Tuesday 22 October 2019

A reanalysis of the Trident SLBM test of 10 September 2013 and other tests

9 May 2019 Trident-II D5 test launch from USS Rhode Island in front of Florida
Photo: John Kowalski/US Navy

NOTE: This post reanalyses a case from September 2013 that turned out to be a Trident SLBM test launch. New information on the launch trajectory allows to glean information on the missile's apogee. The 10 September 2013 test launch trajectory is compared to those of several other Atlantic Trident test launches in subsequent years

Elements of this re-analysis were already published in May of this year in two Twitter threads here and here. As Twitter is highly ephemeral in nature, this blog post serves to preserve and consolidate the two analysis.


On 9 May 2019, I noted a Maritime Broadcast Warning issued for the period of May 9 to 12, that clearly defined the trajectory of  a Trident-II SLBM test in the Atlantic (this was was later confirmed to be a Trident test launch from the submarine USS Rhode Island):

NAVAREA IV 394/2019 

(Cancelled by NAVAREA IV 403/2019)

   091340Z TO 120026Z MAY IN AREAS BOUND BY:
   A. 28-53N 080-01W, 29-00N 079-35W, 28-55N 078-58W,
      28-38N 079-00W, 28-40N 079-37W, 28-50N 080-01W.
   B. 28-34N 076-26W, 28-24N 075-24W, 28-10N 075-27W,
      28-21N 076-29W.
   C. 27-45N 070-22W, 27-14N 068-45W, 26-48N 068-56W,
      27-18N 070-32W.
   D. 17-46N 045-38W, 16-22N 042-18W, 15-44N 042-36W,
      17-09N 045-55W.
   E. 15-47S 004-32E, 17-17S 007-04E, 17-10S 007-08E,
      17-29S 007-49E, 17-20S 007-52E, 17-19S 008-07E,
      17-28S 008-12E, 17-41S 008-04E, 17-45S 008-14E,
      18-27S 007-50E, 17-51S 006-44E, 17-43S 006-50E,
      16-11S 004-16E.
2. CANCEL THIS MSG 120126Z MAY 19.

071718Z MAY 2019 EASTERN RANGE 071600Z MAY 19.

The five hazard areas defined in the Broadcast Warning correspond to: the launch area in front of the coast of Florida; the splash-down zones of the three booster stages;  and the MIRV target area in front of the Namibian coast. This is what it looks like when the coordinates are mapped - the dashed line in the map below is a modelled simple ballistic trajectory between the lauch area and target area:

click map to enlarge

The case brought me back six years, to September 2013, when I was asked to look at photographs made by German astrophotographer Jan Hattenbach that showed something mysterious. I suggested it was a missile test, a suggestion which was later confirmed.

In this blog post, I revisit the 2013 analysis in the light of new information about this test, and compare it to other tests for which I could find trajectory information.

In the evening of 10 September 2013, Jan Hattenbach was making a time-lapse of the night sky near the GranTeCa dome at the Roque de los Muchachos observatory on La Palma in the Canary Islands, at 2300 meter altitude.

Suddenly, a strange fuzzy objects producing cloudy "puffs" moved through the sky. I wrote about it in two blog posts in 2013 (here, and follow-up here), identifying the phenomena as a Trident-II SLBM test launch conducted from a US Navy Ohio-class submarine.

This is Hattenbach's time lapse of the phenomena: the fuzzy cloud moving from bottom center to upper left is the missile (the other moving object briefly visible above the dome is a Russian satellite, Kosmos 1410). The distinct "puffs" are likely the missile's Post-Boost Control System (PBCS) reorienting while deploying RV's during the post-boost phase:

Here is a stack of the frames from the time-lapse, and a detail of one of the frames:

click to enlarge

click to enlarge

At that time, Ted Molczan had managed to dig up a Broadcast Warning that appeared to be for the MIRV target area:

( 090508Z SEP 2013 )
HYDROLANT 2203/2013 (57) 
(Cancelled by HYDROLANT 2203/2013)

   09-18S 000-26W, 09-50S 000-32E,
   12-03S 002-39E, 13-40S 004-09E,
   14-09S 003-49E, 13-06S 001-56E,
   11-05S 000-58W, 10-55S 001-05W,
   09-56S 000-50W.
2. CANCEL THIS MSG 140230Z SEP 13.

