ISRO launches nano satellites from Sriharikota

Sept. 23, 2009 - PRLog -- The launch was carried out as per schedule at 11.51 am and ended at 12.06 pm.

The 44.4-metre tall, 230-tonne Indian rocket Polar Satellite Launch Vehicle (PSLV) freed itself from the launch pad at the spaceport and lifted itself up, lugging the 960-kg Oceansat-2 and the six nano satellites all together weighing 20 kg.

In copybook style, the rocket first flung out Oceansat-2 at an altitude of 720 km above the earth in a sun-synchronous orbit (SSO), followed by the four nano satellites - also called Cubesats, each weighing one kg. The remaining two, each weighing eight kg, were attached to the rocket's fourth stage.

Of the six nano satellites, four are from Germany, one is from Switzerland and one from Turkey. The seventh is a big one, India's Oceansat-2 weighing 960 kg.

Soon after the satellites were put into orbit, Indian Space Research Organisation's (ISRO) satellite tracking centres started monitoring them.

Vice-President Hamid Ansari who was present at the Satish Dhavan Space Centre SHAR, congratulated the scientists and technocrats over this splendid achievement for the nation.

Seven satellites in 1,200 seconds. The launch is similar to the one in April 2008 when ISRO launched 10 satellites.

The sequence of ejection is very similar to the April 2008 launch featuring one big satellite - Cartosat-2A and nine other nano satellites - 10 in all: once the PSLV takes off and reaches a certain height and velocity, it will first launch the Oceansat-2 and a few seconds later, the first of four nano satellites. Every 10-12 seconds, the PSLV will launch four satellites one after the other. (Two will remain with the fourth stage).

"The rocket re-orients itself everytime a satellite is to be placed in orbit. The re-orientation ensures one satellite doesn't collide with another. The rocket effectively re-orients itself four to five times in the space of one flight," a scientist explained.

The brain of the rocket would have made all calculations in advance - from ejection of first satellite to the fifth. The exact moment of ejection and then re-orientation for the next ejection is worked out in advance. All mathematical calculations on the ground, launch sequence and flight path have to work to zero error.

"There is no room for error. The rocket has to be in flight till the last minute which means all systems on board have to function to perfection. Once the first and second stages separate, and the fourth stage (the engines) stop, the ejection process begins until every satellite circulates in orbit," an official said.

Oceansat-2, India's second satellite to study oceans as well as interaction of oceans and atmosphere, is the 16th remote sensing satellite of India. It is in the shape of a cuboid with two solar panels projecting from its sides. The satellite will map fishing zones around India, measure ocean surface windspeeds as well as atmospheric temperature and humidity.

This will be PSLV's 16th mission. From September 1993 to April 2009, PSLV has been launched 15 times. Fourteen launches have been successful continuously while only one has failed so far.

ISRO spokesperson S Satish told TOI: "It is known that PSLV has been a very successful launch vehicle. Countries realise it is a vehicle or rocket very well suited for launch of nano satellites. We were on to our 16th mission with PSLV and Germany and Swtizerland were looking for a mission. Our needs coincided and that's how we have the six nano satellites."

In the April 2008 launch, eight nano satellites were built by universities and research institutions in Canada and Germany.
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