27W, 34-29N 120-46W.
   B. 2110Z TO 2249Z DAILY 02 AND 03 FEB
      54-00N 144-30W, 50-45N 134-30W,
      29-15N 140-00W, 32-30N 150-30W.
2. CANCEL THIS MSG 032349Z FEB 22.

The Falcon 9 upper stage from the launch makes a controlled reentry at the end of the first revolution, in the Northeast Pacific roughly between Alaska and Hawaii (the red box marked "B" in the map above). 

If launch is indeed near 20:18 UT (the launch window of the Navigational Warning runs from 19:07 to 21:38 UT), then the orbital plane launched into results in passes near noon and midnight local time and (if the semi-major axis is correct) a ~5-6 day repeating ground track. A pre-launch estimated elset is here.

The Launch Patch for NROL-87 shows an Ibex keeping a watchfull eye over its territory:

image: NRO

The North Korean Hwasong-12 test of 29 January 2022

click to enlarge

On 29 January 2022 at 22:52 UT (30 January 2022, 7:52 local time in North Korea), North Korea test-fired a Hwasong-12 IRBM. The missile impact point was in the Sea of Japan. According to western sources, it had as flight time of ~30 minutes with a range of ~800 km and an apogee of ~2000 km (the yellow trajectory in the reconstruction above). In other words, a highly lofted trajectory, such as we have seen earlier during various 2017 North Korean missile tests. 

Such a lofted trajectory can be chosen for two reasons: to avoid overflying other countries (Japan) and/or to be able to monitor most of the flight from North Korea itself.

Going from the reporteded apogee altitude and range (~2000 km and ~800 km), I find that this same missile would have an implicated maximum range of ~4300 km (white line in reconstruction above, and red circle) when launched on a more normal, more depressed ballistic trajectory. 

This fits with results for earlier Hwasong-12 lofted test flights, such as the 13 May 2017 test, and is slightly more than the more depressed Hwasong-12 test firings over Japan of 29 August 2017 (which as I have pointed out partly failed but was intended to fly ~3300 km) and 14 september 2017 (which flew ~3700 km).


images: KCNA/Rodong Sinmun


Images of the launch published by the North Korean Government in Rodong Sinmun (above) include two images of the earth reportedly made from the missile, showing the Korean peninsula.

From the two published launch pictures, the launch location of the missile was geolocated by Joseph Dempsey to a spot near Mupyong-ri at 40.6112 N, 126.4257 E. In the image below I match particular terrain details in the drone launch image released by North Korea to a Google Earth image of that particular spot. Which is a familiar spot by the way: it is the same courtyard where on 28 July 2017 the first successful launch of a Hwasong-14 ICBM was carried out (at that time the courtyard was still grass covered: in the meantime it has been paved). On recent Google Earth imagery, what I think could very well be a monument built to commemorate the 2017 launch is visible near the southern courtyard perimeter (we know the North Korean's built commemorative monuments on other test launch sites). I have indicated it in the image below.


click to enlarge

The text of the post-launch North-Korean Government announcement in Rodong Sinmun of 31 January 2022 is interesting. It claims that the  "test-fire was aimed to selectively evaluate the missile being produced and deployed and to verify the overall accuracy of the weapon system". 

As Ankit Panda has pointed out, this probably indicates that this was not a test of a new improved Hwasong-12 variant: but rather a test launch to demonstrate the readiness of a deployed system of production grade missiles (similar to frequent test launches of Minuteman ICBM's and Trident-II SLBM's by the USA). We might therefore see more of such periodical launches in the future.

This was the 7th launch of a Hwasong-12, and the first launch of this type since 15 September 2017.

Friday, 3 December 2021

Some first analytical results on the debris from the Russian ASAT test of 15 November 2021


click image to enlarge

In my previous post I discussed the November 15 Anti-Satellite (ASAT) test on the defunct Kosmos 1408 satellite by Russia. On December 1, CSpOC released the first sets of orbital elements for debris fragments created by the test. As of yesterday 2 December, when I made the preliminary analysis presented below, orbits for 207 fragments were published (many more will probably be added in the coming days and weeks). 

They allowed to construct the Gabbard-diagram below, which for each debris fragment plots the apogee altitude (blue) and the perigee altitude (red) against orbital period. They also allowed a preliminary analysis on the delta V's (ejection velocities) imparted on the debris fragments by the intercept.


click diagram to enlarge


Let's first discuss the Gabbard diagram. Gabbard diagrams show you at a glance what the altitude distribution of the created debris fragments is. As can be seen, most of the debris has a perigee (lowest point in the elliptical orbit) near the original orbital altitude of the Kosmos 1408 satellite (490 x 465 km: the intercept happened at an altitude of ~480 km): but a part of the generated debris evidently has been expelled into orbits with perigees (well) below that altitude too. The apogee altitudes (highest point in the elliptical orbit) are mostly scattered to (much) higher altitudes. In all, debris moves in orbits that can bring some debris as low as 185 km and as high as 1290 km. As can be seen, the debris stream extends downwards into the orbital altitudes of the ISS and the Chinese Space Station. About 35% (one third) of the currently catalogued debris has a perigee altitude at or below the orbit of the ISS: about 18% at or below the orbit of the Chinese Space Station. Upwards, the distribution extends well into the altitudes were many satellites in the lower part of Low Earth Orbit are operating, with the bulk of the debris reaching apogee altitudes of 500 to 700 km.

