New Technology Could Improve Inertial Guidance System Accuracy

February 1, 2013

NASA has tapped a team of aerospace, military and academic researchers for a three-year project that could dramatically improve in-flight navigation capabilities for space vehicles, military air and sea assets, and commercial vehicles. The project, “Fast Light Optical Gyroscopes for Precision Inertial Navigation,” is intended to enhance the performance of a vehicle’s inertial guidance system by refining the optical gyroscopes that drive it. These highly sensitive gyroscopes, paired with accelerometers, measure a vehicle’s attitude or orientation based on its angular or rotational momentum in flight, and track its velocity and acceleration to precisely determine its position, flight path and attitude.

Gyroscope-based inertial guidance systems are nothing new; American rocketry pioneer Robert Goddard developed elementary gyroscopes for his launch tests in the early 1900s. The technology later was adapted to serve a range of high-tech spacecraft, guided missiles and commercial aviation. But researchers supporting the new project say their sophisticated new optical gyroscopes could be at least 1,000 times more sensitive than current gyroscopes – even in this initial prototype demonstration. That’s a critical leap forward as the nation plans new robotic and crewed missions into the solar system. Even the best modern spaceflight navigation systems can suffer from accumulated “dead reckoning” errors – positioning miscalculations that result when an absolute point of reference, or a fixed “landmark” in space, is not readily available. To correct for such errors, flight operations personnel must rely on backup technologies, including Earth-based systems such as a global positioning system, or GPS. But such measures often lack the precision or uninterrupted flow of data needed to make critical course adjustments or maneuvers.

Enter the Fast Light Optical Gyroscope project team, who are investigating the use of optical dispersion, or the manner in which different wavelengths, or “colors,” of light travel at different speeds through a material, to manipulate the sensitivity of the gyroscopes’ optical cavities. In certain materials, such as the atomic gases the team is studying, this dispersion can cause pulses of light to travel faster than the speed of light in vacuum. This phenomenon, known as “fast-light,” can increase the sensitivity of a gyro’s optical cavity, allowing it to more precisely measure how fast a spacecraft is rotating – the crux of accurate and reliable inertial navigation data.

The team anticipates initial laboratory demonstration of the new gyroscopes by early 2014, with field tests in 2015.