Saturday, June 27, 2015

The Puzzlement of Discovery

The defining exclamation of scientific discovery isn't "Eureka!"

Sometimes it works out that way. "Eureka" -- from Greek meaning, more or less, "I have found it" -- is supposedly what Archimedes exclaimed upon realizing, while sliding into his bath, that displaced water may be used to measure the volume of a solid object. He'd been having a dispute with a goldsmith, you see, and suspected he'd been cheated. He needed to find a way to prove it, and a solution presented itself to him.

"Eureka" moments are far more common in engineering than in science, actually. Inspiration for the solution for technical problems tends to strike at the weirdest moments. I've had them at the gym, in the shower, and while walking across the street to a convenience store.

But moments of true discovery? Those aren't marked with glad shouts. Those are more often marked with puzzled murmurs. Not so much "Eureka!" as "What the heck did we just see?"

We're seeing one of those unfold in real time. Dawn is settling down into its science/mapping orbit around Ceres. And Ceres is proving to be a very puzzling place.

The $100,000 Question here is: What are those shiny bits? No one really knows for sure. The closer we get, the better and clearer the pictures are, but so far that hasn't brought any real clarity. One article I read compared them to Las Vegas at night, as seen from space. No one takes that interpretation seriously, mainly because Ceres is a damned odd place for ET to build a casino.

There's no real proof yet, but most people have a sneaking suspicion that what we're looking at are ice sheets. And not just those two bright spots, they're starting to show up all over Ceres' surface. Which may mean ...

... that there's just a thin layer of dusty rock on top of a thick layer of ice.

If that's the case ... this is a find of unimaginable value. Gold in them thar hills? Feh. Don't bother me with such penny-ante stuff. Water is important.

If humanity is to have a future away from Earth, we'll have to find somewhere to get water. Beyond the obvious, water can be electrolyzed into hydrogen and oxygen. We need the oxygen to breathe, the water to drink, the hydrogen can provide power via fusion (once we figure out how to do that), and hydrogen and oxygen together can be used as rocket fuel ... or, the water itself can be used as the working fluid for a nuclear thermal rocket. But all this hinges on finding a place to get water that isn't prohibitively expensive.

Water is abundant here on Earth. But you have to lift that out of Earth's gravity well, boosting it ten kilometers per second to punch through the atmosphere, up to altitude, and then up to orbital speed. Then you have to boost it from low Earth orbit to wherever it is you need to use it.

Incidentally, this is why the movie Elysium never made any sense to me. Anyone with the technical savvy to build an orbital habitat would know better than to get their routine supplies from down here. The delta-V costs will simply eat you alive. But I digress...

Or maybe I don't? Because the problem is, if you can't get water from Earth, where do you get it?

Well, lots of places. Jupiter and Saturn have plenty of icy moons. Europa, Ganymede, Enceladus, and each of those have about as much water as Earth does, in the form of ice. The problem is, though, you have to lift that ice out of either Jupiter's or Saturn's gravity well, and that ain't exactly cheap. You're better off doing that than lifting it from Earth's surface, but not by a tremendous amount.

Ceres, now... In terms of delta-V, getting to and from Ceres isn't that hard. It takes a long time, but doesn't take much fuel. Remember that Dawn flew from Vesta to Ceres on about a fistful of rocket fuel. And fuel is the long pole in this particular tent. An enormous ice supply, located in the middle of the Asteroid Belt, is a Godsend for would-be colonists. It makes a ludicrous fantasy into ... well, still a very difficult enterprise, but at least one that's within shouting distance of feasible.

Or, it could all be smoke and mirrors. Something else entirely. Soon, we'll know for sure, one way or another.

No comments: