India launches first in new generation of navigation satellites

An Indian Geosynchronous Satellite Launch Vehicle lifted off Monday with the first in a new generation of upgraded regional navigation satellites designed to be interoperable with other countries’ global navigation networks.

The GSLV Mk.2 rocket deployed the NVS 01 satellite into orbit 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 took off at 1:12 a.m. EDT (0512 UTC) 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 occurred at 10:42 a.m. local time at the launch site.

The 27-hour countdown began Sunday. Ground crews filled 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 was 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 injected the NVS 01 satellite into an on-target elongated transfer orbit, and the spacecraft will use its own propulsion to circularize its orbit in the coming weeks, ISRO said.

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. The network is also called the Indian Regional Navigation Satellite System.

India launched nine first-generation navigation satellites from 2013 through 2018, with each one 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 GSLV Mk.2 rocket's third stage released the NVS 01 satellite into orbit about 18 minutes after launch. Data from the rocket confirmed the GSLV Mk.2 placed its payload into a good orbit, according to S. Somanath, chairman of ISRO.

ISRO confirmed the NVS 01 satellite unfurled its power-generating solar panels a few minutes after the spacecraft separated from the GSLV Mk.2 rocket. NVS 01 is heading for geosynchronous orbit at an inclination of about 5 degrees to the equator, where it will join the operational satellites that make up the Indian Regional Navigation Satellite System.

ISRO said in 2021 the NVS 01 satellite will replace the the IRNSS 1G satellite, which suffered problems with its navigation payload.

Six of India's first-generation navigation satellites are currently providing positioning and timing services. One was lost in a launch failure in 2017, and two more encountered technical problems with their atomic clocks, which the satellites use to time-tag their L-band navigation signals to help measure distance between the spacecraft and a user on the ground.

The new NVS satellites will debut a new Indian-made atomic clock design to replace the Swiss-made clocks on older satellites, and the new generation of spacecraft will incorporate a new L-band signal, called L1, alongside the existing L5 signal.

In remarks after Monday's launch, Somanath said the new-generation satellites have more secure navigation signals and will be more civilian-friendly.

"This is one of five series of satellites in this new configuration that are to be launched," Somanath said.

"The launch of NVS 01 is an event which all of us in the navigation community have been looking forward to for quite some time because of two reasons," said KVS Bhaskar, ISRO's satellite director for Monday's mission. "One is we are including the popular civilian band L1, and the inclusion of this band will make us interoperable with international operators. The second, and the most important reason, is we have included our very own indigenous atomic clock."

"We are going to make this NavIC system fully functional and operational for the benefit of this nation," Somanath said. "There's a huge amount of opportunity that is waiting for us to exploit in the future."

The launch Monday was 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 was also be the first launch of a GSLV Mk.2 rocket since a launch failure in 2021.

Investigators probing the 2021 launch failure determined a leaky vent and relief valve on the GSLV Mk.2's cryogenic third stage diminished pressure levels in the upper stage's liquid hydrogen fuel tank. The third stage engine failed to ignite, and the rocket and its Earth observation satellite payload fell back to Earth.

"I’m very happy that the corrections, the modifications, in the cryogenic stage that we have done in this phase, as well as the lessons that we learned out of it to make our cryogenic stage more reliable, have really made benefits," Somanath said.

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