UPSC Prelims 2023 Q57: Satellite Navigation Systems — Explained
Which one of the following countries has its own Satellite Navigation System?
- Australia
- Canada
- Israel
- Japan
Answer: (d) Japan
Statement-wise explanation
- a: incorrect — Australia does not run its own navigation satellite constellation. Receivers there use other countries' systems such as GPS (USA) and Galileo (EU). Australia's work with New Zealand on SouthPAN is an augmentation service. It corrects signals from other systems and has no navigation satellites of its own.
- b: incorrect — Canada has no national satellite navigation system. It depends on GPS and other foreign constellations. None of the global systems (GPS, GLONASS, Galileo, BeiDou) or the regional ones (NavIC, QZSS) belongs to Canada.
- c: incorrect — Israel builds and launches its own satellites, such as the Ofek reconnaissance series, but it has no satellite navigation system. Having launch capability or spy satellites is a different thing from running a positioning constellation.
- d: correct — Japan runs the Quasi-Zenith Satellite System (QZSS), also called 'Michibiki'. The Cabinet Office of Japan owns it. It has worked as a four-satellite constellation since November 2018 and is being expanded to seven satellites. It is a regional system that covers Japan and the Asia-Oceania region and works alongside GPS.
How to eliminate
Elimination tricks do not help much here, so you need to know the fact. There are only six national or regional satellite navigation systems: GPS (USA), GLONASS (Russia), Galileo (EU), BeiDou (China), NavIC (India) and QZSS (Japan). If you remember this list, Japan is the only listed country that appears in it. A partial clue: Japan is the only option with a large independent space programme (JAXA, H-II/H3 rockets), which makes it the most likely owner. Israel is a trap, because it launches its own satellites. But launching satellites does not mean running a navigation system.
Know more
Satellite navigation works through a constellation of satellites that keep broadcasting precise time signals. A receiver measures its distance from at least four satellites and works out its position and the exact time. Systems are either global (cover the whole Earth) or regional (cover one area, with fewer satellites, often in geosynchronous orbits).
| System | Owner | Type |
|---|---|---|
| GPS | USA | Global |
| GLONASS | Russia | Global |
| Galileo | European Union | Global |
| BeiDou | China | Global |
| NavIC (IRNSS) | India | Regional |
| QZSS (Michibiki) | Japan | Regional |
NavIC was built by ISRO with 7 satellites: 3 in geostationary orbit and 4 in inclined geosynchronous orbit. It covers India and up to 1,500 km beyond its borders, with position accuracy better than 20 m. It offers a Standard Positioning Service for civilians and an encrypted Restricted Service for strategic users. The International Maritime Organization recognises it as part of the World-Wide Radio Navigation System.
QZSS uses highly inclined orbits shaped like a figure of eight, so a satellite stays nearly overhead (near the 'zenith') above Japan. This helps in cities with tall buildings and in mountain valleys, where low satellites are blocked.
Augmentation systems are a different category. A Satellite-Based Augmentation System (SBAS) corrects GPS errors for aviation but has no navigation constellation of its own. Examples: India's GAGAN (ISRO and AAI), the US WAAS, Europe's EGNOS and Japan's MSAS. UPSC can use this distinction to set traps: a country with an SBAS does not have its own navigation system.
In the news
In 2022–23, NavIC was often in the news. The government pushed smartphone makers to support NavIC, ISRO added a civilian L1-band signal, and second-generation NVS satellites were being prepared. Comparing NavIC with other national systems such as Japan's QZSS was a natural way to frame a question.
NCERT Concepts to Revise
- Global navigation satellite system: The question asks which country owns a GNSS-type system, so you need to know what counts as one.
- NavIC: NavIC is India's regional system and the natural reference point for comparing other countries' regional navigation systems.
- Global Positioning System: GPS is the US system that most countries without their own constellation depend on.
- GAGAN: GAGAN shows that augmenting GPS is different from owning a satellite navigation constellation.