Silicon Sensing said on September 23 that eight DMU41 inertial measurement units returned to normal operation after single-event effects testing with protons at energies from 50 to 200 MeV, while separate total ionizing dose trials exposed the units to as much as 30 kRad(Si). Post-test acceptance procedures found no significant performance drift, providing satellite developers with new data on how the tactical-grade sensor responds to both individual particle strikes and accumulated radiation.
The test program examined two distinct radiation risks facing spacecraft electronics. Total ionizing dose, or TID, measures the cumulative degradation caused by radiation over a mission, while single-event effects, or SEE, are immediate disruptions produced when an energetic particle passes through sensitive electronics.
Eight DMU41 units underwent SEE testing at proton energies of 50, 100, 150 and 200 MeV. At 50 MeV, testers recorded momentary reductions in current consumption while the affected unit continued operating without requiring a restart. A separate event interrupted communications and required a power cycle before normal operation resumed.
Similar recoverable events occurred during testing at 100, 150 and 200 MeV. Some required power cycling, but every unit returned to normal operation. Follow-up acceptance testing found no significant performance drift, and all eight units remained within their specified performance limits.
Reset Architecture Supports Recovery
The results are significant because spacecraft electronics cannot be expected to avoid every particle-induced upset. Mission designers instead assess whether an event can cause permanent damage, leave hardware in an unrecoverable state or be cleared through an autonomous reset or commanded power cycle.
The DMU41 uses a watchdog circuit that continuously monitors its main processor. If the processor locks up, the watchdog can initiate an internal reset. Critical components outside the processor’s direct control—including the communications chip, main voltage regulators and processor power supply—are hardwired to remain active.
That architecture is intended to preserve the functions needed to restore operation after a particle strike. It also allows spacecraft designers to treat occasional resets as manageable operational events, provided that reset behavior, fault detection and recovery procedures are incorporated into the satellite’s avionics and flight software.
For missions using the sensor in a primary attitude-determination or navigation chain, the test results do not eliminate the need for system-level fault protection. Satellite developers may still use redundant sensors, independent power switching and safe-mode logic to prevent a temporary IMU interruption from affecting spacecraft control.
Total Dose Testing Reaches 30 kRad
In the cumulative radiation campaign, DMU41 units were exposed to as much as 30 kRad(Si), three times the 10 kRad benchmark commonly associated with low Earth orbit missions. The manufacturer said the results support use in LEO applications at exposures around 10 kRad and could enable deployment in geostationary orbit when appropriate shielding is added.
Actual radiation exposure depends on orbital altitude, inclination, mission duration, solar activity and spacecraft shielding. Polar and high-inclination spacecraft may encounter increased particle flux, while satellites operating beyond LEO can require additional shielding and more extensive component-level radiation analysis.
The testing was part of a program conducted by Silicon Sensing with the Institute of Science Tokyo at the Wakasa Wan Energy Research Centre in Fukui, Japan. The partnership was announced in April 2024 and was established to assess the DMU41 in radiation environments relevant to commercial spacecraft.
The nine-degree-of-freedom DMU41 combines gyroscopes, accelerometers and magnetometers in a unit measuring approximately 50.5 by 50.5 by 51 millimeters. It weighs less than 180 grams, consumes less than 2 watts and operates across a specified temperature range of minus 40 to 85 degrees Celsius.
Its compact size and power demand are aimed at small satellites that require higher inertial performance without the mass and power consumption of larger fiber-optic gyro systems. The latest report adds detailed recovery behavior to the previously released cumulative-dose results, giving spacecraft integrators more information for radiation analysis, fault-management design and component selection.
