Engines in the fourth stage will be reignited three times

the countdown for the PSLV-C38 mission began on Thursday morning, engineers at ISRO were preparing to execute a series of complex manoeuvres for the shutdown and reignition of the rocket engines in space.

The engines in the fourth stage will be reignited three times, in a bid to master the technique that will enable ISRO to inject satellites into different orbits in a single launch. “It will be a validation of the technique that was tested in the PSLV-C34 mission and deployed in the subsequent C35 mission”, says B. Jayakumar, PSLV project director. The exercise will be conducted after all 31 satellites on PSLV-C38 have been injected into orbit.

“Once the last satellite has been separated from the rocket at a height of 520 km, the fourth stage of the rocket (PS4) comprising two liquid propellant engines will be shut down and reignited three times,” Mr. Jayakumar told The Hindu. While the first two firings are expected to last about six seconds each, the third restart is likely to fire up to 40 seconds.

The multiple reignition of the on board engines will validate the technique and provide ISRO with the mission flexibility to inject satellites into three different orbits in a single flight to reduce the launch cost and save time.

PSLV, the workhorse of ISRO, is capable of launching satellites into different types of orbits like Sun Synchronous Polar Orbit (SSPO), Low Earth Orbit (LEO) and Geosynchronous Transfer Orbit (GTO), as per the customer requirements. Even though ISRO has enough experience in long duration satellite missions employing multiple restart of the spacecraft’s Liquid Apogee Motor (LAM) engine, it was during the PSLV-C34 mission that it first attempted a reignition of the rocket engine. Subsequently, the PSLV- C35 mission placed eight satellites into two different orbits.

Student dreams to soar on satellite

When the PSLV-C38 rocket lifts off from the Satish Dhawan space port on Friday, it will carry with it the dreams and hopes of over 200 students of the Noorul Islam University at Thuckalay in Kanyakumari district. The students contributed to the design and development of a nano-satellite sharing space with the 30 others on board.

They were part of the team involved in the project to build NIUSAT, a satellite for disaster management and crop monitoring. The project which began in 2007 was supported by ISRO and is estimated to have cost ₹37 cr. Weighing 15 kg, NIUSAT was fabricated at a satellite laboratory set up on the campus. The university has also established a dedicated mission control centre for telemetry and telecommand operations and payload data reception. The satellite is equipped with an RGB camera for multispectral imagery with a resolution of 25 m from an altitude of 500 km.

‘Conceived in 2004’

“Over the 10-year period, the 200 students from the Aerospace, Aeronautics, Mechanical and Electronics and Communication engineering streams were part of the project during their course. Many of them spent time in the laboratory even during the vacation”, recalls Faizal Khan, Pro-Chancellor of the university. “The project was the brainchild of our Chancellor A.P. Majeed Khan and was conceived in the wake of the tsunami in 2004.”

As many as 16 scientists from ISRO and two industry partners provided critical support for the team.