I'm trying to remember the name of the short story, or TV episode, where the plot is that it's set at a mission control centre on Earth somewhere, and they are awaiting the signal from a probe which has been sent to a world outside our solar system.
The twist of it is that one of the people there is an alien from that world; they saw the probe, and destroyed it and came looking for us after they realised it wasn't hostile, and are offering to swap their FTL technology for our probe technology if the signal is received etc.
Any ideas what this was?