New Aegis Radar to be 100 Times More Sensitive than Current Radar (May 22, 2019)

New Aegis Radar to be 100 Times More Sensitive than Current Radar (May 22, 2019)

In my post of February 11, 2019, I discussed a number of planned new S-band radars, including the Navy’s Air and Missile Defense Radar (AMDR), which is scheduled to begin deployment on the Navy’s new Flight III Aegis destroyers in about 2023. In that discussion, I used the standard claim that the AMDR, also designated the SPY-6(V)1, would be about 15 dB = 30 times more sensitive than the current SPY-1 radar on U.S. Navy cruisers and destroyers.  I also noted, however, that there were some recent indications the AMDR might be even more sensitive, possibly by a factor of 40-70 over the SPY-1.

Now, following developmental testing of the AMDR, the Navy has validated a Raytheon Company (the manufacturer of the AMDR) assessment that the radar’s actual sensitivity is almost 100 times that of the SPY-1.[1]

The Technical Director of Raytheon’s Seapower Capability Systems, Curt von Braun, explained that “The 30 was an original number. But [during] the test period out at Pacific Missile Range Facility, we’ve been realizing additional sensitivity through our design margins that have now been tested.  So we’re more at liberty to advertise the better performance than was designed in the margins and now those are being officially realized by the radar.”[2]

According to Scott Pence, Raytheon’s Director of Naval Radar Systems, “SPY-6(V)1 is approximately 20 dB more sensitive than the SPY-1 – nearly 100 times – which translates to more than three times the original requirement” and that “SPY-6 also delivers a significant increase in range to the legacy radar.”[3]

Assuming the two radars were operated in exactly the same way (which seems unlikely), a factor of 100 in sensitivity would result in about a 3.2 times range increase against a given target.


[1] Jason Sherman, “Navy Determines SPY-6 Radar Three Times Stronger than Original Requirement,” Inside Defense SITREP, May 6, 2019.

[2] Sherman, “Navy Determines.”

[3] Sherman, “Navy Determines.”


What Did FTG-11 Actually Prove? (April 4, 2019)

On March 25, 2019 the U.S. Missile Defense Agency (MDA) conducted FTG-11, a salvo test of the US Ground-based Midcourse Defense (GMD) system in which two interceptors were fired, just under a minute apart, at a single ICBN-range missile.  

In a press release later that day, MDA described the test as follows:

“This test was the first salvo engagement of a threat-representative ICBM target by two Ground Based Interceptors (GBI), which were designated GBI-Lead, and GBI-Trail for the test. The GBI-Lead destroyed the reentry vehicle, as it was designed to do. The GBI-Trail then looked at the resulting debris and remaining objects, and, not finding any other reentry vehicles, selected the next ‘most lethal object’ it could identify, and struck that, precisely as it was designed to do.”

The MDA press release stated that “Initial indications show the test met requirements.”  It also quoted MDA Director Air Force Lt. General Samuel A. Greaves:

“The system worked exactly as it was designed to do, and the results of this test provide evidence of the practicable use of the salvo doctrine within missile defense. The Ground-based Midcourse Defense system is vitally important to the defense of our homeland, and this test demonstrates that we have a capable, credible deterrent against a very real threat.”

At yesterday’s (April 3, 2019) hearing on missile defense before the Strategic Forces Subcommittee of the Senate Armed Services Committee, General Greaves reaffirmed the success of the test.  Asked by Senator Angus King whether the test was a success, General Greaves stated that although there were nine months of data to review, the “initial look says it was a complete success.”

Senator King then asked him to “Define complete success, did the bullet hit the bullet?”

After giving some background information on testing, General Greaves stated:

“But this test was different because we launched within a very short period of time two Ground-Based Interceptors operationally released by the combatant commander using their operational processes –which is very important — and the lead interceptor intercepted the ICBM-representative threat.  But what’s most important is that it created a debris field — and this test has been 10 years or more in the making — and the importance of that was the trailing — the second — interceptor was able to discern the debris from the next most lethal object — I can talk about it in a classified forum — and also intercepted that object. What that means is [an] enemy concept of operations which seeks to confuse our missile defense system by launching junk or debris would not be successful, that’s why it was a success.” [My transcription from the video of the hearing.]

 Both the press release and the General Greaves quote immediately above make it clear that after the first intercept, there remained both debris and at least one other object.  All of these other objects must have had an appearance sufficiently different from the warhead so that the first interceptor could select the warhead.  And at least one of these other objects must have had an appearance sufficiently different from the debris so that the second interceptor could identify it.

So although when Senator Dan Sullivan asked General Greaves if the second interceptor had hit the largest debris fragment, General Greaves replied “Yes, sir,” he immediately clarified this saying that it hit “the next most lethal object” which he defined as ‘the next object that most closely resembles a threat vehicle.”

But what did FTG-15 actually prove?  Did it provide “evidence of the practicable use of the salvo doctrine” as the press release claimed?  Did it demonstrate that such the salvo doctrine would defeat enemy attempts to confuse the system as General Greaves quote suggests? I think it is clear the answer to both questions is “No.”

Strictly speaking, the test did demonstrate that the GMD system could intercept a target resembling a warhead against a field of debris, none of which resembles a warhead.  But why would any enemy try to defeat the system with such an obviously ineffective tactic (unless the warhead was disguised to look like debris)?  Moreover, the debris field that an attacker might deploy along with its warhead likely would look quite different than the debris field produced by an interceptor hitting a warhead or other object.  Finally, there was no need to launch two interceptors to conduct this demonstration.  Debris could have been launched along with the first warhead, and there would have been no need to waste a second $70 million GBI interceptor.

More importantly, the fundamental purpose of the salvo firing doctrine is to compensate for low missile defense system reliability, the interceptor reliability in particular.  For example, if the GBIs were believed to be 60% reliable (although this is slightly higher than its success rate in intercept tests – see table at end of this post — there is not enough test data to know their what actual reliability is), then salvo firing N interceptors gives a probability of killing the target of PKN = 1 – (1-0.6)N.   So for one interceptor PK1 = 0.6, for a two-interceptor salvo PK2 = 0.86, and for a three interceptor salvo PK3 = 0.936.  This is why many observers of the GMD system have speculated that the GMD firing doctrine is at least a three or four interceptor salvo against a single attacking missile.  This assumes that the failure of any one interceptor is statistically independent of the others.

