A SDR could be cool too, and basically let it connect live to ISS when the GPS confirms its above. CPU and memory might be an issue, but getting some 145Mhz / 4

A SDR could be cool too, and basically let it connect live to ISS when the GPS confirms its above. CPU and memory might be an issue, but getting some 145Mhz / 437Mhz SDR and an external antenna jack on the board could be a cool way of letting the device listen in when the ISS is above.