In order to prevent damage to technology used in space environments, it is critical to understand and account for space radiation effects on electronics. For stakeholders in the manufacture, launching, and operation of satellites in particular, a knowledge of how to protect a vehicle from satellite radiation effects is vital.
Radiation Effects in Space
From the high-energy electrons trapped by Earth’s magnetic field in the Van Allen belts, to other forms of space radiation, electronics used in space face many challenges. Some of the issues that radiation can cause are instantaneous, while others are more long-term in nature.
Single-event effects (SEEs) occur when an ionizing particle deposits a charge as it passes through a device and the charge is large enough to adversely affect it. The result of an SEE can be anything from a minor, transient issue to the catastrophic failure of a part or system. This includes issues like single event latchup (SEL), single event burnout (SEB), single event upset (SEU) and others.
Cumulative radiation damage from total ionizing dose (TID) can produce loss of elasticity or embrittlement in polymers. In optics, it can create color centers, which manifests as absorption, and also a condition called luminescence. Issues like changes in how electronics function can occur as well, including how they are activated or deactivated.
Key Considerations for Preventing Satellite Radiation Effects
Fortunately, there are steps stakeholders can take to protect satellites from space radiation effects. For materials and structures, these actions include:
- Avoid leaving polymers directly exposed to space environments. Cover them with multi-layer insulation (MLI), for example.
- Don’t leave “mouseholes” in your spacecraft. Closeout all openings in the chassis to prevent plasma from entering the vehicle.
- Follow good electrical grounding practices. Avoid leaving anything electrically isolated, especially conductors.
To protect optics from space radiation effects, make the front surface lens a sacrificial lens that is radiation hardened, such as one made of fused silica. Allow it to shield the rest of the glass and minimize degradation of the optics.
To minimize space radiation effects on electronics, do the following:
- Design for parametric degradation. In other words, don’t push your design to its limits, but rather allow for voltages to change and leakage to increase, don’t expect large BJT gains, etc.
- Filter voltage references.
- Use wide differential inputs on comparators.
- Use error correction codes (ECC) on memory and then scrub to correct errors so they don’t accumulate.
- In general, minimize voltages. One way to do that is to use a rad tolerant front end to step down voltages and lessen the risk for downstream components.
- Use rad tolerant hardware watchdogs, especially if you have circuits that can’t be reset (which is not advised).
Work with a Radiation Effects Testing Facility
The best practices above will help you select materials and design components and vehicles that are more resilient and better protected from satellite radiation effects. To confirm their resilience, it is critical to collaborate with a radiation effects testing facility.
Experts like ours at Radiation Test Solutions can put materials and components through extensive radiation testing and provide detailed analyses of the results. Our satellite testing process enables designers and manufacturers to move forward with satellite development knowing that the vehicle, when completed, will be ready to face the rigors of space radiation environments.