Construção e validação de um receptor GPS para uso espacial

Global Positioning System, or simply GPS, it is a radionavigation system developed by United States for military applications, but it becames very useful for civilian using. In the last decades Brazil has developed sounding rockets and today many projects to build micro and nanosatellites has appeared. This kind of vehicles named spacecrafts or high dynamic vehicles, can use GPS for its autonome location and trajectories controls. Despite of a huge number of GPS receivers available for civilian applications, they cannot used in high dynamic vehicles due environmental issues (vibrations, temperatures, etc.) or imposed dynamic working limits. Only a few nations have the technology to build GPS receivers for spacecrafts or high dynamic vehicles is available and they imposes rules who difficult the access to this receivers. This project intends to build a GPS receiver, to install them in a payload of a sounding rocket and data collecting to verify its correct operation when at the flight conditions. The inner software to this receiver was available in source code and it was tested in a software development platform named GPS Architect. Many organizations cooperated to support this project: AEB, UFRN, IAE, INPE e CLBI. After many phases: defining working conditions, choice and searching electronic, the making of the printed boards, assembling and assembling tests; the receiver was installed in a VS30 sounding rocket launched at Centro de Lançamento da Barreira do Inferno in Natal/RN. Despite of the fact the locations data from the receiver were collected only the first 70 seconds of flight, this data confirms the correct operation of the receiver by the comparison between its positioning data and the the trajectory data from CLBI s tracking radar named ADOUR

Efeitos da microgravidade em plantas de cana-de-açúcar

Sugarcane (Saccharum spp.) is a plant from Poaceae family that has an impressive ability to accumulate sucrose in the stalk, making it a significant component of the economy of many countries. About 100 countries produce sugarcane in an area of 22 million hectares worldwide. For this reason, many studies have been done using sugarcane as a plant model in order to improve production. A change in gravity may be one kind of abiotic stress, since it generates rapid responses after stimulation. In this work we decided to investigate the possible morphophysiological, biochemical and molecular changes resulting from microgravity. Here, we present the contributions of an experiment where sugarcane plants were submitted to microgravity flight using a vehicle VSB-30, a sounding rocket developed by Aeronautics and Space Institute teams, in cooperation with the German Space Agency. Sugarcane plants with 10 days older were submitted to a period of six minutes of microgravity using the VSB-30 rocket. The morphophysiological analyses of roots and leaves showed that plants submitted to the flight showed changes in the conduction tissues, irregular pattern of arrangement of vascular bundles and thickening of the cell walls, among other anatomical changes that indicate that the morphology of the plants was substantially influenced by gravitational stimulation, besides the accumulation of hydrogen peroxide, an important signaling molecule in stress conditions. We carried out RNA extraction and sequencing using Illumina platform. Plants subjected to microgravity also showed changes in enzyme activity. It was observed an increased in superoxide dismutase activity in leaves and a decreased in its activity in roots as well as for ascorbate peroxidase activity. Thus, it was concluded that the changes in gravity were perceived by plants, and that microgravity environment triggered changes associated with a reactive oxygen specie signaling process. This work has helped the understanding of how the gravity affects the structural organization of the plants, by comparing the anatomy of plants subjected to microgravity and plants grown in 1g gravity

Estudo do acoplamento entre superfícies seletivas de frequência assimétricas em estruturas de multicamadas

This work presents the development of new microwaves structures, filters and high gain antenna, through the cascading of frequency selective surfaces, which uses fractals Dürer and Minkowski patches as elements, addition of an element obtained from the combination of the other two simple the cross dipole and the square spiral. Frequency selective surfaces (FSS) includes a large area of Telecommunications and have been widely used due to its low cost, low weight and ability to integrate with others microwaves circuits. They re especially important in several applications, such as airplane, antennas systems, radomes, rockets, missiles, etc. FSS applications in high frequency ranges have been investigated, as well as applications of cascading structures or multi-layer, and active FSS. In this work, we present results for simulated and measured transmission characteristics of cascaded structures (multilayer), aiming to investigate the behavior of the operation in terms of bandwidth, one of the major problems presented by frequency selective surfaces. Comparisons are made with simulated results, obtained using commercial software such as Ansoft DesignerTM v3 and measured results in the laboratory. Finally, some suggestions are presented for future works on this subject

Estudo comparativo de técnicas de cascateamento de superfícies seletivas em frequência

