The Problem with 'Dirty' Propellants
For decades, the workhorse of space agencies worldwide, including the Indian Space Research Organisation (ISRO), involved hypergolic propellants. These are chemical mixtures, like Unsymmetrical Dimethylhydrazine (UDMH) and Nitrogen Tetroxide (N2O4), that
ignite spontaneously on contact. While reliable, they are also highly toxic, carcinogenic, and difficult to handle. A launch isn't just about the spectacle; it involves managing hazardous materials that pose a significant environmental and health risk, both during manufacturing and potential launch failures. This traditional approach, while effective, carries a heavy legacy cost that the modern space era is keen to shed.
ISRO's New Recipe: Kerosene and Oxygen
ISRO's first major leap towards a greener future is the adoption of 'Kerolox'. This is a combination of liquid oxygen (LOX) as the oxidiser and a highly refined, aviation-grade kerosene as fuel. Known as ISROsene, this Indian-developed fuel powers the semi-cryogenic engines of rockets like the GSLV. The benefits are threefold. First, it’s significantly less toxic than UDMH, making it safer for personnel and the environment. Second, it's more cost-effective. Third, it offers a higher thrust, meaning it can lift heavier payloads into orbit. This switch isn't just an environmental upgrade; it's a strategic move that enhances ISRO's launch capability and commercial competitiveness in the global market.
The Future is Methane
The next frontier in green propulsion is methane, and India is already making strides. ISRO is actively developing engines powered by Liquid Oxygen (LOX) and Methane (CH4), often called 'methalox'. This combination is considered the holy grail for next-generation rockets. Methane is not only non-toxic but also burns cleanly, leaving behind no soot or residue. This is a game-changer for reusable engines, as it eliminates the need for extensive post-flight cleaning. Furthermore, methane can potentially be sourced or even manufactured on other celestial bodies like Mars (a process called in-situ resource utilisation), making it the ideal fuel for future deep-space and interplanetary missions.
The Ultimate Green: Reusability
The most effective way to reduce the environmental impact of spaceflight is to stop throwing rockets away after a single use. ISRO's Reusable Launch Vehicle (RLV) program is the cornerstone of this vision. The RLV-TD (Technology Demonstrator) has already completed several successful landing experiments, proving India's capability to develop the complex technologies required for a winged vehicle to fly back to Earth and land on a runway. A fully reusable rocket would drastically cut down on manufacturing waste and the cost per launch, making access to space more affordable and sustainable than ever before. This effort mirrors global trends led by companies like SpaceX, but with a uniquely Indian approach focused on methodical, cost-effective development.
Private Players Join the Green Race
This green transformation isn't limited to ISRO. India's burgeoning private space sector is building sustainability into its DNA from the ground up. Startups like Skyroot Aerospace and Agnikul Cosmos are designing their launch vehicles with green propellants in mind. For instance, Skyroot’s Vikram-1 rocket uses solid propulsion that is cleaner than traditional options, while Agnikul’s Agnibaan rocket is designed to fly with a kerolox-based engine. By prioritising these cleaner technologies, these private firms are not only aligning with global environmental standards but also positioning themselves as responsible and innovative players in the multi-billion dollar satellite launch market. This parallel innovation creates a robust, competitive, and sustainable national space ecosystem.
