India's first privately-developed rocket reaches orbit on debut launch
arstechnica.com
arstechnica.com
Agnikul is planning to launch semi-cryo kerosene rocket pretty soon. Their engine is 3d printed and use electric pump fed 25kN small engine. Planning to launch 4 clustered engines as first stage and already did suborbital test, with some parachute splash down reusability claims.
Astrobase is recent entrant. With decent funding and former ISRO scientists as core team, developing 800kN FFCS methalox engine. FFCS is called holy grail of liquid engines. They have acquired largest metal 3d engine and planning VTVL 1st stage reusability
Edit: can't reply
> But.. why?
Missile Defense and C4ISR [2]. Seconds matter, so most of the newer generation of missile defense systems are experimenting with how to offload compute at the edge to reduce C2 latency.
Most orbital sat startups in the US, China, and India are partially backed by military and intel oriented funds (eg. Starcloud and IQT/In-Q-Tel).
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[0] - https://www.nro.gov/news-media-featured-stories/news-media-p...
[1] - https://www.livemint.com/companies/news/agnikul-cosmos-iceye...
[2] - https://idsa.in/wp-content/uploads/2026/01/book-MISSION-SUDA...
But.. why?
Musk bandwagon-hopping? Investor bamboozlery? (Same diff?)
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?
- ed, disclosure: You seem to have edited your response whilst I was typing mine, adding in valuable links. Thanks!
Don't worry, most of the people online didn't get the memo on this.
One of the major selling points of orbital compute is power supply - more specifically, it turns out that, compared to beaming power from space, it's projected to be cheaper to move compute upwell instead - atmosphere losses for beamed power are just too big. Of course this doesn't matter if you can get cheap, clean power from elsewhere (e.g. nuclear).
This is in general data center case. Here, GP says the motivation is reducing C2 RTT, which makes sense for military applications.
We could. The usual stumbling block is how to ship fissile material upwell without the risk of a launch failure spreading highly radioactive material over several countries.
> What's the power loss from beaming down power?
I think it's about 10% from atmosphere alone, but you have to add losses from other components in the system, including light -> current -> RF and RF -> current legs, and I've seen estimates ranging from 15% to 40% efficiency end to end; this random article includes breakdown with estimates, that multiplies down to 37.5% efficiency end-to-end.
https://www.sciencedirect.com/topics/earth-and-planetary-sci...
EDIT:
This system design gives 7-14% end-to-end efficiency: https://arxiv.org/pdf/2206.08373
EDIT2:
Also to spell out another non-obvious aspect of beamed power, it turns out that it's not the efficiency that's the limiting factor per se, but land - you can improve efficiency by building larger rectennas, but it gets very expensive very quickly once you consider paying for land under them.
SNAP-10A
BES-5 (oops, sorry 'bout that Canada!)
TOPAZ-I
Kiwi, Phoebus, and NRX (Mars here we come!)
RD-0410 (Dossvidanya Solar System!)
SP-100
TOPAZ-II
Kilopower
The fact that the US, China, Russia, and India have already deployed ASATs means a Kessler effect if a question of when and not if.
It's a matter of time before Japan, SK, Iran, Israel, UAE, KSA, etc build similar capabilities.
[0] - https://www.bloomberg.com/news/articles/2025-09-22/india-pla...
The other comparison point is of course plain old terrestrial power sources, including energy storage in the mix if it relies heavily on solar power without a sufficiently global grid. Not having to launch into space buys a lot of power.
C2 RTT times and edge computation of large datasets collected in space make much more sense since unit economics aren't the driving factor, but are unlikely to need datacentres on the same scale as inference compute for the general population (another reason why this use case makes more sense)
[1]but I think the underrated problem with beamed power isn't just the low maturity of the technology, but that as soon as you start talking about sending power to earth via RF or laser you're going to encounter political opposition that makes objections to terrestrial datacentres seem tame.... [2]chips can in theory be replaced on orbit, but the "million satellite" filings are disposable. Replenishing propellant for a few large power stations, potentially on longer cycles, is a simpler task.
What kills that is simply costs of land. You have to put these larger rectennas somewhere, and land ain't getting cheaper.
Not now, but with solar power output doubling every few years how long before we run out of land?
Space based solar power has much bigger challenges in gaining acceptance, proving the physics works in real world conditions and delivering on its promises than the theoretical possibility that there is absolutely no unoccupied region of land or sea
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.
