Satellite school

EDUSAT, India's first exclusive satellite for taking education to rural and remote areas, is expected to herald a revolution in distance and adult education in the country.

in Sriharikota

THERE was no tension in the Mission Control Centre at the Satish Dhawan Space Centre, Sriharikota, Andhra Pradesh, on September 20 afternoon. The Indian Space Research Organisation's (ISRO) top engineers and scientists sat relaxed, confidently looking at the computer consoles in front of them. As the plot-board on the monitors showed, the first operational flight of the Geo-synchronous Satellite Launch Vehicle (GSLV-FO1) was turning out to be a flawless mission after the vehicle's lift-off at 4.01 p.m. from the spaceport at Sriharikota. At the end of 17 minutes of flight, when the GSLV-FO1's third, upper cryogenic stage injected EDUSAT (Educational Satellite), built by ISRO Satellite Centre, into a perfect geo-synchronous transfer orbit, the Mission Control Room reverberated with applause.

It was the third straight success for the GSLV after the previous missions in April 2001 and May 2003. And it was the tenth success in a row for ISRO - the GSLV's hat-trick plus the Polar Satellite Launch Vehicle's (PSLV) seven consecutive successes.

The 1,950-kg EDUSAT is the heaviest satellite launched by ISRO. The first GSLV flight put in orbit GSAT-1, which weighed 1,540 kg, and the second orbited the 1,825 kg GSAT-2. Both were experimental communication satellites.

G. Madhavan Nair, ISRO Chairman, described the GSLV-FO1 flight as "one of the finest missions ISRO has had". There was no hold at all in the final count-down despite a heavy downpour and lightning. The entire launch operation sequence went as planned. "The entire trajectory was unbelievably good," he said. The vehicle's three stages ignited and cut off at the right time and altitude.

Dr. P.S. Goel, Director, ISRO Satellite Centre, Bangalore, described EDUSAT as "a complex spacecraft". It would become operational in a month's time after performing a series of critical operations. According to Goel, telemetry data showed that the satellite was in good health.

EDUSAT is India's first exclusive satellite for taking education to rural and remote areas. With its array of sophisticated transponders, it is set to herald a revolution in distance education in the country. It is configured to have different beams for the various regions of the country. An expert in a subject can simultaneously teach hundreds of students in various schools or colleges across a wide area. The teacher will operate from a television studio and students in schools and colleges with reception facilities can see the teacher and listen to him. In institutions that have interactive systems, students can put questions to the teacher and receive replies. If a candidate pursuing correspondence education has reception and interactive systems at home, EDUSAT will convert his/her home into a virtual classroom.

Adult literacy programmes will receive a boost through community reception/interactive systems in a village. Besides supporting formal education, EDUSAT will be a boon to the non-formal education stream. It can disseminate knowledge to the rural population on health, hygiene and innovative farm practices, and allow professionals and workers to update their knowledge.

Madhavan Nair said: "It is almost like video-conferencing. It is almost as if the professor is standing in front of us." But the challenge lies in identifying good teachers and the lessons to be generated and in using innovative techniques to explain geography, science, mathematics and so on.

Since EDUSAT has regional beams for the southern, northern, north-eastern, western and western regions of the country, teaching can be done in the languages of various States.

ISRO has signed memorandums of understanding (MoU) with several institutions for the use of EDUSAT's transponders. These include Visvesvaraya Technological University, Belgaum, Karnataka; the All-India Council of Technical Education; the Indian Institutes of Technology; Anna University, Chennai; Indira Gandhi National Open University; Y.B. Chavan Open University, Nashik, Maharashtra; and Rajiv Gandhi Technical University, Madhya Pradesh.

More than 100 colleges affiliated to the Visvesvaraya Technological University are already linked to INSAT-3B, and their students are simultaneously imparted tele-education. These colleges will switch over to EDUSAT after it becomes operational.

