How reusability can lead to sustainable, cost-effective access to space
How efficiently can rockets launch payloads or crew?
Human space missions are 3-5-times more expensive than satellite missions because of the more complex requirements for life support, safety, redundancy, and mission planning. These systems require higher investment in technology and infrastructure compared to uncrewed satellite missions. In contrast, most satellite missions are one-way trips built with comparatively simpler hardware/software architectures.
Rockets have to face two major hurdles on their way to orbit through the atmosphere: gravity and aerodynamic drag. To move forward, the rocket has nothing to push against; hence, it must eject engine exhaust backward in a supersonic jet.
The Tsiolkovsky rocket equation connects how fast a rocket can go to the amount of fuel it burns and how much it weighs. It shows that space travel has a weight problem: because fuel is so heavy, the rocket needs more fuel just to lift the first load of fuel. This creates a cycle where over 90% of a rocket’s mass is dedicated to propellant and tankages, leaving less than 4% for the actual satellite.
Why do rockets have stages?
Staging splits a rocket into independent propulsion units that are discarded sequentially to shed dead weight. It’s an engineering trick used to beat the ‘trap’ of the Tsiolkovsky equation by discarding spent stages in-flight so that the propellant-to-mass fraction of the remaining vehicle improves. In traditional expendable rockets, including PSLV and LVM-3, each stage is used once and thrown away, usually falling into the ocean.
The private company SpaceX brought in many path-breaking technologies, including 3D printing rocket parts, modular design, making most parts in-house (called vertical integration), and reusing rocket stages. Together they have cut costs sharply and increased launch frequency.
Reusability is widely considered the single most significant game-changer for human access to space, fundamentally shifting the industry from a ‘disposable’ model to a ‘transportation’ model. The SpaceX Falcon 9 rocket’s first stage comes back to the earth using a mix of smart engineering and automation. Here, the stage fires its engines to slow down as it nears the ground, removing most of its kinetic energy. The remainder is dissipated by the aerodynamic drag during its journey through the air.
SpaceX has successfully recovered the first stages of its Falcon 9 rockets more than 520 times. It’s currently developing its next generation multi-purpose rocket, Starship, as a fully reusable vehicle with a more efficient architecture. It has enough power to carry crew and cargo to the earth’s orbit, the moon, and even Mars.
Worldwide there are more than a dozen private companies and start-ups actively developing reusable rocket technology. At least three of them are working on the more challenging fully-reusable rocket technology. Washington-based Blue Origin has successfully demonstrated recovery of the booster for its New Glenn vehicle via vertical landing. The commercial space sector in China is also rapidly advancing, with companies like LandSpace recently attempting to recover parts of its orbital-class Zhuque 3 rocket.
Can a stage be reused multiple times?
The number of times a recovered rocket stage can be used is limited primarily by structural and material fatigue, especially in the main engines and fuel tanks.
The extreme temperature swings from cryogenic propellants to combustion heat, combined with immense pressure and g-force cycling during ascent and re-entry, cause fatigue and microfractures. The practical limit is also set by refurbishment economics and acceptable risk. As the number of flights increase, the cost and time required for rigorous inspection, testing, and replacement of vulnerable components, to maintain high reliability, will eventually outweigh the cost savings compared to building a new stage. SpaceX has been known to reuse the first stage more than 30 times for launch missions.
Where does India stand?
The Indian Space Research Organisation (ISRO) has been working on different models of recovery technologies. One option is the Reusable Launch Vehicle (RLV), a winged spacecraft, like a mini shuttle, that can be launched to space on a rocket and then made to re-enter to land on a runway. The other option is recovering the spent first stage of a rocket with a combination of aerodynamic drag and retro-propulsion to land on a barge or land. Technology development activities are progressing in these domains.
In order to be competitive in a rapidly emerging space market where fully reusable launch vehicles are about to be a usual feature, the need of the hour is inducting disruptive technologies that will lower the cost of accessing space. Therefore, future launch vehicles should target configurations with a minimum number of stages with partial or full recovery and with reuse of stages as a non-negotiable design driver.
Today, advances in propellant density and engine efficiency allow two-stage systems to perform missions that previously required three or more stages. A careful balancing of the energy delivered by each stage, its cost share, innovative technologies for high performance, compact engine development, recovery of stages, and refurbishment for increasing launch cadence are some of the aspects to be seriously addressed while designing any future launch vehicle.
Unnikrishnan Nair S. is former director, VSSC and IIST; founding director, HSFC; and an expert in launch vehicle systems, orbital re-entry, and human spaceflight technologies.
Published – January 21, 2026 08:30 am IST
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