The plots below show the altitude distributions for apogee and perigee of fragments as a bar diagram:

Distribution of perigee altitudes. Click diagram to enlarge

Distribution of apogee altitudes. Click diagram to enlarge

From the change in apogee and perigee altitudes and change in orbital inclination of the debris fragments in comparison to the original orbit of Kosmos 1408, we can calculate the ejection velocities (delta V) involved. It is interesting to do this and compare it to similar data from two other ASAT tests: the Indian ASAT test of 27 March 2019 and the destruction by an SM-3 missile of the malfunctioned US spy satellite USA 193 on 20 February 2008.

In the plot below, I have plotted the density of debris against ejection velocity (in meter/second) for the Nov 15 Russian ASAT test as a bar diagram (with bins of 5 m/s: the blue line is the kernel density):

click diagram to enlarge

In the diagram below, where I have removed the bars and only plotted the kernel density curves, a comparison is made between ejection velocities from the Russian ASAT test and the Indian and US ASAT tests of 2019 and 2008:


click diagram to enlarge

The two diagrams below do the same, in combined bar-graph form, for both the earlier ASAT tests. The first diagram compares the delta V distribution from the Russian ASAT test (blue) to that of the 2008 USA 193 destruction (red); the second diagram does the same but compared to the 2019 Indian ASAT test:

delta V of Russian ASAT fragments vs USA 193. Click diagram to enlarge

delta V of Russian ASAT fragments vs Indian ASAT. Click diagram to enlarge

The diagrams clearly show two things: the distribution of ejection velocities from the Russian ASAT test peaks at lower delta V's than that of the debris from the USA and Indian ASAT tests. In addition, the distribution is more restricted, lacking the tail of higher ejection velocities above 200 meter/s present in the distribution from the other two ASAT tests (we should note here however that this is all still based on early data, and addition of new data over the coming weeks might alter this picture somewhat).

This tallies with what we know about the Russian ASAT test: rather than a head-on encounter with the interceptor moving opposite to the movement of the target, such as in the 2008 American and 2019 Indian ASAT tests, the Russian ASAT intercept was performed by launching the interceptor in the same direction of movement as the target (as shown by NOTAM's related to the launch of the interceptor, see map below), letting the target "rear-end" the interceptor. This results in lower kinetic energies involved, explaining the more compact fragment ejection velocity distribution emphasizing lower ejection velocities. In addition, the possible use of an explosive warhead on the interceptor rather than a kinetic kill vehicle might have some influence.

click map to enlarge

So the Russian test seems to have been designed to limit the extend of ejection velocities and from that limit the extend of the orbital altitude range of the resulting fragments. That is in itself commendable, but it doesn't make this test less reckless or irresponsible

The Gabbard diagram near the top of this post, and the bar graphs below it, show that debris was nevertheless ejected into a wide range of orbital altitudes, from as low as 200 km to as high as 1200 km, with a peak concentration between 400 and 700 km altitude. The orbital altitude range of the debris includes the orbital altitudes of crewed space stations (ISS and the Chinese Space Station), thereby potentially endangering the crews of these Space Stations, as well as the busiest operational part of Low Earth Orbit. The diagram below gives the perigee altitude distribution of objects (including "space debris") in Low Earth Orbit, for comparison (note, as an aside, the prominent peak caused by the Starlink constellation at 550 km).

click diagram to enlarge

Tuesday, 16 November 2021

The Russian Federation conducted a destructive ASAT test on Kosmos 1408 on November 15 [updated]

click map to enlarge

In the early morning of November 15, astronauts and kosmonauts onboard the ISS were instructed to put on their spacesuits and retreat to their Soyuz and Crew Dragon capsules. The reason was a close approach with a space debris swarm.

In the hours following this, news broke that Russia had conducted a 'destructive Direct Ascent ASAT missile test' that morning, and it quickly transpired that both events were related. US Space Command and later, in a press conference, the spokesman of the US State Department announced that a Russian direct ascend ASAT test had destroyed an old defunct Russian Tselina satellite, Kosmos 1408 (1982-092A) launched in 1982. The ASAT test created over 1500 trackable orbital pieces of debris and probably hundreds of thousands of smaller particles, according to US Space Command. 

Some of these orbital debris pieces seem to have threathened the International Space Station within hours of the event (a situation somewhat reminiscent of the plot of the movie 'Gravity'), almost immediately showing how reckless and dangerous such a destructive test is.

