"Would Contact with Extraterrestrials Benefit or Harm Humanity? A Scenario Analysis" A scholarly paper (33-page pdf) summarized by the Guarniad with its most attention-getting scenario semi-explained by DiscoveryNews: "[the aliens may] want to exterminate us for the greater good of the Milky Way." (for the record, it was NOT written for NASA though one of the authors is a "NASA dude")
posted by oneswellfoop on Aug 19, 2011 - 72 comments

How to talk to an alien, a detailed guide to first contact. You might want to invent your own language for just such an occasion. Or just get to know the most common patterns for fictional alien languages.(previously)
posted by Wrinkled Stumpskin on Jul 21, 2011 - 47 comments

Today is the day that extraterrestrials make contact with Earth! According to a retired NORAD officer who has studied alien phenomenon since WW2, a fleet of UFOs will perform a massive display for hours over the world's principal cities today, the first step in mankind's acceptance of alien existence. Drawing upon his military experience and a wealth of historical data from NORAD intelligence, Stanley Fulham has concluded in his recently published book, Challenges of Change, that October 13, 2010 is the date of first contact. Although they won't land or communicate today (so as not to cause a worldwide panic), the aliens come with the benevolent intention of saving humans from ecological disaster. Hoopy froods should know where their towels are.
posted by johnnyace on Oct 13, 2010 - 188 comments

Lets say you're the first human ever to make alien contact... (via)
posted by fearfulsymmetry on Apr 9, 2010 - 100 comments