Imprimir Republish


Small satellites make their mark

Nanosatellites are being launched for data collection missions ranging from environmental monitoring to biological systems testing

Nanosatellite AESP-14, developed by ITA and INPE, in test chamber

Léo RamosNanosatellite AESP-14, developed by ITA and INPE, in test chamberLéo Ramos

Invented in 1999 as an educational tool, CubeSats—nanosatellites in the form of a cube measuring 10 cm along each dimension, namely height, width and depth—have become a relatively inexpensive and quick tool for collecting space data. They are used for various purposes, ranging from the detection of electromagnetic signals that precede earthquakes to weather sensing systems, including the testing of biological systems, such as the production of bacterial proteins in space, and the observation of ground phenomena, among other applications. Since the first CubeSats were launched in 2003, when six projects piggybacked on the Russian launch vehicle Rockot, through April, 2014, there have been 130 launches, 65 of which were in 2013.

In Brazil, the program to build small satellites, begun in 2003 by researchers at the National Institute for Space Research (INPE) with support from the Brazilian Space Agency (AEB), is beginning to show concrete results with the forecast launch of four mini-satellites this year. The first, scheduled for launch on June 19, 2014, is the NanoSatC-BR1—an acronym for Brazilian scientific nanosatellite. The space sector borrowed the nano- prefix—representing a millionth of a millimeter—to designate very small satellites. The BR1, at just under a kilogram in weight, was conceived and developed by researchers at the INPE Southern Regional Center in partnership with the Federal University of Santa Maria (UFSM), in the state of Rio Grande do Sul. After performing tests, such as vibration, that simulate launch conditions, it was taken to Delft, in the Netherlands. Other tests will be performed there before the device is sent to Russia, where it will be launched by the DNEPR rocket, a former Soviet-Ukrainian nuclear missile converted into a commercial launch platform. “The rocket carries a main satellite and empty space is packed with several smaller satellites,” explains Otávio Durão, coordinator of engineering and space technology for the project at INPE’s headquarters in São José dos Campos, in the state of São Paulo.

The BR1 CubeSat will contain a board with three useful devices. One is a sensor called a magnetometer that will study the Earth’s magnetic field and its interaction with ionizing radiation from the Sun and stars. His goal is to study a phenomenon known as the South Atlantic magnetic anomaly, which occurs in the coastal region of southern Brazil. In this location, the researchers have noted the existence of a gap in the earth’s magnetosphere that allows ionizing radiation from space to arrive closer to the Earth’s surface. As a consequence, there is an increased risk of the presence of high-energy particles that can affect communications, signals from global positioning satellites (such as GPS), or power distribution networks or even cause failures in electronic equipment such as onboard computers. The CubeSat sensor will make measurements from a low orbit of about 600 km in altitude, flying over the Earth’s poles.

016-021_CAPA_nanosatelite_219-NOVO-1“We will also test, in space, the first two integrated circuits designed in Brazil for space use,” says Nelson Jorge Schuch, a physicist by training and general coordinator of the NanoSatC-BR Program for Development of CubeSats in the Southern Regional Space Research Center and manager of the INPE BR1 Project. One of the circuits receives commands from the ground with instructions to connect and disconnect the payload, camera etc. “The design method used for the development of this circuit protects it against space radiation, and this is what we want to test in flight,” says Schuch.

The other integrated electronic circuit is based on software developed by the microelectronics group laboratory at the Institute of Computer Science of the Federal University of Rio Grande do Sul (UFRGS), another development partner, which protects the hardware against failures caused by radiation. Two nanosatellite ground tracking and control stations, one in Santa Maria (RS) and another at the Aeronautics Technological Institute (ITA) in São José dos Campos, will monitor the BR1 CubeSat in orbit, tracking it and downloading the data it acquires in space. These stations are already receiving data from other satellites in orbit.

“At first we thought of working with small satellites, but then the concept of CubeSats—created by Professor Robert Twiggs at Stanford University—appeared, so we changed our strategy,” says Schuch. The platform was designed to be small and simple—which facilitates its construction by graduate students—and with a standard size: a cubic box with 10-cm edges that accommodates communication subsystems, solar panels, a battery and some extras, with a total weight of about one kilogram. “Over time, it became a space technological standard and paved the way for the assembly of other CubeSats,” says Durão.

