Has to be able to decrypt 56 bit key DES

Has to have a "safe" mode

Have time tagged commands

Store time tagged commands for 3 days

Have a 2 stage command process (Have two commands needed to do a single critical thing)

Record 4 points of telemetry once a minute (So must be woken every minute, do some activity, and then sleep)

Be able to, when needed (likely once every few minutes to every 15 min), do an exact calculation of position and orientation from sensors.

Have an accurate clock on board

Downlink telemetry within 12 hours

Process and return a full image within 90 seconds of taking it using a 9600 bps connection or even 1200 bps

Run a high intensity system for around 4 min during a pass, both camera and comms