A two interceptor salvo firing doctrine benefits the defense against an attacking missile when the first interceptor fails.  There is no benefit from the second interceptor if the first interceptor destroys the target, as was the case in FTG-11. 

More importantly, when an attacker takes deliberate and effective steps to defeat the defense (countermeasures), the salvo doctrine will be much less effective.  This is because if a countermeasure (and not an interceptor reliability problem) causes the first interceptor to fail, then there is a substantial probability that the countermeasure will also cause subsequent interceptors to fail.  For example, consider a case in which the warhead is disguised to look like a decoy and is accompanied by five credible light-weight decoys.  If the interceptor is unable to distinguish between the disguised warhead and the decoys, it will have to choose one of six potential targets.  Assuming  the interceptor has a same reliability as assumed above, 0.6, the chance of a successful intercept of the warhead with a single interceptor  is only PK1 = 0.6 * (1/6)  = 0.10. In a salvo of two interceptors, if the first interceptor fails to destroy the warhead, the odds for the second one are slightly better, because there is an 60% chance it will see only five targets, so the kill probability for this interceptor is P­K1­ = 0.6*0.6*(1/5) + 0.4*0.6*(1/6) = 0.112, and the overall success rate for the two intercept salvo is only PK2 = 0.201.  The salvo firing doctrine does not solve the countermeasure problem, which has long been recognized as the most important and difficult problem facing an above-the-atmosphere defense such as the GMD system

It is worth noting that FTG-11 was not MDA’s first attempt to intercept a target against a debris field.  On November 1 2015, MDA conducted test FTO-02 event 2.  In this test, a short range ballistic missile target was successfully intercepted by a THAAD interceptor, creating a debris field.  An Aegis SM-3 Block IB TU interceptor then attempted to intercept a medium-range ballistic missile against the background of this debris field.  However, the SM-3 missile failed before it could make the intercept attempt.  The target was then destroyed by a second THAAD interceptor, although it is unclear (to me) if the target was still in the vicinity of the debris field.  However, even prior to FTO-02, MDA had conducted “tests to verify interceptor performance in debris clouds” although these most likely were of systems such as the Aegis SM-3 or THAAD and involved only a single interceptor.

I think FTG-11 is better regarded as two separate intercept tests, albeit separated by less than a minute.  I have accordingly updated my Tables of Intercept Tests post of November 30, 2018, counting both tests as successes.  The GMD table from that post is below:


Estimating the Range of the Long Range Discrimination Radar (April 2, 2019)

In my post of February 11 2019, I discuss what is publicly known about the Long-Range Discrimination Radar (LRDR) now under construction in central Alaska and the closely related Homeland Defense Radars (HDRs) to be built in the Pacific. The post also discussed the new SPY-6 radar to be deployed on new construction U.S. Navy Aegis destroyers starting in about 2023 and the Lockheed Martin Solid State Radar (SSR) to be used in the planned Japanese Aegis Ashore missile defense facilities.

In this post, I attempt to make some estimates about the LRDR’s capabilities, and, by extension, those of the HDRs. This requires making some speculative, although I think reasonable, assumptions.

Only a few technical details are known about the LRDR. It has two antenna faces. Artist renderings of the LRDR suggest that the boresites of the two faces are separated by about 120°, which is consistent with the reported requirement that the LRDR must have a “wide instantaneous field of view to enable wide area defense”(see my post of January 30, 2019).  It is known that the LRDR operates in S-Band, which extends from 2 GHz to 4 GHz. S-Band was chosen over X-Band, which offers superior discrimination capabilities, largely due to cost considerations. It likely has an antenna area of about 280-300 m2 per antenna face.  For convenience, I repeat the part of my February 11 2018 post on which this conclusion about the antenna is based:

“A 2017 article stated that the LRDR will have two 3,000 square-foot antenna arrays (3,000 sq-ft = 279 m2).[1]  According to Chandra Marshall, Lockheed’s LRDR program manager, the LRDR will be about 25 times larger than a SPY-1 antenna.[2] Assuming this comparison applies to each face of the radars, since a SPY-1 antenna face has an aperture of about 12 m2, this gives an aperture of about 300 m2 for the LRDR.”

Based on this information, what can we deduce about the LRDR’s capabilities?  First, I’ll assume the smaller of the of the two antenna areas above, A = 280m2.  Assuming a square antenna, as suggested by the renderings in my February 11 post (the drawing in the January 30 post suggests a circular antenna, but this is likely an older rendering), then the antenna would be D = 16.7 m square.  Assuming that the LRDR operates at a wavelength of about λ = 8.6 cm, corresponding to a frequency of about 3.5 GHz (for comparison, the current Aegis SPY-1 radar operates at 3.1-3.5 GHz), gives an approximate beamwidth of θ ≈ λ/D = 16.7/0.086 = 0.0051 rad = 0.29°.  This gives a beamwidth of about 20 km at a range of 4,000 km.  The gain G of the antenna, assuming it is fully populated with T/R modules, is given by G = 4πA/λ2 = 480,000.

To try to get a rough estimate of the LRDR’s tracking range, I start with a basic form of the radar equation:


Rmax = maximum radar range (m),

ρ = antenna aperture efficiency,

Pav = radar average power (W),

A = antenna area (m2),

G = antenna gain,

td = beam dwell time,

σ = radar cross section of target (m2),

k = Boltzmann’s constant (1.38×10-23 J/K),

T0 = 290 K, FN = receiver noise figure,

(S/N) = signal-to noise ratio required for detection,

LS = system losses.

The problem here is that we do not know the value of many of the quantities in the radar equation, most notably Pav. One possible way around this problem is to compare the LRDR to another radar using similar technology but for which more information is available. The obvious choice here is the Aegis SPY-6.

