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Comment by gibybo | Hacker News Reader

People aren't generally using a 1 gbps connection at 100% capacity 100% of the time. If we assume customers use an average of 1 TB of data per month and the time they use it is pretty spread out (seems reasonable since they are going to be spread out accross timezones eventually), you can serve about 6 million customers with 800 satelites @ 23 GBPS, and with 4400 @ 23 GBPS you could do ~33 million.

Admittedly these numbers are all best case scenarios (except maybe the 1 TB average, that's probably generous), but even if you divide by 2 it's a decent number of people.

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Using the 4400 example. People pay ~20$ per month for under 10GB cellular data. So 100GB for 150 million globally people globally seems viable. If that 150 million is paying 15$ per month that's 30 billion per year. Optionally, I suspect a few customers would pay a lot more for a larger monthly cap.

The issue is the antenna needs to be around 2 foot by 2 foot.

But, with autonomous cars people may want significant bandwidth in there cars. An hour or two of video a day seems reasonable especially if they can cache popular content.

Honestly, if they can get the price down this could be very profitable.

"People pay ~20$ per month for under 10GB cellular data."

It depends on a country. Where I live, you can get unlimited 4G Internet for 15-30 eur/month (depending on a provider).

This might primarily be for their autonomous vehicles. It makes sense for them not to rely on 3rd party for cost/reliability reasons.

Heck, the leap in positioning accuracy 4.4k satellites would make gps obsolete. Civilian gps accuracy is low enough that you cannot distinguish between lanes on a highway.

Do you need to track/tune them all at the same time, or can you mux between them? 12 channel receivers used to be common.

Edit: Maybe this has some answers: http://electronics.stackexchange.com/questions/11884/how-man...

Still. What's the cost of deploying 800 sattelites vs cost of fiber infrastructure for 6 million people?

It depends on how far apart those 6 million people are and how much infrastructure is already in place.

Since satellites handle most worst-case distance scenarios with respect to fiber, it is reasonable to assume a connection spanning the world (including access to remote areas)

So long as it breaks even, SpaceX comes out ahead, since they're deploying the sats, and learning how to build the sats in a mass produced way.

+ economies of launch scale.

In cities, the fiber, or even some form of local wireless, is much cheaper. However, in more rural areas the satellite system can well end up the cheaper choice.

The interesting part is what building 4425 satellites does to the economics of making satellites. Right now, most satellites are one-offs, or at most made in a series of 10 or so, handmade to exact specifications for maximum reliability and built for 25+ year lifetimes. This fleet is meant to be mass-produced and built to last a much shorter time, 5-10 years at most. I am very interested in just how low can they drive the cost of making a single satellite.

"This fleet is meant to be mass-produced and built to last a much shorter time, 5-10 years at most. I am very interested in just how low can they drive the cost of making a single satellite."

One of the best points in the discussion. This has potential to produce side-effects more valuable than whatever they were attempting to do. As in, they can fail in their overall goal but a ton of great things would come from success in this part.

Interesting when you say "However, in more rural areas the satellite system can well end up the cheaper choice."

You mean a satellite system can well end up your ONLY choice. If you're rural there are no choices besides dial up and satellite. Satellite is a reseller selling hughesnet.

I think it might be comparable.

It's really hard to estimate since we don't know their satellite costs, but $100 million per satellite (launched) is probably a good starting point. That ends up being $13k capital cost per customer. If they can borrow capital at 5% or less, that works out to ~$55/month.

But if they succeed with reusable rockets (and it sure looks like they will), they can probably drop the launch cost from $60m to $10m in the near term. If we assume the satellite still costs $40m, that still cuts the total cost in half to ~$27/month @ 5%. Maybe they can mass produce these satellites and get them to $10-20m each, which would reduce it to more like $15/month.

Again all these numbers are pretty rough/best case scenarios, but even if we multiply them by 10 we could be looking at 1 gbps connections for $150-500/month. That could be cheaper than fiber infrastructure in a lot of places and still immensely useful in applications where fiber isn't possible (in a car, plane, or boat). That's also assuming 1 TB/customer. In many cases you may just buy the bandwidth in smaller increments at $1-10/gigabyte which is a few orders of magnitude cheaper than current satellite internet and comparable with LTE cell coverage.

They're only going for 51 orbital planes and it's fairly simple to spread out many satellites from a single launch if they're in the same orbital plane. And a Falcon 9 can carry 20,000 kg to orbit whereas each satellite is pretty light. Some people on /r/spacex calculated that the binding constraint is actually the volume of the Falcon 9 payload fairing and they'll be able to launch 20-25 satellites at a go. And I would expect that mass produced satellites to be far cheaper on the margin than bespoke ones. All of which is to say that it's probably more like $10 million per satellite launched.