A set of two Navigational Warnings (HYDROARC 314/2021 and HYDROARC 316/2021) issued a few days before the test, point to a missile launch from Plesetsk towards the pole. The two Navigational Warnings in question:

 HYDROARC 314/2021 (38)

 DNC 27.
    150200Z TO 150500Z NOV, ALTERNATE
    170200Z TO 170500Z NOV IN AREA BOUND BY
    83-00N 099-00E, 83-00N 137-00E,
    77-10N 137-00E, 76-00N 134-30E,
    77-20N 121-40E, 77-50N 109-40E,
    78-20N 106-50E, 78-40N 106-50E,
    80-30N 099-00E.
 2. CANCEL THIS MSG 170600Z NOV 21.

 091740Z NOV 2021 NAVAREA XX 184/21 091732Z NOV 21.

 HYDROARC 316/2021 (42)

 DNC 22.
    0200Z TO 0500Z DAILY 15 AND 17 NOV
    68-33.1N 047-36.2E, 68-20.3N 048-45.3E,
    67-01.4N 046-43.0E, 67-13.0N 045-51.0E.
    67-53.1N 046-50.3E.
 2. CANCEL THIS MSG 170600Z NOV 21.

 101800Z NOV 2021 NAVAREA XX 187/21 101728Z NOV 21.

Kosmos 1408 made two passes over the relevant polar region during the time window of the two Navigational Warnings, one near 2:52 UT and one near 4:27 UT (Nov 15), with the 2:52 UT pass particularly lining up well with the apparent missile trajectory (making it likely that the ASAT test was conducted around that time). 

This can be seen in the map below, which shows the two areas from the Navigational Warnings, as well as Plesetsk, and the trajectory of Kosmos 1408 during the time window of the warnings (2:00-5:00 UT). The relative geometry of the apparent missile trajectory and the satellite trajectory shows that this test had the kill vehicle approach the target from behind, rather than head-on. 

[edit 16 Nov 2021 9:14 UT: as Richard Cole rightly remarked in the comments, it is unlikely that the interceptor reached the same orbital speed as the satellite, so rather than the interceptor coming 'from behind', it was probably more: launch the interceptor in the same direction of movement as the satellite, while making sure it ends up slightly in front of the target, and then let the target rear-end the interceptor]

click map to enlarge

Jonathan McDowell has shown that the time window during which the ISS astronauts were instructed to retreat to their spacecraft for safety, coincides with the International Space Station passing through the orbital plane of Kosmos 1408, so the two events seem definitely linked.

Kosmos 1408 moved in a 82.56 degree inclined, 490 x 465 km orbit. This is somewhat (but not much) higher in orbital altitude than the 424 x 418 km orbit of the ISS, but as the destruction scattered the debris in orbital altitude, the event evidently generated debris at ISS altitudes too. 

As Kosmos 1408 was in a polar orbit, the ISS passes through the orbital plane of the former satellite twice during each 1.5 hour revolution around the earth, i.e. some 31 times each day. As the orbits of debris pieces decay over time, more fragments than currently already are at that altitude will reach the ISS orbital altitude. This process will probably continue  for a long time to come (months to years). 

Over time, the debris will spread and the orbital planes of the debris pieces will spread: as the Kosmos 1408 orbit was polar, this means that eventually the debris layer will envelop virtually the whole globe, threathening all inclinations in Low Earth Orbit. It is clear that there is a serious increase of risk here.

In my opinion, this destructive, debris-generating Russian ASAT test therefore was extremely reckless and highly irresponsible. It endangers other satellites (e.g. Starlink satellites in their initial insertion orbit, and many cubesats, as well as several 'normal' satellites in the lower part of Low Earth Orbit. And at almost each launch, the launch vehicle will have to move through the debris layer), and it endangers the inhabitants (including Russian kosmonauts!) of the International Space Station. Following the Chinese ASAT test from 2007 (of which debris is still orbiting) and the Indian ASAT test of 2019, this new Russian test again has significantly added to space debris in Low Earth Orbit, peppering it with large numbers of debris pieces.

It once again underlines the urgent need for a treaty that prohibits these kind of utterly reckless destructive on-orbit anti-satellite tests.

Recently, a group of SSA and Space Policy professionals have started a movement to call for a test ban on ASAT activities. Perhaps, the Russian test was an opportunistic act to get in a quick live shot before the movement to end these kind of activities in space gains any real traction.

It took some two years for debris from the 2019 Indian ASAT test to clear (one tracked debris fragment from that test is currently still in orbit), and that test was perfomed at a clearly lower altitude (285 km) than the current Russian test (~480 km). The initial spread in orbital altitude and eccentricity of the debris fragment created might be somewhat different due to different intercept configurations, but we can expect debris to be around for quite a while.

[This is a developing story. as more information hopefully comes availabe in the coming days or weeks, I might update this blogpost accordingly]