Nisar mission: Once a denier of cryogenic tech, Nasa is now an Isro customer

India Today

3 days ago

On July 30, 2025, the Nasa-Isro Synthetic Aperture Radar (Nisar) satellite is set to lift off from the Satish Dhawan Space Centre in Sriharikota aboard India's GSLV rocket, powered by an indigenous cryogenic engine.This is the world's single most expensive civilian Earth imaging satellite. A collaboration between Nasa and Isro, the mission represents a major technological achievement and an even more significant geopolitical moment.advertisementNearly three decades ago, the United States actively blocked India's access to cryogenic engine technology. Sanctions were imposed, diplomatic pressure was applied, and international agreements were disrupted, all to keep India out of the elite club of space-faring nations. A LOOK BACK INTO PAST
It began in the early 1990s, a time when India's space programme was steadily gaining ground. By then, Isro had developed the Polar Satellite Launch Vehicle (PSLV), a dependable rocket that could carry satellites weighing up to 1,750 kilograms into low Earth orbit (LEO) at altitudes of around 600–800 kilometres.However, it had a crucial limitation: it could not lift heavier payloads into geostationary orbit (GEO), located about 36,000 kilometres above the Earth's surface. This is the orbit where most communication, weather, and broadcasting satellites operate.To reach that altitude with payloads typically weighing 2,000 to 2,500 kilograms or more, India needed a more powerful rocket and, more importantly, a more advanced engine.India needed a cryogenic engine.
Nisar satellite. (Photo: Nasa)
But cryogenic engines are extremely complex. Liquid hydrogen, the main fuel, must be stored at –253C, and liquid oxygen at –183C. Keeping these volatile substances stable inside a rocket, and then igniting them, demands precision engineering.The ultra-low temperatures can cause metal components to crack, valves to seize, and seals to fail. Most importantly, the entire system must function flawlessly under immense pressure and temperature during launch.A LIKELY DEPENDENCYIn the early 1990s, India did not possess this technology. Without it, India remained dependent on foreign rockets for critical space missions. To gain full independence in space, Isro had two options: develop the technology in-house or acquire it from abroad. Given the complexity and urgency, India first sought to acquire it.At the time, only a handful of countries, the United States, Russia, France, and Japan, had cryogenic capabilities.Japan was approached first, but negotiations failed to progress. Offers came from the United States and Europe. General Dynamics, an American firm, proposed a deal, as did Europe's Arianespace.
The cryogenic engine developed by Isro. (Photo: Isro)
However, both offers were expensive and included restrictive clauses that ruled out any transfer of technology. For India, which saw technology transfer as vital for long-term self-reliance, these deals offered little value.Then came a breakthrough. In January 1991, Isro signed a historic agreement with Russia's Glavkosmos to procure two cryogenic engines along with full technology transfer, for a relatively modest $200 million. The engines on offer, the RD-56 or KVD-1, had originally been developed for the Soviet manned moon mission.But that opportunity soon came under threat.SANCTIONS FOLLOWEDAs the Cold War ended and Russia turned toward the West for economic support, the United States began exerting diplomatic pressure. Under the Missile Technology Control Regime (MTCR), the United States claimed the engine transfer could aid missile development. In 1992, it imposed sanctions on both Isro and Glavkosmos, effectively blocking the deal.In its place came a heavily revised arrangement. It allowed the delivery of seven fully assembled engines, but with no accompanying blueprints, training, or transfer of technology. Adding to the humiliation, the agreement included a clause restricting India from using the engines only for peaceful purposes and prohibited any modification or re-export without Russian consent.advertisementThe irony was hard to ignore: this was the same technology the United States had earlier offered India, without objections, and at a much higher cost.These imported engines powered the early flights of the GSLV programme. But even as India used them, then Prime Minister P.V. Narasimha Rao recognised the strategic vulnerability of relying on foreign technology. In April 1994, the government launched an indigenous cryogenic engine development programme with an initial budget of 300 crore. The decision would lay the foundation for India's future self-reliance in heavy-lift launches.Despite the formal restrictions, cooperation between Russian and Indian scientists did not completely end. Many within Glavkosmos had developed deep respect for Isro engineers and discreetly supported their efforts.Sensitive components and technical inputs were quietly sent to India, sometimes through covert means. Ural Airlines, a Russian carrier, agreed to transport equipment discreetly in exchange for extra compensation. Many sources state that Nambi Narayanan, who headed Isro's cryogenic programme at the time, later confirmed that he personally accompanied some of these flights.advertisementBut these backchannel efforts were detected.As India pushed ahead with its indigenous programme, the United States appeared to shift tactics—from diplomatic pressure to disruption. In late 1994, Nambi Narayanan and his colleague Sasi Kumaran were suddenly arrested on false charges of espionage. They were accused of leaking confidential cryogenic engine data to Pakistan through two Maldivian women, whom Nambi Narayanan had never met.The case shocked the scientific community and the nation.Nambi Narayanan was subjected to brutal interrogation and intense media scrutiny. The cryogenic project came to a standstill. Eventually, the case was handed over to the CBI, which found no evidence of wrongdoing. Nambi was acquitted, and years later, on September 14, 2018, the Supreme Court acknowledged the injustice he had suffered.The scars of the espionage case did not stop Isro.SLOW AND STEADYProgress was slow and often marked by failure. Multiple test flights of the GSLV in the early 2000s faced setbacks. Engines underperformed, missions failed mid-flight, and questions were raised about whether India had taken on more than it could handle. And western media was in full glee at our struggles.advertisementThe breakthrough came on January 5, 2014, when Isro successfully launched the GSLV-D5 mission using a 100% indigenous cryogenic engine.It marked a turning point, not just for Isro, but for India's standing in the global space community. Since then, India has routinely used the GSLV for placing heavy satellites in orbit and has become a trusted launch partner for other nations.The same cryogenic engine that the world once refused to share has now become a symbol of India's resilience. And in a fitting turn of history, it is now all set to carry an American satellite into space. The deniers are now our customers.(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.)- EndsMust Watch