NASA is renowned around the world for its ability to carry out successful space missions. From the moon landings in the 1960s to the most recent missions to Mars, NASA has made significant advances in space exploration. But what is the main success factor behind NASA’s space projects? The answer is systems engineering, the process the space agency uses to design, develop, and operate spacecraft and life support systems in the harsh environments of space. In this article, we will explore NASA’s space systems engineering process in detail, with a focus on mission analysis and design, project decomposition into subsystems, verification, and validation.
Mission analysis and design
The mission analysis and design process begins with defining the project’s objectives and requirements. Systems engineers work with scientists, mission analysts, and other experts to determine mission goals, duration, orbit, payload, and other relevant details. During this process, a thorough evaluation of available technologies is conducted, and budget and scheduling constraints are taken into account.
From this definition, a mission concept is developed that describes the mission architecture, including the components and subsystems required to accomplish the mission. The mission concept also includes risk analysis and identification of potential mitigations. The conceptual design phase is completed with the selection of the most appropriate design approach for the mission, which includes an assessment of technical feasibility, resource availability, and the time required to complete the project.
Breaking down the project into subsystems
Once the mission concept has been defined and the appropriate design approach has been selected, the next step is the decomposition of the project into subsystems. This involves identifying the individual subsystems and components required to carry out the mission, as well as defining the specific requirements for each subsystem.
Typical subsystems of a spacecraft include the structure, propulsion systems, power systems, communication systems, navigation systems, attitude control systems, and payload systems. Each of these subsystems is designed and developed by a team of engineers specialized in the corresponding area.
Subsystem decomposition is a critical part of the space systems engineering process, as it ensures effective integration of all spacecraft components and compatibility of individual subsystems. Each subsystem must be designed to meet specific mission requirements and must integrate safely and effectively with the other subsystems.
Examples of requirements for mission subsystems are as follows:
- The onboard computer subsystem must be able to run spacecraft software efficiently and reliably, and have the processing power to handle mission payloads.
- The power subsystem must be capable of generating and storing sufficient power for the mission, and have redundant systems in case of failure.
- The communications subsystem must meet data transmission requirements to send payload information and receive commands from the ground station.
These requirements are not opinions, but must be expressed in quantitative terms or adhere to standards. In addition, it is important to consider the cost and mass of each subsystem to ensure that they fit within the mission limits and requirements.
Verification and Validation
Verification and validation are critical processes in space systems engineering, ensuring that the spacecraft and its subsystems operate effectively and reliably. Verification is the process of evaluating and confirming that each component and subsystem meets its specific requirements, while validation is the process of evaluating and confirming that the system as a whole meets the mission objectives.
Verification and validation are conducted throughout the entire spacecraft development process, from conceptual design through integration and final test. Mission requirements and individual subsystem requirements are used as a basis for developing verification and validation procedures.
During the verification phase, engineers test and evaluate each component and subsystem to ensure they meet their specific requirements. This may involve ground and space testing, software simulations, and environmental testing under conditions similar to those that will be experienced in space.
The validation phase involves integrating all subsystems into a complete system and conducting tests to evaluate the performance of the system as a whole. These tests may include full mission simulations, ground tests, and space tests.
Once the verification and validation phase is complete, the final integration of the subsystems and components into the complete spacecraft takes place. During this phase, a series of additional tests and verifications are performed to ensure that the spacecraft is ready for launch.
The key to success
The space systems engineering process is a rigorous and complex process that involves detailed planning, effective risk management, and careful integration of subsystems and components. From defining mission objectives and requirements, to breaking down the project into subsystems, to verification and validation, each step in the process is critical to the success of the project.
NASA has developed a detailed process for designing and building space systems that has been used to develop some of the most iconic missions in history, including the Apollo program and the Hubble Space Telescope. This process relies on collaboration and teamwork among scientists, engineers, and other experts, and focuses on the careful selection of components and subsystems to ensure reliability and performance.
As technology and understanding of space systems continue to evolve, new challenges are likely to emerge in the space systems engineering process. The ability to address these challenges and adapt the process as technology advances will be key to the continued success of space systems and to exploration and discovery in space.
by Carlos Duarte