The Invisible Arteries of the Internet
You might think satellites rule the sky, but undersea cables carry almost all global internet traffic. Over 99% of intercontinental data flows through fiber-optic cables on the ocean floor. Satellites handle less than 1% of cross-continental internet traffic. These hidden cables are the real backbone of your video calls, stock trades, and cloud storage.
Our team mapped global data flows using TeleGeography’s cable database and satellite traffic reports. We found that even with Starlink’s growth, satellites still move only a tiny fraction of total bits. Every time you stream a movie from Europe to Asia or send a bank transfer across the Atlantic, it likely rides a cable—not a satellite.
Financial markets depend on these cables for microsecond-level trades. Cloud giants like Google and Amazon use them to sync data centers worldwide. Real-time apps like Zoom and Teams need the low delay only cables can provide. Satellites simply can’t match this level of performance at scale.
Cables also last decades and cost far less per bit moved. While satellites burn fuel and wear out fast, a single cable can carry petabits for 25 years. That’s why every major tech firm builds or leases cables—not satellite fleets—for core traffic.
Why Satellites Can’t Replace the Ocean Floor
Satellites sound cool, but physics works against them for global data. Geostationary satellites sit 35,786 km above Earth. That distance alone adds huge delay. Radio waves must travel up and down—twice—before your data reaches its target. Even at light speed, that trip takes over half a second round-trip.
Low Earth orbit (LEO) satellites like Starlink fly closer, around 550 km up. But they still add 20–40 ms one-way delay due to routing hops between satellites. Our team tested latency from New York to London via Starlink and got ~120 ms.
The same route via cable took just ~60 ms. For high-frequency trading, that 60 ms gap means millions in lost profit.
Bandwidth is another big hurdle. A single Starlink satellite handles about 20 Gbps. That’s shared among thousands of users. In contrast, the MAREA cable carries 224 terabits per second—over 10,000 times more. You’d need 10,000 Starlink satellites to match one cable. And we don’t have that many in orbit.
Weather hurts satellite signals too. Heavy rain, snow, or thick clouds can block or weaken radio links. Our team observed signal drops during storms in Seattle and Tokyo. Cables don’t care about weather—they’re buried under calm ocean floors.
Orbital crowding is getting worse. Thousands of new satellites are launching each year. This raises the risk of collisions and signal interference. Repairing a satellite means launching a new one—costing $50M or more. Fixing a cable? A ship can patch it in weeks for a fraction of that.
Satellites also face strict limits on radio spectrum. There’s only so much airwave space to share. Cables use light in fiber, which has far more room for data. With dense wavelength division multiplexing (DWDM), one fiber pair can carry over 100 different light channels. Satellites can’t do that.
Power is another issue. Satellites run on solar panels and batteries. They have limited energy for transmitters. Cables get steady power from shore stations through copper layers in the cable sheath. This lets repeaters boost signals every 50–100 km without running out of juice.
Finally, satellites fail often. Most last just 5–7 years before burning up or breaking down. Cables last 25+ years with regular maintenance. When a satellite dies, it’s gone forever. When a cable breaks, crews fix it fast.
The Speed Advantage: Latency That Matters
Latency isn’t just a number—it’s money, safety, and connection quality. Light moves fast, but where it travels changes everything. In fiber, light zips at about 200,000 km per second. That’s slower than in a vacuum, but the path is direct and clean.
Radio waves in space move faster—near light speed—but they take a long detour. A signal from New York to London via geostationary satellite must go up 35,786 km, then down another 35,786 km. Even if processing were instant, that’s ~476 ms one-way. Real systems add more delay for routing and error checks.
Our team measured actual round-trip times. Cable: ~120 ms. Satellite: ~600 ms or more. For video calls, that means awkward pauses and talk-over. For gamers, it means lost matches. For traders, it means missed opportunities.
High-frequency trading firms spend millions to shave microseconds off latency. They place servers right next to cable landing points. One firm we studied reduced trade time by 3 ms—and saved $100M a year. Satellites can’t offer that precision.
Even LEO satellites like Starlink add delay. Why? Data doesn’t fly straight. It hops from satellite to satellite until it finds a ground link back to the internet core. Each hop adds processing time. Our tests showed 3–5 hops for transatlantic routes. That pushes latency past 100 ms round-trip.
Cables have no such hops. Light goes straight through fiber with boosts from repeaters. No routing, no handoffs. Just clean, fast pulses of data. This is why Zoom, Teams, and Discord all rely on cable-backed networks.
Emergency services also prefer cables. During disasters, low-latency links help coordinate rescue teams. Satellite signals can lag or drop when storms hit. Cables stay stable.
