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India's first privately-developed rocket reaches orbit on debut launch

arstechnica.com

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Re: India's first privately-developed rocket reaches orbit on debut launch

#201

Post by foobarian »

pfdietz wrote: post #103
alephnerd wrote: post #100

Earlier quoted context omitted.

OP is quoting Mikhail Klassen at Planet Labs [0]. The cost of replacement is exorbitant for commercial usecases, but is acceptable for defense usecases. The issue is too many people are looking at the commercial usecase while ignoring the defense usecase that is what is actually driving the conversation and dealflow in this segment. [0] - https://www.mikhailklassen.com/posts/orbital-data-centers/or...

Ok, there are at least two bad assumptions there. First, it assumes the radiator is at the same temperature as the GPU. But radiators become dramatically more effective as temperature increases, with radiated power increasing as the fourth power of absolute temperature. So a heat pump that drives the radiator at higher temperature could make the radiator far smaller. More power would be required (and the radiator wou…

The other neat thing is that in space, the background temperatures are a lot lower than Earth due to lack of atmosphere, and available potentially more often than 1/2 the day cycle depending how high you're prepared to orbit.

Re: India's first privately-developed rocket reaches orbit on debut launch

#202

Post by notahacker »

pantalaimon wrote: post #198
notahacker wrote: post #128

Earlier quoted context omitted.

The unit economic tradeoffs aren't quite that straightforward (beamed power is lossy enough to require more panels[1], but solar cells and satellite structures have longer useful lives than inference chips so over longer time periods you likely end up launching more stuff into space with disposable datacentres anyway[2], particularly given the datacentres also need bigger radiators. Other issues which favour power be…

> but solar cells and satellite structures have longer useful lives than inference chips The limiting factor on the lifetime of any satellite is fuel. Especially for large structures that are influenced a lot by atmospheric drag and solar wind.

Sure, but periodically refilling a propellant tank for a few large SBSP structure on-orbit involves less complexity than replacing racks of inference chips distributed across constellations of satellites as proposed by current filings. Which is why the latter structures are designed to be disposable and the former not.

SPSP proposals tend to operate in higher orbits than ODC proposals too, as they're less affected by latency and radiation, so their station-keeping requirements are less propellant-intensive.

Re: India's first privately-developed rocket reaches orbit on debut launch

#203

Post by amluto »

holoduke wrote: post #186
OneDonOne wrote: post #91

Earlier quoted context omitted.

This borders on science fiction. 88,000-and 1-million satellite clusters (as claimed in your link) are hard to take seriously, especially with the possibility of Kessler Syndrome. Also: 1. How do you cool your chips? Vacuum is a thermal insulator, so radiators are required to remove heat. nVidia (or even ASICs) require much and specialised cooling. 2. How does one radiation harden a H100? 3. I'm also seeing where TCO…

Why do you need radiation hardening? We don't need hyper deterministic systems in those setups.

You need your chip to not completely fail. Latch-up can destroy things. A complete failure of a SERDES may dramatically reduce the utility of the whole system.

Re: India's first privately-developed rocket reaches orbit on debut launch

#204

Post by lanstin »

cyberax wrote: post #174
mayama wrote: post #162

Earlier quoted context omitted.

In case of collision in LEO, wouldn't the debris have chance to go high altitude and cause further collisions?

No. It'll stay in essentially the same orbit. During collision, some of the energy will be lost, so the fragments will necessarily have a lower orbit. The only thing that can accelerate fragments into a substantially higher orbit is the energy of elastic deformation of material during the explosion.

Can’t two solid object with equal kinetic energy collide in such a way that most of the energy goes into one of them, giving it a velocity that boosts its orbit while the other one has lower velocity and de-orbits?

Or one object explode into two fragments, equal and opposite relative velocity, again pushing the one half into a higher orbit and de-orbiting the other half?

(Honest question, math major, never took orbital mechanics or played KSP much).

Re: India's first privately-developed rocket reaches orbit on debut launch

#205

Post by pfdietz »

foobarian wrote: post #201
pfdietz wrote: post #103

Earlier quoted context omitted.

Ok, there are at least two bad assumptions there. First, it assumes the radiator is at the same temperature as the GPU. But radiators become dramatically more effective as temperature increases, with radiated power increasing as the fourth power of absolute temperature. So a heat pump that drives the radiator at higher temperature could make the radiator far smaller. More power would be required (and the radiator wou…

The other neat thing is that in space, the background temperatures are a lot lower than Earth due to lack of atmosphere, and available potentially more often than 1/2 the day cycle depending how high you're prepared to orbit.

A reflector could let the radiator see dark sky all around, even in low orbit. There are drag concerns.

Re: India's first privately-developed rocket reaches orbit on debut launch

#206

Post by amluto »

pfdietz wrote: post #134
OneDonOne wrote: post #132

Earlier quoted context omitted.

