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SpaceX FCC Application for over 4000 Internet Satellites (fcc.gov)
508 points by paulsutter on Nov 17, 2016 | hide | past | web | favorite | 206 comments

You gotta love the genius of a guy whose rocket company gets to practice for their Mars launch by sending up a bunch of satellites (powered by the solar panels he makes) to assemble a new worldwide wireless internet company, in order to provide ubiquitous connectivity for his autonomous car business.

I am about 99.9% certain that these will not be powered by consumer grade Si solar cells in special panels/encapsulation. Satellites typically use triple junction GaAs cells (>30% efficient) which are rated for space:



Spectrolab is owned by Boeing.

Typically, but SpaceX has made rather a habit of ignoring expensive space-grade components in favour of consumer-grade ones they test themselves for a fraction of the cost. I guess we'll see.

SpaceX has made a habit of doing that only for their rockets, not telecommunications satellites, and only when it makes sense. Their biggest cost savings are in operations, manufacturing processes, and their engines because there really isn't much room to skimp on anything else.

Even at a cost of $10k per kg it makes very little sense to use 50% less efficient solar panels to save a few thousand, especially when the superior technology is also far better tested in space. It makes sense to use an Android instead of a $100k RAD hardened processor if your entire CubeSAT barely costs that much. Since most satellites cost a minimum of a million each, very few can afford the risk to save money on parts (and if you're mass producing thousands of them you can get really cheap germanium panels).

Cumulative Wh produced per sunlight/night cycle (remember these are in LEO and constantly passing in and out of the earth's shadow) per kilogram of solar panel is also important, when the satellites will be quite small.

You want the greatest possible power capability in the smallest and lightest package, and right now the way to do that is a triple or quadruple junction GaAs type PV cell with a concentrator lens in front of it. Efficiencies range from 32 to 40%, vs 22.5% efficiency for the very best monocrystalline Si PV cells.

This is all absolutely true - and would apply in any typical circumstance - but I'm not sure this is typical.

These aren't geostationary - they're low earth orbit. This means several things:

- cheap to launch - and to deorbit.

- lots of erosion compared to GEO - LEO is like being in a mild sandblaster while occasionally being shot at by rifles and howitzers.

Taking those two alone into account, you either end up building for durability or for disposability.

When you're dealing with a fleet of 4000 and your speciality/the thing you want to practice is heavy lift to LEO/MEO, you are absolutely talking about a disposable fleet where you expect daily failures and replacements. Having mass production facilities at your fingertips can't hurt.

Which is why they'd likely go for the cheaper tech that they have very low cost access to, even if it costs about the same after launch costs. Also, it would be more profitable for the collective enterprises than outsourcing such a component to a third party. Think about it - spend the money with a competitor, or at the gas station. I know which I'd do.

So - despite obvious truths re GaAs, my money is on them using their own Si cells.

I think you're vastly overestimating the significance of satellite material cost and underestimating how much larger assembly, testing, and operating costs are going to be. Four thousand satellites sounds like a lot and it is in the single unit volume world of aerospace, but it's not even close to enough to reach the kind of economy of scale everyone thinks about when they hear the phrase mass manufacturing. The cost of parts will be tiny compared to the cost of assembly and testing. To give you some perspective, you can get a 80mmx80mm 28% efficient GaAs solar cell for about $600 on Alibaba and the equivalent Si cell is about $6 with about 20% efficiency. At the volumes needed for a constellation of thousands, from a reputable vendor like Spectrolab, the price difference is in the 50-100x range so assuming a $1 Si cell the equivalent GaAs cell will cost $50.

Do you see how small the difference is in absolute terms? That means that only a few hours of labor per solar cell or 100g of launched payload mean the difference between a 50x and 1x difference. Two GaAs panels ($100) will requires tens of grams less support structure than the three Si panels producing the same power ($3) so already the extra launch cost (at $5k per kg, assuming free payload support structure) for the Si panels is eating away at their benefit. Each solar cell will need hours of inspection and testing by people paid $25+/hr so even if each extra Si cell and support structure costs nothing to launch, the final cost once fully assembled, installed, and tested will be in the range of $1k-10k per solar cell.

Especially at the scale of disposable satellites, GaAs is likely to be cheaper, more efficient, and free more volume and mass in the satellite design. 4000 satellites worth of Si solar cells would be the equivalent of a few dozen decent sized residential installs so it would be a drop in the bucket for SolarCity. I don't think keeping such small scale business in-house is much of an advantage, especially when there are many other suppliers with lots of experience in using solar cells in space.

>lots of erosion compared to GEO - LEO is like being in a mild sandblaster while occasionally being shot at by rifles and howitzers.

At 1100 km the debris population is relatively sparse. https://en.wikipedia.org/wiki/File:Spacedebris_upd_2011.jpg

But in lower parts of LEO you still have meaningful amounts of atmosphere(!).

Sure, you can use commercial parts in LEO for the processor. That is very common in the small satellite world already. But I really doubt they would run Android. Why not just bare Linux, possibly with the PREEMPT_RT patchset, or another RTOS? Especially since attitude control is a real-time problem.

I was just providing an illustrative example, the exact implementation details are irrelevant. Android phones have been used as the central processors for a number of CubeSAT missions so without any circuit design you can get a sub $500 CPU kit which is much faster and cheaper than a $100k RAD CPU (and available at any electronics store unlike single board CPU modules).

Telecom satellites already require tons of specialised integrated circuits because general purpose CPUs are too complex and power hungry for the amount of bandwidth the satellites process. This SpaceX constellation will certainly have custom designed electronics, even if they don't use any rad hardened ICs.

> Why not just bare Linux, possibly with the PREEMPT_RT patchset

That'd be a really bad idea. Linux is too complex to trust, and lacks WCET making it unsuitable for hard realtime.

There's open source options, but Linux isn't among them. I'd look at seL4 for this purpose.

SpaceX already runs Linux on their rockets; apparently near-real-time is good enough for that purpose.

Yes, I was saying why would you use Android instead of just bare Linux (as in Yocto). I doubt you will be writing an ADCS application in Java using a GUI.

Also, I think the Falcon 9 uses VxWorks for at least some of its realtime control: http://blogs.windriver.com/vxworks/2010/12/vxworks-helping-c...

http://lwn.net/Articles/540368/ doesn't mention VxWorks.

Looks like Dragon runs VxWorks, see under Flight Software.


Can anyone who works at SpaceX chime in?

That article also says

> One of the areas they focus on is scheduler performance. They do not have hard realtime requirements, but do care about wakeup latencies, he said.

It sounds like their hard real time controls are on non-Linux OSs.

Do SpaceX build telecommunications satellites?

Not yet. It's worth noting that the OneWeb constellation of small satellites is going to be produced in a new factory, because existing ones aren't set up for assembly-line production:



This means that existing companies that build telecom satellites need to do it a new way for these constellations of lots of small satellites.

>> Do SpaceX build telecommunications satellites?

They have a satellite division which has a bunch of people designing things, but they have not launched their own yet. They have also made known their intention of fielding a global internet service via a large constellation of satellites. This application would be a step toward that goal.

