Satellites And The Harsh Environment Of Space

By John Oncea, Editor

Satellites face harsh conditions, requiring specialized passive and active components. Radiation, temperature extremes, and debris pose risks. Robust design and monitoring are crucial.

Satellites are like delicate instruments in a harsh environment, where anything from atmospheric drag in low Earth orbit to a solar flare can potentially cause major malfunctions. As if that isn’t scary enough, the growing problem of space junk poses a significant threat, as even a small impact can cause catastrophic damage.

“Assuming a satellite survives the launch and calls home without any troubles, it faces a constant battle for survival out in the harshness of space,” writes Data Center Dynamics. “Even Earth satellites in low orbits can see temperature swings of minus 58°F to 122°F every 90 minutes, which can have a big effect on the equipment onboard, as can the lack of air.”

Satellites must be designed with all that in mind, as well as high levels of radiation in space that can damage electronics, software errors that can lead to unexpected behavior, and the hundreds of individual components – passive and active – within a satellite that can fail over time, impacting its functionality.

Of course, when a satellite fails, so too does communications. And if communications fail, so too does GPS, weather forecasting, and broadband and 5G connectivity.

“Satellites are reliable in the sense that they get strapped into a rocket and blasted into space through several Gs of acceleration and a ton of heat noise and vibration, and then operate in a vacuum with significant temperature shifts as they go from sunlight into the shadow back into sunlight, and radiation,” says Dr. Brian Weeden, director of program planning, Secure World Foundation. “In that sense, they are pretty durable.”

Here, we look at what is being done to keep passive and active components – of which the typical communications satellite has in the thousands – safe from the harsh environment of space.

Satellite Anomalies Take Their Toll

Satellite anomalies, according to New Space Economy, are satellite malfunctions or irregularities caused by technical glitches, environmental factors, and human error. They can wreak havoc on a satellite and even result in catastrophic failure. Common types of satellite anomalies:

• Single Event Upsets (SEUs): These are caused by high-energy particles, such as cosmic rays or solar flares, interacting with the satellite’s electronic components. SEUs can cause temporary or permanent damage to the satellite’s systems.
• Thermal Anomalies: These occur when the satellite’s thermal control system fails to maintain the proper temperature for its components. This can result in overheating or freezing of the satellite’s systems, leading to malfunctions or failures.
• Electromagnetic Interference (EMI): This occurs when the satellite’s electronic systems are disrupted by external electromagnetic fields. EMI can cause temporary malfunctions or permanent damage to the satellite’s systems.
• Software Anomalies: These occur when there are errors or bugs in the satellite’s software, leading to malfunctions in its operation.
• Mechanical Anomalies: These occur when there are mechanical failures in the satellite’s systems, such as problems with its solar panels or antennas.

“The effects of satellite anomalies can range from minor malfunctions to complete failure of the satellite,” New Space Economy writes. “In some cases, the satellite may be able to recover from the anomaly and continue operating normally. In other cases, the anomaly may cause permanent damage to the satellite’s systems, rendering it inoperable. The effects of satellite anomalies can have significant impacts on the satellite’s mission, as well as on the people and organizations that rely on the satellite for communication, navigation, or other purposes.”

From a financial perspective, a satellite anomaly can affect not only the satellite operation, but any end user relying on the services provided by the satellite. This includes the cost of repair and replacement, loss of revenue, economic losses for the end users, and indirect economic impacts such as increased prices for satellite-based services.

Keeping Satellites Safe From Anomalies

Satellite anomalies pose significant risks to space operations and can lead to data loss, service disruptions, and even complete mission failure. To address these challenges, various strategies have been developed for preventing and mitigating satellite anomalies.

The American Institute of Aeronautics and Astronautics (AIAA) writes preventing satellite anomalies begins at the design and manufacturing stage, starting with the implementation of safety by design principles and incorporating safety features and best practices into the initial design criteria. Additional design and manufacturing considerations include rigorous testing of satellite technologies before launch, the selection of spacecraft designs with appropriate passivation capabilities to prevent internal breakups, and ensuring satellites have sufficient radar cross-section or optical visual magnitude for tracking.

Once in orbit, active management is crucial, adds The European Space Agency (ESA). Items on this list include ensuring satellites above 250 miles are capable of actively modifying and managing their orbits, practicing collision avoidance by maneuvering satellites away from potential collisions, and implementing disposal plans at end-of-life, including atmospheric reentry or reorbiting to safe altitudes.

