For those curious, I went and looked it up, and the one way (not round trip!) light travel time to the moon is about 1.3 seconds, and one way light travel time

For those curious, I went and looked it up, and the one way (not round trip!) light travel time to the moon is about 1.3 seconds, and one way light travel time to mars is 3-22 minutes or so, depending on how far they are at the time. So maaaaaybe you could have a really painful conversation with someone the moon, but not Mars. edit: This is WITHOUT any latency introduced by the link/protocol, or if you have to then route the message from one side of the earth to the other, just time-of-flight distance calculations, so the absolute minimum possible latency.