Reading this from the comfort of your home, you probably don't think about the huge infrastructure that is behind the internet and allows you to browse this website. Sadly, this infrastructure is not available for half of the population of our planet. Thus, leaving these people offline or with very poor network connectivity, which denies them access to the huge range of opportunities the internet provides.

Moreover, if we look at broadband connection, the kind of connection needed to get decent video streaming quality, 25Mb down 3Mb up. The picture is even worse, in a developed country like the US, 1/3 of the rural population lacks broadband access to the internet.

Starlink, SpaceX's new project aims to solve these problems. Starlink will be a constellation of up to 42.000 satellites that will provide reliable internet access to the whole planet. The only thing the user will need is a relatively inexpensive antenna to connect to the satellites (about 200$). This can sound expensive for prospective users of the service in poor countries, but an antenna could be bought for the whole community and then connection relayed to users using WiFi access points.

I've heard that before

Some may be asking themselves, doesn't that sound a whole lot like satellite internet? That unreliable, crazy expensive service available since the 90s. No, Starlink is completely different from that, let's see why.

When we connect to traditional satellite internet, our packet follows these steps:

1. The packet travels up to the satellite and down to one of our provider's gateways
2. Our provider connects through traditional cable infrastructure to the service we requested
3. The trip is repeated in the reverse order to deliver the response to the user

Traditional internet satellites are placed at a geostationary orbit 33.000 Km above the earth. That is practical because at that orbit, the satellite rotates at the same speed as the earth, so it is always above the same spot. So, the provider just needs one satellite to cover its area of interest.

Such high orbits also bring problems, a signal travelling at the speed of light takes at least 220ms to go up to the satellite and come down (you can do the math, the speed of light is 300.000 km/s). This means the satellite introduces a minimum latency (the time taken for the data to be transmitted) of 440ms to our connection. When we factor in the time from the provider to the service and other usual network delays, the round trip latency goes up to 1 - 1.4s. That's 35 times slower than a cable connection, which makes it unusable for most of the current internet demands. In addition, as these satellites are geostationary, they only get placed in areas where there is a high concentration of customers that can afford the expensive service. Thus, leaving underdeveloped countries out of the question.

Getting up close

Starlink introduces a few innovations to solve the problems of traditional satellite internet. First of all, Starlink satellites orbit at 550 km, cutting down latency to a theoretical minimum of 4ms. Moreover, as Starlink is a constellation of satellites, it transmits packets using lasers between the satellites of the constellation, instead of using the ground cables. So the packet will go up to the closest satellite to the user, transmit in space hopping from satellite to satellite until it reaches the closest one to the service the user is accessing, and then come down.

Connecting through space, makes Starlink even faster than ground Fibre-optic cable for two reasons. Firstly, the speed of light in an optical fibre is 2/3 of the speed of light in vacuum. Secondly, as there are so many satellites, packets in space can be transmitted following a nearly straight-line path, while on the ground they have to follow the available cables. The combination of these improvements makes it better than our ground-based infrastructure. Finally, satellite coverage will be global instead of just focusing on rich countries.

While at the start Starlink may be an expensive service, as it scales up and other competitors deploy their own networks it may be able to provide service to people in underdeveloped countries at competitive prices. Moreover, it will democratise internet access by breaking up current government or company monopolies on ground infrastructure. Thus, bringing down the prices of internet access significantly.

60 Starlink satellites in the SpaceX vehicle before being deployed. Photo by Official SpaceX Photos

It's not all rosy

Although Starlink may spread the internet to every corner of the world in an affordable way, that's not why it was built. The reason why Starlink puts such an emphasis on low latency is high-frequency trading (HFT).

HFT uses algorithms that ingest data in near real time to profit off orders by institutional investors. Let's see an example of that. Imagine a pension fund decides to sell a large quantity of shares of Airbus because it thinks the stock is overpriced. It will have to place small orders to sell the shares in multiple exchanges, as it would be really difficult to find a single investor that wants to buy that many Airbus shares at once. The pension fund will therefore place several orders in the Paris, Frankfurt and Barcelona exchanges that list the Airbus shares. Let's say the sell orders from the pension fund arrive first in the Paris exchange. The high frequency trader will see it and leverage its latency advantage to rapidly buy shares in the other exchanges, so it can sell them at a mark-up to the pension fund. That's why latency matters so much. In HFT, a few microseconds can make the difference between winning or losing millions of dollars. Proof of this is that some banks place their servers as close as possible to stock exchanges to get the minimum latency.

HFT is a very controversial topic that would need a full post to cover, but it has been responsible for some flash crashes and can introduce volatility to the stock market, due to it being controlled by algorithms that can contain bugs. If you want to learn more about it here are a couple of articles that give two different views on the issue. Confused about high-frequency trading? Here's a guide (Against HFT), High Frequency Trading Explained Simply (For HFT)

Loads of space junk

Starlink also introduces some issues that need to be addressed. Having so many satellites on the same orbit, increases the chance triggering the Kessler effect. This happens when a satellite crashes with space debris, breaking into many pieces that continue to orbit at 27.000km/h and that can knock out other satellites in the orbit, creating a cascading effect that leaves the orbit unusable, due to the amount of debris in that orbit. SpaceX has included a collision prevention system on their satellites to try to prevent this.

Finally, astronomers have complained that the reflections caused by Starlink satellites will impact space observation from earth. To solve this, SpaceX will be implementing "sun visors" on the satellites to reduce the effect.

Starlink satellites polluting a long exposure shot. Photo by NSF’s National Optical-Infrared Astronomy Research Laboratory

TLDR: SpaceX's Starlink project has the potential solve the internet access problems of half of the world's population. Whether it will do so will depend on other players entering the market to create competition and bring down cost. Sadly, it is proving to be a difficult business, with Google and Virgin (OneWeb) ditching their projects.

PD: If you reached the end of the post, you could try and find the Starlink satellites that appear in the header photo.