Starlink is effectively a point to point connection with each satellite. There is no technical reason they can’t have 1 billion customers with a large enough network and the right hardware.
The issue is economic. Target 1 customer per square mile and most of the orbit over land is useful, target 100,000 customers per square mile and most satellites are only beneficial over megacities like NYC.
Due to the short lifespan of individual satellites they can adjust to market forces and new technology fairly rapidly. If for example China lets them in the economics around density change significantly.
Directionality of antennas/electronically steered beams (off axis gain is not zero on the satellite or the terminal) and the relatively large bandwidth involved in these links imposes a limit that you'll hit even with an unlimited number of satellites. Calculating that limit is tricky but I don't think it's practical to cover urban areas for the reasons the parent brings up... cellular networks rely heavily on short effective range; the minimum achievable spot size for LEO satellites is still much larger than a typical urban LTE cell, and the terminal has the same problem of spot size in orbit being quite large.
The spot size is proportional to the phased array antenna size, right? Could SpaceX just keep scaling up their phased array antennas on the satellites as Starship reduces launch cost?
Antenna size is a different one. They're orbiting low enough that atmospheric effects become a real issue. See the deployment in February[1] where they lost ~40 of the 49 satellites in a launch batch, because a Geomagnetic storm increased the atmospheric density at their initial parking orbit, overwhelming the ability for their control system to maintain orbit.
So, yeah, they could then scale up the control system, too - but that makes them even heavier, increases fuel expenditure, reduces lifetime, etc.
The antenna array is parallel to the ground, so scaling it up has a minimal impact on drag.
It increases mass, sure, but an increased mass to drag area ratio is usually considered a good thing (you'll be needing a better rocket to launch it tho).
It's not always perfectly edge on, and it requires a control system to keep it oriented that way.
This is why from the linked article:
> The satellites were then placed in a protective "safe mode" and commanded to fly edge-on "like a sheet of paper" to minimize drag effects as the company worked with the U.S. Space Force and the company LeoLabs to track them with ground-based radar, it added.
The v2 satellites they're testing out to launch on starship are in fact scaled up. The v1.5 they're launching now are larger than the originals which is why they've not launched 60 starlink satellites on a single falcon 9 launch in sometime.
I thought they start at about 250 km after launch and then boost up to around 400 km. They don't have very powerful thrusters or gyros so they couldn't boost faster then they fell out of orbit.
It seems that they are far safer once they have boosted up into operational orbit - that's why only the recently launched Starlinks fell back to earth.
This is the standard way of showing the performance of antennas - it shows the varying amount of power that is sent out from the antenna in different directions. Note that (a) it doesn't roll off immediately outside the target zone (usually the 3dB threshold as shown here) and (b) there is measurable power in completely off-axis directions. In fact the tighter you beam steer, the more lobes you get in weird places.
Both of these mean that you can't just parcel up physical space into perfect beam spots and just keep adding satellites. There are all sorts of things you can do to help as you go up, but it gets harder and harder.
That's true, but assuming maximum possible density both the sender and receiver should be using directional antenna on top of this the closest satellite gets the strongest signal simply due to distance. That distance effect becomes less meaningful as the density increases but stays relevant for practical networks.
Both ends of the starling link are already using directional antennas. The difference in power die to distance is already pretty irrelevant - the satellite is 400km up and we're talking about offsets of 10km on the ground. The 400km part of that is far more dominant making the power difference to the 'next satellite over' be very small.
“Both ends of the starlink are already using directional antennas” Sure, but it’s critical to understand the associated benefits when doing this kind of analysis.
If you’re talking average 10km separation on the ground that would mean stupid high constilation densities. A lower densities it’s more meaningful.
PS: I got to 1 billion customers assuming different hardware and more satellites not just more satellites. The only way 100,000 customers “works” is a none viable and lower bandwidth per customer business model, but the goal was to illustrate a point. Space X is aiming for an economic sweet spot, not the outer edge of what’s technically possible.
I don't follow your economic logic. Are you saying 100,000 customers need 100,000 different satellites which is too many to be used efficiently on the rest of their orbits?
That was in reference to the capacity to handle X customers per square mile not total. If you want to average 100,000 customers per square mile over a wide area you need a fuckton of satellites over that area.
Basically a network that handles 1 customer per square mile might in theory have say 40 million customers worldwide eventually. A network capable of handling 10 people per square mile might cost 10x as much, but only increase that to say 120 million because some areas have less than 10 potential customers per square mile. Increasing that to say 100 or even 100,000 people per square mile would vastly increase the cost, but you hit heavy diminishing returns with a lower percentage of areas reaching those densities and many people with better internet options than starlink or simply can’t afford the service.
The issue is economic. Target 1 customer per square mile and most of the orbit over land is useful, target 100,000 customers per square mile and most satellites are only beneficial over megacities like NYC.
Due to the short lifespan of individual satellites they can adjust to market forces and new technology fairly rapidly. If for example China lets them in the economics around density change significantly.