What is the requirement engineering and why is it a so important element of space projects?
What if things in space broke down as often as our microwave, washing machine or robot on a processing line in a factory?
Not-so-good things would happen, and this is best illustrated with a data example. In 2019, approximately 13 million microwaves were sold in the U.S., requiring replacement every 7-10 years on average, and 10 million washing machines, replaced every 10 years on average. By analogy, in space: one of the world’s industry leaders Satellogic has only sent 21 satellites in its entire history (or as many as), and Maxar has sent 4.
In case of home appliances failure, we lose some money and a lot of comfort. In the case of space products, we lose a huge amount of money, data and time spent on development of the product. –What’s more, non-functioning space objects remain in space (natural decay from high LEO takes over 1000 years) and turn into nothing more than space trash, creating a serious hazard. Seeing the obvious difference in the level of loss, it is worth considering – how to prevent big space problems?
The hardest part is the launch
The most complicated thing for space hardware is the launch itself. Sending anything even into LEO is associated with years of preparation and huge amounts of money – and that’s basically what it is. The second and no less complicated thing is space itself. Weightlessness, vacuum, thermal issues, harmful radiation – conditions definitely different from those on Earth. For example, all equipment sent into space should be capable of operating at temperatures between -100°C to 100°C..
Is space the most challenging environment for which man builds machines? No. There are places on Earth where conditions are even less friendly. For example the ocean floor (the deepest point of the ocean is the Mariana Trench, about 11 kilometers below sea level) is the place where we struggle with pressures that require very advanced engineering solutions. Therefore, what is the most important in space projects is a new, open-minded outlook:on the project itself, on the requirements, on the instrumentation tests, on the software, and even on the way the project is managed. Space challenges every obviousness, and acting „by heart”, regardless of the stage of the project is usually harmful.
Tests are the most important
Statistically, most failures appear during the first year of equipment presence in space. The causes are various: electronic, mechanical, software. About 17% of the causes are failures defined as „unidentified”. Since the space industry is not a place where you can afford to learn from the mistakes, the most important part of any space project are (or at least should be) well-defined requirements and thorough tests.
The requirements (functional, performance, or design) are largely shaped by the conditions in which the device will operate. Space itself dictates a lot of them, and we should also add take into account those defined by the nature of the payload itself. So it is not difficult to imagine a list of requirements for a satellite that is several pages long – and that is, among other things: and it’s not a bad sign – it is a sign of a well-recognized environment and clearly defined requirements. Fortunately, we are not alone – we can rely upon external reviewers, who will regularly review and redefine the predefined requirements. Because of this we can be certain, that nothing has been overlooked.
Just listing requirements is not the key to achieve to goal. They have to be constantly verified – during tests, checks, trials, and inspections. Such „training” not only allows you to note errors and learn as the project progresses – but it also provides a sense of order, eliminates many fears, and allows for comprehensive risk management and assessment. Testing is almost the most important part during any space project. No matter how many times we test a given element – there will always be another test to conduct. No matter how many scenarios we consider, something may happen that we weren’t able to predict. The universe still knows how to surprise us.