The concept of beaming educational programmes though satellites was demonstrated for the first time in the country in 1975-76. It was called Satellite Instructional Television Experiment (SITE), and Prof. E.V. Chitnis, then Director, Space Applications Centre, Ahmedabad, played a major role in it. SITE used the American Application Technology Satellite (ATS-6). Through SITE, programmes on health, education and hygiene were telecast directly to about 2,400 villages in six States. With the commissioning of INSAT system in 1983, a variety of educational programmes are being telecast.

THE GSLV is 49 metres tall, and weighs 414 tonnes. It had three stages. The core main stage was powered by solid propellants. Strung around it were four strap-on booster motors fuelled by liquid propellants. The second stage is energised by liquid propellants. Cryogenic fluids - liquid oxygen and liquid hydrogen - galvanise the third upper stage. Russia supplied the equipment necessary for the cryogenic stage. It injected the satellite into orbit with a velocity of 37,000 km an hour. The Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, built the vehicle.

While it cost Rs.160 crores to build the GSLV-FO1, ISRO spent another Rs.90 crores in fabricating EDUSAT. G. Ravindranath was Mission Director, N. Jayachandran Nair was Vehicle Director and N. Neelakantan, EDUSAT Project Director.

ISRO added a new feature to the mission this time by using an innovative technology called "day-of-the-launch wind scheme" to measure the upper atmospheric and lower atmospheric wind velocities (which play a crucial role on the load on the vehicle), and fine-tuned the flight trajectory, and launched the vehicle.

The launch took place against many odds. Madhavan Nair said: "The weather turned bad. There was a heavy downpour and lightning activity too. We virtually thought we had to postpone the launch." But using the radar system that ISRO had developed for monitoring the cloud conditions and the rainfall pattern, ISRO decided at 9.30 a.m. on the D-day to go ahead with the launch.

The upper atmospheric winds normally affect the performance of a launch vehicle. One of the missions of ISRO's Augmented Satellite Launch Vehicles (ASLV) failed because of atmospheric turbulence, and the consequence load it encountered due to winds and shear. "So we have constantly updated this technology [day-of-the-launch wind scheme]. Today, we have perfected it in such a way that we can measure the wind that is occurring on the day of the launch and fine-tune our trajectory so that the loads on the vehicle will be minimum," he said.

An ISRO launch vehicle technologist said that until this flight, ISRO would measure the mean wind velocity up to a certain time before lift-off. However, this time, using the radars ISRO had developed, it generated data about the winds in real time, fine-tuned the trajectory according to the data, and loaded it into the flight computer.

John P. Zachariah, Deputy Director, Vikram Sarabhai Space Centre (VSSC), said the GSLV-FO1 was a water-proof vehicle. It had been tested and qualified for flying in heavy rains. ISRO was prepared to launch it in the rains but the winds and lightning were severe, Zachariah said.

The bad weather delayed the roll-out of the 76-metre tall Mobile Service Tower (MST) in which the three-stages of the launch vehicle had been integrated vertically. The MST should have been wheeled out on its huge hydraulic wheels on a rail track at 1 a.m. on September 20. But it was rolled out at 9 a.m. About 30 minutes later, the decision to go ahead with the launch was taken. The final count-down proceeded without any hitch.

At the appointed time of 4.01 p.m. the four strap-on liquid motors fired, the core main stage fired 4.7 seconds later. The GSLV-FO1 rode on balls of orange flames into the sky. The three stages ignited and jettisoned at the appointed time. The navigation and control systems worked perfectly. Seventeen minutes after the lift-off, EDUSAT was injected into the geo-synchronous transfer orbit.

Said Ravindranath, Mission Director: "We have got the most perfect orbit of all the (19 including the present) launches from SHAR." The apogee was 35,985 km and perigee 180.54 km. It was an elliptical orbit as was intended. The Liquid Apogee Motor (LAM) was fired on three different days subsequently to circularise the orbit.

Dr. B. N. Suresh, Director, VSSC, said the success showed ISRO's maturity in complex launch vehicle technology. "We have not looked back after the PSLV's first failure in 1993. The GSLV is a robust vehicle," Suresh said. R.V. Perumal, Director (Projects), VSSC, said the third GSLV success demonstrated that the basic design of the vehicle was sound.