Microsoft and Facebook to lay Atlantic cable

Microsoft and Facebook have announced plans to lay a trans-Atlantic communications cable from Virginia to Spain.

Running from Virginia Beach, Virgina to Bilbao, Spain, MAREA (which is Spanish for “tide”), it will be the first cable to connect the US to southern Europe, over a distance of 6,600 km (4,100 miles). From Blibao, it will connect to network hubs in Europe, Africa, the Middle East and Asia, with the goal of improving speed and reliability. For Microsoft this means improvements for users of its cloud services, such as Bing, Office 365, Skype, Xbox Live, and Microsoft Azure, while for Facebook it means improvements for users of its eponymous social network.

I find this story very puzzling. The whole reason communication satellites exist is because they have historically been far cheaper to build and launch with far greater capacity than ocean cables. Thus, the decision of these companies to go with an undersea cable instead of satellites suggests that something has changed in that equation, though I can’t see what. Have undersea cables improved so much that they have a bigger capacity than satellites, so much bigger that it compensates for the higher cost of installation and maintenance?