Science

How SpaceX's Satellite Internet Will Actually Work

Tonight, the company is launching the next big chunk of its Starlink constellation to bring gaming-quality internet to every corner of Earth.
falcon 9 taking off into space
Photograph: Space X

If you haven’t heard, there’s a new space race underway. The goal is to bring the “other 3 billion” people who lack internet access online using massive constellations of broadband satellites that number in the thousands. Leading the pack are SpaceX’s Starlink and OneWeb, former collaborators whose bid to bring the net to orbit has turned into a rivalry that plays out in FCC petitions and spicy Twitter exchanges. The tension is understandable given the stakes. For OneWeb, the global adoption of space-based internet is critical to the company’s existence; for SpaceX, it is key to funding Elon Musk’s Mars ambitions.

Both companies put their first satellites into orbit last year, but 2020 is when things will get serious. In February, OneWeb will launch a batch of 34 internet satellites to bring its total to 40, and more launches are expected later in the year. SpaceX already has 122 Starlink satellites in orbit and plans to do as many as 24 Starlink launches this year with 60 satellites per batch—starting today.

So far both SpaceX and OneWeb have used their internet satellites only for testing (or tweeting, in Musk’s case), but SpaceX says it will have enough birds in the air to start providing internet service by the summer. OneWeb says its constellation will offer limited service by the end of the year.

Space-based internet is nothing new, of course. Companies like Viasat, HughesNet, and Iridium have been raining bits and bytes on Earth for decades. But the next generation of internet satellites promises to be far faster than its predecessors and to make memes accessible anywhere on the planet by rethinking extraterrestrial networking.

No matter who you’re getting satellite internet from, the basics of the system are the same. A user sends packets of data from an antenna at their home toward a satellite, which relays these packets to a ground station back on Earth. At this point, the spacefaring data travels along the global internet’s fiber optic cables just like any other data. Once it reaches its destination, say a Google cloud server, a new packet of data is sent back to the ground station, beamed up to the satellite, and then beamed back to the user’s home.

The two largest satellite internet providers in the US, HughesNet and Viasat, both use satellites the size of a car to deliver their service. They sit in geostationary orbit, which means they always stay in the same position relative to the surface of the Earth and have hundreds of gigabits per second of network capacity. The advantage of this approach is that a single satellite can provide internet services for an entire continent. The downside is that it takes a signal almost half a second to travel the 22,000 miles from Earth. This might not sound like a lot, but it’s about 10 times the latency of someone using fiber-based internet. It’s fast enough to stream Netflix, but not fast enough to have fun gaming.

The alternative approach taken by SpaceX and OneWeb is a constellation, which packs hundreds or thousands of satellites into orbits just a few hundred miles above the Earth. To get total coverage, satellites are sprinkled between a few dozen rings around the Earth. Of the first 1,500 Starlink satellites, for instance, batches of 22 satellites each will occupy 72 different orbits at an altitude of 340 miles; OneWeb’s satellites will occupy 12 rings, with 49 satellites per ring at 745 miles up.

“The new space companies aren’t built on some incredible new technology,” says Iridium CEO Matt Desch. “They’re really just taking geostationary satellites with hundreds of beams and disaggregating that into hundreds of satellites in low earth orbit.”

That approach has its problems. First, the sheer number of satellites is staggering. SpaceX’s Starlink will have nearly 12,000 satellites, and OneWeb’s initial constellation will have 648; for the sake of comparison, there are only about 2,000 functioning satellites in orbit right now. With today’s Starlink launch, SpaceX will surpass the imaging company Planet as the operator of the world’s largest satellite fleet. It didn’t take astronomers long to realize that SpaceX’s satellites reflect a lot of light and could ruin the night sky for observations. (SpaceX says its working to fix the issue, and the latest batch of Starlink satellites will test an antireflective coating.)

Photograph: Paul Hennessy/Getty Images

Another issue is that an individual satellite can “see” a much smaller portion of Earth's surface compared to a geostationary satellite, which means the system relies on far more ground stations to connect the satellites to the global internet. Indeed, the next generation of Viasat satellites will need “hundreds” of ground stations to achieve global broadband coverage, but SpaceX recently submitted an FCC application for up to 1 million ground stations.

The upshot is reduced latency, because signals between a customer’s terminal and a satellite have to travel only a few hundred miles rather than several thousand. Coupled with improvements in download speeds—both OneWeb and SpaceX are expected to provide around 50 megabits per second, comparable to the average internet speed in the US—the promise is that you’ll finally be able to play Fortnite from space.

What remains to be seen is how SpaceX and OneWeb handle the terminals, which are the physical interface between a customer and the satellites in orbit. Both companies are planning to use phased array antennas in their terminals, which create steerable radio beams without requiring the antennas themselves to move. This allows a terminal to track satellites as they fly overhead and smoothly pass signals between them.

Neither SpaceX nor OneWeb would comment on their terminals, but these pizza-box-sized antennas will be critical to the success of their satellite internet businesses. According to Iridium’s Desch, it was the overpriced, bulky terminals that ultimately led to the downfall of Globalstar, a pioneer of telecom satellite constellations in the ’90s. A similar fate could await SpaceX or OneWeb if their terminals are too expensive or complicated for customers to set up.

“We still have a lot to do to get that right,” SpaceX president Gwynne Shotwell told reporters in October about the Starlink terminals. “The more engineering we do on the user terminal, the less service people we will have to hire. Knowing Elon, he wants everything to be beautiful, so the user terminal will be beautiful.”

But even if the companies manage to iron out all the technical and aesthetic hurdles, it’s still unclear whether the market is large enough to support these constellations. “They’re competing with the wired world, with Verizon, Comcast, and AT&T,” Desch says. This means they’re going to have to drastically reduce the price of satellite internet, which has historically been an expensive product. At the same time, a number of other companies, like Amazon and Telesat, are also working on broadband satellite constellations.

There’s never been more competition in the satellite internet game, which is good news for rural populations looking to get online. But unless someone figures out how to make it profitable, we might never get to ask for the Wi-Fi password on Mars.

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