Preparing the moon

[rogers_buck]

Given the rather unfriendly nature of the sharp little glass shards known as moon dust, wouldn't it be a good idea to "prepare" a landing site from LEO. What I had in mind was a laser or microwave transmitter in earth orbit that would "soften" a future landing site by melting it. Outside the atmosphere their is little in the way of disspersion effects to degrade a laser. <br /><br />I saw or read somewhere that lunar soil microwaves real nice melting easilly and forming a glassy substrate. At the least, the sharp edges could be softened and turned into micro spherrules.<br /><br />

 

[henryhallam]

I don't know much about masers but I think power source would be a problem so I'll talk about chemical lasers... (of course I don't know much about them either)<br /><br />Laser beams still spread over the very long distance. I think the beam used in the retroreflector ranging experiments, which they focus as tightly as they can, spreads to something like 5 miles diameter by the time it gets to the moon, with the intensity reducing proportional to 1/(beam diameter)^2<br /><br />Even if you could somehow solve the beam dispersion problem you'd still neat a honkin' big laser. The chemical laser used for ballistic missile defense tests is a one-shot device (without refueling) and takes up a whole 747 so I imagine it weighs something in the range of 50-200 tonnes. That only gets you one shot, and anyway I'm not sure it would be up to melting regolith even apart from the range issue. When used against ballistic missiles, it doesn't vapourise the missile, rather it just heats the surface of the missile booster's propellant tanks enough that they lose a little strength and fail from the internal pressure. I don't think moonrock is that fragile.<br /><br />Even if you could, why bother? Apollo managed to get down fine and the dust was a bit annoying, perhaps slightly hazardous during approach from a visibility point of view but precision guidance should fix that.

 

[johnsje]

Is this what you are looking for?<br /><br />http://www.space.com/adastra/adastra_moondust_060223.html

 

[crix]

At some point we're going to have to deal with the lunar and martian regolith in an untreated form. Our ultimate plans to populate the solar system are not very robust if they require turning a whole planet into glass. Even if it were just for a base area that area would be contaminated by anyone that ventured beyond the treated base-ground and returned. Concentrating on something like that would be diverting funds from research into next generation space suits, materials, hardware, and facilities that deal with learning how to live with the dust.

 

[rogers_buck]

I remember reading a post back in 1983 or so (usenet) from someone advocating a lunar atmosphere. They had run the numbers and came up with a sulfide gas (can recall which) that the moons gravity could maintain against photo-dissasociation and evaporation. The gas was a reasonable UV absorber and could support humidity. A designer atmosphere for our little moon. A few artificial storms would knock some of those sharp edges off those micro-grains.<br /><br />

 

[rogers_buck]

That's the article. Thanks.<br />

 

[crix]

Woah! That's an interesting idea, if only for the UV absorbtion. Thinking about artificial storms is probably a bit much though.<br /><br />

 

[rogers_buck]

Hard to get a handle on the required energy density at the target from that one artcle... <br /><br />Power is a problem but dispersion from the earths atmosphere is not. A laser fired at the moon should be withing the expected circle of confusion at the lunar distance. There are some techniques to actually improve upon the diffraction limits of spot size (circle of confusion) which use different wavelengths of light mixed together. The technique is used in IC laser lithography to get a smaller spot than is possible for a single laser but it may well not scale up to lunar distances...<br /><br />Chemical lasers such as HF produce lots of energy but at the expense of propellant mass. HF lasers are actually little different than rocket engines. Their single mode resonance cavities resemble rocket engines to me. I would guess a solid state laser and a stack of EDFA stages would be good but a bit of a power hog.<br /><br />A ground based laser might do the trick if there was some form fo dispersion compensation active optics employed. A remote sensor outside the atmosphere might close the loop back to the active optics. The earlier moon bounce lasers were either powerfull CW or Q-Switched/cavity dumped lasers with no active optics. Short soliton-like pulses might also help to avoid some degradations.<br /><br />The optics people are extrememly cleaver about hitting their targets, it seems it all depends on how much energy is required at the target. If the goal was to simply kick-off dangling molecules that add a chemical abrassiveness tot he moon dust that would take one different amount of energy than is required to remelt the tiny grains. The size of the particles are also a factor in selecting the kind of bombardment for best results.<br /><br />

 

[thinice]

I wonder how violent would be the atmosphere of a satellite of a close to the Sun planet.

 

[gsuschrist]

If one could vaporize a few hundred square feet...are we confident that the craft would land in that few hundred square feet? Seems the landing craft and everything else would have to be built with the precaution that we wouldn't.

 

[chriscdc]

Another advantage of using a intense pulsed system would allow you to melt the top few mm or so. A continous beam probably wouldn't be powerful enough to melt the material as the energy would be radiated away as heat.<br /><br />There are crowd control systems (grumble, civil liberties... etc) that plan to use microwave beams in order to vaporaise the top fraction of a mm of skin in order to cause pain. You could place a similar system on a lander which would melt the surrounding area after the lander has err landed. That way you can limit the dust that the crew would be exposed to in the immediate area. You could fit a similar system to a buggy.<br />Another advantage with this up close system is that you could use an image recognition sytem to avoid fryng local rocks. Thus you wouldn't have to worry about damaging the scientific value of the site.