MIL-STD-1541A: Electromagnetic Compatibility Requirements for Space Systems

Overview

Airborne equipment and systems installed in satellites and other space vehicles are exposed to severe ESD threats. Based on NASA research, and depending on which part of the vessel and which phase of the flight is concerned (Launching, stages seperation, orbital, galactic trajectory, etc.) several generators are recommended: HV coil, flat plate, and direct capacitor injection:

Considerations

ISO 14302 is the most up-to-date standard for ESD testing in space systems and vehicles.

• Test voltages range from kV up to 300 kV, available energy from nanojoules to hundreds of millijoules.
• Source capacitances vary from nanofarads to hundreds of nanofarads, wih peak discharge currents from 1 Amp to 1 kA.

Setting up for ESD Testing

In order to reproduce the ESD effect in space, different ESD test set-ups are used in space industry. The objectives of the set-ups are to reproduce the ESD effects in space i.e. the blowoff:

1) Simulation of the E-field pulse by a radiated susceptibility test with a pulsed discharge at a level of 10 kV and at a distance of 30 cm from each exposed face of the test sample [3] (see Fig. 1); Fig. 1: MIL-STD-1541A ESD set-up

2) Simulation of the current flowing in the spacecraft structure; this could be done by different set-ups:

• by a direct injection onto the unit structure as specified in the MIL-STD-1541A [3];

• by a magnetic coupling test set-up as specified in the ISO14302 [1] and ECSS-E-ST-20-07C [4] (see Fig. 2).

Download

Mil-STD-461G Draft

Data Presentation

Data shall be presented detailing each discharge point, tip used, voltage applied to the EUT at that point (including magnitude and polarity), type of discharge (air or contact), and resulting operating behavior.

More Details

Ground reference plane: A copper or aluminum sheet of 0.25 mm minimum thickness: other materials may be used but they shall have at least 0.65 mm minimum thickness. The minimum size is 1 m2. The exact size depends on the EUT. It shall project beyond the EUT or coupling plane by at least 0.5 m on all sides. It shall be connected to the protective earth.

Coupling planes: These planes shall be constructed from the same material and thickness as that of the ground reference plane and shall be connected to the ground reference plane via a cable with a 470kΩ resistor located at each end.

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