The Indian Space Research Organisation’s (ISRO) successfully launched the Launch Vehicle Mark 3 (LVM3) with the BlueBird Block-2 satellite on Wednesday (December 24, 2025) morning, from the second launch pad of the Satish Dhawan Space Centre in Sriharikota.

The LVM3-M6 placed the BlueBird Block-2 satellite into Low Earth Orbit about 15 minutes after lift off.

This is the largest commercial communications satellite to be deployed in Low Earth Orbit. BlueBird Block-2 satellite is also the heaviest payload to be launched by LVM3 from Indian soil.

The BlueBird Block-2 communication satellite is developed by AST SpaceMobile, USA, and is part of a next-generation BlueBird Block-2 communication satellite, designed to provide space-based cellular broadband connectivity directly to standard mobile smartphones.

“BlueBird block-2 mission is part of a global LEO constellation to provide direct-to-mobile connectivity through satellite . This constellation will enable 4G and 5G voice and video calls, texts, streaming, and data for everyone, everywhere, at all times. It features a 223m² phased array, making it the largest commercial communications satellite ever deployed into low Earth orbit,” ISRO said.

This was the sixth operational flight of LVM3 and third dedicated commercial mission.

“In its earlier missions, LVM3 successfully launched Chandrayaan-2, Chandrayaan-3, and two OneWeb missions carrying 72 satellites. The previous launch of LVM3 was the LVM3-M5/CMS-03 mission which was successfully accomplished on November 02, 2025,” ISRO said

The Indian Space Research Organisation (ISRO) has successfully demonstrated the boot-strap mode start test on the CE20 Cryogenic engine which powers the upper stage of the Launch Vehicle Mark -3 (LVM3) rocket.

The test on the CE20 cryogenic engine, which was successfully conducted under vacuum conditions in the High-Altitude Test (HAT) facility at ISRO Propulsion Complex, Mahendragiri on November 7, for a duration of 10 seconds is an important development towards enhancing the restart capability and mission flexibility of future LVM3 flights.

Though the CE20 cryogenic engine, powering the LVM3 upper stage, is already qualified for operation at thrust levels ranging from 19 to 22 tonnes in flight with a single start, and also for the Gaganyaan missions, during nominal operation, the engine ignition is initiated under tank head conditions, followed by the start of turbo pumps using a stored gas start-up system.

“For future missions, multiple in-flight restarts of the CE20 engine will be required for mission flexibility towards multi-orbit missions. However, with the present configuration, each restart demands an additional start-up gas bottle and associated systems, leading to a reduction in vehicle payload capability. Hence, achieving boot-strap mode start — where the engine builds up to steady operation without external start-up assistance — is essential,” ISRO stated.

During the test, a multi-element igniter was employed in both the thrust chamber and gas generator to facilitate boot-strap starting.

“In this test, following the ignition of the thrust chamber, the gas generator was ignited under tank head conditions, and the turbo pumps were started without the use of the start-up system. Subsequently, boot-strap mode build-up and steady-state operation of the engine were successfully demonstrated,” ISRO stated.

The space agency said that with this achievement, ISRO has successfully demonstrated boot-strap mode starting of a gas-generator cycle cryogenic engine without any auxiliary start-up system, perhaps for the first time in the world.