This work presents a theoretical and numerical analysis for the cascading of frequency selective surfaces, which uses rectangular patches and triangular Koch fractals as elements. Two cascading techniques are used to determine the transmission and reflection characteristics. Frequency selective surfaces includes a large area of Telecommunications and have been widely used due to its low cost, low weight and ability to integrate with others microwaves circuits. They re especially important in several applications, such as airplane, antennas systems, radomes, rockets, missiles, etc.. FSS applications in high frequency ranges have been investigated, as well as applications of cascading structures or multi-layer, and active FSS. Furthermore, the analyses uses the microwave circuit theory, with the Floquet harmonics, it allows to obtain the expressions of the scattering parameters of each structure and also of the composed structure of two or more FSS. In this work, numeric results are presented for the transmission characteristics. Comparisons are made with experimental results and simulated results using the commercial software Ansoft Designer® v3. Finally, some suggestions are presented for future works on this subject

Método dinâmico aplicado para antenas cilíndricas

Nowadays there has been a major breakthrough in the aerospace area, with regard to rocket launches to research, experiments, telemetry system, remote sensing, radar system (tracking and monitoring), satellite communications system and insertion of satellites in orbit. This work aims at the application of a circular cylindrical microstrip antenna, ring type, and other cylindrical rectangular in structure of a rocket or missile to obtain telemetry data, operating in the range of 2 to 4 GHz, in S-band. Throughout this was developed just the theoretical analysis of the Transverse transmission line method which is a method of rigorous analysis in spectral domain, for use in rockets and missiles. This analyzes the spread in the direction "ρ" , transverse to dielectric interfaces "z" and "φ", for cylindrical coordinates, thus taking the general equations of electromagnetic fields in function of e [1]. It is worth mentioning that in order to obtain results, simulations and analysis of the structure under study was used HFSS program (High Frequency Structural Simulator) that uses the finite element method. With the theory developed computational resources were used to obtain the numerical calculations, using Fortran Power Station, Scilab and Wolfram Mathematica ®. The prototype was built using, as a substrate, the ULTRALAM ® 3850, of Rogers Corporation, and an aluminum plate as a cylindrical structure used to support. The agreement between the measured and simulated results validate the established processes. Conclusions and suggestions are presented for continuing this work

As Ciências Espaciais, o saber e o fazer docente no ensino fundamental

This study aims to include topics related to Space Science in elementary education from an experiment that aims to rescue the science teachers in public schools of São Tomé, RN, a taste for experimentation and exploration of advanced technologies. During this research with teachers found that they knew enough about the subject, but this knowledge was restricted to the events disclosed by the media. Regarding scientific knowledge, that same surface, they had many conceptual difficulties which hindered the approach of these topics in their classes. To overcome this difficulty, a workshop was held where teachers had the opportunity to discuss the historical aspect of Space Science, some physical concepts related to it, and the conduct of experiments with PET bottle rockets that recover from the curiosity typical of how the science. The results were outlined in the form of Planning Didactic built by teachers and using themes related to space science, from there, discussing content already provided in the composition of the schools curriculum. Therefore, this work allowed the teachers a minimum training required for them to not only reproduce, but readjusted and build, from this, their own paths in the classroom at the fundamental level

Otimização do controle do diagrama de radiação de radares de varredura para rastreio de foguetes usando o método GAMMC para o Caso Planar (GAMMC-P)

Launching centers are designed for scientific and commercial activities with aerospace vehicles. Rockets Tracking Systems (RTS) are part of the infrastructure of these centers and they are responsible for collecting and processing the data trajectory of vehicles. Generally, Parabolic Reflector Radars (PRRs) are used in RTS. However, it is possible to use radars with antenna arrays, or Phased Arrays (PAs), so called Phased Arrays Radars (PARs). Thus, the excitation signal of each radiating element of the array can be adjusted to perform electronic control of the radiation pattern in order to improve functionality and maintenance of the system. Therefore, in the implementation and reuse projects of PARs, modeling is subject to various combinations of excitation signals, producing a complex optimization problem due to the large number of available solutions. In this case, it is possible to use offline optimization methods, such as Genetic Algorithms (GAs), to calculate the problem solutions, which are stored for online applications. Hence, the Genetic Algorithm with Maximum-Minimum Crossover (GAMMC) optimization method was used to develop the GAMMC-P algorithm that optimizes the modeling step of radiation pattern control from planar PAs. Compared with a conventional crossover GA, the GAMMC has a different approach from the conventional one, because it performs the crossover of the fittest individuals with the least fit individuals in order to enhance the genetic diversity. Thus, the GAMMC prevents premature convergence, increases population fitness and reduces the processing time. Therefore, the GAMMC-P uses a reconfigurable algorithm with multiple objectives, different coding and genetic operator MMC. The test results show that GAMMC-P reached the proposed requirements for different operating conditions of a planar RAV.