keeping better watch on seas, cyclones

Just past its 16th birthday and on its 16th mission, India's Polar Satellite Launch Vehicle (PSLV) placed with
characteristic perfection the country's 16th remote sensing satellite in a pre-designated orbit of 728 km.

It was the 15th consecutive successful mission for the 44-metre, 230-tonne launch vehicle, designated C-14 for this mission, ever since it failed on its debut on September 20, 1993.

"The PSLV is like old wine, it's improving with age,'' said ISRO chairman G Madhavan Nair after what he said was an excellent and precise launch. Oceansat-2, the country's second ocean studies satellite that aims to aid fishermen in identifying fishing zones and weathermen to forecast cyclones by measuring sea surface winds, was injected in a 728-km orbit, exactly 1,081 seconds after lift-off at 11.51 am.

For those who watched the clear skies above the spaceport in the Satish Dhawan Space Centre, but for a few innocuous cloudy patches, there would have been little indication of the initial glitches. During the 51-hour countdown (which began on Monday), scientists discovered an anomaly in the reaction control package. "We replaced it immediately. Normally, it would have taken a week, but we didn't want to lose even a minute,'' Nair said later.

Ultimately, it was a familiar sight, one witnessed many times before, as the PSLV zoomed into space over the island's skyline. The cheers from the assembled crowd erupted much before the sonic boom rolled towards them, as the rocket, tailed by a golden flame, remained visible for nearly a minute.

The separation of each stage and the ignition of the subsequent one occurred at almost precisely planned moments. Three minutes after lift-off, the heat shield separated at an altitude of about 125 km as the rocket cleared the dense atmosphere. The 18-minute flight was uneventful, as the 960-kg main payload, along with six tiny satellites made for educational purposes by various universities reached its orbit. Vice-president Hamid Ansari, who was present to watch the launch from the control room, and Prime Minister Manmohan Singh, congratulated the ISRO scientists for the successful mission.

The two solar panels of Oceansat-2, which will provide the required power for the satellite to operate, were deployed automatically soon after the orbital injection, and scientists confirmed that a ground station in Troll, Antarctica, had seen the satellites' activity from the polar region. The earth sensors had been turned on to orient it towards the earth.

With the launch vehicle costing Rs 160 crore and the main payload Rs 75 crore, it was described as a cost-effective mission by the ISRO chairman. "The polar satellite launch vehicle, considered ISRO's workhorse, can be compared to proven launchers like Ariane of France and Delta of US,'' he said. "It's of a similar class,'' he said, when asked to compare the PSLV with launch vehicles abroad known for their unfailing missions. Delta and Soyuz were also equally reliable, and PSLV was in their league, he added.

Oceansat-2, which will ensure continuity in services provided by its predecessor Oceansat-1 since 1999, has the potential to considerably enhance these services, thanks to its three payloads, said R R Navalgund, director of the Space Applications Centre, Ahmedabad. It will provide data on plant life in the ocean and changes in the oceans colour. The Ocean Colour Monitor (OCM), one of the payloads, will help in identifying schools of fish, their location, distance and depth from a particular spot, in monitoring algal blooms a sudden increase in the population of algae in marine environments that are potentially toxic and harmful to fish and in studying carbon-dioxide concentration in the ocean, Navalgund said.

The scatterometer on board will measure sea surface winds and provide data that can be used to understand the formation of cyclones. The data will be available to international scientists and can be used in real time for better prognostication, he said. The third payload, ROSA (Radio Occultation Sounder for Atmospheric Studies) will receive GPS signals and aid in developing profiles of atmospheric parameters like temperature, humidity, density and pressure).

Christened Cubesats, four of the six nano-satellites launched by PSLV-C14 are educational satellites developed by European universities two from Germany and one each from Turkey and Switzerland to test new technologies. The four cubesats, each weighing only about one kg, were released for operations, while Rubin 9.1 and Rubin 9.2 will remain attached to the upper stage. These nano-satellites are meant for maritime applications and weigh eight kg each.