China successfully launched the last satellite of its BeiDou Navigation Satellite System (BDS), touted to be a competitor to the Global Positioning System (GPS) of the US, taking another step to becoming a major space power.

The satellite was launched on June 23 from the Xichang Satellite Launch Centre in southwest China's Sichuan Province.

The satellite, the 55th in the family of BeiDou that means “Big Dipper” in Chinese, was successfully sent into space by a Long March-3B carrier rocket, according to the China Satellite Navigation Office, state-run CGTN reported. 

The launch will mark the completion of the country’s domestically developed BeiDou network, one of the four global navigation networks alongside with the US-owned GPS, Russia’s GLONASS and the European Union’s Galileo.

BeiDou Navigation Satellite System

The BeiDou Navigation Satellite System (BDS) has been constructed and operated by China with an eye to the needs of the country’s national security. 

The BDS provides all-time, all-weather and high-accuracy positioning, navigation and timing services.

In the late 20th century, China started to explore a path to develop a navigation satellite system suitable for its national conditions, and gradually formulated a three-step strategy of development. 

The idea to develop BeiDou took shape in the 1990s as China’s military sought to reduce its reliance on GPS, which is run by the US Air Force.

The construction of the BDS-1 officially started in 1994. The first generation of the BeiDou system made China the third country after the US and Russia to have a satellite navigation system. 

By 2000, the construction of the BDS-1 was completed and started providing positioning, navigation, timing (PNT) and messaging services to domestic users in China 

The construction of BDS-2, designed to provide navigation services over the broader Asia-Pacific region, was completed in 2012.

In 2015, China began deploying BDS-3 satellites aimed at global coverage.

The latest GEO satellite is the 55th BDS system, and will work with other members of the network, allowing global users to access high-accuracy navigation, positioning and timing as well as communication services, an official report said. 

Compared to previous generation series, the constellation of BDS-3 with an array of 30 satellites flying on three different orbit planes — three at the GEO, three at the inclined geosynchronous orbits, and 24 at the medium Earth orbit — have higher bandwidth.

They enable enhanced communication capability and carrying more accurate and stable domestically developed atomic clocks to improve the precision of timing and navigation services, a report said.

The BDS is mainly comprised of three segments: 

1) The space segment: It is a hybrid navigation constellation consisting of geo, inclined geosynchronous orbits (IGSO) and medium earth orbit (MEO) satellites.

2) The ground segment: It consists of various ground stations, including master control stations, time synchronisation/uplink stations, and monitoring stations.

3) The user segment: It consists of various kinds of BDS basic products, including chips, modules and antennae, as well as terminals, application systems and application services, which are compatible with other systems.

Global Positioning System

The Global Positioning System (GPS) is a US-owned utility that provides users with positioning, navigation, and timing (PNT) services. This system consists of three segments: the space segment, the control segment, and the user segment. The US Air Force develops, maintains, and operates the space and control segments.

The GPS space segment consists of a constellation of satellites transmitting radio signals to users. The US is maintaining the availability of at least 24 operational GPS satellites.

GPS has its origins in the Sputnik-era when scientists were able to track the satellite with shifts in its radio signal known as the “Doppler Effect”. The US Navy conducted satellite navigation experiments in the mid 1960s to track US submarines carrying nuclear missiles. With six satellites orbiting the poles, submarines were able to observe the satellite changes in Doppler and pinpoint the submarine’s location within a matter of minutes.

In the early 1970s, the Department of Defence (DoD) wanted to ensure a robust, stable satellite navigation system would be available. Embracing previous ideas from Navy scientists, the DoD decided to use satellites to support their proposed navigation system. DoD then followed through and launched its first Navigation System with Timing and Ranging (NAVSTAR) satellite in 1978. The 24 satellite system became fully operational in 1993.

Today, GPS is a multi-use, space-based radionavigation system owned by the US government and operated by the US Air Force to meet national defence, homeland security, civil, commercial, and scientific needs. GPS currently provides two levels of service: Standard Positioning Service (SPS) and Precise Positioning Service (PPS). Access to the PPS is restricted to US Armed Forces, US federal agencies, and selected allied armed forces and governments. The SPS is available to all users on a continuous, worldwide basis, free of any direct user charges. 

Russia’s GLONASS

The first proposal to use satellites for navigation was made by V.S. Shebashevich in 1957. This idea was born during the investigation of the possible application of radio-astronomy technologies for aeronavigation. Further investigations were conducted in a number of the Soviet institutions to increase the accuracy of navigation definitions, global support, daily application and independence from weather conditions.

The “Cicada” space navigation system (and its “Cicada-M” modernisation) was designed for navigation support of military users and had been in use since 1976.

Flight tests of the Russian high orbit satellite navigation system, called Global Navigation Satellite System (GLONASS), were started in October, 1982 with the launch of “Kosmos-1413” satellite. The GLONASS system was formally declared operational in 1993. In 1995 it was brought to a fully operational constellation (24 GLONASS satellites of the first generation). 

Since 2012, the GLONASS system has been moving in the direction of efficient PNT task solving for the benefit of defence, security and social and economic development of the country.

European Union’s Galileo

Galileo is the European Union’s Global Satellite Navigation System (GNSS). Like the other global systems, Galileo provides radio signals for position, navigation and timing purposes. 

On December 15, 2016, the Declaration of Initial Services marked the beginning of Galileo’s operational phase. Galileo is a joint initiative of the European Commission, the European GNSS Agency and the European Space Agency. The Galileo programme is owned by the European Union (EU).

Sometimes called the ‘European GPS’, Galileo is a programme under civilian control and its data can be used for a broad range of applications. It is autonomous but also interoperable with existing satellite navigation systems. The Galileo constellation consists of 26 satellites.

The services are managed by the European GNSS Agency (GSA), based in Prague, Czech Republic.

Many sectors of the European economy rely on precise localisation. The market for satellite navigation services has been growing steadily and is expected to be worth €250 billion per year by 2022. Around 7 per cent of the EU economy is dependent on the availability of global navigation satellite signals. This includes transport, logistics, telecommunications and energy. Independent studies show that Galileo will deliver around €90 billion to the EU economy over the first 20 years of operations. This includes direct revenues for the space, receivers, and applications industries, and indirect revenues for society such as more effective transport systems, more effective rescue operations, etc.