SpaceX, the Elon Musk-backed rocket manufacturer, ambitiously plans to put 4,425 satellites into space.

The detail was included in a Federal Communications Commission filing earlier this week.

Musk first announced the project back in January 2015 when he pegged its cost at $10 billion. The current filing did not update. The full name of the company is Space Exploration Technologies and its other backers include Alphabet and Fidelity Investments.

The plan is to initally launch 800 satellites to widen internet coverage in the US, including Puerto Rico and the US Virgin Islands. The balance of the satellites will follow, improving coverage globally. However, no timeline is laid out for the venture.

“The system is designed to provide a wide range of broadband and communications services for residential, commercial, institutional, government and professional users worldwide,” said the FCC filing.

SpaceX’s satellites will orbit at altitudes between 1,150 kilometers and 1,275 kilometers, classifying them as low-earth orbit (Leo) satellites. The idea is to provide a dense network coverage with each satellite covering around 2,120 kilometres on the ground. Once running at full capacity, the system would provide bandwidth of 1 Gb/s.

Back in the nineties, a number of ventures, including Motorola-backed Iridium tried (unsuccessfully) to build Leo-based satellite systems to offer global communications coverage

SpaceX is not alone in its ambitions. Other internet-via-satellite ventures are under development by Oneweb, whose backers include Richard Branson, and Boeing.