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The Satellite Industry has brought exciting developments to the military, commercial space and consumer markets that have drastically changed the way we communicate. Over the course of just a few decades there have been significant advances that are now indispensable to modern life. While the potential for new satellites is on the rise, there is a perception that they are prone to risk with a high probability of failure.
In a space mission, a risk is a potential failure that can take place during the design, build, transportation, launch or operation of a spacecraft on orbit. During the period up until launch a failure can result in cost overruns, schedule delays and potentially the loss of a critical function of the spacecraft.
During and after launch, a failure can result in the partial or complete loss of the spacecraft or a function of the spacecraft. Depending on the severity, this can lead to a total loss of mission or a reduction in the performance or lifetime of the satellite. To avoid flaws and problems that could never be fixed once in orbit, it is critical to ensure that even the smallest part is manufactured properly to do its job—in space, you do not get a second chance.
Quality assurance is indispensable and complementary to security and reliability. More precisely, quality assurance ensures that a number of objectives and tasks relating to the requirements of the space project become facts.
Quality management and assurance is key to consistently produce space missions that are to the satisfaction of the stakeholders. Its importance increases as the complexity, cost and risk of space projects increase. The effects of a problem in a satellite, launcher or ground support equipment can be devastating in terms of cost, time, public or private property and even human life. It is here where quality management and assurance contributes critically to the success of the mission.
In the end, a chain always breaks at its weakest link; a single nut or bolt, a manufacturing step is forgotten, a material of inferior strength can render a satellite useless in orbit or cause a catastrophic explosion of a launcher. Quality management and assurance are there to ensure that each key method, process, part and material is adequate. Quality management and assurance are there to ensure that changes along the way do not compromise the results. Quality management and assurance are there to provide evidence that things have actually been performed with the desired quality.
Quality management and assurance is all about making sure that the team building a satellite or launcher does the work as it should be done, that the correct materials are being used and the right steps are followed. Workmanship and process standards need to be defined for all activities and products and, in addition, checks need to be performed to confirm that these standards are respected by the team. The same for materials; suitable materials have to be identified and checks need to be performed to confirm that these are indeed the materials used.
Quality management and assurance is also involved in handling the inevitable exceptions to the rules. What shall we do when the work cannot be performed following the intended method and so an alternative one has to be introduced? Or what shall we do if a material we wanted to use is not available anymore or does not work as expected and we need to choose a different one? Any problem or deviation needs to be thought through, otherwise the whole spacecraft may fail. This could mean a large financial loss or even danger to life.
Quality management and assurance has yet another aspect to it. It makes sure that evidence of the quality of the work done, the methods and the materials used is collected and available for inspection. This is very important to reassure decision makers, government officials and users in general that the satellite or rocket manufactured can be successfully launched and will bring the expected return on the investment made.
On one hand, quality management focuses on the general system and processes across projects. On the other, quality assurance focuses on the set of measures to gain confidence on the achievement of the quality of the product.
The main elements of a quality assurance programme are as follows.
Quality of the pre-project studies and definition
This concept phase deals with coming up with the concept for the system. The design begins with understanding the need behind the design, understanding the set objectives and coming up with our expectations of the final product or prototype.
During the analysis phases, quality assurance consists of:
—verifying the conformity of the design documentation (plans and specifications) with the requirements of the programme;
—verifying the conformity of the definition with general quality rules and the particular requirements of the project;
—ensuring that the requirements of reliability, security and quality are taken into account.
The team would have to list down the requirements of the system and various subsystems. When doing so, an example of QA being followed in the requirement writing process would be to have all of the system’s requirements documented comprehensively. ID’s should be systematically assigned to these requirements so as to be able to trace the origin of a particular requirement, as well the entity on which it is being placed. The subsystems tasked with ensuring a given requirement is met also need to be explicitly defined in the requirement list in addition to having a precise definition of the requirement itself.
Design quality
At the design level, conformity of all designs, tests and detailed specifications to the quality rules and requirements of the projects must be verified. At the model testing level, conformity of the models to the design, conformity of the test conditions to the project requirements, the quality of the results and the standards must be verified.
The spirit of QA is to be imbibed in the entire process of satellite design – starting from the selection of payload to the final retirement phase.
Development phase
The quality of a development programme lies in the realisation of mock-ups and models (development mock-ups, mechanical models, thermal models, identifications models, qualifications models and flying models). Tests demonstrate feasibility, provide inputs for optimisation of structures and mass breakdown, mechanical behaviour, thermal behaviour and adequacy of the hardware for the constraints which will be encountered.
Supply quality
Foreign acquisitions and supply chain globalization make it increasingly hard to find reliable suppliers. All components and subcomponents must meet design and life expectancy requirements. Without proper control of the supply chain, products will fail.
