ISRO & Earth Observation | Science & Technology for UPSC 2024 (Pre & Mains) PDF Download

 Page 1


 
ISRO & Earth Observation 
•GAGAN 
?Acronym for  GPS  Aided  GEO  Augmented  Navigation. It is a Space Based Augmentation  System 
(SBAS) jointly developed by  ISRO  and  AAI  to provide the best possible navigational services over 
Indian FIR (Flight Information Region) with the capability of expanding to neighbouring FIRs 
? SBAS is a wide area augmentation system that provides augmented accuracy and integrity to a 
Global Navigation Satellite Systems (GNSS) navigation signal such as GPS. An SBAS provides 
improved service availability over a wide area and is a more reliable navigation service than 
GNSS alone. This system uses ground monitoring stations spread across a wide area and 
provides signals from satellites to support high availability operations from an enroute through 
to precision approach over a large geographic area 
?GAGAN is a system of satellites and ground stations that provide GPS signal corrections, giving you 
better position accuracy 
?GPS alone does not meet the ICAOs navigational requirements for accuracy, integrity and 
availability. GAGAN corrects for GPS signal errors caused by Ionospheric disturbances, timing and 
satellite orbit errors and also it provides vital information regarding the health of each satellite 
?Services Offered 
? Aviation, Forest management, Railways signalling, Scienti?c Research for Atmospheric Studies, 
Natural Resource and Land Management, Location based services, Mobile, T ourism.  
?It is the ?rst Satellite-Based Augmentation System in the world which has been certi?ed for 
approach with vertical guidance operating in the equatorial ionospheric region  
?It is a system to improve the accuracy of a global navigation satellite system (GNSS) receiver by 
providing reference signals. Its goal is to provide a navigation system to assist aircraft in accurate 
landing over the Indian airspace and in the adjoining area and applicable to safety-to-life civil 
operations 
? It covers the area from Africa to Australia and has expansion capability for seamless navigation 
services across the region 
?Airports Authority of India (AAI) and Indian Space Research Organization (ISRO) have collaborated 
to develop the GPS Aided Geo Augmented Navigation (GAGAN) as a regional Satellite Based 
Augmentation System (SBAS) 
?It makes airline operations more ef?cient and effective, increase air safety, and fuel ef?ciency.  
?
Further, with vertical guidance at runways, a signi?cant cost will be saved due to withdrawal of 
ground aids and reduced workload of airline crew and traf?c controllers 
?One essential component of the GAGAN project is the study of the ionospheric behaviour over the 
Indian region. GAGAN ionospheric algorithm was developed by ISRO. This makes India the third 
country in the world which has such precisionapproach capabilities 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 2


 
ISRO & Earth Observation 
•GAGAN 
?Acronym for  GPS  Aided  GEO  Augmented  Navigation. It is a Space Based Augmentation  System 
(SBAS) jointly developed by  ISRO  and  AAI  to provide the best possible navigational services over 
Indian FIR (Flight Information Region) with the capability of expanding to neighbouring FIRs 
? SBAS is a wide area augmentation system that provides augmented accuracy and integrity to a 
Global Navigation Satellite Systems (GNSS) navigation signal such as GPS. An SBAS provides 
improved service availability over a wide area and is a more reliable navigation service than 
GNSS alone. This system uses ground monitoring stations spread across a wide area and 
provides signals from satellites to support high availability operations from an enroute through 
to precision approach over a large geographic area 
?GAGAN is a system of satellites and ground stations that provide GPS signal corrections, giving you 
better position accuracy 
?GPS alone does not meet the ICAOs navigational requirements for accuracy, integrity and 
availability. GAGAN corrects for GPS signal errors caused by Ionospheric disturbances, timing and 
satellite orbit errors and also it provides vital information regarding the health of each satellite 
?Services Offered 
? Aviation, Forest management, Railways signalling, Scienti?c Research for Atmospheric Studies, 
Natural Resource and Land Management, Location based services, Mobile, T ourism.  
