Support for development of technologies with aerospace applications

FAPESP and FINEP will fund 15 research projects related to on-board instruments for a Brazilian satellite, space electronics and optics, and attitude and orbit control, among others.

By Diego Freire  |  Agência FAPESP – In recent years, Brazil has made significant progress in the development of aerospace imaging technology, with local players fabricating equipment for producing high-resolution images from altitudes of up to 780 km. The nation’s aerospace capabilities could be further enhanced thanks to research now under preparation by scientists and entrepreneurs in the State of São Paulo, with support from FAPESP and FINEP, the Brazilian Innovation Agency.

Fifteen projects submitted by ten companies based in São Paulo State, established at least 12 months before the call and with up to 250 employees, have been selected in a call for proposals issued by the PIPE/PAPPE Grant Program, a partnership between FAPESP and FINEP.

The proposals sought to respond to technological challenges related to on-board instruments for the EQUARS mission mounted by the National Space Research Institute (INPE) to study the equatorial atmosphere, including space electronics and optics, propulsion, digital transponders and antennas, power supply, systems integration, and attitude and orbit control.

One of the participating companies is Opto Tecnologia Optrônica Ltda., the space and defense division of Grupo Opto Eletrônica S.A., which was recently acquired by Akaer Engenharia S.A. Based in São Carlos, Opto develops products that combine optics, laser technology, electronics and precision mechanics for medical, industrial, aerospace and defense applications.

All three of the company’s selected projects aim to upgrade on-board cameras in Brazilian satellites, which currently use refractive optical systems consisting only of lenses.

“Opto’s projects to be funded by FAPESP and FINEP will develop genuinely Brazilian technology to fulfill the requirements of PESE, Brazil’s Strategic Space Systems Program, among others. Support for this type of technology is vital for the local development of solutions that mitigate the technological risks these missions involve,” said Henrique Cunha Pazelli, who is responsible for one of the company’s three selected projects.

Piece by piece

The Brazilian space program’s requirements in terms of high-resolution cameras with a wide field of view and short-wave infrared (SWIR) sensors can be met only by reflective optical systems consisting of mirrors or by catadioptric optical systems, which combine refraction and reflection via lenses (dioptrics) with curved mirrors. SWIR sensor images allow, for example, the ground to be seen through dense smoke during a fire.

It will be necessary to invest in refinements to the equipment currently in use in order to upgrade existing technology for more powerful cameras. High-resolution multi-spectral cameras are cutting-edge technology for earth observation satellites and use a type of design known as three-mirror anastigmat (TMA). To this end, Opto proposed a project entitled “Development of a TMA-type reflective optical system for orbital imaging instruments”.

The new system will be very high in resolution, with a wider field of view, and be free of interference. For this to be feasible, however, a number of technologies will have to be mastered, such as the fabrication of large, lightweight optical components with off-axis reflector alignment.

Another innovation by Opto that is to be funded by the FAPESP-FINEP partnership will come from the project “Development of a single-mirror lateral aiming system for optical imaging from space”. The system will consist of a mirror coupled to a rotation mechanism comprising a stepper motor (for very precise movement) and data acquisition and control electronics. The project encompasses the fabrication, assembly and prototype testing of this system.

“Fine manipulation of the mirror’s angular position increases the frequency with which mapped areas can be revisited to observe a target of study repeatedly at short intervals and acquire images of the same scene from different angles in order to extract three-dimensional data for the area,” said Daniel Moutin Segoria, the engineer responsible for the project.

The intervals can also be varied to observe plantations with crops harvested at different times or areas with some kind of anomaly, he went on, adding that mechanisms capable of ensuring accuracy, repeatability and stability while the system is operating will have to be carefully studied, given the characteristics of the environment in which the equipment will be used.

“Mechanical systems used in space require bearings and other moving parts that must be fabricated using specific materials and surface treatments depending on the application for which each component is intended,” Segoria said.

Heat control

The unstable environment may also lead to misalignment of the optical systems in satellite imaging instruments, causing a loss of image quality. In addition to the challenges of designing an optical system that guarantees good results in microgravity, the firm’s engineers must also ensure that the system is sufficiently robust to maintain the quality verified in acceptance tests after it has been subjected to high levels of vibration while being launched into space.

“The difficulty of designing a system that has the same characteristics on the ground and in space often leads engineers and optical designers to include some kind of mechanism for realigning the optical system after launch, typically an on-board focus adjustment system,” Pazelli said.

The conventional focus adjustment technique relies on a stepper motor coupled to precision actuators, but this approach consumes too much power and is costly because of its technological complexity.

Opto’s third selected project, entitled “Temperature-controlled focus adjustment system”, will therefore develop a focus adjustment mechanism based on the application of heat control to an element of the optical system.

The inspiration for this system will be a reflecting telescope, which is configured such that electromagnetic radiation is reflected by the primary mirror and intercepted by the secondary mirror before reaching the main focus. After it is reflected by the secondary mirror, the radiation converges to a focal point located behind the primary mirror.

The first step will be to build proofs of concept to test the hypotheses suggested, followed by the construction of an engineering model that integrates all developed solutions into a prototype for comprehensive testing to assess their functionality.

The list of companies and projects can be viewed at fapesp.br/10643 (in Portuguese).