Roman Wawrzaszek

Analytical Model of Eddy Currents in a Reaction Sphere Actuator

A recently proposed technique to control the satellite attitude using a magnetically levitated sphere requires the development of suitable models of its dynamics. One of the phenomena that can affect motion of the system are eddy currents induced in the stator of the actuator due to time variable magnetic field generated by rotational motion of a permanent magnet rotor. We present an analytical model of the eddy currents for the actuator with eight-pole rotor. The model is derived using a second-order vector potential-based approach, and the solution is obtained in terms of spherical harmonic functions. This model allows us to study rotor rotations with constant angular frequency around an axis arbitrarily oriented with respect to both rotor and stator of the reaction sphere actuator.

Application of Digital Control Techniques for Satellite Medium Power DC-DC Converters

The objective of this paper is to present a work concerning a digital control loop system for satellite medium power DC-DC converters that is done in Space Research Centre. The whole control process of a described power converter bases on a high speed digital signal processing. The paper presents a development of a FPGA digital controller for voltage mode stabilization that was implemented using VHDL. The described controllers are a classical digital PID controller and a bang-bang controller. The used converter for testing is a simple model of 5-20 W, 200 kHz buck power converter. A high resolution digital PWM approach is presented. Additionally a simple and effective solution of filtering of an analog-to-digital converter output is presented.

CHOMIK: a multi-method approach for studying Phobos

CHOMIK is the name of a penetrator constructed for sampling and retrieval of Phobos surface material. It formed an integral part of the Phobos Sample Return Mission. In this paper we present its construction and intended mode of operation, since the concept is still viable for future missions either to Phobos or to other small bodies of similar dimensions. We take Phobos as an example to describe the science case for such an instrument and how it might be utilized to resolve important open issues regarding the origin of the Martian moons. Concerning the latter, we place emphasis on measurement techniques and analysis tools for mapping trace element concentrations in returned sample.

Ultra-Light Planetary Manipulator: Study and Development

The demand for the use of Planetary Manipulators is quite obvious in space exploration and in situ research. It can also be predicted that its role will expand in upcoming decades given the planned intensification of space exploration. This chapter presents the newly developed 3dof Ultra-Light Planetary Manipulator (ULPM) designated for extended servicing of exploration tools (e.g., penetrators, small rovers, etc.), or scientific instruments and sensors in planetary missions, where Mars and Moon are the mostly foreseen destinations. It combines new ideas and earlier achievements, both of which had influence on the concept and would demonstrate the technology. In consequence, a laboratory model device was successively developed. Two leading constraints determined the design: very low mass of the unit and long extension range of deployment of the servicing instruments. For those reasons, the utilization of the tubular boom mechanism was preferred. Integrated Ultra-Light Planetary Manipulator was tested in laboratory conditions in order to prove its operational functionality and performance. Particularly, it was examined what is the safety deployment distance for certain loads with acceptable stability of the flexible system structure. This topic was also one of the most important issues for performed analysis and manipulator’s dynamics simulations.

The prototype of space manipulator WMS LEMUR dedicated to capture tumbling satellites in on-orbit environment

Manipulator mounted on an unmanned chaser satellite could be used for performing orbital capture maneuver in order to repair satellites or remove space debris from orbit. Use of manipulators for such purposes is challenging, since the performed task need to be done autonomously, accurately and with robustness even if possible high disturbances appear e.g. due to contact between the manipulator arm end-effector and the target spacecraft. In this paper the WMS LEMUR manipulator developed by CBK PAN is presented with focus on tests performed in the platform-art© facility in GMV Spain.

