Sriharikota, Nov 2: The Indian Space Research Organisation (ISRO) is preparing to launch its heaviest communication satellite, CMS-03, on Sunday using the country’s most powerful rocket, the LVM3-M5. The 43.5-metre-tall heavy-lift launch vehicle will carry the 4,410 kg satellite into a Geosynchronous Transfer Orbit (GTO).

ISRO officials confirmed that the countdown for the launch, taking place from the spaceport in Sriharikota, is “progressing smoothly.” Once launched, CMS-03 will become the heaviest satellite ever placed into GTO from Indian soil — and the heaviest one to be launched using an entirely Indian-built rocket.

Until now, ISRO has relied on France-based Arianespace to launch its heavier communication satellites weighing over 4,000 kg. The agency’s previous heaviest satellite, GSAT-11 (5,854 kg), was launched on December 5, 2018, aboard an Ariane-5 VA-246 rocket from the Kourou spaceport in French Guiana.

Dubbed the “Bahubali” of Indian rockets for its immense lifting capability, the LVM3-M5 has been fully assembled and integrated with CMS-03. The launch vehicle has been positioned on the second launch pad for final pre-launch operations.

In a social media post on Sunday, ISRO announced: “Launch Day for LVM3-M5. India’s heavy-lift rocket will launch CMS-03 today at 17:26 hours.”

An ISRO official added that the 24-hour countdown, which began on Saturday at 5:26 pm, is proceeding as planned.

CMS-03 is a multi-band communication satellite that will provide services over a wide oceanic region including the Indian landmass. CMS-03, weighing about 4400kg, will be the heaviest communication satellite to be launched to Geosynchronous Transfer Orbit (GTO) from Indian soil. The previous mission of LVM3 launched the Chandrayaan-3 mission, where in, India became the first country to land successfully near the lunar south pole.

The launch vehicle has been fully assembled and integrated with the spacecraft and has been moved to the Launch Pad on October 26, 2025 for further pre-launch operations.