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IAS Pre Exam 2013 Paper 1

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IAS Pre Exam 2013 Paper 2

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GSLV-D5 lifted off GSAT-14


The refurbished Geo-synchronous Satellite Launch Vehicle (GSLV-D5) lifted off successfully on January 5, 2014, from the second launch pad at Sriharikota and it will put the communication satellite GSAT-14 into orbit. The GSLV-D5 have an indigenous cryogenic engine in its third, uppermost stage.
The launch of GSLV-D5 scheduled on Aug 19, 2013 was called off  after a leak was detected in the fuel system of the liquid second stage in pre-launch pressurisation phase on the vehicle. The leak was blamed on the fuel tank made of aluminium alloy called Afnor 7020 which tended to develop cracks over a period of time. The GSAT-14 communication satellite, which was encapsulated in the heat shield, was preserved and tested periodically.
The Liquid Propulsion Systems Centre (LPSC), ISRO came up with a new second stage with its propellant tank made of aluminium alloy 2219. The four strap-on booster motors were refurbished. The rocket’s first stage, which uses solid propellants, has been replaced with a new one. The restored vehicle has new electronic components because the components in the four strap-on motors in the earlier vehicle had become wet from the fuel leak. The integration of the second stage of GSLV D5 has already been completed and integration of the cryogenic stage is planned.
GSAT-14
GSAT-14  satellite is based on the I-2K satellite bus that has been used for a number of ISRO satellites of the 2,000-Kilogram weight-class. It weighs 2,050kg at liftoff featuring the conventional I-2K bus section with two deployable solar arrays and batteries along with avionics and data handling equipment as well as a propulsion unit and navigation equipment. GSAT-14 is 2 by 2 by 3.6 meters in size featuring a 2-meter and a 2.2-meter shell shaped reflector antennas.
The satellite is equipped with a Liquid Apogee Motor.  It provides a thrust of 440 Newtons and uses Mixed Oxides of Nitrogen as fuel and Unsymmetrical Dimethylhydrazine as oxidizer. The engine operates and an mixture ratio (O/F) of 1.65 and has a nozzle ratio of 160.
The engine’s injector is a co-axial swirl element made of titanium while the thrust chamber is constructed of Columbium alloy that is radiatively cooled. The engine is certified for long firings of up to 3,000 seconds. The Propellants are stored in spherical tanks that are pressurized with Helium.
The satellite payload consists of six Ku-Band and six C-Band transponders that will provide coverage across India. Also, a Ka-Band payload is installed on the vehicle which will transmit signals at 20 and 30 GHz to study the use of Ka-Band for satellite communications with focus on cloud and rain effects on signals. In addition, the GSAT-14 satellite is outfitted with a number of technological experiments for evaluation including fiber optic gyros, an active pixel sun-sensor, round-type bolometers and field programmable gate array based earth sensors. New thermal control materials are used on the satellite for evaluation. 
GSAT-14 was stationed at 75 degrees East in Geostationary Orbit for telecasting and telecommunication purposes. Its mission life is 12 years. GSAT-14 is the twenty third geostationary communication satellite of India built by ISRO. Four of GSAT-14’s predecessors were launched by GSLV during 2001, 2003, 2004 and 2007 respectively. After its commissioning, GSAT-14 will join the group of India’s nine operational geostationary satellites.
The main objectives of GSAT-14 mission are:
-To augment the in-orbit capacity of Extended C and Ku-band transponders
- To provide a platform for new experiments
The cuboid shaped GSAT-14 has a lift-off mass of 1982 kg and the dry mass of the satellite is 851 kg. GSAT-14 structure is based on ISRO’s 2 ton class platform (I-2K satellite bus). The
two solar arrays (each with two panels) of GSAT-14 together generate about  600 W of power, while the light weight Lithium-Ion Batteries supply power during eclipse period.
 
