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Improved GSLV D2 to take off from Sriharikota on 8 Maynews
Venkatachari Jagannathan
07 May 2003

Chennai: The second development geosynchronous satellite launch vehicle (GSLV D2) is all set to roar up on 8 May 2003 from Satish Dhawan Space Centre, Sriharikota.

The launch vehicle will carry GSAT-2 weighing 1,800 kg to place it in a geosynchronous transfer orbit (GTO) of 180 km perigee (nearest point to earth) and 36,000 km apogee (farthest point to earth).

Indian Space Research Organisation (ISRO) ventured into GSLV project to acquire launch capability for geosynchronous satellites. The first test launch was made on 18 April 2001 when it placed the experimental satellite GSAT-1 in a geosynchronous transfer orbit (GTO) (See '').

With the 49-metre-long GSLV D2, India moves one step forward towards enhancing its commercial exploitation of satellite launch capabilities. What is interesting is that there are quite a few differences between GSLV D2 that is going up on 8 May 2003 and the one that went up two years ago.

First the speed, GSLV D2 will deliver its payload faster than its predecessor. As per plans the launch vehicle will sling its payload GSAT 2 997 seconds after the lift-off. GSLV D1 did that after 1,040 seconds after the lift-off. For instance, the payload GSLV D2 will carry GSAT2 weighing 1,800 kg. On the other hand the first test flight placed GSAT1 weighing 1,540 kg.

According to ISRO, the higher payload in GSLV D2 has been achieved by incorporating:
1. Enhanced propellant loading in core solid motor
2. High-pressure engines in liquid propellant strap on motors in the first stage and also in the second stage. (GSLV D2 is a three-stage launch vehicle. The first stage, apart from the engine in the main vehicle, also has four motors strapped to give additional power.)
3. Optimisation of structural elements.

Similarly GSLV D2 will be weighing 414 tonnes as against its elder version that weighed 13 tonnes less. While GSLV D2 will be carrying little more fuel in all the three stages (the four S139 strap on motors in the first stage carries more fuel), interestingly the burn time is less. For instance, each of the four strap on motors will carry 42-tonne fuel and will burn for 149 seconds while GSLV D1's S125 strap on motors carried 40-tonne fuel that burnt for 160 seconds.

Similar is the case with the rocket's second and third stages. Differences are also there in the payload carried by the two launch vehicles (See the comparison table). GSLV as a launch vehicle will be declared operational if the second test flight is successful.

Comparison table

 
GSLV D2
GSLV D1
Height
49m
49m
Weight
414 t
401 t
No.of stages
3
3
Payload
1800kg
1540kg
 
 
 
I Stage
 
 
 
 
 
Length
20.1 m
20.3
Fuel- Solid Propellant motor
S139
S125
Fuel
Hydroxyl Terminated
Poly Butadiene (HTPB)
Fuel weight
138t
129t
Burn time
107 seconds
100 seconds
Thrust power (in kilo Newton)
4,736
4,700
4 propellant strap
on motors
L40H
L40H
Length
19.70m
19.70m
Fuel capacity each
42t
40t
Burn time
149 seconds
160 seconds
Thrust power
(in kilo Newton )
765
680
 
 
 
II Stage
 
 
 
 
 
Length
11.6m
11.6m
Fuel capacity
39.3 t
37.5t
Burn time
136 seconds
150 seconds
Thrust power
(in kilo Newton)
804
720
 
 
 
III Stage
 
 
 
 
 
Cryogenic Stage
 
 
Length
8.7 m
8.7m
Fuel
Liquid hydrogen
liquid oxygen
Capacity
12.6 t
12.5t
Burn time
705 seconds
705 seconds
Thrust power
(in kilo Newton)
73.5
75
Injection time
of satellite
from lift off
997 seconds
1,040 seconds

GSAT

  GSAT2 GSAT1
Weight 1800kg 1540kg
Transponders
C Band
4nos 2nos
Ku Band 2 nil
Fuel capacity 840kg NA


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Improved GSLV D2 to take off from Sriharikota on 8 May