"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.

Today, Artem Pinchuk, an engineer of the Educational and Research Institute of Institute of Nuclear and Thermal Energy, talks about his work.

- Artem, how and when did you start working at the Igor Sikorsky Kyiv Polytechnic Institute on nanosatellites development?

- My participation in the satellites development began back in Dnipropetrovsk (now Dnipro), where I lived and worked at the Pivdenne Design Bureau. Life turned out in such a way that I moved to Kyiv in 2009, where I at first got a job unrelated to space. However, my passion for space topics made itself felt, and in 2012 I came to the Igor Sikorsky Kyiv Polytechnic Institute. It was then that Boris Rassamakin, the head of the scientific group, was selecting people to develop, manufacture and prepare the university's nanosatellite for the launch. I already had some work experience in the field of mechanics of spacecraft flight in orbit, and that determined my further participation in the Igor Sikorsky Kyiv Polytechnic Institute space programme. And until 2014, when the first nanosatellite was launched, I participated in its navigation system development.

- What tasks did you perform within the preparation for the PolyITAN-HP-30 launch?

- My main task was to check all navigation systems and determine the nanosatellite orientation. An almost fully assembled satellite with a payload was handed over to me to check the functioning of all aspects of the navigation and orientation systems. For example, when testing the navigation system, I went up to the roof of our building, connected my laptop to our satellite, and watched the constellations of navigation satellites flying above us through the GPS receiver of our nanosatellite. I checked the signal reception level on two antennas installed on opposite panels of the satellite. There is another, more complicated way to check the navigation system, but given the launch dates we were told, there was no time to do that.

One of the most important tasks when checking the orientation system is to ensure the stabilization of the satellite's flight. When the satellite is separated from the launch vehicle, no one knows how it will rotate. That is, first we must stop any rotation of it. For this, electromagnetic coils are closed. The rotation of closed coils in the Earth's magnetic field leads to the current induction in them. The current in the coils makes them work as electromagnets. The satellite becomes similar to a compass needle in weightlessness. It turns out that the Earth's magnetic field will try to turn the satellite in a different direction than it is rotating. So, first I get it to its minimum spin and then I stop it. So, the first task is to stop the satellite rotation.

Then, it must be oriented depending on the payload. To do this, I first determine its position in orbit, that is, what its coordinates in space are in relation to the center of the Earth. Knowing these coordinates and time, I can calculate two vectors - the vector of the Earth's magnetic field (there is a mathematical model of the Earth's magnetic field) and the vector of the direction to the Sun based on sidereal time and coordinates. Knowing these two vectors at this point in the orbit, I also measure them using the magnetic field sensors and the direction on the Sun sensors. Being in possession of the calculated and measured values of these vectors, I calculate two angles of rotation. It is necessary that they coincide. Actually, these two angles allow us to understand how the satellite is oriented in space. After that, already controlling the current in the coils or changing the flywheel rotation speed, I turn the satellite as required for its payload - either along the line of its flight, or so that it looks at the Earth with the same payload.

A few words about how testing is done. For example, stabilization. In our laboratory, we have a "cage" stand with coils that simulate the Earth's magnetic field in space (see photo). I hang a nanosatellite on an ordinary fishing line and check whether it really stops in the Earth's magnetic field. I spin it a little, and the satellite should stop much earlier than the fishing line twists. There, I check how the satellite works out the orientation. Now, I use the design of an ordinary theater projector as an imitator of the Sun, but the lamp is chosen according to a spectrum close to the extraterrestrial one. I adjust, as it were, a special orbit to the created parameters of the Sun and check whether the satellite is oriented exactly as we need.

- Do you concern yourself with how "PolyITAN-HP-30" behaves in real orbit during the flight of the satellite?

- Definitely. I would like to note that a number of errors in the orientation system were detected on the first satellite - some points of the orbit were calculated incorrectly, insufficient checks were carried out before sending. Later, we did not make such mistakes and, I hope, in the future, we will get rid of the so-called teething problems in projects.

- Do you turn to colleagues for advice or assistance?

- Of course, I turn to and accept help, and not only from colleagues from the Igor Sikorsky Kyiv Polytechnic Institute. During the work on the satellite, it was necessary to contact companies working in Kyiv and beyond, they helped to solve certain problems. In addition, there is such quite a narrow space community in Ukraine, where I can advise something to someone, or somebody can help me clarify some issue through communication.

- Are your future plans related to the Igor Sikorsky Kyiv Polytechnic Institute space programme?

- I am already working on the following projects. It is planned to launch the satellite with a camera so that, after working out the system orientation control, it is focused on the desired points on the Earth's surface. This is quite a serious task for me, and I have been working on it for almost six months.

Interviewer Volodymyr Shkolnyi

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