June 19, 2014 the first Ukrainian nanosatellite PolyITAN-1 was launched in Earth orbit. It was created by scientists, engineers and students FHPE, FRE, FE, ESITS under the guidance of Head of laboratory of nanosatellite technology FHPE, Senior Reshercher, Ph.D. Boris Mikhailovich Rassamakin. Our correspondent met with him.
- So June 19, the satellite was launched into the orbit. What happened next?
- Already on June 20 we received information from radio amateurs in Japan, Russia, Brazil that the satellite operates and transmits information. Transmission is in the Amateur Radioradio band at a frequency of 437 MHz, and amateur radio operators from around the world can receive the signals of our satellite as it flew over the territory of their country. According to international agreements, we have provided radio amateurs with the program, through which they can process the signals from the satellites - the so-called signal code and data telemetry.
- Tell us about the design PolyITAN-1.
- Nanosatellite is a cube with sides of 10 cm. Solar panels were placed on the five faces with a total capacity of 1.3 W, the antenna - on the sixth. Mass of the satellite is about 1 kg. The structure of the satellite includes three standard boards PC104 with electronic components of subsystems, typical for satellite of this class, namely, power subsystem, the processing data subsystem, transceiver subsystem, a navigation subsystem, orientation and stabilization subsystem.
Power subsystem includes: solar panels - the primary source of power; battery - an additional source of power; electronic control board of power supply subsystem - is designed to control and monitor the energy state of the batteries and provide with power various subsystems onboard complex.
The structure of the data processing subsystem includes a central on-board computer, which performs the following functions: coordination of subsystems performance of the on-board maintenance complex; work with data payload, subsystems navigation and orientation.
The structure of transceiver subsystem (radio) includes receiving and transmitting equipment and antenna-feeder devices.
Navigation subsystem includes: a standard precision receiver of the signals navigation systems GLONASS / GPS - modern global positioning device modern, which provides information about the coordinates of the location of the object in space, the average speed of the object, high-precision timestamp in UTC time scale and UTC (SU); two receiver antenna signal standard precision navigation systems GLONASS / GPS.
Orientation and stabilization control subsystem includes three sensors coordinates of the Sun, designed to determine the position of the sun in a coupled system of coordinates nanosatellite; electromagnets, designed to provide the magnetic orientation nanosatellite phases of flight; magnetometer; three-axis gyroscope.
- Who designed and manufactured all this equipment?
Data processing subsystem was designed and produced by programmers and electronics engineers of FHPE. Sun sensors were developed by FHPE specialists and produced by their FE collegues. The power supply system (connection circuit of solar cells to charge the batteries and power supply module) is a FE development. light transformers are made in the laboratory of semiconductor devices FE. Frame was made by FHPE, photocells - FEL. Radiomodule for 144 MHz (link "Land - board") and 437 MHz (link "board - Land") - FRE and ESITS, antenna system - FRE. Software for all subsystems of the satellite (attitude control system, navigation and satellite data processor module radio and power supply) was developed by experts of the FHPE. Thermophysics and Electrophysics from the departments of nuclear power plants and Engineering Thermophysics (FHPE) and technology of high voltage (FEPEA) conducted a thermal vacuum tests in the simulation of conditions of stay in orbit.
15 bachelor's and 10 master's works were defended on this satellite theme. All were defended perfectly. Two theses on energy systems and data processing are prepared now.
- How the satellite is controlled?
- Ground receiving antenna at 437 MHz, installed on the roof of the building №5 (FHPE), provides a link with the satellite when it is at a distance of 2600 km in a straight line, that is, for example, when flying over Berlin or Samara. In addition to the antennas 144 and 437 MHz, the control center has a transmitting-receiving equipment (transceiver ICOM-910N and rotating device for the antenna), and a computer with software that performs scheduling of reception and transmission of information, its decryption processing and archiving .
Communication with the satellite is performed 4-6 times a day - in the morning 2-3 times, 2-3 times at night. The FRE graduate, post-graduate student of telecommunications ESITS Nazariy Bendasyuk is working at the ground station in the building №5 . There is a logbook, where the results of communications, telemetry data and verification of subsystems are recorded.
- Were there any problems during the launch?
The launch was carried out normally, problems arose later. First of all, it turned out that power supplies capacities are not enough for the equipment operation. In order to conserve energy the sattellite signals were decided to be transmitted at intervals of more than one minute, as in the beginning, but two, and subsequently - 4 minutes. Also the telemetry rate was increased. Due to this, the state of the satellite power supply has improved. In addition, through the imperfection of a terrestrial antenna there were initially unreliable communications with the satellite. This problem was solved thanks to the sponsors help - Fund of Academician V.S.Mihalevich, which provided funds to purchase a new antenna, and the Scientific-production firm "Dion" (Director E.V.Lanevsky), who performed the establishment of the antenna and the communication channel. Now there are no any communication problems.
- Tell us how we can represent the motion of this satellite?
- The satellite moves by the orbit with an apogee of 712 km, perigee of 640 km and an inclination of 98 degrees. The satellite moves at an average speed of approximately 7.6 km / s. One revolution around the globe takes 97.5 minutes, 63 minutes of it by the illuminated portion, and 34 minutes - in the shade. When the satellite is illuminated, solar panels feed equipment and charge the battery, while in the shadow of equipment powered by batteries. As the globe rotates, the apparent path of the satellite on the celestial sphere for a specific geographic point after each revolution moves westward about 23 degrees. The trajectory of the satellite is very rare (about once every six weeks) passes directly over the KPI (ie, in the range of 82-98 degrees relative to the horizon). More often its trajectory is shifted to the east or west. During the day, the satellite makes about 15 revolutions around the Earth. Connection with him, we can install only 4-6 times a day - in most cases it passes over half the night hemisphere of the Earth out of sight for us. But every day we get from radio amateurs around the world telemetry data and position of the satellite.
We have software to calculate its trajectory for a long time to come. So we know where at any given time the satellite exact position and, taking into account the rotation of the Earth, when it will be visible to us.
By the way, Uzhgorod Observatory promised to observe the satellite in telescope and give us the coordinates and the time of his flight over Uzhgorod. Thus, it is possible to visually capture a satellite in orbit.
- What are the problems the control center to encounter now?
- As always, after the launch the satellite began to rotate with an angular velocity of 100-110 degrees per second (one revolution in about 3 seconds). This rotation must be stopped. To do this the satellite is equipped with electromagnets, which are switched on by the special program, interact with the magnetic field of the Earth and inhibit rotation. Today it is the primary task. Indeed, until the satellite rotates around its axis, it is not possible to start a navigation system, the operation of which is planned for the mission. Now a lot of energy is spent on suppression of the rotation, but thanks to the measures to save energy, which I mentioned earlier, we have a positive balance of battery charge (not below 40%).
- How long the satellite will operate?
- Warranty period - 1 year. You can expect 1 year 4 months. The service life is determined by the duration of operation of the electronic equipment and batteries, which are negatively affected by cosmic radiation. In general, the satellite can be about 6-7 years in an orbit - until due to a braking will enter the dense layers of the atmosphere and will burn up. In the meantime, we are starting work on a new, larger and more perfect nanosatellite project QB50.