Both the LRDR and the SPY-6 are active array radars using GaN Transmit/Receive (T/R) modules and both operate in S-Band. Both radars are state-of-the-art in their use of new GaN technology. Raytheon (the maker of the SPY-6) competed with Lockheed Martin for the LRDR, HDR-H and the Japanese Aegis Ashore SSR and won each of these contracts. This suggests that the radar technology used in the LRDR is at least comparable with that used in the SPY-6. So I will assume both radars operate at the same frequency (wavelength), will take ρ/FNLS to be the same for both radars and assume that the T/R modules in each radar have the same average power.

Since both radars operate in S-Band, it is reasonable to assume that the target radar cross section will be the same for both radars. If we then operate both radars using the same dwell time and require the same S/N for tracking, we get:

L4/R64 ≈ PLALGL/P6A6G6,

where the subscript “L” denotes the LRDR and the subscript “6” denotes the SPY-6, and the P is average power. If both radars have the same spacing between modules[3], then the average power per antenna face will be proportional to the antenna area, and since G = 4πA/λ2, we get:

L4/R64 = AL3/A63.

Using 280 m2 for the LRDR antenna area and taking the antenna area for one face of the SPY-6 to be 13.8 m2 (as discussed in my February 11 post), we get:

RL4/R64 ≈ AL3/A63 = 2803/13.83 = 20.33 = 8,370 and RL ≈ 9.6R6.

Thus if the LRDR and SPY-6 were operated in the same way and against the same target, the detection and tracking ranges for the LRDR will be about 9.6 times that of the SPY-6.  In actual practice, the LRDR will likely be operated in a way that will give an even greater range advantage.

However, this still does not give us a numerical range for the LRDR because we don’t know the range of the SPY-6.  However, we do know that the SPY-6 is expected to be at least 15dB ≈ 31.6 times more sensitive than the current Aegis SPY-1radar (see my February 11 2019 post). If the subscript “1” denotes the SPY-1, then we have:

RL4/R14 ≈ 8,370*31.6 = 264,000 and RL ≈ 22.7R1.

My post (along with Theodore Postol) of October 23, 2012 notes the claim that the SPY-1 “can track golf ball-sized targets at ranges in excess of 165 kilometers.”[4]  This claim was not made in the context of ballistic missile defense, but rather for air targets.  A golf ball-size (1.68 inches diameter) metallic sphere corresponds to radar cross section (RCS) of about 0.0025 m2 at 3.3 GHz.  Scaling this to a RCS of 0.03 m2 (for a missile target at S-Band) gives a range in excess of 310 km. Since the Aegis radar must be continually scanning the sky for incoming threats, this range is likely based on a relatively short dwell time.  Using a relatively long dwell time of 0.1 second and S/N = 20 for detection and tracking, we obtained a range of 550 km.  Using these two figures as rough lower and upper bounds on the Aegis radar range, gives upper and lower range estimates for the LRDR of 7,000 to 12,500 km.”

In a missile defense context, such large tracking ranges are not usually obtainable, because at ranges greater than about 4,000 km missile targets on minimum energy trajectories will not rise above the horizon.  However, even using the 7,000 km lower-bound range figure, the LRDR would be able to obtain a S/N on a 0.03 m2 target of nearly 200 at a range of 4,000 km.  Obviously, at shorter ranges the S/N would be much greater.

A high S/N ratio can also be essential for constructing a target object map (TOM) that allows a scene (threat cloud) viewed by a radar to be translated into the scene that would be seen by an infrared-homing kill vehicle.  For a brief discussion of this issue, see Countermeasures, pp. 77-79.[5]

As described by the 2012 National Academy of Sciences report:

“With adequate signal-to-noise ratio, a monopulse tracking radar can limit measurement error to less than 1 percent of its beamwidth. Over extended track periods, the relative positions can be refined by a further order of magnitude.  Along with measurement of relative range to a fraction of a meter, using wideband waveforms, these position data provide a three-dimensional target object map that can be converted to the angular coordinates of a homing seeker, ensuring proper registration of each object in the target cluster.”[6]

However, measuring an angular position to 1 percent of a beamwidth with a monopulse radar requires a very large S/N ratio. For a square antenna with sides D, the angular measurement error is given by:[7]

Δθ = 0.5 (S/N)-0.5 (λ/D)

Since λ/D is the approximate beamwidth, achieving an angular measurement of 1 percent of the beamwidth requires S/N ≈ 2,500.

For the lower-bound and upper-bound estimates above, a S/N of 2,500 would be achieved at ranges of about 2,100 and 3,700 km respectively.

What does the above say about the Homeland Defense Radars (HDRs)?  These are often described as scaled-down versions of the LRDR.  For example, the HDR-H, to be built in Hawaii, fills a role previously proposed for a radar that was to be called the Medium Range Discrimination Radar.  However, the projected costs of the HDRs strongly suggest that they are not much smaller than the LRDR. As discussed in my post of February 11, the HDR-H is expected to cost about $1.0 billion, about 77% of $1.3 billion cost of the LRDR.  However, the LRDR will have two radar faces, while the HDR-H will have only one.  This factor alone could account for the cost difference.

The HDR-P, on the other hand, will have two radar faces and is projected to cost the same $1.3 billion as the LRDR.  It thus seems likely to be similar in scale to the LRDR.  As discussed in my post of February 11, although the United States has not announced where the HDR+P will be built, Japanese media reports indicate that it will be built in Japan.  A two-faced HDR built in northern Japan would be able to look deep into both China and eastern Russia, and would undoubtedly encounter strong opposition from both countries.

A December 2018 Government Accountability Office report stated that: “According to DOD officials, the department may no longer need Cobra Dane to meet the ballistic missile defense mission after MDA fields a new radar in the Pacific region in fiscal year 2025,” but that it would continue to operate Cobra Dane until it was replaced with a system with greater or equal capabilities.[8] (The date for the Pacific radar has since slipped to 2026.)  The same report also stated that there would be no radar tracking coverage gap (between the TPY-2s in Japan, the Cobra Dane on Shemya Island, and the LRDR in central Alaska) once the LRDR was deployed for North Korean missiles fired towards the continental United States.  However, since the Cobra Dane is not capable of discrimination, there would be a discrimination gap for North Korean missiles launched towards the eastern United States.  In addition, once the Cobra Dane is retired (current plans call for operating it until at least 2030) there would be a tracking gap as well.

