The nano- and pico-satellite programs carried out in our University are driven by educational and scientific purposes, and they involve students and researchers from several engineering areas among which Aerospace, Mechanics, Electronics, Physics and others. These programs are usually conducted in collaboration with other universities and/or space agencies, and with the support of local and international space companies.
As Figure 1 illustrates, a space mission carried out by an University is driven first of all by the relevance that the mission has both for the research and the education purposes, being at the same time constrained by limited budget and resources.
To educate aerospace-engineering students on systems development, management, and team work.
To achieve insight in the development of scenarios and enabling technologies for future space missions
The main program guidelines have been assumed as high level objectives and constraints for the [email protected] program. They can be listed as follows:
- WHAT/1: To inspire and prepare future space-professionals: students are the end users of the mission
- WHAT/2: To improve knowledge in space science and engineering: real world shall take advantages of our missions
- WHY: To meet stakeholders’ needs. Stakeholders are: students & civil society, scientific community,industry
- HOW: To carry out a space program from the design to in-orbit operations, completely managed by students
As the program shall have educational relevance, students must learn how to build a space mission from the very beginning throughout the project development, dealing with all the aspects related to a space program. The project is carried out by the student CubeSat Team, which is coordinated by the Team Leader, who is responsible for the whole program. The team is organized according to a defined work breakdown structure, which takes into account both technical and non-technical aspects. Students learn by practice how to:
- design, manufacture, verify and test, and operate a space system
- manage, control and document the development process according to current regulations and applicable standards
- prepare technical documentation to report the project
- team working and collaborate in an international multicultural environment
- disseminate the results of the program
- promote the program within the suitable stakeholders
The Mission Objectives (MO) represent the broad goals which the system must achieve to be effective, productive, efficient and useful. In our case the system is a CubeSat-class satellite, developed by university students. The motivations that led us to the definition of the mission objectives are therefore to be found within the university setting, and include “needs” of both scientific-technological importance as well as educational significance.
At the present moment, we are experiencing a “big” revolution in CubeSat Community because a great interest in this kind of space platforms is growing also among actors other than universities. For few years after their invention, CubeSats have been developed exclusively within the academia for higher education purposes with possible technological and scientific secondary objectives. We can now say that nowadays the interest in CubeSat missions for scientific or commercial services is growing steadily and CubeSats are thus evolving from pure university education tools to spacecraft buses for scientific and commercial payloads.
Notwithstanding the necessity of keeping cost down and taking into account the educational purpose of the CubeSat program, our CubeSat missions also have scientific and/or technological objectives, which reflect real interests of the scientific and industrial communities.
One of the most significant challenges is how to accomplish science goals while facing severe limitations on mass, volume and power. On the other hand, one of the benefits of CubeSats is the relatively low cost from standardized components and piggy-back launch opportunities. To accomplish more ambitious scientific goals, a certain set of technological challenges need to be addressed. We strongly believe that CubeSats can contribute to broad science goals, if supported by the appropriate set of technologies.
The capability of autonomous attitude determination and control is one of the enabling technologies for future CubeSat missions, specifically where requirements in terms of stabilization and pointing accuracy are critical to the effectiveness of experiments, payload operations, communications, and in turn to the mission success. More than 100 CubeSats have been launched since year 2003, about 45% of them hosting an Active Attitude Determination and Control System (A-ADCS) on-board . The remaining part includes either satellites with no actuation or with passive control systems, the latter often providing only few pointing options, weak accuracy and very limited attitude maneuverability.
The will to keep on focusing on attitude control systems and the purpose to enhance A-ADCS capabilities for CubeSats has been well supported by the attention and the curiosity of the students in our university. Moreover, the scientific community and the industry have proved to be interested in this topic in several occasions. For these reasons the primary scientific objectives of [email protected] mission is:
- to demonstrate the capability of autonomous determination, control and manoeuver, through the development and test in orbit of an A-ADCS entirely designed and manufactured by students.
To this purpose, the integrated A-ADCS system, including the electronic board, the software and the set of magnetic actuators, is considered the primary payload of [email protected]
The secondary objectives are driven by the necessity to develop custom solutions to support the spacecraft bus, for telecommunication, commands, data handling, both on-board the satellite and on ground. Testing in orbit COTS technology and in-house developed hardware and software will demonstrate the students’ skills and capabilities. Therefore the secondary objectives read as follows:
The secondary objective, but not least important, concerns the possibility of:
- to develop and test in orbit an on-board UHF communication system (electronics and antenna), entirely designed and manufactured by students
- to develop and test in orbit software for on-board command and data handling, entirely designed and implemented by students
- to develop a ground facility for telecommunication in amateur band, including the design and implementation of necessary hardware and software
- to design, assemble and integrate high-efficiency solar panels, to be tested in orbit for future applications
- to design, manufacture and test structure and mechanisms to support the spacecraft bus.
It describes both the usefulness and efficiency attributes of the mission. The former relies on the educational aspect, as well as on the possibility given to the team to enhance its knowledge and experience. Under a different perspective, the mission can be seen as a test-bed for components, as well as an opportunity to perform reliability studies. The latter, efficiency, refers to the capability to develop a complex system with few resources. It is mainly related to the university low budget constraints, but it turns into an opportunity for bearing in mind cost reduction and simplicity at any level of the engineering process.
The motivations, needs and constraints that led to the definition of the mission objectives are shown schematically in Figure 2: