My policy of sponsoring realistic space art to spawn realistic space economics may be bearing some fruit. I sponsored this picture from David Robinson first published in September. In January, Aerospace America had this to say:

"Picture a buggy pulled behind a rover that is outfitted with a set of magnetrons," [Larry Taylor, distinguished professor of planetary sciences at the University of Tennessee] suggests. (A magnetron is the heating element in a microwave oven.) "With the right power and microwave frequency, an astronaut could drive along, sintering the soil as he goes, making continuous brick..."

The U.S. withdrew from the ABM treaty. Is withdrawing from the Outer Space Treaty in the cards? One of the big selling points of the 1967 outer space treaty was the return of off course astronauts. Now that China and Russia are much more open, that really isn't a point any more. I would think that some device that would grant title to a certain hectarage after a certain amount of development would be best. What would your "Territorial Ownership Treaty" look like?

Rod: it would be an auction kind of like the de-sovietization of the Czech Republic where everyone gets a share of the proceeds. http://www.thespacereview.com/article/224/1

If sintering roads to make bricks was such a good idea,
wouldn't it be done now on earth?

"If sintering roads to make bricks was such a good idea,
wouldn't it be done now on earth?"

Earth has weather and a freeze thaw cycle. Not to mention our vehicles are much bigger and 6 times heavier for the same mass.

Ever heard of cinder blocks?

"If sintering roads to make bricks was such a good idea, wouldn't it be done now on earth?"

As per the Aerospace America article, the effective bulk resistivity of the lunar regolith makes it a fearsomely good microwave absorber, melting before tea boils in a conventional microwave.

Not sure about terrestrial soil - if I get time in a couple of months I may throw some in our resonant cav1ty in the lab to see what happens. If the resistivity is too high it'll need a huge field to heat up; too low and it will reflect the microwaves rather than absorb them.

Note this result from experiments on lunar regolith simulant:

http://ares.jsc.nasa.gov/HumanExplore/Exploration/EXLibrary/DOCS/EIC049.HTML

Controlled, even sintering of rock powder by direct microwave heating proved impossible, due to the combined effects of thermal runaway (Kenkre et al., 1991) and self-insulation. The microwave coupling efficiencies of the minerals in MLS-1 rise dramatically with sample temperature. As a result initial heating is slow, but becomes increasingly rapid at temperatures above approximately 400 C. Microwaves penetrate the sample, and heating occurs throughout its volume. However, the center is well insulated by surrounding material, and heats faster than the outside. Typically, our samples sintered strongly or melted in the centers but remained unsintered on the edges.

Paul, last July at the Space Frontier Moon conference in Las Vegas, one of the presentations was about how current lunar regolith simulants were of the WRONG composition, in at least one critical respect. The difference was said to be nano-phase iron created (deposited?) from countless high velocity asteroid impacts. Larry Taylor made the report.

Yup, you can microwave JSC-1 forever and nothing very interesting happens.

But Taylor snagged a small sample of real Apollo lunar regolith and guess what? It absorbs microwaves like a champ, heats nicely and sinters readily.

The difference? Lots and lots of nano-phase iron particles created by high velocity impacts.

One link I snagged fast. There are many more.

That's good to know. Thanks.

One other interesting thing in that paper I referenced was the observation that you can simultaneously sinter and extract oxygen, if you sinter in H2 gas (this would also tend to even out the heating due to heat transport in the gas). They converted about 10% of the brick to metallic iron by FeO + H2 --> Fe + H2O (and similar on Fe(III) ions). So bricks could be a low-cost byproduct of O2 extraction.

Getting stuff done on the moon just seems to be getting easier and easier. Taylor was a hoot to listen to in person, with his "aw shucks, I like to microwave unusual things" presentation.

As I recall (may be wrong) he didn't tell anyone he intended to microwave the Apollo lunar sample because he knew he'd be told, "Don't bother"

= = =

Now take that metallic iron you mention, add CO to make carbonyl gas and you can work with the iron in lots of other cool ways. Cast metallic iron igloos thick enough to hold an atmosphere?

But google tells me nickel carbonyl is easier to work with. And for that we may need to find an intact chuck of Ni-Fe asteroid (same place as PGM). Find metallic nickel, convert to carbonyl gas and then vapor deposit and we can fashion plenty of intricate parts right on the lunar surface without enormous infrastructure.

Or you could crash a metallic asteroid into the Moon... although that sounds far too much like a movie shown on MST3K some time back.

Or you could crash a metallic asteroid into the Moon... although that sounds far too much like a movie shown on MST3K some time back.

One obstacle to mining asteroids in free space is the fact that many of them are spinning along multiple axes. Some are spinning pretty darn fast. Kinda difficult to begin work that way.

Now, if an asteroid smacked down on the moon, it would stop spinning. ;-)

And, if it did not pulverize into a gadzillion tiny pieces too small to find, you could collect the pieces and process them. But, if these asteroids do not get smashed into pieces too small to find, there should be plenty on the moon already, or so it would seem.

Actually, what it sounds like to me is,

Smash ASTEROIDS into the MOON in ORDER to better MINE them!

WIDESPREAD DISTRIBUTION AND DISSEMULATION OF THIS VITAL INFORMATION IS STRONGLY ENCOURAGED!!!11!

I agree with Larry Taylor that JSC-1 is a crappy simulant. Without the iron, derived from both local and extra-selene (meteoric) sources, embedded in the simulant, there is little chance that the lunar oxygen prize will be won.

Dennis

Not to worry, I get high grade alumina of resistivity 10^13 ohm.cm (http://www.omega.com/pptst/ORX_INSULATORS.html) to melt in the lab using microwave resonant cav1ties.

You can melt practically anything rapidly if you choose the right sample geometry, frequency and field distribution.