Our Satellite
Here we will explain the individual parts of our satellite. This includes our goals, sensors, components, circuit board design, changes and ultimately its construction.
Here is our final report (8,5 MB) from the German CanSat competition.
Note: The final report is only available in German.
The pre-launch report for the european CanSat competition is available here (16,8 MB).
Our Mission Goals
We have set ourselves three main goals for the CanSat competition:
Firstly, we intend to enable communication between two satellites by building a simulated satellite on the ground (in the form of a ground station) and sending data to the satellite. This data should then be sent back to our ground station. More details are provided in the section titled “Missions”.
Secondly we want to achieve a higher position accuracy through the orientation and acceleration sensor.
Furthermore, we aim to build our satellite as fault-tolerant and robustly as possible. Therefore, it is important to avoid complexity. In order to achieve this fault-tolerant system, we will use an SD card to store all of the data: not only in the primary module, but also in the secondary module, and also to install a second battery in order to supply both modules with power if one of the two batteries fails. In order to avoid errors and faults in the individual modules, we will do without cables in most instances.
The primary module must be stable enough so that it can be reused. In order to prevent any unnecessary contact between the circuit boards, we will place all of the components on a single circuit board.
Our third goal is to create the modularity that our satellite should have. For this purpose, the primary module should be reusable and the secondary module should be interchangeable, so that several missions can be carried out with a single, and the same, satellite.
The Sensors
Sensor system:
In order to avoid different voltage levels and to save space, we have decided to power the whole sensor system with 3.3 volts. In addition, we have thought about connecting most of the sensors with one bus (in this case I²C) to the microcontroller. This limited our options considerably.
Our sensors and components:
Sensor | Name | Interface |
Air pressure | I²C | |
Temperature | I²C | |
Position and accleration | I²C | |
GPS | GPS UBLOX NEO M8 | UART |
SD cardwriter | CONN Micro SD CARD | UART |
Buzzer | GPIO | |
Microprozessor |
The SD cardwriter, which stores all of the data that we receive (including from the sensors), is installed on the primary and the secondary module. That means that when the microcontroller requests data from the sensors, it is recorded directly on the SD card on the primary as well as the secondary module so that we have a certain level of redundancy.
In addition to that we use a small buzzer to easily locate the satellite after the landing.
We want to use the STM32F413 micro-controller for our CanSat. This chip has enough ports to connect our sensors. Since the chip runs on 100MHz we can run all our calculations without any problems.