America's complex and costly ballistic missile defense programs regularly make the news, and although land based interceptor launch sites or AEGIS equipped Navy ships get the spotlight, few know of the small fleet of highly specialized sensor ships that have made this controversial technology possible.

Whether the focus of a test is shorter ranged theater ballistic missiles or long-range intercontinental ballistic missile with multiple reentry vehicles (MRVs), or even one of our own, we cannot properly learn how to counter or improve them without incredibly accurate and detailed telemetry data. Since ballistic missile tests occur over vast expanses of ocean, fixed-based radars are not ideal for the tracking job. This is where the DoD's pocket fleet of highly customized tracking, test and ballistic missile defense (BMD) support ships comes in to play, some of which have shadowy front-line duties as well.

USNS Howard O. Lorenzen


The newest and most powerful missile tracking ship is the USNS Howard O. Lorenzen. This 534-foot long bright white beast packs a pair of state-of-the-art "Cobra King" active electronically scanned array (AESA) radars that are each the size of a three story building and weigh half a million pounds each.

The Howard O. Lorenzen and her Cobra King radars were developed to replace their extremely successful but dated forerunner duo, the USNS Observation Island and her Cobra Judy phased array radar system. The Cobra King represents a vast improvement in resolution, agility and power handling, and it is said to be more easily upgradable over time, which will hopefully give the Howard O. Lorenzen a long service life like the Observation Island had.


The Cobra King system included two AESA radar arrays, one in the S band and one X band, that are both controlled via a common operations control station. The S Band array is used for scanning large volumes of sky for objects and for tracking missiles in flight, while the X band array is used for zeroing in on small hard to detect objects like reentry vehicles, missile interceptors, or even tiny satellites. The X band AESA array is especially important as it can help differentiate warheads from decoys, and this data can be used to build software for less capable systems to do the same. In many ways, Cobra King works in a similar fashion to the Navy's soon to be deployed Air and Missile Defense Radar (AMDR), which also has two separate radar arrays, one for X band and one for S band, for volume search and precise tracking. The AMDR will first be deployed on Nuclear Carrier the USS Ford.

Sea Based X Band Radar (SBX-1)


The giant SBX-1 is one intimidating contraption. She is built around the frame of a self propelled, semi-submersible drilling platform that can re-position itself anywhere in a hemisphere if need be. Ironically, the self propelled platform that houses the the SBX-1 radar was originally built in Russia before being bought by Boeing and refitted in the US for its current use.

Inside of its massive white inflatable dome is a four-million-pound X band phased array radar system. This massive piece of radiating technology was designed to provide incredibly detailed tracking of enemy intercontinental ballistic missiles and mid-course updates for ground-based interceptor systems.


The radar is so powerful and features such a high degree of resolution, that it can differentiate between decoys and warheads during a missile's mid-course separation phase of flight better than any other radar system out there. The information from it is data-linked to command and control stations where a decision will be made to commit interceptors to the missile if its trajectory is deemed a threat. It can then provide highly precise telemetry of those threatening objects to missile interceptors as they ascend toward their target. The system also provides kill assessment data after an intercept has occurred.

The SBX-1 radar is so powerful that Lt. Gen Obering, at the time the director of the Missile Defense Agency, said that the system is able to track an object the size of a baseball over San Francisco from Chesapeake Bay in Virginia, which is approximately 2,900 miles from radar to target!


SBX-1 is based up at Adak Island in far western Alaska but she can be re-positioned based on the threat or test at hand, and has done so in the past during missile defense tests and heightened tensions with North Korea. The ability to quickly re-position the SBX-1 is key as it can position itself along the most probable flight paths of hostile missiles. She is often seen in Hawaii for operations and tests or getting serviced in Seattle.

SBX-1 is both an operational capability and a technology demonstrator, and as America's ballistic missile defense capabilities continue to evolve other SBX platforms may be deployed to different regions so that a persistent network of mid-course commit and differentiation systems can cover large swathes of airspace around the globe.

USNS Invincible


USNS Invincible was once as sonar array towing ship and is roughly half the size of the Horward O. Lorenzen. She was refitted in the 1990s and the dish-style "Cobra Gemini" radar system was mounted on her stern, as well as a command center and satellite communications systems.

Cobra Gemini can work in both S and X bands as well, but not with any anywhere near the power or agility that the Cobra King can, which is not necessarily a handicap considering that this radar system is intended for tracking theater ballistic missiles which have a much shorter range than ICBMs.


Seeing as short and intermediate ranged ballistic missiles have become a serious threat around the globe, especially in relation to Iran and North Korea, USNS Invincible's ability to closely track their launches makes it a ship that is in extremely high demand.