The case of May this year made me realize there should be Broadcast Warnings for the launch area and stage splashdown zones as well. Searching the database for such Navigational Warnings, I indeed managed to find them, as a separate Broadcast Warning:

( 082155Z SEP 2013 )
NAVAREA IV 546/2013 (24,25,26) 
(Cancelled by NAVAREA IV 546/2013)

   A. 28-57N 076-17W, 28-56N 075-54W,
      28-44N 075-11W, 28-29N 075-13W,
      28-43N 076-17W.
   B. 27-53N 073-02W, 28-14N 072-56W,
      27-58N 071-52W, 27-46N 071-08W,
      27-38N 071-11W, 27-39N 071-43W,
      27-39N 071-48W, 27-41N 072-04W.
   C. 26-42N 066-58W, 26-16N 065-36W,
      25-37N 063-38W, 25-18N 063-35W,
      25-06N 063-42W, 25-02N 063-52W,
      25-39N 065-51W, 26-07N 067-12W.
   D. 15-59N 043-47W, 16-51N 043-14W,
      15-54N 040-54W, 14-19N 038-09W,
      13-48N 038-28W, 13-30N 039-26W.
2. CANCEL THIS MSG 140230Z SEP 13.

When the coordinates of these two Broadcast Warnings are mapped, they define a clear trajectory for this test (map below). It is somewhat different from the hypothetical trajectory we reconstructed in 2013 (the launch site is at a different location, much closer to Florida) and it is very similar to that of the recent May 2019 test. The dashed line is, again, a modelled simple Ballistic trajectory between the launch area and MIRV impact area, this time fitting the hazard areas extremely well:

click map to enlarge

The trajectory depicted is for an apogee height of 1800 km. This altitude was found by modelling ballistic trajectories for various apogee altitudes, and next looking which one of them matches the actual sky positions seen in Hattenbach's photographs from La Palma best.

In order to do so, I astrometrically measured Jan Hattenbach's images in AstroRecord, measuring RA and declination of the missile in each image using the stars on the images as a reference. The starmap below shows these measured sky positions, as red crosses.

When compared to various modelled apogee altitudes (black lines in the starmap), the measured positions best match an apogee altitude of ~1800 km:

click starmap to enlarge

So, we have learned something new about the Trident-II D5 apogee from Hattenbach's La Palma observations. At 1800 km the apogee is a bit higher than initially expected (ICBM/SLBM apogees normally are in the 1200-1400 km range).

This is how it approximately looks like in 3D (green lines depict the approximate trajectories of the missile stages). The ground range of this test was about 9800 km:

click to enlarge

Out of curiosity, and now knowing what to look for in terms of locations, I next searched the Broadcast Warning database for more Broadcast Warnings connected to potential Trident-II tests. I found six of them between 2013 and 2019, including the 10 September 2013 and 9 May 2019 test launches. It concerns additional test launches in June 2014, March 2016, June 2016, and June 2018. Putting them on a map reveals some interesting patterns, similarities and dissimilarities:

click map to enlarge

The set of Broadcast warnings points to at least two different launch areas, and three different MIRV target areas.

The two launch areas are in front of the Florida coast, out of Port Canaveral. One (labelled A in the map) is located some 60 km out of the coast, the other (labelled B in the map) is further away, some 400 km out of the coast.

I suspect that the area closest to Florida is used for test launches special enough to gather an audience of high ranking military officials. The recent test of 9 May 2019 belongs into this category, as well as a test in June 2014, and also the infamous British Royal Navy test of June 2016 (I will tell you why this test has become infamous a bit later in this blog post).

As to why area A is tapered and area B isn't, I am not sure, except that the launch location for these tests could perhaps be more defined, restrained by the audience that needs a good, predefined and safe spot to view it.

Click map to enlarge

Not only are there two different launch locations near Florida, but likewise there are at least three different MIRV target areas near Africa.

Four tests, including the 10 September 2013 test imaged by Hattenbach, target the same general area, some 1000 km out of the coast of Angola (indicated as 'impact area 1' in the map below). Two of the tests however target a slightly different location.

click map to enlarge

One of these two deviating tests is the earlier mentioned infamous Trident-II test by the British Royal Navy from June 2016.

This test has become notorious because the Trident missile, fired from the submarine HMS Vengeance, never made it to the target area. Instead it took a wrong course after launch, towards Florida (!)  and had to be destroyed. That test had a planned target area (dark green in the map above) somewat shortrange from the other tests, closer to Ascension island. This is the shortest ground range test of all the tests discussed here, approximately 8900 km, some 1000 km short of most other tests. Incidently, the choice of launch area indicates this failed test had a launch audience, so I reckon some top brass was not amused that day.