The quality of supplies relies on:
—definition of a supply specification that conforms to the reliability requirements and technical performance;
—definition of the qualification and acceptance conditions;
—the choice of components and materials;
—appraisal of defective components and materials;
—definition of acceptance procedures for batches of components.
Quality of manufacture
According to the Department of Defense (DoD), Satellite Manufacturing is a subset of the National Security Space Sector. The sector includes also includes launch services, ground systems, satellite components and subsystems, networks, engineering services, payloads, propulsion and electronics. This is a highly specialized niche market that requires strict oversight and compliance to industry standards.
Manufacturing quality depends on:
—definition of an industrial document that conforms to the quality rules and the requirements of the project;
—monitoring of the manufacturing, assembly, commissioning and repair procedures;
—execution of the quality control plan during manufacture.
Quality of testing
There are many challenges to space. Those can be listed as vacuum, high temperature changes regarding nonconductive thermal feature of vacuum typically between −150 and 150°C, outgassing or material sublimation which can create contamination for payloads especially on lens of cameras, ionizing or cosmic radiation (beta, gamma, and X-rays), solar radiation, atomic oxygen oxidation or erosion due to atmospheric effect of low earth orbiting.
Before being sent into orbit onboard a launcher, satellites undergo extensive testing. Rigorous environmental stress are designed to prove (1) that the satellite can survive the extreme acoustic and vibration environment of launch, (2) that it can sustain the explosive shock associated with separation from the launch vehicle, and (3) that once on orbit, its electronic subsystems can operate successfully in the extreme temperature and radiation environments of space.
To this end, they are placed in a vacuum, heated and cooled. We need to expose satellites to the type of conditions in which they will operate later on. As there is no vacuum on earth in contrast to space, they need to be tested in a vacuum chamber.
During vibration testing, the satellite is placed on a large shaker table and shaken for several minutes at frequencies expected during launch. For acoustic testing, the satellite is placed in a large chamber, then exposed to high-intensity sound waves that simulate the acoustic environment of launch. Shock testing involves exploding the ordnance that’s used on orbit to release the mechanical pins that hold deployable devices in their stowed position.
Verifying that spaceflight systems are electromagnetically compatible is one of the necessary precautions to ensure a successful mission. Spacecraft equipment is considered by National Aeronautics and Space Administration (NASA) to fall under the military industry (GSFC-STD-7000A, 2013) (MILSTD-461G, 2015).
As a general rule, the quality of testing is based on:
—optimum definition of the test programme;
—a test procedure which conforms to the objective (qualification, acceptance or development testing) and is compatible with the requirements of the project (such as constraints encountered in the course of the mission and the duration of the mission);
—the quality, reliability and security of the test methods;
—the quality of the measuring equipment (ensured by periodic checking and suitable conditions of use);
—the quality of performance of the test;
—utilisation of the results.
Control of the configuration
The quality of the whole project depends on thorough knowledge of the system at a given time and hence on subsequent control of the configuration. The organisation of the system, partitioning into assemblies, sub-assemblies, units, components and so on, the definition of basic documents, nomenclature, continuous updating, the availability and dissemination of documentation and information are the important factors for the quality of the configuration and its control.
Non-conformity, failures, exemptions
All recorded non-conformities and failures must be dealt with through a procedure which includes analyses, expert appraisal, statistical evaluation, repairs, exemptions and modifications. This programme is particularly intended to identify the origin of the difficulty, the responsibility and the solution to be used to obtain conformity of the failed element to the reference models (this relates to the specification of the identification model, acceptance and qualification) and to avoid the occurrence of a further deviation in the subsequent part of the project.
Storage, packaging, transport and handling
Storage, packaging, handling and transport conditions are the subject of a set of rules specified with the intention of maintaining the quality of the hardware regardless of the level of integration. These rules contain a number of precautions which are taken so that the hardware is not weakened by constraints for which it is not designed and these must be considered in connection with the equipment used for packaging, handling and transport. Application of these principles determines the validity of operations associated with the reliability and security of space programmes.
An effective quality management solution provides real-time access to quality and manufacturing data for a synced view of the enterprise, ensuring operational excellence throughout the product lifecycle. Visibility into costs allows for greater control of internal processes, as well as supply chain efforts.
Complete traceability of every part in the manufacturing process ensures all components and material meet quality standards. Effective quality management software provides objective evidence of compliance to DoD requirements for counterfeit parts avoidance, mitigation and disposition, and helps satellite manufacturers effectively control their supply chains.
The ability to provide extensive detailed inspection reports including photographic attachments and objective evidence can greatly facilitate problem resolution in case of a failure or problem that may arise after a satellite has been deployed.
References and Resources also include:
https://www.esa.int/Enabling_Support/Space_Engineering_Technology/Quality_Management_and_Assurance
