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Devangshu Datta: PSLV-C6: A path-breaking launch


Devangshu Datta  |  New Delhi 

The Encyclopaedia Astronautica's entry on the Indian polar satellite-launch vehicle (PSLV) programme says that eight of the nine launches have been successful. The first launch, back in 1993, failed due to a software glitch.
The PSLV-C6 launch on May 5 was the first take-off from the newly commissioned second launchpad at the Satish Dhawan Space Centre, Sriharikota. It established several milestones. Most critically, it proved the new launchpad met the specifications laid down by the boffins of (Indian Space Research Organisation).
The PSLV-C6 carried two satellites, which were placed into polar sun-synchronous orbits. Hamsat relays global amateur radio operator (ham) signals.
Cartosat-1 carries high-resolution cameras for earth-imaging. The launch has brought India's space programme one critical step closer to fulfilment of the Rs 380-crore Chandrayan project, which targets the moon in 2007-2008 through the use of modified PSLVs.
It cost Rs 400 crore to build the new launch facility "" not much in a context when the "flyaway" cost of each launch is estimated at Rs 70 crore. The first pad remains operational and two facilities offer more flexibility.
ISRO's design specifications were translated into structures on the ground by MECON, on a turnkey basis with contributions from some 140 sub-contractors.
The second complex contains a vehicle assembly building (VAB) for multi-stage vehicles such as the 300-tonne or the 420-tonne Geo-Synchronous Satellite Launch Vehicle (GSLV) or the futuristic 630-tonne GSLV- Mk-III; or even a 1,000-tonne rocket.
The integrated architecture is a new paradigm "" other space agencies use different VABs for different designs.
The VAB is 82 metres tall by 40 metres into 32 metres "" the same dimensions as a 30-storey skyscraper. Since Sriharikota is on a Bay of Bengal beach, the VAB is over-engineered to withstand cyclones.
The mechanised building has cranes and platforms placed at various heights for ease in the assembly of multi-stage vehicles. Rockets assembled in the VAB are placed on a 16-wheel mobile launch pedestal on a specially built rail-track.
The launcher moves to the launchpad, about 1 km from the VAB. The pad itself is made from reinforced concrete with angled tunnels to deflect the flames at blast-off.
PSLV-C6 lifted off at 10.14 IST on May5. It placed two satellites into orbit, 620 kms above the earth, about 18 minutes later. The 1,560 kg Cartosat-1 carries two mobile, "panning" cameras capable of 2.5 metres per pixel resolution.
The mobility offers stereo imaging at levels precise enough to map every house. This has killer applications in agriculture, water-management, digital map-making and municipal tax assessment.
Cartosat-1 is the first civilian earth-imaging effort of such precision and Antrix Corporation, ISRO's marketing arm, hopes to sell its data in the global markets.
Cartosat-2 is planned for launch in 2006 with one-metre resolution. A radar imaging satellite is also in development for 2007.
Cartosat-1 data is received at the National Remote-Sensing Agency (NRSA), Hyderabad, which resolves the images. The Telemetry, Tracking and Command Network at Bangalore controls the cameras.
The first images (of Punjab including urban Amritsar and Gujarat) are available. Cartosat is powered by solar panels. The 43-kg Hamsat contains transponders built by amateurs to relay radio signals from ham operators.
After decades of discouraging hams by prohibiting operations in "sensitive" areas and much red tape, the government has recognised their utility in disaster management. After the Orissa supercyclone and in the islands post-tsunami, hams did a great job re-establishing communications.
ISRO put up Hamsat in an acknowledgement of its gratitude to the global ham community "" it will be operational for two years. Hamsat has received rave reviews from the ham network and clear audio conversations transmitted through Hamsat are available.
INSAT-4A will be launched in July-August from French Guyana. Another PSLV launch is scheduled for March 2006, which is when Cartosat -2 will be positioned if all goes well. The Astrosat (for star-imaging) is due in 2007 and ISRO will host the launch of the Italian Agile.
Chandrayan seems to be proceeding on schedule to the rendezvous with Luna.

First Published: Thu, May 12 2005. 00:00 IST