The other is the recent 9 May 2019 test. This US Navy test had a target area (red in the map above) some 400 km out of the African coast, further downrange from previous tests. This is the longest range test of all the tests discussed here, with a ground range of approximately 10 700 km, about 700 km longer than the other tests. From the choice of launch area, this test too might have had a launch audience.

The other tests had a range of 9600 to 9900 km. The different ranges could point to different payload masses (e.g. number or type of RV's), different missile configurations, or different test constraints.

There have certainly been many more Trident-II tests than the six I could identify in Broadcast Warnings (e.g. see the list here). Why these didn't have Broadcast Warnings issued, or why I was not able to identify those if they were issued, I do not know.

The Trident-II is a 3-staged Submarine-Launched Ballistic Missile with nuclear warheads. The missile is an important part of US and British nuclear deterrance strategies. The missiles are caried by both US and British Ballistic Missile submarines.

click to enlarge

Edit 23 Oct 2019:
Considering the Trident-II D5 range, the US Navy clearly needs to update it's own 'fact file' here (which at the time of writing lists a maximum range of 7360 km, well short of the distances found in this analysis)

Saturday 19 October 2019

The structure of space: orbital families

click diagram to enlarge

Asteroid observers are well acquainted with the kind of diagram above: a plot of the semi-major axis of the orbit against orbital inclination. Doing this for asteroids allows to discern resonances, and clusters visible in such a diagram point to related objects with a shared origin (asteroid 'families').

The diagram above is however not showing asteroids in heliocentric orbits, but is a similar diagram showing orbits for all 18439 well-tracked artificial objects (satellites, rocket stages and debris) in orbit around our Earth. A number of clusters can be seen: the distribution of the objects in a-i space (*) is not random but structured.

The structure corresponds to satellites with a specific purpose (and the related rocket stages and debris), or from a specific family. Some functions of satellites demand a specific type of orbit distinguishable in a-i space.

Well recognizable clusters for example in the plot above, are Geosynchronous satellites; and satellites in HEO ('Molniya') orbit. These are often communication or SIGINT satellites. NAVSTAR navigation satellites (GPS) form a recognizable cluster too.

Two loose clusters of objects can be seen that correspond to Geostationary Transfer Orbits (GTO). These are the rocket stages left from launches into Geostationary orbit. They move in eccentric orbits with low inclination. Two groups can be discerned: those launched from Kourou in French Guyana by ESA, and those launched from Cape Canaveral by NASA and NRO. The fact that these two groups group and distinguish in inclination, is because the inclination of GTO launches correlates to the latitude of the launch site.

Some clusters are debris clusters which are the result of the breakup of objects (usually exploding rocket stages) in space: two of these are indicated in the plot above.

Interesting is also the cluster that represents Earth Observation satellites in sun-synchronous Polar orbit. Let us look at this part of the plot in more detail:

click diagram to enlarge

Sun-synchronous objects are objects in orbits designed to have a rate of RAAN (node) precession that matches the precession of the sun in Right Ascension. This is beneficial to optical remote sensing observations of the earth, as it means the orbital plane moves along with the shift in Right Ascension of the sun, thus ensuring that images are made around the same solar time each day, which aids shadow analysis.

The objects in this cluster display a clear obliquely slanted trend in a-i space. This is because the sunsynchronous character of an orbit is a function of semi-major axis, eccentricity and orbital inclination. Hence, a specific orbital inclination is necessary for each orbital altitude, causing the slant in the distribution in the plot above.

[EDIT 19 oct 2019, 21:55 UT]

In the diagram below, the black line is the theoretical trend in a-i space for a circular sun-synchronous orbit. For more elliptical orbits, the slant of the line is slightly different:

click diagram to enlarge

I am not entirely sure what is behind the noticable gap visible in the distribution around inclination 101 degrees. The upper sub-cluster around 102 degrees inclination contains a number of meteorological satellites, plus debris from associated, broken up rocket stages, so it might be a sub-cluster representing a specific family of satellites

A couple of other object 'families' can be seen in this detail diagram as well, as distinct clusters. There is another breakup event visible (Kosmos 1275, a Soviet navigation satellite that disintegrated in orbit some 50 days after launch), as well as two payload families, including the Iridium satellites. The Westford Needles are tiny metal rods that are the result of a weird,  ill-conceived and eventually abandoned communication experiment during 1961 and 1963 (read more here).

* note: a-i means: semi major axis (a) versus orbital inclination (i)