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Space lens

A Brazilian-made camera that takes photographs of the earth to equip Chinese-Brazilian satellite Cbers-3

eduardo cesarLens undergoing anti-reflection treatment at Opto Eletrônicaeduardo cesar

The launching of the next Earth Resources Chinese-Brazilian Satellite/Cbers-3, scheduled for April 2010, will be a major achievement not only for the Brazilian space program, – as this is the fourth satellite of the series, most of which is being developed in Brazil – but also for Opto Eletrônica, a company headquartered in the city of São Carlos, in the State of São Paulo. The enterprise manufactured one of the satellite’s cameras, which can photograph the earth’s crust. The camera, called an MUX multi-spectrum camera, is a major technological leap for Brazilian industry, because it is the first equipment of its kind to be entirely made in Brazil. The images of Brazilian and Chinese territories will be used for environmental monitoring and the management of natural resources. To this end, the image will have a resolution of the earth’s surface with a 20-meter side, a feature responsible for sharpness, within a parameter that is quite significant, taking into account that the Cbers-3 will orbit the earth at an altitude of 800 kilometers. This is equivalent to seeing a train on the surface of the Earth or a fly at some 400 meters. The imaged width of the strip, which is the extension of the territory seen in one line on the image, is 120 kilometers wide.

“The production of the MUX by Opto is in line with the directives of the Brazilian space program, the objective of which is to foster the development of state-of-the-art technology within Brazilian industry, enabling our companies to become competitive in the international space market,” points out engineer Mario Selingardi, the technical expert responsible for the project at Brazil’s National Space Research Institute (Inpe). In addition, the manufacturing of this sub-Cbers-3 system by a national partner helps the country become technologically independent in highly sensitive areas, from the strategic point of view. The current stage of the camera’s development entails functional tests of the MUX engineering model. This model is a prototype that comes before the qualification model and the equipment that will actually fly. The engineering model is scheduled to be sent to China by July, where it will be submitted to electric tests for integration with the other systems. In the experiments conducted here, the camera is submitted to trials in order to check whether it can withstand the launch loads and the temperature and vacuum of space, besides verifying whether it fulfills aging and electromagnetic compatibility requirements while maintaining its functional performance. According to Inpe, the trials conducted at the institute’s Tests and Integration Laboratory showed that no degradation occurred in the equipment’s optical performance. “The camera successfully passed the test,” said Inpe’s Selingardi.

eduardo cesarMUX camera: 115 kilos and 1.10 meters longeduardo cesar

These experiments are a major step forward in the long journey that began in December 2004, when Opto was the winning bidder of the international tender for the manufacturing of the camera. Design on the MUX began in the following month, and the first stage of the work (the conclusion of the preliminary project) was ready at the end of that year. To illustrate the complexity of the preliminary project, suffice it to say that it comprised more than 450 documents and 16 thousand pages. “One of our great difficulties was to transform this huge pile of documents and analyses into an equipment design that would actually work,” says engineer Mário Stefani, a director of Opto and MUX project coordinator. “The analyses were very detailed, because they had to predict very accurately how the camera would work and if it would be able to provide the requisite useful life in the hostile environment of outer space,” he says.

Robust project
The camera only barely resembles professional and personal cameras. It weighs no less than 115 kilograms, is 1.10 meters long, 80 centimeters wide and 55 centimeters high. A robust and highly sophisticated device, it is divided into three modules. The camera itself, the acronym of which is RBNA, is comprised of lens, focal plane, thermal system, radiators, heaters and shielding, among other components. The RBNB segment controls the temperature and the focal adjustment system, whereas the RBNC processes and packages the images to be sent back to Earth. The camera’s optical and mechanical structure, as well as the testing equipment, are being designed and developed by the Opto engineering team. The electronic design was also prepared by the company, although the components are imported. The camera’s image sensor and the electronic chips, qualified for use in outer space, were provided by the Inpe. “The Cbers-2 (in orbit since September 2007) was equipped with a WFI camera, whose electronic design was developed in the country; its optical module, focal plane and proximity electronics were imported from the United States. Nowadays, Opto, together with Equatorial Sistemas, a company headquartered in the city of São José dos Campos, is part of the pool of enterprises responsible for the expanded version of the camera, which will equip the Cbers-3. Our company is responsible for the design and construction of the optical-electronic block,” says Stefani. In addition to the MUX and the WFI, two other cameras will be part of Cbers-3’s useful load: the PAN, with a panchromatic band, and the IRS, the image resolution sweep camera, both of which are being manufactured by Chinese firms. The MUX camera on the Cbers-2B launched in September of last year was also made in China. However, there is a difference between this and the equipment manufactured by Opto. The Brazilian camera “sees” in four colors, recording images in blue, green, red and infrared; the Chinese camera lacked the band. “The inclusion of the blue band simultaneously with the other originally planned three bands was controversial and costly. In addition, the complexity of the optical design has increased significantly, demanding higher precision and manufacturing control,” says Stefani. This huge effort is justified. The blue band can provide more clearly defined images of the vegetation and water resources, which helps keep track of agricultural production. When it goes into operation, the MUX will generate images that will be used for hydrologic, forestal, agricultural, perimetral, urban and mineral control and monitoring. This data will help identify slashing and burning of land, deforestation, or illegal use of land; it will also aid sustainable planning.

