The Solar Sail Materials (SSM) project – Status of activities

SSM (Solar Sail Materials) is an on-going project for the European Space Agency (ESA) relying on past and recent European solar sail design projects. It aims at developing and testing future technologies suitable for large, operational solar sailcrafts.     

Materials selection for electronic enclosures in space environment considering electromagnetic interference effect

Using low power electronic devices for space applications to reduce the mass and energy consumption has lead to electromagnetic interference (EMI) problem. Electronic enclosures are used to shield electronic devices against EMI. In the past, electromagnetic shielding has been mainly the only criteria considered in electronic enclosure design. However, there are several structural and thermal requirements for selection of shielding materials which should also be taken into account. In this research work, three quantitative materials selection methods, i.e. Digital Logic (DL), Modified Digital Logic (MDL), and Z-transformation, are employed to select the best material from among a list of candidate materials. Composite and metallic electronic enclosures are explored and the best material is selected. Z-transformation method is applicable to both of the considered case studies while DL and MDL can only be used for solving one of them. Z-transformation method ranks aluminum as the first choice among various metallic materials. The wide range of Z-transformation application and its practical results confirm the superiority of Z-transformation method over DL and MDL methods.     

Analysis of nonlinear deformation and stability of reinforced elliptic cylindrical shells under bending with internal pressure

A finite element statement of solving problems on stability of reinforced elliptic cylindrical shells taking into account momentness and nonlinearity of their subcritical stress strain state is presented. The explicit expressions for displacements of noncircular cylindrical shell elements as rigid bodies are determined by integrating the equations obtained by equating the components of linear strains to zero. These expressions were used to construct the form functions for an efficient quadrilateral finite element of natural curvature. An efficient numerical algorithm of nonlinear deformation and stability of shells was developed. The stability of reinforced elliptic cylindrical shells under combined loading by bending moment, transverse boundary force and internal pressure is analyzed. We also examine how the critical loads are affected by the strain nonlinearity and ellipticity of shell deformation at the subcritical stage.     

Improvement of conventional combustion chamber structure in order to enhance GTE ecological indicators

The test results of a conventional combustion chamber with the improved structure are presented. The concentration of toxic substance emissions is reduced as compared with combustion chambers of the similar type.     

Integration and calibration of a multi slit spectropolarimeter

Multi-slit spectropolarimeter is a next-generation spectropolarimeter to obtain vector magnetic field information at high spatial, spectral, and temporal resolution for studying the magnetic structures on the Sun. Once developed, it can be used as ground based instrument at solar observatories, also as a space payload for various solar missions. A high spectral resolution is invariably an important parameter for accurate vector magnetic field measurements and faster cadence is required for the study of dynamical evolution of structures (e.g., solar flares, sunspots etc.) on the Sun and hence better understanding on the physics behind their evolution.     

Considerations for the Short-Term Stability of Frequency Multipliers

The effects of frequency multiplication circuits on the short-term stability of an oscillator system are analyzed. The short-term stability of real components such as varactor multipliers are compared to the short-term stability of an ?ideal? frequency multiplier which maintains the stability of the basic oscillator. In addition, it is shown that positive feedback like that used in a synchronized oscillator, while useful for tracking, degrades short-term stability.     

High temperature alters the growth reaction of Pottia protonemata.

Under gravistimulation, dark-grown protonemata of Pottia intermedia revealed negative gravitropism with a growth rate of approximately 28 μm·h⁻¹ at room temperature (20 °C). In 7 days, the protonema formed a bundle of vertically oriented filaments. At an elevated temperature (30 °C), bundles of vertically growing filaments were also formed. However, both filament growth rate and amplitude of the gravicurvature were reduced. Red light (RL) irradiation induced a positive phototropism of most apical protonemal cells at 20 °C. In a following period of darkness, approximately two-thirds of such cells began to grow upward again, recovering their negative gravitropism. RL irradiation at the elevated temperature caused a partial increase in the number of protonemal cells with negative phototropism, but the protonemata did not exhibit negative gravitropism after transfer to darkness. The negative gravitropic reaction was renewed only when protonemata were placed at 20 °C. A dramatic decrease in starch amount in protonemal apical cells, which are sensitive to both gravity and light, occurred at the higher temperature. Such a decrease may be one of the reasons for the inhibition of the protonemal gravireaction at the higher temperature. The observation has a bearing on the starch-statolith theory.     

Characterization of complex organic compounds formed in simulated planetary atmospheres by the action of high energy particles.

A wide variety of organic compounds, which are not simple organics but also complex organics, have been found in planets and comets. We reported that complex organics was formed in simulated planetary atmospheres by the action of high energy particles. Here we characterized the experimental products by using chromatographic and mass spectrometric techniques. A gaseous mixture of CO, N2 and H2O was irradiated with high energy protons (major components of cosmic rays). Water-soluble non-volatile substances, which gave amino acids after acid-hydrolysis, were characterized by HPLC and mass spectrometry. Major part of the products were complex compounds with molecular weight of several hundreds. Amino acid precursors were produced even when no water was incorporated with the starting materials. It was suggested that complex molecules including amino acid precursors were formed not in solution from simple molecules like HCN, but directly in gaseous phase.     

Sampled-Data Control System Analysis Using the Poisson Summation Rule

A technique is presented which simplifies the analysis of sampled-data control systems. The use of a finite-term approximation to the Poisson summation rule, in conjunction with digital computer evaluation, is presented as a good alternative to use of the Z transform whenever frequency-domain analysis is required. The Poisson summation rule is reviewed and its application to sampled-data system analysis is discussed. The form of the computer program used in the analysis is presented, along with a design criterion to evaluate the accuracy of the technique. A detailed example of a typical application is presented.