IRNSS, GAGAN, GSAT, ASTROSAT

Indian Regional Navigation Satellite System (IRNSS)

• With an investment of 1420 Cr, 7 Satellites to be put in space by ISRO
• Will cover India + 1,500 km beyond its borders
• 3 satellites will be put in geostationary orbit + 4 satellites in pairs in two inclined geosynchronous orbits
• From the ground, these satellites will appear to travel in figures of ‘8’ during the course of a day
• Will be at a height of about 36,000 km, launched from Satish Dawan Space Centre in Sriharikota
• Will need a special receiver equipment to use navigation data, standard GPS receiver will not work

At present only two countries have fully functional global navigation systems

IRNSS Scientific principle

Microwaves

• Use two microwave frequency bands: L5 and S which travel at speed of light.
• Receiver will calculate the delay between microwave’s transmission & its reception, thus we get coordinates on earth.

Atomic Clocks

• For above microwave-calculation, Satellites have to periodically transmit their precise position in orbit with exact time, hence, they need to carry extremely accurate clocks with long shelf-life.
• Therefore, Each IRNSS satellite is equipped with rubidium atomic clocks, to keep precise time.

Services

• Will provide two kinds of services viz. Standard Positioning Services, available to all users, and an encrypted service, provided only to authorized users
• IRNSS System is expected to provide a position accuracy of better than 20 m in the primary service area
• To be able to use the IRNSS satellites, ISRO have to launch at least four of the seven planned IRNSS satellites

Global Positioning System Aided Geo Augmented Navigation System (GAGAN)

• A joint effort by the ISRO & Airports Authority Of India (AAI) for civil aviation purposes
• Aimed to help Air traffic control and helps pilots fly / land aircrafts in bad weather
• Depends on GPS (American navigation system)

India has become 4^th nation after US, Europe & Japan to have inter-operable Satellite Based Augmentation System (SBAS) & 1^st in the world to serve the equatorial region

Working Pattern – GAGAN

• Works with the help of 3 Geostationary Satellites viz. GSAT-8, GSAT-10 and GSAT-15
• works by augmenting and relaying data from GPS satellites with the help of augmentation satellites and earth-based reference stations
• GAGAN system corrects any anomalies in the position data and gives accurate routes, landing guidance and time saving information to the pilots
• system would be available for the member states of the South Asian Association for Regional Cooperation (SAARC)
• It will be able to help pilots to navigate in the Indian airspace by an accuracy of 3 m

Major Benefits of GAGAN

• Improved efficiency,
• Direct routes
• Increased fuel savings
• Significant cost savings

Major drawback [arr]  only those aircraft that are fitted with satellite-based wide area augmentation system (SBAS) will be able to use the new technology
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GSAT 16

• INSAT-3E is a communication satellite that powers DD & private TV channels, internet & radio signals.
• INSAT-3E is getting old and outdated, even stopped working in March 2014, after serving for almost a decade, hence need to be replaced with GSAT-16
• GSAT 16 is configured to carry a total of 48 communication transponders, the largest number of transponders carried by a communication satellite developed by ISRO so far
• The designed on-orbit operational life of GSAT-16 is 12 years.
• Placed in Geosynchronous Transfer Orbit at 55 degrees East longitude by European Ariane-5 launcher

GSAT 6 

• It is aimed at primarily benefiting the country’s strategic and social applications
• Has life period of nine years & will povide S-band communication services in the country
• It includes a first-of-its-kind S-Band antenna with a diameter of six meter. This is the largest antenna ISRO has ever made for a satellite.
• It will offer a Satellite Digital Multimedia Broadcasting (S-band) service, via mobile phones and mobile video/audio receivers for vehicles.

ASTROSAT

• India’s 1^st dedicated astronomy multi-wavelength satellite, aimed at studying distant celestial objects
• ASTROSAT will observe universe in the optical, Ultraviolet, low and high energy X-ray regions of the electromagnetic spectrum
• 1^st mission to be operated as a space observatory by ISRO

Scientific objectives of ASTROSAT

• To understand high energy processes in binary star systems containing neutron stars and black holes
• Estimate magnetic fields of neutron stars
• Study star birth regions and high energy processes in star systems lying beyond our galaxy
• Detect new briefly bright X-ray sources in the sky
• Perform a limited deep field survey of the Universe in the Ultraviolet region