?It is the ?rst Satellite-Based Augmentation System in the world which has been certi?ed for 
approach with vertical guidance operating in the equatorial ionospheric region  
?It is a system to improve the accuracy of a global navigation satellite system (GNSS) receiver by 
providing reference signals. Its goal is to provide a navigation system to assist aircraft in accurate 
landing over the Indian airspace and in the adjoining area and applicable to safety-to-life civil 
operations 
? It covers the area from Africa to Australia and has expansion capability for seamless navigation 
services across the region 
?Airports Authority of India (AAI) and Indian Space Research Organization (ISRO) have collaborated 
to develop the GPS Aided Geo Augmented Navigation (GAGAN) as a regional Satellite Based 
Augmentation System (SBAS) 
?It makes airline operations more ef?cient and effective, increase air safety, and fuel ef?ciency.  
?
Further, with vertical guidance at runways, a signi?cant cost will be saved due to withdrawal of 
ground aids and reduced workload of airline crew and traf?c controllers 
?One essential component of the GAGAN project is the study of the ionospheric behaviour over the 
Indian region. GAGAN ionospheric algorithm was developed by ISRO. This makes India the third 
country in the world which has such precisionapproach capabilities 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?GAGAN will provide bene?ts beyond aviation to all modes of transportation, including maritime, 
highways, railroads and public services such as defense services, security agencies, telecom industry 
and personal users of position location applications 
?Difference between GPS and GAGAN 
? The GPS is core constellation of satellites providing signals from space transmitting positioning 
and timing data. The GAGAN is an augmentation system which augments the GPS constellation 
by improving Accuracy, Availability, Continuity and Integrity. This is achieved by sending 
corrections and integrity information for GPS satellites through geostationary satellites to its 
users in the pre-de?ned service volume 
•
IRNSS or NavIC 
?Indian Regional Navigation Satellite System is a set of satellites which together can provide India a 
regional positioning system similar to the GPS. According to the ISRO website, the system is 
designed to give position accuracy better than 20 metres to users in its primary coverage area 
?It can also service regions extending up to 1500 km around India's boundary 
?It will work through a constellation of seven satellites inclined at 29 degrees to the equator  
?IRNSS will provide two types of services, namely,  
? Standard Positioning Service (SPS) which is provided to all the users and  
? Restricted Service (RS), which is an encrypted service provided only to the authorised users 
? The IRNSS System is expected to provide a position accuracy of better than 20 m in the primary 
service area 
?There are currently seven IRNSS satellites (1A to 1G) in orbit 
? A, B, F, G are placed in a geosynchronous orbit, which means they seem to be at a ?xed location 
above the Earth and they orbit along with the Earth 
?
The remaining three, C, D, E, are located in geostationary orbit-they seem to be at a ?xed 
location above the Earth along the equator and orbit along with the Earth 
?The satellites help not just in land navigation but also in marine and aerial navigation. The data from 
these satellites can be used to give vehicle drivers visual and voice navigation assistance. They also 
help in disaster management and in proper time-keeping 
?Difference between GPS, Glonass and NavIC 
? GPS is the American Satellite system which uses 32 satellites orbiting the earth to track and 
relay data to a variety of handheld devices. GPS uses a frequency known as L1. GLONASS is a 
Russian made satellite system largely on the lines of the GPS system. Glonass also has a global 
range and uses the L1 frequency for relay. The Indian Regional Navigation Satellite System is 
quite unique in comparison, with a satellite constellation size of 7 that track only India and an 
area of 1500 kms around it. The IRNSS satellite relays on the L5 band. With plans of an upgrade 
to an 11 satellite constellation, IRNSS could soon be accurate to 2m. Almost 10 times better 
than GPS average accuracy of 20 metres. At present, however, one can still expect an accuracy 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 3


 
ISRO & Earth Observation 
•GAGAN 
?Acronym for  GPS  Aided  GEO  Augmented  Navigation. It is a Space Based Augmentation  System 
(SBAS) jointly developed by  ISRO  and  AAI  to provide the best possible navigational services over 
Indian FIR (Flight Information Region) with the capability of expanding to neighbouring FIRs 
? SBAS is a wide area augmentation system that provides augmented accuracy and integrity to a 
Global Navigation Satellite Systems (GNSS) navigation signal such as GPS. An SBAS provides 
improved service availability over a wide area and is a more reliable navigation service than 
GNSS alone. This system uses ground monitoring stations spread across a wide area and 
provides signals from satellites to support high availability operations from an enroute through 
to precision approach over a large geographic area 
?GAGAN is a system of satellites and ground stations that provide GPS signal corrections, giving you 
better position accuracy 
?GPS alone does not meet the ICAOs navigational requirements for accuracy, integrity and 
availability. GAGAN corrects for GPS signal errors caused by Ionospheric disturbances, timing and 
satellite orbit errors and also it provides vital information regarding the health of each satellite 
?Services Offered 
? Aviation, Forest management, Railways signalling, Scienti?c Research for Atmospheric Studies, 
Natural Resource and Land Management, Location based services, Mobile, T ourism.  