Range Safety Ship Worthy & The MV Pacific Collector


The Worthy is operated in conjunction with the US Army and is used as a remote range safety and control ship via the installation of the "Kwajalein Mobile Range Safety System (KMRSS)." This system offers telemetry during the early stages and mid-course period of a missile's launch and allows for monitors to assess the quality of the missile's flight path. If the missile appears to be going astray, it can order a self destruct of it so that it doesn't wander outside of controlled airspace.

Worthy is often deployed far out to sea on medium duration missions where it will coordinate range sanitizing before and during a missile test, while also monitoring a launch within its forward deployed line of sight "window." This is the area before the missile is picked up by more sensitive tracking systems placed downrange.


The MV Pacific Collector works as mainly as a "downrange" asset for closely monitoring the telemetry of ballistic missiles in flight. Under one common concept the two ships work closely together with the Worthy clearing the range during the missile's boost and mid-course stages of flight and tracking the vehicle before passing off the tracking mission for the mid-course and terminal phase of the missile's flight to the MV Pacific Collector. These ships can supposedly be mixed and matched with various other test assets as well depending on the test goals and the capability of the missile being tested.

SS Pacific Tracker


The conversion of a 50-year-old cargo ship to one of the most advanced radar telemetry ships in the world is an interesting action to say the least. Before she was re-christened into her new role in 2009, Pacific Tracker had multiple prior careers, and many names to go along with them. These include Mormacdraco, American Draco and the USNS Beaver State. Now this steam driven relic boasts a massive state-of-the-art X band radar on her stern along with a state-of-the-art communications and data-link system.

This new radar comes with a new name, XTR-1 for X band Transportable Radar One. The capabilities of this new array are less than clear, but they are unique and powerful enough to have have a whole ship refitted around them. The ship also packs a pair of additional tracking arrays mounted amidships but they pale in comparison to the the size of the XTR-1.


This long and lean floating antique has already taken part in multiple tests and if improvements made to her radar arrays and antenna are any indication, she seems to be rapidly adding capability early in her new life. Still, the ship's exact role is unknown, and there has even been speculation of a possible use by a foreign power. What is more likely is that she is just another floating radar outpost that can be used for monitoring ballistic missile launches and missile tests.

USS Tripoli

I know what you are thinking, how is a long-retired hulk of an amphibious assault ship somehow a missile test and sensor ship? Well, strangely enough, the Tripoli's story, as it was featured on my old website, is one of abandonment and adoption, a phoenix that rose from the scrapper's torch if you will:

The USS Tripoli was first commissioned in 1966 and proudly served as an integral member of America's "Gator Navy" for three decades. Among her many accomplishments were three tours off the coast of Vietnam and acting as a test carrier for the Marine's new (at the time) AV-8A Harrier jump jets. She was also the test carrier for the experimental XV-15 which would lead to the development of the MV-22 Osprey, and operating as the flagship for crucial counter-mine operations during the buildup to Operation Desert Storm, during which she was actually struck by a mine.

By 1995 the Navy and Marines required updated amphibious surface combatants, namely those with modern sensors, well decks for deploying hovercraft and beach landing craft, as well as a flattop for launching helicopters and Harriers. With this in mind, and considering the Tripoli's age as well as the end of the Cold War, the Navy retired the proud ship.


A decade later, the USS Tripoli, now a rusting hulk that had been long docked at the Mare Island shipyard in Vallejo, was mysteriously transferred "on loan" to the US Army. Activity started to sprout up around the once all but abandoned floating giant and she began to receive peculiar modifications to her deck and island structure. Large temporary (but often permanent in actuality it seems) clam-shell hangars were erected on her flattop, similar to the ones seen all over US bases in the Middle East, and her island structure began to receive new aerials and communications domes. Then, in 2006, she was towed out of port and across the Pacific to Hawaii. Here her new and highly unusual purpose would come into focus.

Ballistic Missile Defense development was in full swing during the heyday of the Bush Administration and these new multi-billion-dollar systems needed to be tested under real world conditions. Seeing as BMD capability was increasingly fulfilled by upgraded AEGIS equipped Destroyers and Cruisers, and a land based system called THAAD, there was a demand for a location to act as a simulated enemy launch site for short to medium range ballistic missiles to adequately test these emerging systems.

Building a site in Hawaii, where a large portion of the theater ballistic missile defense tests were to take place, was almost totally out of the question. Even if the DoD could get approval for the construction of such a site it would cost millions of dollars a year just to maintain it. So, the DoD decided that a laid-up old flattop was the best and most cost-effective option available. That flattop being the rusted but stout USS Tripoli.


