Ballistic Missile Defense: Estimating the Range of an Aegis Radar against a Missile Warhead Target (October 23, 2012)

Estimating the Range of an Aegis Radar against a Missile Warhead Target

By George Lewis and Theodore Postol

In our post of September 21 (, we estimated the range of an AN/TPY-2 X-band radar against a warhead target.  For a target radar cross-section of 0.01 m2 and with a radar dwell time of 0.1 seconds, we obtained a detection range (assuming S/N = 20) of 870 km and a discrimination range (assuming S/N =100) of 580 km.  In this post, we make similar estimates for the Aegis SPY-1 radar, and get significantly shorter ranges of 550 and 370 km, respectively.  These numbers seem likely to substantially overestimate an Aegis radar’s actual operation range.


Ballistic Missile Defense: A Significant Advance in Missile Defense Criticism Evasion Technology (October 18, 2012)

In my post of April 19: What does “Successful Intercept” Mean: Maybe Not What You Think, I pointed out that the statement to the Strategic Forces Subcommittee of the House Armed Services Committee on March 6, 2012 by the Pentagon’s Director of Operational Test and Evaluation (DOT&E) J. Michael Gilmore that the interceptor in the September 2006 FTG-02 test of the Ground-Based Midcourse did not “kill” its target seemed inconsistent with the Missile Defense Agency (MDA)’s claim that the test was a “successful intercept.”  However, at the time Dr. Gilmore’s statement did not make clear precisely what had happened. 

FTG-02: A “glancing blow.” (screen capture from MDA video)

The official transcript of the hearing, with follow-up questions and answers, is now available, and this sheds some new light on the issue.

In particular, in response to a written question from Rep. Loretta  Sanchez, Dr. Gilmore explains that in FTG-02, the kill vehicle struck a “glancing blow” to the target re-entry vehicle and that subsequent analysis showed would this would not have destroyed the re-entry vehicle. 

Here is the question and answer:

Ms. SANCHEZ.  For GMD testing, is a hit considered a kill?  Does this introduce any risk in reliability assumptions for the GBIs? 

Dr. GILMORE. A hit on the threat re-entry vehicle (RV) by the exo-atmospheric kill vehicle (EKV) is not automatically considered a kill.  Ground-testing (using rocket-propelled sleds) as well as modeling and simulation demonstrate the EKV can strike the RV in a location that does not result in a kill.  This was the case in Flight Test Ground-Based Interceptor (GBI)-02 (FTG-02).  Although the flight test objectives excluded actually killing the incoming RV, the EKV achieved a “glancing blow” on the RV. Subsequent analysis indicated that the “glancing blow” would not have resulted in a kill.  I score the FTG-02 flight test a hit, but not a kill.

In principle, an intercept hit that does not result in a kill could have a number of causes some of which are not related to reliability.  The result of FTG-02, in which an RV kill was not planned (and was not achieved) is not a reliability issue.

[Note that, as discussed in the post of April 19, hitting the target, while not the primary objective of the test, was indeed a secondary objective, and MDA has stated that all of the secondary objectives of the test were achieved]

Thus it is now clear, seven years after the test, that the despite repeated claims by the MDA that the test was a “successful intercept,” that it did not actually destroy its target.  Moreover, the MDA still claims that the test resulted in a “successful intercept”.  Here is a table from a fact sheet on the MDA’s website that I downloaded today (the date on the fact sheet is July 10, 2012), showing FTG-02 as a “successful intercept.”  (The tests of operationally configured interceptors are the last six, whose names begin with “FTG”).

This appears to represent a significant advance in missile defense criticism evasion technology.  As I noted in the April 19 post, following the 1991 Gulf War, the U.S. Army specifically argued that the word “intercept” did not mean the target was destroyed.  Now it seems we have advanced to the point that even a “successful intercept” does not mean the target was destroyed.