Infrastructure
Positioning, Navigation, and Timing (PNT) Satellites
2013 – GPS
To many, all satellite-based navigation is synonymous with the term “Global Positioning System” or “GPS.” However, this acronym only refers to one specific network: the U.S. Navigation Signal Timing and Ranging Global Positioning System (NAVSTAR-GPS). Developed by the U.S. Air Force (USAF), GPS became fully operational in 1995, and remained the only fully operational global satellite-based navigation network for several years. GPS provides global coverage with ## active satellites in MEO plus a number of in-orbit backups. The USAF currently maintains ## GPS satellites, along with ## to ## decommissioned satellites that can be reactivated as needed.
2012 – Positioning, Navigation, and Timing Systems
Note: This exhibit is from The Space Report 2013. Please refer to this year’s exhibits for the most current data as numbers may have been revised since this edition was published.
2012 – QZSS
Japan is creating the Quasi-Zenith Satellite System (QZSS), consisting of ## or ## satellites in a quasi-zenith orbit, and ## satellites in GEO to be operated by JAXA. This network will supplement its signals with those of the GPS network and, by using a tailored GEO orbit, will provide improved positioning performance in urban and mountainous regions. These GEO satellites will not be fixed over the Equator like typical FSS satellites but will regularly move north and south in relation to the Equator, making them easier to be seen from those areas where line-of-sight visibility to GPS can be difficult.
2012 – IRNSS
The Indian Regional Navigation Satellite System (IRNSS) will include ## satellites providing coverage primarily for South Asia. Like the Japanese system, ## of the ## will be in non-equatorial GEO, while ## will be in traditional GEO. The first satellite is scheduled to be launched in early 2013. India also has a GPS augmentation system called GPS-Aided Geo Augmented Navigation (GAGAN, which is Hindi for “sky”), designed to improve air navigation in India. In September 2012, the second of three GAGAN payloads was put in orbit aboard the GSAT-10 satellite.
2012 – Galileo
Europe also has made strides in developing its PNT system, Galileo. A joint initiative between the European Commission (EC) and ESA, the Galileo constellation will consist of ## operational satellites and ## in-orbit spares flying in MEO. The initial Galileo constellation is expected to be in place between 2014 and 2016. In October 2012, Europe launched the ## and ## Galileo in-orbit validation (IOV) satellites, joining ## more IOV satellites that were deployed one year earlier. Once activated, this ##-satellite validation fleet, built by Astrium, will demonstrate Galileo’s ability to provide highly precise, three-dimensional positioning.
2012 – BeiDou
Since 2000, China has been building its own PNT system, known as BeiDou. In December 2011, the Chinese government announced that its initial services—location data and SMS messaging—commenced for users within China. The two-way nature of this system allows the Chinese government to track the position of terrestrial BeiDou users, enabling applications such as asset tracking. Basic services to surrounding regions in Asia were scheduled to commence in 2012.
2012 – GLONASS
After a 15-year hiatus, Russia’s GLONASS PNT system returned to fully operational status in 2011, re-establishing full global coverage. The GLONASS constellation was started by the Soviet Union in 1982 and was briefly operational in 1996 after its ## satellite was deployed. However, due in part to the Russian financial crisis in the 1990s, funding to maintain the network evaporated and it fell into disrepair. Without replacements, the fleet had only ## functioning satellites by 2002.
2012 – GPS
To many consumers, all satellite-based navigation is synonymous with the term “GPS,” but 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 by the USAF and, until recently, was the only fully operational global satellite-based navigation network that supported civilian and commercial use. Operational since 1995, the system uses at least ## active satellites in MEO to provide global coverage while maintaining others in orbit as backups. The Air Force currently maintains ## GPS satellites, plus ## to ## decommissioned satellites that can still be reactivated as needed.
Infrastructure: Space Infrastructure – TSR 2012
2011 – Positioning, Navigation, and Timing Systems
Note: This exhibit is from The Space Report 2012.