Elon Musk is at it again. The billionaire behind Tesla and SpaceX is known for his audacious plans, and in October of 2019 he took them one step further, when SpaceX sought permission to launch 30,000 satellites into orbit. That’s on top of the 12,000 satellites they’ve already been given approval for as part of their Starlink mega constellation that aims to beam high speed internet around the globe, starting with service in North America as soon as 2020. For the math inclined among you, that means SpaceX would like permission to launch up to 42,000 satellites into low earth orbit. And the only question I have is: Why? If you were to head over to SpaceX’s Starlink website, you’d see that their main selling point is global connectivity: something that would benefit people in rural areas or in places where current internet service is too expensive or unreliable. And that’s all commendable, since it’d be great if everyone around the globe had access to the internet.
But 42,000 satellites is an extreme amount of high tech hunks of metal to launch into space. For context, right now the UN Office of Outer Space Affairs estimates there are about 4,000 satellites in Low Earth Orbit. So SpaceX alone would like to launch up to 10 times that. The idea is to form a web of satellites whose orbits criss-cross and provide global coverage. It seems like a very expensive proposition, so is there more to this project than just making the world wide web truly world wide? SpaceX is a business, and they wouldn’t do something like this if it couldn’t turn a profit. Despite the project’s estimated minimum price tag of 10 billion dollars, Musk believes it could bring in as much as 30 to 50 billion dollars in revenue each year. Why is it worth so much? It’s all about cutting latency time, or the amount of time it takes information from your computer to reach its destination and come back.
Here on Earth, the preferred way to transmit large amounts of information over long distances is through fiber optic cables. These bundles of glass fibers carry beams of light from one point to another, taking advantage of light’s extreme speed. But because light has to travel through the medium of glass, it doesn’t reach the same top speed it does in a vacuum like in space. In a vacuum, light travels at nearly 300 million meters per second, but bouncing through glass that speed drops to around 204 million meters per second. That adds a few microseconds of latency per kilometer. So sending information through space could save a lot of time, provided it’s done in the right way. For decades we’ve used satellites to send data to remote parts of the world, but typically the ones we use are in geosynchronous orbit, where they appear fixed over one spot in the sky. To achieve that positioning, the satellites have to be in very distant orbits over 35,800 km high.
That means that even using light at its max speed, latency times are around 700 milliseconds. So SpaceX plans on putting its satellites much closer to home, operating at 550 kilometers up. At this altitude it’s impossible for them to stay over one spot— they have to move faster to stay in orbit. Hence the need for so many of them to maintain coverage. But at that distance, a network of satellites passing along information at light’s top speed will have less latency than any fiber optic network longer than 3000 kilometers. And the farther the data has to travel, the more of an advantage a network like Starlink will have over its terrestrial fiber optic counterparts. This high speed link is worth incredible amounts of money to financial markets, where milliseconds of delays can translate to millions of dollars lost as markets shift. Starlink still has a long way to go before its promise can be realized. The satellites will have to be cheap and reliable enough to justify launching thousands, and once they’re up there, they need working autonomous collision avoidance to keep from smashing into other satellites and causing a runaway debris problem.
Astronomers are also warning that so many satellites sending so many radio waves could interfere with ground based optical and radio observations, so SpaceX is working out how to build and operate their satellites in a way that doesn’t affect them. And of course SpaceX isn’t the only company racing towards satellite broadband, with companies like OneWeb and Amazon’s Project Kuiper pursuing similar goals. In fact, that may be why they applied to launch 30,000 more satellites: as a move to box out competition rather than because that’s the demand they anticipate. All-in-all it’s another classic Elon Musk project. It aims high and promises huge returns, and it’s not without its skeptics and dissenters. Will a constellation of satellites connect the world while still keeping the skies clear for science and other spacecraft? We’ll just have to wait and see. Even if the speed information is sent around the world speeds up, a slow wifi router can still bottleneck your system.