Some of the new experiments being flown on GSAT-14 are:
- Fiber Optic Gyro
- Active Pixel Sun Sensor
- Ka band beacon propagation studies
- Thermal control coating experiments Close-up view of GSAT-14 in clean room Configuration Lift off Mass : 1982 kg Main Structure : I-2K. Overall size (m) : 2.0 x 2.0 x 3.6
Antennae One 2 m and one 2.2 m single shell shaped reflector Antennae (transmit and receive)
GSLV-D5
GSLV is a three-stage launch vehicle with solid, liquid and cryogenic stages. It is designed to inject 2 Ton class of communication satellites to Geosynchronous Transfer Orbit (GTO). The four liquid L40 strap-ons as well as the second stage of GSLV use storable liquid propellants.
GSLV-D5 vehicle is configured with its first and second stages similar to the ones flown during earlier GSLV missions. The third stage is the indigenous cryogenic stage. The metallic payload
fairing with a diameter of 3.4 metre is adopted for GSLV-D5. S-band telemetry and C-band
transponders enable GSLV-D5 performance monitoring, tracking, range safety / flight safety and Preliminary Orbit Determination (POD).
Design Improvements in GSLV-D5
Based on its performance during the earlier missions, end-to-end design of GSLV as well
as indigenous cryogenic stage systems have been re-examined. Design modifications are
implemented wherever required along with rigorous ground testing and improvements are
made with respect to the fabrication and quality control to enhance the reliability.
These include:
• Redesign of Lower Shroud which protects the cryogenic engine during atmospheric flight of
GSLV-D5
• Redesign of the wire tunnel of the cryo stage to withstand larger forces during flight
• Revised Aerodynamic characterisation of the entire launch vehicle
• Inclusion of Video Imaging System to monitor lower shroud movement during various phases of flight
• Improvements in the Cryogenic upper Stage:
→ Modified design of the Fuel Booster Turbo Pump (FBTP), taking care of the expansion and
contraction of the bearings and casing at cryogenic temperatures
→ Modification of Ignition Sequence to ensure the smooth, successful and sustained ignition for
Main Engine (ME), Steering Engine (SE) and Gas Generator (GG)
In addition, indigenisation of many critical systems including Liquid Hydrogen Propellant Acquistion System (to prevent the possibility of contamination), Polyimide pipelines and Liquid Oxygen & Liquid Hydrogen Level Sensors has been successfully accomplished.
In order to validate the design improvements, the following extensive qualification tests have been carried out on the engine at the Main Engine Test (MET) facility and the High Altitude Test (HAT) facility:
• Two acceptance tests for flight unit of FBTP
• High altitude tests to confirm the ignition sequence in flight under vacuum
• Cryogenic Main Engine (200 sec) and Steering Engine (100 sec) acceptance tests All the improvements have been thoroughly reviewed by expert committees including eminent national experts.
Indigenous cryogenic engine
The mission’s importance lies in the three-stage GSLV-D5 using an indigenous cryogenic engine as the third upper stage. This is the second time that a GSLV is using an indigenous cryogenic engine developed by ISRO’s Liquid Propulsion Systems Centre (LPSC) situated at Mahendragiri, near Nagercoil in Tamil Nadu. The first flight to use an India-made cryogenic stage failed in April 2010. This is the eighth GSLV flight. Of the earlier seven GSLV missions, six used cryogenic engines from Russia.
ISRO’s Cryogenic Upper Stage Project (CUSP)
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.
However, cryogenic stage is technically a very complex system compared to solid or earth-storable liquid propellant stages due to its use of propellants at extremely low temperatures and the associated thermal and structural problems.
Oxygen liquifies at –183 deg C and Hydrogen at –253 deg C. The propellants, at these low temperatures are to be pumpedusing 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 turbo pump 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
gimbaled steering engines provide for control of the stage during its thrusting phase         
 
GSAT 14:Saliant Features
Configuration: Lift off Mass - 1982 kg; Main Structure - I-2K;Overall size (m) : 2.0 x 2.0 x 3.6
Antennae: One 2 m and one 2.2 m single shell
shaped reflector: Antennae (transmit and receive)
Power: 2600 W
Attitude and Orbit Control System (AOCS): Momentum biased 3-axis stabilized Mode
Propulsion System: Bi propellant–Mono Methyl Hydrazineand Mixed Oxides of Nitrogen (MON-3)
Communication Payloads:  6 Extended C-Band transponders; 6 Ku-band transponders
2 Ka-band beacons
Mission life: 12 years
Orbital Location: 74 deg East longitude in geostationary orbit
GSLV-D5 Mission
Overall Height : 49.13 metre
Lift-off Mass : 414.75 Ton
Lift-off Thrust : 6773 kilo Newton
No. of Stages : 3
Perigee : 180 ± 5 km
Apogee : 35975 ± 675 km
Inclination : 19.3 ± 0.1 deg