Countdown under way as ISRO prepares to launch NVS-03 tonight to rebuild India's NavIC navigation fleet
ISRO's GSLV-F18 rocket is set to lift off at 11:51 pm on Friday carrying NVS-03, a navigation satellite with an indigenous atomic clock that would restore India's NavIC constellation to the minimum strength needed for standalone positioning.
India's space agency ISRO is counting down to a late-night launch on Friday, with the GSLV-F18 rocket scheduled to lift off at 11:51 pm IST from the Second Launch Pad of the Satish Dhawan Space Centre at Sriharikota, carrying the NVS-03 navigation satellite into orbit.
The 24-hour countdown began at 11:51 pm on Thursday and is progressing, the agency said, with the launch to be telecast live from 11:20 pm. ISRO marked the day with a short message: "Launch Day! GSLV-F18 is set to launch NVS-03."
The vehicle is a heavyweight. The Geosynchronous Satellite Launch Vehicle stands about 50 metres tall with a lift-off mass of around 420 tonnes across its three stages, and Friday's flight is the 20th mission of the GSLV programme — a workhorse rocket that has been flying since 2001.
Its passenger matters more than its size. NVS-03, weighing about 2,232 kg, is the third satellite in India's second-generation NVS series and will be placed into a geosynchronous transfer orbit with a perigee of 170 km, an apogee of 37,023 km and an inclination of 20.75 degrees, from where it will be raised to its operational slot.
The satellite carries navigation payloads operating in the L1, L5 and S bands, plus a ranging payload in C-band. The addition of the L1 signal — the same band used by widely available receivers — is expected to widen the range of devices that can use India's navigation signals, alongside the existing L5 and S-band services.
At its heart sits a clock built at home. Precise timing is the foundation of satellite navigation, and NVS-03 carries an indigenous rubidium atomic clock developed by the Space Applications Centre in Ahmedabad — the third Indian-built atomic clock to fly, following those on NVS-01 and NVS-02 — alongside procured clocks.
The launch carries unusual weight because of the state of the fleet it joins. NavIC, India's answer to GPS, was designed as a seven-satellite constellation covering India and a region extending about 1,500 km beyond its borders. But Space Minister Jitendra Singh told Parliament in a written reply on 29 July that only three of the seven planned satellites were currently providing navigation services — and at least four are needed for basic, standalone positioning. Timing services have continued to function in the meantime.
A successful NVS-03 deployment would lift the operational fleet back to four, restoring that minimum positioning capability — though the constellation would still be three satellites short of its full design strength, a gap ISRO plans to close with further NVS launches.
The mission also flies in the shadow of a failure. NVS-03's predecessor, NVS-02, suffered an anomaly after launch, and an ISRO review reported in February 2026 identified a disconnected connector in the drive signal to an oxidizer-line pyro valve as the likely cause. For this flight, the agency has chosen to fly with the pyro valves already open, removing that failure mode from the sequence entirely.
If the rocket performs as planned tonight, orbit-raising manoeuvres will follow over the coming days before the satellite can be checked out and brought into service; ISRO has not yet announced when NVS-03 will formally join the navigation fleet. For a country that has pushed NavIC into phones, vehicles and strategic systems, tonight's 11:51 pm lift-off is less a routine launch than a repair job on national infrastructure — conducted, as usual, in full public view.