Development of an optical system for the SST-1M telescope of the Cherenkov Telescope Array observatory

The prototype of a Davies-Cotton small size telescope (SST-1M) has been designed and developed by a consortium of Polish and Swiss institutions and proposed for the Cherenkov Telescope Array (CTA) observatory. The main purpose of the optical system is to focus the Cherenkov light emitted by extensive air showers in the atmosphere onto the focal plane detectors. The main component of the system is a dish consisting of 18 hexagonal mirrors with a total effective collection area of 6.47 m 2 (including the shadowing and estimated mirror reflectivity). Such a solution was chosen taking into account the analysis of the Cherenkov light propagation and based on optical simulations. The proper curvature and stability of the dish is ensured by the mirror alignment system and the isostatic interface to the telescope structure. Here we present the design of the optical subsystem together with the performance measurements of its components.

Performance of the small size telescope sub-array of the Cherenkov Telescope Array observatory

The southern part of the Cherenkov Telescope Array (CTA) observatory will consist of at least three types of telescopes: large size, medium size and small size telescopes. Massive Monte Carlo simulations have been performed using the European Grid Infrastructure to analyze the performance of this array. We present the results of these simulations for a sub-array of small size telescopes of the Davies-Cotton type. Such a telescope, called SST-1M, is currently being proposed for the CTA observatory by a group of Polish and Swiss institutions. SST-1M will have a mirror of 4m diameter and it will be equipped with a fully digital camera based on silicon photodetectors. We present the analysis of the sub-array sensitivity, angular resolution, and energy resolution to demonstrate the fulfillment of the requirements of the CTA Consortium. To verify the results obtained in numerical simulations a construction of a mini array of five SST-1M telescopes is planned. We also present the performance of such a mini array and discuss the prospects of its scientific program.

DigiCam: fully digital compact camera for SST-1M telescope

The single mirror Small Size Telescopes (SST-1M), being built by a sub-consortium of Polish and Swiss Institutions of the CTA Consortium, will be equipped with a fully digital camera with a compact photodetector plane based on silicon photomultipliers. The internal trigger signal transmission overhead will be kept at low level by introducing a high level of integration. It will be achieved by massively deploying state-of-the-art multi-gigabit transceivers, beginning from the ADC flash converters, through the internal data and trigger signals transmission over backplanes and cables, to the camera’s server 10Gb/s Ethernet links. Such approach will allow fitting the size and weight of the camera exactly to the SST-1M needs, still retaining the flexibility of a fully digital design. Such solution has low power consumption, high reliability and long lifetime. The concept of the camera will be described, along with some construction details and performance results.

The Experimental Results of the Functional Tests of the Mole Penetrator KRET in Different Regolith Analogues

Depending on the specific region, the unmanned exploration of the planetary bodies can be divided into three groups: operations above the surface, operations on the surface and operations under the surface. In this chapter we will focus on the operations under the surface, connected with them requirements, available technology and possible output from such research. In this context we will present mole KRET device as a one of the possible solutions for low power consuming device which can be treated as a sub-surface end-effector of a more complicated robotic system. The experimental results of the functional tests of the mole in a 5 m test-bed system will be provided for different regolith analogue. The detailed investigation of lunar analogue will show how the progress of the mole depends on the compaction ratio of the material.

TwinCube—Preliminary Study of a Tether Experiment for CubeSat Mission

The article covers a preliminary research on a Tethered Satellite System based on a 3U CubeSat pico-satellite standard, which main purpose is to perform two-point diagnostic measurements of electromagnetic emissions in near-Earth plasma. Multi-point measurements play a significant role in understanding energy flows driven by Sun as well as terrestrial activity. Since CubeSats are expected to be low-cost and robust, development of a small and efficient plasma diagnostic tool for hardware-restrained CubeSat platform might be important also for future space cluster missions. We propose a TwinCube mission consisting of two sub-satellites that will be preliminarily bonded with lock-and-release mechanisms. During in-orbit operations the mechanism will be released allowing for unwinding of the non-conductive tether and for separating two sub-satellites for up to 1 km. This action is crucial for the mission success and is considered as one of the important technological aspects of the project. Objectives and justification of the mission are outlined in the article, together with basic mission scenario, simulations confirming feasibility of the idea and discussion on assumptions for the mechanical design.