The Space-PNT Report #1
India's Navigation Constellation in November 2025: Performance Under Strain
I covered the implications of the failed launch of NVS-02 back in February. Much time has passed, and little has happened — or so it seems. Monitoring a constellation can be overwhelming, even if it is a small fleet like India’s NavIC system with 11 launches attempted since 2013. In order to simplify this effort and present a balanced and data-driven picture to stakeholders, I have roped in Aditya Jhunjhunwala and Krishi Tiwari to build an automated monitoring system to track the health of NavIC using open-source data and signals - and over time, all the world’s space-based PNT constellations.
The first version of the dashboard focuses on geosynchronous satellites — covering NavIC entirely, and directly extensible to Japan’s QZSS and China’s BeiDou (it has both GEO/IGSO and MEO satellites). Support for MEO constellations like the US GPS will be added in subsequent updates. If you are interested in early access to the dashboard or custom monitoring for your organization, please reach out to me here.
NavIC: A Constellation Under Strain
As of November 2025, India’s NavIC system is able to provide positioning services with four active satellites from the operational constellation — down from the designed seven-satellite architecture.
This first report reveals some interesting patterns worth examining. It tells a tale of two generations: the veteran IRNSS-1B (launched in 2014) and IRNSS-1I (launched in 2018) satellites are performing remarkably well, scoring 91.3 and 93.4 respectively out of a maximum score of 100 — with excellent orbital control (inclination deviations under 0.02°), while the newest satellite NVS-01 has deviated from its inclination specification significantly resulting in a score of 60.5.
Readers will note that IRNSS-1D is now in decommissioned and in a graveyard orbit. The re-orbiting maneuvers as mandated by the International Telecommunications Union (ITU) and the Inter-Agency Space Debris Coordination Committee (IADC) began on July 7th 2025 and finished on July 15th with the satellite in a lower inclination orbit (~20°) at a distance of 600km beyond its operational altitude. We will be dropping satellites that have been explicitly decommissioned from future reports.
What These Metrics Mean
Health scores combine orbital stability, and operational sustainability. Scores below 70 indicate satellites operating under constraint. The ‘Mean Drift’ values show how rapidly satellites are drifting from their assigned mean longitudinal positions — negative values indicate westward drift requiring regular correction maneuvers that consume propellant reserves. The scoring methodology is explained here.
The newer assets face different challenges. IRNSS-1E (2016) operates with a 60.6 health score, showing a 3.4° inclination deviation and a northward drift from 32.1° to 32.6° throughout 2025. For a geosynchronous PNT system such as NavIC, larger excursions north and south of the equator result in lower elevation angles for users in the southern and northern coverage areas respectively.
NVS-01, launched 18 months ago into a 5° (near) geostationary orbit, currently scores 60.5, with its inclination dropping southward from 3.5° to 2.8°. Interestingly, it has not performed any North-South corrections over the past 270+ days. The GEO satellites (IRNSS-1C, 1F and NVS-01) show a pattern of E-W station-keeping with limited N-S maneuvers, which may indicate careful propellant management employed by the operators at IRSCF in Hassan and Bhopal to stretch the life of the remaining satellites before replenishment.
Operational Performance
With just four satellites active, it becomes important to measure the operational performance of this reduced constellation. Dilution of Precision, or DOP, is one such metric to specify positional measurement precision. For the month of October 2025, the average PDOP (3-dimensional position component of DOP) was 11.11 (ranged from a minimum of 5.45 to a maximum of 82.42) — nearly thrice the value (larger values mean lower precision) achieved with a fully functioning 7-satellite constellation. A comparison with ISRO’s last published performance report (Q4 2021), see Chapter 2, shows that NavIC previously operated with DOP of around 4.
The current state means there is no redundancy. Should any satellite degrade, providing PNT capabilities across the entire service area will be challenging. IRNSS-1B, despite exhibiting excellent orbital stability and a high health score — is now over 11 years old, exceeding its original 10-year design life. Continued dependence on this veteran satellite introduces risk, as even well-behaved satellites beyond their intended lifespan have experienced failures.
Looking Ahead
This month’s report showed that NavIC is still capable of providing PNT services, though the system would certainly benefit from acceleration of the planned NVS launches to regain basic service, availability, redundancy and long-term sustainability. As with any space-based PNT system, there’s an ongoing balance between maintaining current operations and preparing for future needs. ISRO’s operational teams deserve recognition for maintaining some semblance of a service with the current constellation configuration.
As of date, the following questions remain open:
Can ISRO keep to the stated dates for launch of NVS-03 and accelerate production of NVS-04 to plug capacity gaps and prevent creation of a capability gap?
Should India prioritize constellation restoration over NavIC 2.0 development?
Who are impacted, and what compromises have been made since planned satellites have failed to make it to service?
In the Next Report
We will introduce the automated monitoring dashboard, expand coverage to Japan’s QZSS and and BeiDou-3’s GEO/IGSO system and analyze how other GNSS operators manage their constellations.
I hope you found this article useful. Please feel free to share this and others with your friends and colleagues. Connect with me on LinkedIn or email if you are looking for more detailed information on the topic or to collaborate.