SpaceX has asked the U.S. government for permission to launch an internet network powered by thousands of satellites above the Earth.

According to documents filed with the FCC, SpaceX plans to deploy more than 4,000 satellites to create a global, high-speed internet network. The initiative was first floated by CEO Elon Musk in early 2015, around the time that Google participated in a $1 billion investment in the company. Musk then estimated the project would take at least five years and cost around $10 billion. Google was thought to have been attracted to the Tesla deal for the potential to make internet connectivity more accessible on a global scale, that’s something that a satellite-powered network would certainly play a part in enabling.

At this point, however, it isn’t clear exactly what the purpose of the network may be. Might it be utilized by other ventures from Musk? Tesla could use a global network to provide connectivity to its vehicles worldwide, for example. Could it be resold to other providers? Time will tell.

It could also be a blueprint for more ambitious plans — this is Elon Musk we are talking about here, after all. The SpaceX CEO last year hinted that the project could lay the foundation for an internet service in Mars, the planet he famously looking to colonize. Internet access would be a basic requirement for anyone who wanted to travel to the Red Planet, particularly given the high cost of such a trip, and Musk reckons the first flight could happen within the next decade.

One thing that we can be more sure of is that SpaceX is looking to start the project gradually. GeekWire reported that it will begin with an initial fleet of 800 satellites, assuming that it is successful with its application, which would then be increased over time.

It isn’t the only company looking at this kind of internet access. OneWeb, a venture backed by the likes of Airbus and Virgin, and Boeing are both exploring the potential. OneWeb said this summer that it is on track to have its satellites in orbit before 2020, but at this point it has only completed the preliminary design review. Samsung also expressed interest, but has not taken its proposal further than a white paper.