Beside their use in the in-situ determination of upper atmospheric density these satellites also function as technology demonstrators and as amateur radio digipeaters. Each satellite can be accessed via amateur radio using the APRS protocol. Part of the technology demonstration was the integration of a command and telemetry system that would not require the use of normal antennas that would destroy the spherical shape of the micro satellites. The MAA sphere communicates by electrically isolating its two hemispheres with an insulating center disk. The FCAL sphere actually does deploy four whip antennas but each antenna is only a few thousandths of an inch in diameter.