A returning capsule uses a heat shield and the thick air to shed its orbital speed, then opens parachutes in stages to settle gently onto the sea.
Coming home is the reverse of launch. A capsule in orbit moves at nearly 8 km/s. To land safely it must lose almost all of that speed. Slowing down with engines alone would need a great deal of propellant. Instead, capsules use the atmosphere as a brake.
During reentry the capsule dives into the upper atmosphere. Air piles up in front of it and slows it down, turning its speed into heat. A heat shield on the front protects the inside.
India first did this in January 2007. The Space Capsule Recovery Experiment, SRE-1, was launched on PSLV on 10 January, spent days in orbit, re-entered and was recovered from the Bay of Bengal on 22 January. Its planned splashdown zone was about 140 km east of the Sriharikota coast.
Once the capsule has slowed down in the thick lower air, parachutes take over. They open in stages, because one huge parachute opened at high speed would tear. ISRO's first Integrated Air Drop Test on 24 August 2025 dropped a dummy crew module of about 4.8 tonnes from about 3 km near Sriharikota. It used the same ten-parachute layout planned for Gaganyaan:
The main parachutes are let go after splashdown. The module was recovered and brought to Chennai port by INS Anvesha.
Gaganyaan's crew will come home by landing in Indian sea waters. In the TV-D1 test in 2023, the crew module was designed to touch the water at 8.5 m/s and float using buoyancy blocks, with sea markers and a location transmitter to help recovery teams find it.
Track the Gaganyaan test programme, including the parachute drop tests that prove the crew module can land safely. Follow Gaganyaan
How much energy must go. At 400 km, orbital speed is about 7.67 km/s, so the kinetic energy is ½v² ≈ 29.4 MJ per kilogram. A 4.8 t module carries about 4,800 × 29.4 MJ ≈ 141 GJ. Nearly all of this ends up as heat in the air around the capsule, which is why the heat shield matters so much.
Parachute physics. A falling body reaches terminal speed when drag balances weight:
m·g = ½·ρ·v²·Cd·A, so v = √(2·m·g / (ρ·Cd·A))
Check this against ISRO's IADT-01 numbers: m ≈ 4,800 kg, v ≈ 8 m/s, three main canopies of 25 m diameter. Total area A = 3 × π × 12.5² ≈ 1,473 m². Sea-level air density ρ ≈ 1.217 kg/m³ (NASA).
Solve for the drag coefficient:
Cd = 2·m·g / (ρ·v²·A) = (2 × 4,800 × 9.81) / (1.217 × 64 × 1,473) ≈ 94,180 / 114,700 ≈ 0.82
That is the drag coefficient ISRO's figures imply for the three canopies together.
Why so many parachutes. Drag grows with v². A 25 m canopy opened at a high speed would face loads it could not survive. Small drogues open first, at high speed, to slow the capsule. The big mains open only when the speed is low.
How hard is splashdown? An 8 m/s touchdown equals a free fall of v²/2g = 64 / 19.6 ≈ 3.3 m.
Drag force grows with the square of speed. Small drogues can survive opening at high speed and slow the capsule; the large main parachutes open only once the speed is low enough.
Two apex-cover separation parachutes, two drogues, three pilot parachutes and three main parachutes — ten in all.
India's Space Capsule Recovery Experiment, launched on PSLV on 10 January 2007; it re-entered and was recovered from the Bay of Bengal on 22 January 2007.