Question: whenever SpaceX launches a thing to the ISS - do they have an experimental payload along for the ride to "test some shit out"?

See this picture of the Dragon spacecraft's panels: http://www.space.com/images/i/000/017/802/i02/spacex-dragon-...

They are very clearly Sunpower C60 or similar, a high end mono-Si cell.

I am a bit skeptical about the economics too, but apparently it works for SpaceX.

Yeah, you'd think that if they were really optimizing those panels then they'd trim them down to cover the surface with no gaps. This is pretty common in solar racing, for example.


I know for a fact key Dragon solar array team members at SpaceX have extensive solar car racing experience, so if they're not trimming cells for maximum coverage, it's for a reason. (I would suspect the benefit doesn't outweigh the cost and/or risk.)

It's common for many types of cells, but much more difficult for Sunpower cells. Instead of having top contacts, Sunpower cells have a fine array of contacts on the bottom [1]. Cutting this without creating shorts or defects is quite difficult. It would be better to have Sunpower custom make them.

Given SpaceX deadlines it's possible that they just ran out of time for this optimization.

[1] https://sc03.alicdn.com/kf/HTB1XRXrHVXXXXXeaXXXq6xXFXXXM/3-5...

It's worth noting that the SpaceX satellites only have a mission length of 5-7 years, and the Spectrolab solar panels are built to last for a typical 15 length mission (from the link you provided). Perhaps they will opt for (presumably) cheaper components given the shorter lifetime.

15 years is the nominal design lifetime for an "insured" geostationary telecom satellite... When SES or Intelsat launches a new 3500 to 6000 kilogram sized satellite it's insured by a third party company. There's specialists in this. I'd say it's much more likely the SpaceX program will be self-insured so they can take a risk with satellite bus technology and other tech that has never been flown before.

How this will affect their choice of PV cells I don't know.

With 4000 satellites it's likely that their approach to each satellite will be smaller and much less redundancy:

If a traditional 5000 kg geostationary telecom satellite can be compared in analogy to a big, expensive, 4U, quad socket xeon server that has multiply redundant everything.

These small satellites might be much more like a facebook open compute blade server, 1+0 and redundant nothing, but much, much cheaper to build and with a software architecture tolerant of entire nodes failing and disappearing from the network.

It costs them a lot less per kg to lift to orbit, maybe they're just throwing more panel area at the problem? They're claiming 22.8% efficiency for their earthbound panels so that's only a ~50% increase in panel weight.

More panels means more atmospheric drag in LEO. This leads to a shorter lifespan of the satellite.

Maybe they're equipping them all with EM drives? :P

I believe efficiency is the smallest of problems with sending stuff into space

Henry J. Kaiser also did it all. Kaiser Steel. Kaiser Motors. Kaiser Permanente (the cement company, not the hospital company). Kaiser Shipbuilding. Kaiser Gypsum. All gone now.

While the entities might be transient, the progress they deliver is permanent.

Musk might not care if Tesla and SpaceX disappear if electric vehicle mobility and affordable transport to Mars is achieved. They are a means to an end.

I'm sure he cares quite deeply about the legacy of his companies, but his core goals, as stated, transcend the current organizations.

He has said multiple times that he thought the likelihood of success for each of Tesla and SpaceX was less than 10 percent, but that was ok, because even in failure, they would 'move the ball forward' on sustainable energy and making humanity a multi-planetary species.

Well, sure, but he also made the hospital company, and that has thrived. I would think if Musk's ventures all go to plan, only SpaceX will be left at the end of it all.

Kaiser Motors is still producing Jeeps as a division of Chrysler.

Kaiser Soze is still out there

Did a search for that. Cheeky.

I love the way he's basically a Bond villain, but nice.

Actually I think the main motivation for this is just to make money, which will then be used to fund things like a Mars mission.

I've seen two sorts of that kind of founder: some are just excellent and create 20 businesses each of which would be impressive on its own. And profitable.

The other: vast networks of companies all dependent on each other. When any one of them gets in trouble, it all comes falling down like a house of cards. And the chance of none of them getting into trouble? (1 - 0.<failure rate>)^<# of businesses>. That gets very small, very fast.

Lesson: never ever make a decision for business <b> because you also own business <a>. Too many people going from millionaire status to personal bancrupcy, at just about the moment where they're too old to start fresh, yet too young to coast.

>Lesson: never ever make a decision for business <b> because you also own business <a>

Shouldn't the lesson be, "don't allow any singular company to become a single point of failure?"

> Shouldn't the lesson be, "don't allow any singular company to become a single point of failure?"

Yes, but that requires more detailed analysis.

It is a better lesson though. Plenty of small to medium businesses fail when their main supplier or something goes under. For a small restaurant this could be as simple as making sure that you have two sources of that special berry (or whatever) you put in your signature dish.

...in order to provide ubiquitous connectivity for his autonomous car business.

This seems like a pretty foolish way to do that. Mobile data over ground-based cellular systems is rapidly becoming a commodity, and at least in the areas of the world where Teslas will be sold, it's essentially ubiquitous. Why in the world would it be worth setting up and maintaining a massive satellite network just to cover the .001% of driver miles spent far enough away from a tower?

Single network that works anywhere in the world? Why not?

It will be a very disruptive business if he can pull it off

Don't forget, they can launch on used rockets for a fraction of the cost. This will also help them to prove the reliability of those used rockets. Mass produced satellites are perfect for that.

So from the Reddit discussion it seems like 200 launches is about a fair guess for the total deployment of this system. It seems like a perfect way to derisk the notion of reusable launch systems while providing a native-to-SpaceX revenue stream (orbital internet provision).

Assuming that they can achieve the success rates they've been aiming for, demonstrating lowered risk and cost through their own deployments will provide about the best advertisement you could possibly imagine. Waiting for organic outside demand to fill the launch roster to the same point would take time that Musk clearly does not want to waste. It seems to be a Keynesian approach to the slightly Chicken/Egg problem of commercial space.

Isn't the launch roster way beyond full already? http://www.spacex.com/missions

I don't mean that it's full from a financial perspective, but full in an argument-ending "this is the way of the future" sense.

Edit: There are ≈80 missions listed on the link there, 200 launches for their own missions would provide ample opportunity to derisk their customers by reusing launch vehicles beyond their currently marketable mileage and proving their safety (I can imagine that one would want some pretty steep discounts for a rocket that's been used 5 times given current success rates).

Also im-proving the safety by getting tons of experience on what works and what breaks, while only risking some of your own hardware.

I definitely agree with you on this point. More launches means less failures per n launches.

Seems like a great mission profile to build a reliability track record before taking human cargo too.

Consistent small profit launches, then as the accident %'s decrease design an ultra low risk human module and start space tourism for real

> Keynesian approach

Please explain.

Spacex would essentially subsidize their own market by making this constellation since it would reduce their own cost per launch vehicle if they used veteran vessels to get their satellites to orbit. It's basically the same idea as a country going into debt to generate demand.