The deployment of a two-faced HDR-P in either Japan or Shemya would close both of these gaps.


[1] Marcus Weisgerber, “Pentagon Eyes Missile-Defense Sensors in Space,” Defense One, August 30, 2016.

[2] David B. Larter, “Here’s the Latest on Lockheed’s Massive Long-Range Anti-Ballistic Missile Radar,” Space News, December 9, 2019.

[3] Since the Aegis radar may only need to scan 90 degrees with each radar face, its spacing between modules could be greater than for the LRDR.  This would give a result even more favorable to the LRDR.

[4] John A. Robinson, “Force Protection from the Sea: Employing the SPY-1D Radar,” Field Artillery, March-June 2004, pp. 24-25.

[5] A.M. Sessler, J.M. Cornwall, B. Dietz, S. Fetter, S. Frankel, R. L. Garwin, K. Gottfried, L. Gronlund, G. N. Lewis, T. A. Postol, and D. C. Wright, Countermeasures: A Technical Evaluation of the Operational Effectiveness of the Planned US National Missile Defense System, Cambridge, Massachusetts: Union of Concerned Scientists /MIT Security Studies Program, 2000. Online at:

[6] U.S. National Academy of Sciences, National Research Council, Committee on Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives, Making Sense of Ballistic Missile Defense: An Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives, Washington, D.C.: The National Academies Press, September 2012, p. 137.  Online at:

[7] J.C. Toomay, Radar Principles for the Non-Specialist, 2nd ed., Mendham, New Jersey: Scitech Publishing, 1998, pp. 56-58

[8] Government Accountability Office, “Missile Defense: Air Force Report to Congress Included Information on the Capabilities, Operational Availability and Funding Plan for Cobra Dane,” GAO-19-68, December 2018, pp. 2, 11. Online at:

Upcoming MDA flight and Intercept Tests (March 27, 2019)(Revised)

Now that the Missile Defense Agency (MDA) budget materials are available, I have compiled a list of MDA’s planned flight tests and intercept tests out through 2024 (there is one test listed for 1Q FY2025).   These tests are listed in the two tables below, along with whatever other information about each test that I have been able to find (and sometimes some speculation). (Revision: at the end of the post I have repeated both tables in an easier to read (I think) format)

Two points about these tables:

(1) In the past several years, there have been very few Patriot tests listed, presumably because most of these tests are conducted by the U.S. Army, not by the MDA (except for Patriots participating in integrated intercept tests). This year, however, there are 13 Patriot flight or intercept tests listed.  All of the ones in FY 2020, and likely all of them except for the one in the integrated test FTO-03, appear to be associated with a U.S. Forces Korea (USFK) Joint Emergent Operational Need (JEON) Statement.  JEON is focused on near term improvements to U.S. missile defense in South Korea and the program was assigned to MDA, together with the U.S. Army’s Lower Tier Program Office (LTPO).  According the MDA’s FY 2020 Budget Overview: “Finally MDA continues development efforts associated with USFK JEON that provides enhanced THAAD capability against specific USFK threats, integrates THAAD’s capability to detect and track threat ballistic missiles at long ranges [for use] with the Patriot Advanced Capability – 3 Missile Segment Enhancement (PAC-3 MSE) to take advantage of its full kinematic capability, integrate MSE launchers and missiles into the THAAD weapon system, and accelerates initial capability to [use] remote launchers and increase defended area.”  With the exception of FTO-03, I have put all the Patriot tests into a separate Table 2.

(2) The budget materials show one “Israeli Cooperative Intercept Flight Test” per year from FY 2019 to FY 2024. However, each of these “tests” span an entire year, and each is apparently a series of tests rather than a single test.  The FY 2020 MDA Budget Overview says:  “In FY 2020, the MDA budget will also support several flight tests across the Israeli portfolio.”  Since I cannot (yet, at least) associate tests with particular dates and systems, I have not included these in the tables.

Table 1: Upcoming MDA Flight/Intercept Tests

Designation Date (FY) Description/Comments
FS-19 E4 3Q 2019 DT intercept test as part of NATO Formidable Shield exercise in the Atlantic. Likely SM-6 or SM-3 Block IB.
FTM-31 E1 4Q 2019 DT/OT salvo intercept of MRBM by SM-6 Dual II interceptors
FTM-31 E2 4Q 2019 Aegis DT intercept test?
FTT-23 4Q 2019 THAAD intercept test demonstrating remote launch
FTM-32 2Q 2020 DT/OT salvo intercept of MRBM by SM-6 Dual II interceptors
FTM-33 2Q 2020 DT/OT SM-6 interception of multiple SRBMs
FTM-44 2Q 2020 SM-3 Block IIA intercept test.  Likely this is the Congressionally-mandated test against an ICBM.
FTM-30 4Q 2020 DT/OT SM-3 Block IIA intercept of MRBM with countermeasures
FTO-03 4Q 2020 OT integrated intercept test for EPAA Phase3. Patriot intercept +THAAD intercept of IRBM + 2 SM-3 Block IIA intercepts of IRBMs.  One Block IIA Launched from a ship, one from the test Aegis Ashore site in Hawaii.
GM BVT-03 4Q 2020 Flight test of GBI booster with 2/3 stage selection capability. No target.
TH CTV-01 1Q 2021 DT THAAD test flight.  No target.  Involves Army LTPO.  May be part of USFK JEON?
JMTF-07 E1 2Q 2021 US/Japan DT intercept test.  Possibly SM-3 Block IIA or SM-6?
JMTF-07 E2 2Q 2021 US/Japan DT intercept test.  Possibly SM-3 Block IIA or SM-6?
FTT-21 2Q 2021 DT THAAD intercept test.
FS-21 E4 4Q 2021 DT intercept test as part of NATO Formidable Shield exercise in the Atlantic.
GM CTV-03 2Q 2022 GMD flight test . First flight test of Redesigned Kill Vehicle (RKV).  No target.
FTM-38 4Q 2022 DT/OT Aegis intercept test
FTM-37 1Q 2023 OT Aegis intercept test
FTG-17 1Q 2023 DT GMD intercept test.  First RKV intercept test
FTT-24 3Q 2023 DT THAAD intercept test
FTM-43 4Q 2023 DT/OT Aegis intercept test
FS-23 E4 4Q 2023 DT intercept test as part of NATO Formidable Shield exercise in the Atlantic.
FTG-18 1Q 2024 DT/OT GMD intercept test.  Second RKV intercept test
FTM-40 2Q 2024 DT/OT Aegis intercept test
FTG-19 1Q 2025 DT/OT GMD intercept test

