Satellites may connect the entire world to the internet

#News(General) [ via IoTForIndiaGroup ]

OneWeb is among several firms that are trying leo satellites again. SpaceX, a rocket company founded by Elon Musk, a tech entrepreneur, is guarded about its proposed system, Starlink, but on November 15th American regulators approved an application for 7,518 satellites at an altitude of 340km (bringing the total for which the firm has approval to nearly 12,000). Telesat, a Canadian firm, has plans for a 512-satellite constellation. LeoSat, a startup with Japanese and Latin American backers, aims to build a 108-satellite network aimed at providing super-fast connections to businesses. Iridium, still in the game, will launch the final ten satellites in its new constellation of 66 by the end of the year. Not to be outdone, a Chinese state-owned firm recently announced the construction of a 300-satellite constellation. In ten years’ time, if all goes to plan, these new firms will have put more satellites into orbit by themselves than the total launched to date .

These companies want to avoid the technical issues of geostationary satellites by putting theirs into a low orbit, where the data will take only a few milliseconds to travel to space and back. And because signals need not be sent so far the satellites can be smaller and cheaper. OneWeb claims they might weigh 150kg and cost a few hundred thousand dollars, compared with a tonne or more, and tens or even hundreds of millions of dollars, for the geostationary sort.

One way to understand this is as a cellular-phone network turned inside out. On Earth, cell-phone towers are fixed; a user’s phone talks to the closest or least busy one, which may change as the user moves or traffic alters. In OneWeb’s system each satellite is a moving cell tower, circling the Earth from pole to pole in one of 18 orbital planes that look like lines of longitude (see diagram). The 900 cells, each one covering an area of a bit more than 1m kilometres, skim across the Earth at 26,000km an hour. Clever software hands transmission from one satellite to the next as they move into and out of range.

Aerial combat
Firms such as Kymeta, along with at least two other companies, Phasor and Isotropic Systems, are producing flat, electronically “steerable” antennae with no moving parts that can send and receive signals from leo satellites

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