MUSK: "It's growing rapidly."

Billionaire entrepreneur Elon Musk said on Tuesday that his satellite internet service Starlink - a project launched by SpaceX - was growing quickly, telling a crowd at the Mobile World Congress trade show in Barcelona that the number of Starlink customers could reach half a million over the next year.

MUSK: "We recently passed the strategically notable number of 69,420 active users. We're, I think, on our way to having a few hundred thousand users, possibly over 500,000 users within 12 months."

Starlink, an array of low-orbit satellites offering high-speed internet for people living in remote areas, is already offering a trial service and says it aims for near-global coverage of the populated world this year.

The Tesla CEO and founder of SpaceX also forecast total investment costs in his satellite internet business at as much as $30 billion.

MUSK: "Total investment is probably at least five, maybe $10 billion and then over time it's going to be, it's a multiple of that, and it could be $20 or $30 billion over time. It's a lot, basically."

Musk said Starlink has more than 1,500 satellites orbiting Earth and is operating in about a dozen countries and adding more every month.

Skeptics question whether satellite internet can ever develop a viable business model, because the main market it targets is people living in remote areas.

Musk also said he was talking to possible telecom partners as a number of countries require operators to provide rural coverage as conditions of their 5G licenses.