I find HN and the tech circles to be one of the main community pillars holding up X. None of my social friends use it anymore, but links absolutely abound here, and it seems like the standard line is to pretend Elon, Grok, all the one button revenge and child porn etc don’t exist. I truly can’t fathom the amount of not thinking about it it would take to keep using the platform.

I am with you 100%.

It was easy to support SpaceX, despite the racist/sexist/authoritarian views of its owner, because he kept that nonsense out of the conversation.

X is not the same. Elon is actively spewing his ultraconservative views on that site.

Now that these are the same company, there's no separation. SpaceX is part of Musk's political mission now. No matter how cool the tech, I cannot morally support this company, and I hope, for the sake of society, it fails.

This announcement, right after the reveal that Elon Musk reached out to Jeffrey Epstein and tried to book a trip to Little St. James so that he could party with "girls", really doesn't bode well.

It's a shame you can't vote these people out, because I loved places like Twitter, and businesses like SpaceX and Tesla, but Elon Musk is a fascist who uses his power and influence to attack some of the most important pillars of our society.

The point of the Starship program is to drop the cost of a kg going to space significantly - this isn't meant to be launched with rockets that aren't fully reusable.

Wouldn't they?

Yes but if the solar panel area scales linearly with radiator area, the problem doesn't get worse?

I'm not the best person to make that case as I can only speculate (land cost, permitting, latency, etc). /Shrug

In all the conversations I've seen play out on hacker news about compute in space, what comes up every time is "it's unviable because cooling is so inefficient".

Which got me thinking, what if cooling needs dropped by orders of magnitude? Then I learned about photonic chips and spintronics.

> space is called “space” for a reason.

That equation have surface area ? What if new material found to be extremely large surface area to weight ratio to dissipate lots of heat ?

you put the radiators and the rest of the satellite within the shade of the solar panels, you can still make the area arbitrarily large

EDIT: people continue downvoting and replying with irrelevant retorts, so I'll add in some calculations

Let's assume

1. cheap 18% efficient solar panels (though much better can be achieved with multijunction and quantum-cutting phosphors)

2. simplistic 1360 W/m^2 sunlight orthogonal to the sun

3. an abstract input Area Ain of solar panels (pretend its a square area: Ain = L ^ 2)

4. The amount of heat generated on the solar panels (100%-18%) * Ain * 1360 W / m ^ 2, the electrical energy being 18% * Ain * 1360 W / m ^ 2. The electrical energy will ultimately be converted to computational results and heat by the satellite compute. So the radiative cooling (only option in space) must dissipate 100% of the incoming solar energy: the 1360 W / m^2 * Ain.

5. Lets make a pyramid with the square solar panel as a base, with the apex pointing away from the sun, we make sure the surface has high emissivity (roughly 1) in thermal infrared. Observe that such a pyramid has all sides in the shade of the sun. But it is low earth orbit so lets assume warm earth is occupying one hemisphere and we have to put thermal IR reflectors on the 2 pyramid sides facing earth, so the other 2 pyramid sides face actual cold space.

6. The area for a square based symmetric pyramid: we have

6.a. The area of the base Ain = L * L.

6.b. The area of the 4 sides 2 * L * sqrt( L ^ 2 / 4 + h ^ 2 )

6.c. The area of just 2 sides having output Area Aout = L * sqrt( L ^ 2 / 4 + h ^ 2 )

7. The 2 radiative sides not seeing the sun and not seeing the earth together have the area in 6.c and must dissipate L ^ 2 * 1360 W / m ^ 2 .

8. Hello Stefan-Boltzmann Law: for emissivity 1 we have the radiant exitance M = sigma * T ^ 4 (units W / m ^ 2 )

9. The total power exited through the 2 thermal radiating sides of the pyramid is then Aout * M

10. Select a desired temperature and solve for h / L (to stay dimensionless and get the ratio of the pyramid height to its base side length), lets run the satellite at 300 K = ~26 deg C just as an example.