?It is the ?rst Satellite-Based Augmentation System in the world which has been certi?ed for 
approach with vertical guidance operating in the equatorial ionospheric region  
?It is a system to improve the accuracy of a global navigation satellite system (GNSS) receiver by 
providing reference signals. Its goal is to provide a navigation system to assist aircraft in accurate 
landing over the Indian airspace and in the adjoining area and applicable to safety-to-life civil 
operations 
? It covers the area from Africa to Australia and has expansion capability for seamless navigation 
services across the region 
?Airports Authority of India (AAI) and Indian Space Research Organization (ISRO) have collaborated 
to develop the GPS Aided Geo Augmented Navigation (GAGAN) as a regional Satellite Based 
Augmentation System (SBAS) 
?It makes airline operations more ef?cient and effective, increase air safety, and fuel ef?ciency.  
?
Further, with vertical guidance at runways, a signi?cant cost will be saved due to withdrawal of 
ground aids and reduced workload of airline crew and traf?c controllers 
?One essential component of the GAGAN project is the study of the ionospheric behaviour over the 
Indian region. GAGAN ionospheric algorithm was developed by ISRO. This makes India the third 
country in the world which has such precisionapproach capabilities 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?GAGAN will provide bene?ts beyond aviation to all modes of transportation, including maritime, 
highways, railroads and public services such as defense services, security agencies, telecom industry 
and personal users of position location applications 
?Difference between GPS and GAGAN 
? The GPS is core constellation of satellites providing signals from space transmitting positioning 
and timing data. The GAGAN is an augmentation system which augments the GPS constellation 
by improving Accuracy, Availability, Continuity and Integrity. This is achieved by sending 
corrections and integrity information for GPS satellites through geostationary satellites to its 
users in the pre-de?ned service volume 
•
IRNSS or NavIC 
?Indian Regional Navigation Satellite System is a set of satellites which together can provide India a 
regional positioning system similar to the GPS. According to the ISRO website, the system is 
designed to give position accuracy better than 20 metres to users in its primary coverage area 
?It can also service regions extending up to 1500 km around India's boundary 
?It will work through a constellation of seven satellites inclined at 29 degrees to the equator  
?IRNSS will provide two types of services, namely,  
? Standard Positioning Service (SPS) which is provided to all the users and  
? Restricted Service (RS), which is an encrypted service provided only to the authorised users 
? The IRNSS System is expected to provide a position accuracy of better than 20 m in the primary 
service area 
?There are currently seven IRNSS satellites (1A to 1G) in orbit 
? A, B, F, G are placed in a geosynchronous orbit, which means they seem to be at a ?xed location 
above the Earth and they orbit along with the Earth 
?
The remaining three, C, D, E, are located in geostationary orbit-they seem to be at a ?xed 
location above the Earth along the equator and orbit along with the Earth 
?The satellites help not just in land navigation but also in marine and aerial navigation. The data from 
these satellites can be used to give vehicle drivers visual and voice navigation assistance. They also 
help in disaster management and in proper time-keeping 
?Difference between GPS, Glonass and NavIC 
? GPS is the American Satellite system which uses 32 satellites orbiting the earth to track and 
relay data to a variety of handheld devices. GPS uses a frequency known as L1. GLONASS is a 
Russian made satellite system largely on the lines of the GPS system. Glonass also has a global 
range and uses the L1 frequency for relay. The Indian Regional Navigation Satellite System is 
quite unique in comparison, with a satellite constellation size of 7 that track only India and an 
area of 1500 kms around it. The IRNSS satellite relays on the L5 band. With plans of an upgrade 
to an 11 satellite constellation, IRNSS could soon be accurate to 2m. Almost 10 times better 
than GPS average accuracy of 20 metres. At present, however, one can still expect an accuracy 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
of 10-12 metres?  
