The two largest satellite internet providers in the US, HughesNet and Viasat, both use satellites the size of a car to deliver their service. They sit in geostationary orbit, which means they always stay in the same position relative to the surface of the Earth and have hundreds of gigabits per second of network capacity. The advantage of this approach is that a single satellite can provide internet services for an entire continent. The downside is that it takes a signal almost half a second to travel the 22,000 miles from Earth. This might not sound like a lot, but it’s about 10 times the latency of someone using fiber-based internet. It’s fast enough to stream Netflix, but not fast enough to have fun gaming.
The alternative approach taken by SpaceX and OneWeb is a constellation, which packs hundreds or thousands of satellites into orbits just a few hundred miles above the Earth. To get total coverage, satellites are sprinkled between a few dozen rings around the Earth. Of the first 1,500 Starlink satellites, for instance, batches of 22 satellites each will occupy 72 different orbits at an altitude of 340 miles; OneWeb’s satellites will occupy 12 rings with 49 satellites per ring at 745 miles up.
“The new space companies aren’t built on some incredible new technology,” says Iridium CEO Matt Desch. “They’re really just taking geostationary satellites with hundreds of beams and disaggregating that into hundreds of satellites in low Earth orbit.”
That approach has its problems. First, the sheer number of satellites is staggering. SpaceX’s Starlink will have nearly 12,000 satellites and OneWeb’s initial constellation will have 648; for the sake of comparison, there are only about 2,000 functioning satellites in orbit right now. With today’s Starlink launch, SpaceX will surpass the imaging company Planet as the operator of the world’s largest satellite fleet. It didn’t take astronomers long to realize that SpaceX’s satellites reflect a lot of light and could ruin the night sky for observations. (SpaceX says its working to fix the issue, and the latest batch of Starlink satellites will test an anti-reflective coating.)
Another issue is that an individual satellite can “see” a much smaller portion of the Earth compared to a geostationary satellite, which means the system relies on far more ground stations to connect the satellites to the global internet. Indeed, the next generation of Viasat satellites will need “hundreds” of ground stations to achieve global broadband coverage, but SpaceX recently submitted an FCC application for up to 1 million ground stations.
social experiment by Livio Acerbo #greengroundit #wired https://www.wired.com/story/how-spacexs-satellite-internet-will-actually-work