Edit: https://en.m.wikipedia.org/wiki/Keynesian_economics

To me, this seems closer to Arrow's Learning by Doing theory. He had the quite intuitive idea that unit costs fall with total historic output and found some empirical evidence for this with statistics from world war 2 factories. The future benefits here are supply-side (productivity) related and often captured by the specific producer.

Keynes' ideas have been adapted to a range of different forms, but are more about circumstances where the economy is in a deep recession and there is some restriction preventing the economy from utilising all its resources. Here debt financed spending may have demand-side benefits by stimulating yet more demand. This only works at the aggregate economy level, so Elon would have to launch a lot of satellites to benefit from it!

>> This only works at the aggregate economy level, so Elon would have to launch a lot of satellites to benefit from it!

To be fair he's talking about tripling the number of satellites in service with his constellation alone. Within the industry spacex would become the primary supplier and the primary consumer of rocket launches.

I hadn't heard of Arrows learning by doing but that makes sense as well for this discussion.

Coming soon: Elon Prime

Pay 40k a year and get unlimited SpaceX Internet, a Tesla w/ free charging, and a complimentary flight/weekend stay at Solar City Space Hotel.

Who's in?

Honestly, I don't think I'd blink an eye at signing up for that. Space hotel trip alone is worth that!

In fact, that makes me seriously think about the ITS for earth orbit activities. Add a nice big docking port to connect it to a space station, and you've got yourself a relatively cheap reusable vehicle to fly a whole mess of people into LEO.

Virgin Galactic is charging 250k for their "some minutes in weightlessness" ride...

Clearly thats a a stepping onto something better... isn't it.

I mean the planes in the beginning could charge high rates for just flying someone in a circle, but today planes need to be fast, reliable, on time all while being cheap enough that most Americans can afford them.

Something erks me about how that all sounds VERY Facebook/Google -ish?

One organisation that provides our transportation, internet (which itself is gaming, information, communication, business, etc.), energy, and basically every facet of our lives. Google and Facebook are already trying to get closer to that...

Yep, we're back with conglomerates as we had them until a few decades ago. But I don't think this will last long. In a decade or so people will realize that specialized business earn more money and will force them to split up.

I think that it is the natural state of trying to build out a completely new product line (electric cars). They have to build out basically all of the infrastructure themselves at first (quality charging stations, power production to keep the utilities from overcharging their customers, batteries to vastly increase the supply, etc).

As the market matures, some of these businesses might be spun off.

Heck that's quite a deal on an MS or MX 100D lease.

And of course after that, Prime Plus which includes a lease on solar panels and home batteries.

Is there some kind of music service?

pay 40k per year to shop at the company store.

These are stepping stones to the future, they are not the future.

I'm waiting for: Optimus Prime

I'm late to this thread and very disappointed in the HN crowd that nobody has mentioned any of these things.

OneWeb is trying to do the same thing and already has rights to the spectrum from the ITU. They are using Arianespace to launch and Airbus build their spacecraft. It's possible this whole application is a ploy to disrupt Arianespace since SpaceX is upset about not getting a massive launch contract.


Commercial satellite constellations do not have a great track record. Iridium and GlobalStar tried to do phone networks and both went bankrupt. GlobalStar was backed by Qualcomm and Iridium by Motorola. Though they both have complete, functioning constellations. Look at GSAT and IRDM to see how well they are doing post bankruptcy.

Teledesic tried to do the same thing in the 90s and was backed by Bill Gates. It didn't go anywhere.

Tren Griffin, the 4th employee at Teledesic, has a good write up of it with lessons learned. May be able to see if anything has changed that may make these new efforts work where others failed.


"You probably have heard the story about the chicken being involved in breakfast because she laid an egg but that the pig was committed to breakfast since he supplied the bacon. Investors are like the chicken, but startup up employees are like the pig." I liked this quote... perfect way to describe the startup-investor relationship.

Thanks for that. That was an excellent post. As someone who has worked in the space industry, this quote is so true: "They [big aerospace contractors] liked the idea of PhDs assembling massive satellites in clean rooms out of custom parts since it created a barrier to entry."

Also Australian (Israeli) company Sky and Space (ASX:SAS) is launching 3 nanosats in May as proof of concept and have a tie in with Virgin.

My bet is that the "pizza box" phased array rooftop antenna will evolve into a complete base-station. We know it has a multi-element RF front-end feeding in to massively parallel software defined radio (SDR). Likely available in PoE or wireless variants (solar+batteries+wifi; imagine the MIMO with 100 antenna elements!).

SDR is quite interesting because it can track moving satellites, and do simultaneous multipath reconstruction of multiple terrestrial broadcast signals -- digital tlevision, FM/AM/satellite radio, shortwave, etc. No antenna pointing needed, as it's all done in software. After demodulating the carrier the video and audio content is streamed on a local web page available to computers/phones/tablets on the LAN. Existing TVs can be supported via an HDMI or analog (VGA/composite/3.5mm) stick w an RF remote.

Optional (or one-time software unlock?) on-board storage for multimedia time-shifting and distributed CDN caching (reducing bandwidth and latency by keeping commonly served duplicate files like js libraries locally). Having a local server also lets them do fun things in the future like transparent LZMA compression, optional ad/telemetry/malware blocking, data pre-caching, smart shared HTTP caching, etc.

The inclusion of on-board storage allows data to be sloshed around to best utilize the terrestrial spectrum (broadcast content) and satellite spectrum (multicast content). It's much like Tesla batteries allow energy to be sloshed around to best utilize distributed solar and the utility grid.

With proper RF front-end design, support for the diversity of global broadcast standards can added through OTA software updates via satellite. This simplifies hardware into a single "world" model with regional software variants.

Easy install, especially with the wireless version (mount on pole, erect, securely fasten, done). Broadcast signal reach and convenience (any device or TV) that beats the pants off of any OTA antenna out there. Convenient access to terrestrial broadcast content w time-shifting takes some of the load from streaming services, so it's a strategic move and not just a "gee wiz" feature they got cheap because of SDR.

At $200-300 for the equipment and $50/mo for internet, with a good multimedia time shifting UI, SpaceX would cream every rural data provider out there.

Anyway, just the idle dreams of an internet user living in a rural satellite "data desert"...

I've worked with phased array flat panel antennas used for geostationary Ku and Ka band two way satellite access.

Phased array flat panel antennas cannot be purely software steered sufficiently to track a low earth orbit satellite from horizon to horizon. It's not good enough to just put a flat panel phased array facing straight up, you won't have enough gain aimed in the direction where the satellite actually is at any given moment. Assuming a CPE device that measures 1.5'x1.5' to 2'x2' in size, it will still need a motorized azimuth and elevation stepper motor system (or equivalent) to track a LEO satellite.

If you're trying to do multi-Mbps data to/from a satellite in bands >10GHz (and probably >18GHz), the path loss through the atmosphere and RF parameters mean that you want as much gain as possible... This is why the most economical solutions for high capacity two way satellite through geostationary transponder capacity involve 1.8 to 3.0 meter size dish antennas. Gain is important. Gain and enough signal over noise ratio that you can do higher order QAMs and not spend half your bitrate on FEC.

