One of SpaceX’s most ambitious projects remains tethered to the ground — for now

FAN Editor

A stack of 60 SpaceX Starlink satellites float in orbit above the Earth.

Source: SpaceX

To fund its Martian ambitions, SpaceX intends to transform the Earth — blanketing the planet in ubiquitous internet coverage beamed down from a tight-fitting mesh of thousands of satellites. CEO Elon Musk expects this “Starlink” service to eventually generate $30 billion per year.

In space, construction is advancing smoothly. SpaceX has already become the world’s largest satellite operator, managing more than 500 satellites and counting. That’s a fraction of the thousands it intends to launch, but enough for the system to reach Air Force cockpits and connect Musk to Twitter. The company intends to start beta testing in North America this summer.

On the ground, however, SpaceX still has work to do. It has yet to unveil hardware to connect a customer’s home to the satellites flying overhead. The company will also need a network of ground stations linking its satellites to the internet’s physical backbone. Building these nodes is hardly rocket science: indeed 26 are already planned for the U.S. But without a crucial satellite upgrade, those stations will keep the network’s coverage stuck largely to the land.

“It’s very much not initially a global service,” says Tim Farrar, the president of TMF Associates, a satellite and telecom research firm, “even though the satellites are flying all over the place.”

Beaming back global broadband

Efforts to beam data down from the skies have typically fallen into two categories: the very near and the very far. Google parent company Alphabet is deploying internet balloons about 12 miles above the ground in Kenya, for instance, and Facebook has its eye on solar-powered drones. These near-surface approaches are speedy, but each floating antenna has a limited geographic footprint.

In contrast, companies like the Canadian communications firm Telesat have long operated handfuls of satellites in high orbits more than 20,000 miles above Earth’s surface, where each machine can reach a wide swath of the planet. These systems offer global coverage, but snail-like connections, with round trip signals taking more than half a second. “That doesn’t sound like a big deal, but a typical web page might have 100 round trips,” says Telesat vice president Erwin Hudson. “It adds up.”

With Starlink, SpaceX joins a fray of companies, including Telesat, all racing to deliver the best of both worlds: “constellations” of satellites close enough to communicate with the ground in tens of milliseconds, but far enough to cover the planet with a reasonable number of satellites. To complete the service, however, SpaceX needs two more pieces of ground-based infrastructure.

Starlink’s biggest land-based hurdle

Starlink’s major terrestrial hurdle, Musk acknowledges, is the antenna that will get users online — the internet analog of the TV parabolic dish. Starlink’s low-flying satellites zoom across the sky in about five minutes, and antennas will need to keep up. SpaceX’s design has to balance technological sophistication with mass-market affordability.

The company plans to use “phased array antennas,” which can direct the machine’s focus electronically rather than physically spinning it around. The technique simplifies the device mechanically, but comes at a high price. Farrar estimates that the gadget could cost more than $1,000, although Musk is targeting a price tag of under $300. In March, the FCC authorized SpaceX to distribute one million antennas, and SpaceX board members recently tested the devices (which reportedly resemble “UFOs on a stick”), but the company has not yet announced the retail version. 

Any satellite service also needs a network of ground stations to tap into existing fiber optic infrastructure. These are the points where the space network fuses with the world wide web. “What goes up must come down,” Hudson said.

SpaceX is preparing these “gateway” stations, too. The company has registered 26 locations with the FCC, each of which can host eight antennas. Some are SpaceX-owned properties while others belong to telecommunications companies, such as Level Three Communications, which can presumably supply high-speed hookups. Handfuls of mushroom-shaped domes — radar transparent weather protection for antennas — have recently cropped up on some of the lots.

Why ‘crosslinking’ is the key concept

These gateways are just the beginning. For maximum performance, Starlink will eventually need thousands of gateway antennas (roughly one per satellite) spread across hundreds of sites worldwide, according to Íñigo del Portillo Barrios, a recent MIT graduate who has analyzed the structure of the Starlink and Telesat constellations.

He says Starlink relies heavily on these stations because the current batch of satellites lacks an originally planned feature for the machines to communicate with their neighbors via lasers. This “crosslinking” ability would let Starlink pass a signal to any user below any satellite — even those in the air, on remote islands, or in conflict zones. But without it, a satellite must be able to link a user with a gateway antenna directly, limiting coverage to within roughly 500 miles of each ground station, Farrar estimates.

“They’ll have big holes in the middle of the oceans and some deserts,” Farrar said. “They’ll need to go to a country’s regulator and say, ‘please let us in, please let us build the gateways in your country.'”

That’s hardly a showstopper for reaching most rural areas (currently planned stations will cover most of the U.S. and Mexico). But traditional satellite internet clients such as the military, who might desire access over central Iraq for example, or airlines and shipping companies seeking connectivity in the Atlantic and Pacific, may prefer to wait for a truly global service.

SpaceX did not respond to a request for comment on its gateway or crosslinking plans, but Hudson says that even though Telesat has 50 years of satellite experience and plans to start launching crosslink-enabled satellites in 2022, choreographing ground operations will still represent one of their major challenges.

“We’re building earth stations on every continent except possibly Antarctica,” he said. “You’ve got to ship stuff everywhere. You’ve got to get it built, maintained, and upgraded.”

Adding crosslinking will eventually help SpaceX lessen the sway geography has on Starlink’s coverage, and the company intends to start experimenting with interlinked satellites sometime this year, president Gwynne Shotwell has said.

But the upgrade won’t be simple, and the second-generation network won’t be operational in the immediate future. First SpaceX needs to overhaul its satellite design to incorporate a beefier power supply, finely tuned lasers, and other hardware. Then it will also have to rebuild and relaunch the entire swarm.

The company can pull it off eventually, Farrar said, but first Starlink will have to prove its worth with the satellites it has in the sky, and the gateway stations it can build on the ground.

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