Friday, July 13, 2012

GPS - The Navy's Addiction

GPS - Achilles' Heel?

One of the simultaneous strengths and weaknesses of modern missiles, UAVs, and weapon systems and platforms in general is the use of GPS (Global Positioning System).  The common GPS that is part of our cell phones and automobile navigation systems among other commercial devices is also at the heart of the targeting systems of military weapons.  GPS, both commercial and military, is provided by satellite systems.  Unfortunately, those satellites are vulnerable to destruction and jamming.  For example, it is generally assumed that GPS satellites will be taken out early in a war with China.  If that were to happen, it would render the Navy’s missiles useless or, at least, severely degraded with only Inertial Navigation Systems (INS), which are far less accurate, to fall back on.

On a related note, the Navy now relies so heavily on GPS for ship movement and location that most ships would be lost without it.  In fact, the USS Port Royal grounding was due, in part, to loss of GPS and the resulting lack of awareness of their location.

Here’s a portion of a recent article from Katie Drummond that highlights the issue. (1)

“In an effort to stave off the looming threat of GPS attacks, the Pentagon's asking for ideas to replace the system ... or at least give it some slicker, more reliable back-up.

The navigational system used by the military for just about everything from guiding drones to dropping bombs is increasingly under threat of attack. Now, the Pentagon’s desperate to replace it. Or, at least, reinforce it enough to stave off a looming storm of strikes.

That’s the thrust of a new venture from Darpa, the military’s premier research arm and the brains behind GPS’ initial development in the 1950s. On Tuesday, the agency announced the second phase of their program, “All Source Positioning and Navigation (ASPN),” that’s trying to “enable low-cost, robust and seamless navigation solutions … with or without GPS.”

The program, which Darpa quietly kicked off last year with two awards for theoretical research, is one part of a larger military effort that’s trying to steer the Pentagon away from its GPS dependency.

Why? First off, there’s the growing risk of GPS signals being jammed by adversarial forces. Enemies on the ground can also “spoof” a GPS system — essentially tricking it into showing an incorrect location. And these are far from hypothetical risks: Mere weeks ago, a fatal drone crash in South Korea was attributed to GPS signal jamming from north of the border. Last year, Iranians (perhaps dubiously) claimed they jammed the GPS signals navigating an American spy drone, then spoofed the system to land in Iran’s clutches.

And those GPS-thwarting capabilities continue to grow — at a pace that’s exceeded the military’s ability to keep pace — largely because of a booming commercial market for GPS-jamming technology. Such electronic warfare “was once the province of a few peer-adversaries,” Darpa deputy director Ken Gabriel told the House Armed Services Committee’s panel on emerging threats earlier this year. “It is now possible to purchase commercial off-the-shelf components for more than 90 percent of the electronics needed in an [electronic warfare] system.”

The risks now inherent in GPS are well-known, but it doesn’t look like Darpa’s ready to give up on the system altogether. Instead, they’re after a navigational system that can swiftly move between different combos of devices, using a “plug-and-play” approach. Right now, the agency notes, the military’s navigation systems primarily rely on a pairing of two devices: GPS, which uses satellite data, and what’s known as an Inertial Navigation System (INS), which relies on “dead reckoning” (using estimates of speed and direction, without external references) to provide locational intel.

It’s a tactic that’s accompanied by several problems. For one, INS — because it uses internal, ongoing estimates — is notoriously error-prone without a GPS system to back it up, so it can’t be relied upon exclusively. And INS systems often obtain their starting position and velocity from a GPS device. Which means if the GPS is under attack, the INS risks leading military personnel (or the drone or weapon they’re navigating) astray.

These navigational systems are also extremely inflexible. Typically, Darpa notes, they’re programmed to accommodate, maybe, one additional sensor (say, a magnetometer) and unable to plug into any others. As a result, personnel can’t respond to “new threats or mission challenges” in real time. Not to mention that, even as consumer navigation tech becomes more sophisticated (Apple Maps, anyone?) the military can’t take advantage of the most cutting-edge products.

Of course, there are already plenty of GPS alternatives available. Radio beacons, which transmit signals from static locations to receiving devices, allow the calculation of location based on proximity to various beacons. Ground feature navigation extracts the positions of tracked objects and then uses them as points of reference to gauge a vessel’s locale. And stellar navigation systems use the coordinates of celestial bodies to assist in a vehicle’s navigation.

Darpa’s dream navigational system would go beyond those kinds of discreet systems — by incorporating pretty much all of them. The ASPN system, according to Darpa’s announcement, should be able to accomodate any available sensor, and be versatile enough to incorporate new sensors “as they become available in the marketplace.” The key benefit to such adaptability would be the mitigation of GPS-dependency. Personnel would instead have myriad sensors at their disposal, and be able to toggle between them as necessary. In other words, a suite of backup tools to work, in conjunction, as a safety net in case of GPS failure. Among the ton of gadgets that Darpa wants the system to utilize: 3-D imagers, LiDAR, temperature sensors … and good old compasses.”

The Wave of the Future?

As an example of the military’s recognition of the inherent weakness in depending on GPS, DARPA awarded a contract to Lockheed Martin to develop a next generation anti-ship missile, the Long Range Anti-Ship Missile (LRASM) which will be able to target without using GPS.

The Navy needs to wean itself off its dependence on GPS or risk finding itself with lost ships and non-functional weapons at the start of the next war.  Anyone got a sextant?

(1) “When GPS Goes Down, Pentagon Still Wants a Way to Fight”, Katie Drummond, June 13, 2012


  1. I think new GPS systems and technology are great for the Military and Navy. They have been doing some great things with these systems and have improved a lot of their equipment with them. However, they have been having some problems like GPS spoofing. Fortunately, the accomplishments of SAASM has been able to help with these situations.

    1. John, the link is to a generic company website. I don't recognize the SAASM acronym. What are you referring to?

      Also, no amount of improved GPS equipment will help if the satellite system is destroyed in a major conflict.

    2. Part of this chapter has details on alternatives to GPS.


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