You could, I suppose, if the antenna system was cheap enough and large enough build a non moving, cone or pyramid shaped antenna covered in phase array segments that could maintain a high bandwidth connection in the >10GHz bands to a moving LEO satellite. But it would be pretty large.

edit: for those who are curious and want to see an example of a parabolic (steered) use for moving satellite comms:



there is also an israeli company which is a competitor to mitsubishi in this space. and a few others.

if you watch the weekly FCC filings for new satellite equipment licenses, there's a lot of MELCO antennas flying around on top of mid and large sized jet aircraft.

Thanks, great comment.

Mark my words, SpaceX is quietly working toward nothing less than a revolution in global data infrastructure, just as Tesla is working to accelerate a revolution in global energy infrastructure. Sneaking in some software, onboard storage, putting them on all Tesla cars, mesh networking the terrestrial base stations with MIMO links, etc.

Cars suddenly become a global peer-to-peer mesh sneakernet. It would be fun if Tesla distributed data via "pulses" between passing cars... (signed high resolution maps? deep learning connectomes? the latest Netflix original series? :D)

>Phased array flat panel antennas cannot be purely software steered sufficiently to track a low earth orbit satellite from horizon to horizon.

Righto. SpaceX plans to steer the beam down to 40° from the horizon. This also minimized path losses.

Drawing from the SpaceX filing: http://i.imgur.com/7zOZ7kr.png

>All Ku-band downlink spot beams on each SpaceX satellite are independently steerable over the full field of view of the Earth. However, user terminals at the customers’ premises communicate only with satellites at an elevation angle of at least 40 degrees. Consequently, as shown in Figure A.3.1-1 below, each satellite operating at an altitude of 1,150 km will provide service only up to 40.46 degrees away from boresight (nadir), covering an area of about 3.5 million square kilometers (1,060 km radius)

source: Figure A.3.1-1 on pp6 of the FCC technical information document, currently 404, via /u/SkywayCheerios




> SpaceX is quietly working toward nothing less than a revolution in global data infrastructure

I mean, that's a really cool 40,000 ft view idea and all, but global data infrastructure is made up of things like the Hibernia Atlantic cable, its several dozen cousins of post-2000 transatlantic and transpacific cables with DWDM terminals on both ends, and cool things like 100, 200, 400Gbps per wavelength coherent QPSK/16QAM DWDM terminals. And major terrestrial traffic exchange points of existing Internet infrastructure where ISPs put $150,000 core routers (example: 60 Hudson, NAP of the Americas, Telehouse Docklands, Otemachi Building in Tokyo, One Wilshire, 350 E. Cermak, etc).

Satellite traffic is a pretty tiny drop in the bucket compared to terrestrial backbone infrastructure. It's a truly admirable goal to bring affordable broadband to really impossible to reach locations via satellite. On the other hand there are a lot of emerging terrestrial WISP technologies and PTP microwave technologies that can be used in rural areas to provide bandwidth without the need to pipe it up into space and back. It's a lot cheaper to establish a tower site on top of a mountain, even if you need to bulldoze a road to the top, and spend $30,000 on routers and PTP/PTMP radio gear.

In some of the areas of the rural western US where my network engineering job touches, there are WISPs which are rapidly eating into the customer base of people who are (rightfully so) dissatisfied with highly oversubscribed consumer grade VSAT satellite systems.

In the end there will be a combination of many things. The next generation of high capacity Ka-band geostationary satellites (ViaSat-2, etc) are a lot higher capacity. Services like o3b allow ISPs to buy a dedicated 1:1 high capacity pipe to places that can't be reached by PTP microwave and are uneconomical to reach by submarine or terrestrial fiber (example, all of o3b's new pacific island nation state customers). There's traditional geostationary c and ku band capacity from SES, Eutelsat, Intelsat, AsiaSat, russian companies, etc. And of course terrestrial fiber. You don't need a huge amount of money to run singlemode these days, assuming aerial wood poles and a mostly rural area, you need two guys, a bucket truck and about $10,000 worth of tools.

Completely agree on WISPs. I think SpaceX will be pursuing mesh networking too.

Could an OTA update (and repointing 90°) turn a satellite terminal into an auto/calibrating point-to-point MIMO link?

>global data infrastructure is made up of things like the Hibernia Atlantic cable

Surprisingly the stated primary goal of the SpaceX constellation is actually to compete with long-distance fiber backhauls. Their sell for satellite backhaul is that it's lower latency (no need to avoid continents, 50% faster speed of light, fewer hops) and works everywhere.

Giving global gigabit internet to rural areas and ~10% of urban customers (with the rest on fiber) is only a bonus. :)

Most of what we know about the plan comes from this video. Timestamp is to the start of the juicy bits. https://www.youtube.com/watch?v=AHeZHyOnsm4&t=2m10s

IMHO the shannon limit and basic laws of RF/path loss and channel capacity say that satellite is not a true competitor to backbone links by singlemode fiber. For the equivalent of "last mile" services, yes, but not as a replacement for laying fiber between points A and B.

The entire data throughput capacity of a current generation, 5500 kilogram, geostationary Ka-band satellite that costs $185 million to build and launch is much, much less than the 80 channel x 100 Gbps per channel DWDM system you can run on two strands of 9/125 singlemode fiber. And vastly less than the 144, 288 or 864 strand count fiber cable you would see laid between two cities by a carrier-of-carriers operator like Zayo these days.

It is fabulous to see more competition for high priced monthly-leased transport kHz/MHz from geostationary satellite operators. O3b was an amazing thing (and still is). More competition is good. But it's a pipe dream to say that satellite backhaul will ever be preferable to fiber carrying N x 10GbE circuits or a 100GbE circuit...



I really appreciate your comments. This stuff needs to be out there more.

I expect crosslinks and backhaul up/down will be multipath laser w adaptive optics, not RF. As you say the physics demands it.

At 1100 km altitude each satellite has vacuum line-of-site to any other satellite within 6000 km (ground track). By "skipping" satellites you gain extra bandwidth capacity and reduce latency. Easy to route around damage, with no single point of failure (unlike fiber in certain areas). Obviously this will all be optimized with network and timing analysis to hell and back, just like fiber.

LEO has advantages of lower distance traveled, dramatically lower attenuation, faster speed of light, fewer hops, no cable breaks to fix, and no actual cable to run (which the expensive part of fiber, after all). You just build the repeaters, and exploit the fact that the exosphere is really transparent.

Musk, a guy who knows his physics and math, predicts in that youtube video that they'll ultimately do "more than half" of all long distance traffic. He also acknowledges that they have to 'skate to where the puck will be' re: telecommunication technology or they'll end up dead like innumerable predecessors. It's an interesting watch.

> IMHO the shannon limit and basic laws of RF/path loss and channel capacity say that satellite is not a true competitor to backbone links by singlemode fiber. For the equivalent of "last mile" services, yes, but not as a replacement for laying fiber between points A and B.

The filing states they'll be using free space optics / lasers between satellites. The Ka/Ku links are only for the initial uplink and downlink.