DT = developmental test, OT = operational test

Table 2: Patriot Tests

Designation Date (FY) Description/Comments
FTP-21 2Q 2020 DT Patriot intercept test
FTP-27 E1 2Q 2020 DT/OT Patriot flight test, demonstrating interoperability with THAAD system.
FTP-27 E2 3Q 2020 DT/OT Patriot flight test.  Same objective as E1?
FTP-17 3Q 2020 DT Patriot intercept test
FTP-22 3Q 2020 OT Patriot intercept test
FTP-23 3Q 2021 DT/OT Patriot flight test.
FTP-28 3Q 2021 OT Patriot intercept test
FTP-25 4Q 2021 OT Patriot intercept test
FTP-24 4Q 2021 DT Patriot intercept test
FTP-18 2Q 2022 OT Patriot intercept test
FTP-19 2Q 2022 DT Patriot intercept test
FTP-20 2Q 2022 OT Patriot intercept test


UpcomingFlights2-March 2019

Aegis SPY-1 Radar Upgrade (March 25, 2019)

The Navy plans to equip its new Flight III Aegis destroyers with its new SPY-6 radar.  The SPY-6 is made up of 37 self-contained Radar Module Assemblies (RMAs).  The SPY-6 is expected be at least 30 times more sensitive than the current Aegis SPY-1D radar (or 2.3 times the detection or tracking range against a given target).

A reader of my March 13 post noted that in the FY 2020 budget the Navy announced plans to upgrade the SPY-1D Aegis radar on its Flight IIA destroyers by replacing the current antennas and transmitters with a 24 RMA antenna, and asked how this upgraded radar would compare to the current SPY-1D radar and the new SPY-6.

Since the SPY-6 and the planned upgrade to the SPY-D will use the same radar technology, they will primarily differ only in their power, antenna area and gain.  Since each of these is proportional to the number of RMAs, the upgraded SPY-1 radar will have (24/37)3 = 0.27 of the sensitivity of the SPY-6.  However, it will have about (0.27)(30) = 8 times the sensitivity of the current SPY-1D (which is a pretty big improvement).

GMD Testing Update (March 19, 2019)

The FY 2020 RDT&E budget documentation for the Missile Defense Agency is now out, and unlike the previous year’s materials it includes currently planned quarterly dates for flight and intercept tests of the Ground Based Midcourse (GMD) system.  Through 2024 it appears that there are three intercept tests and two (non-intercept) flight tests planned.  Here they are:


Date as of May 2017

Current Date



4Q 2018

2Q FY 2019

Salvo intercept test. One CE-II and one CE-II Block I GBIs against an ICBM-range target.



4Q FY 2020

Flight test of upgraded GBI booster with selectable 2 or 3 stage capability.  It will be launched from  Vandenberg.


1Q 2020

2Q FY 2022

Flight test of Redesigned Kill Vehicle (RKV)


1Q 2021

1Q FY 2023

First RKV intercept test.


1Q 2022

1Q FY 2024

Second RKV intercept test.


The testing schedule for the RKV shows a slip of about two years.   This is consistent with the two year delay (from 2023 to 2025) in RKV deployment that was announced at the March 12 MDA press briefing on its FY 2020 budget.



MDA Briefing on FY 2020 Budget (March 13, 2019)(Updated March 14)

The Missile Defense Agency (MDA) presented their proposed budget for FY 2019 yesterday.  Although there is not yet any information about the budget posted on their website, a video of the briefing was posted today. I have put the slides shown at the briefing into a Word file, which is here: MDA-Budget_Briefing-Slides-03122019

(The first slide was not shown on the video, but it is probably just a title slide as there was no discussion of it.)

I expect that a transcript of the briefing will be available soon.  If so, I will add a link to it.

[Added March 14: The transcript is here.]

The two most interesting (to me) things I learned in the briefing:

(1) The RKV is delayed.  The development and deployment of Redesigned Kill Vehicle, intended to be more reliable than the current kill vehicles deployed on the Ground-Based Interceptors (GBIs) of the current U.S. national missile defense system, has been delayed by two years, from 2023 to 2025.  Since the RKVs were to be deployed on the 20 additional GBIs (bringing the total to 64) that were scheduled to begin deployment in Alaska in 2023, the beginning of the deployment of these additional GBIs has also delayed by two years from 2023 to 2025.

(2) The Neutral Particle Beam is back.  Much discussed during the “Star Wars” days, the state of technology at the time ultimately was shown to be far from allowing an actual neutral particle beam weapon to be built. However, in FY 2020 MDA plans to initiate a new program to develop a neutral particle beam that will “offer new kill options.”  MDA claims that this program could lead to an on-orbit demonstration as early as 2023.

New S-Band Missile Defense Radars in the Pacific (February 11 2019)

The United States is in the process of building (or selling) a number of new missile defense radars focused on coverage over eastern Asia and the Pacific Ocean.  All of these radars will operate in S-Band, which extend from 2 to 4 GHz.  These radars are the Long Range Discrimination Radar (LRDR), the Homeland Defense Radar – Hawaii (HDR-H), the Homeland Defense Radar – Pacific (HDR-P), and the Lockheed Martin Solid State Radars (SSRs) that Japan intends to buy for its two planned Aegis Ashore facilities. Most if not all of these phased-array radars will be built by Lockheed Martin using relatively new Gallium Nitride (GaN) technology.  There is little publicly available information about these radars, so there will not be much in the way of technical details in this post.  This post will also include an update on Raytheon’s new S-Band Air and Missile Defense Radar (AMDR).

The Long Range Discrimination Radar (LRDR)

A previous post discusses the LRDR up until April 2015.  This discussion picks up where that one left off.