Depends where those 6 million people live. I've heard internet in Kilimanjaro is not that great...

So they'll be able to get awesome bandwidth (by today's standards, anyway), but the monthly plan is might be a little pricey.

Pretty much yes. It's not about giving $30/month broadband to remote parts of the globe...

But isn't it still cheaper to lay fiber cables?

For example, 23*4400 = 101Tbps, but I guess many of the satellites will end up above water, so maybe around 60Tbps. One cable by google did that for 300mil$ [1]

Maybe it is good for last mile connectivity, which is probably a good target, but only for less populated areas where LTE isn't available.

[1] https://www.extremetech.com/internet/231074-googles-faster-u...

Yeah the cost advantage is entirely in last mile connectivity. It doesn't really make sense to compare the cost of a single cable to the cost of the end customer getting a connection. LTE is a much better comparison, but I think the cost will actually be pretty similar or cheaper than LTE (see my other post for napkin math) and cover a lot of areas/applications that LTE can't.

Maybe it's a lot quicker - Google Fiber has been taking forever. Not that rocket science is easy, but it's probably a lot quicker than striking the earth.

Laying fiber isn't going to get your Tesla connected.

Interesting idea but wouldn't a satellite to car connection be pretty unreliable?

Since the line of sight would often have things in the way. I'm assuming trees, bridges, and being in a garage would interfere with it.

Yet GPS works.

AIUI, GPS isn't a connection. It's broadcast, one-way communication. Also, I assume the information transferred is much lower, not much more than time and position, plus redundancy to handle things like interruptions due to landscape.

Well, there's going to be 800 of the suckers. There are only about 33 GPS satellites. Although 700 miles is lowish orbit, it's still above the horizon over 2000 miles away.

Wow. I read this comment and thought, "This has to be bullshit." But lo and behold, the core satellite 'constellation' is only 24 satellites[1]. That's mega impressive.

https://www.faa.gov/about/office_org/headquarters_offices/at...

And they transmit with about 50 watts.

Look up the connection between Einstein's general relativity and GPS accuracy for more fun. Especially early on in its deployment.

That's actually a myth, since the GPS satellites all experience a similar relativistic time skew.

http://www.alternativephysics.org/book/GPSmythology.htm

"The presence of Special and General Relativity effects has no bearing on the accuracy of GPS operation. In summary, it wouldn’t matter whether clocks aboard GPS satellites ran faster or slower than Earth’s clocks or even changed their speed each day. Just so long as the satellites’ clocks remained synchronised with each other and the time-difference relative Earth’s clocks didn’t become too large, GPS receivers would continue to calculate their correct position."

That page constructs its own argument and then deconstructs it. It doesn't actually disprove the OP's statement.

The reason that GR and SR have "no bearing" is because they've already been designed into the system...

From "Understanding the NAVSTAR" 2nd Edition, by Tom Logsdon ( one of the designers of the system ) the time-dilation is compensated through:

1. Off-setting the clock ticking-rate during manufacture of each satellite.

2. Applying a unique onboard corrective factor according to the eccentricity ( egg-shapedness ) of each satellite's current orbit. The latter is correction is constantly recalculated for each satellite.

Without these corrections against relativistic effects the accuracy would suffer by 14 nm after 24 hours ( without tick-offsetting ) and 100 feet or so per day due to orbital eccentricity.

That's the one. There's pages one can get from Google with some of the data and illustrations if they can't get the book. It tripped me out when I found out they had to design relativity into it.

I knew I shouldn't have questioned you so flippantly... Lesson learned.

Feel free to question as Im a human acting on incomplete information like the rest. ;) Just don't assume or read in too much as that can get you. Happened to me plenty here, too, haha.

Well, GPS is more like radio, you only listen to the broadcast, you don't talk back.

But this is more like cellular access points. You have a private channel.

You don't establish a communication channel with GPS. You merely listen to the broadcast.

Like a radio tower can service an entire town, but you need many many cellular access points.

I used to have a sat phone (Thuraya) and it was pretty reliable if you were outside. They don't work well inside buildings.

You'll get around that in your home by having the satellite module thing up on your roof and a cable to your wifi router.

What I don't understand about this though is the number of frequencies available to connect to all these satellites and how it might extend to ~300 million people (let alone a billion potentially).

I think they focus a beam on each user in turn and so don't need different frequencies.

Can't lay fiber to the entire planet for $300mil

They're presumably aiming for some amount of economy of scale by using their own rocketry service. Dollar for dollar comparison doesn't account for the fact that they're investing some of that cost into further rocketry development.

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