•
Beidou 
? Originally designed for Chinese military to reduce reliance on the US-owned GPS, Beidou has 
turned into a commercial opportunity as its coverage has expanded 
?Named after the Chinese word for the Big Dipper or Plough constellation [Ursa Major], Beidou has 
been in the works for over two decades but only became operational within China in 2000 and the 
Asia-Paci?c region in 2012 
? When complete in 2020, it will have a constellation of 35 satellites to provide global coverage 
?By the end of 2018, it will cover countries along the Belt and Road Initiative (BRI) - a massive China-
led infrastructure and trade programme, part of what it calls the "Space Silk Road" . Beidou already 
covers 30 countries involved with the BRI, including Pakistan, Laos and Indonesia 
? Pakistan has become the ?rst country to use the BeiDou system ending its reliance on the 
Global Positioning System 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 4


 
ISRO & Earth Observation 
•GAGAN 
?Acronym for  GPS  Aided  GEO  Augmented  Navigation. It is a Space Based Augmentation  System 
(SBAS) jointly developed by  ISRO  and  AAI  to provide the best possible navigational services over 
Indian FIR (Flight Information Region) with the capability of expanding to neighbouring FIRs 
? SBAS is a wide area augmentation system that provides augmented accuracy and integrity to a 
Global Navigation Satellite Systems (GNSS) navigation signal such as GPS. An SBAS provides 
improved service availability over a wide area and is a more reliable navigation service than 
GNSS alone. This system uses ground monitoring stations spread across a wide area and 
provides signals from satellites to support high availability operations from an enroute through 
to precision approach over a large geographic area 
?GAGAN is a system of satellites and ground stations that provide GPS signal corrections, giving you 
better position accuracy 
?GPS alone does not meet the ICAOs navigational requirements for accuracy, integrity and 
availability. GAGAN corrects for GPS signal errors caused by Ionospheric disturbances, timing and 
satellite orbit errors and also it provides vital information regarding the health of each satellite 
?Services Offered 
? Aviation, Forest management, Railways signalling, Scienti?c Research for Atmospheric Studies, 
Natural Resource and Land Management, Location based services, Mobile, T ourism.  
?It is the ?rst Satellite-Based Augmentation System in the world which has been certi?ed for 
approach with vertical guidance operating in the equatorial ionospheric region  
?It is a system to improve the accuracy of a global navigation satellite system (GNSS) receiver by 
providing reference signals. Its goal is to provide a navigation system to assist aircraft in accurate 
landing over the Indian airspace and in the adjoining area and applicable to safety-to-life civil 
operations 
? It covers the area from Africa to Australia and has expansion capability for seamless navigation 
services across the region 
?Airports Authority of India (AAI) and Indian Space Research Organization (ISRO) have collaborated 
to develop the GPS Aided Geo Augmented Navigation (GAGAN) as a regional Satellite Based 
Augmentation System (SBAS) 
?It makes airline operations more ef?cient and effective, increase air safety, and fuel ef?ciency.  
?