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.
This is damning with the faintest of praise. Beaming power from space is a terrible idea.
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.gov/news/first-statewide-moratorium-.... These legal and social roadblocks must be accounted for in analyzing the viability of orbital data centers.
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...
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.
> 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 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?
Sorry, that's all nonsense. Yes, the extra power needs to be radiated. But the advantage of operating at high temperature is so extreme that the more effective radiation will overwhelm that unless the heat pump is extraordinarily inefficient. If the heat pump would be perfect, operating at the Carnot limit, then if it doubled the absolute radiator temperature it would double the amount of energy to be radiated, but the area of the radiator would decrease by a factor of (2^4)/(2) = 8.
As for the second point, no, this does not require the GPU to operate at higher temperature. What made you conclude it would?
> Also, how do you deal with the added cost and complexity for the solar tracking mechanisms for the "edge-on-to-the-Sun" radiator?
I don't need to; I'm just debunking a bad argument. What you are doing there is called "moving the goalposts". But satellites normally have means of orienting PV toward the Sun. So, maybe have the radiator perpendicular to those? Those claiming the idea violates the laws of physics and using solar absoption on the radiator as part of the argument need to show no such scheme can work, even in principle.
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.
When someone else is wrong (or you feel they are), two options that work are to continue to respectfully provide correct information, or to stop replying. Getting into denunciation, spats, etc. is not a good option.
Almost every satellite needs attitude control, so this isn't something out of the ordinary. I'm not sure solar tracking mechanisms really fall into the "expensive" or "complex" categories in 2026.
And GPUs operate just fine at 90°C
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.
SSPP has already sent prototypes to space: https://www.caltech.edu/about/news/space-solar-power-project....
There's a ton of work being done on lightweight solar panels for space. E.g. https://ascentsolar.com/asti-technology-and-unique-advantage...
There may be an economic challenge - which seems to be the sort of problem mass manufacturing can solve very well.
There may be a compute model & latency problem, how do you organize model training when racks are much further apart than in traditional data centres (although speed of light is 50% faster in vacuum than glass fibre). But that's algorithms.
Relative to everything else in orbit, powering a rack of compute and some comms per satellite seems not really to be a physics problem.
"Much easier" overall is quite a claim.
I'll be shocked if it isn't.
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 for these are 78x their terrestrial equivalents [0]. Is that financial sustainable?
And there still remain issues with power supply, regulations, and bandwidth. This feels more like a thought experiment rather than an actual serious engineering or business case.
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...
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.
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?
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.
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.
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.
3 is not a problem for defense usecases.
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.
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.
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).
Sure, you can. Imagine shooting a bullet into a tungsten cube. The cube will go into a higher orbit, and the bullet will bounce back (and maybe de-orbit).
But the kicker here is that for this to work, the bullet has to be in a _higher_ orbit than the cube initially. So the end result is still fewer objects in higher orbits.
Another option is momentum transfer via elastic deformation - you shoot a bullet into a 45-degree facet of that tungsten cube, and the bullet then ricochets into a higher orbit. It ultimately works by momentarily storing the energy of the projectile as a plastic deformation of the facet. So it can't accelerate more than a few small fragments.
In actual reality it's estimated that several segments of LEO have already reached criticality, especially around 600 km: https://conference.sdo.esoc.esa.int/proceedings/sdc9/paper/3...
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?
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.
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!
This is space 101 and honestly, at this point, I consider bringing this up as disqualifying from giving criticism on the topic.
> nVidia (or even ASICs) require much and specialised cooling.
Whatever. They generate N kW of heat, you need to shed N kW of heat, and you need to fit that within your budget. End of worry.
Pro tip: if you can slice your problem so that individual satellite needs to shed less than M kW of heat, where M corresponds to how much heat some existing, deployed satellite platform handles, you can just do your initial design around that satellite platform, replacing the "business payload" with yours.
This is e.g. how the unfairly criticized recent "satellite swarm TPUs" paper from Google handled it. Everyone who brought up cooling revealed themselves as not having read the first page and not having thought about it seriously for more than 30 seconds.
> 2. How does one radiation harden a H100?
See that paper for some ideas and considerations, as this is part of what they focused on, after solving cooling by sizing the per-satellite payload power needs to Starlink.
I am regularly assured by HN denizens that orbiting data centers will never work.
For C4ISR usecases they solve the latency problem and are worth the spend needed.
