Story summary.An unmanned human starship was sent out to flyby Alpha Centauri system, change direction using gravity of one of its stars, & then go on to Gliese 581. This in a world that considers anything without obvious payoff as waste, so the project had major opposition.
Now, many decades later, the ship has reached the Alpha system, but things don't seem to be going as planned. There seems to be actual sabotage to the project...
Notes."Firewall" of title is the name of the "shield" of the starship. "The door" is a metaphor: the man who's not capable enough to do great deeds himself, but performs a great service by opening & keeping open the door for others who're capable.
Fact sheet.First published: Analog, March 2013.
Rating: B.Related: Stories of Sean McMullen.