Jerzy Grygorczuk

Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko

Thermal and mechanical material properties determine comet evolution and even solar system formation because comets are considered remnant volatile-rich planetesimals. Using data from the Multipurpose Sensors for Surface and Sub-Surface Science (MUPUS) instrument package gathered at the Philae landing site Abydos on comet 67P/Churyumov-Gerasimenko, we found the diurnal temperature to vary between 90 and 130 K. The surface emissivity was 0.97, and the local thermal inertia was 85 ± 35 J m−2 K−1s-1/2. The MUPUS thermal probe did not fully penetrate the near-surface layers, suggesting a local resistance of the ground to penetration of >4 megapascals, equivalent to >2 megapascal uniaxial compressive strength. A sintered near-surface microporous dust-ice layer with a porosity of 30 to 65% is consistent with the data.

Experimental demonstration of singularity avoidance with trajectories based on the Bézier curves for free-floating manipulator

Path planning problem for a free-floating space manipulator can be solved in Cartesian space. In such approach, inverse kinematics is solved on the velocity level using the manipulator Jacobian, but dealing with dynamic singularities may be problematic. In this study, we present application of the Bézier curves for path planning. Modifications of curve shape allow avoidance of singularities. The selection of the Bézier curve parameters responsible for its shape is intuitive and simple. The demonstration of the proposed method was performed for a real system using planar air-bearing microgravity simulator. Experimental results are in agreement with the results of the numerical simulations.

Manipulator Mounted on a Satellite versus Manipulator Mounted on UAV Helicopter - Comparative Study

The free-floating satellite performing autonomous rendezvous and docking maneuver (RVD) to the uncontrolled target satellite is a topic of discussion especially in context of the path planning optimization, control algorithm design as well as approach to the testing procedure. In this paper we investigate the possibility of using an unmanned helicopter as a test platform for examination of control algorithms which could be used on the satellitemanipulator system. We are presenting the typical RVD maneuver in which uncontrolled tumbling satellite is captured by manipulator arm. Then, to prove the correct development of the simulation tool as well as the controller of the space robots (6+6 DoF) during RVD maneuver, the comparison of the simulation and testing of the helicopter equipped with manipulator arm (6+2 DoF) is performed. Additionally, design of a special lightweight manipulator applicable to UAV 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.

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.

Space penetrators — Rosetta case study

In the paper a two decades long development of low velocity penetrators and devices derived from them in Space Research Centre is presented. The case study is penetrator developed for the Philae lander on the Rosetta that laid the fundament for further constructions. Two main Rosetta penetrator mechanisms described here are: the insertion mechanism that is based on a electromagnetic hammer and the deployment device that employs a pair of tubular booms. The requirements to be met and constraints imposed on the mechanisms led to a compact solution that, however, have to follow quite a complicated nine-stage scenario to fulfill its goal. The mechanisms developed for Rosetta evolved later into three different lines described shortly in the paper: mole-type penetrators that can go to deep subsurface, sample taking tools that exploit hammering mechanisms and ultralight deployment device.

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.

Photometric modelling of the Martian dust rings

Abstract There are reasons to expect that Mars is surrounded by a region of dust, similar to rings, originating from the bombardment of Phobos and Deimos by meteroids. Using a simple radiative transfer model, we have investigated the angular distribution and the absolute values of the solar radiance scattered by such a dust region, to the purpose of assessing the possibilities and limitations of future photometric searches after the circummartian dust. Our model values of the number density of the dust grains in the space around Mars and of their size distribution have been derived from the results obtained by other authors. The single-scattering albedo of the dust grains has been deduced from the reflectance spectra of Phobos, taken by the spacecraft Phobos 2. Calculations, carried out for a few phenomenological phase functions, have shown that in the visible the radiance scattered by the rings is well within the detectability range of a modern sensible photometer, so that the prospectives for photometric search for the Martian dust rings are optimistic. Furthermore, our results confirm that the dust region could not be observed by the Viking cameras and this supports o our assumptions regarding the optical properties of the circummartian grains.