Microcosm Autonomous Navigation System (MANS)

The Microcosm Autonomous Navigation System (MANS) is a pioneering development to increase the utility and decrease the life cycle cost of most space missions. MANS provides in a single, integrated package:

Position and velocity (orbit) Attitude and attitude rate Sun vector (even when the Sun is not in the field of view) Ground look-point Orbit control data

This data is provided at 250-msec intervals in real-time, indefinitely, with no outside data required. Equally important, the system uses a modified version of a standard, high-reliability horizon sensor from Barnes Engineering. Thus the MANS hardware cost is comparable to the cost of Earth sensing alone. Although only a single sensor is required to obtain all of the above information, the following sensors are fully supported and incorporated in the data stream, if they are available:

One or two Dual Cone Scanners Gyros Accelerometers GPS receiver Star trackers

The MANS outputs are independent of GPS or any external system for the life of the mission. Consequently, the spacecraft orbit can be maintained indefinitely without ground intervention. MANS senses the Earth, Sun, and Moon to determine both the orbit and attitude. MANS offers unparalleled flexibility-LEO to GEO, nadir- or inertially-oriented, spinning or three-axis stabilized. This flexibility and the scalable software architecture of the MANS provide a powerful basis for versatile, low-cost spacecraft.

The MANS algorithms were developed by Microcosm and verified in three separate studies by C.S. Draper Laboratories. The Kalman Filter implementation was developed and verified by Dr. Joseph LeMay, an expert in Kalman Filter design for spacecraft navigation. The system was launched successfully on March 13, 1994, as a payload aboard the Air Force TAOS spacecraft. On-orbit experiments to validate both the flight system and the ground simulator occurred during flight-test in 1994.

Along with the hardware and flight software, a complete ground-based simulator was developed for MANS to provide traceability to other missions. The flight experiments will validate the ground-based simulator accuracy assessments. The simulator can then be used to assess the accuracies that will be achieved under other orbits and mission geometries. The result is a powerful and flexible system for which the projected accuracies can be directly traced to on-orbit experimental data. MANS accuracies will, of course, depend upon the number of sensors, configurations, and operating conditions. All of the estimates provided are 3-sigma errors based exclusively on the use of the Barnes Dual Cone Scanner (thus, any additional sensors will further improve accuracies). For most low-Earth orbit conditions, one sensor accuracy is ±500 m in position and ±0.08 deg in attitude. The corresponding two-sensor accuracy is ±100 m in position and ±0.03 deg in attitude. Position accuracy will be maintained continuously once the filter has converged, irrespective of the short-term loss of data due to eclipse or Moon sensing outages that will occur around the time of new Moon.

Autonomous navigation technology provides a wide range of potential applications to low-Earth orbit or GEO missions. The "traditional" uses are to substantially reduce mission life cycle costs by reducing operations cost, increase system reliability by reducing operator-induced errors, and increase survivability by reducing dependence on ground stations. However, a number of new application areas have begun to evolve, including improved resource management, open-loop pointing of payloads, and autonomous orbit and constellation transfer and maintenance. A particularly interesting application is for remote terminals that need spacecraft data, such as tactical satellites, remote sensing satellites, or commercial systems, and which has a widely distributed user base. With autonomous navigation, the ground look-point of on-board sensors can be attached directly to the downlink data, greatly reducing the cost and operational complexity of remote terminals and making the system usable by those who do not have direct access to orbit propagation systems, spacecraft ephemeris data, or attitude transformation data. We believe that autonomous navigation technology has the potential of transforming conventional approaches to space.

Email us at microcosm@smad.com HOME