Thursday, June 15, 2006

Space Colonies Needed - Stephen Hawking

Ah hah! Now, instead of nurturing my own deluded fantasies about eventually moving to my retirement property somewhere in the Asteroid Belt, I get to claim some authority!
The survival of the human race depends on its ability to find new homes elsewhere in the universe because there's an increasing risk that a disaster will destroy Earth, world-renowned physicist Stephen Hawking said Tuesday.

Humans could have a permanent base on the moon in 20 years and a colony on Mars in the next 40 years, the British scientist told a news conference.

"We won't find anywhere as nice as Earth unless we go to another star system," added Hawking, who came to Hong Kong to a rock star's welcome Monday. Tickets for his lecture Wednesday were sold out.
See that? DID YOU SEE THAT??!!! Now Hawking - IQ, like, a billion - is on my side, bitches!

As it turns out, those crazy astronomers have also found a new trove of asteroids, this time at the leading trojan point in Neptune's orbit.
A newly discovered asteroid in Neptune's orbit indicates the existence of a much larger, but as-yet-unseen, cloud of rocks in that region. The asteroids in Neptune's orbit might even outnumber those in the main asteroid belt between Mars and Jupiter, the new research suggests.

The asteroid was discovered by Scott Sheppard of the Carnegie Institution of Washington, and Chadwick Trujillo of the Gemini Observatory in Hawaii, both in the US. They used Carnegie's Magellan-Baade 6.5-metre telescope in Chile and the 8.2-metre Gemini Telescope.

It is one of four known Neptunian "Trojan" asteroids, which orbit in lockstep with the planet. Two of the Trojans were discovered by Sheppard and Trujillo in 2004 and 2005.
Now, obviously this isn't something we're going to go out and grab tomorrow. In fact, "go out and grab" is the wrong paradigm altogether. Far better to use it where it is. And why, pray tell, would we want to do anything out around Neptune's orbit? It just so happens that Neptune's combination of smallish size and being a gas giant makes it a fair bet for retrieving Helium-3 and deuterium (or at least, a better candidate than all the others.)

Of course, if these Neptunian trojans follow the patterns of the Jovian ones, then that means they're far apart. Really far apart. The sheer size of the solar system means that the Trojan "points" ahead and behind Jupiter really amount to a volume greater than the solar system inside Mars' orbit. If anything, Neptune's would be even further apart.

Before anybody bothers, no, we have nothing that could conceivably move large numbers of people off-planet. Hell, it looks like space elevators may even be a bust, and they were the best hope up to this point. From Nature, behind their paywall:
Is it possible to make a cable for a space elevator out of carbon nanotubes? Not anytime soon, if ever, says Nicola Pugno of the Polytechnic of Turin, Italy. Pugno's calculations show that inevitable defects in the nanotubes mean that such a cable simply wouldn't be strong enough.

The idea of a space elevator was popularized in science fiction, where writers envisioned a 100,000-kilometre-long cable stretching straight up from the Earth's surface and fixed in a geosynchronous orbit. Payloads, or tourists, would simply ascend the cable into low-Earth orbit, eliminating the need for rocket launches....

Researchers think that the best shape for a space-elevator cable would be a ribbon, about a metre wide and as thin as paper. It would need to withstand at least 62 gigapascals (GPa) of tension. That's about as much as in the rope of a tug-of-war with more than 100,000 people on each side.

Laboratory tests have shown that individual nanotubes can withstand an average of about 100 GPa, an unusual strength that comes courtesy of their crystalline structure. But if a nanotube is missing just one carbon atom, this can reduce its strength by as much as 30%. And a bulk material made from such tubes is even weaker. Most fibres made from nanotubes have so far had a strength much lower than 1 GPa.
So what are we left with? Well, we might have to go back to the future (I couldn't resist): If we can't use elevators, then we'd better hope that materials science can make lighter, stronger materials that can withstand orbital launches. If we crack that, it might be possible to fulfill the idea originally behind the space shuttle - reusable launch vehicles capable of a 7-day turnaround. (No, SpaceShipOne isn't it. Yet.) If we can get something that works more like a 777, then moving large numbers of people off-planet becomes a much easier proposition. And there's no shortage of space, either.

The final option is that space settlement is something that's forever impossible, but that's a depressing eventuality I'd rather not contemplate.


Ronald Brak said...

I'm afraid a space elevator wouldn't be practical even if we could make a cable without defects. The tension the cable would be under means that the slighest damage from a dust particle or space junk would cause the cable to snap and bring the whole thing down.

But cheer up. Even if the costs of space travel never go down, people will still be able to afford to go into space in the future as people become richer. At the moment the average person in the U.S. would have to save at least 10 salery to afford a trip into orbit. But if we can avoid killing ourselves and manage a 3% economic growth rate per person, then in 100 years an orbital trip would only cost about seven month's pay. In two hundred years it would only be about two weeks pay. If you are one of these people who think growth rates are going to increase due to technological development then the day that you'll be able to travel to mars on a month's salery will be here even sooner.

Battlepanda said...

I really don't understand. I know we're messing up earth, but surely it is still a long while off from being as inhospitable as, say, Mars. As for space stations, I bet long before that becomes practical for more than the tiniest sliver of the population, there will be massive biodomes built right here on earth that are like pockets of livability among the increasingly contaminated planet.