The Architecture of the Lucky 7 CubeSat

The Lucky 7 CubeSat is a first private satellite and 7th satellite in the history of the Czech Republic. The project was started as a student project that was funded by private finances. Lucky 7 is 1U CubeSat that integrates several subsystems and sensors.

Power subsystems consist of a Gallium Arsenide solar panels directly charging LiFePO4 accumulators with a capacity of 4 Ah. The satellite uses 3.3 V power distribution bus. The bus integrates 2 A latch-up overcurrent protection circuit.

For improvement of the reliability, the satellite is equipped with two identical sets of onboard computers (OBC), UHF radio modems, and antennas. OBCs are switched by a special watchdog circuit. The watchdog automatically selects optimal configuration.

The instrumentation board integrates the latest version of piNAV GPS L1 receiver, space dosimeter piDOSE, spectrometer, and a low-resolution camera.

The operation and scientific data are stored to FRAM memory of size 2 MB. The memory is logically organized to the 65 536 cells of size 32 Bytes. The data format of each cell is defined in advance, i.e. after reception of the cell, the data can be instantly decoded and interpreted.

For the purpose of the reading of this data by the ground station, a simple single layer communication protocol has been developed that organizes the memory cells to the transmission frames. The protocol enables us to meaningfully operate the satellite even in case of high Packet Error Rate.