Heaters Magnetic Emissions Control on Navigation Satellites

Magnetic cleanliness is becoming more demanding for future Precise Satellite Navigation Systems (GALILEO, Moonlight) due the presence of atomic clocks sensitive to magnetic fields, in the range $\mathrm{DC}-\mathrm{mHz}$. Nevertheless, the presence of heaters in the nearby of clocks is also not avoidable since their performance are also dependant to very stable temperature variations (${\lt}3 \mathrm{E}-14 /{ }^{\circ} \mathrm{C}$). This will lead then during the TCS (Thermal Control Subsystem) design from the EMC engineer, to have tight control of the magnetic emissions from the heaters, especially where self-compensated ones cannot be used (i.e. for size or thermal reasons). This paper will give an analysis approach to lead the EMC engineer to prevent any magnetic interference in the early TCS design phase in the frame of satellites embarking atomic clocks.