Further, with vertical guidance at runways, a signi?cant cost will be saved due to withdrawal of 
ground aids and reduced workload of airline crew and traf?c controllers 
?One essential component of the GAGAN project is the study of the ionospheric behaviour over the 
Indian region. GAGAN ionospheric algorithm was developed by ISRO. This makes India the third 
country in the world which has such precisionapproach capabilities 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?GAGAN will provide bene?ts beyond aviation to all modes of transportation, including maritime, 
highways, railroads and public services such as defense services, security agencies, telecom industry 
and personal users of position location applications 
?Difference between GPS and GAGAN 
? The GPS is core constellation of satellites providing signals from space transmitting positioning 
and timing data. The GAGAN is an augmentation system which augments the GPS constellation 
by improving Accuracy, Availability, Continuity and Integrity. This is achieved by sending 
corrections and integrity information for GPS satellites through geostationary satellites to its 
users in the pre-de?ned service volume 
•
IRNSS or NavIC 
?Indian Regional Navigation Satellite System is a set of satellites which together can provide India a 
regional positioning system similar to the GPS. According to the ISRO website, the system is 
designed to give position accuracy better than 20 metres to users in its primary coverage area 
?It can also service regions extending up to 1500 km around India's boundary 
?It will work through a constellation of seven satellites inclined at 29 degrees to the equator  
?IRNSS will provide two types of services, namely,  
? Standard Positioning Service (SPS) which is provided to all the users and  
? Restricted Service (RS), which is an encrypted service provided only to the authorised users 
? The IRNSS System is expected to provide a position accuracy of better than 20 m in the primary 
service area 
?There are currently seven IRNSS satellites (1A to 1G) in orbit 
? A, B, F, G are placed in a geosynchronous orbit, which means they seem to be at a ?xed location 
above the Earth and they orbit along with the Earth 
?
The remaining three, C, D, E, are located in geostationary orbit-they seem to be at a ?xed 
location above the Earth along the equator and orbit along with the Earth 
?The satellites help not just in land navigation but also in marine and aerial navigation. The data from 
these satellites can be used to give vehicle drivers visual and voice navigation assistance. They also 
help in disaster management and in proper time-keeping 
?Difference between GPS, Glonass and NavIC 
? GPS is the American Satellite system which uses 32 satellites orbiting the earth to track and 
relay data to a variety of handheld devices. GPS uses a frequency known as L1. GLONASS is a 
Russian made satellite system largely on the lines of the GPS system. Glonass also has a global 
range and uses the L1 frequency for relay. The Indian Regional Navigation Satellite System is 
quite unique in comparison, with a satellite constellation size of 7 that track only India and an 
area of 1500 kms around it. The IRNSS satellite relays on the L5 band. With plans of an upgrade 
to an 11 satellite constellation, IRNSS could soon be accurate to 2m. Almost 10 times better 
than GPS average accuracy of 20 metres. At present, however, one can still expect an accuracy 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
of 10-12 metres?  
•
Beidou 
? Originally designed for Chinese military to reduce reliance on the US-owned GPS, Beidou has 
turned into a commercial opportunity as its coverage has expanded 
?Named after the Chinese word for the Big Dipper or Plough constellation [Ursa Major], Beidou has 
been in the works for over two decades but only became operational within China in 2000 and the 
Asia-Paci?c region in 2012 
? When complete in 2020, it will have a constellation of 35 satellites to provide global coverage 
?By the end of 2018, it will cover countries along the Belt and Road Initiative (BRI) - a massive China-
led infrastructure and trade programme, part of what it calls the "Space Silk Road" . Beidou already 
covers 30 countries involved with the BRI, including Pakistan, Laos and Indonesia 
? Pakistan has become the ?rst country to use the BeiDou system ending its reliance on the 
Global Positioning System 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?Despite its technological sophistication, Beidou has a  supposed ?aw  - a two-way transmission 
process that involves satellites sending signals to earth and devices transmitting signals back. This 
can compromise accuracy and takes up more spectrum bandwidth. In contrast, GPS devices do not 
have to transmit signals back to the satellites 
?The positioning accuracy of the China's BeiDou Navigation Satellite System has reached 10 metres 
globally and ?ve metres in the Asia-Paci?c region?  
•SARAL (Satellite with ARGOS and ALTIKA) 
?Joint mission with France, named SARAL (Satellite for ALTIKA and ARGOS) for studying ocean from 
space using altimetry was successfully launched in 2013 
?It performs altimetric measurements designed to study ocean circulation and sea surface elevation 
•NISAR (NASA ISRO Synthetic Aperture Radar) 
?ISRO and NASA are jointly working on the NASA-ISRO Synthetic Aperture Radar (NISAR) mission 
to codevelop and launch a dual frequency synthetic aperture radar satellite by 2021 
?NASA is responsible for development of L -band SAR and ISRO is responsible for development of S-
band SAR. The L & S band SAR will be integrated with ISRO’s spacecraft and launched on-board 
India’s GSLV 
?Applications 
? Natural resources mapping & monitoring 
?
