Global Positioning System
 Is a Single Point of Failure

October 1, 2012
By Capt. Charles A. Barton III, USAF

GPS vulnerabilities could be addressed with upgraded long-range navigation.

In an instant, one million people in Tel Aviv are vaporized. Hamas, the terrorist extremist group backed by Iran, has detonated a dirty bomb—a conventional explosive with radioactive material—and is attacking Israel with long-range rockets. Concurrently, the U.S. Air Force loses all communication with its Navigation System Timing and Ranging Global Positioning System satellites. Intelligence reports indicate that Iran has launched multiple antisatellite missiles that have destroyed several navigation satellites, effectively disabling the Global Positioning System.

This is a fictional scenario, but it may not be that far-fetched. The U.S. military must take into account the vulnerabilities of its Navigation System Timing and Ranging (NAVSTAR) Global Positioning System (GPS) and invest in a land-based system that provides the same capabilities.

In a 1980 report to Congress, the General Accounting Office (GAO) stated that the NAVSTAR system “was not started to satisfy unmet military needs or operational deficiencies but rather to generally improve navigation capabilities.” Nevertheless, the military soon realized the enhanced capabilities that the GPS could provide, and it “defined specific mission requirements” for the system. The plan was to launch 24 satellites, allowing for four satellites to be in “view from any spot on Earth at any time.” The system was scheduled to be 100 percent capable by September 1987 with an original cost estimate of $1.7 billion. In 1980, the GAO revised the cost estimate, stating that it would cost $8.6 billion to cover the program through 2000. In reality, the system did not become fully operational until April 1995, with an estimated cost of between $10 billion and $12 billion. Additionally, Air Force officials stated that it would cost approximately $400 million annually to provide the GPS. Ultimately, the cost of the GPS was six to seven times more expensive than originally planned, and it was deployed with known vulnerabilities.

The system is open to attack from several different means, including antisatellite (ASAT) missiles, electronic warfare through jamming and network attack. In the 1980s, the United States and the Soviet Union both were testing ASAT weapons to bolster their military posture during the Cold War. The United States stopped testing in 1985 due to its concern that space junk could damage other satellites. Furthermore, 99 nations signed on to the 1967 Outer Space Treaty that was designed to prevent “the stationing of weapons of mass destruction in outer space.” Many countries argued that the treaty did not go far enough because it did not specifically ban other types of conventional weapons.

Nevertheless, the treaty seemed to have an effect because no weapons openly were fired into space for 22 years. On January 11, 2007, China shocked the world by shooting down one of its own weather satellites using a ground-based medium-range ballistic missile. The event was condemned by several countries—including the United States, Japan and Australia—over fears that it would start a new space arms race. The United States could not allow this show of force to go unanswered. On February 21, 2008, the United States fired a Standard Missile-3 from the ship USS Lake Erie in an “effort to shoot down an inoperable spy satellite before it could crash to earth and potentially release a cloud of toxic gas,” CNN reported.

Coincidentally, the United Nations Conference on Disarmament was in the middle of its first session for 2008. Seven days after the spy satellite was shot down, China and Russia submitted a joint treaty on the “prevention of the placement of weapons in outer space” and the “threat or use of force against outer space objects.” The United States argued against the need for additional treaties on the grounds that there was not an ongoing arms race in space.

Ironically, the tests by China and the United States did compel other countries such as Russia and India to start developing similar ASAT weapons. In March 2009, one of Russia’s deputy defense ministers stated that Russia would begin developing its own ASAT weapons in addition to bolstering its nuclear and intercontinental ballistic missile systems. India followed suit in May 2010 by stating it would develop ASAT weapons capable of attacking satellites in both low earth orbit and geosynchronous orbit. These statements make it abundantly clear that U.S. GPS satellites no longer could rely on altitude for safety.

Additional concerns are that GPS capabilities could be rendered useless with certain types of electronic warfare jamming equipment and network attack. An example of GPS jamming occurred in 2009 when engineers at Newark Liberty International Airport, Newark, New Jersey, noticed their equipment would lose signal during certain times of the day. The Federal Aviation Administration (FAA) investigated the problem and found that a local truck driver had installed an inexpensive jammer in his vehicle. On his way to work every day, he passed the airport and caused its systems to fail. The driver was using the jammer to prevent his employer from tracking his movements. The scary fact is that anyone can purchase this equipment for as little as $30 on the Internet. Even though these jammers are illegal to sell, purchase or use, people still buy them.

