Satellite Subsystems

 

Each of the separate systems that form the overall satellite are taken care of by a certain team.  Here is the breakdown:

 

The Power Generation and Distribution (PGD) team provides the power for the CubeSat’s electronic components. Power will be generated with high-efficiency gallium arsenide solar cells, and stored in lithium-ion batteries. The batteries are reserved for usage during the eclipse periods of the satellite orbit (when the satellite passes over the dark side of the Earth), or when the power demand exceeds the output of the solar cells. In addition, a regulation/switching network to provide power to all the CubeSat subsystems is being designed and fabricated by the PGD team, along with a charging circuit for the batteries.

 

The Tracking, Telemetry, and Command (TTC) team is responsible for all satellite communications, on the satellite and on the ground. The satellite transceiver system will be a modified commercial-off-the-shelf (COTS) system, chosen for the short development time that is required. The ground station will also utilize COTS components, in order to shorten the development time enough to meet the strict launch schedule. The communications system will operate in the UHF range, to take advantage of the worldwide network of amateur radio operators that operate in the same frequency range.

 

The Mechanical Structures and Analysis (MSA) team has a twofold task. One responsibility is to determine the temperature gradients throughout the CubeSat. In order to do this, a code for computer simulation is being developed. The thermal conditions of the CubeSat will be simulated using a hybrid resistance-capacitance model (the system is analogous to a resistor-capacitor circuit). Another MSA job is the design and fabrication of all the mechanical support structures needed for the satellite, including vibration and thermal stress simulation and testing.

 

The microprocessors and other digital support circuitry necessary to make the CubeSat operate, as well as all of the software requirements, is taken care of by the Data and Command Handling (DCH) team. Automated tasks will be run by a Rabbit Semiconductors microprocessor. In addition, the TTC and Analog/Digital Sensors teams will have programmable integrated circuits (PIC) chips to aid the Rabbit processors in data routing and handling throughout the satellite. Should the main CPU fail, the PICs can function as back-up processors. The DCH team is also writing the software necessary to run the CubeSat. 

 

Systems Integration and Testing (SIT) is not a subsystem, but is nevertheless an extremely important team.  SIT includes everything that is necessary to ensure that everything on the CubeSat will work as designed. The interfaces and interconnections between subsystems must be well thought out, not to mention component placement, weight, power usage, etc. In addition, the necessary pre-launch testing will be coordinated by this team.