How many satellites make up the Galileo system?
Galileo is the Global Navigation Satellite System (GNSS) in Europe, and will consist of 30 satellites (27 operational and 3 reserve) distributed in three orbital planes MEO 23,222 km altitude above the Earth with an inclination of 56 degrees with respect to Ecuador. The satellites to be distributed evenly in each plane and will take 14 hours to complete one orbit to Earth. Each plane will have nine operational satellites and one reserve. Why Europe needs Galileo? Satellite positioning has become the standard form of navigation. If the satellite signals were stopped suddenly, many ships and planes would have difficulty re-use traditional navigation techniques. The European Commission (EC) estimates that 6-7% of EU GDP - around 800 billion euros in monetary terms - depends on satellite navigation services. However, European consumers have no alternative but to determine their position with the system GPS U.S. or the Russian GLONASS system.
How accurate is? With 30 satellites at this altitude, the probability is very high (greater than 90%) to see at least four satellites at any time from anywhere in the world, which is in principle sufficient to determine accurately the position of the user. Normally we would be always in sight of six to eight satellites , which can calculate the position with a margin of error will be the order of a few centimeters. With support for GPS, Galileo will double the number of visible satellites at any time. What improvement compared to the Galileo GPS? On the one hand, to calculate the position with great precision virtually anywhere in the world, even in big cities where buildings obscure the signal from the satellites near the horizon.
Furthermore, improving the reception of navigation signals at high latitudes. Galileo satellites will be placed in orbits with higher inclination than the GPS, which will improve the reception quality at high latitudes and the poles, particularly in northern Europe. When available navigation services? The second phase begins with the launch of the first four operational satellites, two on October 20, 2011 and two in mid-2012. Between 2012 and 2014 will be launched 14 satellites, which will supply the first navigation service in 2015.