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GSLV F 01 launches Edusat successfullynews
21 September 2004

The sound of four strap-on booster rockets powered by 40-ton hypergolic liquid propellants (UH25 and N204) and the 138 tons of solid propellant in the core motor that provided a 4,736 kilo Newton (kN) thrust, reverberated throughout the Satish Dhawan Space Centre (SDSC), Sriharikota like a thunder roll.

As it started its ascent-first and final- thrust upwards at a power of 4,736 kilo Newton (kN) by the four strap-on booster rockets guzzling 40-ton of hypergolic liquid propellants (UH25 and N204) and 138 tons of solid propellant in the core motor, GSLV F 01's roar reverberated throughout the Satish Dhawan Space Centre (SDSC), Sriharikota.

As a flaming witness to the jubilant cheering by the Indian Space Research Organisation (ISRO) officials and journalists on the terrace of SDSC and of the people perched on nearby rooftops, the 49-metre high vehicle (weighing 414 tons) rose majestically to escape the earth's gravitational pull, leaving behind an anaconda like trail of white smoke.

17 minutes into its journey towards the heavens, GSLV F 01 performed its birth karma. It spat out its Rs90 crore payload 5,000 km away from the launch pad somewhere over Indonesia into a geosynchronous transfer orbit (GTO) of 180 km perigree (nearest point to earth) and an apogee (farthest point to earth) of 35,985 km. The orbital inclination was 19.2 degree from the equator.

Fired at intervals by the onboard liquid apogee motors, the satellite will be manoeuvred to the 36,000km-high geostationary orbit to be collocated with Kalpana-1 / Metsat and Insat 3C satellites at 74 degree East longitude. The dry mass of the satellite, which is the weight excluding the onboard fuel, is 820kg.

"We have once again demonstrated our capability to do a total job with precision," declared G Madhavan Nair, chairman, ISRO about the Rs345-crore mission (launch vehicle Rs160 crore, satellite Rs90 crore and ground infrastructure Rs95 crore).

Interestingly, September 20 is no more a jinxed date for ISRO. It may be recalled that in 1993 the first developmental flight of Polar Satellite Launch Vehicle (PSLV) failed when it was launched on September 20. Eleven years later on the same day, India's new launch vehicle was operationalised with a successful launch.

Everything relating to the mission went on like a clock-like precision. After the first stage got burnt out (strap-on motors in 150 seconds and the core motor in 104 seconds). 288 seconds into the flight, the second stage consisting of 39-ton fuel thrust GSLV F 01 burnt itself out. After that the third stage - the cryogenic stage with 12.5-ton liquid oxygen and liquid hydrogen - took over burning for 999 seconds of the flight after attaining a velocity of 10.2 km per second.

The perfect launch will help the satellite to complete its life cycle without many hitches. It should be noted that slinging the satellite into a faulty orbit would have forced the usage of on-board motors to bring the payload to the planned orbital path. The additional fuel, in effect, would have cut down the satellite's effective life.

Soon after its injection into GTO, the two solar arrays of Edusat were automatically deployed. The satellite is monitored by the ground station of ISRO Telemetry, Tracking and Command network (ISTRAC) located in the Indonesian island, Biak. The master control facility at Hassan in Karnataka has taken control of the satellite for all its post-launch opertions.

Successive GSLVs have had improved payload capacity. The first GSLV (GSLV D1) that went up in April 2001 had a payload of 1,540 kg (GSAT1). In May 2003 the second test vehicle carried 1,825 kg (See: ) and this time it was 1,950 kg.

Edusat - the specialised satellite
Conceived in October 2002, Edusat is the first satellite built exclusively to serve the education sector (See: - more than song and dance) and the second satellite that has been launched by ISRO to cater to a specialised sector. The first one being the meteorological satellite Metsat, which was subsequently renamed Kalpana 1 and launched on September 12, 2002."

The Edusat is primarily intended to meet the demand for an interactive satellite-based distance education system for the country. According to ISRO, the satellite built around a standardised spacecraft bus called I-2K has several new technologies.

It has a multiple spot beam antenna with 1.2m reflector to direct precisely the spot beams of five Ku band transponders towards their intended regions of India. One more Ku band transponder provides a national beam.

Apart from these six Ku band transponders Edusat also carries six extended C-band transponders with national coverage beam to join the Insat communication satellite system that has more than 130 transponders in C-band, extended C-band and Ku-band providing a variety of telecommunication and television services. (See: and )

Busy days ahead
Compared to the busy 2003 when ISRO accounted for five per cent of the 79 global launches with four satellites (Insat 3A, GSAT 2, Insat 3E and Resourcesat 1), this year has been subdued. Edusat is the first and last launch of this year.

Dr P S Goel, member Space Commission and director, ISRO Satellite Centre says, "We will soon catch up with that figure with our other launches in this fiscal." According to officials 2005 will be a busy year as ISRO has lined up the launches of Insat 4A, Cartosat-1 with Hamsat as co passenger in PSLV. Following that would be Insat 4B in 2005-06. Insat 4C, carrying 12 high power Ku-band transponders, which can also provide direct to home and VSAT services, will be launched during 2006-07.

Another satellite, Insat 3D exclusively for meteorological services is under development. The satellite will carry a six-channel imager and 19-channel sounder - is under development.

Work is already on for Insat 4 series satellites. ISRO plans to have five to seven satellites and has worked out transponder configuration based on the demand projected by different users. By 2007, Insat system will have nearly 200 transponders in different frequency bands catering to demands upto 11 giga bits per second (Gbps).

Meanwhile, the state-of-the-art second launch pad has been established at SDSC and it is awaiting its commissioning. The new pad will help to increase the frequency of launches from SDSC and reduce the occupancy time for the integration and launch.

It is learnt that the next PSLV flight carrying Cartosat 1 will be launched from the new pad.

Edusat's communication payloads
Five lower Ku-band transponders for spot beam coverage with 55 dBW Edge of Coverage-Effective Isotropic Radiated Power (EOC-EIRP)
One lower Ku-band transponder for national coverage with 50 dBW EOC-EIRP
Six upper extended C-band transponders for national coverage with 37 dBW EOC-EIRP
One Ku-band beacon to help ground users for accurate antenna pointing and uplink power control

Edusat satellite features
Geostationary (74 deg longitude)
Lift off mass
1,950 kg
Dry mass
820 kg
2.400m X 1.650m X 1.1530m cuboid
10.9m long with solar panels deployed
Propulsion and control
440 Newton Liquid Apogee Motor with mono methyl hydrazine as fuel and MON-3 as oxidizer for orbit raising, 3 axis body stabilisied in orbit using earth sensors, momentum / reaction wheels, magnetic torguers and eight 10 Newton and eight 22 Newton bipropellant thrusters
Solar array provident 2040 W and two 24 Ampere-Hour nickel cadmium batteries
7 years

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GSLV F 01 launches Edusat successfully