States » SouthPosted at: Oct 29 2026 4:24PM


24 hr countdown for GSLV-F18/NVS-03 NavIC mission to begin at 2351 hrs tonight

Chennai, Oct 29 (UNI) The 24 hour countdown for tomorrow night's key GSLV-F18/NVS-03 NavIC mission will begin at 2351 hrs on Thursday night.
The countdown for the launch will commence 24 hrs before the launch, ISRO sources told UNI.
After the Mission Readiness Review gives the nod, the countdown will commence for filling propellants in the three-stage 50 m tall vehicle having a lift-off mass of 420 tonnes.
In a significant mission aimed at giving a further push to opertionalise the NavIC constellation to strengthen the defence needs, the GSLV-F18 carrying the 2,250 kg NVS-03 Navigation satellite will be launched from the Second Launch Pad from the spaceport on Sriharikota at 2351 hrs tomorrow, lighting up the night skies.
And after a flight journey of about 20 minutes and after the ignition and separation of all the three stages, the GSLV-F18 will inject the NVS-03 spacecraft into a Geosynchronous Transfer Orbit (GTO) at a perigee of 170 km and an apogee of 37,023 km with an inclination of 20.75 deg.
Navigation with Indian Constellation (NavIC) is India's independent regional navigation satellite system designed to provide accurate Position, Navigation and Timing (PNT) service to users in India as well as the region extending about 1,500 km beyond the Indian landmass, which is its primary service area.
NVS-03 is the 3rd satellite in second generation navigation satellite system (NavIC eries) envisaged for providing continuity of navigation services for the first generation IRNSS series. The satellite carries Indigenous Atomic clock, along with the procured Atomic clocks. It also includes L1 signal in addition to existing L5/S signals with Coverage over India land mass and a region extending 1500 km around Indian geopolitical boundary, ISRO said.
It was a highly significant mission as it was scheduled amid the urgent need to strengthen its NavIC constellation in the wake of fast changing geo-political situations.
The launch was also equally very important as it comes after the setback of two kack-to-back PSLV missions. The Space Agency returned back to winning way with the successful 'Eye in the sky' GSLV-F17/EOS-05 Earth Observation Satellite (GISAT-1A) mission last month, and buoyed by this ISRO is embarking on yet another push towards full operationalisation of India's indigenous satellite navigation system NavIC.
This launch delayed for a while, comes in the backdrop of failure of NVS-02 launched in January last year onboard GSLV-F15. Though the satellite was placed in the GTO orbit, it could not be raised to its designated geostationary orbit because of a glitch in the pyro valve which resulted in the Liquid Apogee Motor (LAM) in the spacecraft not getting the required oxidiser flow.
An Apex Committee formed to study the failure, found the reasons, studied it in detail and made some recommendations based on which all corrective measures were successfully implemented in the CMS-03 satellite launched on November 2, 2025, by LVM-3 M3 and the pyro systems performed satisfactorily.
Though sources in ISRO, when contacted by UNI, was tightlipped on it, according to reports, for the first time in its 51-year history, the Space Agency will launch the GSLV-F18 mission with the pyro valves onboard the satellite open. The failure of the NVS-02 was due to drive signal not reaching the pyro valve in the oxidiser line. The disengagement of at least one contact was said to be the reason for the satellite not able to fire to its designated GTO. As the pryo valve remained closed and the oxidiser could not reach the engine and the NVS-02 was stranded in the orbit.
In this present mission, once NVS-03 was injected in to the GTO, it would be manoeuvred into the 37,023 km Geostationary orbit by firing the onboard Liquid Apogee Motors(LAM) with the pyro valve playing a key part.
Initially named Indian Regional Navigation Satellite System (IRNSS), it was rechristened as NavIC (Navigation with Indian Constellation) aimed at providing PNT services across India and upto 1,500 km beyond its borders. The NavIC contains a constellation of seven satellites -- three in GTO and four in inclined GTO. NVS-01 was in orbit, NVS-02 has failed, NVS-03 is set to take flight tomorrow and it would be followed by NVS-04 and NVS-05.
NavIC satellites are crucial for the Indian Armed forces for missile navigation,precise positioning and coordination of warships at sea and indigenous navigation support for troops movement and combat aircraft. Mandatorily there should be at least four NavIC satellites in GTO for the Indian Army as it would help in maintaining strategic autonomy and gain tactical advantage as modern military hardware such as ballistic missiles and precision-guided munitions require accurate PNT signals for effective functioning.
India has so far launched 11 Navigation satellites of which only three IRNSS-1B, IRNSS-1L and NVS-01 which adds L1 band support, are providing the requisite services and NVS-03 will be the fourth. After NVS-03 comes to service ISRO could activate the NavIC system.
The success of NVS-03 mission would restore the standalone 3D positioning services for the NavIC system completing the mandatory requirement of four satellites for the benefit of the Indian Armed forces. NavIC offers dual services -- standard positioning service for civilians and an encrypted Restricted Service for authorised users like the Indian Military.
After the failed NVS-02 mission, another concern surfaced with the IRNSS-1F satellite, which was launched in March 2016. After completing its 10-year design life, the satellite's final onboard rubidium atomic clock failed. "On 13th March 2026, the procured on-board Atomic clock stopped functioning. However, the satellite will continue to function in-orbit for various societal applications to provide one way broadcast messaging services," according to ISRO.
Following back-to-back PSLV mission setbacks (PSLV-C61 on May 18, 2025 and PSLV-C62 on January 12, 2026) and earlier orbital and clock issues, ISRO has adopted a cautious, review-heavy approach Since the second successive failure of reliable and workhorse PSLV rocket, the space agency has adopted a cautious approach to launches—to understand and rectify the anomalies that caused the failures.
Against this backdrop, the upcoming NVS-03 launch assumes significance. The new satellite is expected to contribute to strengthening the NavIC constellation and increase the availability of navigation services.
The NavIC constellation was developed by ISRO to provide India with an independent satellite-based positioning, navigation and timing system. Unlike systems such as the US Global Positioning System (GPS), Europe's Galileo and Russia's GLONASS, NavIC was conceived primarily to meet India's own navigation requirements. NavIC is more accurate than GPS according to scientists.
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