In October 2015, the Missile Defense Agency (MDA) awarded Lockheed Martin a $784 million contract to develop, test and build the LRDR.[1]  The objective was to have the LRDR operational at Clear Air Force Station in central Alaska by 2020.  Military construction costs (including a shielded mission control facility, shielded power plant, radar foundation and a maintenance facility) will add another $329 million, bringing the total cost of building the LRDR to over $1.1 billion.[2]  However, it is typically described in the press as a $1.2 billion project.  Construction of the LRDR in Alaska began in September 2017.[3] As of March 2018, “initial fielding” of the LRDR was expected in 2020 with “operational readiness acceptance by the warfighter in the 2022 timeframe.”[4]


The LRDR: (Not) The Best Discrimination Money Can Buy? (January 30, 2019)

Almost three years ago, I wrote a blog post about the then recent announcement that the Long Range Discrimination Radar (LRDR) would operate in the S-Band of radar frequencies.  (S-Band covers the range from 2 to 4 GHz.) I found this development quite surprising. The LRDR was to be the key discrimination sensor for the U.S. Ground-Based Midcourse Defense (GMD) national missile defense system. I had been expecting the LRDR to operate at X-Band (8-12 GHz), which appears to provide a significant advantage in discrimination capability relative to S-Band. At the time, I speculated that this choice may have been made to save money, or that perhaps missile defense flight and intercept testing had shown X-Band did not provide any advantage in discrimination over S-Band in actual practice.

Now we have the answer: It was about cost. According to a 2018 article in the Johns Hopkins APL Technical Digest(The Johns Hopkins Applied Physics Laboratory led the systems engineering portion of the LRDR sensor trade studies, identified performance requirements, siting suitability and developed the LRDR element specification.):

“The choice of S-Band for LRDR was a compromise: S-Band was assessed to provide acceptable performance for much lower cost than an X-Band (~10 GHz) system at the same sensitivity and field of view. Trade study analysis indicated that although discrimination performance at X-Band would be superior, it was not sufficiently better than the performance at S-Band to justify the cost differential.”[1]

Discrimination is not only essential for any midcourse defense, it is the most difficult problem facing any such defense.  As discussed below, two recent government-sponsored studies (by the National Academy of Sciences and the Defense Science Board) had criticized the Missile Defense Agency (MDA) for not taking the discrimination problem seriously enough.  The decision by MDA to deploy the LRDR seemed to be at least a partial response to this criticism. However, while tradeoffs must often be made, MDA’s decision to accept inferior discrimination performance from the LRDR now raises the possibility that it still is not taking the discrimination issue seriously enough.

The two following sections discuss the relative discrimination capabilities and costs of the LRDR at S-Band rather than at X-Band.

Figure 1: LRDR Conceptual Drawing (Image Source: MDA)[2].

Countermeasures, Range Resolution, Discrimination and the GMD system

The most challenging aspect of building an operationally effective ballistic missile defense (BMD) system is dealing with steps (often referred to countermeasures) that a missile attacker could take to defeat the defense.  This is particularly the case for midcourse defenses with interceptors that operate above the atmosphere (exo-atmospheric), such as the Ground-Based Interceptors of the U.S. GMD national missile defense system and the SM-3 interceptors of the U.S. Navy’s Aegis BMD system. The lack of atmosphere makes it possible for attacker to implement a wide range of light weight but potentially very effective countermeasures.[3]

A 2011 report by the U.S. Defense Science Board stated that “The importance of achieving reliable midcourse discrimination cannot be overemphasized” and concluded that “Yet discrimination in the exo-atmosphere is still not a completely solved problem. Robust research and testing of discrimination techniques must remain a high priority.”[4]

A report released the next  year by U.S. National Academy of Sciences similarly concluded that “The hard fact is that no practical missile defense system can avoid the need for midcourse discrimination – that is, the requirement to identify the actual threat objects (warheads) amid the cloud of material accompanying them in the vacuum of space.  This discrimination is not the only challenge for midcourse defense, but it is the most formidable one, and the midcourse discrimination problem must be addressed far more seriously if reasonable confidence is to be achieved.”[5]

At present, there are two primary sources of data that might be used for midcourse discrimination: the infrared seekers on interceptors and surface-based (land or sea) radars.  However, an infrared seeker at best sees each object in a target complex as only a single pixel of light until a very few seconds before an intercept attempt.  For this and other reasons, the burden of the discrimination problem must fall primarily on surface-based radars.

When the GMD system was declared operational in late 2004, it had essentially no discrimination capability.  At that time, its core radar infrastructure consisted of two large phased-array radars, the Cobra Dane radar on Shemya Island at the western end of the Aleutians and the PAVE PAWS early warning radar at Beale Air Force base in California.  These radars were upgraded to give them capabilities to guide interceptors to attacking missiles and are now referred to as Upgraded Early Warning Radars (UEWRs).  Subsequently, four more UEWRs were added (in Britain, Greenland, central Alaska and Massachusetts) were added to this radar core.

The inability of the UEWRs to discriminate was acknowledged by the Government Accountability Office in 2004:

“Neither the Cobra Dane radar nor the upgraded early warning radar at Beale is capable of performing rigorous discrimination, a function acheivable only by the X-band radar. Rather, both radars will utilize common “target classification” software that enables them to classify objects as threatening or non-threatening. For example, debris would be classified as non-threatening, but objects like deployment buses and decoy replicas would be classified as threatening.”[6]

A December 2018 Government Accountability Office Report on the Cobra Dane radar indicates this situation remains unchanged today.  It states that the Cobra Dane radar can “Track” and “Classify” missile threats but cannot “Discriminate Missile Threats from Deployed Decoys” or “Determine if a Missile Threat is Successfully Intercepted.”[7]

The most fundamental reason that the UEWRs cannot contribute to discrimination is that they operate at relatively low frequencies (or equivalently, at long radar wavelengths).  The Cobra Dane operates at about 1.2 GHz (wavelength about 23 cm); the other five UEWRs operate at about 0.44 GHz (wavelength about 70 cm).[8]  These low operating frequencies limit the range resolution of these radars to 5 meters or more.  For a phased array radar, its bandwidth β is typically limited to roughly 10% of its operating frequency. The best possible range resolution ΔR is then about ΔR = c/2β, where c is the speed of light.  The UEWRs other than Cobra Dane have a bandwidth of β ≤ 30MHz.  For β = 30 Mhz, this gives ΔR ≥ 5 meters.

