News Excerpt
Indian Space Research Organisation (ISRO) recently said that GSLV-F10 will launch geo imaging satellite, GISAT-1, from Satish Dhawan Space Centre in Sriharikota.

•    GISAT-1 or Geo Imaging Satellite-1 is India’s first earth imaging satellite in a geostationary orbit.
•    A satellite in geostationary orbit (about 36,000 km above earth) has an orbital period equal to earth’s rotational period.

    The GSLV flight will have a four-metre diameter ogive-shaped payload fairing being flown for the first time. A payload fairing is a nose cone used by a spacecraft for protection against dynamic pressure and aerodynamic heating during launch.
    After the launch, the earth observation satellite will use its on-board propulsion system to reach its final geostationary transfer orbit of around 36,000 km. All Indian earth observation satellites have been placed somewhere around 600 km orbits so far and circle the earth pole to pole.
    The orbital slot where GISAT-1 will operate is 93.5° E. This means that it will be collocated with Insat 3A, Insat 4B and GSat 15.
    The GISAT-1 has a lifespan of 7 years.
    The earth observation satellite weighs 2,275 kg.
    The main equipment it is carrying is the multi- and hyper-spectral imager along with the 700 mm Ritchey-Chretien telescope to carry out its function of earth observation and data collection.
    Also it has a high resolution camera.
    It is powered by a deployable solar array and batteries.
    GISAT is built on a modified I-1K (I-1000) Bus.

How will GISAT-1 work?
    GISAT carries a high resolution camera. The imaging payload consists of multi-spectral (visible, near infra-red and thermal), multi-resolution from 50 m to 1.5 km.
    This means that GISAT-1 will be able to send a selected sector-wise image every 5 minutes and an image of the entire Indian landmass every 30 minutes at 50 m spatial resolution.
    The geo imaging satellite will help keep a check on natural hazards and disasters, keep a constant watch on the border areas, and monitor any geographical changes.
    It will be able to carry out rapid surveillance. It will rotate the earth and return the same spot every two hours and when needed, it can spend a longer time on certain areas.

What all will GISAT-1 carry as its payload?
The GISAT payload consists of:
    700 mm Ritchey-Chretien telescope based on the design of Cartosat 2
    Array detectors in VNIR, SWIR and LWIR bands
o    High-resolution multi-spectral VNIR (HRMX - VNIR): 50 m resolution
o    High-resolution multi-spectral (HRMX - LWIR): 1.5 km resolution
o    Hyper-spectral VNIR: 320 m and 192 m resolution
o    Hyper-spectral SWIR: 320 m and 192 m resolution
o    Data handling system and camera electronics
    Transmit antenna system which is electronically steerable
    High agility platform to enable large payload steering requirements

Benefits of GISAT-1
    It will help to obtain spectral signatures of agriculture, forestry, mineralogy, disaster warning, cloud properties, snow, glaciers and oceanography.
    Facilitates near real time observation of the Indian sub-continent, under cloud free condition, at frequent intervals.
    Helps quick monitoring of natural disasters.
    Keep a constant watch on borders.
    Monitor any changes in the geographical condition of the country.

The state-of-the-art earth observation satellite GISAT-1 will thus operate from a geostationary orbit or a fixed spot and provide near to real-time observation data on the Indian subcontinent at frequent intervals under cloud-free conditions. While GISAT-1 is the first ISRO satellite to be launched in 2020, ISRO is planning the launch of 10 more satellites which would boost space and border surveillance, and crack down on terrorist infiltration.