Positioning, Navigation, and Timing (PNT) Satellites
The European Union (EU) is developing a PNT system called Galileo. The Galileo constellation will consist of ## operational satellites and three in-orbit spares. In October 2011, the first ## Galileo in-orbit validation (IOV) satellites were launched, and ## more IOV spacecraft were scheduled to launch by mid-2012. The initial Galileo constellation is expected to be in place between 2014 and 2016. However, financing may be a concern. The EU has already approved contracts for ## additional satellites with OHB of Germany, but the number of additional satellites that can be ordered depends in part on the European Commission’s calculation of exactly how much money remains in the seven-year budget, with the next budget commencing in 2014.
Since 2000, China has also been building its own national PNT system, known as Beidou (the Mandarin name for the constellation otherwise known as the Big Dipper). China launched ## satellites in 2011 to join the ## currently in orbit. These satellites will later become part of a global constellation, Compass, which is planned to consist of ## MEO satellites for global coverage and ## GEO satellites that will focus on regional coverage over China. Beidou began operating in December 2011, providing initial PNT services to a swath of the Asia-Pacific region from Australia in the south to Russia in the north with an accuracy of 25 meters (82 feet).
A launch in October 2011 raised the number of operational satellites in Russia’s GLONASS system to ##, enabling full global coverage for the first time since the 1990s. GLONASS was designed to serve both military and civilian populations. The original Soviet system began deployment with the 1982 launch of its first satellite. However, due in part to Russia’s economic difficulties in the 1990s, the network fell into disrepair. In 2001, President Vladimir Putin ordered a 10-year, $## billion modernization program.
Although many generically use the term “GPS” to refer to the overall concept of satellite-based navigation, this acronym only refers to one specific network. The U.S. Navigation Signal Timing and Ranging Global Positioning System (NAVSTAR-GPS or GPS) was developed and deployed by the U.S. Air Force and was the first fully operational global satellite-based navigation network. The GPS constellation nominally requires ## operating satellites but in practice maintains more satellites in orbit.
Note: This exhibit is from The Space Report 2011.
Note: This exhibit is from The Space Report 2010.
The complete constellation is planned to be in place by 2011, though no launches had been conducted by the end of 2009. Japan’s Quasi-Zenith Satellite System (QZSS) will consist of ## GEO satellites operating over Japan and surrounding areas. While these satellites are geosynchronous, orbiting the Earth once per day, they are not stationary as are FSS satellites. They are inclined-GEO satellites, meaning that they move in a north-south “figure eight” pattern as observed from a single point on the Earth.
China is planning to supplement its Compass Satellite network already in development. In April 2007, China launched BeiDou-2, the first MEO satellite for Compass. Plans have been announced for the launch of ## PNT satellites over the next two years. This network, limited to the Asia Pacific region initially, may be operational by the end of 2010.