Space Capsule Recovery Experiment
Space Capsule Recovery Experiment (SRE) was a remarkable achievement in which ISRO successfully demonstrated the nation’s capability in bringing an orbiting capsule safely back on Earth and recovering it. SRE-1 weighing 555 kg, was launched on January 10, 2007, onboard PSLV-C7, along with the primary payload, CARTOSAT-2 and two other foreign satellites, LAPAN-TUBSAT and NANO-PEHUENSAT-1. The sphere-cone-flare shaped SRE-1 was put on the orbit on three axis stabilised sun pointing mode. It remained in the Polar Sun-Synchronous Orbit for 12 days, providing a platform for carrying out two microgravity experiments: ICO crystal growth Ga-Mg-Zn alloy (by Indian Institute of Science and VSSC) and Bio mimetic material synthesis of hydroxy aptite (by National Metallurgical Laboratory, Jamshedpur). Both these experiments were completed in three days between January 11 and 14.
After being in orbit for 12 days, on January 22, 2007, SRE-1 was de-boosted for re-entry under closed loop guidance, while the capsule was over the Pacific Ocean off the coast of Mexico. 900 s prior to the start of de-boost manoeuvre, the capsule was subjected to re-orientation based on time tagged command from the ground station. The de-boost phase lasted for 559 s. SRE-1 was speeding at 7.9 km/s at Mach 30 when its re-entry into the earth’s atmosphere took place over the Indian sub-continent at an altitude of 100 km.
The thermal protection system, consisting of carbon phenolic nose cap, reusable silica tiles in cone flare region and low density ablatives at flare end protected the internal packages from the high temperature, of the order of 7000 K, associated with the re-entry. The deceleration of the capsule to 12 m/s at splash down was achieved using a three stage parachute system. At 09 47 hours SRE-1 splashed into the Bay of Bengal, 140 km off the coast of Sriharikota.
The capsule was recovered using a Dornier aircraft and brought to main land onboard the Coastguard ship ‘Sarang’. The recovered capsule is displayed at the Space Museum at VSSC.