Tuesday 19 December 2017

[UPDATED] Where to hide your nuclear missile submarine? (but be quick)

(Updated 20 Dec 2017 23:25 UT with a new plot that includes DSP)

Say, you are the leader of a nefarious country that is in posession of submarines equiped with long range nuclear missiles. You want to launch a stealth missile attack codenamed "Operation Orange Squeeze" on a northern hemisphere Super Power.

Where would you direct your submarine, and where would you best fire you missiles, from the perspective of an as-late-as-possible space-based detection of your missile launches?

The answer came to me today when, after a question by someone (in the context of a war crime investigation), I looked into the current global coverage of the Space Based Infra Red System (SBIRS), the US system of Early Warning satellites that looks for missile launches:

click map to enlarge

The red areas in the map above have an almost continuous coverage by SBIRS satellites (and often by multiple SBIRS satellites at the same time). The dark blue and black areas in the map by contrast have only a few minutes of SBIRS coverage each day, or even none at all.

As you can see, there is a clear gap in coverage in the southeastern Pacific, with lowest coverage in the area near the Galapagos islands. That is where I would park my nuclear missile submarine.

You might have to be quick to pull off your nefarious plan though. A new SBIRS satellite, the fourth satellite in the geostationary component, will launch in January. It wouldn't surprise me if it stops the gap, once operational.

Of course, this map is in fact somewhat deceptive anyway. It only shows the coverage by SBIRS. But there is also the legacy early warning satellite system called DSP (Defense Support System), which still has active satellites, and which is not taken into account here [UPDATE: but see the plot at the end of this post!]. It is less sensitive than SBIRS, but likely will detect your ICBM SLBM launch.

Back to SBIRS. SBIRS is made up of two components, each currently consisting of three satellites (so six in total): three geosynchronous SBIRS-GEO satellites at geostationary altitude, and three SBIRS-HEO satellites (TRUMPET-FO SIGINT satellites with a piggy-back SBIRS package) in 64-degree inclined Highly Elliptical Orbits with two revolutions a day.

click map to enlarge

The map above shows the coverage of the three geosynchronous SBIRS satellites (a fourth will be launched in January). Eurasia, Africa and the western Pacific Ocean has a continuous coverage by these satellites, with central Asia, Pakistan and India (the latter two known nuclear powers) particularly well covered.

The SBIRS-HEO coverage is more variable and depends on the date and time of day, but the system is designed such that at least one of the HEO satellites will have much of the Northern hemisphere in view at any time. Here are a few examples, for various times of the day: note how coverage of the Northern hemisphere is near-continuous (the HEO component also particularly covers the Arctic region well, which is at the edge of the GEO component's coverage).

click maps to enlarge
A SBIRS satellite typically has two modes: there is the scanning mode, which scans the whole visible hemisphere of the earth (as seen from the satellite) for infra-red heat signatures in less than 10 seconds. And there is the staring mode, a more sensitive sensor which can be used to observe a specific region or just detected infra-red event.

In the case of a missile launch, the sensors pick up the heat signal of the missile engine. Because of the large degree of worldwide coverage which the system now provides, an undetected stealth launch of a nuclear missile has become almost impossible.

SBIRS is probably an important source of  Early Warning capacity and information on the recent North Korean missile tests.

UPDATE 20 Dec 2017  23:25 UT:

I now also included the four DSP satellites that are still operational according to the database of the Union of Concerned Scientists. That leads to the following map:

click map to enlarge
As you can see, the gap has become smaller, but a gap is still there. Red October might be lurking in front of the South American west coast.


Scott Tilley said...

Marco, DSP F20 is the only DSP mission still in a synchronous orbit visible from western North America. It does provide some coverage over your SBIRS gap but was left alone after DSP F16 retired last year from its perch over the central CONUS.

Scott Tilley

SatTrackCam Leiden said...

Hi Scott,
I now have updated the post to include the operational DSP.

Scott Tilley said...

Nice, best we not antagonize the Peruvian or Chilean people until the gap gets closed. DSP's appear to indicate operational status by remaining in a GEO synchronous orbit with a stable s-band TTC beacon. After decommissioning the TT&C either goes off or becomes unstable as the mission drifts in its disposal orbit. X-band activity from DSP is something also noted that would surely indicate operational status if someone suitability equipped was in range to confirm.