Another launch success

The Polar Satellite Launch Vehicle PSLV-C6 successfully injects two satellites, CARTOSAT and HAMSAT, into sun-synchronous orbits.

T.S. SUBRAMANIAN in Sriharikota

IT is 10-05 a.m. on May 5. Just 10 minutes to go for the lift-off of the Polar Satellite Launch Vehicle (PSLV-C6). The automatic launch sequence begins. There is no tension in the air. In fact, the engineers of the Indian Space Research Organisation (ISRO) seated in front of their computer consoles at the Mission Control Centre (MCC) of the spaceport at Sriharikota (Andhra Pradesh) are blas about the blast-off.

This calm atmosphere was broken only when the PSLV rose from the newly built Second Launch Pad at the Satish Dhawan Space Centre (SDSC) and raced into the sky, tracing a parabolic path of flames and smoke on a clear sky. Applause filled the room when 1,078 seconds after lift-off, the spacecraft's fourth stage injected CARTOSAT-1 precisely into the polar sun-synchronous orbit. Forty-two seconds later, there was more applause when HAMSAT, which was riding piggyback, was sent into orbit. The two satellites were injected into their orbits at a height of 627 km at a velocity of 7.5 km a second. While CARTOSAT-1 weighed 1,560 kg, HAMSAT weighed 43 kg.

This is the PSLV's eighth successful flight in a row and the ISRO's 11th launch success. The first PSLV flight on October 20, 1993, was a failure.

President A.P.J. Abdul Kalam, a rocket and missile technologist, who sat in a glass-partitioned cabin in the MCC as a special visitor, could not contain himself as the launch vehicle lifted off majestically. With an impish smile, he briskly walked into the MCC and warmly hugged ISRO Chairman G. Madhavan Nair.

Nostalgic about his own association with ISRO, he called the engineers and scientists his "old friends", and congratulated them on their "excellent performance".

Abdul Kalam was Project Director of SLV-3's first flight on August 10, 1979, and its second flight on July 18, 1980. While the first flight ended in failure, the second flight was "a fantastic success" which propelled India into the exclusive space club, into the company of the United States, the Soviet Union, France, the United Kingdom, Japan and China.

The President recalled: "I was on the other side" of the Block House (the mission control room then) on July 18, 1980. On that day, the SLV-3 put Rohini, weighing 40 kg, into a low-earth orbit. Today, 25 years later, the PSLV can put a four-tonne satellite into low-earth orbit or a 1,600 kg satellite into polar orbit."

If there was any tension and anxiety among the ISRO engineers, it was only because the new launch pad was being blooded for the first time. An entirely new concept obtained in the launch pad. The launch vehicle was integrated vertically in a massive permanent building called the Vehicle Assembly Building (VAB) and transported to the launch pad proper. After the four stages of the 44-metre-tall PSLV-C6 were stacked up and married up with CARTOSAT-1 and HAMSAT on a massive launch pedestal inside the VAB, the vehicle on the launch pedestal, with an electrically driven bogie, was wheeled on a rail track to the launch pad about a kilometre away.

N. Narayanamoorthy, Project Director, PSLV-C6, said there was much excitement and tension as the vehicle was moved to the launch tower on April 30. The PSLV-C6 was free-standing, it had no anchorage. So the "stability of the vehicle was important". Any braking would have toppled the launch vehicle. The wheeling of the vehicle was a "flawless operation", he said. The PSLV-C6, standing freely with a bogie underneath the launch pedestal, reportedly took three hours to roll down the 960-metre rail track and reach the launch pad. At the launch pad, the vehicle was mated with the umbilical tower.

Gales and thunderstorm struck the spindle-shaped Sriharikota island in the Bay of Bengal as the vehicle stood exposed to the elements for five days. Madhavan Nair said, "There is some sort of strange relationship between the PSLV and the weather... . For two days, there was a thunderstorm." (The flights of the Geo-Synchronous Satellite Launch Vehicle (GSLV) on September 20, 2004, and the PSLV-C5 on October 17, 2004, took place from the First Launch Pad in heavy rain.)

The team led by John Zachariah, Deputy Director, Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, which was in charge of the integration of the vehicle, had done a fine job. The PSLV-C6 was made lightning-proof. Four towers flanked the launch pad to arrest lightning. George Koshy, Vehicle Director, and Anand Prakash, Associate Mission Director, were proud that the PSLV-C6 had withstood the onslaught of weather for five days.

K. Narayana, Director, SDSC, said the cost of construction of the Second Launch Pad was Rs.400 crores. MECON, a Ranchi-based public sector organisation, constructed the launch pad on a turn-key basis.

About the launch, Dr. B.N. Suresh, Director, VSSC, said the take-off was precise. "What we predicted and what happened were so close." The take-off and the perfect jettisoning of the stages was a well-choreographed sequence. R. Guruprasad, ISRO Public Relations Officer, said it was the clearest separation the ISRO had seen.

The PSLV traced "a fantastically accurate trajectory" as all the stage motors erupted into life on time and the stages jettisoned on time, Madhavan Nair pointed out. The vehicle's navigation system, which keeps the vehicle on path and guides the satellites into orbit, performed extremely well.

Dr. P.S. Goel, Director, ISRO Satellite Centre, Bangalore, described CARTOSAT-1 as "a unique satellite having simultaneous stereo-imaging capability." It is a satellite for cartography. Its imageries can be used for making accurate maps, which can be used in rural and urban development, in planning towns and in deciding the routes of new roads and canals. The satellite has two state-of-the-art cameras, which have stereo-imaging capability. That is, the two cameras will look at an object from two different angles. This will reveal the height of the buildings, slopes and hills. Dr. Goel said: "We believe that this cartographic mission with digital elevation modelling is a unique gift of India to the world." The imageries have a resolution of 2.5 metres. The entire world can be mapped with the help of CARTOSAT-1 in a year's time. "Whatever limitations we had in mapping so far will be addressed by this satellite," he said.

According to D.V.A. Raghava Murthy, Project Director, CARTOSAT-1, the satellite was tested for 21 days in the space simulation chamber at the ISRO Satellite Centre. It also underwent vibration tests on a shake-table. The two cameras, which were switched on around 10-45 a.m. on May 7, have started sending imageries. The first imageries received were taken over Punjab and Gujarat on May 8, and these were received at the Data Reception Centre of the National Remote-Sensing Agency in Hyderabad.

ISRO built HAMSAT as a contribution to international amateur radio operators (HAMs). It has two transponders. While a Dutch engineering student, who is a HAM, fabricated one, ISRO built the other. J.P. Gupta, Project Director, HAMSAT, called it a low-cost, easily operable satellite. Any HAM can make use of it. HAMSAT meets the long-felt need of HAMs in the South-Asian region to operate in ultra-high frequency and very high frequency mode.

Gupta said HAMSAT would provide an alternative means of communication (in organising rescue and relief measures) when blackouts and communication failure occurred. HAMs from all over the world have already started chatting with each other using HAMSAT and have complimented ISRO on the clarity of the signals they received.

While CARTOSAT cost Rs.250 crores to build, Rs.3 crores was spent on HAMSAT. The PSLV-C6 cost Rs.75 crores.