There's no subject more fertile for debate than hypothesizing about the nature of extraterrestrial beings.

So, in a study carried out by researchers affiliated with* NASA and Pennsylvania State University ("Would contact with extraterrestrials benefit or harm humanity? A scenario analysis," arXiv:1104.4462v2 [physics.pop-ph]), several intelligent extraterrestrial encounter scenarios are examined. One of the scenarios is a sci-fi favorite: What if we encounter an alien race hell-bent on destroying us?

ANALYSIS: Why Would Aliens Invade?

But this isn't mindless thuggery on behalf of the aliens, and they're not killing us to get at our natural resources; they have a cause. They want to exterminate us for the greater good of the Milky Way.

Yes, they consider us cockroaches. Cockroaches left in charge of increasingly advanced and destructive technology.

Let's face it, with ecosystem destruction on a global scale and greenhouse gases being belched out into the atmosphere at record rates, to a distant alien observer we may look like a destructive civilization spiraling out of control — and they wouldn't be far wrong.

RELATED: The Search for Extraterrestrial Polluters

Therefore, as the ET logic may go, if we're making such a mess of our own backyard, if we venture deeper into space and become a true interstellar civilization, what hope is there that we'll treat the rest of the galaxy (and the other beings in it) with any respect?

WATCH VIDEO: Will the real ET be little green men or little green bacteria?

"A preemptive strike would be particularly likely in the early phases of our expansion because a civilization may become increasingly difficult to destroy as it continues to expand," the study says. "Humanity may just now be entering the period in which its rapid civilizational expansion could be detected by an ETI (extraterrestrial intelligence) because our expansion is changing the composition of the Earth's atmosphere, via greenhouse gas emissions."

Of course, ETI might just be an aggressive race, so like Stephen Hawking's recent warning, the authors of the study suggest that perhaps we shouldn't transmit too much information into space.

The authors explore other scenarios as well, including other destructive outcomes of encountering an alien race. Positive and neutral outcomes are included.

One positive outcome that could arise from bumping into a friendly ETI is that it takes our fledgling race under its wing (tentacle) and helps us, technologically, to push deeper into space. Perhaps the aliens would let us join their Interstellar Rotary Club! They might even join forces with us to repel another, less-friendly alien race — something that could prove advantageous should we find ourselves embedded in a galactic ecosystem.

ANALYSIS: Galactic Ecosystem Survival: Keep Your Head Down

But what of the "neutral" outcomes? What if the ETI is incomprehensible? In that case, they may be too alien for us to communicate with in any meaningful way.

As noted by the Guardian, their entry requirements into a hypothetical Interstellar Rotary Club may be wrapped in bureaucratic red tape, making the whole "alien encounter experience" a bore. Said aliens may even just turn up unannounced, "District 9"-style, and impose on our planet like a friend's sofa. They might be content just eating snacks and watching our TV.

Needless to say, all these scenarios are completely constructed from human experience — any study into the hypothetical nature of ETI will have a heavy anthropocentric bias. What if we encounter an alien civilization whose intentions are completely baffling? What if we can't decide whether their intentions are positive, negative or neutral?

Well, I suppose that's why we need studies like this.

*As noted by a commenter below, this is not NASA research. As in, it wasn't funded by NASA. One of the author's "day jobs" is with NASA, but as noted by Shawn Domagal-Goldman on his blog "Pale Blue": "It was just a fun paper written by a few friends, one of whom happens to have a NASA affiliation."

Obviously this is in response to the huge media interest this work has generated — and possible negative connotations that NASA had directly funded a SETI-like hypothetical study. Still, it's a wonderfully written paper examining the potential "first contact" scenarios with an intelligent alien species. In my books, that's pure awesomejuice.