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Human spaceflight and space stations
Human spaceflight: India's crewed programme and its test flights, space stations, astronauts on foreign missions, and keeping a crew alive in orbit and bringing it home. Prelims has asked about Gaganyaan and other microgravity missions.
UPSC has asked
- Prelims 2025: Axiom-4, SpaDeX and Gaganyaan as microgravity missions
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Gaganyaan
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Gaganyaan is the first human spaceflight programme of the Indian Space Research Organisation (ISRO), and it will carry a crew module to low Earth orbit and bring it back. The programme is being proved in stages, and each test clears one of the things that can kill a crew.
- The first uncrewed flight, carrying the half humanoid Vyommitra, is targeted for the last quarter of 2026, with two more uncrewed flights and the first crewed flight by 2027.
- The crew escape test TV-D1 and two parachute air drop tests are done, and TV-D2 is in progress.
- Every stage of the human-rated LVM3 (Launch Vehicle Mark-3) has been ground tested.
What changed
21 Aug 2026
The Hindu, 21 Aug 2026: How Gaganyaan's heat shield will protect the crew (opens in a new tab)
30 Jul 2026Update
- The government approved indigenous development of four items now bought abroad: the flight suit, the view port, the crew seat and the docking system.
- The baseline design review of BAS-01, the first of five modules of the Bharatiya Antariksh Station, is complete. BAS-01 is to fly by 2028 and the full station by 2035.
PIB, 30 Jul 2026: PARLIAMENT QUESTION: HUMAN SPACEFLIGHT AND INDIGENOUS SPACE TECHNOLOGY (opens in a new tab) · PIB, 29 Jul 2026: PARLIAMENT QUESTION: GAGANYAAN PROGRAMME (opens in a new tab)
12 Jul 2026Update
- ISRO completed the first ground test of SOLVE, a solid motor vehicle built to lift the crew module to 10 to 17 km so that the full parachute sequence can be tested, and cleared tests of the system that keeps the module upright after splashdown.
- The crew module is a sphere and cone shape: the blunt base throws a detached shock wave that keeps heat away, while the cone gives the lift and stability a sphere lacks.
Background reading: PIB, 5 Aug 2026: Gaganyaan timeline and Bharatiya Antariksh Station (opens in a new tab)
Re-entry heat shielding
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Coming home is the most demanding part of the flight, 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, which does not resist the heat so much as spend itself on it.
- Its outer layers char, decompose and burn away, carrying the absorbed heat off with them.
- The gases escaping from the surface form a cooler boundary layer that holds the hottest gas away from the wall.
- Because the material is consumed, an ablative shield 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
Radiation shielding for a crew
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Away from the shelter of the Earth's magnetic field, a crew takes whatever the Sun sends, and an eruption during a long mission is the case that has to be planned for. Shielding has to stop charged particles without adding weight a rocket cannot lift.
- Weight for weight, hydrogen rich polymers stop protons better than lead, because a hydrogen nucleus is a single proton.
- AstroRad, a vest of such material made by Israel's StemRad, was shown to cut the dose a crew would take in a solar storm.
- It flew uncrewed on Artemis I, a Moon mission of the National Aeronautics and Space Administration (NASA).
- The modelled dose fell by about 60 per cent for the August 1972 storm and about 40 per cent for October 1989.
- Such shielding holds off the charged particles of a solar storm but not galactic cosmic rays.