> But it's a pipe dream to say that satellite backhaul will ever be preferable to fiber carrying N x 10GbE circuits or a 100GbE circuit...

It is not a pipe dream. Free space optics in... well space, have a 50% propagation latency advantage vs terrestrial fiber. This helps equalize things somewhat.

> The Ka/Ku links are only for the initial uplink and downlink.

Then there's a huge bottleneck, if the links from the satellite constellation as a whole to the trunk earth stations (not the CPEs) are high capacity Ka-band, there's RF issues with capacity...

It's like if you have a network that's composed of a whole lot of 10GbE backbone links from router to router and your IP transit connection to upstream ISPs/the global v4/v6 routing table goes through one 1000BaseLX link.

No, it's nothing like that. They're talking about highly localized signals via phased arrays on both sides. Additionally you underestimate the capacity of wireless: LTE has no problem doing 30 bits per 1 hz of spectrum. These will run at a lot more than a 1 gbit globally shared last mile.

Keep in mind that you don't really need to compete with fiber if you believe there are enough unserved people. I think his comments were misleading since they probably won't target that market. Another problem with Leo is that the rate of consumption is going up extremely fast on the internet. By the time this launches the total capacity of their system may sound like a lot, but it's spread over all the satellites uniformly. So what do you have to do if you want to double your capacity? You need to launch another 4400. They're essentially going to play a game where they need to keep up launches fairly quickly to go with the rate of internet consumption. I also believe the ground cost will be interesting, especially the user terminal. Typically phased array is so expensive that they'll need to sell it at a loss.

Can it really be faster than fiber? The majority of traffic flows somewhere between Europe, North America, and East Asia. The only part where submarine cables take a detour is Europe<->Asia. US<->Europe and US <-> East Asia are fairly direct. Why is the speed of light faster for satellites than fiber? Even if the satellites are "just" a few hundred kilometers above earth, I can't see how they can have a shorter (and thus faster) way.

That aside, I don't think there's a big market for even lower latency (apart from algo traders). It's bandwidth that matters. You can get stable <150ms round trip times Europe<->East Asia and much shorter times to the US already. Problems with servers on other continents are not due to high latency but low throughput. And as others have pointed out, I don't think a system of satellites can compete with enormous bandwidth a single sea cable can provide.

Does anyone know if there are actual numbers out that show how satellites could transfer even a fraction of what's already travelling below surface?

Rural areas will definitely profit. But while the goal is great (internet for all), it's probably not what pays the bill. Aren't FB/Google's ideas of planes/balloons cheaper?

> Why is the speed of light faster for satellites than fiber?

The speed of light in a medium is slower than the speed of light in vacuum. Fiber commonly propagates at just 200e6 km/sec.

Latency is still important because it's a significant limitation of GEO satcom.

> Does anyone know if there are actual numbers out that show how satellites could transfer even a fraction of what's already travelling below surface?

I'm unaware of any fundamental physical limit that prevent optics in space from matching or exceeding the bandwidth of terrestrial fiber. In terms of engineering the main limit is likely keeping beams in precise alignment.

Thanks for the info with the fibre, thought it was closer to light speed. But for a satellite the signal would also travel through the atmosphere for most of the time, or am I mistaken? Is the speed through air close to the vacuum speed? Otherwise it's probably just 10-20% which I guess would be slower after considering the extra distance?

>Is the speed through air close to the vacuum speed?

Yes, very close. The index of refraction of air is 1.0003, so the speed of light in air is c/1.0003 = 99.97% the speed of light in a vacuum.

The index of refraction in a doped silicon telecommunications fiber core is around 1.4475, so the speed of light is 1/1.4475 = 69.08% the speed of light in a vacuum.

>Otherwise it's probably just 10-20% which I guess would be slower after considering the extra distance?

Undersea fibers have to avoid these things called 'continents.' For long distance hops this makes satellite the fastest system that's physically possible. https://personalpages.manchester.ac.uk/staff/m.dodge/cyberge...

Thanks for the thorough explanation!

Regarding the sea cable length: the continent argument is what I was referring to before. I don't think it's valid as most data flows US<->Asia or US<->Europe. And in both cases the ways are nearly direct. Only Europe<->East Asia has a major detour but I don't know if that warrants a global satellite system. One could still put a cable through russia (actually wondering why that doesn't exist for algo traders, connecting HK and London directly).

WHOOPS, quite the typo there. It's 200e3 km/sec.

True, but submarine cable bandwidth is ridiculously expensive many places. E.g. I know locations where the only local cable operator charge $3000/month for 20Mbps uncontended bandwidth, just because they can. Meanwhile in London even the most extortionate colo-provider I work with charge "only" $250/month for similar quality bandwidth.

Compared to current costs of geostationary dedicated 1:1 capacity (SCPC), 20Mbps full duplex for $3000 is actually an amazingly good deal. If you're in a place in Africa with no fiber access and your only options for a high bandwidth trunk link to the world are c band satellite, you're looking at $25,000+ to build your own 3.0 meter+ sized earth station and then $1800 to $3000 per individual Mbps per month for leased transponder kHz to reach a teleport in France or Germany. This is one of the problems o3b was designed to solve.

yeah, I tried to retrieve the docs from the FCC website and gave up. it appears to be suffering under a severe slashdot effect at the moment.

Ahh, memory lane. LEO satellite internet is one of the subjects that bring me out of lurking.

My first job out of school in 1998 was writing test plans for the antenna pointing and tracking for the Teledesic CPE at Motorola. If I remember right, the initial plan was to have dual steerable dishes inside a pair of radomes—like a pair of Mickey Mouse ears. There was a vague future plan for phased-array antennas, but at the time it wasn't realistic to talk about getting them on roofs at a reasonable price point.

The bigger challenge was the optical intersatellite links; routing traffic between LEO satellites using lasers. The lasers had to track satellites in adjacent planes of the constellation that were traveling in the opposite direction.

It's interesting to see the same general idea for the large constellation come up every few years. If we had actually started building it in 1998, it would've been on a second or maybe even third generation by now.

I'm a little surprised that Apple hasn't given it a try with their billions sitting around. 4K FaceTime, or even just downloading movies or apps instantly would be a selling point for their other hardware.

>The lasers had to track satellites in adjacent planes of the constellation that were traveling in the opposite direction.

Didn't Iridium get around that by having a single "seam" between adjacent oncoming planes which signals don't pass, but for all other adjacencies using crosslinks between planes?

They will not be tracking any one satellite across the sky, only those of the 4000 best suited to that particular site at that particular time.

I'm trying to visualize how it might be set up, from the perspective of the satellite... If you're familiar with how an o3b satellite uses numerous relatively focused high-Ka-band spot beams, I'm imagining each of these 4000 satellites doing something similar but with much smaller spot beams and tighter focus (but also the satellite is smaller, lower power and has smaller antennas so less gain).

The really curious part is how the satellite to ground trunk link will be accomplished, if they're going to try to build something like a modern version of the satellite-to-satellite links that Iridium satellites use, but at much higher capacities, draining traffic from multiple satellites through whichever one happens to be over a gateway earth station at a particular time. Or perhaps the satellites will be able to do that and also opportunistically connect to operator-owned earth stations when they are in LOS.

