SDRs transmitters/transceivers are cheap. Seems like the primary issue would be making your transmitted signal strong enough to actually reach the moon or nearb

SDRs transmitters/transceivers are cheap. Seems like the primary issue would be making your transmitted signal strong enough to actually reach the moon or nearby spacecraft. I'm sure e.g. SpaceX could do a fair bit of meddling if they were feeling so malicious (or unwittingly compromised) though.