in order for the satellite to be useful, it will need to be able to transmit and receive data. Other small sats have shown that a 100mw low cost radio module is all that is needed to communicate from space. As my power budget is extremely limited, I need not only a radio that will fit in the 20x20mm PCBs, but be power efficient.
The smallest 433mhz module is about 16x16mm. But even though this is tiny, the tinyduino sized boards don't leave enough room to solder one of these. This means that a custom radio board is required.
I'm going to use a Semtech SX1278 transceiver IC, in order to use the LORA modulation method. The receive sensitivity of this module is way better the the other small modules on the market. Plus, I need to make up for the losses I'll incur by using a tiny PCB mounted antenna.
Here's the almost complete power supply board: