Over a year after the NVS-02 navigation satellite failed to reach its intended orbit, the Indian Space Research Organisation (Isro) has revealed what caused the mission setback and the corrective steps taken since then.
NVS-02, the second satellite in India’s NVS navigation series, was launched successfully on January 29, 2025 aboard the GSLV-F15 rocket. The spacecraft was placed into an elliptical transfer orbit measuring 170 km at its closest point to Earth and 37,785 km at its farthest.
The satellite separated normally from the rocket, and initial operations, including deployment of its solar panels and stabilising its orientation for power generation, were completed without issue.
However, the next critical step, raising the satellite from its elongated elliptical path into a circular operational orbit, could not be performed.
Isro constituted an Apex Committee to investigate the anomaly. After reviewing telemetry data (signals sent back by the satellite about its health and systems) and running detailed simulations, the panel identified the root cause.
According to Isro, the problem occurred in the “pyro valve” system of the satellite’s propulsion setup. A pyro valve is a small explosive-triggered device used to open fuel lines in spacecraft engines. In simple terms, it acts like a one-time switch that allows propellant, in this case, oxidizer, a chemical that helps fuel burn in space, to flow into the engine for orbit-raising maneuvers.
The committee found that the electrical drive signal meant to trigger the oxidizer-line pyro valve did not reach it.
The most likely reason was that at least one electrical contact inside a connector became disengaged in both the main and backup circuits. Because the valve never opened, the engine could not fire, preventing the spacecraft from moving into its final orbit.
Isro said the investigation led to a set of recommendations to improve redundancy, meaning having stronger backup systems, and increase the reliability of pyro mechanisms in future missions.
These corrective measures were implemented in the CMS-03 spacecraft, which was launched on November 2, 2025 aboard the LVM-3 M5. Isro confirmed that the pyro systems on CMS-03 functioned normally, and the satellite was successfully placed into its intended orbit.
The space agency stated that the lessons learned from NVS-02 will be applied to all future missions, reinforcing safeguards to prevent similar issues. The disclosure marks a rare and detailed public explanation of a technical anomaly, showing Isro’s focus on transparency and mission reliability.
