GAMAG

Spacecraft Magnetic Cleanliness Analysis Software

DC-magnetic cleanliness of a spacecraft is required in the following cases:

• Earth and interplanetary science missions carrying magnetometers like Ulysses and Cluster
• missions where the AOCS lifetime or experiment functions are influenced by the magnetic properties of the spacecraft

GAMAG is a new state-of-the-art DC-magnetic modeling tool for spacecraft, based on know-how gained over more than two decades. It calculates, on the basis of given near-field measurements, the field of a satellite outside the measurement distance, at any user-defined location. It analyses the magnetic cleanliness of the satellite and calculates thereupon an optimal compensation-magnet system in order to satisfy the magnetic cleanliness specification of the satellite.

The modeling method implemented is based on the classical postulate:

Any magnetic object can be represented by dipoles

The optimization of the Multiple Dipole Model (MDM) consists in finding individual dipole positions and moments that lead to a best fit of the near-field measurements. Thereupon, the far-field configuration is calculated, in particular at the Cleanliness Specification Point.

In contrast to previous software (MAGNET) the GAMAG software is a completely automatic, and yet flexible, analysis tool. Indeed, no pre-knowledge is required anymore. The classical problems of parameter initiation and boundary constraints are solved automatically. Session times have been reduced from (previously) hours to minutes.

The basic output of GAMAG is:

• the optimal MDM,
• the field (mean, standard deviation) at given specification points,
• the optimal set of compensation magnets for these points.