I hope you don't mind, but I'm interested in talking to you about satellite comms and antennas specifically. You don't have any contact info listed in your profile, but if you'd like to talk you can either hit my personal address listed in my profile, or my planet.com one where my username is patrick.

Those gains would make sense for geostationary satellites, but SpaceX is planning on putting its fleet into LEO, at just a few hundred km. Would you expect the same for that altitude?

Also with 4000 satellites, you probably wouldn't have to track one all the way to the horizon.

It still matters: Try engineering a high capacity (350 to 1000 Mbps) PTP microwave link at a distance of 80 km between two mountaintops... Path loss and channel capacity are real issues to deal with even at distances much shorter than GEO.

Again, not my field of expertise, but worth asking: There's going to be much much more air between two mountains 80km apart than between the surface and 80km altitude. I believe the quantity of air in a column above you at sea level is about equal to 9km of sea-level air. How would that change the problem?

Wouldn't it not need to? Presumably if there are 4000 satellites it wouldn't need to look from horizon to horizon, just approximately up.

It really depends on how they're designing the CPE and network architecture for handoffs from one satellite to another, since from the point of view of a CPE on the ground the satellites are constantly moving. That's kind of opaque right now until more technical details come out, and examples of what the end user terminal hardware might look like (FCC test lab reports, etc).

> SDR is quite interesting because it can track moving satellites, and do simultaneous multipath reconstruction of multiple terrestrial broadcast signals -- digital tlevision, FM/AM/satellite radio, shortwave, etc. No antenna pointing needed, as it's all done in software.

Don't conflate SDR, phased arrays, and MIMO. They're separate things. The latter two can be implemented vi a variety of hardware. State of the art radars tend to use a lot of FPGA's for aperture synthesis, not SDR.

SDR also isn't quite the panacea you're presenting. You can't just slap some magic processor in something and then gain access to huge swaths of spectrum. Even highly advanced UWB phased array apertures are limited to around 10:1 bandwidth. Getting up to and past 1 gigasamples per second is difficult even using the prior mentioned pile of very expensive FPGAs.

You won't be able to pull in everything from ~100mhz signals to 18ghz signals all in one $300 pizza box on your roof. The spacex device will be much more narrowly targeted.

I was thinking about CDN caching too! Imagine this

<script src="https://cdn.spacex.com/js/jQuery-1.8.3.min.js" />

I'm still not sure why they are doing this - I'm in West Africa now, have been through some very poor countries, and every single one has blazing fast 3G connectivity, even in the remote mountain towns.

I'm tethered to 3G, and for all purposes it's as fast as cellular internet I've used anywhere in the world.

It is a little more expensive than most locals really can afford, although they are all checking facebook multiple times per day.....

So I really don't understand this idea of "bring internet to the 3rd world" they have it already.

The plural of anecdote is not "evidence". 4 billion people still lack internet access, and this would drastically increase speeds even for those who already have access to broadband.

Besides, what's with the desperate attempt to slander this endeavor as some kind of misguided moral grandstanding? As far as I can tell, they're not doing this just to bring internet to 3rd world countries, they're doing it to bring better internet to the entire world.

Are those 4 billion people not in range of a cell tower, or are they simply too poor to own or rent a downlink device, be it phone, dongle, or what have you?

I'm sure there's a term for this, but people in the West have this idea that everyone not in the West is a dirty savage living in a mud hut.

Also, you aren't a real rich person until you've "helped the Africa".

> people in the West have this idea that everyone not in the West is a dirty savage living in a mud hut.

Yes, very much. Now I've been moving around for 5 months my eyes are very much open to the reality.

People also thought I would be murdered on day 1, when in fact I have met many, many kind kind friendly people who have welcomed me into their home.

The culture of the West really does teach it's pupils they are the best, and everyone else is crap. The Media further enhances this idea.

I loved when I met a guy in a rural, poor part of Gambia - he said "Oh yeah, my brother lives in Australia. I was there for a few years. I came back here, I like it more".

Africa is not the hell-hole people think it is.

Let's not go too far in the other direction though. I live in Kenya and there are certainly some horrific aspects about living here. However, if you make at least a living wage and learn the rules of engagement you can live quite a balanced life

The SpaceX network is said to be mostly for upstream connections, rather than consumer devices. They want to replace fiber, not cell towers. That's useful just about everywhere.

Even in America there are still pretty big blank spaces on the map.

I live 5-miles outside of a town in Idaho with a state university, and a population of about 30,000 people. Between my house and town, I lose service for 80% of the drive. If I drive from here to the next major population center, I'll only have internet on the state highway for about 40% of the drive. If I make the same drive on back roads, I'll have internet for less than 10% of the drive.

The situation is much the same in much of the rural West.

I should add that the coverage in the parts of rural India I was in last year was far better than rural coverage in the US, surely due in part to population density but it's clear cost is the major hurdle left.

I've said for years, you want fast internet you need to be a rice farmer in China. Because they leapfrogged the copper infrastructure that my local phone company is still depreciating down.

3G becomes saturated quickly as the number of devices on the network increases. I would suspect West Africa would have much less saturation than say New York City.

The discussion on r/spacex:


Interesting note from the Organization section where it shows that Elon's trust owns 54% of outstanding SpaceX shares and over 70% of the voting shares.

Interesting for sure, but not unexpected. You would not entrust your life's work to your shareholders without having overwhelming control.

Unless I'm mistaken, many founders do give up control to their share holders.

Yes, but Elon himself has put $100M into the company, and most of that early. Musk is also popular of the "space travel is scary and there will be accidents; if we put it in the hands of the shareholders it'll get shut down" argument and that's certainly a part of his negotiating position.

For many founders their company being their "life's work" is closer to a delusion, or being generous, a conceit.

yes, but only when forced to do so, Musk hasn't yet had to do that. It's a one time trick when you have a funding crisis.

fcc.gov seems unresponsive, here's a Google webcache link to the HTML application: http://webcache.googleusercontent.com/search?q=cache:3lStj71...

So after blowing up Facebook's Internet-providing satellite, they're going after their own constellation.

I do wonder how this will affect potential customers who would launch communications satellites on SpaceX, but are worried about handing over something proprietary to a competitor.

They have conclusively demonstrated that relying on a small number of satellites in the small number of launches concentrates too much risk. Unfortunately the demonstrated this accidentally blowing up a satellite.

In the long run though, success at scale with a system like this relies on the typically guaranteed losses. A certain percentage of rockets will fail, a certain percentage of satellites will fail, a robust system will be designed to accommodate this.

(Of course, and this is probably the topic of a totally different thread, the tolerance for this must change dramatically when there are people in there.)

there is still the issue of space junk, more satellites, more launches, more mishaps, more junk. And now you have more junk to create more mishaps.

I'm not saying I want more concentration, I'm just saying that the path to de-centralisation is not that clear cut (at there is a threshold were we have to talk about CO2 emissions).

Junk prevention is addressed in the details of the proposal, deliberate deorbiting early, but if not they'll decay nicely. It's still as many satellites as are currently flying at all, but they have considered it.

