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Precision Navigation In European Skies

Geostationary satellites provide differential GPS with a positioning accuracy of 1-2 meters

3 min read

A global system of air traffic control based entirely on global positioning systems, an inevitable idea that has been inching toward realization for more than a decade, came a centimeter or two closer on 6 June, with the first transmission of test signals from the European Geostationary Navigation Overlay Service (Egnos). The point of Egnos is to provide error correction to geopositioning signals, relying on dedicated equipment installed on three geostationary satellites and a network of ground reference stations [see map], so that locations can be determined at an accuracy of close to 1 meter.

For now, Egnos will error-correct signals from the U.S. Global Positioning System (GPS) and Russia’s Global Navigation Satellite System (Glonass). Eventually, though, the expectation is that it will error-correct signals from Europe's own constellation of global positioning satellites, dubbed Galileo. Galileo will rely on 30 low-earth-orbiting satellites, together with ground stations, and is expected to begin transmitting its first test signals in 2006.

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Two men fix metal rods to a gold-foiled satellite component in a warehouse/clean room environment

Technicians at Northrop Grumman Aerospace Systems facilities in Redondo Beach, Calif., work on a mockup of the JWST spacecraft bus—home of the observatory’s power, flight, data, and communications systems.

NASA

For a deep dive into the engineering behind the James Webb Space Telescope, see our collection of posts here.

When the James Webb Space Telescope (JWST) reveals its first images on 12 July, they will be the by-product of carefully crafted mirrors and scientific instruments. But all of its data-collecting prowess would be moot without the spacecraft’s communications subsystem.

The Webb’s comms aren’t flashy. Rather, the data and communication systems are designed to be incredibly, unquestionably dependable and reliable. And while some aspects of them are relatively new—it’s the first mission to use Ka-band frequencies for such high data rates so far from Earth, for example—above all else, JWST’s comms provide the foundation upon which JWST’s scientific endeavors sit.

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