Australia started with a very big bang?

ScienceDaily: Big Bang In Antarctica: Killer Crater Found Under Ice

Today's interesting science news is about evidence found for a very big and very old giant crater beneath the ice of Antarctica:

The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years -- the time of the Permian-Triassic extinction, when almost all animal life on Earth died out.

Its size and location -- in the Wilkes Land region of East Antarctica, south of Australia -- also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward.

Wouldn't be much concern about global warming - or anything else for that matter, if a hit that size happened again.

Now I'll wander off into science fiction speculation for a bit. One of the reasons for colonizing the solar system, if you actually like humanity and think it deserves surviving, is to provide a lifeboat for civilization if a huge global disaster of that kind happened again. (Maybe there is little chance of killing all people on earth, but the course of civilization would surely be put back a couple of thousand years.)

Now, the easiest (and nearest) place to colonize is the moon. But, there is one significant problem: what will happen to the human body after living for prolonged periods in 1/6 G, and what will the bodies of babies conceived and born in such a low gravity environment be like? Long and spindly like that silly Jedi knight in the last couple of Star Wars films? Or same body shape, but with a heart that simply could never cope with a full 1 G? (It would presumably be the same as a normal "1 G" person being taken to a 6 G planet to live.) Can you counteract the effect of low gravity by sitting in a centrifuge for an hour a day?

One of the first things a permanent moon colony should investigate is animal models of this. Rats, rabbits or other animals that breed quickly should be put through a few generations of low gravity to see what happens to their bodies. I think Jerry Pournelle has written that rats have been put in a permanent higher G environment (in a centrifuge) and developed super muscles to compensate. However, I don't know that it is possible to simulate a 1/6 G for a rat for any long period of time.

If it all looks hopeless (from the point of view of humans born there never being able to go back to earth) then it may be some time before any woman ever lets a child conceived there be born.

The other space colonisation idea is the construction of giant spinning O'Neill colonies, which could have an artifical gravity somewhat higher than the moon. (Living in about 1/2 G sounds a pleasant idea to me.) Such huge engineering seems to be no longer taken seriously, but who knows, in a hundred years it may be on the cards.

As for Mars: well, it has water, but then it seems quite possible that parts of the Moon do too. Its atmosphere is so thin it's barely worth having there at all. And its gravity is only about double that of the Moon, but is that enough to make it safe to have a baby there (who can return to earth?)

(I just found a site for a proposed "Mars Gravity Biosatellite", which would send 15 mice into space in a spinning satellite designed to simulate Mars gravity. I am not sure if this will involve them having babies, though.)

Anyway, Mars is so far away that I am sceptical of its use as a lifeboat for humanity. Building a big enough colony underground on the Moon, near lunar ice, seems a much better way to go to me.