Among the Brazilian nanosatellites preparing to be launched into space, one of them, the Tancredo-1, stands out because it was built by primary and middle school students at the Tancredo de Almeida Neves municipal school in the city of Ubatuba, on the north coast of the state of São Paulo. “The idea of assembling a satellite came up in a conversation with fifth-graders who worked on a scientific research project,” says math teacher Candido Osvaldo de Moura, coordinator of the project. The financial support of a local businessman who contributed R$16,500.00 was the starting point for the realization of the dream, which has lasted over five years and has involved 150 students. “We bought the components and the satellite was assembled here, piece by piece,” says the teacher.

Launching satellites from the Japanese module on the International Space Station

NASALaunching satellites from the Japanese module on the International Space StationNASA

In the United States there is a growing movement of space missions based on the CubeSat platform. In November 2013, for example, the space agency NASA put 29 satellites into orbit during a single mission, consisting of one military satellite and 28 CubeSats designed and built by various universities. One of them, called PhoneSat 2.4, used the hardware of a cellular telephone as its onboard computer. Private companies, like Planet Labs in San Francisco, founded in 2010 by three former NASA scientists, are also investing in this data collection platform. In February, 2014, it launched a fleet of 28 nanosatellites called Flock 1 from the International Space Station (ISS) to photograph the Earth continuously. According to the company, the images will allow identification of areas suffering environmental disasters and help improve agricultural production in developing countries (see more about this subject in the April 17, 2014 issue of Nature).

“The structure of a CubeSat is assembled with off-the-shelf components, which really reduces the cost of the project,” says Durão. The total cost of NanoSatC-BR1, for example, was around R$800,000. This amount includes components, development of ground station tracking and control software, construction of the ground station and the experiments that will become the payload, in addition to launching by the Russian rocket. Just the launch cost around R$280,000. For comparison, a CBERS series satellite, done in partnership with China for remote sensing, costs about $270 million and the risk of losing the entire project exists for both CubeSats and for large satellites. The CBERS-3, for example, was destroyed in December 2013 due to the failure of one of the Chinese launch vehicle’s engines. Similarly, the first Brazilian scientific nanosatellite, the Unosat-1, a joint project by the North Paraná (Unopar) and Londrina State (UEL) Universities, was destroyed in an accident with the launch vehicle VLS-1 in Alcântara, in the state of Maranhão, in 2003.

A second CubeSat from the NanoSatC program—BR2, twice the size of the first and with a larger payload capacity—is nearing completion and is expected to be launched in 2015. “The payloads have already been defined and are in development, and now we need to contract a launcher,” says Durão. One of them consists of a sensor for detecting particles in the ionosphere and the other is a subsystem to determine the attitude that defines the angular position of the satellite. The latter is essential, for example, for taking a photo or pointing an antenna. This subsystem, which is being built in Brazil for the first time, was developed through a partnership between INPE, the Federal University of Minas Gerais (UFMG) and the Federal University of the ABC (UFABC). It is a critical item for satellites because of its military application, which limits access to this technology to a few countries. The cost of assembling the BR2 platform, with engineering and flight models and ground station, totaled R$748,000.

Students at school in Ubatuba learn to assemble a TubeSat

Léo RamosStudents at school in Ubatuba learn to assemble a TubeSatLéo Ramos

The Renato Archer Center in Campinas also participated in the construction of the payload for NanosatC-BR1 and 2 through the Citar Project, whose goal is the development of integrated circuits with radiation protection for various applications, including space applications, for large satellites for telecommunications and other purposes. “These CubeSats and the others in the program will be used as test platforms in space for these circuits,” says electrical engineer Saulo Finco, of the Renato Archer Center, who coordinates the project. The BR1 already has one of the circuits developed under the Citar Project as part of its payload.