11. If you solve this for h / L we get: h / L = sqrt( ( 1360 W / m ^ 2 / (sigma * T ^ 4 ) ) ^ 2 - 1/4 )

12. Numerically for 300K target temperature we get: h/L = sqrt((1360 / (5.67 * 10^-8 * 300 ^ 4)) ^ 2 - 1/4) = 2.91870351609271066729

13. So the pyramid height of "horribly poor cooling capability in space" would be a shocking 3 times the side length of the square solar panel array.

As a child I was obsessed with computer technology, and this will resonate with many of you: computer science is the poor man's science, as soon as a computer becomes available in the household, some children autodidactically educate themselves in programming etc. This is HN, a lot of programmers who followed the poor man's science path out of necessity. I had the opportunity to choose something else, I chose physics. No amount of programming and acquiring titles of software "engineer" will be a good substitute for physicists and engineers that actually had courses on the physical sciences, and the mathematics to follow the important historical deductions... It's very hard to explain this to the people who followed the path I had almost taken. And they downvote me because they didn't have the opportunity, courage or stamina to take the path I took, and so they blindly copy paste each others doomscrolled arguments.

Look I'm not an elon fanboy... but when I read people arguing that cooling considerations excludes this future, while I know you can set the temperature arbitrarily low but not below background temperature of the universe 4 K, then I simply explain that obviously the area can be made arbitrarily large, so the temperature can be chosen by the system designer. But hey the HN crowd prefers the layers of libraries and abstractions and made themselves an emulation of an emulation of an emulation of a pre-agreed reality as documented in datasheets and manuals, and is ultimately so removed from reality based communities like physics and physics engineering, that the "democracy" programmers opinions dominate...

So go ahead and give me some more downvotes ;)

If you like mnemonics for important constants: here's one for the Stefan Boltzman constant: 5.67 * 10^-8 W / m^2 / K ^ 4

thats 4 consecutive digits 5,6,7,8 ; comma or point after the first significant digit and the exponent 8 has a minus sign.

the radiators would be lighter compared to the solar panels, and slightly smaller surface area so you can line them back to back

Water is not needed to move heat. Heat pipes do it just fine. There's one in your laptop and one in your phone too. It does scale up.

please check my didactic example here: https://news.ycombinator.com/item?id=46862869

"Radiators can shadow each other," this is precisely why I chose a convex shape, that was not an accident, I chose a pyramid just because its obvious that the 4 triangular sides can be kept in the shade with respect to the sun, and their area can be made arbitrarily large by increasing the height of the pyramid for a constant base. A convex shape guarantees that no part of the surface can appear in the hemispherical view of any other part of the surface.

The only size limit is technological / economical.

In practice h = 3xL where L was the square base side length, suffices to keep the temperature below 300K.

If heat conduction can't be managed with thermosiphons / heat pipes / cooling loops on the satellite, why would it be possible on earth? Think of a small scale satellite with pyramidal sats roughly h = 3L, but L could be much smaller, do you actually see any issue with heat conduction? scaling up just means placing more of the small pyramidal sats.

attitude control doesn't need to consume propellant, there's reaction wheels.

but you'd rarely ever need it though: it just needs to rotate at a low angular velocity of 1 rotation per year to keep facing the sun.

https://en.wikipedia.org/wiki/Spacecraft_attitude_determinat...

Fluid in heat pipes moves through capillary action.

No, we just "assume" (i.e. know) that radiation in a vacuum is a really bad way of dissipating heat, to the point that we use vacuum as a very effective insulator on earth.

Yes, you can overcome this with enough radiator area. Which costs money, and adds weight and space, which costs more money.

Nobody is saying the idea of data centers in space is impossible. It's obviously very possible. But it doesn't make even the slightest bit of economic sense. Everything gets way, way harder and there's no upside.

which house?