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Space

Space conquests

Uniespaço project develops technological innovations for rocket and satellite projects

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By the end of the year, if everything goes well, the prototype of a new aluminum rocket, totally designed and built in Brazil, will be ready to be launched into space from the Barreira do Inferno Launch Center, in Natal, in Rio Grande do Norte. With 3.2 meters in length, the vehicle is being finalized by researchers from the Mechanical Engineering Department of the University of Brasilia (UnB). It is part of one of the 15 projects that make up the Uniespaço Program, run by the Brazilian Space Agency (AEB), which has the objective of promoting the inclusion of the Brazilian scientific community in the Brazilian Space Program and to foster the development of new technologies for the sector. After almost three years of researches – and the involvement of about 50 researchers from various universities and research institutes -, the results are appearing.

“The 15 projects have great applicability in activities of the AEB in areas like launches of space vehicles and satellites, onboard computers for application in space, sensors and actuators for attitude control systems in satellites and materials intended to support high temperatures”, says José Bezerra Pessoa Filho, head of the Space Systems Division of the Aeronautics and Space Institute (IAE), of São José dos Campos, and a member of Uniespaço’s Technical-Scientific Commission.

Besides the development of these new technologies, the projects also contribute towards training specialized labor for the space program, which boasts a bold agenda of missions for the next few years. By 2014, the country intends to sponsor the launch of three versions of Satellite Launch Vehicles (SLV), besides putting into orbit or taking part in joint works on a dozen of scientific, meteorological, telecommunications and Earth observation satellites. One of these macroprojects is the second generation of China-Brazil Earth Resources Satellites (CBERS 3 and 4), forecasted to be launched in 2008 and 2011, respectively, taking on board cameras totally produced in Brazil (please see feature on page 73). Before that, the National Institute for Space Research (INPE) expects to launch, in May 2007, the CBERS-2B, to replace the second satellite of the series, which went into space in 2003.

The rocket designed by the UnB is a good example of the success of Uniespaço, which received a budgetary allocation of R$ 1 million from the federal government to finance the projects. Designed to exceed an altitude of 10 thousand meters, the vehicle has a technology that is unprecedented in Latin America: its rocket engine is endowed with a hybrid system that works on a mixture of a liquid oxidant, nitrous oxide (N2O), and a solid fuel, paraffin, similar to that used in the manufacture of candles. The main advantage of this kind of fuel is that it is cheaper and simpler to be operated. “Thanks to a valve that controls the injection of the liquid oxidant, combustion can be interrupted at any moment, and this makes it safer to handle”, says Professor Carlos Alberto Gurgel, the coordinator of the project. Not to mention that the hybrid fuel is neither toxic nor pollutant.

The work began to be developed by undergraduate mechanical engineering students from the UnB in 2000, under the auspices of the Uniespaço Program, and was led by engineer Ricardo Contaifer. The results may, in the future, help the country to acquire technology for using liquid fuels in rockets, which are the one most used in space vehicles.

The research conducted by mechanical engineer Carlos Henrique Marchi, the coordinator of the postgraduate program in mechanical engineering at the Federal University of Paraná (UFPR), is also associated with the development of large-sized rockets, bigger than the SLV, which use liquid oxygen and hydrogen as propellants. The main purpose of this project is to create applications (software) that make it possible to design these engines, used nowadays by the French Ariadne rocket and by the American space shuttles, amongst others. “The research has the objectives of foreseeing the thrust (or force) produced by the engine, the maximum temperature reached by the walls of this mechanism, and the fall in pressure of the flow of the liquid refrigerant along the tubes around the rocket engine”, Marchi highlights.

According to the researcher, there are few research groups at a world level that are poring over the three subsystems: the flow of the engine together with the conduction of heat to the wall and the flow in the tubes. “And even these groups are not doing an estimate of the numerical errors involved in the solution of the problem”, he stresses. “The numerical error of a simulation has to be estimated. This makes it possible to make an adequate comparison between the experimental results and the numerical ones and verify whether the simulation model reproduces the real phenomenon.”

Another important research for the country to advance in space exploration is unwinding in the laboratories of the Federal University of Rio Grande do Norte (UFRN). There, electrical engineer Francisco das Chagas Mota is coordinating a group that is developing a GPS (Global Positioning System) receiver) to be used in space vehicles like probe rockets and satellites. “The equipment serves to determine with precision the speed and the position of the rocket or of the satellite in space. Its main innovation is the incorporation of certain characteristics, mainly in the software, that are not present in commercially available receivers, such as the capacity for working at high altitudes and at high speed without losing synchronism with the satellite signal”, Mota explains.

The project is at the final stage of assembling the machine, and unless there are unforeseeable events, the receiver will be installed in a probe rocket to be sent into space next year, from Barreira do Inferno. “The probe rockets currently launched in Brazil use imported GPS receivers. With this project, we will master the GPS technology that is suitable for these vehicles and, in future, for use in satellites.”

