GSAT 7 – India’s First Defence Satellite

With the launching of GSAT 7 on August 30, 2012 India gets its first dedicated defence satellite, getting into a subtle civil-defence partnership. It's a spacecraft dedicated to Indian Navy because of its space bound marine communications. The satellite soared for 34 minutes before getting into the Geosynchronous Transfer Orbit (GTO) of 249 km perigee, 35,929 km apogee as well as an inclination of 3.5 degree with regards to the equator (Perigee and Apogee are the distances of the satellite from the earth, across the GTO, with former being the nearest and also the latter being the farthest).

• Inside a five days period (Aug 31st to Sep 4th) the satellite had completed three orbit raising manoeuvres (manned from ISRO) which to set up simple words is the utilization of propulsion systems to change the orbit of the spacecraft. Ending this the satellite was finally injected right into a geosynchronous orbit 36,000 kms over the earth’s surface. The satellite will be positioned in its destination slot of 74 degree east longitude by Sept 14th 2013.
• The satellite premiered from Kourou spaceport in French Guiana while using French company Ariansespace’s Ariane 5 rocket launcher. (The organization was established in 1980 because the world’s first commercial launch services provider).
• Together with GSAT 7, the launcher also orbited another spacecraft EUTELSAT 25B/Es'hail.

Geosynchronous Transfer Orbit (GTO): is medium difficulty orbit used to reach the destined geosynchronous or geostationary orbit while using satellite’s engine. The latitudinal angle of the geosynchronous orbit is maintained with respect to the equator.

Bands based on the satellite: The satellite carries payloads operating in UHF, S, C and Ku bands.

A GSAT uses transponder i.e. a tool which helps in magnifying a frequency signal or changing a frequency from the earth and reflecting it well to any location on earth’s surface.
The microwave spectrum ranges from 1 giga hertz to 100 giga hertz with many common applications lying within 1-40 GHz (L, S, C, X, Ku, K, Ka Bands).
Services Offered: A range of services which would be delivered when the satellite becomes functional ranges from low bit rate voice/fax/data to high bit rate enhanced audio/video/data communication capabilities over vast marine areas and Indian terrestrial areas.

This could come as an aid in search and rescue operations, distress forewarning, weather forecasting, data relaying, etc.
India’s GSLV Programme: India continues to be developing its Geosynchronous Launch Vehicles by means of three generations with all the launches being conducted from Satish Dhawan Space Centre in Sriharikota:

1) GSLV Mark I - 1-2 tonne GSAT launching capacity had following launches under it:

MK I (a) : GSLV D1 didn't place GSAT 1 in GTO in April 2001
Mk I (a) : GSLV D2 placed GSAT2 in May 2003
Mk I(b): GSLV F01 placed GSAT 3 (EDUCAT) in September 2004
Mk I(b): GSLV F02 was unsuccessful in launching INSAT 4C in the year 2006
Mk I(b): GSLV F04 failed partially to produce INSAT-4CR in 2007
Mk I( c ) : GSLV D4 didn't launch GSAT 5P in Dec 2010.
2) GSLV Mark II - 2-3 tonne GSAT launching capacity had following launches under it:

GSLV D3 - It had been the first Indian rocket operated by indigenously built cryogenic engine. It was to place GSAT 4, a 2220 kg communication satellite in GTO in Apr 2010 however was not successful due to non-ignition from the cryogenic stage.
GSLV D5 - It was to put GSAT 14 into 74 degree east longitude to assist provisioning of a number of satellite based services viz. tele-education, telemedicine, etc however the launch was called off as a result of leakage in the second liquid stage throughout the pre-launch pressurisation phase. It has been rescheduled for Dec 2013.
3) GSLV Mark III - Heaviest and many powerful launch vehicle asia which can place 4-5 tonne or heavier satellites.

India’s Three Stage Cryogenic Engine: ISRO is yet to check successfully our indigenous three stage cryogenic engine that is a requisite for launch of heavy satellites for example GSAT 7. Our home grown GSLV is really a three stage vehicle that's 49 metre tall, with a lift-off weight of 414 tonne.

First stage includes S125 solid booster with four liquid (L40) strap-on motors i.e. solid fuel based.
Second stage (GS2) is liquid engine which supplies a better thrust.
Third stage (GS3) may be the cryogenic stage, which is more efficient when compared to liquid stage in PSLV and uses cryogenic fuel - liquid hydrogen at -253 degree Celsius which utilizes surrounding air to boil and expand like a gas to more than 1000 times its volume. It offers one and a half times extra thrust than solid and liquid propellant and also at the same time weighs 50% less thereby enhancing the payload capacity of the launch vehicle.
Initially, India was acquiring Cryogenic Engine from Russian Space Agency. But, Russia refused to own technology to India within the wake of pressure in the USA, fearing that India can use the technology to develop long-range missiles. ISRO has been developing fraxel treatments since 1993. Testing of cryogenic rocket engine in India has been carried out at Liquid Propulsion System Centre (LPSC) in Mahendragiri, Tamil Nadu underneath the banner Cryogenic Upper Stage Project (CUSP).

To date, only USA, European Space Agency, Russia, China and Japan happen to be successful at developing their very own cryogenic engine technologies. Hope is the fact that India would join their league soon. Indigenous technologies aside from providing an edge to India would also reduce our expenditures to some great deal. But unless there's two such successful test flights, the hopes are minimal too.