The other three Brazilian nanosatellites to begin orbiting this year are expected to be launched from the ISS, a platform orbiting at an altitude of 370 km. They will be launched by a robotic arm operated by the Japanese space module Kibo. One of these satellites is called Serpens (Space system for Conducting Research and Experiments with Nanosatellites), a project coordinated by AEB with the participation of the Federal University of Santa Catarina (UFSC), UFABC, UFMG and the University of Brasilia (UnB), in addition to the Federal Fluminense Institute in Campos de Goitacazes, Rio de Janeiro State, which is responsible for the stations that will receive data from the satellites.  International partners include the University of Vigo, Spain, Sapienza Università di Roma, Italy, and Morehead State University and California State Polytechnic University, both in the United States.

“We believe that implementation of the project will improve the training of students in new aerospace engineering courses, who will have contact with research groups with experience in this area,” says Gabriel Figueiró de Oliveira, an AEB grant recipient and responsible for the satellite development and assembly process. The universities will be responsible for implementation of the project. “Serpens, the name of a constellation [seen from the Northern Hemisphere], is the most challenging nanosatellite developed in Brazil,” says Professor Carlos Gurgel, director of satellites, applications, and development at AEB. The goal is to have it ready by the end of 2014. Its launch is scheduled for early December 2014. The first step towards the program’s first mission was taken in September 2013 with the start of the process for equipment purchasing, but the official project launch took place in the first week of December, during a workshop in which the international partners took part. “The images of the satellite being launched from the space station can be seen and shared by the students,” says Figueiró.

CAPA_40_2JG5829Léo RamosAll subsystems within Serpens, such as onboard computers, solar panels and other required components, were duplicated. And each of the sectors will carry a payload whose goal is to test a technological concept for CubeSats used for receiving and transmitting radio messages, which may be used for data collection in the future. “One of the sectors will carry a payload consisting of a transponder [device for data collection] assembled using an experimental architecture and low-cost components, some never tested in orbit, in the VHF [very high frequency] band,” says Figueiró. The other sector will contain an electronic communication device that has already been tested in orbit for this purpose, with a UHF band system, the same frequency range used for digital TV. “We want to test whether the UHF-band transponder can receive, store and process onboard information and then transmit it to the antennas installed at the universities.”

The second CubeSat to be launched this year, from the International Space Station, is the AESP-14, weighing about a kilogram and developed through a partnership between ITA and INPE. “The development of the nanosatellite is a way to encourage students to employ what they learn in the classroom,” says Professor Roberto Lacava, coordinator of the project and the ITA aerospace engineering curriculum, known at the institution by the acronym AESP. This same acronym was adopted as the name of the project, initiated in 2012 by the class that will graduate in 2014. “All electronic and mechanical subsystems were designed and built by students,” says engineer Cleber Toss Hoffmann, technical coordinator of the project at ITA. Only the radio-frequency modem, used in several CubeSats and compatible with the global amateur radio community, was purchased.

A master’s degree student at ITA, Hoffmann also teaches undergraduate courses and uses the project in his classes. The payload of the AESP-14 is an intellectual experiment. “Amateur radio operators worldwide will receive sentences recorded by Brazilian scientists,” says Lacava. Its development was funded by the National Council for Scientific and Technological Development (CNPq), with grants totaling R$150,000, and AEB, responsible for purchasing components, environmental testing, manufacturing and consumables, for a total of R$250,000. 

Nanosatellite AESP-14, developed by ITA and INPE, in test chamber

Léo RamosNanosatellite AESP-14, developed by ITA and INPE, in test chamberLéo Ramos

The third Brazilian satellite that will also be launched from the ISS, the Tancredo-1, weighs only 750 grams, is about 9 cm in diameter and 12 cm tall. Its shape resembles a cylinder, hence it is called a TubeSat. The platform, created by the American company Interorbital Systems, is a modular system consisting of a set of stacked plates and others to capture solar energy. “After talking with colleagues, community business leaders and contacts in city hall, I felt that we would be able to raise the funds needed to assemble it,” says Moura. The project began in 2010, when the teacher read in a magazine that Interorbital was selling a satellite assembly kit and would be responsible for putting the resulting satellite into orbit.

