A $100 Million Problem? ISRO’s NVS-02 Navigation Satellite Stuck in Orbit
3rd Feb 2025
The fate of India’s latest navigation satellite NVS-02 is now a Rs.600 crore puzzle.
The 2,250 kg NVS-02 that was placed in a Geo Transfer Orbit (GTO) launched on 29 January 2025 remains stuck there with the failure of the pyro valve to pump in oxidiser for the fuel to burn, making it impossible to raise it to the intended Geostationary Orbit.
The GSLV rocket costs approximately about Rs.300 crore and the NVS-02 satellite costs about a similar amount, a former senior official of ISRO said on the condition of anonymity.
It is a first-of-its-kind failure for ISRO, which has orbited several earth observation and communication satellites, retired senior officials of the space agency said.
What Went Wrong with NVS-02?
On January 29 morning, India, in textbook style, orbited its second of its second-generation navigation satellite NVS-02 with its Geosynchronous Satellite Launch Vehicle (GSLV) rocket.
Interestingly, it was the 100th rocket that flew from the Sriharikota spaceport.
Just over 19 minutes into its flight, the GSLV rocket spat out NVS-02 into GTO.
On the condition of anonymity a former senior official of Indian Space Research Organisation (ISRO) said normally the satellite’s orbit would have been raised to its final position viz., the Geostationary Orbit within two or three days after it was put into GTO.
The satellite’s orbit will be raised by firing the liquid apogee motors (LAM).
However for four days, ISRO remained silent on the satellite orbit raising status.
And only the fifth day evening ISRO in a statement said: “Subsequent to the launch, the solar panels on board the satellite were successfully deployed and power generation is nominal. Communication with the ground station has been established. But the orbit raising operations towards positioning the satellite to the designated orbital slot could not be carried out as the valves for admitting the oxidizer to fire the thrusters for orbit raising did not open.”
“The satellite systems are healthy and the satellite is currently in elliptical orbit. Alternate mission strategies for utilising the satellite for navigation in an elliptical orbit is being worked out,” ISRO added.
Prior to that, reliable sources had told about the failure of the pyro valve of NVS-02 supplying the oxidiser did not open, and hence, the LAM and the thrusters did not fire.
Only the fuel supply was there and without oxidiser fuel could not be burnt.
The stumbling satellite was stabilised in GTO using its gyro wheels.
One of the reasons said for the pyro valve not opening is there could be a fault with the electrical connector, it is learnt.
ISRO Chairman Dr. V.Narayanan who is a rocket and spacecraft expert said: “We will be raising the orbit using the thrusters with the available propellant. The satellite’s condition is healthy.”
He said: “The satellite will be used for navigation purposes only.”
When queried about the failure of pyro valve failure Narayanan reiterated that the satellite will be raised using the thrusters.
If the pyro valve does not open then the NVS-02 satellite will not be used for navigation purposes nor it could be used as an earth observation satellite as the necessary payloads are not there, experts said.
The Consequences of NVS-02’s Failure
The NVS-02 was to replace the Indian Regional Navigation Satellite System -1E (IRNSS-1E) satellite – part of the first generation satellite series.
The NavIC (Navigation with Indian Constellation) system provides accurate Position, Navigation and Timing (PNT) services to the users in India and to the region extending about 1,500 km beyond the country’s land mass.
As of now NavIC provides two types of services, namely, Standard Positioning service (SPS) and Restricted Service (RS).
NavIC’s SPS provides a position accuracy of better than 20 m and timing accuracy better than 40 ns (nano seconds) over the primary service area, ISRO had said.
Five second generation NavIC satellites will augment NavIC’s base layer constellation with enhanced features for ensuring continuity of services, ISRO earlier said.
Speaking to this correspondent prior to his retirement as ISRO Chairman Dr.S.Somanath said: “NVS series consists of five satellites and will work along with earlier ones in L5 and S band. The L1 band is only in NVS-01 and 02. A minimum of four satellites are needed to get a navigation solution at any time and more to improve accuracy. In the future we have to increase the size of the constellation to nine to extend range.”
Somanath said the next three NVS satellites will be launched one each at a six months interval and the life span of each satellite will be 10-15 years if electronics don’t fail.
The NVS series of satellites incorporates L1 band signals additionally to widen the services and increase the NavIC’s adoption rate. The L1 signals offer better location based services in the consumer segment.
One of the spin-off benefits of the IRNSS is the indigenous development of atomic clocks by India, a shining example of the Make in India programme, Narayanan had said.
With the imported clocks failing in some of the IRNSS satellites, India decided to develop its own atomic clocks saving about Rs.3 crore per satellite.
Each IRNSS satellite carried three atomic clocks.
The first of the second generation NavIC NVS-01 was orbited on 29 May 2023 by GSLV-F12 rocket with Indian atomic clock.
“For the last five years no failures were seen after we suggested and implemented corrections in them. ISRO clocks will be the primary in all the NVS satellite series,” Somanath had said.
Can ISRO Save NVS-02 or Is It a Lost Cause?
“What ISRO could do now with NVS-02 is to check the working of the India-made atomic clocks and also use the satellites for messaging services,” an industry expert not wanting to be quoted said.
The NVS-02 uses a combination of indigenous and procured atomic clocks for precise time estimation and both are compatible providing similar timing solutions, Somanath added.
According to ISRO, the NVS-02 satellite is configured with navigation payload in L1 (primary frequency band used by satellite constellations), L5 (used for high precision services) and S (commonly used in satellites) bands in addition to ranging payload in C-band like its predecessor-NVS-01.
Out of the seven IRNSS satellites that were orbited earlier, four are functional providing Position, Navigation and Timing service and the remaining ones offer safety-of-life messaging services.
The full constellation of seven satellites is expected to be completed in the coming years, Dr. Jitendra Singh, Minister of State, Personnel, Public Grievances Pensions and in the Prime Minister’s Office told the Parliament.
But the moot question that needs an answer for the NVS-02 issue is why the pyro valve did not open as India had sent several satellites earlier and did not face such a problem, a retired senior official of ISRO said.
Further, ISRO has to focus on its quality control aspects as the similar valves are to be used in its proposed human flight mission Gaganyaan.
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