An Indian Geosynchronous Satellite Launch Vehicle is counting down to liftoff at 1:12 a.m. EDT (0512 UTC) Monday with the first in a new generation of regional navigation satellites.

The GSLV Mk.2 rocket will loft the NVS 01 satellite to join India’s fleet of navigation spacecraft covering the Indian subcontinent and neighboring regions, augmenting coverage provided by global navigation satellite fleets operated by the United States, Russia, China, and Europe.

The nearly 170-foot-tall (51.7-meter) rocket will take off from the Second Launch Pad at the Satish Dhawan Space Center, located on Sriharikota Island on the Bay of Bengal approximately 50 miles (80 kilometers) north of Chennai. Liftoff is scheduled for 10:42 a.m. local time at the launch site.

The 27-hour countdown began Sunday, and ground crews took steps to fill the rocket’s second stage and four liquid-fueled boosters with storable hydrazine and nitrogen tetroxide propellants, according to the Indian Space Research Organization. In a reversal of the design of most launchers, the GSLV’s core stage burns pre-packed solid propellant, while its strap-on boosters consume liquid fuel.

The GSLV’s cryogenic third stage received its load of super-cold liquid hydrogen and liquid oxygen in the final hours of the countdown Monday ahead of liftoff of India’s fourth orbital launch of the year.

The sole payload aboard the GSLV Mk.2 rocket is the 4,920-pound (2,232-kilogram) NVS 01 navigation satellite, an Indian-built spacecraft heading for a position in geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator. The rocket’s hydrogen-fueled third stage will inject the NVS 01 satellite into an elongated transfer orbit, and the spacecraft will use its own propulsion to circularize its orbit in the coming weeks.

NVS 01 is the first in a second-generation series of satellites for India’s domestically-developed regional navigation system, called Navigation with Indian Constellation, or NavIC. India launched nine first-generation navigation satellites from 2013 through 2018, flying on the country’s smaller Polar Satellite Launch Vehicle.

The second-generation NVS satellites are larger in size and mass, requiring use of the heavier GSLV.

The launch Monday will be the 15th flight of India’s GSLV Mk.2 rocket, which has been upgraded since its debut in 2001 to use more powerful engines and an Indian-built upper stage to replace the Russian unit used on the initial GSLV flights. It will also be the first launch of a GSLV Mk.2 rocket since a launch failure in 2021.

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