You are in a "No Stopping Zone"
If I had to guess I would say, like me, you are a fan of Douglas Adams.
Read the story now
Your story seems nice and focused to me but I found it a bit lacking in detail. I got a pretty good picture of two of the crew, Capt. Onyango and Lt. Crosby. The other two crew members, not so much. I did get a pretty good picture of the two Concordance admins.
The chronology of Concordance contact with Earth was also a bit confusing to me. Last contact 150 years ago, three missions, sixty years after and they still seem to be collecting information??
You may have also missed an opportunity for some humour with possibly some vague references to Area 51, UFO's, Crop Circles and other Alien Theories..
The parking ticket was a great ending. What about the graffiti though? So many potential laughs there just trying to explain it when they return to earth.
Don't stop now. Keep writing.