The range resolution is the smallest distance along the range axis (the line between the radar and the target) for which the radar can resolve separate objects (or separate features along one object.) The resolution along the other axes is typically much worse. Thus a radar with a range resolution of 5 meters or more can provide little information about the shape of a 2 meter long missile warhead or a similarly-sized decoy or other object other than that which can be gleaned from how its radar cross section varies with time. [Cobra Dane actually can provide a range resolution of about 1.1 m, but only over a very limited range of angles.  Because of its orientation Cobra Dane has never participated in a BMD intercept test.]

As the 2004 GAO report quoted above suggests, much better range resolution, and thus higher quality discrimination data, can be obtained by going to higher frequencies, such as X-Band.  For example, at X-band (~10 GHz, corresponding to a wavelength of about 3 cm), a phased-array radar can achieve a range resolution of about 0.15-0.25 meters.  With such range resolution, multiple features along a 2 meter long object (such a missile warhead) could be resolved.  Moreover, through the use of Doppler measurements, a similar or better resolution can be achieved along an axis perpendicular to the range axis, producing a 2-dimensional image of a target (and with enough time a 3-dimensional image might even be constructed).  While a capability to make such high resolution measurements would not completely solve the discrimination problem, it would clearly be a step in the right direction.

Accordingly, in 2006-2007, the MDA deployed the Sea Based X-Band (SBX) radar.  The SBX is a very large (249 m2 antenna area) phased-array X-Band radar on a self-propelled, semi-submersible sea-going platform. [9]  The SBX, which operates out of Honolulu, is optimized for long-range precision tracking and discrimination, and reportedly has a bandwidth of 1 GHz and range resolution of about 0.25m.[10]  However, the SBX was built initially as a testing asset and it has a number of serious limitations, most notably a very limited electronic scanning field of view (about ±12 degrees) that significantly limits its usefulness as an operational discrimination sensor.  (Many phased array radars have electronic scanning fields of view of about  ±60 degrees.)

Figure 2: The SBX (Image Source: MDA).

In addition, MDA operates five forward-based X-Band radars in Japan (2), Turkey, Israel and Qatar.  These TPY-2 forward-based radars are essentially the same (differing only in software and communications equipment) as the radar in each of the seven U.S. THAAD batteries.  These forward-based radars likely have the same range resolution as the SBX, but have much shorter ranges and can only view the early stages of a missile’s flight towards U.S. territory.

The LRDR will be in S-Band, which extends from 2 to 4 GHz.  The current SPY-1 radar on U.S. Aegis cruisers and destroyers also operates in in S-Band, between 3.1 and 3.5 GHz, and apparently has a bandwidth of about 300-400 MHz.[11]  It is also capable of using Doppler measurement to produce two-dimensional images. Thus, very roughly, we can expect that the LRDR will have a bandwidth about one-third and a range resolution and imaging capability correspondingly about 3 times poorer than what an X-Band version of the LRDR would have had.  This difference seems to be large enough to justify the Johns Hopkins APL paper’s statement that an X-Band version of the LRDR would have discrimination capabilities “superior” to that of the currently planned S-Band LRDR.

The LRDR: Cost at S-Band vs X-Band

MDA’s initial March 2014 LRDR Request for Information (RFI) to industry stated that it was not specifying the operating frequency band for the radar but rather was “looking for recommendations with rationale” based on tradeoffs necessary for the radar to perform its “precision tracking, discrimination and hit assessment” missions.[12]  It also raised the possibility that the radar could have a limited field of view (LFOV) phased-array antenna instead of a full field of view antenna.

According to the 2018 Johns Hopkins APL paper:

“In 2014, the MDA initiated the Long Range Discrimination Radar (LRDR) effort to identify and procure a new midcourse discrimination capability to supplement the existing BMDS.   Key characteristics of the radar include operation at S-Band (~ 3 GHz), wide instantaneous field of view to enable wide-area defense against raids, wide instantaneous bandwidth and a large suite of discrimination features to support robust midcourse discrimination, and high sensitivity to provide this discrimination capability at the long ranges required.”

This establishes two things: That the LRDR will operate at S-Band and that it will have a wide electronic scanning field of view (EFOV), here assumed to be ± 60 degrees.

Each of the two LRDR antenna faces will be populated with large number of GaN transmit/receive (T/R) modules.  For radars of this type, the T/R modules are the primary driver of a radar’s cost.

The requirement for a wide EFOV sets the maximum spacing between the T/R modules.  For an EFOV of ± 60º and a wavelength λ, the spacing between T/R modules in a square array must be 0.536λ or less in order to avoid grating lobes (essentially additional main beams).[13]  This gives an antenna area 0.278λ2 per module.  For an equilateral triangular module arrangement, the area per element is somewhat larger — 0.332λ2 per module.

For short wavelengths and large antenna faces, these module spacing limitations can lead to requirements for very large numbers of modules.  For example, the SBX’s antenna face has an active area of 249 m2.  Assuming a frequency of 9.5 GHz (λ = 3.16 cm), a square module array and an EFOV = ±60º, about 870,000 modules would have been required to fully populate the antenna array, which would have been prohibitively expensive.  In actual practice, the SBX uses a module spacing of about 2.35λ.  Together with the use of other techniques to reduce grating lobes, this spacing reduces the required number of modules to about 45,000, but at the price of a very reduced EFOV of only about ±12º.[14]

Figure 3.  The SBX Antenna Inside its Radome.  Image Source: MDA[15]

The LRDR is intended primarily for precision tracking and discrimination.  For such a radar, a standard figure of merit is its Power-Aperture-Gain (P-A-G) product. Assuming all else (noise figure, system losses, target radar cross section (RCS), etc…) is equal, an X-Band and an S-Band will obtain the same signal-to noise ratio on a target if:


where PX is the average power of the X-Band radar, AX is its antenna area and GX is its antenna gain.

