Expert Tips for Selecting Components in Space Applications

The harsh environments of space make selecting electronic components for satellites and spacecraft challenging. The demands placed on electronic components are unparalleled: from extreme temperature fluctuations to radiation exposure and vacuum conditions, the harsh environment of space presents unique challenges that must be carefully navigated when selecting components for space applications. Here are some of the most important considerations:

1. Radiation Hardness: One of the foremost considerations in space applications is the ability of electronic components to withstand the damaging effects of ionizing radiation. Components exposed to space radiation may experience degradation in performance or even outright failure if not adequately hardened. Radiation can cause a host of issues such as single event upsets, latch-ups, gate ruptures, and burnouts, which can lead to software issues, memory corruption, short circuits, and more. Radiation-hardened components designed to withstand radiation offer increased resilience against radiation-induced effects, making them indispensable for space missions.

2. Temperature Extremes: Spacecraft electronic components can experience extreme temperature changes. For example, in low Earth orbit, a spacecraft could experience a temperature gradient anywhere between -250°C (-418°F) in the shade to 120°C (248°F) in direct sunlight. The vacuum of space means that traditional convective cooling doesn’t apply, so engineers turn to other techniques to remove heat to ensure component performance and longevity under extreme thermal conditions. Choosing parts that have broad temperature compatibility helps mitigate this issue.

3. Vacuum Compatibility: The vacuum environment of space presents unique challenges for electronic components, including outgassing and arcing. Electrolytic capacitors pose a novel risk in space as some can expand in a vacuum and fail, or their electrolyte can boil off. High-voltage systems and components require careful consideration as the insulating properties of air are not available to prevent dielectric breakdown.

Outgassing refers to the release of trapped gases or volatile substances from materials when subjected to a vacuum or low-pressure environment. Outgassing can contaminate sensitive components such as mission-critical experiments and surfaces such as optical components. Glues, epoxies, conformal coatings, thermal pastes, wire cladding, and tapes must be carefully selected and tested for vacuum compatibility to mitigate the risk of contamination.

4. Vibration and Mechanical Shock: Launch and deployment mechanisms subject electronic components to significant mechanical stresses, including vibration and shock. In high G environments, heavy components can rip from PCBs, and BGA packages' electrical connections can fail. Crystal oscillators can be impacted at specific vibration frequencies, causing their output frequency to drift, creating hard-to-diagnose intermittent errors. Electronic components must be ruggedized to withstand these forces. Shock and vibration-resistant designs and mitigations, as well as comprehensive testing protocols, are essential to ensure component robustness in the face of mechanical challenges.

5. Power Efficiency: Power efficiency is paramount in space applications, where energy resources can be limited to what can be generated by solar power, and every watt counts. Low-power components and efficient power management systems help minimize energy consumption and extend mission duration. Selecting components with optimal power characteristics is crucial to maximizing the efficiency and longevity of space missions.

6. Reliability and Redundancy: Reliability is non-negotiable in space applications, where component failure can have catastrophic consequences. Redundancy strategies, including triple redundant components and systems, are employed to mitigate the risk of single-point failures and ensure mission success. Selecting components with proven reliability records and implementing robust redundancy schemes are critical aspects of space system design. Manufacturers often advertise their space heritage for components that have been in orbit for any period, giving engineers more confidence that the part will survive space applications.

7. Helium Compatibility: Helium is used on spacecraft for many purposes, but a common use is to actuate valves as it does not freeze or liquefy when exposed to extremely cold fuels/oxidizers such as liquid hydrogen or oxygen. Helium can pose a problem to MEMS components as its molecules can permeate their crystalline structure and change its characteristics. MEMS oscillators, gyros, and accelerometers can all be impacted by helium, and careful parts selection is required.

8. Authenticity, Traceability, & Regulatory Compliance: Many aerospace companies require certifications, component and assembly level traceability, lot and batch identification, and more to ensure that the components used are not counterfeit, substandard, or of a different design than what has been previously tested. Flight termination systems, the system that will terminate the flight of a rocket through explosive ordnance or thrust termination should it veer off course, are subject to highly rigorous part level traceability to ensure that this critical public safety device works when needed. Many aerospace companies require all parts manufacturers and parts distributors to meet AS9100 and AS9120 regulatory compliance as well.

9. Tin Whiskering: Tin whiskering is the spontaneous growth of microscopic tin protrusions on electronic components, especially those with tin-plated surfaces, which can lead to electrical shorts or reliability issues. This phenomenon can occur on earth, but in the vacuum of space, shorting tin whiskers can initiate a sustained metal vapor arc with a supply voltage as low as 13 Volts. These arcs are capable of carrying hundreds of amps and can be sustained for several seconds. RoHS components and solder are more susceptible to whiskering; often, lead solder is preferred for space applications. Tin whiskering can be mitigated by conformal coating or plating using gold or nickel.

10. Space Qualification and Testing: Some component manufacturers offer space-qualified components that undergo rigorous testing and certification processes to verify their performance and reliability in the space environment. This can reduce the testing burden of a spacecraft manufacturer. Collaborating with suppliers who understand the unique requirements of space applications and offer comprehensive testing and certification support is essential to ensuring the success of space missions.

11. Weight: Weight is a critical factor in electronic component selection for aerospace applications due to the stringent weight limitations imposed by spacecraft design and launch vehicle capacity. The aerospace industry prioritizes lightweight components to minimize the overall mass of spacecraft, which directly impacts mission performance, launch costs, and payload capacity.

In conclusion, selecting components for space applications requires careful consideration of a myriad of factors.

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