The Indian space odyssey crossed a milestone on Sunday, as the fully-indigenous Polar Satellite Launch Vehicle (PSLV-C21) blasted off from the Satish Dhawan Space Centre (SDSC) here, 100 km north of Chennai, and precisely injected two foreign satellites into their near-planned orbits to make the 100th Indian space mission a grand success.

Despite a two-minute delay in the take-off of the PSLV's 22nd flight from the first launch pad here, zooming into a balmy sky at 9:53am against the initial window of 9:51am, the Indian Space Research Organisation (ISRO)'s workhorse yet again proved its mettle.

Spewing black fumes as it roared into the sky, the 44 metre tall, 230-tonne heavy PSLV-C21 performed well in all the four stages of its pre-determined trajectory and first injected "Spot-6," the latest generation earth imaging remote sensing satellite built by France, into a Polar orbit after about 18 minutes. The rocket then ejected a 15-kg Japanese micro-satellite "Proiteres," to the delight of the space scientists at the SDSC.

"The PSLV-C21 has done its work and India deserves it,'' said the ISRO official at the media centre here, as Prime Minister Manmohan Singh who was accompanied by V Narayanasamy, MoS in the PMO, and a battery of space scientists and officials witnessed the launch from the New Mission Control Centre. Later, the prime minister congratulated ISRO chairman K Radhakrishnan and his team on the feat and announced to the nation of ISRO's 100th Space Mission being a "spectacular success, a milestone in our nation's space capabilities".

Mission Director P Kunnikrishnan, addressing a news conference later with the ISRO chief and other top scientists, said the PSLV-C21 had "precisely injected'' the two satellites. The orbit "was very precise and very consistent" and all stages performed exceedingly well. The health of the two satellites "is normal.'' To their great relief, the solar panels had also been deployed, marking the successful culmination of the mission from ISRO's point of view.

Radhakrishnan said ISRO had committed to the two foreign satellite builders to launch their satellites into a "655-km polar orbit inclined at an angle of 98.23 degree to the equator," with a dispersion of plus or minus 20 km from that committed figure. "But, we have been able to achieve a dispersion within a 7-km range vis-a-vis the orbit which proved the accuracy of our censors," the ISRO chairman told reporters.

Admitting that there was a two-minute delay in the PSLV-C21 lift-off on Sunday morning, Radhakrishnan said it was done after extensive consultations over the "impact of possible debris in space that could come in the way'' when the satellites were launched from Sriharikota. "We also had to look at possible collisions in space.''

While Radhakrishnan declined to discuss how much ISRO would be paid for the launch of these two foreign satellites due to the clause in the commercial agreement, he assured the media that cost of the mission had been recovered by this successful flight.

"We don't talk of net profit or loss'', he added. More importantly, this mission enabled testing of crucial technologies for ISRO as well, including its "new inertial navigation system and in bringing down the overall package mass by 50 kg," said Radhakrishnan.

The PSLV-C21, significantly, has been the eighth flight of the PSLV in its "core-alone configuration (without strap-on motors)." But in carrying the 712-kg "Spot-6" payload of France on Sunday, the PSLV launched its heaviest satellite yet for an international customer, emphasised the ISRO chief.