http://hanson.gmu.edu/greatfilter.html

If it is one of our past steps, such as the development of single-cell life, then we shouldn't expect to see such independently evolved life anywhere within billions of light years from us. But if it is a step between here and a choice to explode that is very improbable, we should fear for our future. At the very least, our potential would have to be much less than it seems. Optimism (as defined here) regarding our future is directly pitted against optimism regarding the ease of previous evolutionary steps. To the extent those successes were easy, our future failure to explode is almost certain.

Essentially if you define the steps along the path to societal explosive growth towards galactic colonization to be something like:

1. The right star system (including organics)
2. Reproductive something (e.g. RNA)
3. Simple (prokaryotic) single-cell life
4. Complex (archaeatic & eukaryotic) single-cell life
5. Sexual reproduction
6. Multi-cell life
7. Tool-using animals with big brains
8. Where we are now
9. Colonization explosion

And you take into consideration the fact that we see no evidence in the Galaxy for an existing galactic civilization, then something along the path from 1-9 is a Great Filter.  Something is blocking the creation of galactic civilizations.

From this it follows that if the steps 1-7 are easy, then the jump to step 9 must be very very hard.  The reverse of course follows.  The Great Filter may already be behind us and now we have smooth sailing.

My bet is that the Great Filter is in front of us.

And then, why then my dear travelers through this universe of ours, we will have the mind blowing space traveling abilities of the far future.  I speak of the awe inspiring year of 2001.

At least that's how science fiction predicted it.  Funny we're still driving combustion engine cars and the grand total of people who have been in space is still less than 1 thousand.  (I guess that is a lot more than 1, but it is still less than a billion).

Self-sufficient space habitat designed

Now we hear about a "new" set of technologies being refined down under in Oz. [linky]

Devised by an international team of 30 space scientists, Luna Gaia would be a 'closed-loop' environment, meaning that almost all material within the system is recycled with very little need for input from outside sources. The current design caters for a team of 12 astronauts under isolation for up to three years.

This doesn't sound Earth shattering except it is a skill set that we do need to have fully understood before we can successfully deploy a space colony. Shipping up a couple of cases of macaroni and cheese gets a bit prohibitive at thousands of dollars per pound of payload.

A lunar base is unlikely to ever be 100 per cent self-sufficient, said Chartres, because no atmosphere is completely safe from leaks and it could not provide humans with all the nutrients that they need to survive.

Luna Gaia...ugh.  Why not call it Lunar Colony Test Facility?