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हिन्दी — Read in HindiHuman spaceflight and space stations
Gaganyaan and its test flights, the Bharatiya Antariksh Station, astronauts on foreign missions, and what it takes to keep a crew alive in orbit and bring it home. Prelims has asked about Gaganyaan and other microgravity missions.
Foundation note: Gaganyaan and the Bharatiya Antariksh Station
UPSC has asked
- Prelims 2025: Axiom-4, SpaDeX and Gaganyaan as microgravity missions
Showing 1 of 3 articles, those that changed from 1 to 31 August 2026.Show all
Re-entry heat shielding
Copy link to Re-entry heat shieldingPrelims and Mains
A heat shield is the thermal protection system that keeps a returning crew module from burning up, because the whole energy of orbit has to be shed as heat in a few minutes.
- The crew module meets the atmosphere at 7,500 to 8,000 metres a second, which takes its outside to about 1,800 °C while the structure beneath has to be held below 150 °C.
- Between the two is a thermal protection system 30 to 35 mm thick.
- The Gaganyaan module uses an ablative shield: its outer layers char, decompose and burn away, carrying the absorbed heat off with them, so it is used once.
Ablative
- The surface chars and burns away, taking the heat with it
- Single use
- Chosen for the Gaganyaan crew module
Radiative
- A hot outer skin radiates the heat back out
- Can be reused
- Needs materials that stay sound at high temperature
Heat sink
- A thick mass of metal soaks up the heat and holds it
- Heavy, so suited to small capsules
What changed
21 Aug 2026BriefThe Hindu set out the three kinds of thermal protection and why the Gaganyaan crew module uses a single use ablative shield. The Hindu, 21 Aug 2026: How Gaganyaan's heat shield will protect the crew (opens in a new tab)