From New Scientist: https://www.newscientist.com/articl...-at-how-elon-musks-space-internet-could-work/ The first detailed look at how Elon Musk’s space internet could work By Douglas Heaven IT IS no secret that Elon Musk wants to build a space internet. His company, SpaceX, has been granted permission by the US Federal Communications Commission (FCC) to set up a vast network of thousands of low Earth orbit communication satellites. But the company has been tight-lipped about the project, known as Starlink. Now Mark Handley at University College London has created a detailed simulation of what Starlink might look like, which he will present at a conference next week. Although Musk has said he wants more than half of all internet traffic to go through Starlink – Handley’s simulation suggests that the project will be most appealing to high-frequency traders at big banks, who might be willing to fork out large sums for dedicated, faster connections. To create the simulation, Handley took what information he could from SpaceX’s public FCC filings and combined this with his knowledge of computer networks. Initially, Starlink will consist of 4425 satellites orbiting between 1100 and 1300 kilometres up, a greater number of active satellites than are currently in orbit. There is only one way to arrange this many in a configuration that minimises collisions, says Handley. So he is confident that his simulation reflects what SpaceX is going for. When sending an internet message via Starlink, a ground station will begin by using radio waves to talk to a satellite above it. Once in space, the message will be fired from satellite to satellite using lasers until it is above its destination. From there, it will be beamed down to the right ground station using radio waves again. Between distant places, this will allow messages to be sent about twice as fast as through the optical fibres on Earth that currently connect the internet, despite having to travel to space and back. This is because the speed of the signal in glass is slower than it is through space. For most people, the regular internet is fast enough already. But for certain applications – such as high-frequency trading, where fortunes can be made and lost in a millisecond – a speed-up as big as this could be worth many billions. The simulation also reveals that there will be more satellites, and thus better coverage, at latitudes between 47 and 52 degrees north and south, roughly over London, Paris and Frankfurt, and not far from New York, which are all international trading centres. Paying customers will be crucial, because the costs of launch and maintenance will be eye-watering. Launching a single satellite costs tens of millions of dollars. Each Starlink satellite will probably only last a few years, so SpaceX will need to launch new satellites to replace dead ones every few weeks. “To maintain just 4425, you’re going to be launching that number every five years,” says Hugh Lewis at the University of Southampton, who represents the UK Space Agency on the Inter-Agency Space Debris Coordination Committee. The global coverage will mean Starlink could bring internet to otherwise inaccessible places, from ships at sea to mountain villages (see “box”). All you would need is a solar-powered suitcase-sized box to talk to the nearest satellite. SpaceX launched two test satellites in March and is aiming to start sending up the first proper Starlink satellites in 2019. The company declined New Scientist‘s request for comment. Starlink is a vast undertaking in its own right, but Handley is convinced it is all for the sake of a bigger one. “Musk’s raising money for the Mars programme,” he says.