IRAZU CubeSat Mission
The Central American Association of Aeronautics and Space (ACAE : Asociación Centroamericana de Aeronáutica y del Espacio), in partnership with academy, industry and the government, have identified the promotion of the aerospace as a very promising strategy for economic, scientific and technological development in Costa Rica. Several studies have identified actions to enable the development of the aerospace sector in the country. Among them, a practical demonstration of the technical capabilities to develop a space engineering project is considered mandatory.
The Irazú project is an innovative mission taking place in Costa Rica, which aims to launch the first Central American satellite in orbit by 2018. This mission, declared of national interest by the president of the country, is being led by ACAE and ITCR (Costa Rica Institute of Technology). This project has two main objectives: going through the space project lifecycle and demonstrating a platform to measure the effects of climate change in Costa Rican rainforests, amid the efforts of this country to become the first carbon-neutral nation in the world. 1)
Costa Rica has played a leading role in the conservation of natural resources. Recent evidence of this includes the country's continuing reforestation, increasing its forest coverage from 40.8% in 1986 to 51.4% in 2010, and its ambitious objective to become a carbon neutral country by 2021. The ITCR (Instituto Tecnológico de Costa Rica) School of Forest Engineering, located in Cartago, Costa Rica [also referred to as TEC (Tecnológico de Costa Rica)] has been actively monitoring rainforests to study properties such as water level, biomass growth and meteorological variables, among other things. Researchers have faced severe difficulties accessing remote forest locations for data extraction, and when accessible, valuable resources must be allocated to the manual collection of this data. Project Irazú is a proof of concept which aims to demonstrate a data relay system to transmit daily measurements acquired by ground sensors in remote areas to a data processing center. The project is a joint effort between the ACAE and ITCR. 2)
The Irazú project has two main objectives, which are:
1) To demonstrate the capability to develop and operate an aerospace engineering project in Costa Rica.
2) To develop a scientific mission that will allow Costa Rican scientists to collect data related to the country's rainforests.
Science: The scientific component aims to contribute to ongoing studies to determine the growth of biomass of a tree planting and study the influence of environmental variables. This is important for assessing the environmental services of these ecosystems that fix carbon from the atmosphere. The forest plantations grow evenly, and this condition allows accurate estimates of biomass growth and total carbon fixing. Because the satellite's lifetime will only be 6 months, the scientific team decided to concentrate all their efforts for this mission on the monitoring of growth of tree plantations and to emphasize other aspects, such as to study and understand the hydrology-climate-soil-growth relationships, of the selected species.
This mission will provide the foundation for future development of new proposals on reforestation that offsets carbon emissions. Furthermore, this mission aims to impact directly in the short term the promotion of Costa Rica's forestry sector and to encourage reforestation with commercial timber species.
The general science objective can be formulated in the following fashion: To monitor the environmental service of a forest plantation by carbon sequestration and studying the dynamics of biomass growth and its relationship with environmental variables.
Some background: On March 16, 2016, officials at the Costa Rica-based Central American Association for Aeronautics and Space (ACAE) announced they will launch a crowdfunding campaign to raise $75,000 needed to orbit the first Costa Rican satellite, a small 1U CubeSat. This small device called Irazú, of size 10 cm x 10 cm x 10 cm and a mass of about 1 kg, is expected to be launched to the ISS (International Space Station) and to be deployed into space at some later time from the station. The project takes its name from Costa Rica's highest volcano (Irazú with 3,432 m), located in the province of Cartago. 3)
Project Manager Marco Gómez said, the research consists of real-time measurements of temperature, humidity and carbon dioxide fixation. Data will be collected in a forest in Los Chiles, a mountainous area near Costa Rica's border with Nicaragua, and will be used to evaluate climate change effects on forests.
The Irazú project involves student and faculty involvement from the university; they will be responsible for processing, analyzing and preparing visualizations with daily data obtained at the forest as well as from the satellite mission. Data will be used by researchers from various TEC faculties in projects ranging from climate effects to numerical weather prediction. Information collected will also be shared on a website as open data so it can be used by investigators and students all over the world.
The 1U CubeSat standard was selected for this project since it has been used successfully for various Earth observation missions by universities around the world. Most subsystem were purchased from GomSpace to reduce risk due to their flight heritage.
The spacecraft, features 6 subsystems; the first five (structure, thermal, electrical power system (EPS), onboard computer (OBC) and communication) are essential for any CubeSat mission, while the payload is usually reserved for the scientific component. Since the Irazú project has its scientific component on the ground, the payload was used for educational purposes. A secondary OBC is being developed by Costa Rican engineers to act as an IMU (Inertial Measurement Unit), but mainly to provide these engineers the experience of designing, manufacturing, testing and operating a spacecraft component. One notable absence in the design is an ACS (Attitude Control Subsystem). Since the spacecraft has an antenna with a omnidirectional pattern and since it lacks a scientific payload with pointing requirements, then an ACS is not necessary for spacecraft operations.
