Recently, the missile defense-related issue I have been asked about most frequently (my dentist asked me a few days ago) is the effectiveness of Israel’s Iron Dome system against short range rockets launched from the Gaza Strip into southern Israel. Many recent press reports have cited engagement success rates as high as 90%, while other reports are as low as about 75%.  My preliminary assessment based on the public literature (largely newspapers, which are often contradictory) is that that success rate is about 75%. I will update this assessment as I come across more information.

(Image source: http://www.rafael.co.il/marketing/SIP_STORAGE/FILES/6/946.pdf)

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The Wall Street Journal reported yesterday that an AN/TPY-2 X-band radar was being deployed to Qatar.[1]  This is apparently the same radar as the one that the Missile Defense Agency’s August 2011 Program Update said would be deployed to the North Arabian Gulf by the end of 2011.[2]

An AN/TPY-2 radar temporarily deployed near Juneau Alaska for a missile defense test.  The radar antenna is at far right.  The two similarly colored units adjacent to it are for cooling and  electronics.  (Photo source: Missile Defense Agency)

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The Precision Tracking Space System (PTSS) is, according to recent testimony by Missile Defense Agency (MDA) Director Lt. General Patrick O’Reilly, “the greatest potential future enhancement for both homeland and regional defense in the next ten years.”[1] PTSS is a system of satellites intended to track ballistic missiles using an infrared telescope with sufficient accuracy to be able to guide interceptors.  The PTSS program was formally initiated last year as a replacement for the Space Tracking and Surveillance System (STSS) which was the latest in a long line of proposed space-based missile tracking systems dating back to at least the late 1980s.  Two STSS “demonstration” satellites were launched in 2009, and the MDA recently noted that they had reached their 1,000th day in orbit and were still operational.[2]

PTSS Satellite (image from MDA factsheet)[3]

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More information has recently become available on the “Unexpected Energetic Event” that was apparently responsible for the failure of the first SM-3 Block IB intercept attempt (FTM-16) in September 2011.  The cause was a failure in the SM-3 interceptor’s third rocket stage motor.    Despite assurances that this component, which is common to both the IA and IB variants of the SM-3 interceptor, had performed successfully many times previously, it also apparently experienced an “anomaly” in its previous test (FTM-15, April 14, 2011, of an SM-3 IA) serious enough to temporarily halt deliveries of new interceptors.  In the most recent test, a May 2012 repeat of September’s failed intercept, the part of the third stage booster (the second pulse) that had failed previously was not used, and the interceptor hit its target.

 “Unexpected Energetic Event” during the FTM-16 intercept test, September 1, 2011.[1]

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X-Band Radar Transmit/Receive (T/R) Modules

In order to estimate the capabilities of missile defense radars such as the AN/TPY-2s used both as Forward Based X-Band (FBX) radars and THAAD theater missile defense battery radars it is necessary to assess the power output of the radars.  There do not appear to be any public official numbers for the peak or average powers of these radars.  However, one can estimate these based on the peak and average powers of transmit/receive modules making up their antennas.  This post discusses and assesses these power outputs for the TPY-2 and other X-band missile defense radars (SBX, GBR-P).  In particular, it argues that the average power outputs of the modules are 6, 10 and 16 watts for the GBR-P, SBX, and TPY-2 radars respectively

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“MISSILE  DEFENSE. IT’S NOT A GAME” proclaims the front page of the “Careers” section of the Missile Defense Agency’s website. However, right below this pronouncement, you will indeed find a box inviting you  to:  MDA GAMES: CLICK HERE TO PLAY.

MDA’s Careers page.

Following the link takes you to the MDA’s game “The Interceptor,” which offers you the opportunity to “lead one of the greatest technological acheivements of our time.” ( I assume this refers to the missile defense system, not the game).  According to the company that produced the game, it was based on the old Atari “Missile Command” arcade game  and was aimed at “college students and recent graduates.”

The Interceptor

In order to win, you must get through four levels of play without letting a total of 40 missiles get through to the city you are defending.  Fortunately, the missiles are not nuclear-armed, as the city remains standing even after being hit by multiple missiles (although there are three large buildings in the foreground that do eventually fade away after enough hits).

My favorite feature of the game is that you can advance to the second level without destroying a single attacking missile.  (In fact, you don’t even have to fire a single interceptor to advance.)   If  you  remember Patriot in the 1991 Gulf War, you will appreciate this highly realistic feature.

A missile attack underway.

In March 2011, MDA Director Lt. Gen. Patrick O’Reilly told a House of Representatives hearing that “Today, 30 operational GBIs protect the United States against a medium ICBM raid size launched from current regional threats.”[1]  Leaving aside the fact the current Ground-Based Midcourse (GMD) system interceptors (GBIs) have never actually been tested against an ICBM target, this raises the question: How many attacking missiles comprise “a medium ICBM raid size” against the GMD system?  And this question then suggests the further question: How many GBI interceptors is the MDA planning to fire at each attacking missile?

This second question is particularly interesting in light of the recent MDA and DoD claims that they intended to modify already deploy GBI interceptors to “at least double” their effectiveness [see question 2 and its answer in May 21 post “A multiple choice quiz”].  This would seem to imply that the effectiveness of the current interceptors may not be too high.

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This post is an attempt at  a graphical depiction of the GMD testing schedule.  Information on future tests is as complete as the information I can find, but is certainly incomplete.  I will update this as I get more information.  Click on the images to make them more readable.

Each row of the table shows the tests that have taken place at that time and projected future tests.  The first three rows are for mid-2009, mid-2010, and mid 2011, respectively.  The fourth row is current as of about March 2012.

KEY:

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GMD Flight Tests of Operationally-Configured Interceptors of the Ground-Based Midcourse Defense (GMD) national missile defense system.

(Update added 12/28/2012: FTG-17, listed below as taking place in FY 2016, has been delayed until 4Q FY 2019.  It will be an intercept test of a two-stage GBI against an ICBM target.  SASC 4/13/2011, p. 244).

The have been seven flight tests (five intercept attempts) of operationally configured GBI interceptors so far.  These are briefly described below, along planned future tests as best as I can figure these out. I will update as I get more information.

FT-1, December 12 2005.  First flight test of operationally-configured GBI, more than a year after the first one was deployed.  It was the first flight of the CE-I version of EKV.  It was not an intercept test; the target was computer-simulated.  Test was reportedly successful.

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