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.
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