portillo

This is exactly right!

I think that 5M is a high number (at least with the current number of satellites and their architecture), specially if they do not apply data caps.

I would say that 1M customers in the US is a more reasonable figure. If they hit these number, I expect the performance to degrade significantly.

There are multiple pictures of OneWeb´s assembly line in their website, https://onewebsatellites.com/factory/ , including pseudo-blueprints: https://bit.ly/32QSDBS

Still far from what you would expect from a truly automated production line, but it has dedicated stations that allows workers to assemble multiple satellites in parallel.

A satellite dish does not transmit any information to the satellite. Satellite TV is a pure broadcast system in the forward direction.

Moreover, comparing a parabolic receiver with a phased array is quite unfair. The amount and complexity of the electronics and processing power required is several orders of magnitude different.

Reminds me of OpenLASE: - https://github.com/marcan/openlase - https://www.youtube.com/watch?v=hoWCNKhZCbk

You can get 24/7 connectivity to LEO right now (and 25 years ago too) using TDRSS.

The system costs a fraction of what Starlink will cost, as you only need 3 GEO satellites.

The current satellites do not have crosslinks, and in any case, in their FCC filings SpaceX talks about optical crosslinks, not RF.

I agree, this was the real reason why the project failed. Moreover, it was not clear at all that fractionation would bring any lifecycle costs savings, neither that any of the alleged extra flexibility (and maneuverability, resiliency, maintenability, and other -ilities) would result in any added value for the missions.

Fractionation is very hard,it introduces a lot of complexity in the design and interfaces, and it requires lots of coordination between multiple vendors. Project Ara by Google (a modular cellphone similar to Phoneblocks) also vouched for this idea of fractionation (and in fact was also led by Paul Ermenko) and was also cancelled.

Sure, operated manually by a bunch of people with PhDs.

I think so too. In addition, they seem to have regenerative payloads on-board (otherwise I don't get how they get ~20Gbps/sat with a single Ka-band antenna), so they need to do full decoding + encoding on the satellite. Not sure how fast that can be done, but it will add some latency ms probably.

Hi Mark,

Thanks for your reply. I agree with you, using user-terminals is extremely challenging, especially from a link-budget perspective. You cannot pump enough data to make it worth it. For the gateways, my main concern is that the Ka-band spectrum would have to be shared between user-data and "inter-satellite" data.

Finally, I think that the use-case your described for those latency-sensitive customers is going to be hard to pull off, mainly because of link-availability concerns. There are too many "passes" through the atmosphere to guarantee the availability numbers that a user of such a service requires (99.5%?). Rain in any of these links might cause an outage or a re-route (causing too high jitter). Plus, it would be extremely difficult to have signals traveling from one continent to another.

These analyses are quite optimistic as they only consider propagation delay.

Moreover, the idea of using user-terminals/gateways as ground-relays to bounce signals up-and-down is quite impractical, since you would be greatly reducing the capacity available to satellites on those "intermediate" satellite.

That is not the round trip time, it's the one-way delay. Also, processing time can be significant in satellite networks. Finally, given the current architecture of SpaceX without crosslinks, the total RTT will be ~30 ms + processing time + whatever is the RTT of the backbone network they deliver the traffic to.

It will not work. Their use case is low data rate applications. It's one of those case where you pick 2 among high number of users, high bandwidth, and low gain user terminals.

> to a self-described expert, who unfortunately didn't provide a ton of context),

Are you questioning the expertise of Tim Farrar? If that is the case, you couldn't be more wrong. Check his blog and you will see he has been doing this thing for more than 20 years...

Also, lynk will never be able to provide enough bandwidth to deliver internet connectivity. It is envisioned to be used for short messages.

In their original FCC filing, they were estimating 386 kg per satellite. The ones launched in May were 227 kg each, and those last month 260 kg (they added the Ka-band antennas).

I am not sure how much heavier will the satellites be when they integrate the ISLs (if they do), but I believe that in any case they will be under 330 kg.

I am the author of the slides/paper. The analysis was done with the best data available at the time, but I am interested in knowing what parameters you think are off / have changed substantially since then.

I can say that the mass and volume of the satellites has changed quite a lot, and therefore the number of rocket launches required is pretty off in the paper. But I have not seen much info to invalidate the rest of results.

NSR has some public estimates here: https://www.nsr.com/leo-survival-of-the-fittestor-the-smarte...

NSR estimates for SpaceX are higher than what SpaceX claims (Gwynne Shotwell just claimed some Morgan Stanley estimates of $1M launch + $1M to be way off [1]), but still, I wouldn't expect them to be able to launch the 4,409 satellites of their intial design for less than $10B. And it's not clear that they will be able to raise such amount of money without a clear path towards profitability.

I agree with the shaklee3, Tim's blog is very legit. As full disclosure, I am the first author of the MIT study he mentioned, and the more I look into LEO mega-constellations, the more skeptical I become.

[1] https://twitter.com/thesheetztweetz/status/11877454453611806...

It will only have lower latency when they have the inter-satellite links. Until then, they will have the latency of fiber PLUS the RTT from the user terminal - satellite - gateway path.

I would bet that there will be no more than 1,200 (if they raise the money needed to launch and manufacture that many).

And I would also bet that even in an 8 year time-horizon, they will not launch 12,000 satellites for Starlink because simply, there will be no market for so much capacity. In my opinion, we are heading towards an Iridium, Teledesic, Globalstar 2.0 scenario.

