Friday, 28 August 2015

GSLV D6 and GSAT-6

Why in news?

ISRO has successfully placed a GSAT-6 communication satellite on board GSLV D6 in the intended orbit which will be eventually manoeuvred into the final geostationary orbit.


Details:

Source: The Hindu



About GSLV D6:


  • GSLV, or Geosynchronous Satellite Launch Vehicle, is an advanced launch vehicle that can be used to carry satellites heavier than 2000-kg, even those weighing up to 5000-kg, into space. 
  • ISRO has been banking on this to realise its future projects to explore deep space, far beyond even Mars where it has already reached. 
  • Technical details:
    • 3-stage heavy weight rocket: 
      • First stage : fired with solid fuel while the four strap-on motors by liquid fuel. 
      • Second stage: liquid fuel
      • Third stage: cryogenic engine - 
        • indigenous cryogenic upper stage (CUS)
    • Cryogenics:
      • GSLV’s higher capabilities, as compared to the PSLV or Polar Satellite Launch Vehicle that has made 28 successful launches in a row, is made possible by a the cryogenic part of the three-stage engine. 
        • Cryogenics is the science of extremely low temperatures. 
        • The cryogenic engine uses liquid oxygen and liquid hydrogen as propellants. 
          • Oxygen liquifies at -183 degree centigrade while hydrogen exists in liquid stage below -253 degree centigrade. 
          • The cryogenic engine is extremely efficient, providing greater thrust for every kilogram of propellant used as compared to solid or “earth-storable” liquid propellants. 
            • But it is also a highly complex system owing to the extremely low temperatures that need to be maintained. 
  • Success:
    • The first successful flights of GSLV used Russian-made cryogenic engines, including the GSLF-F04 that carried the heaviest-ever satellite launched from the Indian shores, the INSAT-4CR that weighed 2130 kg, 13 kg more than GSAT-6. 
    • This launch is the 9 time ISRO was using GSLV rocket, this is the third time the rocket was being launched with indigenous cryogenic upper stage.
    • ISRO’s initial attempts to use its own cryogenic engine in the GSLV resulted in failure. 
    • It was only in January last year that the first GSLV with an indigenous cryogenic-stage engine made a successful flight.

About GSAT-6:

  • The GSAT-6 satellite that will beam communication signals from 
    • 5 slots in the S-band and 
    • 1 in the C-band 
      • for “strategic purposes” will be placed in the geostationary orbit.
  • GSAT-6 will provide S-band communication services in the country.
    • This system also includes a first-of-its-kind S-Band unfurlable antenna with a diameter of six metre. This is the largest antenna ISRO has ever made for a satellite.
  • In this orbit, 36000 km above the earth’s surface, a satellite appears stationary from any point in the earth because the time it takes to go around the orbit is the same as earth’s rotational period. 
  • Ground stations can remain permanently pointed to the satellites in this case and do not need to move to track them. 
  • The launch vehicle will carry the GSAT-6 satellite till the geostationary transfer orbit (GTO) from where the satellite will use its own propellants to make its way to the geostationary orbit. 
  • GSAT-6 is the 25th communication satellite that India will put in the geostationary orbit and the 12th in the GSAT series. 
Significance:
  • GSLV-D6 flight is significant since it intends to continue the testing of CUS
  • Foreign exchange can be saved by launching communication satellites on its own
    • Currently done by European space agency Ariane.
  • More indigenisation --> more industries --> more jobs --> more employment --> more growth
  •  AlsothiithfirstimGSLrockewitaindigenouCUhacrossethtwo-tonnpayloamark
  • ISRO has not had a single launch failure in four and a half years, a fact that boosts the confidence level and morale of the scientific fraternity in the country. 
  • The record also buttresses the image ISRO commands in the realm of space launches, especially given that other global players are not very generous with technology transfers. 
Critical Analysis:
  • However, earning the ‘operational rocket’ tag for the GSLV-Mk-II following the two consecutive successful launches will not immediately mean much, as most of the communication satellites ISRO currently makes are beyond the GSLV-Mk-II’s two-tonne capability. 
  • India’s dependence on foreign space agencies to launch those heavier satellites will continue till the GSLV-Mk-III is tested and declared operational. 
  • The GSLV-Mk-II, at most, can save money on our own launches but it is not a revenue-earner yet. 
  • The INSAT-4A weighing over 3 tonnes was designed way back in 2005 by ISRO, and the GSLV-Mk-II has cleared 2 tonnes only a decade later. 
  • As global trends reflect an increase in the size of communication satellites and a reduction in the size of earth observation satellites, rocket-making should aim to match future requirements besides being cost-effective. 
  • For India, a developing country, every rupee spent has to be worth it
  • ISRO will require more flawless Mk-II launches to understand GSLV behaviour adequately and develop the requisite confidence and expertise. 
  • But the paucity of launch pads might still limit the process. 
  • While the Mars mission and the experimental crew capsule mission are feathers in ISRO’s cap, making rockets for satellites should be the priority
  • Even as ISRO expands its capabilities, how soon it would achieve true self-reliance will be a crucial factor.

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