New Global Navigation Satellite Systems Rising
October 19, 2011 Leave a comment
The first two operational satellites in a new European Union global navigation satellite system are set to launch this Thursday. They’ll form part of a 27-satellite system called Galileo as a European alternative to GPS, which is run by the U.S. Little did I know that Russia also has its own system called GLONASS, which this month achieved worldwide coverage, and that China has launched 9 out of the 35 satellites that will comprise its own system, called Compass.
I’m guessing that when these are all in full use, they’ll be able to be coordinated for unprecedented accuracy, even though the signals made available to civilians are less accurate than those for the military. It could also bring new space tension to international relations; I could only imagine what it was like as an EU representative explaining to your American allies that you wanted your own independent satellite system, just in case.
This was brought to my attention by an article at GPS Daily with facts on the Galileo system. Here are just a few points from the article:
Galileo will consist of 30 satellites, six more than the US Global Positioning System (GPS). The system will offer several services from 2014, becoming fully operational in 2020 when a constellation of 27 satellites, supported by three spares, is deployed…
HOW IT WORKS: Like GPS, Galileo works by the geometrical process called triangulation. The satellites emit synchronised signals in the 1.1-Gigahertz (GHz) band. Ground receivers capture the signals and compute the time it takes for each signal to arrive from their brief journey across space. Minute differences in time, caused by the varying distances, enable a calculation of the receiver’s position on the Earth’s surface.
ATOMIC TIME-KEEPING: Galileo depends on atomic clocks to ensure that location data is precise. One billionth of a second too fast or too slow translates into an positioning error of about 30 centimetres (12 inches).
The satellites will each contain four timepieces accurate to one second in three million years.
In two hydrogen clocks, hydrogen atoms oscillate between two energy states to generate a signal in the form of an electromagnetic wave. Two compact rubidium clocks use the transition of the rubidium-87 atom between two hyperfine energy states.
ROLLOUT: Two test satellites were launched in 2005 and 2008. The first two operational satellites are scheduled to be hoisted on October 20 by Soyuz, making the Russian rocket’s maiden launch from Europe’s spacebase.
Two more will follow in 2012, forming the constellation’s operational nucleus. Fourteen satellites should be in place by 2015 and able to offer three services, and the rest by 2020. The network will be managed by two control centres in Europe and sensor and uplink stations around the world. The system is designed to be compatible with GPS and Russia’s GLONASS.
This is a pretty interesting time. I don’t know what new advances are going to result from these new navigation systems, but I’m sure it’ll be cool and unexpected.
Edit: It looks like the future is now: the new iPhone 4S is using GLONASS along with GPS for positioning information.