Estimating agricultural biomass over full duration of crop cycle 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 5


 
ISRO & Earth Observation 
•GAGAN 
?Acronym for  GPS  Aided  GEO  Augmented  Navigation. It is a Space Based Augmentation  System 
(SBAS) jointly developed by  ISRO  and  AAI  to provide the best possible navigational services over 
Indian FIR (Flight Information Region) with the capability of expanding to neighbouring FIRs 
? SBAS is a wide area augmentation system that provides augmented accuracy and integrity to a 
Global Navigation Satellite Systems (GNSS) navigation signal such as GPS. An SBAS provides 
improved service availability over a wide area and is a more reliable navigation service than 
GNSS alone. This system uses ground monitoring stations spread across a wide area and 
provides signals from satellites to support high availability operations from an enroute through 
to precision approach over a large geographic area 
?GAGAN is a system of satellites and ground stations that provide GPS signal corrections, giving you 
better position accuracy 
?GPS alone does not meet the ICAOs navigational requirements for accuracy, integrity and 
availability. GAGAN corrects for GPS signal errors caused by Ionospheric disturbances, timing and 
satellite orbit errors and also it provides vital information regarding the health of each satellite 
?Services Offered 
? Aviation, Forest management, Railways signalling, Scienti?c Research for Atmospheric Studies, 
Natural Resource and Land Management, Location based services, Mobile, T ourism.  
?It is the ?rst Satellite-Based Augmentation System in the world which has been certi?ed for 
approach with vertical guidance operating in the equatorial ionospheric region  
?It is a system to improve the accuracy of a global navigation satellite system (GNSS) receiver by 
providing reference signals. Its goal is to provide a navigation system to assist aircraft in accurate 
landing over the Indian airspace and in the adjoining area and applicable to safety-to-life civil 
operations 
? It covers the area from Africa to Australia and has expansion capability for seamless navigation 
services across the region 
?Airports Authority of India (AAI) and Indian Space Research Organization (ISRO) have collaborated 
to develop the GPS Aided Geo Augmented Navigation (GAGAN) as a regional Satellite Based 
Augmentation System (SBAS) 
?It makes airline operations more ef?cient and effective, increase air safety, and fuel ef?ciency.  
?
Further, with vertical guidance at runways, a signi?cant cost will be saved due to withdrawal of 
ground aids and reduced workload of airline crew and traf?c controllers 
?One essential component of the GAGAN project is the study of the ionospheric behaviour over the 
Indian region. GAGAN ionospheric algorithm was developed by ISRO. This makes India the third 
country in the world which has such precisionapproach capabilities 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?GAGAN will provide bene?ts beyond aviation to all modes of transportation, including maritime, 
highways, railroads and public services such as defense services, security agencies, telecom industry 
and personal users of position location applications 
?Difference between GPS and GAGAN 
? The GPS is core constellation of satellites providing signals from space transmitting positioning 
and timing data. The GAGAN is an augmentation system which augments the GPS constellation 
by improving Accuracy, Availability, Continuity and Integrity. This is achieved by sending 
corrections and integrity information for GPS satellites through geostationary satellites to its 
users in the pre-de?ned service volume 
•
IRNSS or NavIC 
?Indian Regional Navigation Satellite System is a set of satellites which together can provide India a 
regional positioning system similar to the GPS. According to the ISRO website, the system is 
designed to give position accuracy better than 20 metres to users in its primary coverage area 
?It can also service regions extending up to 1500 km around India's boundary 
?It will work through a constellation of seven satellites inclined at 29 degrees to the equator  
?IRNSS will provide two types of services, namely,  
? Standard Positioning Service (SPS) which is provided to all the users and  
? Restricted Service (RS), which is an encrypted service provided only to the authorised users 
? The IRNSS System is expected to provide a position accuracy of better than 20 m in the primary 
service area 
?There are currently seven IRNSS satellites (1A to 1G) in orbit 
? A, B, F, G are placed in a geosynchronous orbit, which means they seem to be at a ?xed location 
above the Earth and they orbit along with the Earth 
?