And, according to The Satellite Industry Association (SIA), continuous monitoring and effective communication are essential. Operators need to monitor operational spacecraft health and status to detect anomalies that may prevent successful disposal and establish 24/7/365 points of contact for deconflicting possible conjunctions. In addition, space situational awareness information including health status and orbital elements needs to be shared with other operators and tracking authorities.

When anomalies occur, a quick and effective response is critical. Mission rules to require disposal before mission-ending failures occur should be developed and security protocols to prevent unauthorized control of spacecraft implemented.

The Space Environment Customized Risk Estimation for Satellites (SECURES) system combines space environment models with spacecraft charging models to provide tailored risk assessments. This approach allows for:

• Customized alerts based on individual satellite materials and designs.
• Routine estimation of satellite anomaly risks using predictive models.
• Improved decision-making for critical operations based on space weather forecasts.

By implementing these prevention and mitigation strategies, satellite operators can significantly reduce the risk of anomalies and improve the overall reliability and longevity of their space-based systems.

Digging Deeper: Protecting Passive And Active Components

Passive components make up over 80% of the electrical parts in spacecraft, making their reliability crucial. They also have several unique characteristics and requirements due to the harsh space environment and mission-critical nature of their applications. These include, according to TT Electronics:

• Radiation Tolerance: Passive components should be designed to be resistant to Total Ionizing Dose (TID) effects, which can degrade performance over time with special attention given to thin film components like resistor networks, which may be more susceptible to radiation damage.
• Reliability and Performance: Satellite applications demand extremely high reliability and should undergo rigorous qualification and screening processes to ensure they can operate in space conditions.
• Environmental Resilience: These components must withstand extreme space conditions and must be designed to operate across wide temperature ranges encountered in space. Vacuum-compatible materials and construction techniques should be used and components must be able to endure launch vibrations and shock.
• Size and Weight Optimization: Given the premium on space and weight in satellites there is a focus on miniaturization and mass reduction of passive components. As such, surface mount technologies are often preferred to save space.
• Specialized Grades and Standards: The space industry has developed unique component classifications including traditional space-grade components with full radiation hardening and qualification and new space component grades that balance performance and cost for certain missions. Some manufacturers offer modified commercial off-the-shelf (COTS) parts for space use.
• Advanced Materials and Designs: Passive components often incorporate innovative technologies such as the use of materials like Tantalum Nitride in thin film resistors for improved radiation tolerance or specialized designs like radiation-hardened backplanes to protect more sensitive components.

Similarly, active components used in satellites have several unique characteristics of their own that set them apart from those used in terrestrial applications. One of the most critical aspects of active components is their ability to withstand the harsh radiation environment of space.

Like passive components, active components are designed to be resistant to TID effects, which can degrade performance over time. They must also be able to handle Single Event Effects (SEEs) caused by high-energy particles. Because of this, special manufacturing processes and materials – such as Silicon-on-Insulator (SOI) technology – are often employed to enhance radiation tolerance.

The need for high reliability and performance means active components must meet stringent reliability standards. To ensure that this happens, they undergo extensive qualification and screening processes to ensure long-term operation in space.

These components are engineered for extended operational lifetimes, often spanning many years in orbit. High-performance characteristics are crucial, as repair or replacement is typically not possible once deployed.

Given the limited power available on satellites, active components prioritize power efficiency. Low-power consumption designs are essential to maximize the satellite's operational capabilities while high-efficiency power amplifiers are used to minimize heat generation and power usage.

Space presents unique thermal challenges, so much so that active components must be designed to operate across extreme temperature ranges encountered in space. Thermal management solutions are often integrated into component packages to ensure stable operation.

With the premium on space and weight in satellites, there is a strong focus on miniaturization and integration of active components. Multi-function integrated circuits (ICs) are often used to reduce size and weight. In addition, redundancy is built into many components to ensure continued operation in case of partial failure. Some components include self-healing or self-reconfiguration capabilities to adapt to space-induced degradation.

Finally, innovative materials are used in the construction of these components, including Gallium Nitride (GaN), which is increasingly used for high-power, high-frequency applications due to its excellent performance and radiation tolerance. Advanced packaging materials are employed to protect against the vacuum and thermal cycling of space.

Incorporating these strategies and techniques helps ensure the reliability and performance of the passive and active components that make up a satellite, thereby increasing the chances of successful space missions while also adapting to the evolving needs of the modern space industry.