Define History of GNSS.

The history of Global Navigation Satellite Systems (GNSS) is a testament to the evolution and collaboration of technologies developed to provide accurate positioning and navigation services worldwide. The journey of GNSS began in the mid-20th century and has since transformed into a critical component of various industries and daily life.

1. Transit System (1960s):
   The concept of GNSS originated with the United States Navy's Transit system, which became operational in the early 1960s. Transit used a constellation of low Earth orbit satellites to provide global positioning for maritime and military applications.

2. Navstar GPS (1970s-1980s):
   Building on the success of Transit, the United States Department of Defense developed the Global Positioning System (GPS) in the 1970s. The first GPS satellite was launched in 1978, and the system became fully operational in the 1980s. GPS marked a significant milestone in GNSS history, providing accurate and global navigation capabilities for both military and civilian users.

3. GLONASS (1970s-1980s):
   The Soviet Union initiated the development of its GNSS system, GLONASS (Global Navigation Satellite System), in the 1970s. GLONASS became fully operational in the 1980s, offering global coverage and serving both military and civilian purposes.

4. Galileo (2000s-2020s):
   The European Union and the European Space Agency launched the Galileo program to establish an independent European GNSS system. The first Galileo satellite was launched in 2005, and the constellation gradually expanded. As of my last knowledge update in January 2022, Galileo has been providing positioning services for various applications.

5. BeiDou (COMPASS) (2000s-2020s):
   China developed its GNSS system, BeiDou Navigation Satellite System (BDS), also known as COMPASS. The first BeiDou satellite was launched in 2000, and the system achieved global coverage with the completion of its constellation in the 2020s.

6. Regional Systems and Augmentations:
   In addition to global systems, various countries have implemented regional GNSS systems. Additionally, augmentation systems like WAAS (Wide Area Augmentation System) and EGNOS (European Geostationary Navigation Overlay Service) enhance the accuracy and reliability of GNSS signals for specific regions.

GNSS has become an integral part of daily life, contributing to navigation, transportation, agriculture, surveying, and countless other applications. The collaboration and interoperability among different GNSS constellations contribute to the resilience and global reach of satellite-based navigation systems.