4 failures in 8yrs- ISRO's troubles with strategic space missions

The rare and unusual mid-flight failure of India's PSLV-C61 rocket on May 18th, 2025, and the subsequent loss of the strategic EOS-09 satellite is a serious setback for India. However, the latest loss of a national security-related satellite is one among many in recent years. Between 2021-25, this author has reported in detail about three failures of India's strategic space missions. Prior to that, there was a PSLV mission failure in 2017. Unfortunately, all four satellites lost/affected in these missions were critical for India's national security and strategic needs.

As per publicly available information, each mission failure over the last eight years was caused by a different component/system. This re-emphasizes that rocketry is a
zero-error business, where even the smallest of errors or defects can lead to catastrophic failures and immense losses. While such losses offer valuable lessons for future missions, it is also important to note that these failures are denying and delaying deployment of several important space-based capabilities developed by Indian scientists.

Going by rocket and satellite cost estimates, four mission failures in the last eight years would have cost the Indian Government at least Rs.1250crores(approx $146mn). Further, the Government would have to spend the same amount of money once again to redo these missions. Also, one must factor in the cost of the lost opportunities. Because, in the absence of these homegrown strategic satellites, India would have to purchase satellite-based services from foreign firms. Having to commit resources to redo failed missions would also considerably slowdown India's planned rocket launch missions, and the overall timeline of executing space launches.

Going by launch statistics from recent years, the Indian space agency has done 41 rocket launch missions between 2017 and May 2025. Of these, four have ended up as failures and all four happen to be national security and strategic missions. Here's an analysis of ISRO's troubles with recent strategic space missions, the timing of those failures, and the strategic impact of the same.

August 2017, PSLV-C39/IRNSS-1H

Indian Regional Navigation Satellite System(IRNSS), later known as Navigation with Indian Constellation(NAVIC) is a Position, Navigation, Timing service meant to be used by the various ministries of the Indian Government and the Armed Forces. Simply put, NAVIC is comparable to an Indian-made equivalent of Global Positioning System.

Unlike the American GPS/Russian GLONASS/Chinese Beidou which works worldwide, NAVIC works only within the Indian landmass and 1,500kms from India's borders. Therefore, it is a regional system covering India's immediate neighbourhood. Notably, NAVIC was approved following the 1999 Kargil war between India and Pakistan, when US denied/degraded GPS services that would support Indian military operations.

During the late-night launch of PSLV-C39, all flight events took place exactly as planned, except heat shield separation. This resulted in satellite separation occurring within the heat shield. The satellite remained inside the heat shield resulting in the unsuccessful mission.

In April 2018, ISRO launched the PSLV-C41 rocket carrying the IRNSS-1I satellite, which was meant to serve as a replacement for the lost satellite and complete the NAVIC constellation.

August 2021, GSLV-F10/EOS-03

Amid the COVID-19 pandemic, ISRO had launched a sophisticated earth-imaging satellite known as GISAT-1, aboard the GSLV-F10 rocket. GISAT-1 or EOS-3 was an agile earth observation satellite, which can use different types of imaging technologies to provide a constant monitoring of a region of interest/calamity/weather pattern.

GISAT-1 was meant to provide almost real-time imaging of large regions of interest at frequent intervals, quick monitoring of natural disasters, episodic events, and also obtain spectral signatures for agriculture, forestry, mineralogy, disaster warning, cloud properties, snow & glaciers, and oceanography.

Unlike Low Earth orbit satellites(placed at approx 600kms altitude) that re-visit the same spot approximately once a week, GISAT-1 was meant to stay perched 36,000kms above the Indian subcontinent and help maintain a constant vigil of a large area. This mission was ready for launch in early-2020, but delayed for "technical reasons". Finally, the rocket lifted off on August 12th 2021, but the mission ran into trouble after a malfunction in the Cryogenic upper stage that was meant to place the satellite into orbit. ISRO later revealed that a valve leak in the liquid hydrogen tank led to the failure.

Though not directly related, this earth-imaging satellite was being launched at a time when India was dealing with China's aggressive military posturing along the Line of Actual Control.
Till May 2025, ISRO has not launched a replacement for the lost GISAT-1 satellite. It is likely to be launched before March 2026, it is learnt.

January 2025, GSLV-F15/NVS-02

With the first-generation of NAVIC satellites nearing their end-of-life, ISRO began replacing it with a heavier series of five satellites known as NVS. NVS-01, the maiden satellite in this series was launched successfully in May 2023. The next one, NVS-02 was launched in January 2025, in what was the 100th rocket launch from the Indian spaceport in Sriharikota.

While the GSLV rocket accomplished its task of placing the NVS-02 satellite in the initial orbit, the satellite encountered an anomaly, which prevented it from firing its on-board engines and moving to the final orbit. Satellites are moved from one orbit to another by firing their liquid-fuelled engines that burn a fuel and oxidizer combination. In this case, it has not been possible to fire the engine and raise the satellite's orbit, due to an issue with the valve that releases the oxidizer.

The satellite was launched into a Geostationary Transfer Orbit (GTO), which is usually used as an initial parking orbit for heavy satellites. Approximately, the satellite was launched into an orbit that is highly elliptical- 170kms above Earth at its nearest approach (perigee) and 36,500kms at its farthest approach from Earth (apogee). Typically, a series of engine firings are performed to place the satellite into a circular orbit, where it is evenly 35,700 km above Earth. However, NVS-02 remained stuck in GTO.

ISRO had stated that the satellite systems are healthy, elaborating that it is generating power from its solar panels and communicating with the stations on Earth. "Alternate mission strategies for utilising the satellite for navigation in an elliptical orbit is being worked out," it was added. However, the satellite's long-term survival and its core purpose being accomplished is highly uncertain. ISRO has also not provided further updates about this satellite. Going forward, ISRO is expected to launch an NVS-series satellite every year. Therefore, it would be at least four years before the five-satellite NVS-series is fully operational.

May 2025, PSLV-C61/EOS-09

On Sunday, 18th May, barely six minutes after liftoff, ISRO's PSLV-C61 rocket faced trouble mid-flight. "Up to the second stage performance was normal. Third stage ignited, but we made an observation regarding its functioning. Mission could not be accomplished. We are studying the data," said ISRO Chief Dr. V. Narayanan regarding the status of the four-stage PSLV rocket that was supposed to perform an 18-minutes-long mission.

EOS-09 is a radar imaging satellite(earlier known as RISAT) that is capable of day and night imaging. It can see through clouds, deliver images under all weather conditions. This 1,700kg satellite was meant to have an operational life of at least five years.

Over a dozen Indian Parliamentarians, who are part of the Parliamentary Standing Committee of Science and Technology were at the spaceport in Sriharikota to witness ISRO's 101st rocket launch mission. Notably, the PSLV is ISRO's most-flown rocket and has a great track record of launching over two hundred satellites belonging to India and foreign customers. In its 63 flights so far, PSLV has had only four major setbacks - three failures and one partial success.

Addressing journalists at the spaceport, the ISRO Chief elaborated on the observations. "The third stage of the PSLV uses a solid-fuel motor system. There was a fall in the chamber pressure in the motor case. We are studying the entire performance," Dr. Narayanan said.

The failed launch of this strategic satellite comes a week after Nuclear-armed neighbours India and Pakistan have announced a ceasefire, following three days of a rapidly escalating war-like situation. However, it must be emphasized that the space launch mission taking place at this time is a mere coincidence. The PSLV rocket takes a little over a month to assemble, and it takes well over a year to build a satellite like EOS-09.

It would take more than a year or two for ISRO to build and launch a replacement for the EOS-09 satellite.