Scientists studying pulsars as potential GPS backup

 - September 23, 2008, 6:23 AM

Operators in the future will possibly be able to use X-rays from pulsating stars–or pulsars– light years away from earth to navigate with the same accuracy as GPS.

At a recent Position, Location and Navigation System (Plans) convention in Monterey, Calif., researchers explained that pulsars are like space lighthouses, sweeping powerful beams of energy through our solar system as they spin rapidly in outer space. Those sequential sweeps are timed as precisely as the atomic clocks used in GPS. That is why, after pulsars were discovered in 1967, military scientists saw them as a potential–and invulnerable–backup to GPS in a jamming environment.

Results of their investigations have never been made public, but someone familiar with the work told AIN it is “ongoing” in the UK, the U.S. and “other countries,” understood to be Russia, France and China.

But the interest is not simply in backing up navigation from GPS or other satnav systems. Around the world, super-accurate satellite time has become the critical backbone of government and commercial activities in telecommunications, banking, transportation, utilities and countless other applications. According to the same source, protracted loss of GPS timing signals across the U.S. would be “a nationwide disaster.” It was for exactly that reason that control of loran–the now-official GPS backup for terrestrial applications, with near-GPS timing accuracy–was transferred from its former Coast Guard custodians to a specialist group within the Department of Homeland Security.

With XNav, the acronym for the pulsar X-ray-based navigation technique, the presenters at the Plans conference looked beyond pulsars’ practical application and far into the future, to when travel extends into space. The extremely low-powered GPS signals are unlikely to be useable beyond 80,000 miles from earth, scientists believe, and, even if they were, the satellites’ clustered orbits around Earth would provide progressively worse fix “geometry” as the distance from them increased. XNav would offer hundreds of navigation beacons across the galaxy.

However, civil applications of the concept are barely in their infancy, and it seems highly unlikely that any corporate pilots living today will have an XNav input for their FMS. But for the Captain Kirks of the future, some words of warning: while pulsars are valuable position finders in deep space, they would also present serious navigation hazards. Although only 10 or so miles in diameter, they are the central cores of collapsed stars, and possess extraordinary mass, with a teaspoon of their material calculated to weigh around a billion tons. Worse, they exert tremendous gravitational force, with the largest– called Magnetars–having one thousand trillion times that of Earth. Reportedly, such an object placed between Earth and the moon would “pull metal pens out of the pockets of observers on Earth.” Clearly, not a beacon you’d want to overfly directly in your intergalactic Belchfire 6000.