Yeah I'm really surprised no one else has mentioned the issue of space junk. SpaceX won't be the last company that wants to put thousands of these things into orbit.

Facebook didn't own the satellite, they were simply planning to lease a few of the transponders.

This is true, but I wanted my comment to be short and pithy :P

Not a new competitive risk as this has been Musk's plan for at least two years now. http://www.wsj.com/articles/elon-musks-next-mission-internet...

I imagine this would be a pretty low concern because that would probably violate all sorts of contracts.

As long as spacex is the cheapest taxi then they will have customers. No one sending something precious into orbit is lacking in the legal department. On top of that I think it's fair to say that spacex and Musk have a fairly "good guy" reputation as far as ip goes.

I don't know how concerned these companies are about industrial espionage. I would definitely buy that they were wary of funding a competitor.

I've looked through the reddit post and this and haven't found much discussion regarding the increase in latency that would come with such a service. Does anyone have a general idea of how much slower a round trip is when you count the transmission to the satellites and back? In some multiplayer games a difference of 100ms provides a massive advantage, making it much harder to play competitively on slower connections.

The satellites are on Low Earth Orbit (LEO), so they are much closer to Earth than typical communication satellites. When the distance from ground station is 1000-1500 kilometers up, latency is not a problem. In fact, latency via satellites may be smaller than through fiber as speed of light is greater in vacuum. IIRC in fiber it is something around 0.6c, so a 40 % off from a space-based approach. Also there's probably going to be more switches along a ground-based path than along the satellite-to-satellite route.

Also the fibre doesn't go in a straight line. Undersea, it has to route around continents and the polar ice cap, and sometimes underwater features.

Perfect solution: communicate with neutrinos directly through the earth for a point-to-point absolute minimum latency link.

Brilliant. Only problem is the enormous antenna and the >99.9% ping timeout rate :-)

Depends upon the signal strength?

> it could give people gigabit level access, 20 to 30ms latency, everywhere on Earth





The PSLV launched 20 satellites in one shot and that vehicle is 15M $ per launch. The double digit million cost of SpaceX's reusable rocket isn't much cheaper than that.

Does someone know what orbit these are being launched into and how heavy they are?

You can find launch capacities on Wikipedia. PSLV has a smaller payload and smaller price than F9.

For these satellites, you can find a description of their orbit and a guess at their mass at https://en.wikipedia.org/wiki/SpaceX_satellite_constellation

I work for a company that supports a lot of the satellites launched with PSLV. Most are in high inclination polar orbits. Not only is the PSLV reliable, but it is also very precise in delivery.

Would a hand-held size device be able to connect to these satellites? I'm imagining a mass-manufactured device like a Peek[0] that could be distributed in countries with heavy censorship...


The receivers/Earth stations will be phased array antennas; basically an antenna 'grid'. They won't fit in your pocket, but they will fit on top of your car.

Keep in mind, this system is designed to give the Internet to everyone. The antennas will be small enough to conceal. Since the signals go up instead of across a border, censorship is not an issue.

> Since the signals go up instead of across a border, censorship is not an issue.

That's very short-sighted. The connection terminates somewhere, so the whole path is either (you)-(satellite)-(local ground station)-(ISP in your country) or (you)-(satellite)-(another satellite)-(remote ground station)-(ISP in another country)

Censorship then can happen at:

- the satellite (unlikely, they probably just want to forward packets with minimal power/time use)

- ground stations (great firewall of china style)

- ISP (standard, existing filtering)

- any nation that wants to just shut down the access rather than censor it (wide band, high power noise, send straight to the satellites to kill all communication)

Also, the use of the equipment should be pretty easy to detect if you can afford a few plane trips (maybe even just vans), so nations that don't like the idea can just knock on your door and have a chat about it with you.

You need to get landing rights in all countries you plan to operate your frequency bands in. They cannot simply start transmitting down to any country without previous authorization.

Unless that particular country possesses anti-satellite weaponry, I think you absolutely can. Iran hasn't had much success censoring satellite communications on their soil.




You can't for the most part. Satellites cannot control the signal to the point where it exactly shapes to a country, so if you're able to register it in an adjacent country there's no way to know. Especially with broadcast TV where it's one way. It's illegal to do that, but that's another issue. It's also the reason why you don't see third parties giving access into China.

There are a great many countries where you can get thrown in prison for possession an "unlicensed" Iridium phone, though. Or any other form of two way satellite communications tech. It needs to be cheap enough and ubiquitous enough that hundreds of thousands or millions of people are using it, so that authorities in even a draconian state cannot effectively police or ban it.

Rubber hose cryptography principles.

yeah sure, you can shit on a country's regulations, the response ranges from harmless to starting an open war, with a a few steps like seeking the company's funders extradition, seeking redress in international arbitrage, blocus etc.

And the US allows its companies to ignore most of the possible responses.

I imagine Musk could get even more than the already generous US government protection if he puts the base stations on US soil (I.e. all traffic in NSA reach)

Jamming of satellite signals in the middle east has gotten pretty bad. You have to lease spectrum and the country from which you are leasing it has control of that spectrum.

Furthermore, nation-state censorship only has to make reaching censored services more difficult for the average person. They specifically throttle home internet connections but leave businesses alone.

>They won't fit in your pocket, but they will fit on top of your car.

I think I can glimpse what Musk long-term vision is for "connected cars..."

Satellite is pretty much perfect. One provider works globally (vs dozens of mobile proviers), coverage is near 100% everywhere, and mass broadcast signals (like firmware updates and SDC neural connectomes) can be cached locally on the satellite, conserving uplink bandwidth.

The last time this system was discussed they mentioned needing a pizza-sized dish.

I will be really surprised if, due to the laws of physics and the gain required to achieve reasonably dense modulation/code rates, the antenna is smaller than 18 inches... Maybe like the size of an extra-large pizza box, phased array aimed upwards.

Currently paying US$60 a month for land based internet in NZ and a friend pays $160 for the crappy satellite equivelent. Several million subscribers would not be unfeasable and provide a pretty massive income stream

Add another 8 million or so from Australia

Lots of folks outside the cities in America too. I've heard estimates between 10-30 million.

Makes me think: by the time we get to Mars, Mars will have Internet (and GPS etc).

I wonder if a distributed model would work for telephone service in Southeast Asia (which still has lots of 2G in rural areas), if individuals could offer hotspots / base stations with uplinks to these satellites.

Edit: change Uber-like to distributed. Side comment, lots of Uber drivers buy cars. Uber even helps finance cars.

I don't see the connection to Uber's model, unless you mean Franchise, but I doubt people already have the satellite-wifi transponder like drivers already had cars.

Does SpaceX have any concerns about the Kessler Syndrome [0] or any plans to mitigate it?

