INSAT-3DR

 The Indian Space Research Organisation's GSLV-F05 rocket successfully placed INSAT-3DR advanced weather satellite in the intended orbit.
The satellite is expected to provide a variety of meteorological services to the country.

About INSAT- 3DR:

• INSAT-3DR similar to INSAT-3D, is an advanced meteorological satellite of India configured with an imaging System and an Atmospheric Sounder.
• The significant improvements incorporated in INSAT-3DR are: a) Imaging in Middle Infrared band to provide night time pictures of low clouds and fog; b) Imaging in two Thermal Infrared bands for estimation of Sea Surface Temperature (SST) with better accuracy; c) Higher Spatial Resolution in the Visible and Thermal Infrared bands
• And, like its predecessor INSAT-3D, INSAT-3DR carries a Data Relay Transponder as well as a Search and Rescue Transponder.
• Thus, INSAT-3DR will provide service continuity to earlier meteorological missions of ISRO and further augment the capability to provide various meteorological as well as search and rescue services.
• INSAT-3DR has a lift-off mass of 2211 kg, which includes about 1255 kg of propellant.
• The propellant carried by INSAT-3DR is mainly required to raise the satellite from the Geosynchronous Transfer Orbit (GTO) to its final Geostationary Orbit and to maintain the satellite in its orbital slot during its life.
• The satellite has a solar array generating 1700 Watts of power.
• It was GSLV's 10th flight. It was GSLV's fourth flight with the desi cryogenic engine CE-7.5, with the first three being developmental flights.

Payloads:

• Multi-spectral Imager: It will generate images of the Earth from a geostationary altitude of 36,000 km every 26 minutes and provide information on parameters such as sea surface temperature, snow cover, cloud motion winds, among others.
• 19 channel sounder: It will provide information on the vertical profiles of temperature, humidity and integrated ozone.
• Data Relay Transponder: It will provide service continuity to ISRO’s previous meteorological missions.
• Search and Rescue payload: It can pick up and relay alert signals originating from the distress beacons of maritime, aviation and land-based users to the Indian Mission Control Centre (INMCC).

Indigenous cryogenic engine

• A Cryogenic rocket stage is more efficient and provides more thrust for every kilogram of propellant it burns compared to solid and earth-storable liquid propellant rocket stages.
• Specific impulse (a measure of the efficiency) achievable with cryogenic propellants (liquid Hydrogen and liquid Oxygen) is much higher compared to earth storable liquid and solid propellants, giving it a substantial payload advantage.
• Oxygen liquifies at -183 deg C and Hydrogen at -253 deg C. The propellants, at these low temperatures are to be pumped using turbo pumps running at around 40,000 rpm. It also entails complex ground support systems like propellant storage and filling systems, cryo engine and stage test facilities, transportation and handling of cryo fluids and related safety aspects.
• ISRO's Cryogenic Upper Stage Project (CUSP) envisaged the design and development of the indigenous Cryogenic Upper Stage to replace the stage procured from Russia and used in GSLV flights. The main engine and two smaller steering engines of CUS together develop a nominal thrust of 73.55 kN in vacuum. During the flight, CUS fires for a nominal duration of 720 seconds.
• Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) from the respective tanks are fed by individual booster pumps to the main turbopump to ensure a high flow rate of propellants into the combustion chamber. Thrust control and mixture ratio control are achieved by two independent regulators. Two gimballed steering engines provide for control of the stage during its thrusting phase

Analysis:

• The country started on the GSLV rocket plan in the late 1980s and early 1990s so as to be able to put its 2,000-kg communication satellites to geosynchronous orbits at 36,000 km in space from its own soil. It suffered a setback from geopolitics combined with high-technology commerce: Russia, at the behest of the USA, went back on a deal to transfer critical cryogenic technology for the last and crucial stage of the rocket. Starting in the mid-1990s, ISRO has developed its own cryo engine and has tested it on three vehicles since 2010.
• It was the first success of an operational GLSV flight with indigenous Cryogenic Upper Stage (CUS) engine. The INSAT-3DR is also the heaviest satellite that it has so far launched from the home soil.
• India has six meteorological satellites out of which three -- Kalpana-1, INSAT-3D and INSAT-3DR -- are exclusively for providing weather services.
• ISRO had faced several challenges during the development of the engine. Cryogenic engines were basically essential to put satellites in geostationary orbit, but the technology was quite sophisticated. The main reasons was - burning a super-cooled fuel at extremely high temperatures. ISRO was faced with the task of developing a material that can withstand the high temperature and pressure during combustion

By: Vishal