Everyone on HN is talking about a commercial usecase that isn't under serious consideration.
The whole thesis around ODCs is to basically mass deploy a bunch of replaceable racks en masse and consistently, such that any geospatial intel can be processed at the edge.
Particularly for reusable liquid engines :)
Oh, and everyone gets a white herman miller chair (or a very good clone).
ISRO has a very good track record of launching rockets with solid state engines. I do wonder if almost all of their expertise was used for the first three stages(and they are not 3d printed)? And how much more difficult it is to make the last stage as compared to the first three, which as I understand, was the stage designed and tested by skyroot itself(manufactured by Wipro 3D).
- is there a place that you recommend where they teach you how rockets work, what is involved in building one, the math and physics behind it, materials required etc etc?
Maybe this helps: https://www.isro.gov.in/TechnologyTransfer.html
Consider how many rocket development efforts squandered 10X to 100X the money, and >8 years, without making it to orbit.
Using solid fuel for their first 3 stages also makes it far easier. I'd take that as evidence of their management wisely picking a good shape for the org's learning curve. Vs. chasing the long-odds bragging rights & likely heartbreaks of a liquid-fuels-only version 1.0.
I'm no expert, but I suspect that even if you apply a generous discount for being in India, Skyroot's economics are still quite impressive.
Edits: clarity
I wouldn't be too sure about the immigration part, when even a software engineer hire for a defence/defence adjacent job requires jumping through a number of bureaucratic hoops of security clearances. Even the companies with deep pockets don't always get the best people in the world -- they just get the best people that HR can actually hire.
Also, there are plenty of space companies that aren't in the US/UK/China who are hiring (and more willing to work with non-domestic employees since they're playing catch-up), and plenty of companies in US/UK/China who employ contractors that aren't subject to the same hiring restrictions as the first-party/defense-contracted company.
There are a lot more specialized/high-expertise roles here than the ones critical to a nation's space program (or fungible with making weapons). Random examples off the top of my head include crew/life support expertise, launch facility engineering, LEO consumer telecommunications, and more. Space hasn't been fully commodified/detached from government interests--not by a long suborbital burn--but it's moving that direction enough to thaw out the ability to immigrate for work a bit.
I am unsure about private salaries but in govt. jobs, because it follows a rigid structure, the salary is still lower than what you might expect and is around the mark of 20-25 thousand dollars per year. It's similar to administrative services or depending on the position, equal to teachers/professors .
I have heard my cousin say that its hard for people to move outside because for example SpaceX/NASA couldn't hire non-American person because of laws and regulations due to security purposes.
From what I know, my cousin actually got some job offers when he had gone to give a speech recently from Management companies
20-25k$ in India isn't bad but strictly speaking, Computer science earns comparable in India at the same level.
The value of the job is mostly in govt rather than private and the benefit of it is that the work is much less stressful rather than private companies stress and just like how NASA has some prestige attached to it in America, same way goes for ISRO in India.
I think so, but I can only say it about my cousin to whom this field of line was suggested by one of my uncles was that the most major prospect of a government job.
Within India, there is a very strong prestige surrounding govt. jobs, like a lot.
The cousin whom I am referring to actually even studied and gave some exams after becoming a rocket scientist to get into a sub part of civil services just on the side (to get even better salary), I am unsure if this is an Indian specific phenomenon or not, but the prospect of the govt job for most people is the combination of comfort,prestige etc.
The prestige of the govt job is so much to many people that another person I know has spent 7 years solely dedicated towards getting to a govt. job and they still sadly don't have it but they are close to getting it :-( and they denied one of the most prestigious private institutions just for the effort to study solely for govt. job (though they are from civil engineering background), they would've completed their degree by now and atleast gotten a package close to the cousin working in rocket science itself.
My cousin actually wanted to go into computer science, I was in 4th or 5th grade back then and little me was already arguing that he should go rather to the CS college because of my love to computers ;) ,but my cousins really happy now so its all fair and in all fairness he and everyone thinks it was a decent decision.
