Spacecraft system failures can have catastrophic consequences for missions, crew, and satellites. To prevent them, aerospace engineers need to apply rigorous methods of design, testing, and operation. In this article, you will learn about some of the key aspects of spacecraft systems engineering that help to ensure reliability, safety, and performance.
One of the most common ways to prevent spacecraft system failures is to design for redundancy. This means having backup components, subsystems, or systems that can take over the function of the primary ones in case of a malfunction. For example, most spacecraft have multiple power sources, such as solar panels, batteries, and fuel cells, that can provide electricity in different scenarios. Redundancy can also be achieved by having different modes of operation, such as low-power or safe mode, that can reduce the demand on the system and preserve its functionality.
The design process should make every effort to design out possible failure modes. That’s not 100% possible, but in many cases failures can be mitigated by good design. Redundancy is a factor, although it doubles the possibility of a failure if the exact same component or system is used. Adaptability is also important; when the Apollo program decided to adopt the lunar orbit rendezvous approach (which had not been initially part of the program and was not favored by some influential members of the program), not only did they end up with a more efficient and lighter spacecraft combination, they also provided a second vehicle which could be used as a lifeboat in the event of a failure seriously degrading the primary spacecraft (see Apollo 13).
The most ways to prevent spacecraft system failures is to design for redundancy. This means having backup components, subsystems, or systems that can take over the function of the primary ones in case of a malfunction.
Indeed, redundant system will help. But checking is important that they are truly redundant. And that access to the system which is now needed can be easily achieved. Important to ackowlwedge is if you have time to understand the failure or if immediate action is required. Example: seperation of launcher interstages etc versus holddown and release of ons solar array wing
Rapid iteration prototyping and testing, look to SpaceX and Tesla industry leaders in performance and Safety in their respective Fields
In the fault management design process, we first try to avoid system failures with reliable components and operational practices. Depending on the program risk posture, we can include redundancy as a mechanism to prevent inability (loss of) functional hazards. Redundancy can come in the form of external redundancy (e.g., block redundancy and cross-strapping) and internal/modular redundancy. When performing redundancy architecting, we must consider impacts to system resources, such as mass, power, thermal, as well as system complexity, as redundancy increases the number of interfaces and therefore system complexity. Finally, we need to consider the impacts of redundancy on Fault Containment Regions.
Another way to prevent spacecraft system failures is to test for robustness. This means exposing the system to various environmental and operational conditions that it might encounter during its mission, such as extreme temperatures, radiation, vibration, and vacuum. Testing for robustness can help to identify and eliminate potential faults, errors, and weaknesses in the system before launch. For example, most spacecraft undergo thermal vacuum testing, where they are placed in a chamber that simulates the space environment and subjected to cycles of heating and cooling.
Testing is the best way to find emergent behaviors in a system, which are unexpected system behaviors due to system complexity. Despite our best efforts during the system design process, the human brain can not fully understand complete system complexity. It’s only when we decompose and abstract behavior in lower layers of the system can we begin to understand how the system works. Once the system is fully integrated with hardware and software, we occasionally find “gremlins” during testing, which are the systems’ emergent behavior. This is the only time we might see it and have the ability to correct prior to system deployment.
In short, there is nothing more important than to test, test and test. Sometimes, tests will be performed that push material to its breaking point, just to ensure that all safety factors are met. One great example are cryogenic pressurized propellant vessels. These will sometimes get pressurized until the tank bursts. This ensures that in real flight conditions, the tank is sufficiently strong. My favorite example is a robustness test Von Braun performed on the Saturn 5 rocket engine - the Rocketdyne F1. To ensure combustion remains stable, he would set off grenades right outside the combustion chamber. This could easily disrupt the combustion process, so if the engine survives this test - it is certainly flight worthy!
Any system in order to keep in good shape it needs maintenance which following the manufacturer recommendation. Test , servicing, functional in order to confirm system is in the level as a new as the manufacturer has determined in maintenance Manuals .
A third way to prevent spacecraft system failures is to monitor for anomalies. This means collecting and analyzing data from the system during its operation, such as telemetry, health, and status information, to detect any signs of degradation, malfunction, or failure. Monitoring for anomalies can help to diagnose and troubleshoot problems, as well as to implement corrective actions, such as reconfiguring, repairing, or replacing components. For example, most spacecraft have onboard computers that can perform self-checks and send alerts to the ground control if something goes wrong.
This goes right along with collecting data. When you have a design, especially on a collabritive mission. You will already have lots of brainstorming minds in the room. And for the sake of humanity, a global collaboration. Everyone needs to have a voice and have it heard. Encourage and uplift people to speak up. Also, with advancements in the AI integration, we can collect the data, process it, and use this tool to create more data that is valuable. The processing power and the programming can and will output good ideas that can be integrated into further discussions of prepared anomalies that can occur. Depending on the mission, you curate this data and integrate it into the plan.
Fault Management encompasses the ability to observe individual system states to a) trend system performance and b) determine when off-nominal conditions are present. A principle of system autonomy dictates the ability to first observe desired system states, otherwise the system/operators have no knowledge of fault conditions are present. In the design process, we assign software-based fault detection functionality to failure modes with short Time-to-Criticality, as the time to detect a fault condition + respond to control the condition is shorter than an operator can act. More advanced fault management concepts employ intelligent health monitoring, which uses ML/AI that allows systems to make decisions without a priori design knowledge.
A fourth way to prevent spacecraft system failures is to learn from experience. This means reviewing and evaluating the performance and outcomes of previous and ongoing missions, as well as incorporating feedback and lessons learned from other experts and stakeholders. Learning from experience can help to improve the design, testing, and operation of future systems, as well as to avoid repeating the same mistakes or overlooking the same risks. For example, most aerospace engineers use databases and reports that document the history and results of spacecraft missions and system failures.
This is such a simple yet powerful strategy. When we have documentation regarding past mistakes and lessons learned on similar missions, why not seize the opportunity to use this precious knowledge to our advantage? This is why the design process must go hand-in-hand with thorough literature review before a path is set in stone for any design.
One of the holy grail’s of spacecraft autonomy is the concept of Intelligent Health Monitoring, which uses ML training data + AI that allows systems to make decisions in the presence of faults without a priori information. Building up ML training data will rely heavily on experience of prior missions to train spacecraft Flight Software on failure signatures. We need large data sets to train software, and the best source is from flight data of previous missions.
A fifth way to prevent spacecraft system failures is to apply best practices. This means following the standards, guidelines, and recommendations that have been established by the aerospace industry and community for spacecraft systems engineering. Applying best practices can help to ensure consistency, quality, and compliance in the system development and management. For example, most aerospace engineers use the Systems Engineering Handbook, which provides a comprehensive and detailed framework for spacecraft systems engineering.
A sixth way to prevent spacecraft system failures is to innovate for improvement. This means seeking new and better ways to design, test, and operate spacecraft systems, as well as to adapt to changing needs and challenges. Innovating for improvement can help to enhance the performance, efficiency, and resilience of the system, as well as to create new opportunities and solutions. For example, some aerospace engineers are developing novel technologies and methods, such as artificial intelligence, additive manufacturing, and modular design, for spacecraft systems engineering.
Don't. Accept that failures will happen when pushing the boundaries of technology. It is cheaper and faster to prototype fast and learn from failures than to design for every contingency. If you fear failure, you will fail to innovate. Instead, fear learning nothing from failure and collect all information possible from each attempt to reach further each time.
Test pilot Chuck Yeager said he did not get involved with rockets because he did not like the way they clapped when one of them worked.