SpaceX the Alan Notes

When a balloon looks like a satellite

There are surprising similarities between Project Loon and Musk’s proposed SpaceX network as well as OneWeb. The two projects not only appear to share the goals – to connect the farthest corners of the Earth with low-cost internet – but the basic architectures of the networks would be the same.

Google is building a vast network of balloons that surf the stratospheric winds 12 miles up in loosely defined latitudinal orbits around the world. Those balloons use a radio broadband link to connect to transmitters on the ground and mesh networking techniques to link to the other balloons on the horizon, creating a kind of floating internet in the sky. Data is passed from balloon to balloon until it’s within site of a ground receiver, which offloads that data into the internet proper.

Musk’s plan calls for essentially the same scheme, just 740 miles higher up. The original talk of 700 orbiters has now turned into plans for a a constellation with as many as 4, 00o satellites. In low-earth orbit, those satellites would be skimming the top of the Earth’s atmosphere, 30 times closer to the surface (and your PC or smartphone) than the geostationary satellites that today carry the bulk of our orbital internet traffic. They won’t be floating like Loon Balloons, but those satellites are still bound by the laws of physics. At that altitude, they’ll need to travel at 16, 000 mph and would complete a full orbit of the Earth in a little less than two hours – otherwise they’d fall out of the sky.

That means from a vantage point on Earth these birds will be whizzing overhead. So as with Loon, an Earth-based transmitter won’t be connecting to a single Musk-built orbiter, but multiple. Both balloon and satellite would pass your connection on to the next balloon or satellite as they pass overhead. Data would then flow from balloon to balloon and from satellite to satellite until they found their appropriate ground-based links.

A new spin on the orbital constellation

As those Iridium flares readily demonstrate, there’s already plenty of hardware in the heavens dedicated to providing global internet access. What will Musk or OneWeb’s constellations do that Iridium or Globstar’s won’t? Or for that matter what Project Loon or other sky-bound internet projects like Facebook’s drones?

While Iridium and Globalstar may have pioneered the globe-spanning internet constellation, they also have limited number of satellites in the sky (66 for Iridium, 32 for Globalstar). Putting more birds in orbit is the equivalent of adding more towers to an urban cellular network: fewer people are connecting to the same cells so every user can tap faster speeds and there’s more overall capacity throughout the entire system.

Iridium and Globalstar are also focused on providing mobile internet connectivity from satellite phones and modems to a network far above. That’s very useful for leaving a GPS breadcrumb trail for a lost airplane or maintaining contact with dog sleds racing in the Iditarod, but Musk appears to have more stationary transmitters in mind. A high-power antenna aimed at a satellite can produce a lot higher data speeds than one you carry in your backpack.