Successful splashdown for the SRE-1 capsule
24 Jan 2007
In a statement ISRO has said that the successful launch, in-orbit operation of on-board experiments and re-entry 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. According to ISRO, SRE-1 is an important beginning for providing a low cost platform for micro-gravity experiments in space science and technology and return of specimen from space.
Splashdown
According to ISRO, since its launch, the SRE-1 was going round the earth in a circular polar orbit at an altitude of 637 km. To facilitate its re-entry, the 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 through commands issued from the Spacecraft Control Centre (SCC) of ISTRAC at Bangalore on January 19, 2007.
Thereafter 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.
On Monday (January 22, 2007) morning, the re-orientation of the 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 re-oriented 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 re-entry, the capsule was protected from the intense heat by carbon phenolic ablative material and silica tiles on its outer surface.
According to the ISRO statement, 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, ISRO said, helped in further reducing its velocity to 47 m/sec (about 170 km per hour).
With the main parachute deployed at about 2 km altitude, the SRE-1 finally splashed down in the Bay of Bengal with a velocity of 12 m/sec (about 43 km per hour) at 09:46 am. The splashdown saw the flotation system immediately getting triggered, helping keep the capsule floating. The capsule was eventually recovered by the Indian Coast Guard and Indian Navy, which had deployed ships, aircraft and helicopters for the purpose.
Experiments in micro-gravity
Its orbital stay of 12 days, saw the SRE capsule successfully conducting two experiments under micro-gravity conditions. One of the two experiments, jointly designed by the Indian Institute of Science, Bangalore and Vikram Sarabhai Space Centre, Thiruvananthapuram, was related to the study of metal melting and crystallisation under micro-gravity conditions and 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. The experiment will be of use in designing better biomaterials having a close proximity with natural biological products.
ISRO says that experimental results will be analysed in due course by the principal scientific investigators of the two experiments.
The successful recovery of the SRE capsule from the waters of the Bay of Bengal should come as a shot in the arm for ISRO, helping it wipe off memories of a failed GSLV-F02 test in July last year.
