Positioning, Navigation, and Timing (PNT) Satellites
Japan’s Quasi-Zenith Satellite System will supplement GPS coverage over areas of Japan that prove difficult with GPS alone. The first launch is expected in 2010.
The Indian Regional Navigational Satellite System is under development by the Indian Space Research Organisation (ISRO). The introduction of these competing systems, with newer spacecraft and stronger signals, should improve global coverage, accuracy, and reliability.
The European Union continues to develop the ##-satellite Galileo constellation, expected to be launched in 2010. Funding has been approved for the project, and in April 2008 the second GIOVE (Galileo In-Orbit Validation Element) test satellite was launched.
The Global Navigation Satellite System, or GLONASS, is the Russian equivalent of the U.S. GPS and is designed for both military and civilian use. The network became operational in 1995, but declined during Russia’s economic downturn and is in the process of being reconstituted. In 2008, the system added ## additional satellites to expand the constellation to ##. However, GLONASS signals are encoded in such a way that equipment manufacturers cannot easily incorporate them into user terminals compatible with GPS or some of the newer global navigation satellite systems coming on line.
The U.S. Navigation Signal Timing and Ranging Global Positioning System (NAVSTAR GPS or GPS) is the only fully operational satellite-based navigation network. Best known from its widespread commercial applications, the network was deployed and is operated by the U.S. Air Force. The GPS fleet consists of ## satellites in MEO, and has been in full operation since 1995.
Note: This exhibit is from The Space Report 2009. Please refer to this year’s exhibits for the most current data as numbers may have been revised since this edition was published.
In 2006, India announced the Indian Regional Navigation System (IRNSS), joining the ranks of countries with plans for indigenous navigation systems. IRNSS is to be a ##-satellite geostationary and geosynchronous system developed over the next six to seven years.
The first launch of Japan’s Quasi-Zenith Satellite System (QZSS) is scheduled for 2009. QZSS uses ## geosynchronous satellites in orbital planes designed to have observed elevations of 60 to 70 degrees over Japan. These observed elevations will avoid interference from urban canyons or mountains.
Galileo, Europe’s proposed ##-satellite navigation constellation, reached a key funding agreement in 2007 when the European Council agreed to fund the project entirely though the European Union community budget. The hoped-for significant private-sector participation did not materialize. With these issues resolved the constellation could be operational as early as 2013.
Russia has recently committed to upgrading its Global Navigation Satellite System (GLONASS) to full operational capacity of ## operational satellites by late 2009. The GLONASS system, once set to rival the U.S. GPS system, saw its number of operational satellites fall from ## in 1995 to seven in 2001 due to financial difficulties and the relatively short lifetimes of the individual satellites. In 2007, Russia launched ## GLONASS-M platforms and began operating ## additional satellites that had been launched in late December 2006.