Kochi counts down to launch of 'space sake'

KOCHI -- The world's first sake made from yeast that has traveled into space will be put on sale from April.

An association of sake breweries in Kochi Prefecture hit upon the idea of using space-traveled yeast in an attempt to invigorate the local sake industry.

Breweries put yeast produced in Kochi Prefecture aboard Russia's Soyuz rocket in the autumn last year. The yeast was then returned to them after the 10-day journey in space.

Using the space-traveled yeast, Kochi Prefecture breweries have produced 17 kinds of "space sake." (Mainichi)

The title of the article, "Super-powerful new ion engine revealed", is a little misleading. The first line of the article corrects the error by explaining that the new engine is ten times more efficient. For the non-rocket-scientist types out there, that's kinda like a new gasoline engine getting 10 times the milage, not ten times the horsepower.

The new engine is kinda cool as far as it goes, but they neglect to mention two little drawbacks of ion engines - electrical power requirements to perform the ionization, and the incredibly tiny thrust levels.

The kicker statement can be found in the second paragraph from the very end of the article, which manages to include both drawbacks in passing:

"Given sufficient electrical power, a cluster of DS4G engines could take a crew to Mars and back, says ESA."

First, the "Given sufficient electrical power" part. Back in the early 80's, a rather advanced ion engine required approximately 13,000 volts to operate. Working with a conservative value of 10 watts of power per square foot of solar array, you end up needing solar panels rivaling the size of the Mojave Desert to power the engine. OK, so that's a bit of an exaggeration, but they'd still be really, really big. And they'd only be useful close-in, like the afore-mentioned trip to Mars. Outward Bound, their efficiency would drop pretty rapidly as they moved away from the sun. You'd need to go nuclear in a big way to produce the necessary power over the required length of time (realistically, you'd want to do that for a Mars trip too, but nuclear powered spacecraft aren't exactly PC these days).

The second part, "...a cluster of DS4G engines..." is necessary due to the incredibly low thrust of ion engines.

Useful space engine thrust is not just about how fast you toss stuff off the back of the truck, but also about how much stuff you toss off. And ions, no matter how fast you toss 'em off, are really, really tiny, and only get tossed off one at a time. Therefore, the "cluster" of engines part.

Even with clustered engines though, the total thrust would be so low (less than one (1) pound of thrust), as to be useless for getting off the planet. When used in space however, they can accelerate a spacecraft continuously for months (or even years), allowing it to reach truly righteous velocities. Just so long as you remember to start decelerating it at the halfway point to it's destination, 'cause it will take it just as long to get slowed down as it did to get it up to speed in the first place. After all, zipping by your intended destination at a measurable (if small) percentage of the speed of light isn't really useful.

Still, 10 times the efficiency is pretty neat, even if it isn't ten times the thrust. Here's hoping they get it working in my lifetime.

". . . Aerospace employment has dropped 106,000, or by 13 percent since September 11, 2001, and it has fallen by nearly half, or 642,000 since December 1989, a period that marks the end of the Cold War."

(emphasis mine)

. . . or do we?