Gday Skysurfer
I agree that in a catastrophic fail mode, anything can go pearshaped very quickly, but i think we are still looking at the steady state design problems first ( which are quite extreme in this case ).
I like radar as it cant be affected as badly as optical would be by the atmoshpherics. ( Imagine trying to image mechanical semaphores
), but it still needs a motor etc to control it.
I reckon what they need is a fax machine on the orbiter and a hellschreiber unit on the lander.
Loss of bits of data becomes a no issue
.
Andrew