Back during the process of his college and eventually going to ISRO, it wasn't that well known, but then two missions made it really have a spotlight it was before there were movies and the national fame and recognition that it got, before that nobody knew too much of ISRO but then suddenly literally everyone knew what ISRO :)
Also, the papers regarding ISRO if going through the college route is the JEE Mains/Advanced exam. Based on my personal observation, it is like the gakao exam and its a really really soul-sucking exam :-(
Most people who actually top that exam leave the nation anyway and the most focus is on the IIT or rather on prestige rather than passion. It sucks a little because Computer science is treated as prestige rather than passion which hurts people like me who are passionate getting grinded into dust :-(
Indian society and gatherings really feel very prestige/respect focused in many areas to me, though I am not sure if its an Indian phenomenon or not. Respect/comfort/stability seems to mean a lot more in my opinion
Interestingly that's $5 million less than the the movie Interstellar cost to make.
No point, just perspective.
From what I know, its partially because of how taxation structures incentivize research as R&D tax breaks or similar don't particularly exist in India
All of this makes founders more likely to move abroad where such research is more valued which makes even less Indian deep tech startups and successes exist. This creates a vicious cycle.
I would also consider that Indian VC scene as compared to America undervalues quite decently even for B2B or even supposing identical companies and even then, Sequoia and some other American VC firms are still the most valued and I feel as if that given their expertise and contacts (other companies that the VC's have invested in being in America), there would be a slight push towards Europe/America in general. Another argument could very well be that in India CS engineer labour costs much less which is honestly some of the largest expertise for any company.
Though Indian VC scene is thriving and Bangalore is interesting but still Silicon valley is different.
There was a blog post which talked about VC dynamics and VC's value your product not on how much the real value they really see in the project is but rather on how much money you would require. So ironically, projects which require larger budgets/funds for researching, larger salaries to work would then have larger valuations.
I guess Eastern Europe is a bit similar (in the fact that it had a brain drain; although maybe less so since my country joined the EU), but also have a unique challenges, i.e., the EU market is fragmented and the companies need to break into a market by market.
Can they compete with reusable American rockets for $/kg by just building disposable but very cheap rockets?
After all, plenty of other disposable things have outcompeted non disposable versions... Diapers... Pens... Lighters... Vapes...
SpaceX might fail for any number of reasons in the next ten years, but I would bet a lot of money that it won't be because they got outcompeted by Skyroot.
There's another startup trying reusable rockets.
What do you mean by this?
They were founded in NZ by a NZer, they launch from NZ, their employees are NZers. Calling them a US company is equivalent to saying Google is Irish.
Design and manufacturing is in the los angeles region aerospace industry cluster.
It's been a US company for the last 13 years.
https://rocketlabcorp.com/updates/rocket-lab-makes-its-defen...
Earlier this year they acquired a new machining business in Auckland and are expanding capacity at their NZ launch site: https://rocketlabcorp.com/updates/rocket-lab-establishes-new...
They've been an American company for over a decade at this point.
It profiles: Astra, Firefly, Planet Labs, and Rocket Lab
As for the rest of India, you can largely find the root causes of problems by tracing adverse selection effects among the elites that do remain, massive, conflicting vested interests and decades of horrible, incompetent policymaking.
- Low GDP per-capita, offset by immense scale, which means the central government can mobilize massive resources for national projects, but municipal bodies are financially starved (municipal revenues in India are < 1% of total tax collections, for context it's 6% in South Africa and 10% in Brazil). Cities are completely dependent on the state for money, unlike countries where cities control their own property and commercial taxes, so they raise very little on their own, and states have multiple other priorities so cities never get as much money as they need.
- Leading off the previous point - executive power over cities is very fragmented, most authority rests with state chief ministers and state-appointed bureaucrats rather than empowered local mayors, so city planning is subordinate to state-level political priorities. City management itself is divided among uncoordinated state-level bodies (separate agencies for roads, water, power, and transit). There's a lot of accountability voids where something goes wrong and everybody thinks it's a different body's responsibility. The poor coordination also means you'll have things like a road laid on Monday, and on Wednesday the water authority digs it up to fix pipes underneath.
- The Indian constitution guarantees freedom to move and reside anywhere, so it's not legally possible to control rural to urban migration like China did with its Hukou system. E.g. Bangalore adds anywhere from 350k to 600k people a year almost entirely from internal migration. Much faster than housing, transit, and civic utilities can keep up with.
Things are getting better, although slowly and unevenly:
- Mass transit is expanding rapidly
- Door-to-door solid waste collection now reaches roughly 98% of urban wards (tougher than you would think because the unrestricted migration tends to create a lot of ad-hoc unplanned settlements on the outer parts of cities)
- The central government is working on allowing cities to issue municipal bonds to raise their own funds.
