Protection of the Spectr-R Spacecraft Against ESD Effects Using Satellite-MIEM Computer Code

There are two competing tendencies in spacecraft (SC) design and manufacturing. On the one hand, it is a never-ceasing upgrading of the SC electronics to lower energy consumption and increase its functionality, which in turn makes it more susceptible to electrostatic discharges (ESDs). On the other hand, designers constantly seek to improve electronics protection against ESDs. Spectr-R SC features on-board equipment, which is highly sensitive to possible ESDs. To exclude ESD-related failures, the following protection measures have been taken. Based on the Satellite-MIEM computer code, we developed the lumped-element model of the Spectr-R body currents and cable-affected electronic response. This model made it possible to compute SC body currents initiated by ESDs originating at various structural sites. For various cable harnesses, we measured transformation coefficients converting body currents into the amplitude of the noise voltages appearing in a cable (a patented methodology was used for this purpose). Afterward, these transformation coefficients together with the ESD-induced currents have been fed into the Satellite-MIEM software to compute noise voltages appearing in electronic input circuits, connected via these cables to the satellite exterior surface. Comparing protection efficiency of cables and electronic equipment allowed us to select suitable cable harnesses and the appropriate equipment protection to insure reliable in-flight performance of the space vehicle. From the launch in July 2011 and up to the present time, there were no failures of the Spectr-R electronics, which could be traced to ESDs.