The CHESS CubeSat is a project designed by the École Polytechnique Fédérale de Lausanne (EPFL) Spacecraft Team, supported by the EPFL Space Centre. Students David Sanchez Del Rio and Alessandra Capurro designed a mission concept for a CubeSat constellation around the Earth as for the CHESS mission. Phase A of the mission was largely developed using Valispace’s software.
Model-Based Systems Engineering (MBSE)
The team uses Model-Based Systems Engineering (MBSE) within the Valispace software to design the mission Phase A of CHESS. This method focuses its approach on modelling the system on each of its subdivisions rather than on classical systems engineering documents. The gain in design flexibility is fundamental at early stages of a space mission. It provides more liberty in the choice of the components or the orbit design as well as establishing a set of mission requirements and constraints.
How was Valispace used in this project?
We spoke to David, from the project, who gave us more insight into what it was like to use Valispace for this project.
Our project supervisor, who is working with the EPFL Space Centre told us that using Valispace for our CubeSat mission would be the best choice: it is a complete software and easier to use than others we have seen or tested.
The mission is decomposed into the following high-level categories, as shown below:
Taking a systems engineering approach, setting requirements was the first step in the project. An example is shown of the CubeSat’s operational requirements modelled in Valispace.
According to the report*, it was incredibly useful to see the connections between the project requirements and always be updated on their status, as well as how they’ve changed over time.
The teams found the Modes feature to be very useful, allowing them to simulate different configurations of the CubeSat without extensive calculations. Some components of the CubeSat can be turned off, others remain on, and you can get a broad sense of the CuebSat’s performance in different scenarios.
According to David, traditional systems engineering often requires you to have deeply thought about your budgets, without the adequate information, before you start designing and modelling. This often leads to overestimations of budgets, which wastes a lot of time and money. However, not doing this risks that components won’t be suitable for a function, and thus many changes would need to be made over the product life cycle.
Within Valispace, budgets can be easily generated and changed, also changing the necessary values assigned to components within the project.
The budgets were really nice. Once you get the opportunity to understand how they work, it’s really nice to be able to produce them almost in series. Moreover, they are more flexible to changes in the parameters, which is coherent and helps the system engineering work and the product’s design.
We were able to produce several power and mass budgets. In addition, the MATLAB toolbox was very helpful for all the simulations we did. We highly appreciated the fact that you could directly link a MATLAB code with the results in ValiSpace (and therefore, change the budgets or the requirements according to the code’s outputs for example).
The work of a system engineer is at the boundary between engineering and management. It was highly interesting to be able to follow each subsystem’s progresses and be able to debate on new system design ideas or concepts. This progress within the ambitious CHESS mission has taught us the basics of system engineering as well as the model based system engineering methodology and why this tool is progressively being used worldwide for complex systems design.
As the early design stages of the CHESS CubeSat have been completed, the team is now focussed on getting and testing the necessary components to build the system. Hopefully, within the next couple of years, the CubeSat will be launched.
We wish the EPFL team the best of luck!
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