PSLV carries reusable final-stage rocket, a 1st for India and the world.

The latest Polar Satellite Launch Vehicle (PSLV) take off from Sriharikota, Andhra Pradesh, at 11.37pm on Thursday, on a mission to help India notch up one more first in space technology— it will make use of the final stage of rocket as orbital platform for a satellite.

The fourth and final stage of the rocket normally turns into debris after ejecting a satellite. This time, the workhorse PSLV DL’s fourth stage, with a satellite built by school students strapped to its back, will continue orbiting the earth at a distance of 450km above it for six months, maybe more.

This gives Indian space scientists an innovative orbital platform for conducting experiments. The bonus is that Chennai-based school students who built Kalamsat, the world’s smallest student satellite, will also be able to conduct their own research.

The mission, called PSLV C-44, is India’s first this year and serves as a test for a new variant of the launch vehicle, the PSLV-DL, which has two strap-on motors.

PSLV is a launch vehicle with four stages—PS1, PS2, HPS3, and PS4 which is equipped with twin-liquid engines is equipped with twin liquid engines. After the launch vehicle enters space, it ejects the satellite and eventually becomes debris which is normally not recovered.

In the current mission, however, scientists at the Indian Space Research Organization (Isro) have powered up the fourth stage and given it an extended life of at least six months, so that it could serve as an experimental orbital platform.

The strategy is to move the fourth stage rocket (PS4) to a higher orbit and stabilise it by adding a power source. The orbital platform would enable scientists to conduct technology demonstrations and give an opportunity to school students across the country to perform experiments in space, through student satellites.

This is the ninth student satellite that India will fire off into space.

With this mission, Kalamsat will become the first payload to use PS4 as an orbital platform.

PSLV C44 also carries an imaging and surveillance satellite called Microsat for the Defence Research and Development Organisation (DRDO). Microsat will be separated at an altitude of 277km, in low-earth orbit.

“This year, the main focus of Isro is to expand its wings, to explore unknown places in space that have not been explored before" Isro chairman K. Sivan had said on 17 January, while announcing the first satellite mission for 2019. The thrust he said would also be on developing low-cost missions.

This was the 46th flight of the PSLV which, in 25 years, has carried out 43 successful missions, including the landmark Mars Orbital Mission and Chandryaan-1. It has undergone several technology upgrades since its first flight in September 1993 (Source:Livemint)