The remaining three, C, D, E, are located in geostationary orbit-they seem to be at a ?xed 
location above the Earth along the equator and orbit along with the Earth 
?The satellites help not just in land navigation but also in marine and aerial navigation. The data from 
these satellites can be used to give vehicle drivers visual and voice navigation assistance. They also 
help in disaster management and in proper time-keeping 
?Difference between GPS, Glonass and NavIC 
? GPS is the American Satellite system which uses 32 satellites orbiting the earth to track and 
relay data to a variety of handheld devices. GPS uses a frequency known as L1. GLONASS is a 
Russian made satellite system largely on the lines of the GPS system. Glonass also has a global 
range and uses the L1 frequency for relay. The Indian Regional Navigation Satellite System is 
quite unique in comparison, with a satellite constellation size of 7 that track only India and an 
area of 1500 kms around it. The IRNSS satellite relays on the L5 band. With plans of an upgrade 
to an 11 satellite constellation, IRNSS could soon be accurate to 2m. Almost 10 times better 
than GPS average accuracy of 20 metres. At present, however, one can still expect an accuracy 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
of 10-12 metres?  
•
Beidou 
? Originally designed for Chinese military to reduce reliance on the US-owned GPS, Beidou has 
turned into a commercial opportunity as its coverage has expanded 
?Named after the Chinese word for the Big Dipper or Plough constellation [Ursa Major], Beidou has 
been in the works for over two decades but only became operational within China in 2000 and the 
Asia-Paci?c region in 2012 
? When complete in 2020, it will have a constellation of 35 satellites to provide global coverage 
?By the end of 2018, it will cover countries along the Belt and Road Initiative (BRI) - a massive China-
led infrastructure and trade programme, part of what it calls the "Space Silk Road" . Beidou already 
covers 30 countries involved with the BRI, including Pakistan, Laos and Indonesia 
? Pakistan has become the ?rst country to use the BeiDou system ending its reliance on the 
Global Positioning System 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?Despite its technological sophistication, Beidou has a  supposed ?aw  - a two-way transmission 
process that involves satellites sending signals to earth and devices transmitting signals back. This 
can compromise accuracy and takes up more spectrum bandwidth. In contrast, GPS devices do not 
have to transmit signals back to the satellites 
?The positioning accuracy of the China's BeiDou Navigation Satellite System has reached 10 metres 
globally and ?ve metres in the Asia-Paci?c region?  
•SARAL (Satellite with ARGOS and ALTIKA) 
?Joint mission with France, named SARAL (Satellite for ALTIKA and ARGOS) for studying ocean from 
space using altimetry was successfully launched in 2013 
?It performs altimetric measurements designed to study ocean circulation and sea surface elevation 
•NISAR (NASA ISRO Synthetic Aperture Radar) 
?ISRO and NASA are jointly working on the NASA-ISRO Synthetic Aperture Radar (NISAR) mission 
to codevelop and launch a dual frequency synthetic aperture radar satellite by 2021 
?NASA is responsible for development of L -band SAR and ISRO is responsible for development of S-
band SAR. The L & S band SAR will be integrated with ISRO’s spacecraft and launched on-board 
India’s GSLV 
?Applications 
? Natural resources mapping & monitoring 
?
Estimating agricultural biomass over full duration of crop cycle 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
assessing soil moisture 
? monitoring of ?oods and oil slicks 
? coastal erosion, coastline changes and variation of winds in coastal waters 
?
assessment of mangroves 
? surface deformation studies due to seismic activities etc 
?The data obtained from NISAR mission is not meant for building climate resilience. However, the 
data acquired from this mission will be useful in developing certain applications, which include  
? identifying crevasses in the glaciers hidden by fresh snow, where human movement takes place, 
?
identifying the snowpack parameters as an input in Avalanche forecasts 
? studying Glacial Lake Outburst Floods (GLOF) hazards, and 
?
identifying inundated area due to ?oods/ cyclones
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!