In the 1990s, the United States blocked India from acquiring cryogenic engine technology, invoking the Missile Technology Control Regime (MTCR). The intent was clear: keep India confined to Low Earth Orbit (LEO), away from the coveted Geosynchronous Earth Orbit (GEO) that underpins telecommunications, navigation, and high-value military applications. Three decades later, the NASA-ISRO Synthetic Aperture Radar (NISAR) satellite, a joint India-US mission, is set to fly aboard the GSLV Mk II powered by India’s own cryogenic engine. History has a sense of poetic justice, and this upcoming launch epitomises it.

The Science Behind The Politics: Understanding Specific Impulse

Rocket politics begins with a deceptively simple metric: specific impulse (Isp). Isp measures how efficiently a rocket engine uses propellant, expressed in seconds. The higher the Isp, the longer the engine can produce thrust per unit of fuel.

Consider two fuels:

Fuel B is twice as efficient. That efficiency gap defines whether a rocket can barely scrape LEO or carry heavy payloads to GEO and beyond.

ISRO’s early SLV rockets of the 1970s and 1980s used solid fuels like PBAN and HEF-20 with Isp values around 270 seconds, enough for LEO but far from the 460-second performance of Russian KVD-1 cryogenic engines. Cryogenics, using liquid hydrogen and oxygen at extremely low temperatures, offered that leap. Without it, India’s dreams of GEO satellites and deep-space missions were grounded.

The 1990s Technology Denial: A Calculated Strike

By the late 1980s,........

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