In a historic collaboration, India and the United States have successfully launched the Nasa-Isro Synthetic Aperture Radar (Nisar) satellite. Valued at approximately $1.3 billion, Nisar is the costliest civilian Earth observation satellite ever developed and marks the most ambitious joint science mission undertaken by the two countries.

Weighing 2,392 kilograms, Nisar has been placed in a sun-synchronous orbit and will circle the Earth every 97 minutes. Equipped with advanced radar systems, it will scan the planet with high precision, day and night, in all weather conditions.

GSLV’S FLIGHT OF REDEMPTION

What makes this launch even more remarkable is not just the satellite, but the rocket that carried it into space. Isro used its powerful Geosynchronous Satellite Launch Vehicle, GSLV-F16, to place Nisar into a sun-synchronous orbit.

At the core of the GSLV is its cryogenic upper stage, a high-performance 100% indigenous engine that gives the rocket its final thrust into orbit. But this engine is more than a scientific triumph.

It is a symbol of India’s resilience and the personal redemption of the man who once led its development: Nambi Narayanan.

Ironically, the very technology that was once denied to India was used to launch a satellite for the country that tried to block it. The United States, which once opposed India’s efforts to acquire cryogenic engine technology, is today a customer of it.

To understand why this moment matters so deeply, one must go back to where the story began, three decades ago, when a scientist’s dedication collided with geopolitics and nearly cost him everything.

THE NAMBI SAGA

By the early 1990s, Isro was aiming to graduate from the PSLV to the GSLV system. For these more powerful rockets, Isro scientists explored three types of fuel systems. The first was earth-storable fuels, liquids that can be stored at normal temperatures, such as unsymmetrical dimethylhydrazine (UDMH) and nitrogen tetroxide. These were easier to handle but offered lower performance.

The second option was semi-cryogenic engines, which use a mix of kerosene and liquid oxygen. They are more efficient but were still under development. The third, and most powerful, was cryogenic propulsion, which uses liquid hydrogen and liquid oxygen stored at extremely low temperatures.

Though technically complex, cryogenic engines offered the highest thrust and were ideal for the rocket’s upper stage. Cryogenics was the clear choice, but also the hardest to master.

Cryogenic engines use super-cooled liquid hydrogen and liquid oxygen as fuel, stored at temperatures as low as –250C. They produce extremely high thrust, making them essential for launching heavy satellites into high orbits. But the very features that make cryogenic engines powerful also make them incredibly complex. Storing and handling such super-cooled liquids requires advanced materials. Even the slightest heat leak can cause the fuel to evaporate or create pressure imbalances.

Building a fully operational engine would take years, and India’s satellite programme couldn’t wait. With deadlines looming, Isro began exploring international options to procure the technology. At the time, only the United States, Japan, countries in the European Union, and Russia had developed a working cryogenic engine.

Offers came in from the United States and the European Union, but both were very expensive and came without the transfer of technology.

Then came Russia’s Glavkosmos.

In 1990, it proposed a far more favourable deal: two cryogenic engines along with full transfer of technology. For Isro, it was a breakthrough. The deal was signed, and a team of eight Indian scientists was sent to Moscow to begin training and joint development.

US BLOCKS INDIA

Fifteen months after the deal was signed, the United States objected, claiming that the agreement violated the Missile Technology Control Regime (MTCR), and imposed sanctions. The West feared that India could repurpose cryogenic technology to develop long-range ballistic missiles.

Under mounting international pressure, Glavkosmos withdrew from the deal in 1993. In its place came a heavily revised agreement that allowed the delivery of seven fully assembled cryogenic engines—but with no transfer of technology.

Around the same time, the government sanctioned a Rs 300 crore initiative to develop an indigenous cryogenic engine. The man appointed to lead this project was Nambi Narayanan.

Narayanan had joined Isro in 1966 as a technical assistant at the Thumba Equatorial Rocket Launching Station. In 1969, he was sent to Princeton University on a Government of India scholarship, where he specialised in chemical rocket propulsion. During the 1970s, when Isro relied solely on solid-fuel technology, Narayanan played a pivotal role in introducing liquid propulsion to India.

He led the development of the Vikas engine, which went on to become a crucial component in both PSLV and GSLV missions. Now leading the cryogenic engine programme, Narayanan saw it as a mission to make India self-reliant in space. But he had no idea that this mission—and his life—were about to be torn apart by a conspiracy.

As the cryogenic project picked up momentum, an unexpected storm hit. In late 1994, Nambi Narayanan and his colleague Sasi Kumaran were suddenly arrested on charges of espionage. They were accused of leaking confidential data to Pakistan through two Maldivian women, who Narayanan had never met.

The case stunned the nation. Narayanan was subjected to brutal interrogation. The cryogenic engine programme, already under strain, suffered a setback. Morale within Isro dropped, and one of its finest engineers was vilified without cause.

Eventually, the case was transferred to the Central Bureau of Investigation (CBI), which found no evidence to support the charges. Narayanan was acquitted. Years later, on September 14, 2018, the Supreme Court acknowledged the grave injustice he had suffered.

NEVER GIVING UP

Despite the fallout, Isro did not give up, and neither did Nambi stop fighting the battle for justice.

The early 2000s saw multiple GSLV test flights fail. Engines misfired. Rockets underperformed. Entire missions were lost. Western media often mocked India’s ambitions, painting them as unrealistic and overreaching.

But India persisted.

The breakthrough came on January 5, 2014. Isro successfully launched the GSLV-D5 mission using a 100% indigenous cryogenic upper stage. It was more than a technological milestone; it was a declaration to the world. Today, that very engine—once denied, sabotaged, and born out of adversity—has placed the world’s most advanced Earth observation satellite into orbit.

For Nambi Narayanan, this mission stands as a quiet redemption. The rocket that once slowed under the shadow of false accusations now carries international payloads into space. The man once labelled a traitor is now honoured as a pioneer of India’s space self-reliance.

(This is an authored article by Srijan Pal Singh. He is an author and an IIM Ahmedabad graduate, who was the Advisor for Policy and Technology to Dr. APJ Abdul Kalam, 11th President of India.)

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