Positioning, Navigation, and Timing (PNT) Satellites
The European Union’s Galileo constellation was scheduled to be operational in 2014, with ## satellites in use by the end of the year. Those plans had to be delayed when ## key Galileo satellites, Sat 5 and 6, were launched and then inserted into the wrong orbit in August 2014. Initially thought to be a lost cause, the Europeans proceeded in October 2014 on a plan to put Sat 5 in circular orbit, allowing the satellite to still be used for its navigation mission. Once the operators have confirmed the plan’s success with Sat 5, they will try implementing a similar plan for Sat 6.
Russia launched ## GLONASS satellites in 2014, maintaining a constellation of ## operational satellites. Russia also faced some challenges with GLONASS during 2014. On April 1, GLONASS satellites transmitted messages that reported the satellites’ positions with an error of around 200 kilometers (124 miles). The problem was resolved after about 11 hours, and although the outage did not seem to have major negative impacts on businesses relying on PNT services, some organizations are learning from the problems GLONASS faced and are moving toward systems using more than one PNT constellation.
The number of U.S. GPS satellites remained relatively unchanged from 2013, with ## orbiting the Earth. The composition of GPS satellite generations within the constellation changed, as the United States launched ## new GPS IIF satellites during 2014. Nearly a third of the current GPS constellation consists of the newer GPS IIF satellites. In October 2014, a Combined Launch Schedule Review Board (CLSRB) determined that the launches of GPS III satellites would be postponed from 2015 until 2017. The decision to delay the GPS III satellite upgrade took into account the good health of the current GPS constellation.
The military and commercial value of positioning, navigation, and timing (PNT) systems has gained such prominence that PNT systems are often considered to be critical infrastructure. The proliferation of smartphones and other consumer devices that rely on PNT services has spread this dependence… Thank you for visiting The Space Report! The Authoritative Guide to Global…
Note: The exhibit in this section is from The Space Report 2014. Please refer to this year’s exhibits for the most current data as numbers may have been revised since this edition was published.
Japan already employs a ##-satellite GPS-augmentation system called MSAS, which stands for the MTSAT (Multi-functional Transport Satellite) Satellite-based Augmentation System. The Japan Aerospace Exploration Agency (JAXA) is also creating the Quasi-Zenith Satellite System (QZSS), consisting of ## to ## quasi-GEO satellites that will address navigation issues specific to Japan’s geography. While these will be at similar altitudes as traditional GEO satellites, they will not actually be fixed over the Equator like typical FSS satellites.
Several other nations are developing or expanding their PNT or augmentation systems. The first satellite in the Indian Regional Navigation Satellite System (IRNSS) was launched in 2013. When complete, the network will include ## satellites to enhance PNT coverage over South Asia. ## of the ## will be in heavily inclined, non-equatorial GEO, while ## will be in traditional GEO. India also has a GPS augmentation system called GPS-Aided Geo Augmented Navigation (GAGAN), designed to improve air navigation in India.
A joint initiative between the European Commission (EC) and ESA, the Galileo constellation will consist of ## operational satellites in MEO. Europe launched ## in-orbit validation (IOV) spacecraft between 2011 and 2012 for positioning tests and technology validation. In November 2013, the IOV network enabled Galileo to successfully track a test aircraft flying over the Netherlands, the first time that the European agency has been able to track a moving aircraft using only the Galileo system. Initially, Galileo’s Open Service—freely accessibly PNT signals for mass-market devices such as smartphones and automobile navigation systems—is planned to be operational in 2014, although the launch of the first ## satellites has been delayed.
In 2011, China became the third nation to declare a PNT system operational, with the announcement that its BeiDou system was able to provide location data and SMS messaging for users within China. In late 2012, The China Satellite Navigation Office published the complete interface control document for the system, enabling international manufacturers to build BeiDou-compatible receivers. Basic services to surrounding regions in Asia were enabled in 2012, and by mid-2013, Chinese efforts to aggressively promote BeiDou as a viable alternative to GPS and GLONASS were well underway.
The second global PNT system to become operational was Russia’s GLONASS constellation, which was started by the Soviet Union in 1976, and was briefly operational in 1996 after the deployment of its ## satellite. However, during the Russian financial crisis of the 1990s, program funding evaporated, and GLONASS fell into disrepair as satellites reached the end of their design life and were not replaced. In 2001, President Vladimir Putin ordered a 10-year, $## billion modernization program of GLONASS, resulting in an upgrade and replenishment of the satellite constellation, which was completed in 2011.