As India prepares to send astronauts into space under the Gaganyaan programme, a critical but largely invisible process has come into focus — human-rating. While India’s LVM-3 rocket has already demonstrated reliability in launching satellites, flying humans requires a fundamentally different safety philosophy, engineering depth, and tolerance for failure.
What does human-rating actually mean?
Human-rating is the exhaustive engineering, testing, and certification process that ensures a space system can safely carry humans. Unlike cargo missions, where some risk is acceptable, human-rated systems are designed to keep the probability of crew loss extremely low.
According to NASA’s benchmark standards, an acceptable risk level is roughly a 0.2% chance of catastrophic loss of crew during the most dangerous phases of flight — ascent and descent.
To achieve this, human-rating typically requires:
- Multiple layers of redundancy in critical systems, such as triple or quadruple flight computers.
- Robust abort systems, including a crew escape system active throughout ascent.
- Fault tolerance against single-point failures.
- Reliable environmental control and life-support systems.
- Far more extensive testing, verification, and documentation than cargo rockets.
Why is human-rating so difficult?
Reaching orbit is one of the harshest engineering challenges humans attempt. Rockets must accelerate to nearly 28,000 kmph in just 8–10 minutes, while enduring intense vibrations, extreme temperatures, and maximum aerodynamic stress.
This environment is far less forgiving than aviation. Commercial aircraft fly at under 1,000 kmph, operate within the atmosphere, have large safety margins, and can divert or glide during emergencies. As a result:
- Even the most reliable orbital launch vehicles achieve success rates of about 98–99.5%.
- Commercial aviation, by contrast, records roughly one fatal accident per 10–20 million flights.
Human-rating therefore aims not at perfection, but at systematically managing unavoidable risk.
Which launch vehicles are currently human-rated?
At present, only a handful of launch systems regularly fly humans to orbit:
- Russia’s Soyuz-2
- China’s Long March 2F
- SpaceX’s Falcon 9 (with Crew Dragon)
In the United States, ULA’s Atlas V completed a crewed test flight with Boeing’s Starliner in 2024 but awaits full operational certification. NASA’s Space Launch System (SLS) is human-rated, though it has so far flown only one uncrewed mission (Artemis I) and is preparing for its first crewed flight.
Who certifies human-rated launch vehicles?
Certification frameworks differ by country:
- In the U.S., NASA grants final human-rating certification for missions involving its astronauts.
- The FAA licenses commercial launches to protect public safety on the ground, not crew safety.
- China’s human-rating approvals are granted by the China Manned Space Agency (CMSA).
- Russia’s Roscosmos certifies the Soyuz system.
Human-rating is thus not a commercial label but a sovereign safety decision.
How successful have human-rated systems been?
Historical data underscores both success and inherent risk:
- The Soyuz programme has flown over 150 crewed missions since 1967, with a success rate near 98%. After early tragedies in 1967 and 1971, it has delivered crews safely for decades.
- The U.S. Space Shuttle flew 135 missions between 1981 and 2011, with two fatal failures — Challenger (1986) and Columbia (2003).
- SpaceX’s Falcon 9 with Crew Dragon has achieved a 100% success rate across 20 human spaceflights so far.
- China’s Shenzhou programme has completed 16 crewed missions since 2003, though a recent mission saw capsule damage from space debris, highlighting emerging orbital risks.
Why aren’t all rockets human-rated?
Human-rating is expensive and technically demanding. It adds mass, complexity, and cost, and can even introduce new failure modes. For cargo missions, the goal is simple: deliver maximum payload to orbit at minimum cost.
Adding human-rated redundancies for satellites or supplies would:
- Reduce payload capacity.
- Increase launch costs.
- Make commercial missions less competitive.
Hence, most rockets are optimised for cargo, not crew.
LVM-3 and India’s path to human spaceflight
India’s Gaganyaan mission will rely on the LVM-3 rocket, which ISRO is currently certifying for human-rating. Once approved, it will be redesignated as HLVM-3.
To meet crew safety requirements, ISRO has:
- Added multiple backup and redundant systems.
- Improved reliability of engines and subsystems.
- Developed and tested a high-speed crew escape system.
- Undertaken extensive validation well beyond normal launch standards.
The LVM-3 was chosen because it has already completed seven consecutive successful orbital missions, including Chandrayaan-3, and uses fully indigenous propulsion systems — aligning with India’s Atmanirbhar Bharat vision in strategic technologies.
What to note for Prelims?
- Human-rating ensures acceptable risk for crewed spaceflight.
- NASA’s benchmark loss-of-crew probability: ~0.2%.
- Only a few launch vehicles globally are human-rated.
- LVM-3 will become HLVM-3 after certification.
- Crew escape systems are central to human-rating.
What to note for Mains?
- Explain why human spaceflight demands a different risk framework than satellite launches.
- Discuss the technological and economic trade-offs of human-rating.
- Analyse Gaganyaan’s significance for strategic autonomy and technological capability.
- Examine emerging risks like space debris for future human missions.
