The student worked on the thermal control analysis of the CIMER student CubeSat mission, which carries the MIBICO biological payload with cyanobacteria samples. The thermal behaviour of the satellite is an important design aspect of this mission, mainly due to the temperature requirements of the biological payload and the battery system.

As part of the thesis, the student studied the basic principles of the thermal environment in Low Earth Orbit, numerical thermal modelling methods used in space applications, and the creation of geometrical and thermal mathematical models. The student followed up on previous thermal analysis work for the CIMER mission and created an updated model corresponding to a more recent configuration of the satellite. The work was consulted not only with the supervisor, but also with an expert from the European Space Agency. I also positively evaluate that the student used the professional Systema Thermica software, access to which was provided by Airbus Defence and Space.

In the first part of the thesis, the student describes CubeSat missions, the space environment, the main thermal loads acting on a satellite in LEO, and selected biological CubeSat missions. The following chapters describe the CIMER mission, its operational concept, individual subsystems, and requirements relevant to the thermal analysis. The next part of the thesis is focused on the principles of thermal modelling, the selected software tool, and the creation of the geometrical and thermal model of the satellite.

I consider the updated geometrical and thermal model of the CIMER satellite in Systema Thermica as the main contribution of the thesis. The student included the main structural elements of the satellite, material and thermal properties, conductive couplings, and internal dissipations of the individual parts of the system. Based on this model, the student performed simulations of hot and cold boundary cases and selected sensitivity analyses. The results show that a purely passive thermal design is not sufficient to keep the biological payload and batteries within the required temperature ranges, and that active heating of these parts will be necessary in the further development of the mission.

I also positively evaluate that the work provides concrete results that are useful for the next design phase of the CIMER mission. The simulations indicate that overheating does not appear to be the main risk for the analysed configuration - maintaining sufficient temperature of the biological payload and batteries in cold conditions is more critical and this thesis provides a useful basis for further optimization of that.

However, weaker point of the thesis is its formal state. The text contains unresolved or incorrectly linked internal references, and minor typographical issues. The citation apparatus is generally usable and the thesis uses relevant sources, but some references are not correctly linked. This is also related to the fact that the thesis has not been sent for a final check before its final submission.

From the formal point of view, the thesis is logically structured and written in English. The language level is average. The text is generally understandable, but some passages are stylistically less polished and would have benefited from further revision. From the technical point of view, however, the main part of the thesis is usable and provides relevant outputs for the further development of the CIMER mission.

The student worked independently during the thesis and attended consultations prepared. I appreciate his ability to work with a professional simulation tool, create an updated thermal model of the satellite, and evaluate the basic thermal risks of the CIMER mission. In my opinion, the thesis fulfils the assignment in its essential points, although some parts could have been documented more thoroughly. Points proposed by supervisor: 85

The submitted master thesis deals with the thermal control analysis of the CIMER 3U CubeSat mission carrying a biological payload with cyanobacteria samples. The topic is highly relevant, as the analysis is directly connected to an ongoing student satellite project supported within an ESA programme. The thesis provides a clear overview of the mission, its thermal environment and the numerical modelling approach used for small satellite thermal analysis.

The practical part is focused on the creation of an updated geometrical and thermal mathematical model in Systema Thermica. The selected methodology, definition of hot and cold cases, internal dissipations and sensitivity studies are appropriate for the given phase of the project. I positively evaluate that the author works with mission-specific requirements and that the results are directly applicable for the YSpace student team. The work shows that active heating is necessary for the biological payload and batteries, while overheating does not appear to be a critical issue for the analysed configuration.

The thesis is generally well structured and understandable. However, the presentation of results could be more extensive. A larger number of analysed cases, clearer discussion of thermal margins and a more systematic comparison of the results against the requirements presented in the thesis would strengthen the final conclusions. In some subsystem model descriptions, important modelling parameters such as selected thicknesses are not always stated explicitly, although they are relevant for thermal capacity and conductive behaviour. From a formal point of view, the work also contains several non-functional references and links, which negatively affects the final impression.

Despite these shortcomings, the student successfully fulfilled the objectives of the thesis, used adequate engineering methods and demonstrated good understanding of CubeSat thermal analysis. The thesis provides useful input for further thermal design, heater control strategy and future thermal-vacuum testing of the CIMER satellite. I recommend the thesis for defence and evaluate it as B (very good). Topics for thesis defence:

1. 2) What is the difference between thermistor and Pt1000 temperature sensors?
2. 1) In chapter 4.5.2 “Couplings and connections” you mention “surface contacts” values for different surface contact pairs. What is the source for the presented heat transfer coefficient values? Can you describe the influencing parameters on the heat transfer coefficient value?

Points proposed by reviewer: 88