When pure evil responds to the Arecibo message, a lowly NASA clerk must convince his superiors that planet Earth is facing doomsday, and nobody cares.

Hi Aidanthedude.
A faceless AN is hard to pull off but can be done.
The force of antagonism, as you probably know, should always be present in order to drive the plot and a physical presence can be substituted by a either a proxy or it's effective power.
A good example is the 'Fifth Element' or 'The Usual Suspect'.

and I guess I only named the Arecibo message...*

Thanks guys, It's all very true.

I'll certainly do some work with this one. You're right, Karel + Nir, the story isn't going to be all about the protagonist trying to convince everybody of the truth, and I guess I only used the named the Arecibo message to keep my word count down, but true. Not everyone knows that stuff and it'd certainly lose a lot of people's interest if they were reading my pitch.

I was originally planning to have my antagonist literally faceless throughout the film, and only be represented via symbolism...Does that count? He was going to talk directly to the protagonist via 'hacked' televisions and other electrical equipment...So many things I can't fit into 25 words. Believe it or not this is meant to be a comedy.

I'll post my updated version of the logline as a reply when I get my shit together. Cheers guys.