ARS Technica Eric Berger - 8/25/2022
"So it's really quite a difficult technical challenge."Delivering space-to-ground internet to mobile phones will require SpaceX to finalize development of its second generation of Starlink satellites. These will be significantly larger than the current ones, which have a mass of about 295 kg. SpaceX founder and chief engineer Elon Musk said project could enter "beta service" before the end of 2023.
How this would workThe solution to this problem is using a much more powerful phased array antenna on the second version, or V2, of the Starlink satellites. Musk said the body of these satellites would be about 7 meters long, and the antenna would fold out to be about 5 meters on a side, or "roughly 25 square meters." As the satellite passes overhead, this antenna will send and receive data along a focused beam passing across the planet's surface.
Initially, at least, the service would not provide broadband internet service. But in a typical cell of service, it should provide up to 2 to 4 megabits of data, enough for thousands of voice calls or millions of text messages. This would allow connectivity in areas off the grid, or during emergency situations such as when a hurricane knocks out service to a community.
The challengesBeyond regulatory issues, SpaceX faces several major challenges to make this all work. Principal among them is designing and building the large satellites capable of talking to mobile phones.
"These are the most advanced antennas in the world, we think," Musk said. "They have to pick up a very quiet signal from your cell phone. Just imagine, that signal has to travel 500 miles, and then be caught by a satellite that's traveling at 17,000 mph. The satellite's got to compensate for the Doppler effect of moving so fast."
Then they have to get the satellites into space. The V2 satellites are too large for company's Falcon 9 rocket's payload fairing, which is 5 meters across. So the full-size Starlink V2 satellites will need to wait for the much larger Starship rocket to come online. SpaceX is working toward doing just that at the Starbase facility in South Texas, but operational launches are likely at least a year away.
The competitionSpaceX has already launched satellites for one competitor in this area, Lynk, and is due to launch the "BlueWalker 3" demonstration satellite for another company AST Space Mobile, later this year. Both of these companies are attempting to deliver direct-to-cellphone service.
Lynk says it has already successfully demonstrated the ability to use ordinary, unmodified mobile telephones to connect to satellite Internet services. The company presently has one operational satellite in space, but is planning to launch more, to provide a wider area of coverage.
“Elon said it's hard, and it’s only been done in the lab, but Lynk has done it in space already," Miller said in an interview Thursday night. "We’re the only company in the world that has done that."
More:
https://arstechnica.com/science/2022/08/forget-5g-wireless-spacex-and-t-mobile-want-to-offer-zero-g-coverage/