Since G = 4πA/λ2 and writing the antenna power as P = N*pm, where N is the number of modules and pm is the average power per module, this becomes:

(NX*pmx*AX2)/λX2 = (NS*pms*AS2)/λS2.

Assuming the average powers of the S-Band and X-Band modules are equal (as discussed below, probably not a valid assumption) and noting the antenna area for each module is proportional to λ2, we can solve for NX:

NX = NS*(λS/λ­X)2/3.

Assuming the S-Band radar operates at 3.5 GHz (λ = 8.57 cm) and the X-Band at 9.5 GHz (λ = 3.16 cm), then:

NX = 1.94*NS.

Thus the required number of X-band modules would likely be at least twice the number of S-band modules to get a radar with equal sensitivity and EFOV.  The number of modules will be quite large, as in a subsequent post I will argue that number of S-Band modules required for both faces of the LRDR may be as great as 240,000.  The ratio of modules alone suggests that the X-Band version of the radar would cost nearly twice as much as the S-Band version.  This difference could amount to a substantial amount of money as the contract to Lockheed Martin to develop, build and test the LRDR was for $784 million.

Moreover, the actual cost ratio may be significantly higher.  In particular, GaN T/R modules are a relatively new technology compared to the GaS modules used in the SBX or TPY-2 radars.  The LRDR and the Space Fence are the first very large radars to use GaN technology (at least as far as I know).With such new technology, it is likely the average power obtainable from an S-band module will be greater than that from an X-Band module, and the noise figure at S-Band could also be lower.  In addition, over wide ranges of angles, the radar cross sections of warhead-shaped targets tend to decrease as the radar frequency increases. These factors could significantly increase the number of X-Band modules required to get a sensitivity equal to a LRDR radar using S-Band modules.

Thus it seems reasonable to conclude that an X-band version of the LRDR would cost at least twice as much as the currently planned LRDR and it could cost much more.

[1] Kenneth W. O’Haver, Christopher K. Barker, G. Daniel Dockery, and James D. Huffaker, “Radar Development for Air and Missile Defense,” Johns Hopkins APL Technical Digest, Vol. 34, No. 2 (2018), pp. 140-152.  Online at:

[2] Missile Defense Agency, “Fiscal Year (FY) 2018 Budget Estimates,” May 15, 2017. Online at:

[3] A.M. Sessler, J.M. Cornwall, B. Dietz, S. Fetter, S. Frankel, R. L. Garwin, K. Gottfried, L. Gronlund, G. N. Lewis, T. A. Postol, and D. C. Wright, Countermeasures: A Technical Evaluation of the Operational Effectiveness of the Planned US National Missile Defense System, Cambridge, Massachusetts: Union of Concerned Scientists /MIT Security Studies Program, 2000, pp 35-37, 145-148. Online at:

[4] U.S. Department of Defense, Defense Science Board, Defense Science Board Task Force Report on Science and Technology Issues of Early Intercept Ballistic Missile Defense Feasibility, Washington, D.C.: Defense Science Board, September 2011, p. 5.  Online at:

[5] U.S. National Academy of Sciences, National Research Council, Committee on Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives, Making Sense of Ballistic Missile Defense: An Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives, Washington, D.C.: The National Academies Press, September 2012, p. 10.  Online at:

[6] Government Accountability Office, “Missile Defense: Actions Being Taken to Address Testing Recommendations, but Updated Assessment Needed,” GAO-04-254, February 26, 2004, p. 17. Online at:

[7] Government Accountability Office, “Missile Defense: Air Force Report to Congress Included Information on the Capabilities, Operational Availability, and Funding Plan for Cobra Dane,” GAO-19-68, December 2018, p. 7 (Table 2).  Online at:

[8] For technical details about the UEWRs, see “Appendix 10: Sensors” of Laura Grego, George N. Lewis, and David Wright, Shielded From Oversight: The Disastrous US Approach to Strategic Missile Defense, Union of Concerned Scientists, July 2016.  Online at:

[9] For details about the SBX, see “Appendix 2: The Sea Based X-band Radar,” of Laura Grego, George N. Lewis, and David Wright, Shielded From Oversight: The Disastrous US Approach to Strategic Missile Defense, Union of Concerned Scientists, July 2016.  Online at:

[10] The SBX uses essentially the same radar transmit/receive modules as the THAAD radar (TPY-2), which has a bandwidth of 1 GHz and range resolution of 0.25 m. Philip A. Ingerwesen, William W. Camp and Alan J. Fenn, “Radar Technology for Ballistic Missile Defense,” Lincoln Laboratory Journal, Vol. 13, No. 1 (2002), pp. 109-147 (p. 141).

[11] Ingerwesen, et. al., “Radar Technology for Ballistic Missile Defense,” p. 141 says 300 MHz.  A 1999 Lincoln Laboratory briefing slide shows a “Wideband Waveform Concept for AN/SPY-1 Radar” using a 400 MHz wideband waveform constructed from ten 40 MHz bandwidth pulses frequency jumping from 3.1 to 3.5 GHz.  Eric D. Evans, “Missile Defense Technology (Can BMD Systems Work?)” Mini DTS Course, MIT Lincoln Laboratory, December 10, 1999. (40 MHz was the bandwidth of the Aegis radar when it was initially deployed.)

[12] Missile Defense Agency, “Missile Defense Agency Long Range Discrimination Radar Request for Information,” SN HQ0147-14-R-0002, March 14, 2014. See

[13] See Grego, et. al., “Appendix 2,” pp. 4-5.

[14] Grego, et. al., “Appendix 2,”

[15] Online at:

Updated Tables of Intercept Test (November 30, 2018) (Updated April 4, 2019)

This post updates my tables of intercept test for the GMD, SM-3 and THAAD systems. This updates my post of April 22, 2018, adding two additional tests for the SM-3 Block IB and SM- Block IIA.   See that post for some background information on why I started to compile these tables.  This update also adds a brief description of the cause of each intercept failure. December 11 update adds one SM-3 Block IIA test. April 4 update adds FTG-11 GMD test.



TestingGMDText-November 2018