After the 44.4-meter-tall PSLV rocket lifted off from the first launch pad at 9.10 am on Monday, it placed the primary satellite XPoSat into the desired orbit after 21 minutes of flight as intended

The rocket used for today's successful mission was the PSLV-DL variant, which has a lift-off mass of 260 tons. The fourth stage is configured as a 3-axis stabilised Orbital platform for conducting experiments.

After injection of XPOSAT, the PS4 stage will be re-started twice to reduce the orbit into 350 km circular orbit to maintain in 3-axis stabilized mode for Orbital Platform (OP) experiments.

ISRO on Monday successfully did a manoeuvring experiment by firing the fourth stage of a Polar Satellite Launch Vehicle rocket twice to conduct scientific experiments.

Later, scientists at the Bangalore-headquartered space agency fired the fourth stage of the PSLV rocket twice to reduce the altitude from 650 km to 350 km to conduct the scientific experiment in which 10 other payloads of various ISRO centres would be operational in the Low Earth Orbits under the PSLV Orbital Experimental Module-3 (POEM) experiment.

The rocket used for today's successful mission was the PSLV-DL variant, which has a lift-off mass of 260 tonnes. The fourth stage is configured as a 3-axis stabilised Orbital platform for conducting experiments.

The space agency conducted a similar scientific experiment using POEM-2 in the PSLV-C55 mission in April 2023.

The electrical power requirements of the fourth stage orbital platform are catered by Flexible Solar Panel in conjunction with 50 Ah Li-ion battery.

The orbital platform (PS4) consists of avionic systems to take care of navigation, guidance, control and telecommands and orbital platform altitude control systems to cater to the control to test the payloads, ISRO said.

Orbit Change And Passivation

After injection of XPoSat in 650km, 6 deg orbit, PS4 stage was lowered to 350km, ~9.6deg orbit, by restarting PS4 twice. The left out propellant in the PS4 was disposed through the Main engines as a pre cursor to enabling safety of PS4 stage in atmosphere re-entry experiments planned in future. The Oxidiser was let out first followed by Fuel in a predetermined sequence of operations. The existing scheme of Spent stage passivation by venting the tank pressure will also be active. Post passivation of PS4, the control of stage is transferred to POEM Avionics.

PSLV Orbital Experimental Module-3 (POEM)

PS4 stage is configured as a 3-axis stabilized Orbital platform for conducting experiments to space qualify systems with novel ideas. The PS4 Stage Orbital Platform Electrical power requirements are catered by Flexible Solar Panel in conjunction with 50Ah Li-Ion battery in battery tied configuration. The orbital platform consists of Avionic systems to take care of Navigation, Guidance, Control & telecommands and Orbital Platform Attitude Control System to cater to control of the platform to test the payloads. The payloads are as follows.

Among the 10 payloads are: Radiation Shielding Experiment Module by TakeMe2Space, Women Engineered Satellite by LBS Institute of Technology for Women, BeliefSat (an amateur radio satellite) built by K J Somaiya Institute of Technology, Green Impulse Transmitter by Inspecity Space Labs Pvt Ltd, LEATTD -- Launching Expeditions for Aspiring Technologies Technology Demonstrator by Dhruva Space Pvt Ltd.

RUDRA 0.3HPGP and ARKA 200 developed by Bellatrix Aerospace Pvt Ltd, Dust Experiment (DEX) built by PRL, ISRO and Fuel Cell Power System and Si based High Energy cell built by Vikram Sarabhai Space Centre are the others.