Gaganyaan’s Thermal Protection System (TPS): How ISRO Protects Astronauts

22 Aug 2026

Subject: GS 03: Science and Technology

Context: ISRO’s Gaganyaan programme is preparing for its first uncrewed test flight.

This has brought renewed focus on the module’s Thermal Protection System (TPS) — the technology that keeps astronauts safe from re-entry heat.

About Gaganyaan Mission

Gaganyaan is India’s first human spaceflight mission, aimed at demonstrating the capability to send a three-member Indian crew into Low Earth Orbit (LEO) and safely return them to Earth.
Launch: The programme was announced in 2018 and is being implemented by ISRO.
Mission Profile: The mission will place astronauts in an orbit of about 400 km for up to three days, followed by a safe splashdown in the sea.
Objective: To develop indigenous capabilities in human spaceflight, including crew safety, life support systems, crew escape systems, re-entry technologies, and recovery operations.

During re-entry, the Gaganyaan crew module will enter Earth’s atmosphere at around 7,500–8,000 m/s.
More than 99% of its kinetic energy is converted into heat during atmospheric deceleration.
External surfaces may experience temperatures of up to 1,800°C.
The TPS, despite being only around 30–35 mm thick, must keep the crew module’s internal temperature below 150°C.

Type	How it protects	Key feature
Ablative TPS	Material decomposes and carries heat away	Mostly suited to single-use spacecraft
Radiative TPS	Absorbed heat is emitted back as radiation	Suitable for reusable vehicles
Heat Sink TPS	Material absorbs heat while remaining solid	Relies on high heat capacity

Astronaut Safety: Protects the crew from extreme re-entry temperatures.
Indigenous Capability: Strengthens India’s expertise in human-rated spacecraft and re-entry technologies.
Future Human Spaceflight: Provides a technological foundation for sustained Indian human-spaceflight missions.
Reusable Technologies: Knowledge gained from TPS development can contribute to future spacecraft and reusable launch systems.

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