The emissivity of all kinds of common materials are very close to 1. For example, typical glasses are about 0.95, and anodized aluminum is about 0.85 (not lousy at all, unlike your claim). As for heat spreaders, like I said in my article, they already exist. Heat pipes are remarkable tech. And as I pointed out, you don't necessarily need them at all if you derate your ASICS from current designs. Static electricity isn't a significant issue at all. Safelites have had to deal with it since forever, and we know how to mitigate it. Radiation isn't a significant issue either for an application like Bitcoin mining. If a particular ASIC has an error due to radiation, just power cycle it. Plenty of real world satellites use cheap commercial parts with this strategy. And obviously, if you're spending a few billion launching Bitcoin miners, you can put some R&D into making custom designs that are more resistant. You're going to be doing that anyway to actually make the economics work and take advantage of the space environment. Rejecting heat to rock is a really stupid idea. Rock is a thermal insulator. That's why the London underground – and lots of other underground infrastructure – has endless problems keeping things cool underground.

I don't know where you could have gotten 0.85 from, try this:

Aluminum - Radiation Heat Emissivity

Radiation heat emissivity of unoxidized, oxidized and polished aluminum.

Heat spreaders and heat pipes are not at all the same thing, and either will result in a delta-T completely missing from your calculations. And minimising that will blow your mass budget. Re static electricity - yes there are mitigations, such as the aforementioned aluminium enclosure, but that will result in yet another delta-T missing from your calculations. Radiation: yes, we can check for single event upsets in software and discard them. That's not the main problem with radiation, though. Here's a TL;DR: https://nepp.nasa.gov/DocUploads/392333B0-7A48-4A04-A3A72B0B1DD73343/Rad_Effects_101_WebEx.pdf