PSLV-C21 Creates Historic Landmark: ISRO Making 100th Mission Grand Success

An Indian Space Research Organisation (ISRO) rocket has successfully put into orbit two foreign satellites, making the space agency’s 100th mission a grand success. The Indian space agency celebrated its 100th mission with a flawless launch of the Polar Satellite Launch Vehicle (PSLV) from Sriharikota. Given the long association between the French and Indian space programs, it was particularly appropriate that this landmark launch carried France’s SPOT 6 satellite.

This PSLV launch vehicle which has been putting our satellites around the Earth’s orbit has stupendously moved towards the Moon target through ‘Chandrayaan’ mission. It is the same PSLV that will make India and the ISRO embark on journey to Mars.

Spot-6 Launch

ISRO’s workhorse PSLV placed in orbit France’s Spot-6 satellite and the Japanese craft Proiteres some 18 minutes after a perfect liftoff from the Satish Dhawan Space Centre, completing its 100th successful launch.

Spot-6 is an earth observation satellite, while Proiteres is intended to observe Japan’s Kansai district through a high-resolution camera.

The 44-metre PSLV took off on its 22nd flight into the overcast skies carrying the French satellite with a liftoff mass of 712 kg, the heaviest to be launched by India for an international client, and the 15-kg Japanese micro-spacecraft.

At the end of a 51-hour countdown that started on September 7, PSLV-C21 lifted off at 9.53am. After 17 minutes and 49 seconds, it injected the first satellite, France's SPOT-6, into orbit. Seconds later it put the Japan's Proiteres in orbit. The launch was scheduled at 9.51am but was delayed by two minutes after India's Inertial Navigation System, which guides rockets and helps them put satellites in orbits with pinpoint precision, relayed an alert of a possible collision with space debris.

After a perfect launch, as the rocket roared into space, there was a minor scare. Scientists watched anxiously as the trajectory of the rocket on giant screens at the mission control room showed it deviate slightly mid-flight. But its course was soon corrected and it followed the flight plan flawlessly before inserting its payload into orbit.

SPOT 6 is the heaviest foreign satellite to be carried by a PSLV since 1999 when ISRO started launching satellites of foreign agencies. Proiteres will study the powered flight of a small satellite by an electric thruster and observe Japan's Kansai district with a high-resolution camera.

On the two-minute delay in the rocket’s lift-off, ISRO Chairman K Radhakrishnan said it was to avoid possible collision with space debris. He said ISRO would set up a Multi-Object Tracking Radar (MOTR) to track space debris and time its rocket launches accordingly.

Undoubtedly, the GSLV is an immensely more complicated launch vehicle the cryogenic engines of which are very difficult to master. India has been using Russian cryogenic engines, but our own effort to develop such engines has not fared well and the last GSLV launch failed because the Indian-built cryogenic engine did not perform successfully. As of now, India is dependent on foreign space agencies to put its heavy satellites into geo-stationary orbits.

Success Story

ISRO began its space program in 1975 with the launch of its first satellite Aryabhata. With the present launch, ISRO completed its 100th successful mission. It has so far launched 62 Indian and 29 foreign satellites from Sriharikota and foreign launch pads.

It has so far injected 28 foreign satellites into orbit, beginning with Germany’s 45-kg DLR-TUBSAT aboard the PSLV-C2 in 1999. SPOT-6 is the PSLV’s biggest commercial lift so far. The financial matters relating to the launch could not be disclosed, but the cost of the vehicle was recovered. The ISRO also sent its own payload, ‘Mini Resins,’ for demonstration of an instrument called Redundant Strap down Inertial Navigation System.

Trouble-Prone GSLV

With the PSLV, the country does not have to look abroad for launching its remote sensing satellites. But the same is not true with communication satellites. In contrast to the PSLV, the trouble-prone Geosynchronous Satellite Launch Vehicle (GSLV) has been hampered by delays in mastering the cryogenic technology required for it as well as other problems. Moreover, ISRO’s needs appear to go beyond the capabilities of this rocket, which was designed to carry two-ton communication satellites.

The PSLV has become a rugged workhorse with 21 consecutive successful launches behind it. It has taken over 50 satellites and spacecraft into space, half of them for foreign customers. Since it became operational, the PSLV has carried all of India’s remote sensing satellites and also launched the country’s first lunar probe, Chandrayaan-1.

India is set to put a spacecraft in the orbit of Mars to study its atmosphere and the launch will be done in November next year from Sriharikota in Andhra Pradesh with the help of PSLV.

