Jan 8, 2020 08:30 AM
https://www.wired.com/story/how-spacexs-...ally-work/
EXCERPT: If you haven’t heard, there’s a new space race underway. The goal is to bring the “other 3 billion” people who lack internet access online using massive constellations of broadband satellites that number in the thousands. Leading the pack are SpaceX’s Starlink and OneWeb [...] The tension is understandable given the stakes. For OneWeb, the global adoption of space-based internet is critical to the company’s existence; for SpaceX, it is key to funding Elon Musk’s Mars ambitions.
[...] SpaceX says it will have enough birds in the air to start providing internet service by the summer. OneWeb says its constellation will offer limited service by the end of the year. Space-based internet is nothing new, of course. Companies like Viasat, HughesNet, and Iridium have been raining bits and bytes on Earth for decades.
No matter who you’re getting satellite internet from, the basics of the system are the same. A user sends packets of data from an antenna at their home toward a satellite, which relays these packets to a ground station back on Earth. [...] Once it reaches its destination ... a new packet of data is sent back to the ground station, beamed up to the satellite, and then beamed back to the user’s home.
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.
[...] 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. [...] 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 antireflective coating.)
[...] The upshot is reduced latency, because signals between a customer’s terminal and a satellite have to travel only a few hundred miles rather than several thousand. Coupled with improvements in download speeds—both OneWeb and SpaceX are expected to provide around 50 megabits per second, comparable to the average internet speed in the US—the promise is that you’ll finally be able to play Fortnite from space.
What remains to be seen is how SpaceX and OneWeb handle the terminals, which are the physical interface between a customer and the satellites in orbit... (MORE - details)
EXCERPT: If you haven’t heard, there’s a new space race underway. The goal is to bring the “other 3 billion” people who lack internet access online using massive constellations of broadband satellites that number in the thousands. Leading the pack are SpaceX’s Starlink and OneWeb [...] The tension is understandable given the stakes. For OneWeb, the global adoption of space-based internet is critical to the company’s existence; for SpaceX, it is key to funding Elon Musk’s Mars ambitions.
[...] SpaceX says it will have enough birds in the air to start providing internet service by the summer. OneWeb says its constellation will offer limited service by the end of the year. Space-based internet is nothing new, of course. Companies like Viasat, HughesNet, and Iridium have been raining bits and bytes on Earth for decades.
No matter who you’re getting satellite internet from, the basics of the system are the same. A user sends packets of data from an antenna at their home toward a satellite, which relays these packets to a ground station back on Earth. [...] Once it reaches its destination ... a new packet of data is sent back to the ground station, beamed up to the satellite, and then beamed back to the user’s home.
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.
[...] 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. [...] 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 antireflective coating.)
[...] The upshot is reduced latency, because signals between a customer’s terminal and a satellite have to travel only a few hundred miles rather than several thousand. Coupled with improvements in download speeds—both OneWeb and SpaceX are expected to provide around 50 megabits per second, comparable to the average internet speed in the US—the promise is that you’ll finally be able to play Fortnite from space.
What remains to be seen is how SpaceX and OneWeb handle the terminals, which are the physical interface between a customer and the satellites in orbit... (MORE - details)