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How hot do you think black objects in space get? Something like 10°C. Look up thermal equilibrium of an ideal black body.
by svantana 5mo ago
How hot do you think black objects in space get? Something like 10°C. Look up thermal equilibrium of an ideal black body.
- philipallstar 5mo agoBut are they doing work internally that generates heat? Genuine question.
- Schiendelman 5mo agoThey are. But only as much heat as they get from the solar radiation that's hitting them anyway. Exactly that amount.
- saalweachter 5mo agoExcept you aren't leaving that heat in place. You're concentrating it into a very small area of compute. If you don't spread that heat back out, it's going to find a much higher thermal equilibrium than the solar panels themselves would find just absorbing the sunlight and radiating the energy back into space. It's like you've pointed a magnifying glass at your compute, except with electricity, which means you can reach temperatures higher than you can with a magnifying glass.
- Schiendelman 5mo agoI guess I'm curious: all the comments I see about this act as if the people proposing putting data centers in space are complete idiots. Do you believe they are complete idiots?
- saalweachter 5mo agoNo, I think they're charlatans.
- senordevnyc 5mo agoIf they’re actually serious about this, they could simply address the points about cooling that numerous experts have raised. But they haven’t done that, at least not that I’ve seen. I have no idea whether they’re complete idiots, and I don’t really care. Maybe it’s idiocy, maybe it’s hubris, maybe it’s a grift, I have no idea. But until I see a compelling solution to this known problem, or a compelling suggestion as to why they’re not sharing a solution, I’ll continue to think they aren’t particularly smart or serious about this.
- Schiendelman 5mo agoWhat if it's actually not that hard to cool something in space, and y'all just have these beliefs about the people talking about this that make you think there must be something obvious they aren't thinking about?
- senordevnyc 5mo agoIf it’s not that hard, then perhaps someone can just point to the simple math of how it would work. It’s not like only idiots who know nothing about space are pointing out the cooling issue: https://taranis.ie/datacenters-in-space-are-a-terrible-horrible-no-good-idea/ https://taranis.ie/datacenters-in-space-are-a-terrible-horri...
- Schiendelman 5mo agoThe problem is, that person is deeply underinformed. For instance: "you don't lose that much power through the atmosphere" Assuming you can point the orbiting panels at the sun and remain direct, you lose 80% of your power through the atmosphere (from angle and day/night). On the ground you lose 25% even if your panel is directly below the sun pointed exactly at it, which is never the case in many latitudes. And of course it's not trivial to radiate heat. But it's also a fairly simple mechanical problem. You pump the heat to spread it out, and radiate it. You've already got the surface area shaded by the panels (which is more than enough, because the panels don't absorb 100% of solar radiation). Sure, you need a lot of them. Starship V3 is probably about to get us past 100 tons of payload capacity - even if they blow up a few first. The key people miss is that you don't have to spend money on ongoing cooling once the thing is in space. This isn't going to save money now, but the cost lines are going to cross.
- fatbird 5mo agoThey're hucksters who know that adding "in space!" to a sales pitch is a free booster for tech enthusiasts. It's the same way that Sam Altman talks about the risks of AI deciding to kill humanity: because that's dramatic and attention grabbing, and also the most unlikely outcome. Talking about it keeps us from talking about the real, ground level problems like the massive, unplanned-for disruption in jobs and education. They just need to keep the money tap flowing, and tomorrow can worry about itself. Who's going to hold them accountable for data-centres-in-space five years from now, when they don't exist? Has Musk suffered any blowback from his hyping the Hyperloop that never materialized?
- Schiendelman 5mo agoSo you've only looked at the very loud people talking about this, and not the hundreds of quiet people working on this?
- saalweachter 5mo agoI mean, if someone wants to pay you to do a lot of very interesting R&D that will never result in an alternative to ground-based datacenters, more power to you? It might even be useful in other circumstances. Better radiative cooling systems, hardening commercial high-end compute for space, etc etc. R&D you can feel proud of, even if your bosses are only paying you to do it to fleece rubes who think it's the next trillion dollar industry.
- fatbird 5mo agoHow many smart people worked quietly on Zuck's metaverse for years? How many knew it was never going to work at some point on the line to $70 billion wasted, but thought "hey, maybe I'm wrong, and it's an interesting job that pays well"? How many smart people worked quietly at Theranos, knowing that a drop sample from a thumb was incapable of carrying sufficient blood volume for a legitimate sample, but thought "hey, maybe someone will figure something miraculous out that violates a basic tenet of my professional experience"?
- 5mo ago
- nomel 5mo agoThis is a mostly a software developer forum, not an engineering forum. Expect expertise and viewpoints to match that.
- philipallstar 4mo agoI didn't think of it like that. Does that mean all solar radiation is heat from when it hits a solar panel? I thought it would be something like solar -> chemical -> electrical -> heat.
- db48x 5mo agoIf you gather 1kW of power from the sun then you have to reject 1kW of heat once you are done with whatever computation you are doing. There’s a bit more heat absorbed from the environment since some sunlight strikes parts of your satellite that are not solar panels, but it’s not too bad. Starlink satellites, just to pick a relevant example, do not need a radiator at all because they stay mostly edge–on to the sun and they can radiate all the heat through their own surface area. The ISS needs big radiators because they want it to be comfortable for humans, but electronics can run significantly hotter than that.
- adastra22 5mo agoIn the vicinity of the Earth, they get to about the temperature of the Earth. That’s not a coincidence. Hotter if they are actively generating heat.
- Geof25 5mo agoSo you can have datacenters in space, you are just not allowed to use them
- jeltz 5mo agoNot using them would also solve all issues with cosmic radiation.
- Symmetry 5mo agoNobody (sane) is talking about putting nuclear reactors on Satellites in close Earth orbit so we don't have to worry about them generating heat. They've got solar panels that move some of the solar energy they absorb to a central location which presents problems in moving the waste heat back out so that spot doesn't get too hot. But that doesn't change the overall equilibrium temperature.
- adastra22 5mo agoRunning a data center generates heat.
- Symmetry 5mo agoNot if you first absorb heat with your solar panels. Conservation of energy and all that.
- adastra22 5mo agoI'm not sure if you're being serious or not? Any use of power turns useful work into heat (conservation of energy and all that), which raises the temperature of the satellite, until radiative cooling can equalize within incoming heat (solar irradiation).