- Bangalore now (as of last year) has a single body called the Greater Bangalore Authority that has statutory oversight over previously uncoordinated agencies that handle water, transport, power, transit etc. Other state governments with major cities are watching to see how it plays out, and will likely copy + adapt it to their own major cities based on how it goes.
https://news.ycombinator.com/item?id=48904776
The last bullet point in adithyareddy's comment below here also captures a similar point.
If I were launching my first orbital vehicle and I didn't have a hyper developed space program already, I would want to equip it with something like Starlink so I would be able to communicate with it even when it wasn't in range of my ground station(s).
That makes there be a mathematically optimal number.
Obviously solid rockets can't be relit.
Could that be the use of the 4th stage?
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, inserting a single purpose satellite-like pusher device above the responsibility boundary at the top of second stage and payload satellite and calling it the third stage, or just adding actual third stage above second stage, etc.
Adding more and more stages improve performance per Konstantin Tsiolkovsky's rocket equation, but it'll add risk factors and also obviously add more dead weights in electronics and engines and support equipment, so 2-3 stages is usually the good balance between performance and risk/costs. You can have as many stages as you want if you think you can handle it.
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, but that seems to be the standard with solid fueled rockets.
(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")
There's also the issue that a solid booster must be "fueled" before it reaches the pad, meaning you have ground crew working around a large quantity of explosive material. A Brazilian solid rocket exploded on the launch pad, killing 21 people.[1] Liquid rockets can be made inert until everyone is far away, then loaded with propellant.
A big advantage of solid rockets is that they can be stored for long periods and quickly launched. This is handy for use cases like ICBMs, but not particularly important for commercial launches.
But by definition if you can put something into a 350x350 km low earth orbit (something like 7800m/s total delta V) you could also deliver a re-entering payload from your launch site to any other spot on earth, within the limitations of the inclination you're launching to.
Even if your target doesn't have missile defence systems, any ally of theirs along the route can intercept too.
The missile defense we commonly hear about these days is used against lower speed , shorter range and altitude missiles:
https://en.wikipedia.org/wiki/SM-65_Atlas
There's a reason all modern silo based (and submarine) ICBMs are solids.
Believe it or not, here in 2026, this is incorrect!
Those crazy Russians:
https://en.wikipedia.org/wiki/R-29RMU_Sineva
https://en.wikipedia.org/wiki/R-29RMU2_Lajner
UDMH + nitrogen tetroxide.
I would not want to be a Russian submariner. For all sorts of reasons.
For a proper MAD-based nuclear deterrence, yes, you want to be able to launch a massive retaliation while your enemies' missiles are still in the air. Submarine-launched missiles also require stable storage. But having first-strike capabilities, the ability to wipe out any city in the world in return for a few weeks' planning, seems like something militaries would find valuable.
It isn't because of some purported Gandhian mindset. It's becuase India is in a pacing conflict with China and Pakistan, whereas China is in one with the US and historically the USSR. Assuming the Chagos Archipelago dispute gets resolved in the next decade (India and France backs it's return to Mauritius because Mauritius' police and military leadership are under direct Indian control [0] but the US prefers Chagos remaining under British control because we are closer aligned), India has no need to explicitly publicize ICBM capabilities that extend beyond China or Turkiye.
Additionally, publicly stating India has ICBM capabilities makes it harder to land transnational mining deals [1] because then discussions with Australia, Brazil, Canada, etc adopt a nuclear proliferation dimension as well as placing a target on India's private sector because of SpaceTech and DefenseTech's dual use implications.
[0] - https://thesecretariat.in/article/inside-raisina-hill-nsa-to...
[1] - https://www.ft.com/content/c5868e2f-8d19-4393-93be-2ad726a63...
If I, some rando on the internet, can theorize "that sure looks like it could be turned into a storable icbm that could deliver a nuke to hawaii or Tierra del Fuego or anywhere else on the globe" can make that guess, then any other major world power is likely far ahead of me in analysis.
Also well known that having the institutional knowledge and technical capability to build or adapt something in a fairly short time frame is almost as good as having the thing ready to go.
Exactly. This is the norm.
This is similar to how Japan doesn't have nuclear weapons.
It can be hard when you are blindsided by negativity that seems to come out of nowhere. Hopefully this is helpful to us all https://rss.com/podcasts/the-narrative-networks-podcast/3017...