GSLV-F18 Puts NVS-03 in Orbit: How India's GSLV Rocket and Satellite Orbits Work
ISRO's GSLV-F18 rocket lifted off from the Second Launch Pad of the Satish Dhawan Space Centre, Sriharikota (Andhra Pradesh), at 23:51 IST on 30 October 2026.
It placed the NVS-03 navigation satellite, weighing about 2,250 kg, into a Geosynchronous Transfer Orbit (GTO). A GTO is a long, oval-shaped orbit from which a satellite later climbs to its final position about 36,000 km above the Earth.
GSLV-F18 was the 20th flight of the Geosynchronous Satellite Launch Vehicle (GSLV). Its aim was very precise: the planned lowest point of the orbit was 170.36 km and the rocket achieved 170.31 km.
NVS-03 is the third satellite of the NVS series, the second generation of India's own navigation system, NavIC. It carries both Indian-made and imported atomic clocks and sends a new civilian L1 signal along with the older L5 and S-band signals.
The government said NVS-03, with its improved capabilities, will take forward India's self-reliance in critical technologies and support navigation services for ordinary people.
The launch came after the January 2025 setback, when NVS-02 reached its transfer orbit but could not climb further because a valve in its engine line did not open.
GSLV (Geosynchronous Satellite Launch Vehicle) Programme
The GSLV is ISRO's medium-lift rocket. Its job is to carry satellites of about 2 to 2.5 tonnes into a Geosynchronous Transfer Orbit, the first step towards the high orbit about 36,000 km above the Earth. It is used mainly for navigation, weather and communication satellites. Its most important part is the top stage, which burns super-cold liquid hydrogen and liquid oxygen: this is called a cryogenic stage.
The GSLV is India's standard rocket for NavIC satellites, which are too heavy for the PSLV to put into a transfer orbit. GSLV-F18 delivered NVS-03 into its transfer orbit with very high accuracy, which saves the satellite's own fuel for the climb to its final slot.
Orbit Classification: LEO, GTO, Sub-GTO and Geostationary Orbit
An orbit is the curved path a satellite follows as it keeps falling around the Earth without ever hitting it. Satellites are grouped by how high they fly and what shape their path has. A satellite close to the Earth moves very fast and circles the planet many times a day. A satellite far away moves slower and takes longer to go around once. The height chosen for a satellite depends on its job: taking photos, sending TV signals or telling you your location.
GSLV-F18 placed NVS-03 in a Geosynchronous Transfer Orbit with a low point of about 170 km. NVS-03 now has to fire its own engine to climb and settle into its geosynchronous slot at 111.75° East, where it will join the NavIC constellation.
Pyrotechnic (Pyro) Valves and Spacecraft Propulsion Systems
A pyro valve is a one-time valve on a spacecraft. It is opened or closed by firing a tiny explosive charge. Until it fires, it seals the fuel or oxidiser pipe completely, so dangerous propellants cannot leak during launch. Once fired, it cannot be reset. If it fails to open, the satellite's main engine cannot get its propellant.
The success of GSLV-F18 matters most if NVS-03 can climb out of its transfer orbit, which is exactly where NVS-02 got stuck. Flying with key valves already open removes the single point that failed last time.
- GSLV-F18 / NVS-03 launch: 23:51 IST, 30 October 2026, Second Launch Pad, Satish Dhawan Space Centre, Sriharikota
- GSLV-F18 is the 20th flight of the GSLV
- NVS-03 mass: about 2,250 kg; placed in GTO (perigee achieved 170.31 km against 170.36 km planned)
- NVS-03: third of the NVS series; signals in L1, L5 and S-band; indigenous and imported atomic clocks
- NavIC coverage: India plus about 1,500 km beyond its boundary
- GSLV: three stages (S139 solid core with four L40 strap-ons, GS2 Vikas stage, indigenous cryogenic upper stage); about 51.7 m, about 420 t
- First GSLV flight: April 2001 (GSLV-D1); first indigenous cryogenic success: January 2014 (GSLV-D5)
- NVS-01: GSLV-F12, 29 May 2023; NVS-02: GSLV-F15, 29 January 2025 (stranded in GTO)
- GEO altitude: 35,786 km; period: 23 h 56 min 4 s