Item — HN Reader

The projections are questionable, but this is something the US and China are experimenting with as well.

1 and 2 are still open questions, but these are not aimed to be commercial grade DCs - this is basically edge compute (think a handful of racks). 3 is not a problem for defense usecases. (EDIT: Discussion here seems to point out that data OP is using might be flawed [1]).

Ignoring the fact that just about every orbital data center startup in the US is funded by IQT and China's CMF has been doing something similar is bad from a defense perspective.

Based on dealflow, these aren't being targeted for consumer usecases in the short-term and whoever has been saying that is misleading.

> especially with the possibility of Kessler Syndrome...

India, Russia, China, and the US don't care about Kessler Syndrome - they have already launched and deployed ASATs. This also comes after India and China had a near collision in 2024 that was treated as an offensive action [0].

[0] - https://www.bloomberg.com/news/articles/2025-09-22/india-pla...

[1] - https://news.ycombinator.com/item?id=49039873

2 comments

    3 is not a problem for defense usecases.

Cost is the critical constraint for defense programs. Yes, militaries spend a shit-ton of money, but that's usually in a penny wise and pound foolish way. A dollar spent on your project is a dollar that's not spent on the innumerable things generals think are critical to their future wars like boondoggles, missiles, planes, ships, missile defense systems, etc.

The exception is if you're one of those rare projects. A starlink type constellation or launch capabilities certainly could be, but it's hard to imagine generals getting excited about compute in space just for the sake of it.

It is critical to avoid a boondoggle gap.

This reminds me of the railgun. Basic math and physics tells us that not only would the (very expensive) barrels wear out very quickly, but that it would have had to be fitted on on a nuclear-powered pocket battlecruiser.

Worse, the technology for firing any meaningful payloads from an electric gun (8" Small Diameter Bomb equivalents, guided, airburst, incendiary) simply does not exist.

Same as with Musk's California Vacuum Tunnel (which diverted attention from passenger rail). And his Neuralink. In the 1980s, it was nuclear pumped space-based lasers and Soviet particle beam weapons.

All of the above can be debunked with 2 years undergrad physics and a Casio calculator. Yet they were still taken seriously by high-level politicians and business, some of whom were deeply connected with the military-industrial complex.

People have shrugging of questions like 1 and 2, only for 3 to hit them very hard. But we will see if they can launch 600 of these satellites as they claim.

As raynier and pfdietz pointed out [0], the assumptions you are using aren't necessarily correct.

[0] - https://news.ycombinator.com/item?id=49039873

Ah yes. The heat pump.

My response:

Carnot's theorem and refridgeration cycles rear their head. Your heat pump still needs power to pump heat uphill., negating any savings from a smaller radiator. And what happens when you shrink a radiator? It becomes a high temperature radiator, meaning the GPU must operate outside its operational tmperature of about 70 degrees C. So small radiator = big pump + extra solar panels and batteries + dead GPU

Also, how do you deal with the added cost and complexity for the solar tracking mechanisms for the "edge-on-to-the-Sun" radiator?

Yes, that was your response. It was a terrible and obviously invalid response, as I explained.

You never explained why the GPU temperature had to increase. Could you explain that now? The GPU would be on the cold side of the heat pump, not the hot side.

> Also, how do you deal with the added cost and complexity for the solar tracking mechanisms for the "edge-on-to-the-Sun" radiator?

We ignore that issue, because we were debunking a bad argument about "the laws of physics". The laws of physics say nothing about budgets or complexity.

Soviets definitely experimented with airborne CO2 lasers.

It just goes to show magical thinking isn't just an American thing.

I can’t imagine how inefficient a country would be if they tamped down all their magical thinking. FFCS, SMILE, and EUVL are all magical thinking if you ask me. Some of the craziest things humans have ever conceived of.

Full-flow staged combustion is a rather logical - and not even particularly useful, we're talking about small percentage points - extension of staged flow combustion, and staged combustion is a rather obvious change to open-cycle schema - and I'm hyperbolizing just a little bit here.

Yes, it brings effects, and it's a cool technology. But saying that at least idea - or results - are fundamentally changing rocket engines... I think that's a stretch.

There’s nothing logical about trying to make non-oxidizing metal that can handle thousands of degrees of temperature, hundreds of bars of pressure, and a nearly pure-oxygen environment? The US essentially made fun of the Soviets for even trying. If you think it’s logical, you don’t understand the tech at all. It’s a borderline miracle, let alone simply “logical”.

Literal rocket scientists spent decades and careers saying it was a waste of time, and random people with zero expertise try to downplay it. I’ll never understand being THIS cocky is a subject one has clearly never touched.

Soviets were world leaders in liquid fuel rocket engines. They used oxygen-rich preburners in e.g very successful line of engines starting with RD-170. It was possible decades ago. And no downplaying.

laser enrichment of uranium