Physicist Marcelo Carvalho Tosin, from the Electrical Engineering Department of the State University of Londrina (UEL), and Professor Francisco Granziera Júnior are working on the development of an artifact with potential to be embarked in aerospace vehicles. It is an apparatus capable of calculating attitude in real time from digitalized signals from micro-electro-mechanical systems (MEMS). “The attitude of an object is the orientation that this shows in relation to an axis of fixed coordinates (latitude, longitude and altitude)”, the researcher explains. Knowing the attitude and the movement of an object is important in several applications, such as, for example, for a pilot to recognize and to foresee its trajectory during the flight.

One determinant of attitude is usually made up of sensors and a unit for the processing of the signals from these sensors. In the case of the apparatus developed in Londrina, the system uses information in 3D about the terrestrial magnetic field, the gravitational field and the angular velocity for calculating the attitude. To do so, a set of magnetometers, an instrument intended to measure the intensity of the magnetic field, accelerometers, used to measure accelerations, and gyrometers, which supply information about the angular velocity in a given direction, are employed as a set with a system of digitalization and data processing. One prototype is now ready, and the project will be finalized with the implementation of algorithms for calibrating and aligning sensors.

According to Marcelo Tosin, although it has aerospace applications, the attitude determination system that he is developing is also aimed at terrestrial and personal use, such as personal navigation systems, security systems for monitoring cargoes, and devices for interacting with computer games and toys. “The aerospace sector is one of those that have contributed most to aggregate new technologies with mass consumer products, such as household appliances, cars and clothing, amongst others. The use of low cost MEMS sensors in a given attitude determination system and the possibility of employing them in people’s day-to-day products are two great innovations of this project”, Tosin says.

inpeCylindrical structures
One of Uniespaço’s most innovative projects is carried out in a partnership between the Federal University of Minas Gerais (UFMG) and the Nuclear Technology Development Center of the National Nuclear Energy Commission (CDTN/CNEN) and deals with the development of composite materials (made up of the mixture of materials of a different nature) of interest to the aerospace sector, of which carbon nanotubes are one of the components. Carbon nanotubes are cylindrical structures made up of carbon atoms, with a diameter of about 1 nanometer (1 millimeter divided 1 million times) and unlimited length. They may have metallic or semiconductor characteristics and are excellent heat and electrical conductors, besides having extreme resistance to traction and being able to be twisted and folded without a break occurring.

All these properties make carbon nanotubes candidates for strengthening polymeric composites for strategic sectors, like the epoxy resin or phenolic resin nanocomposites used in the fuselages of rockets and other aerospace vehicles. The resistance of the structure of the aircraft is particularly important on the reentry of the vehicles into the terrestrial atmosphere. “The use of composite materials of polymeric resin and carbon nanotubes, initially in strategic places of the structure of space vehicles, could bring gains in mechanical properties and in the dissipation of heat and electrostatic charge, minimizing the damages caused by the bombardment of ions”, says Clascídia Furtado, a researcher from the CDTN and one of the coordinators of the project, together with Professor Glaura Silva, from UFMG. The benefits of the use of a covering of nanotubes on the structure of the aircraft also represents a functional barrier of low weight to prevent electromagnetic interferences.

The nanotubes may also resolve the structural damages and the damages from the alteration of electronic devices in aircraft due to the phenomenon of lightning (electrical discharges occurring in thunderstorm). Highly conducting materials based on carbon nanotubes could dissipate the charges arising from an electrical discharge. “The great challenge is precisely to transfer the set of properties from the nanotubes to a composite system, which depends mainly on the degree of dispersion of the nanotubes and on the interfacial interactions between them and the polymeric matrix”, says Clascídia. “We are working on what is called “pre-competitive” research, in which the technology is being developed at the same time as the basic research.” According to the researcher, Brazil is not backward in relation to other countries in the quest for such technologies.

Space photography page
The China-Brazil Earth Resources Satellites (CBERS), versions 3 and 4, developed in cooperation with China, are going to go up into space with two of the four imaging cameras designed and constructed exclusively in Brazil. One of them, the Multi-Spectral Camera, in the middle of this year already passed the first tests at the National Institute for Space Research (INPE).

Developed by Opto Eletrônica, a technology-based company from the city of São Carlos, São Paulo, the new camera generates images in four bands of the electromagnetic spectrum, from blue to near infrared. With a resolution of 20 meters, it is intended for environmental monitoring and management of natural resources. Its visual field, the strip of ground visualized by the camera, is 120 kilometers in width. “It is the first camera with these characteristics entirely developed and produced in Brazil”, claims Mario Luiz Selingardi, and engineer from INPE and the technical manager of the MUX Project.

The second camera will be an update of the Wide Field Imager (WFI). It is being developed jointly by Opto Eletrônica, responsible for the optical part, and by Equatorial Sistemas, a company from São José dos Campos specialized in the manufacture of space artifacts and that was recently acquired by the French company EADS. It is a medium resolution camera, with 64 meters, and high range of cover. It works as a wide angle lens camera and has a visual field of 866 kilometers.

The amount invested in the development of the two cameras amounts to R$ 90 million. “The manufacture of this equipment in Brazil represents an important technological gain. The companies involved qualify themselves in cutting edge area, which drives the development of other products”, points out Marcos Bertolino, an engineer from INPE and the technician responsible for the WFI project.

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