This is an idea I had recently. For quick ROI, especially on early "prototype" sats that nobody trusts with their valuable data, one could start by mining bitcoin.<br><br>Bitcoin is a digital commodity that behaves like a currency. There are entire startups based around it. If you have bitcoins in your account, you can transfer to someone else's by publishing a transaction that only you can create. To make sure transactions are valid, instead of having a single third party verify them, a peer to peer system is used to allow everyone with a processor to check the transactions, over and over.<br>
<br>The creator's original goal was for it to employ CPU power so there would be easy entry and everyone could just check a box on their PC for a few starter bitcoins. However since the SHA256 hash was chosen, which is highly parallelizable, use of GPU (graphical processing unit) cards turned out to be massively more cost-effective. Currently the only energy-efficient ways are high end GPU cards and FPGAs, and these are employed by people ranging from hardware hobbyists to sophisticated server farms. Verification is known as "mining" because it rewards verifiers with bitcoins.<br>
<br>Bitcoins are distributed (at a rate of one block of 50 per 10 minutes, with difficulty automatically adjusted to keep the rate constant), to whoever solves the block (finds a qualifying, i.e. low numbered hash) first. It's like a race. The more computing power the whole network has, the lower the probability of getting a block per unit hashing power -- which translates to joules of energy depending on the hardware. If you can beat everyone else by using a much more efficient system or a cheaper power source, they eventually have to stop because their hardware no longer able to pay for the electricity it uses.<br>
<br>So on to my speculation: As long as blackbody cooling and cheap solar are sufficient to overcome the disadvantages of launch costs and custom manufacturing, space-based thinsats optimized for bitcoin mining (computing SHA-256 hashes) should be able to outcompete ground-based server farms. Thus miners who want to stay in the mining business will be forced to sell some of their bitcoins for dollars (or borrow against them) and purchase their own space-based thinsat rigs. Eventually, the profits and empirical results obtained from doing this should be useful enough to create more general-purpose thinsats and branch into robust data storage and general computation.<br>