The Space capsule Recovery Experiment (SRE-1) launched by Polar Satellite Launch Vehicle (PSLV-C7) from Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota on January 10, 2007 was successfully recovered today (January 22, 2007) after being maneuvered to reenter the earth’s atmosphere and descend over Bay of Bengal about 140 km East of Sriharikota.
Since its launch, SRE-1 was going round the earth in a circular polar orbit at an altitude of 637 km. In preparation for its reentry, SRE-1 was put into an elliptical orbit with a perigee (nearest point to earth) of 485 km and an apogee (farthest point to earth) of 639 km by issuing commands from the Spacecraft Control Centre (SCC) of ISTRAC at Bangalore on January 19, 2007. The critical de-boost operations were executed from SCC, Bangalore supported by a network of ground stations at Bangalore, Lucknow, Mauritius, Sriharikota, Biak in Indonesia, Saskatoon in Canada, Svalbard in Norway besides shipborne and airborne terminals.
Today, January 22, 2007, the re-orientation of SRE-1 capsule for de-boost operations commenced at 08:42 am (IST). The de-boost started at 09:00 am with the firing of on-board rocket motors and the operations were completed at 09:10 am. At 09:17 am, SRE-1 capsule was reoriented for its re-entry into the dense atmosphere. The capsule made its re-entry at 09:37 am at an altitude of 100 km with a velocity of 8 km/sec (29,000 km per hour). During its reentry, the capsule was protected from the intense heat by carbon phenolic ablative material and silica tiles on its outer surface.
By the time SRE-1 descended to an altitude of 5 km, aerodynamic breaking had considerably reduced its velocity to 101 m/sec (363 km per hour). Pilot and drogue parachute deployments helped in further reducing its velocity to 47 m/sec (about 170 km per hour).
The main parachute was deployed at about 2 km altitude and finally, SRE-1 splashed down in the Bay of Bengal with a velocity of 12 m/sec (about 43 km per hour) at 09:46 am. The flotation system, which immediately got triggered, kept the capsule floating. Recovery operations were supported and carried out by the Indian Coast Guard and Indian Navy using ships, aircraft and helicopters.
During its stay in orbit for the last 12 days, the two experiments on board SRE-1 were successfully conducted under micro gravity conditions. One of the experiments was related to study of metal melting and crystallisation under micro gravity conditions. This experiment, jointly designed by the Indian Institute of Science, Bangalore and Vikram Sarabhai Space Centre, Thiruvananthapuram, was performed in an Isothermal Heating Furnace. The second experiment, designed by National Metallurgical Laboratory, Jamshedpur, was intended to study the synthesis of nano-crystals under micro gravity conditions. This experiment can help in designing better biomaterials having closest proximity with natural biological products. The experimental results will be analysed in due course by the principal scientific investigators of the two experiments.
The successful launch, in-orbit operation of the on board experiments and reentry and recovery of SRE-1 has demonstrated India’s capability in important technologies like aero-thermo structures, deceleration and flotation systems, navigation, guidance and control. SRE-1 is an important beginning for providing a low cost platform for micro-gravity experiments in space science and technology and return specimen from space.