Another instance occurred in January 2007 during a U.S. Navy training exercise in San Diego. The Navy was evaluating its ability to operate ships in a situation with total loss of communications. To test this, it used jamming equipment to block all radio signals. The Navy unintentionally blocked all GPS signals in the San Diego area, causing FAA systems, cellphones, pagers and automated teller machines to fail. This type of jamming easily could be used by a foreign military or terrorist organization to cause chaos.

A recent example of this happened in late 2011 when Iran’s military claimed it brought down a U.S. unmanned drone using GPS jamming in conjunction with a computer attack. It jammed the drone’s GPS signal to force it into autopilot mode. Then, the Iranian military used a computer attack to spoof the GPS signal, making it appear to the drone’s computer that it was headed to a U.S. base when it actually was being routed to an Iranian location. Some researchers have acknowledged the plausibility of the Iranians’ story. The reality that the drone looks undamaged lends credibility to their claims. The fact that experts believe the Iranians’ story to be possible provides evidence that the military’s GPS is susceptible to attack.

This is another example proving that the GPS system is vulnerable. The U.S. military must take a hard look at all solutions that would provide a redundant capability. One such possibility is a system known as long-range navigation (LORAN). This system was developed in 1958 to provide navigation for shipping. It uses powerful signal pulses at a low frequency and is not line-of-sight dependent. Consequently, LORAN does not have the same vulnerabilities as the GPS. However, on February 8, 2010, the U.S. Coast Guard stopped the LORAN transmissions, effectively retiring the system. Even though LORAN was retired, researchers at Stanford University and the U.S. Coast Guard continue to develop a 21st-century model.

The project is known as eLORAN. It provides the added capability of a data channel plus vastly improved accuracy. For example, LORAN was accurate to approximately 460 meters, while eLORAN is accurate to between 8 and 20 meters. This is comparable to most handheld GPS receivers, which are accurate from 10 to 20 meters. The U.S. military has receivers that are accurate to less than one meter. eLORAN’s accuracy will need to be developed further to provide the same military GPS capability.

The United States needs to invest additional funding into this system to develop its viability as a backup to the GPS. However, the greatest argument against any new system is its cost. Currently, the U.S. military is looking at a budget reduction of $500 billion. Some critics suggest this may have the unintended consequence of reducing scientific innovation. The military spent approximately $81.4 billion on research and development during the last fiscal year. This accounted for 55 percent of the federal government’s research and development funding. History shows that military research and development is cut at the same percentage as budget reductions. Fiscal hawks will argue that the military does not require a redundant capability for the GPS. On the other hand, the U.S. National Security Strategy report states that the U.S. military must preserve its “conventional superiority.”

Scientific innovation is exactly what is required to develop a redundant capability for the GPS. It is blatantly obvious that the GPS is highly vulnerable, and the United States must prioritize funding for research and development of a comparable system. eLORAN is one possible solution to this problem. The Defense Advanced Research Projects Agency (DARPA) has a history of “50 years of innovation and discovery.” DARPA should be assigned as the lead for this project, and it should fund a competition so that multiple organizations will design a solution. The possibilities are endless if the Defense Department is willing to make it a priority.


Capt. Charles A. Barton III, USAF, is the chief of plans and programs at the 689th Combat Communications Wing, Robins Air Force Base, Georgia.


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GPS vulnerabilities are well understood and there are ways to mitigate these vulnerabilities. Bringing LORAN back to life is not the answer. First, there are no free lunches. For many applications, directional antenna technology holds great promise to negate jamming. Second, timing technology is now at a level where direct precise signal acquisition can be the new procedure rather than a CA handover. Initeral technology and geoid modeling have reached a point where autonomous accurate navigation is feasible for long periods of time. Further, our communications architectures also enable PVT. The trick is integration, integration, integration.... In terms of ASAT threats, this integration will be our backup, and it is important to understand that when a conflict begins in space and/or space becomes one of the battlefields we are no longer dealing with asymetric or third world threats it is now a full dimensional and we will be fighting for our survival and very possibly the the conflict will result in the unspeakable, nuclear exchange(s). It is in this last context, that I continue to advocate integration, integration, integration.

Interesting story. But the lead-in fictional scenario doesn't help bolster the author's credibility. No way would a "dirty bomb" vaporize anything in an instant, except for perhaps the immediate vicinity, and that would be dependent upon the amount of conventional explosives used. Please do your homework next time if you don't want readers to ignore your article because of completely presposterous scenarios.

This excellent article by Capt. Charles A. Barton III, USAF, contains a misstatement that requires a correction. While I cannot speak on behalf of Stanford University, I can confirm that the U.S. Coast Guard is not conducting any further research into loran or developing a 21st-century model for loran.

Mike Sollosi
Office of Navigation Systems
U.S. Coast Guard

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