After being towed out of San Francisco bay, the USS Tripoli stayed in Hawaii for two years performing various test launches and tracking missions in support of America's Ballistic Missile Defense initiative before she was towed back to her stateside berth in 2008. In 2010 she headed back to Pacific Missile Range Facility off the coast of Hawaii to support the Theater High Altitude Are Defense (THAAD) anti-ballistic missile system, once again primarily playing the "adversary" missile launch site, known as the Mobile Launch Platform, as well as acting a mobile sensor platform to support other ongoing BMD tests.

Today, the ship has been highly revitalized and extensively modified for her unique new role. She has a fresh coat of paint and sports a multitude of sensors and communications balls, aerials, dishes and other sensor installations, along with her deck mounted retractable clam-shell hangars. The USS Tripoli's resurrection is truly a great example of how the DoD and other US agencies can recycle an old antiquated asset, that is already paid for, to do some very unique and high-tech work at a fraction of the cost of procuring a new purpose-built ship or outfitting a less flexible land-side installation for such tasks.

Considering her historical use as a test platform during her active career, I can hardly think of a more suitable role for this old, but now incredibly valuable juggernaut of the high seas.

In the end the USS Tripoli escaped the scrapper's torch while still providing invaluable service to her country and staying true to her proud motto"Semper Princeps"Always First


It all needs to work together...

What is most interesting about the hodgepodge of ballistic missile defense test and tracking ships is that some of them may also offer an operational function for the Missile Defense Agency.

BMD is not based around a single set of technologies, such as an AEGIS class Destroyer and a single radar system like the gigantic SBX-1 alone, at least not yet. Instead, BMD, especially when it comes to long range intercontinental ballistic missiles, leverages a cocktail of different capabilities and sensor platforms. What this means is that ships like the Pacific Collector, Howard O. Lorenzen, Invincible and the SBX-1 could be activated to provide data for real world intercept operations.


The idea is to use a plethora of sensor platforms, scattered along a potential missile's flight path, to build a high quality and overlapping picture of the threat posed. If the missile is deemed a threat an interceptor or two or three may be committed to countering it. If it is not deemed a threat, it can be left to fall into the sea. This classification takes highly accurate data that is transferred at near instantaneous speeds.

Instead of building extremely expensive permanent radar installations all around the globe, like we did with the massive Cobra Dane radar systems during the Cold War, miniaturization and improvements in technology have allowed powerful sensors to be put to sea, or when it comes to detecting and countering shorter-ranged theater ballistic missiles,they can be transported on land. Having mobile sensors means you can relocate your assets as they are needed based on what threats exist and they are much harder to destroy via bombardment or jam as their location is not fixed in any permanent way. In other words, the enemy has to find them in a very big ocean in order to neuter their capabilities.


Additionally, these radar systems really don't care what type of ship they are put on, so more could be fielded or conversely retired as needed. Multiple sea based ballistic missile tracking sensors also allows for redundancy should one telemetry stream fail. This could be because of a lost data-link transmission, or a power failure, not necessarily a broken radar array.

This expensive and complex "cocktail" of technologies work together via data-link to provide a high-resolution continuous picture of ballistic missiles throughout their various phases of flight. As these systems evolve, test ships that are known to monitor controlled missile tests may be able to take part in monitoring actual missile launches during times of great tension. In some ways, they already do this via monitoring test launches of other nations for intelligence and treaty verification duties. But having them on standby if a real launch may be imminent is a serious possibility.


Hypothetically, an ICBM launched from a country in the Western Pacific region may first be noticed during its hot boost stage by Spaced Based Infra-Red System (SBIRS) satellites, which quickly alerts the entire BMD network where the launch is occurring and cues the nearby Pacific Collector and an AEGIS Destroyer's radar systems to the ascending missile as it rises over the horizon. Within seconds, the AEGIS Destroyer realizes it is out of range and cannot produce a firing solution in an effort to take down the powerful and rapidly ascending ICBM.

As the missile comes out of its boost stage the Space Tracking and Surveillance System (STSS), a constellation of small low-earth orbit satellites that can track cool bodies in flight as they travel exo-atmospherically, begins tracking the missile using infrared sensors along with Pacific Tracker's powerful radar. This information is fused together to create a single high-grade track of the missile for all "players" on the ballistic missile defense and early warning network to see.


Once Pacific Tracker's radar begins to lose contact with the missile, the giant SBX-1, floating a few hundred miles north of Hawaii, comes online and using the Pacific Collector and STSS's tetelemetry it instantly points its immensely powerful radar in the right piece of sky to track the missile and differentiate decoys released by it so that the warhead's true track can be determined.

Now, with the missile thousands of miles downrange, the SBX-1 and the STSS space network alone are relaying critical tracking data to all players, including Missile Defense Agency headquarters and the Pentagon.