He then called the company to see if the prices were really those published and if it could be assembled in Brazil. “During the conversation, they told us that our students would be the youngest people in the world to do space research, but also that we would need technical assistance.” The student Maryanna Conceição Silva, 16, is one of those involved in the UbatubaSAT project since its inception. When it started, she was 12 and in fifth grade. “It’s really cool to learn how satellites are made,” she says about her experience. “At first it was very difficult, but not now.”

The technical support for the project came from INPE, which when contacted immediately jumped on the idea and began training the teachers, and then students. “We even had an engineering model of the satellite practically tested, but had problems at Interorbital and realized that there would be a long delay until it was launched, so we sought alternatives.” In total, around R$30,000 have been spent on the nanosatellite to date. 

And what was just an idea in the classroom transformed the lives of many students, like Maryanna. She was not very interested in science and technology beforehand, but now she wants to be space engineer. The students also wrote a scientific article as part of the project. In early 2013 it was submitted and accepted for presentation at the principal Japanese aerospace conference, in Nagoya. The trip was paid for by the United Nations Educational, Scientific and Cultural Organization (UNESCO). “The students did a tremendous amount of work and were invited to visit JAXA, the Japan Aerospace Agency,” says Moura. A documentary, currently being finalized, was filmed there, narrating the story of the construction of the satellite.

Students also visited NASA, in Pasadena, and Interorbital in Mojave, both in California. The TubeSat engineering model is complete and the flight model should be ready by July 2014, when it will be sent to Japan, where final tests will be performed before launch. The school is now holding a contest to choose the message to be transmitted in the amateur radio band. Moura is also working on making the Tancredo-2 a reality. The idea, he said, is to make a different model called a PocketCube, which was also developed by Twiggs at Stanford University.

Internal structure of NanoSatC-BR2

Léo RamosInternal structure of NanoSatC-BR2Léo Ramos

Other small satellites are under construction in Brazil, like Itasat 1, a joint project between INPE and ITA, expected to be launched in the second half of 2015. Originally, the objective of the project was to build a satellite using a conventional structure to collect environmental data. “After a while, the satellite was modified to use the CubeSat platform, as defined in international literature, which facilitates its reproduction in other experiments,” says Professor Elói Fonseca, manager of the project. “With this change, Itasat was able to take advantage of everything that had already been developed.” It weighs about six kilograms and is 10 cm by 22.6 cm by 34 cm (height), which corresponds to six BR1 CubeSat units. As payload, it will carry the same electromagnetic field radiation measurement sensors as the NanoSatC satellites. “That way, we can continue the experiments using a network of satellites,” says Fonseca.

The project will use a transponder developed by INPE’s Northeast Regional Center (CRN) in Natal, Rio Grande do Norte. “At the same time, our satellite will collect ground information using an imaging camera with a resolution of 80 meters at an altitude of 650 km, which will be its orbit.” These images may be used for relief and atmosphere studies and university experiments. 

The Natal CRN, responsible for the Brazilian environmental data collection system, is also part of the Brazilian CubeSat movement. Since early 2011, researchers at the regional center, coordinated by Manoel Mafra de Carvalho, have been working on the Conasat project—a constellation of six nanosatellites to collect environmental data, each being a cube with edges measuring 20 cm and weighing 8 kg. The project’s goal is to ensure the continuity of environmental data collection, since of the two satellites currently in operation, INPE’s SCD1 and 2, only one is working as planned. The two satellites, made in the 1990s, have a cylindrical shape, measure 1 meter high by 1.5 meter in diameter and weigh over 100 kg. “Conasat performs the same functions as SCD, at a lower cost,” says Carvalho, who is also coordinator of the CRN. Before deciding that the satellite would use the CubeSat format, a study was done to evaluate the feasibility of having a data-collection transponder embedded in the nanosatellite. “In space, the transponder will receive signals from platforms scattered throughout Brazil and the Atlantic and relay them to our receiving stations in Alcântara and Cuiabá,” says Carvalho. After the stations receive them, they are processed and sent to users. The cost of Conasat design and assembly will be about R$5 million, including launch. It is expected that the first satellite in the constellation will be launched in 2016.