"KP" continues publishing interviews with young scientists of the Igor Sikorsky Kyiv Polytechnic Institute, who developed, manufactured and prepared the PolyITAN-NR-30 nanosatellite for space launch within the scientific body under the leadership of Boris Rassamakin.

Kostiantyn Polovynkin, a thermal control engineer of the heat pipes and nanosatellite technologies laboratory, told the newspaper correspondent about his work today.

- Kostiantyn, how and when did you tie your life to the Igor Sikorsky Kyiv Polytechnic Institute?

- I was born in the city of Severodonetsk, Luhansk Oblast, and lived there until 2014. When the famous stormy events began in the city, I moved to Kyiv with my parents. I managed to complete 9th grade of secondary school in Severodonetsk, and then completed high school in Kyiv. I always liked physics and mathematics at school. Even in high school, I began to realize that there were elements of physics and mathematics in any surrounding process. Apparently, that's when I decided to engage myself in these subjects. Why did I choose the Igor Sikorsky Kyiv Polytechnic Institute? Because I already knew that this institution was the leader of technical education in Ukraine. In addition, I visited the university campus more than once, liked how everything was arranged here, talked to students, and finally came to the conclusion that the Igor Sikorsky Kyiv Polytechnic Institute is the place where I would continue my studies, and that my future was there.

- When did you start working on nanosatellite technologies?

- In 2022, I completed master's studies at the Education and Research Institute of Aerospace Technologies of the Igor Sikorsky Kyiv Polytechnic Institute in the educational program "Computer modeling in engineering thermal physics". I started working on nanosatellite projects in the second year of my undergraduate studies in 2018, and the topic of my master's thesis was "PolyITAN-4-BIO". My primary place of employment after graduating from the Igor Sikorsky Kyiv Polytechnic Institute is the "Kyivinform" enterprise, where I hold the position of chief computer software engineer. I work part-time at the Department of Nuclear Power Engineering in the heat pipes and nanosatellite technologies laboratory. I plan to embark on postgraduate studies this year.

– Tell us more about your participation in the development of "PolyITAN-HP-30".

- I engaged in the task of developing the thermal regime for "PolyITAN-HP-30" about a year ago. It consisted in ensuring the thermal regime of the nanosatellite during the entire period of its stay in Earth orbit. It is known that the surfaces of the satellite during its stay in orbit are subjected to a significant thermal load of varying sign. One side of the nanosatellite, which is oriented towards the Sun, heats up a lot, and the other side, which is turned towards the Earth, cools down to sub zero temperature. Such fluctuations have an extremely negative effect on materials, electronics, and the entire spacecraft. And my main work is the satellite thermal state computer modeling. That is, having certain data, certain materials, and approximate design solutions, we optimize the thermal state in such a way that the required temperature range is maintained inside the apparatus in orbit. We also test subsystems by conducting computer simulations of different scenarios of thermal load on the central computer subsystem cards, orientation and navigation control, power supply, telemetry and high-speed radio channels, nanosatellite body, battery and solar batteries, etc. Let's say, electronics generate a certain amount of heat during active operation, and if it is not rejected or there is too much of it, the temperature inside will rise significantly, and the electronics may fail. The electronic system will most likely have a short period of operation or will fail immediately without thermal stabilization of the nanosatellite equipment electronic components in accordance with the requirements for their temperature range of operation.

- And how does heat exchange occur in outer space?

- heat exchange occurs only due to radiation due to the absence of an atmosphere and, accordingly, convection in space. We use a radiator painted in black, which has a high radiation coefficient to solve the problem of maximum optimization of heat exchange in "PolyITAN-HP-30". My work on this satellite began with the radiator development. First, we chose the format, i.e. what could be the optimal geometry of the radiator. Various design options were tested and computer simulations were conducted for each to determine the most effective one. As a result, we decided in favour of a pyramid-shaped radiator. We came to the conclusion that such a radiator would not heat itself by over-irradiation due to its specific shape, but would give up the maximum amount of heat into outer space.

- Has this choice been backed up with relevant tests?

- Certainly. Before starting the physical tests, the maximum number of studies was carried out precisely with the help of computer simulations. And after we arrived at a certain conclusion, we manufactured this radiator in our laboratory using our own resources, and added an aluminum heat pipe to it (“KP'' talked about this pipe in the last issue - Ed.). The device was assembled, and we conducted its physical tests with simulation of the impact of outer space at the laboratory of thermal vacuum tests of the Igor Sikorsky Kyiv Polytechnic Institute with its unique complex of specialized test benches. For this, we have a heat flow simulator, a thermal vacuum chamber with cryo screens. We always back up theoretical results with physical tests, thereby verifying the results of computer simulations and comparing how effective our choice is.

- What difficulties arise at work, and how do you overcome them?

- We communicate, discuss tasks and upcoming plans in our heat pipes and nanosatellite technologies laboratory (scientific supervisor - Boris Rassamakin) regularly. After that, everyone works out a certain direction for himself and agrees with the supervisor and colleagues. My working mode is combined. As I work on my own computer equipment, I can work from home, and if necessary, I can arrive at the Igor Sikorsky Kyiv Polytechnic Institute. It is definitely not without difficulties in the working process: sometimes my calculation model can be too complicated for my laptop, and I have to simplify and optimize it. Of course, so that it does not affect the final result.

- Do you participate in other projects of the Igor Sikorsky Kyiv Polytechnic Institute Space Program ?

- Yes, now I am working on two more satellites. Nanosatellite "PolyITAN-3-DZZ" is being developed for the study of natural resources of Ukraine. Its main feature is a camera for taking pictures of the Earth surface, which can be used to perform a wide range of tasks. The second nanosatellite, "PolyITAN-4-VIO", is being developed for the purpose of conducting biological research. Its main design feature is a special hermetic biocapsule in which the root substrate of the plant is placed. It will be in studies revealing the degree of the outer space factors (microgravity and radiation) influence on the organic compounds (plants, microorganisms) development.

- At the age of 24, you have graduated from the university and are going to embark on postgraduate studies, you also have considerable achievements in your work. Can you answer briefly what studying at the Igor Sikorsky Kyiv Polytechnic Institute gave you?

- Igor Sikorsky Kyiv Polytechnic Institute taught me how to study. Here I was taught to select from tons of information exactly what is necessary and relevant, and to use it in practice.

- Do you have any hobbies in your spare time?

- There are certain difficulties with free time due to busy work. But I am glad that I can tie my life to the projects I am working on. I am a happy person because I am doing what I like.

Interviewer Volodymyr Shkolnyi