The organization already has its sights set on its next assignment, the Mars Orbiter Mission on August 3, 2012 for its proposed launch in 2013, after receiving approval from the Union Cabinet.

To conclude, it can be said that ISRO has done the nation proud with its success in mastering space technology. India is on the threshold of achieving greater success in space, both in satellite technology as well as satellite delivery systems.

India's GSLV-D3 Rocket Launch Fails

India's Geosynchronous Satellite Launch Vehicle (GSLV-D3 -- built with Rs. 330 crore ($74.4 million) mission (rocket Rs. 180 crore, GSAT-4 satellite Rs.150 crore) -- failed on 15 April because two small cryogenic engines apparently failed to ignite within minutes of its launch, leading it to deviate from its path. The GSLV-D3 was launched using an Indian-designed and built cryogenic engine for the first time.

The rocket lifted from the Indian Space Research Organization's (ISRO) Satish Dhawan Space Centre (SDSC) launch pad in Sriharikota at 1057 GMT. However, the launch was not perfect with the GSLV-D3 failing to send any data after 500 seconds of taking off. The rocket deviated from its path and the scientists monitoring the launch said that they did not receive any speed and altitude data from the vehicle.

Cause of Failure
ISRO Chairman K. Radhakrishnan said: 'The vehicle was tumbling. The control was lost as two small cryo engines did not ignite.'

The GSLV-D3 was to put the 2.2-tonne communication satellite GSAT-4 into the Geo Transfer Orbit (GTO) on 15 April evening. Until now ISRO had been using Russian cryogenic engines in its GSLV missions as the United States had forced Moscow not to sell the cryogenic technology to India in 1992.

Previous GSLV Flights
The previous five GSLV flights from Sriharikota from 2001 to 2007 used the Russian cryogenic engines. The GSLV-D3 vehicle is 49 meters tall and weighs 419 tones. It is a three-stage rocket. The core first stage is powered by solid propellants. Around this core stage are four strap-on motors powered by liquid propellants. The second stage again uses liquid propellants. The third upper stage is propelled by the indigenously made cryogenic engine. Filling of the second stage and the four strap-on booster motors with liquid propellants will be completed during the countdown.

In addition, the filling of the cryogenic engine with liquid hydrogen and liquid oxygen will continue till almost the end of the countdown. This is to prevent loss of cryogenic fluids due to evaporation. Certain mandatory checks of the vehicle and charging of the batteries in both the rocket and the satellite would be done during the countdown.

The GSAT-4 weighs 2,220 kg. It carries a communication payload called Ka-band transponder for wide-band multimedia services, e-commerce and high bandwidth Internet. The navigation payload named the GPS-aided Geo-Augmented Navigation (GAGAN) system will help commercial aircraft to land accurately in runways during inclement weather.

Salient Features
The cryogenic stage was built at the Liquid Propulsion Systems Centre (LPSC), Mahendragiri, Tamil Nadu. Cryogenic engines are crucial for putting communication satellites weighing more than two tones into a GTO. Cryogenic technology involves the use of liquid oxygen at minus 183 degrees Celsius and liquid hydrogen at minus 253 degrees Celsius.

Mohammed Muslim, Project Director, Cryogenic Upper Stage Project (CUSP), said the cryogenic technology was the most complex one to be developed by the ISRO. It has taken us 15 years to achieve this. It is normal time for any country and we are the sixth country to acquire this technology (after the United States Russia, Europe, Japan, and China). This is a highly guarded technology. The ISRO had not taken chances with this mission and "the vehicle has been reviewed and checked point by point any number of times.

The ISRO built the cryogenic engine from scratch after the U.S. pressured Russia in April 1992 and July 1993 into agreeing not to sell cryogenic technology to India. In January 1991, India and the erstwhile Soviet Union had reached an agreement, under which the Soviet space agency, Glavkosmos, would sell cryogenic stages and transfer the cryogenic technology to India.

US Pressure Pays
Under the US pressure, Russia in July 1993 went back on its agreement to transfer the cryogenic technology. In lieu of the technology, it agreed to sell two additional cryogenic stages to India. The last five flights of the GSLV from Sriharikota were powered by the Russian cryogenic stages. A cryogenic stage includes the engine, propellant tanks, motor casing and wiring.

In fact, it took the ISRO all these years to develop the cryogenic technology because it had to develop special materials. At very low temperatures of liquid hydrogen and liquid oxygen, metals become brittle. The ISRO, therefore, had to develop new alloys, new welding techniques and new types of lubricants.