This article assumes that no extra mass is needed for cooling, i.e. that cooling is free. The list of model assumptions includes:

• No additional mass for liquid cooling loop infrastructure; likely needed but not included

• Thermal: only solar array area used as radiator; no dedicated radiator mass assumed

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Yizahi 15 hours ago | parent | next [-]

Author also forgot batteries for the solar shade transition period and then additional solar panels to charge these batteries during the solar "day" period. then insulation for batteries. Then power converters and pumps for radiators and additional radiators to cool the cooling infrastructure.

Overall not a great model. But on the other hand, even an amateur can use this model and imagine that additional parts and costs are missing, so if it's showing a bad outlook even in the favorable/cheating conditions for space DCs, then they are even dumber idea if all costs would be factored in fully. Unfortunately many serious journalists can't even do that mental assumption. :(

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torginus 10 hours ago | parent [-]

I'd say int makes much more sense to just shut off in the sunshade. The advantage of orbital solar, comes not so much from the lack of atmosphere, but the fact that depending on your orbit, you can be in sunlight for 60-100% of the time.

	▲	Yizahi 9 hours ago \| parent [-]
		That proposal I've seen a few times too, basically put up a constellation up there, linked with laser comms and then transfer data to the illuminated sats in a loop. That sounds possible, but I have doubts. First of all if we take 400 km orbit, the "online" time would be something like 50 minutes. We need to boot up the system fully, run comm apps, locate a peer satellite and download data from it (which needs to be prepared in a portable form), write it locally and start calculations, then by the end of the 50 min repeat. All these operations are slow, especially boot time of the servers (which could be optimized of course). It would be great if some expert could tell us if it is feasible or not.

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davedx 17 hours ago | parent | prev [-]

Yeah that's just flat out wrong then: you can't use the solar array as a radiator.

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jcattle 17 hours ago | parent [-]

Of course you can. You can use everything as a radiator. Unless you have something which is literally 0 Kelvin everything radiates.

See here for all the great ways of getting rid of thermal energy in space: https://www.nasa.gov/smallsat-institute/sst-soa/thermal-cont...

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notahacker 16 hours ago | parent | next [-]

You can use everything as a radiator, but you can't use everything as a radiator sufficiently efficient to cool hot chips to safe operating temperature, particularly not if that thing is a thin panel intentionally oriented to capture the sun's rays to convert them to energy. Sure, you can absolutely build a radiator in the shade of the panels (it's the most logical place), but it's going to involve extra mass.

	▲	dsr_ 10 hours ago \| parent [-]
		You also want to orient those radiators at 90 degrees to the power panels, so that they don't send 50% of their radiation right back to the power panels.

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oivey 11 hours ago | parent | prev [-]

You can rivet people onto the outside of the ISS to radiate heat, too, but it may be detrimental to the overall system.