Chemistry

Mining with minibots and mirrors needs a plan.

Recyclers do a lot of automated sorting. What are the ways?

On Earth there are storage tanks, processing tanks, gas storage tanks. They buffer production of materials before consumption. Can we go direct and have no stores at the site? Or are the raw materials scattered and need different handling at different places. Water is local, for example.

(BBC) with any mine it can take up to 50 years before you have a decent production describes mining in Greenland in the cold. Our process has to be automated and exponential and rapid. Conventional mining is not going to get that.

Why we can't refine chemically

A swarm mirror mass is around 5g/m², we have an assumed 1km² mirror which has the additional function of a sail when needed, 3x payload, roughly 20 tonnes per mirror. So the swarm has a mass 4E18kg which is 0.1% of the mined ore. That is a hint of the extraction efficiency required at the refinery. Given the geology of the host with a lack of water transport we are not going to find the concentration of ores normally searched for on Earth.

It is unlikely that unmanned conventional commercial-style refining of undifferentiated (or at least unexplored and unspecified) ore will produce clean products useful for manufacture. We need to create an all-purpose one-stage process which fills reserves with pure elements. Given an adequate energy source, we can do that.

• transform raw material to charged plasma
• pass through mass spectrometer
• catch elements in traps

If the traps can produce quantized shaped weights then we have the basis of an engineering feedstock.

I would hope that atomic construction of minibots from very similar directed charged atom streams solves the manufacturing process. This is standard 3D printing, but with atoms rather than inkjet heads. The same mass spectroscope manipulation is being repurposed. If we can scale the concept to get 1% of the host fed atom by atom beween charged plates, we have gone a long way toward a successful prototype. Having a vacuum at the surface could be a major advantage.

The unsolved issue of unused gas

The atmosphere column is under 4E15 atoms/cm² (1E8 atoms/cm³ at the surface) of (H₂, O₂, Ar, H₂O). The surface is 7.48E7km². Increasing the surface pressure would eventually mess up the refiner and builder processes. The atmosphere currently contains 3E33 atoms. We're launching 1.8E41 atoms, at 1E-3 efficiency that's refining 1.8E44 atoms processed. If even 10% of those are gas into the atmosphere we're increasing the pressure by a factor of 6E10 to 0.06 bar which is not a pressure the refinery or builder can operate at. While we can commence without containment, keeping the waste gas contained will become a problem from a fairly early stage and at the moment we have no suggested solution. We cannot maintain a vacuum in each minibot, we have the natural resource of the surface vacuum, we must preserve that resource. The solar radiation will presumably not clean that much extra pressure quickly enough to keep the vacuum self-stabilized.

Without remedial trapping of gases, the planet will lose its ultra-high vacuum after just 2E4 launches which is plainly unacceptable. Wrecking the host environment for a prototype swarm so small, with so little practical benefit, would not be justified. Whether reprogramming after, say, 2E3 launches, having gained practical experience of the environment and challenges, would allow a solution to be implemented, I'm not sure. I would much rather know how to solve the problem at an early stage, on paper, before signing off on a build.

1. While not a solution, we can mitigate by a factor of perhaps a hundred if we direct all gases onto group I or II isotope heaps. Those would need pre-setting on the empty clip before attachment. All H, O and halogens would be mopped up. I don't think we have a mechanism to mop up hydrogen, nitrogen or noble gases. Hg and S would also be a gas during daylight and not trapped but they might be lower proportions of the raw material than the main gas contaminants.
2. The extent of mitigation is how the plasma is contained prior to beam discrimination, and what proportion of plasma atoms will not be one-plus charged and hence miss the traps. Whatever we do in the beam cannot be as effective as capture and disposal away from the surface vacuum but we have no pump and we cannot freeze or contain. Selective chemical capture, with a different trap for each heap, is the best I can come up with so far.

Observations

1. A minor note, but I've always thought of charged particles as arriving hot and fast as in particle accelerators. They need not. They can be very slow streams of chilly atoms which will do no harm to the substrate as it builds up. They just need directing. And not to bounce.
2. If my assumption that shade and line-of-sight walls will keep the factory bots at a controlled temperature throughout the day is faulty, we have a second unsolved problem.