[0] https://en.wikipedia.org/wiki/Kessler_syndrome

Of course they do, it's a well-known problem for the satellite industry. From the technical addendum:

> Each satellite in the SpaceX System is designed for a useful lifetime of five to seven years. SpaceX intends to dispose of satellites through atmospheric reentry at end of life. As suggested by the Commission,50 SpaceX intends to comply with Section 4.6 and 4.7 of NASA Technical Standard 8719.14A with respect to this reentry process. In particular, SpaceX anticipates that its satellites will reenter the Earth’s atmosphere within approximately one year after completion of their mission – much sooner than the international standard of 25 years. After the mission is complete, the spacecraft (regardless of operational altitude) will be moved to a 1,075 km circular orbit in its operational inclination, then gradually lower perigee until the propellant is exhausted, achieving a perigee of at most 300 km. After all propellant is consumed, the spacecraft will be reoriented to maximize the vehicle’s total cross-sectional area, a configuration also stable in the direction of aerodynamic drag. Finally, the spacecraft will begin to passivate itself by de-spinning reaction wheels and drawing batteries down to a safe level and powering down. Over the following months, the denser atmosphere will gradually lower the satellite’s perigee until its eventual atmospheric demise.


> "for a useful lifetime of five to seven years"

Isn't that a relatively low lifetime for so many satellites? Doesn't that mean they'll need to make a lot of launches just to keep the fleet operational?

This plan is obviously predicated on viable first stage reuse. Estimates vary (and I'm sure even SpaceX doesn't know what the eventual number would be), but it's conceivable that their per-launch cost would be in the low double digit millions. These are also relatively small satellites, so you can pack quite a few of them on a dedicated launch, as well as sending one or more uphill as secondary payloads for launches that have useful trajectories.

Yes. They are going for a very different model compared to "traditional" comsats. Instead of launching very heavy, very expensive birds that need to last for 10-20 years (to justify the huge development and launch costs), they want to launch cheap and light satellites that can be replaced much more quickly.

As someone stated above, this all hinges on first stage reuse proving to be viable. If a customer buys a flight and they recover and reuse the booster, it's almost a "free" flight for them.

They're building a Redundant Array of Inexpensive Satellites.

Depends on how they do it. The lifetime may be low because it doesn't carry much fuel. But if it's small enough they can launch dozens at a time.

I think the idea in the first place is to lower the per unit cost. Then spending millions more for longer life doesn't make as much sense.

My best guess is that they're actually going to use the ITS first stage for this. If that's true, we may see as many as 500 of these launched in one go, with a reusable first stage.

I think Kessler syndrome is still likely to happen despite the best intentions and efforts of all players involved. a 1,000km circular orbit is very, very stable, so if something goes wrong and the satellite doesn't deorbit itself properly, it will be there a very long time. If there are on average 4000 of these at a time and only .1% of them malfunction in this way, that's still 4 per year.

Well, eventually we will get Kessler syndrome at some low altitude orbit. But at a rate of 4 satellites per year, we can stay complacent for a couple of millennia.

But yeah, expect this number to grow fast as more people do stuff like that. It will be a problem eventually.

Interesting. Thanks!

Things in very low earth orbit will re-enter on their own, if left unattended, from atmospheric drag.... At orbits of 450-600 km or less the lifetime of any satellite is very much finite. Satellites in much higher (like the MEO O3b satellites) will not re-enter due to atmosphere drag even on a 500+ year time scale.

In my opinion, the Kessler Syndrome, or a Carrington Event, are the two most underrated yet likely causes of TEOTWAWKI.

Why would a Kessler cascade be so devastating? Most of our comsats and all our GPS satellites are above LEO.

It would completely fuck up the viability of all earth-sciences and imagery satellites (Hello google earth, google maps, bing maps, etc) which mostly orbit as low as reasonably possible and in 90 degree inclined polar orbits.

It would also kill Iridium (either the current generation of satellites, or the next generation which will be in generally the same orbital configuration) because it depends on low earth orbit, highly inclined polar orbit satellites. Iridium is incredibly important to maritime users and aircraft users, in addition to its massive US DoD use.

What would you say the probability of something going wrong and leading to Kessler syndrome is, if we have 4k more (or even 10-20k more) satellites?

I'm sure SpaceX isn't the only player thinking of adding a lot of cheap satellites in orbit

But would it prevent launching any more?

The End Of The World As We Know It. (I had to google. Interestingly, my Mac’s dictionary has TEOTWAWKI as an alias for “Survivalism”.)

AIFF: And I feel fineeeee!!

For the uninitiated (incld. myelf...), "The end of the world as we know it."

What is the FCCs regulatory remit when it comes to satellites? Presumably the application only affects satellites with a US footprint, and only if broadcasting on regulated frequencies?

Any idea what amount of bandwidth they'll have put together?

My guess is nothing less than 1 Giga bit per second.

Am on satellite internet. When it works, it's kinda okay. 25mbps down are possible and sometimes achieved. On a Friday evening though, the shared medium hits hard. Last week an 'aptitude update' took an entire business day.

So, yeah, I'm gonna assume people who're by every definition smarter than me aren't going to try this kind of 'meh' technology for their own Google Fiber like plans. Ground based RF networks make a lot more sense imho.

The SpaceX plan puts the satellites in low earth orbit, much closer than the geosynchronous satellites you can connect to now. That lowers latency into the 25-30ms range. There will also be many more of them, and presumably they are being built with the understanding they will need to support the bandwidth requirements of the Netflix-era of internet usage.

Thanks for clearing that up. Latency is another of these things currently, pings below 800ms are a rarity for me. Very noticeable and pretty annoying.

I'm not presuming I know better than a bunch of SpaceX engineers.

Would anyone be surprised if this is (in part) responsible for the shift in focus for Google Fiber? Why would Google invest Billions for a small portion of coverage while Elon is busy building an ISP for the whole world? Elon and Larry are friends, and Elon has talked about using LEO satellites for internet access before.

Musk says that 90% of connectivity in cities will be fiber, only 10% satellite. Fiber works great in high density areas.

So, would this be consumer-facing internet, or would SpaceX be subletting capacity on their network for various providers to offer "space internet"?

This has been mentioned before in the context of municipalities building/maintaining fiber infrastructure and subletting to ISPs.

Musk's 4.4k strong array of communications satellites in LEO becomes a weapon (think Lex Luthor) if you can point the full transmit power of a bunch of them at a single point (think MIMO).

How much microwave energy do you need to put on a watermelon to make it pop?

Where is the satellite quantity for this application? I cant find it.

This got me to think if it is possible to create a super giant Wireless Network, With Satellites, and Microwave tower on ground as well as Whitespace Super WiFi / LTE mesh network.

SpaceX might target phone business also besides internet

protip: buy rural real estate in good locations before this goes live.

That real estate already has coverage by Verizon, AT&T and probably a couple of WISPs.

Source: I live in such a place.

Between this, self-driving Teslas, and Tesla solar panels and battery storage, absolutely.

The problem with satellite Internet is the uplink and downlink speeds.

Can't wait for global internet!!!!

... as opposed to local internet that we have now?

Maybe they should start with a reliable launch system.

If they'll be launching thousands of satellites, I expect the marginal cost of replacing one launch to be lower than what most satellite makers could manage. And then, reliability has a cost of its own.

Have you calculated the optimum?

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