Billionaire entrepreneur Elon Musk's SpaceX has raised more than $1 billion in financing in the last six months as it aims to roll out an ambitious high-speed internet service by using a constellation of satellites to beam signals from space.

The company raised $486.2 million in an equity offering, starting December, and another $535.7m in an offering that began in April, its regulatory filings on Friday showed.

The rocket company on Thursday launched the first batch of 60 small satellites into low-Earth orbit for Musk's new Starlink internet service.

Musk sees the Starlink venture as an important new revenue stream for his California-based company, whose launch service income he expects to top out at around $3bn a year.

At least 12 launches carrying similar payloads are needed to achieve constant internet coverage of most of the world, Musk said. For now, Starlink is only authorised for United States operations.