I got a couple of questions from friends about what exactly Starlink is. Here’s a summary. (I think I posted one of these before, but here it is again 🙂
Starlink is a new kind of high-speed satellite internet service from the rocket company SpaceX.
I’ll fist explain what’s wrong with traditional satellite internet and then I’ll share how SpaceX is solving those problems to provide a service that’s competitive with terrestrial internet.
Traditional satellite internet has a few problems that make it slow for the price. First, the satellites are super high up there. They sit about 22,000 miles up where their speed matches the Earth’s rotation. This is how they seem to always be in the same place in the sky and your dish can point to that one spot and not have to have a motor to track the satellite’s movement. But there’s a big downside to having a satellite so high up. They’re really far away. Even though the signal moves at the speed of light, light has a finite speed, and 22,000 miles means at least half a second round trip. This makes the internet feel “laggy”.
The second problem with traditional satellite is that the technology is often kind of old. Historically it cost a lot of money and took a lot of time to build these communication satellites. This means that the traditional providers don’t upgrade their satellites very often with the latest and greatest technology so even though technically they could be faster, they’re often relying on years-old tech that’s just not up to speed.
The third problem with traditional satellites is that the service providers over-subscribe. They simply have too many people connecting to a single satellite which has limited bandwidth and so all the customers suffer as a result. They can get away with this because there’s little to no competition for rural broadband. When it’s your only option, you’ll take it even though it’s not great.
Starlink tries to solve all three of these problems and it does so on the back of SpaceX’s very affordable rocket launch service. Where every other major rocket launch company throws their rockets away with each launch, SpaceX lands its boosters and re-flies them many times so their costs are ridiculously low (perhaps as low as 10-20% the cost of a new rocket.)
What can you do with super-low-cost rocket launches? Well, you can put a lot of modern satellites up quickly and affordably and replace them with new ones as soon as you’ve got something better. SpaceX has a massive assembly line that builds small, cheap, flat-packed satellites, and then they rely on those used rockets to launch the satellites in batches of 60 at a time. Starlink currently has about 1,000 satellites orbiting Earth and will have many, many thousands more in just a few years.
The Starlink satellites fly at very low altitudes, about 340 miles up. This has two implications. First, round trip time to the satellite is dramatically reduced compared to those flying at 22,000 miles. SpaceX plans on sub-20ms latency so your internet won’t feel laggy. (As we speak they’re directing the the whole constellation to lower itself a bit to further improve latency with a target of 16ms.)
The second implication of flying this low is that the satellites are moving really fast to maintain orbit. This means they don’t sit in one place in the sky but rather move across the sky pretty quickly . And that means you need a lot of them in order for one to be visible overhead at all times and you also need an antenna that can track their movement.
As I mentioned earlier, SpaceX already has over 1,000 orbiting satellites on their way to many thousands, even tens of thousands. But what to do about needing an antenna that steers to follow the moving satellite. SpaceX solved this problem not with mechanical steering but with something called a phased array antenna.
A phased array is a collection of many small antennas and when power is supplied to each one in just the right amount, their individual signals interfere with or reinforce each other in just such a way as to bend or steer the beam. This is digital steering, not mechanical steering so the user’s terminal can be a simple solid state device and doesn’t need a motor running all the time which would wear out and consume a lot of power.
OK, so that’s how Starlink addresses the traditional satellite problem of latency. What about the other two problems? The second problem with traditional satellite internet was stale technology. Because Starlink can launch satellites so cheaply, and because they build small, cheap satellites at scale, they can iterate their designs and put up improved versions of the satellites as soon as their engineers have made those improvements. So the constellation is always up to date with the latest and greatest technology while the earlier generations of satellites are simply de-orbited. (Note: they burn up fully on de-orbit.) A Starlink satellite is only expected to be useful for a few years. They’re almost disposable.
Then there’s the oversubscriber problem. This has more to do with business than with technology but both play a part. Traditional satellite internet services only have a few satellites to support all of their users and those satellites can be on 5 year old technology. SpaceX’s Starlink has thousands of satellites to support their users and those satellites are becoming more and more capable every year. So, as long as SpaceX is careful with not selling service to too many people in a geographic area (which is why they’re targeting rural users and not city dwellers right now) and they meet their target for how many satellites they want to have up there, then bandwidth should be good for all of their subscribers.
So, Starlink is a constellation of thousands of cheap, low-flying satellites and a technologically advanced user terminal/antenna that today can provide about 150 Mbit/s internet speeds with 20-30ms latency for $99/month and in a few years should be gigabit with even better latency.
Most of this is made possible by SpaceX’s innovation in rocket re-usability.
Right now, SpaceX is beta testing their constellation with over 10,000 customers. I’ve just joined that program. If you’re interested, you can try to get into the beta program or reserve your spot for when they become generally available at https://starlink.com