Sriharikota: Isro achieved yet another milestone as the PSLV-C35 rocket successfully accomplished a complex mission placing eight satellites into two different orbits on Monday.
During the two and a quarter hour mission, the longest ever undertaken by Isro, the fourth stage of PSLV was reignited twice successfully.
The four-stage 320 tonne Polar Satellite Launch Vehicle blasted off from the first launch pad of Satish Dhawan Space Centre in Sriharikota at 9.12 am with eight satellites weighing about 675 kg. After 17 minutes of launch, the 371-kg weather satellite ScatSat-1 was injected into the Polar Sun Synchronous Orbit 724 km above the earth.
PSLV-C35 coasted for about an hour before its fourth stage was reignited and shut off. After another reignition, the rocket launched the 7 other satellites into the polar orbit of 669 km above the earth. Immediately after the launch, the solar panels and antennas of the ScatSat-1 satellite were deployed.
“It has been a landmark day for Isro. After the gap of two hours, we have manoeuvred and restarted the fourth stage to insert the satellites into two different orbits. The entire mission went off successfully,” Isro chairman A.S. Kiran Kumar said after speaking to scientists.
“We have proved that PSLV can undertake any complex mission. All the satellites are positioned very precisely into the orbits. It is a very complex and longest mission PSLV has ever undertaken,” said B. Jayakumar, director, PSLV-C35.
Restarting a rocket engine soon after it is shut off is critical technology. “Once a rocket engine is activated, then the heat generated is very high. The trick is to cool it down in space and to restart it at a short gap,” Isro scientists said. They disclosed that better thermal and power management was needed for this longest mission.
The Rs 120 crore worth ScatSat-1 will provide weather forecasting services to user communities through the generation of wind vector products for weather forecasting, cyclone detection and tracking.
“ScatSat-1 is going to play a vital role for the climate modelling of the entire globe. Many international organisations including Indian Meteorological Department were eagerly anticipating this launch,” Isro scientists said.
It is a continuity mission for Scatterometer payload carried by earlier Oceaansat-2 satellite. The mission life of this satellite is five years. Apart from ScatSat-1, Algeria’s ALSAT-1B, ALSAT-2B, ALSAT-1N satellites and USA’s Pathfinder-1, Canada’s NLS-19 satellite were also launched during the mission. Student satellites PRATHAM from IIT Bombay and PISAT from PES Univesity in Bengaluru also launched.
