I think, the mission cannot be won in the 2nd round since the mission status for 'Mission Accomplished' says
GD Storybook p. 28 wrote:
There are no aliens AND no Alien Signals in play at the end of the mission.
I guess that means, you have to play up to the 12th event.
Otherwise you could also win mission 5 in round 1 before doing anything, couldn't you? And if I'm reading it right, you just partially accomplished the mission, because there should have been some more signals in play?
I also assumed that the Scanning Rule 'replace the scanned Alien Signal with the Xeno-Alpha' is applied everytime an agent is scanning successfully. So the Alpha returns over and over again.
I could be wrong anyway?!