Ramsden Sextant


Method of the ancient mariners can improve targeting systems

The Global Positioning System has been a revolutionary tool for navigation, mapping and, in the military, for targeting weapons systems. But GPS also has its weak spots, being susceptible to jammingspoofing and other disruptions.

When GPS fails, what can military forces rely on? How about the same technique Columbus, Magellan and much earlier mariners used to navigate the seas 500 years ago — celestial navigation. Although in this case, it would be a highly refined sort of celestial navigation, involving a lot more than a sextant and prayer.

Northrop Grumman recently reached a deal with Trex Enterprises to incorporate Trex’s celestial navigation technology into the precision targeting capability it supplies to the U.S. military and allied forces. Northrop will integrate the highly accurate, multi-aperture celestial navigation system into ground laser targeting systems, which will increase precision in locating targets, the companies announced.

Celestial navigation, which involves making astronomical observations to establish one’s position on Earth, was developed over thousands of years. In its most basic form, sailors measured the angle in relation to the sun or the North Star to get a rough idea of their latitude and sailed east-west along a latitudinal line. A breakthrough came in the 18th century with the discovery of how to determine longitude, and the precision of celestial navigation systems continued to  improve with the ability to use multiple stars and time to determine location.

Celestial navigation continued to be used by ships and aircraft through the Cold War, but began to fall out of favor with the emergence of GPS. For one thing, celestial navigation involved a fair amount of math, and GPS was easier, as well as accurate.

Now, celestial navigation could be on the rise again. Trex has developed a multi-aperture stellar tracker able to detect stars during daylight, which, combined with the company’s proprietary automated star pattern recognition algorithms, can deliver accurate navigation information at any time of day. The company is already working with the Navy to develop an alternative navigation system that can operate independent of GPS.

Northrop’s plans for its laser targeting system will create another use for the technology.

Northrop’s laser target designators can be used by soldiers, air controllers or other personnel to locate potential targets, measure their distance from the lasers and relay that information to bombers or artillery units, according to Military & Aerospace Electronics. Adding celestial navigation data to that information would only increase its accuracy.

"The integration of celestial navigation technology marks an important milestone on the precision targeting technology roadmap," Gordon Stewart, vice president and general manager of Northrop's Laser Systems unit, said in the company’s announcement. "We will continue to refine and grow the application of celestial navigation for precision targeting across our production laser systems for U.S. and coalition warfighters."

About the Author

Kevin McCaney is a former editor of Defense Systems and GCN.

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