Howard O. Lorenzen, floating 500 miles off the coast of the California, rapidly scans for reentry vehicles with its S band radar, while also validating SBX-1's decoy differentiation data with its other X band radar and cross-checking it with the STSS data that continues to pour in. The Lorenzen, along with all other player's telemetry is passed off continuously to the MDA and Vandenberg AFB, where two interceptors are committed to knock down the incoming missile before its multiple reentry vehicles have a chance to separate.

The interceptors are launched out of California and guided directly at the incoming ICBM via data-linked midcourse updates provided by the Lorenzen and SBX-1. As the interceptor approaches at a combined closure speed of many thousands of miles per hour, the first interceptor's hit-to-kill vehicle is released but has an infrared seeker failure as it approaches the incoming warhead. The second interceptor's kill vehicle successfully releases, tracks and pulverizes the ICBM 1200 miles off the coast of California.


Now, in another hypothetical scenario, a rogue state in the Middle East is about to "test" a series of intermediate ranged ballistic missiles (IRBMs). The launches are detected by SBIRS satellites and the USNS Invincible, floating in the Persian Gulf, uses its S band radar function to search for the missiles in the direction that the satellite's infrared sensors spotted the missile's hot boost plume. Invincible identifies four targets on on a trajectory indicative of an intermediate range ballistic missile (IRBMs), and switches to X band radar mode in order to precisely track the IRBM's as they go cold following the hot boost stage which turns out to be very important as the STSS system in orbit has a malfunction and cannot track any of the targets as they level off at high altitude.

Invincible's data is being passed off and fused with a nearby Navy AEGIS Destroyer's radar picture. One of the missiles has now gone astray and self destructed and three remain heading toward strategic targets on the Arabian Peninsula. The AEGIS Destroyer commits a pair of SM-3 interceptors to each of the three missiles and fires them in rapid salvos. Moments later two of the missiles are confirmed destroyed, the remaining missile, a more advanced IRBM, released decoys and both SM-3s assigned to it have missed.


While all this has been occurring, a land-based transportable AN/APT-2 THAAD radar and PAC-3 Patriot Missile Battery has been put on high alert and is monitoring the missiles progress as it begins to descend their way. As the warhead separates a salvo of two Patriot Missile interceptors streak from their launch containers. Moments later the first interceptor obliterates the incoming warhead, while the second Patriot is destroyed on command by its operators.

Testing conditions and the real world are two different things...

The scenarios described above are just a couple somewhat idealized hypothetical situations that illustrate just how all these components could work together beyond testing and monitoring purposes. Although these narratives hopefully reflected how many disparate systems come into play just to intercept one ballistic missile, they were superficial at best and did not go into all the command and control and communication systems that have to be brought to bear successfully in order to metaphorically knock down a bullet with a bullet hundreds of thousands of feet above the surface of the earth.


Eventually, fewer telemetry sources will be needed to accomplish a successful intercept, but for the foreseeable future, when it comes to long-range ballistic missiles, redundancy and overlapping tracking coverage seem to be more of a necessity than a luxury.

The Invincible, for instance, has been seen making its way into the Persian Gulf before under Navy escort, and other key missile tracking assets get deployed when other nations are testing ballistic missiles, especially if they have hostile relations to the US. Part of these deployments are to monitor how a potential foe's missile test goes and to collect data on their ballistic missile designs and developmental progress. The other part of these deployments is to provide operational telemetry for America's Missile Defense Agency, should the test missile in question actually end up being a real missile with a real target.


Although all the ships, radars, interceptors, satellites, command and control, and communications systems that support Ballistic Missile Defense are technological marvels in their own right, they are also are evidence of just how complicated and fragile the overall system is.

It appears that redundancy is slowly being built into the system, thus addressing the very relevant age old adage "you are only as strong as weakest link." Some analysts see promise in theater ballistic missile defense, such as the Destroyer, Cruiser and now land based "AEGIS Ashore" system, as well as the land based THAAD system. Yet when it comes to long-range ICBM defense, the big land-based interceptors and lumbering radars that support them seem to be more questionable as to their true effectiveness against a capable foe.


There is little doubt that Ballistic Missile Defense will end up proving to be a reasonably effective capability, even against long-range ICBMs. The only question is how many more billions of dollars and how many more decades will it take to make it so?

In the meantime, we can marvel at the strange, almost other-worldly looking radar-packing leviathans of the sea that have come as a result of America's seemingly never-ending endeavor into creating a true missile defense umbrella over the homeland and our allies abroad.

Pictures via DoD, Industry, and shots of the Lorenzen, Pacific Collector and Pacific Tracker via our good friend and photographer Paul Carter. You can see more of Paul's great aviation and defense photography here.


Tyler Rogoway is a defense journalist and photographer that maintains the website Foxtrot Alpha for You can reach Tyler with story ideas or direct comments regarding this or any other defense topic via the email address