This is, in my opinion, kind of a myth. In the markets where the average revenue per user is high (Europe, USA, Canada, Australia) there is already (or there will be very shortly when Viasat3 is fully launched) high-speed reliable Internet connectivity through GEO satellites. And yes, the latency is huge and there are data-caps (which are pretty low if you want to binge-watch Netflix). But I am not sure that LEO constellations will be able to compete with GEO vHTS in price (not to mention the huge challenge of getting the price of the phase array user terminals cheap enough), so I am skeptical they will be able to capture a significant fraction of the market share.

In the rest of the world, the ARPU is so low that it's hard to have a viable business model for broadband satellite connectivity (for all orbits GEO, MEO, or LEO). Furthermore, 90% of the population is currently covered by 3G/4G networks, so I would argue that for most of the 3.5 billion people currently unconnected, the issue is not infrastructure (but other factors such as affordability, relevance, or readiness). Finally, populations in those countries connect largely using mobile broadband (i.e., in Southeast Asia 75% of the population only use cellphone to access the Internet), so I think that fixed-broadband will have a limited impact in those places. (Maybe they can get a higher share of the cellphone tower backhauling market, but it will depend on the price per Mbps/month they can offer to MNOs).

It was ordered by the "Juzgado Central de Instrucción número 6" of the "Audiencia Nacional" which is presided by Manuel Maria Garcia-Castellon. The police cannot request taking-down a website without a judicial order.

> So from far away, I would question the neutrality of the Centre d'Studis d'Opinió.

They are the "Department of Statistics" of Catalonia, and they are controlled by the local government (pro-independence), so i am not sure why would they be biased to report lower support than the actual one. Our Constitution does not consider secession of part of a territory. To hold a referendum, they will have to change the constitution first, which is unlikely to happen in the short term.

Also, I am not sure that a referèndum is the best way to settle this conflict. I think that other options that can gather the support of more than 50% of the population would offer a better solution. (i.e., how do you build a new country when half of the population feels strongly about it?)

I hope that ends up happening, it will be a bigger innovation than all these constellations!!

I don't think it will happen in the next 3 years though. I think that most of the manufacturers are focusing on the high-end market, and first terminals will be in the thousands of dolars.

My PhD research is on how to use space and aerial networks to serve the unconnected and undeserved. I have been studying these networks (and things like Google's loon, mmwave, etc) for the last 4 years. I have simulated these networks in detail, assessed their capabilities, and ran a lot of financials myself.

According to my analyses, there needs to be a disruptive change in how we receive broadband Internet to close the business case (that's why I keep talking about Displacing ISPs). The unconnected and undeserved broadband market plays great in the US and Canada, but in the rest of the world, there is simply not such a market. At best, you are going to try to provide backhauk for a cell phone network or some other kind of access point. The whole 3B of unconnected people rethoric is very slim. Those people can afford to pay very little every month for connectivity, so it's very hard to make money out of it (even to offset your marginal costs).

In terms of performance, there are diminishing returns on each extra satellite that you launch. The ones already up there are already satisfying a lot of the demand, so each newly launched satellite is active for a shorter and shorter percentage of time.

Starlink is a (in my opinion) very oversized system. I do not think they will launch the full 4,409 constellation (as it stands today), and I am pretty confident they will not launch a 30,000 satellite constellation.

Finally, LEO networks are not the most cost effective space networks. GEO HTS and MEO networks have lower CAPEX/GB.

Well, you are saying that you have a fixed bitrate per beam to divide among all the users in the area. The bigger the area the more users. And once you reach saturation, that's it. Also, if there is a very populate city inside the beam footprint, you are only going to be able to serve to a very limited amount of people in there.

I also like Tim's idea here:

https://twitter.com/TMFAssociates/status/1183436364974419968

You are right, maybe I should have said where the sub-100$/kg comes from.

In the first Starlink launch, with 60 satellites of ~230 kg each, the cost of launch was ~$30M (considering that the "retail price" of a Falcon 9 launch is $60M, I guess that half the cost if a good assumption). Thus, the cost per kg was $30M / (60 * 230 kg) ~ $2,000/kg. I just don't see how they are going to achieve a x10 reduction in cost, even considering reusability, larger masses, etc, etc.

You could provide home broadband using a wireless, mobile-network like system if you wanted to.

It is not happening because it's very difficult to do that with the spectrum allocated for mobile services. A network of towers can provide higher capacity densities than what SpaceX's 30k satellite systems will be able to.

In big cities, they will fall very sort of the capacity required. The current 4,409 satellite proposal has beams of ~700 Mbps, and each of those covers a surface larger than the whole NYC metropolitan area. The capacity scales linearly with the number of satellites in line-of-sight (LoS). Right now, with the 4,409 satellite system you can have ~40 satellites in LoS, so they can provide ~28 Gbps of throughput to the whole city. Even with 30k satellites, they will only be able to provide ~196 Gbps. That is not enough to offer any uncapped data plan.

For the source, see [1]. "The coverage gap– those living outside of areas covered by mobile broadband networks4–continues to decrease below the 1 billion threshold and now stands at 750 million people. Since 2014 the gap has more than halved, from 24% to 10% of the global population." It's actually 90% covered by 3G and 4G.

Regarding the costs, I am not sure where your 60k/sat is coming form. Currently, launch costs for SpaceX are in the millions (60 commercially, let's say 30 millions cost), and they are launching 60 satellites at a time, so at least 500k/sat.

I am not sure that they will be able to cut the launch costs by a factor of 10, even considering resusability, larger launch capacity, etc, etc.

[1] https://www.gsma.com/mobilefordevelopment/wp-content/uploads...