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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

#101

Post by [deleted] »

OneDonOne wrote: post #95
rayiner wrote: post #83

Earlier quoted context omitted.

> Is my borderline childish understanding of basic physics THAT off because I cannot see the value or utility (beyond a small smear of niche edge cases) of space-based compute? In the real world, "physics" is not necessarily the gating factor. There is a major concern about the environmental footprint of terrestrial data centers, to the point where major U.S. states are enacting moratoriums: https://www.governor.ny.g…

If the "physics" tells you that your satellite cannot radiate heat away from your nVidia GPU cluster because each H100 needs 1.1 meter square of radiator, then opinions do not matter. The same applies to power supply and bandwidth.

[deleted]

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

#102

Post by alex_duf »

darth_avocado wrote: post #49
rrr_oh_man wrote: post #41

Earlier quoted context omitted.

> Only the third country to achieve this. What do you mean by this ?

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

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

#103

Post by pfdietz »

alephnerd wrote: post #100
pfdietz wrote: post #99

Earlier quoted context omitted.

What are the assumptions behind that 1.1 m^2 figure?

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 would have to radiate this energy too) but the radiator could become much smaller.

The other problem is assuming the radiator is intercepting sunlight. But it can be shaded by reflective films or kept edge-on to the Sun.

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

#104

Post by rayiner »

OneDonOne wrote: post #95
rayiner wrote: post #83

Earlier quoted context omitted.

> Is my borderline childish understanding of basic physics THAT off because I cannot see the value or utility (beyond a small smear of niche edge cases) of space-based compute? In the real world, "physics" is not necessarily the gating factor. There is a major concern about the environmental footprint of terrestrial data centers, to the point where major U.S. states are enacting moratoriums: https://www.governor.ny.g…

If the "physics" tells you that your satellite cannot radiate heat away from your nVidia GPU cluster because each H100 needs 1.1 meter square of radiator, then opinions do not matter. The same applies to power supply and bandwidth.

The radiator is much more efficient than the solar panels (for obvious reasons), so that’s not the limiting factor.

As to power, Caltech is already at 2-3 pounds per square meter: https://magazine.caltech.edu/post/sspp-space-solar-power-pro...

> Another way to think about it: An SSPP spacecraft with a 60-meter-by-60-meter surface area made using today’s space PV-cell technology would cost $36 million and weigh nearly 9,000 pounds, or almost as much as a Ford F-450 truck. With the ultra-lightweight PV-cell technology Atwater envisions, it would cost just $450,000 and weigh about 300 pounds, or about as much as an IKEA three-seat sofa

That’s megawatt-level solar power under 5 tons using today’s leading edge technology. Starship super heavy can launch 100 tons into LEO.

As to bandwidth, Starlink V3 backhaul capacity is 1 terabit. Microwave radio frequencies have an insane amount of bandwidth.

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

#105

Post by throwaway7783 »

shevy-java wrote: post #78

It's so sad that the Modi clique controls India. If India could become a real democracy, it could be competitive in the long run against China, because assuming similar quality and costs, people in democracies would much rather support a democracy than sinomarxist China or crazy-oligarch orange king country. But with Modi in charge, none of that is possible. Old men really need to leave politics, they just cause too…

I haven't followed Indian politics in a while, but I don't understand the "real democracy" comment. Can you elaborate on this? Or is it because Modi won three elections in a row?

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

#106

Post by numpad0 »

MobiusHorizons wrote: post #92
numpad0 wrote: post #55

Earlier quoted context omitted.

Rockets are usually two-staged + satellites. The booster take it to outside of the atmosphere, then the upper stage puts it into a ballistic trajectory, and the payload does the circularization burn 45 minutes or so after the liftoff at the peak of the parabola. Above is the basic semantics, and it can be further optimized, such as by extending battery power for the second stage to use it for circularization, inserti…

> Rockets are usually two-staged + satellites. I think that only applies to liquid fueled rockets. At a minimum the Scout family of rockets (USA) and the Lambda 4s (Japan) both use 4 stages. That is what I was trying to say above. The sibling comment also points out that you at least need a third stage to circularize the orbit, since you can't re-light solid rocket motors. I'm not exactly clear on why its 4 and not 3…

I think it's for maneuvering. At least L-4S seemed to have had 3rd for the pitchover and 4th for the apogee kick. The first two were spin stabilized and unguided for political reasons. "Payload" stages built more like satellites are better suited for precise guidance.

(ISAS side of Japanese space programs is chock full of political BS, everything from the pencil rocket that continued on from IJN rocket researches to the "unguided" L-4S to the LUNAR-A probe with diameter of approximately 152-155mm to one-man laptop launchable Epsilon LV concept focusing on "civilian low-cost rapid launch demands")

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

#108

Post by OneDonOne »

alephnerd wrote: post #97
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…

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 or…

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.

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

#109

Post by dyauspitr »

ghm2199 wrote: post #16

A small but bright light in an economy where manufacturing jobs are hard to come by ( https://archive.ph/Haj8n ).

It’s a strange place. They’re building out expressways and railways at a breathtaking pace (something like an entire Switzerland’s worth of new track every year), are simultaneously building out multiple nuclear reactors, exports and manufacturing are shooting up, but the cities still look like shit.

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

#110

Post by alephnerd »

OneDonOne wrote: post #108
alephnerd wrote: post #97

Earlier quoted context omitted.

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 or…

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…

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

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

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