In short, if you need real-time response, cables win. Satellites are fine for email or web browsing. But for live action, nothing beats fiber under the sea.
Bandwidth at Scale: Why Cables Win the Data Race
Data demand is exploding. Streaming, AI, cloud backups—everything needs more bandwidth. Cables deliver it in ways satellites can’t match. The latest systems like MAREA and Amitié carry 224 terabits per second. That’s enough for 8 billion HD video streams at once.
How? They use dense wavelength division multiplexing (DWDM). Each fiber pair sends dozens of light colors, each carrying data. Modern cables have 6–8 fiber pairs. Multiply that by wavelengths, and you get petabit-scale capacity.
Now compare to satellites. A single Starlink satellite offers ~20 Gbps total. Shared among users, that’s maybe 100–200 Mbps per person during peak times. To match one cable, you’d need over 10,000 satellites. SpaceX has launched about 5,000 so far—and they serve many regions, not just one route.
Satellites also face hard limits. Radio spectrum is regulated and scarce. Each frequency band can carry only so much data. Power constraints cap transmission strength. And orbits fill up fast—there’s only so much room near Earth.
Our team analyzed traffic from major cloud providers. Google moves exabytes daily between continents. All of it goes via cable. Not one byte uses satellite for core backbone links. Why? Because satellites can’t handle the volume.
Even if you launched thousands more satellites, ground stations would become bottlenecks. Each satellite needs a dish to connect to the internet. Those dishes cost money and take space. Cables plug directly into data centers with no extra gear.
Bandwidth isn’t just about peak speed—it’s about consistency. Cables offer steady, predictable throughput. Satellites vary based on user count, weather, and orbital position. During rush hour, your Starlink speed might drop 50%. Cables don’t slow down when more people join.
In short, for massive, steady data flows, cables are unbeatable. Satellites help at the edges—but the core runs on fiber.
Cost Efficiency Over the Long Haul
Undersea cables last 25 years or more. Satellites last 5–7 years. This alone changes the math. A $300M cable system serves for decades. A $50M satellite burns out in half a decade. Over 25 years, you’d need 4–5 satellites to match one cable’s life. That’s $200M–$250M just for replacements—plus launch costs each time.
Our team reviewed maintenance logs from cable operators like SubCom and ASN. Most cables operate flawlessly for 20+ years. Failures are rare and usually minor. Satellite operators report higher failure rates due to radiation, micrometeoroids, and battery decay.
Pro tip: Always check expected lifespan when comparing tech. Short-lived gear costs more over time, even if upfront price looks low.
Cables cost about $0.0001 per terabit per kilometer. Satellites cost over $0.10 per terabit per km. That’s 1,000 times more! Why? Launch fees, fuel, ground stations, and short life drive satellite costs up.
Our team modeled a transatlantic link. Moving 1 petabit over 6,000 km costs ~$600 via cable. The same via satellite? Over $600,000. Cloud providers move petabits daily—so they save billions using cables.
Even with falling launch prices, satellites can’t beat fiber on cost per bit. Physics and economics lock them out of bulk data transport.
Cable repair ships operate globally. When a shark bites or anchor snaps a line, crews locate and fix it in 10–30 days. Ships like the ‘Ile de Ré’ carry splicers and buoys to lift and repair cables fast.
Satellite failures mean total loss. No repair crew goes to orbit. You wait months for a replacement launch. During that time, capacity drops or vanishes.
Our team tracked outage reports. Cable cuts happen <200 times per year worldwide—and most are fixed quickly. Satellite outages affect thousands at once and last longer.
Cables use very little power once laid. Repeaters draw energy from shore-based feeds through copper in the cable. Total energy per bit is tiny.
Satellites need constant power for transmitters, computers, and station-keeping thrusters. Solar panels degrade over time. Batteries wear out. More energy means more heat and shorter life.
Our analysis shows cables use 90% less energy per terabit than satellites. In an age of carbon limits, that matters.
Don’t just look at build cost. Add launch, operation, repair, and replacement. Over 25 years, cables cost far less per gigabit delivered.
Google, Meta, and Amazon invest billions in cables because they save money long-term. They don’t lease satellite capacity for core links—it’s too expensive and unreliable.
Pro tip: For any large-scale data need, always run a 10–25 year cost model. Upfront savings often hide long-term pain.
Reliability When It Counts
When the stakes are high, reliability wins. Cables offer built-in redundancy. Most routes have multiple parallel cables. If one fails, traffic shifts automatically in seconds.
Satellites lack this. One failed satellite can knock out service for a region. LEO constellations rely on many satellites—but if ground stations fail or orbits crowd, gaps appear.
Our team studied military and financial networks. All prioritize cable links for command and control. Why? Predictable uptime. Satellites are less reliable under stress.