OUFTI-1 will be the first satellite to test the use of the D-STAR communication protocol in space. OUFTI-1 will also fly new high-efficiency solar cells provided by AzurSpace.
OUFTI-1 bus provides the necessary support function for the operation of these experiments and is a complex assembly of 7 subsystems listed below. The effective interaction between these subsystems is crucial to the success of the mission. In the framework of OUFTI-1, spacecraft systems engineering is the responsibility of the MIAS: MISSION ANALYSIS team.
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ADCS: ATTITUDE DETERMINATION AND CONTROL
Because the D-STAR telecommunications system does not require the satellite to point in one specific direction, the ADCS subsystem relies on passive magnetic stabilization. This system has been used previously aboard Delfi-C3 CubeSat and will also be used aboard M-Cubed CubeSat. There are several advantages:
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No sensors/actuators required.
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No power consumption.
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Light, safe, and small.
We will use permanent magnets in conjunction with hysteretic materials.
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COM: TELECOMMUNICATIONS
The key, innovative feature of OUFTI-1 is the use of the D-STAR amateur-radio digital-communication protocol. This means of radio-communication will be made available to ham-radio operators worldwide. In the future, it will also be used to control space experiments. Aboard OUFTI-1, it will be considered as a payload and switched on and off for experimental purposes. The telecomands and telemetry will be send to the satellite with the AX.25 amateur radio protocol. In case of the AX.25 system won't work properly a reliable telegraphy beacon should still be functional, in which case any ham-radio operator anywhere in the world will be able to listen to the beacon telemetry, and send it over to us.
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EPS: ELECTRICAL POWER
The EPS subsystem generates, stores and distributes electrical energy to the on-board subsystems throughout the mission. Power is generated using triple-junction GaAs solar cells and stored using Lithium polymer batteries.
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MECH: MECHANISMS
Antennas will be folded during launch and have to be deployed once in-orbit. The role of the MECH subsystem is to design the retaining and deployment mechanisms. The retaining mechanism will hold the antennas in place during launch operation. The deployment mechanism will allow a reliable deployment of the antennas.
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OBC: ON-BOARD COMPUTER
The OBC subsystem controls data flow on board the spacecraft. Its main tasks involve supervision of OUFTI-1 operation, telemetry data formatting and storage, telecommand data decoding and management. It must also provide a time reference. The central microcontroller is the one provided in the Pumpkin's CubeSat kit (FM430 flight module with Texas Instruments single-chip 16-bit MSP430).
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STRU: STRUCTURE AND CONFIGURATION
Pumpkin's CubeSat kit was bought in April 2008 (see gallery). It comprises the main structure together with the FM430 flight module. Finite element simulations of OUFTI-1 response to various launch loads are currently carried out to ensure its structural integrity. These simulations are performed using the commercial finite element software SAMCEF. Experimental verification using an electrodynamic shaker is also envisioned.
The spacecraft configuration is achieved using CATIA software. The objective is to position the different satellite components in an optimal manner (temperature and radiations issues) and within the available volume. Constraints on the location of the center of mass specified by the cubesat design specifications must also be fulfilled.
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THER: THERMAL CONTROL
The thermal subsystem is quasi-fully passive. Thermal control is mainly achieved using carefully selected surface finishes and appropriate configuration. The batteries need a dedicated thermal control system, which is composed of one heater and two thermostats for each of the two batteries. Thermal design verification is carried out using ESATAN-ESARAD softwares to ensure that all satellite components function within the prescribed temperature range. Experimental verification in the vacuum chambers of Centre Spatial de Liege is also envisioned.
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xEPS: EXPERIMENTAL POWER SYSTEM
Another experiment that was develop in the framework of OUFTI-1 is an innovative electrical power system proposed by Thales Alenia Space ETCA. Due to time constraints, this experiment is postponed to the next CubeSat of the university.