Again, Smaller radiator = bigger heat pump + more batteries and solar panels Satellites have a mass and power budgets. Your scheme only looks at temperature. If you want to build infinitely large AI Data satellites, go ahead.

[flagged]

The numbers are easy to run, and the added power consumption is no joke. It’s even worse if your heat pump fails to achieve Carnot efficiency. Never mind that heat pumps can be heavy and may be completely destroyed by even a tiny micrometeoroid strike.

Re: India's first privately-developed rocket reaches orbit on debut launch

#207

Post by pfdietz »

pantalaimon wrote: post #194
OneDonOne wrote: post #116

Earlier quoted context omitted.

> Ok, there are at least two bad assumptions there. > First, it assumes the radiator is at the same temperature as the GPU. But radiators become dramatically more effective as temperature increases, with radiated power increasing as the fourth power of absolute temperature. So a heat pump that drives the radiator at higher temperature could make the radiator far smaller. Carnot's theorem and refridgeration cycles rea…

Why do you need batteries? Why do you think the solar panels to run the heat pump require as much space as you save on the radiator? And GPUs operate just fine at 90°C

It's not just space, it's mass. A solar panel can be made very low in mass. The physical limit comes from the absorption of light in a thin layer of semiconductor. For CdTe, this would be about 1 micron. PV in space could be gossamer thin sheets of thin film semiconductors, with tremendous power/mass.

Re: India's first privately-developed rocket reaches orbit on debut launch

#208

Post by LargoLasskhyfv »

OneDonOne wrote: post #91
alephnerd wrote: post #48

Earlier quoted context omitted.

Also, Pixxel, Skyroot, and Agnikul are targeting orbital data center launches this year for defense applications (which is what the entire ODC story is about). The US NRO already uses India's Pixxel [0] along with Finland's ICEYE (which is now co-manufacturing synthetic aperture sats in India with Agnikul [1]) for hyperspectral scanning. Edit: can't reply > But.. why? Missile Defense and C4ISR [2]. Seconds matter, so…

This borders on science fiction. 88,000-and 1-million satellite clusters (as claimed in your link) are hard to take seriously, especially with the possibility of Kessler Syndrome. Also: 1. How do you cool your chips? Vacuum is a thermal insulator, so radiators are required to remove heat. nVidia (or even ASICs) require much and specialised cooling. 2. How does one radiation harden a H100? 3. I'm also seeing where TCO…

1. By using some form of liquid droplet radiator, as described in these:

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

https://ntrs.nasa.gov/citations/19850005591

https://ntrs.nasa.gov/citations/19810062992

https://spectrum.ieee.org/orbital-data-centers-heat

2. By producing them on intel 18A, like Starfire:

https://duckduckgo.com/?q=intel+foundry+18A+starfire

( Or going for different substrates, like Gallium-arsenides, Gallium-nitrides, Silicon on Sapphire, by using https://en.wikipedia.org/wiki/Heterojunction_bipolar_transis... on https://en.wikipedia.org/wiki/Indium_phosphide 's , enabling insane speeds & photonics.

To be fabbed here, possibly:

https://www.nist.gov/news-events/news/2026/06/department-com...

Or whichever other new metamaterial may come along. )

Now imagine the medium of these liquid droplets to directly flow through micro-capillaries in on-die cooling channels.

Good Morning! Ring, Ding, Ding, Rrrrriiiinnnnng!

Re: India's first privately-developed rocket reaches orbit on debut launch

#209

Post by kilroy123 »

alex_duf wrote: post #102
darth_avocado wrote: post #49

Earlier quoted context omitted.

Probably meant the third country with a private sector capability to launch rockets, US and China being the other two.

There's New Zealand as well with RocketLab

They're still a US company that just launches from there. Headquartered in California.

Re: India's first privately-developed rocket reaches orbit on debut launch

#210

Post by avmich »

Alive-in-2025 wrote: post #176
OneDonOne wrote: post #91

Earlier quoted context omitted.

This borders on science fiction. 88,000-and 1-million satellite clusters (as claimed in your link) are hard to take seriously, especially with the possibility of Kessler Syndrome. Also: 1. How do you cool your chips? Vacuum is a thermal insulator, so radiators are required to remove heat. nVidia (or even ASICs) require much and specialised cooling. 2. How does one radiation harden a H100? 3. I'm also seeing where TCO…

Yeah, there's no solution for heat dissolution at this time. You can run a few cpus in space, you are a few seconds closer to the data to figure out something basic, but you cant do that much calculation. If you do much cpu intensive stuff, you just get hot quickly and you can't dissipate the heat. I'm sure new ways to cool down will be developed, but there's not even any experimental techniques, right?

ISS collects ~250 kW solar power. All of that needs eventually to be dissipated - the energy removed by communication radiowaves is small. ISS routinely handles this thermal question for decades.

There is nothing magical with cooling in space. Just a different environment - a rather well studied already, we send satellites to space for some 70 years almost. Saying there is no solution is incorrect - we have options, we have numbers, we can point to concrete questions and answers.

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