• Enables autonomous and uninterrupted operation: Because the GPS-MAGNAV system uses a magnetometer in addition to GPS, it eliminates GPS initialization delays and dropouts as well as requires no ground data or processing.
  
  
• Reduces cost: This system eliminates the need for expensive gyroscopes or star trackers and, therefore, significantly reduces costs for navigation systems.
  
  
• Reduces weight: Another benefit in eliminating the need for gyroscopes is that the overall system weight is reduced.
  
  
• May enable nanosatellites: The reduction in weight, coupled with the system’s comprehensive, self-contained operation, may also enable further development of micro or nanosatellite systems.
  
  
• Reduces power requirements: Processing orbit and attitude solutions using a single algorithm and with lower weight components results in reduced power consumption.
  
  
• Expandable: Additional ports can also be added to the system to allow input from other types of sensors including sun sensors and horizon sensors or gyroscopes if necessary.

• Low Earth Orbit Satellites (e.g., either prime or backup navigation system)
• Micro/Nanosatellite systems
• Marine navigation (potential)
• Aircraft navigation (potential)

The GPS-MAGNAV system was originally developed at NASA Goddard Space Flight Center for low earth orbiting (LOE) satellites.

Alone, GPS can provide accurate orbit estimates and coarse attitude and rate estimates. If combined with a gyroscope or star tracker, GPS can also provide improved attitude and rate estimates but with an increase in power, mass, and cost. Drawbacks to GPS are the initialization delays and signal dropouts that can be experienced that require backup systems in order to fill in data.

Magnetometers, which can be used to determine orbit and attitude based on the Earth’s magnetic field, are typically used with sun sensors to provide attitude estimates. There can be periods, however, when sun data is not available. By combining GPS with a magnetometer these problems are eliminated, and a more robust and accurate navigation system is created that takes advantage of the estimation qualities of both types of measurement.

Based on modeling, the GPS-MAGNAV system is capable of positional solutions accurate to less than 100 m, velocity solutions to within 10 cm/sec, attitude solutions to within 0.5 degrees, and angular rates to within 0.0005 deg/sec.

How it works

The technology combines a GPS-based system with a reliable and low-cost magnetometer and processes orbit and attitude solutions using a single algorithm. This self-contained unit performs autonomous navigation with three primary components: a processor card to host the navigation algorithm, a magnetometer card, and a GPS card. The algorithm used is an extended Kalman filter (EKF) that is combined with a “pseudo-linear” Kalman filter algorithm.

Why it is better

By utilizing a magnetometer, no ground data is required, enabling the system to operate autonomously. The magnetometer also eliminates the need for heavy and expensive gyroscopes or star trackers, resulting in a lower cost and lighter weight unit. The GPS-MAGNAV system utilizes a single algorithm to process attitude, orbit, and rate simultaneously, requiring less processing power.

The resulting self-contained and fully autonomous navigation system is lightweight, has lower power requirements, and costs less than current navigation systems. Additionally, because of its low weight and cost, this navigation system has the potential to be an enabling technology for micro/nanosatellites.

This technology is part of NASA’s Innovative Partnerships Program, which seeks to transfer technology into and out of NASA to benefit the space program and U.S. industry. NASA invites companies to consider licensing the GPS-MAGNAV System (GSC-14463-1) for commercial applications.

For information and forms related to the technology licensing and partnering process, please visit the Licensing and Partnering page. (Link opens new browser window)

If you are interested in more information or want to pursue transfer of this technology, please contact:

Innovative Partnerships Program
NASA Goddard Space Flight Center
E-mail: magnav@gsfc.nasa.gov