eduardo cesarSets of special lens produced in São Carloseduardo cesar

Because of the pioneering aspects of the venture and the complexity of the MUX, a number of challenges had to be – and are still being – overcome in order to manufacture the subsystem. One of the chief challenges concerns the optical precision of the camera: the lens must be manufactured to a precision of tenths of thousandths of a millimeter. The assembly of the lens must not only follow a rigid positioning, but must also be reliable enough to withstand the rocket’s launching load, when vibration levels reach 56 G (or 560 m/s²). The image sensor, comprised of roughly 6 thousand tiny square plates measuring approximately 13 thousandths of a millimeter on each side, also required top-notch skills from the company’s engineers. A tiny speck of dust on the sensor can create a “shadow” or “blind” this image element. This is why the assembly of the camera and the trials must be conducted in a dust-free environment. “Opto built 450 square meters of clean rooms for the manipulation of the optical precision systems. The number of particles in these systems is below one thousand per cubic meter, and they measure less than 1 micron,” says Stefani.

Strict law
Another challenge that had to be overcome was related to the boycott, by U.S. companies, of some of the camera’s parts and components, on account of the International Arms Trafficking Regulation/Itar. This regulation explicitly establishes, among other provisions, that remote sensor satellites or cameras, even when used for civilian purposes, must comply with the strategic and security interests of the United States. If a program is seen as going against these interests, American solutions or components are banned, by law, from being available. The Itar law is very strict, and can result in multi-million dollar fines and prison terms for the engineers involved. “The sale of several critical components, essential for the Cbers, was suddenly banned. We faced various several embargoes in the case of the MUX. One was the voltage converter for use in outer space. After the product had been ordered, paid for and was ready for shipment, it could not be sent to Brazil and the supplier had to return the money. That part of the project had to be entirely redone,” says physicist Jarbas Caiado de Castro Neto, Opto’s CEO. “At the time, the decision caused a huge problem, but now we realize that the Itar law is an opportunity for us to develop our own solutions and new approaches to the project.”

eduardo cesar One of the lenses for the prototype of the MUX cameraeduardo cesar

A team of 45 people, comprising physicists, mechanical, electronic, materials and production engineers, and optical, electronic and mechanical technicians is involved in building the MUX. A new stage of the project – entailing the building of the qualification model – will be started after the conclusion of the trials on the engineering model, built from similar but less expensive components. The design is the same, but the materials and components are specific for outer space. This new model, to be completed by July 2008, will be submitted to a battery of tests until it is considered ready to go up into space. After being approved, the qualification model will be discarded, because its components will have been submitted to extreme mechanical, thermal and electronic loads, and therefore will no longer be qualified and reliable to fly in outer space. But Opto will by then be qualified to build the flight model for the satellite. “It will be manufactured through the same processes, tools and operating sequence used to make the qualification model,” says Inpe’s Selingardi. Three flight models will be manufactured: one for the Cbers-3, another one for the Cbers-4, scheduled for launching in 2013, and a third spare one. Inpe and Opto have a R$ 75 million contract.

The manufacturing of the MUX is the main project for Opto’s Aerospace Division, created in 1994 to conduct product R&D and provide optical-electronic and laser consulting services for the aerospace industry. In 2007, the company’s revenues amounted to R$ 45 million. “Our technology is based on the three following cornerstones: optics, fine mechanics and electronics, which allow us to develop products for the ophthalmic, fine film, aerospace and defense industries,” Castro points out. The company manufactures products such as retinographs, retina surgery lasers, fine anti-reflecting films for ophthalmologic and dental use, surgical microscopes, laser distance meters, and defense systems. “We have thousands of clients from the area of fine films, most of which are manufacturers of eyeglasses and opticians. In the market segment of reflectors for dental use, at one point, we held nearly 50% of the global market share. However, due to fierce competition from Chinese products, our market share has dropped radically in the last few years,” says the president of Opto. Opto sells its medical equipment in 64 countries, through branches or distributors. The company, founded in 1985 by five friends, is based on highly qualified staff. Of its 345 employees, 42 have Master’s degrees, Doctorates or MBAs, and the others have graduate degrees or special technical skills.