[dahtguy]

Not necessarily. I've never heard of anyone doing it for space (maybe SpaceX?) but you could have an SDR driving a massive MIMO/beamforming array. The SDR can then dynamically "change the antenna" (change the radiation pattern) with a fixed front-end.

[mng2]

The point is you are limited by the capability you build in at launch, SDR or otherwise. The hardware side is more restrictive than the software side.