The architecture of the CubeSat is presented in Figure 1. It follows a decentralized approach that comes standard in the GomSpace CubeSat platforms. Each subsystem has its own microprocessor that connects to the bus using either I2C or CAN (for the Irazú spacecraft, I2C will be implemented). Additionally, the GomSpace SDK (Software Development Kit) and mission libraries will allow the team to program the spacecraft functions. These will be used in order to ensure rapid development of the subsystems and to lower risk, since they have already been used to successfully develop other GomSpace CubeSats.
Figure 1: Irazú CubeSat architecture (image credit: GomSpace)
The Irazú CubeSat design is similar to the 1U platform offered by GomSpace with the following differences:
• The CubeSat structure is manufactured in Costa Rica.
• The payload is a secondary OBC which acts as an IMU.
• An aluminum plate is placed on one of the sides of the CubeSat and another one inside of the spacecraft for fundraising purposes.
An exploded view of the spacecraft is presented in Figure 2. The GomSpace subsystems were selected since they satisfied all the requirements that were defined in project Irazú's SRR (System Requirements Review). Furthermore, only one supplier was selected for the critical electronic components to facilitate the integration process.
Figure 2: Exploded view of the Irazú CubeSat (image credit: ITCR)
EPS (Electrical Power Subsystem): The EPS consists of 5 solar panels, that can generate up to 2.3 W in LEO, and the power supply, consisting of a 7.4 V battery. The communication system is half-duplex operating in UHF with an omnidirectional canted turnstile antenna. The GomSpace OBC includes an AVR32 MCU and an attitude determination system, consisting of 3-axis magneto resistive sensor and 3-axis gyroscope. The other subsystems included in the spacecraft are thermal and structural. For these, an extensive analysis had to be performed in order to conclude whether the CubeSat will survive the launch and operating environment.
Launch: A launch of the Irazú CubeSat as a secondary payload on a service flight to the ISS is planned for 2018. The launch provider is JAXA.
Orbit: Near-circular orbit, altitude of ~ 400 km, inclination = 51.6º.
Sensor complement: (SOBC)
SOBC (Secondary Onboard Computer)
The SOBC is being built by Imagine XYZ of San José, Costa Rica, a spinoff of the Costa Rica Institute of Technology specializing in electronics research and development. The objective of SOBC is to measure the angular velocity, and linear acceleration of the satellite, as well as the magnetic field surrounding the satellite by implementing integrated arrays of sensors which include: gyroscopes, accelerometers, and magnetometers. This array configuration will generate information that shall be used by an embedded computer to determine and correct noise and drift.
Figure 3: Prototype SOBC mounted on a 3D printed structure (image credit: ITCR)
The ground segment is the final component of the Irazú mission. Its functions are tracking the satellite, monitoring its health, uploading commands and most importantly downloading the data that originated from the forest sensors. The ground station was designed by the Radio Club of Costa Rica, using recommendations from M2 Antenna Systems Inc., which offers solutions for amateur radio satellite ground stations. The main objective was to create a low-cost station for operations in the UHF band. This can be accomplished by using COTS (Commercial off-the-Shelf Components).
The ground station component relates to the actual hardware required to contact the spacecraft, while mission control focuses more on the software needed to operate the mission. The final element of the ground segment is used to turn the raw data acquired by the ground sensors to produce scientific imagery that will be attractive to the public and raise interest in the mission. Figure 4 displays the block diagram of the ground segment.
Table 1 presents the components of the ground station, the selected models for the design and the distributors that sell them. The Radio Club of Costa Rica suggested M2 Inc. as the main distributor since they have purchased and operated their products and have had good experience with this company in terms of delivery and product support. The Yaesu rotator control model was selected due to its ease of use over the one offered by M2 Inc. Furthermore, the Kenwood TS-2000 transceiver was selected since it has a built-in TNC (Terminal Node Controller) and power amplifier, among other features.
Table 1 Stakeholders of the Irazú project
Figure 4: Block diagram of Irazú ground segment (image credit: ITCR)
Figure 5: Irazú project concept of operations (image credit: ITCR)
1) Marco Gómez Jenkins, Julio Calvo Alvarado, Ana Julieta Calvo, Adolfo Chaves Jiménez, j, Johan Carvajal Godíneze, Alfredo Valverde Salazar, Julio Ramirez Molina, Carlos Alvarado Briceño, Arys Carrasquilla Batistai, "Irazú: CubeSat, Mission, Architecture and Development ," Proceedings of the 67th IAC (International Astronautical Congress), Guadalajara, Mexico, Sept. 26-30, 2016, paper: IAC-16-B4,1,8 ,URL available at ResearchGate: https://www.researchgate.net/profile/Julio_Calvo-Alvarado
2) Marco Gómez Jenkins, Julio Calvo Alvarado, Ana Julieta Calvo, Adolfo Chaves Jiménez, Johan Carvajal Godínez, Alfredo Valverde Salazar, Julio Ramirez Molina, Arys Carrasquilla Batista, Luis Diego Monge Solano, "Monitoring of Carbon Fixation in Costa Rican Rainforests through the use of CubeSat Technology," Proceedings of the 11th IAA Symposium on Small Satellites for Earth Observation, Berlin, Germany, April 24-28, 2017, paper: IAA-B11-0906P
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (email@example.com).