The Space Capsule Recovery Experiment (SCRE or more commonly SRE or SRE-1) is an Indian experimental

spacecraft A spacecraft is a vehicle or machine designed to spaceflight, fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth ...

which was launched at 03:53 UTC on January 10, 2007, from

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by the

Indian Space Research Organisation The Indian Space Research Organisation (ISRO; ) is the national space agency of India, headquartered in Bengaluru. It operates under the Department of Space (DOS) which is directly overseen by the Prime Minister of India, while the Chairman of ...

(ISRO). The launch was conducted using the C7 launch of the

PSLV The Polar Satellite Launch Vehicle (PSLV) is an expendable medium-lift launch vehicle designed and operated by the Indian Space Research Organisation (ISRO). It was developed to allow India to launch its Indian Remote Sensing (IRS) satellites ...

rocket, along with three other satellites. It remained in orbit for 12 days before re-entering the Earth's atmosphere and splashing down into the

Bay of Bengal The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands of India. Its southern limit is a line bet ...

at 04:16 UTC on January 22.

Overview

SRE-1 was designed to demonstrate the capability to recover an orbiting space capsule, and the technology of an orbiting platform for performing experiments in

microgravity The term micro-g environment (also μg, often referred to by the term microgravity) is more or less synonymous with the terms '' weightlessness'' and ''zero-g'', but emphasising that g-forces are never exactly zero—just very small (on the ...

conditions. It was also intended to test reusable Thermal Protection System, navigation, guidance and control, hypersonic aero-thermodynamics, management of communication blackout, deceleration and flotation system and recovery operations. The information obtained from this technology and experiment is being applied to the design of India's ''

Gaganyaan Gaganyaan (Sanskrit IAST: ''gagan-yāna'', ) is an Indian crewed orbital spacecraft intended to be the formative spacecraft of the Indian Human Spaceflight Programme. The spacecraft is being designed to carry three people, and a planned upgrad ...

'' crewed orbital capsule.

Design

SRE-1 is a 555 kg capsule. It comprises aero-thermo structure, internal structure, Mission Management Unit, Altitude sensors and Inertial measurement unit, S-band transponder with unique belt array antenna embedded to ATS, power and electronics packages to support deceleration and flotation system. It also houses two microgravity payloads. It has a sphere-cone-flare configuration with a spherical nose of about 0.5 m radius, base diameter of 2 m and 1.6 m height. The parachute,

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devices,

avionics Avionics (a blend of ''aviation'' and ''electronics'') are the electronic systems used on aircraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fitt ...

packages of triggering unit and sequencer,

telemetry Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots ''tele'', "remote", and ' ...

and tracking system and sensors for measurement of system performance parameters are placed inside the SRE-1 capsule. Parachutes for SRE capsule were provided by

ADRDE ADRDE may refer to: * Air Defence Research and Development Establishment, a British Army radar research organization * Aerial Delivery Research and Development Establishment The Aerial Delivery Research and Development Establishment (ADRDE) is a ...

. To withstand the heat of re-entry, the cone-shaped SRE-1 has a Thermal protection system composed of 264 silica tiles of 14 different types over conical surface, and an ablative nose cap of carbon-phenolic composite. Scaled replica of SRE with this thermal protection system was validated in Plasma

Wind Tunnel Wind tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft ...

facility of CIRA, Italy. ISRO is also working on technology to manufacture carbon-carbon composite TPS, which, along with the silica tiles tested with the SRE-1, could find use in future reusable spacecraft such as ISRO's planned Reusable Launch Vehicle.

Re-entry

SRE-1 was traveling around the earth in a circular polar orbit at an altitude of 637 kilometers. In preparation for its reentry, SRE-1 was put into an elliptical orbit with a

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ell ...

of 485 kilometers and an

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any el ...

of 639 kilometers by issuing commands from the spacecraft control centre of ISTRAC at

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on January 19, 2007. The critical de-boost operations were executed from SCC,

supported by a network of ground stations at Bangalore,

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in Canada, Svalbard in Norway besides shipborne and airborne terminals. On 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 kilometers with a velocity of 8 km/s (ca. 29,000 km/h). During its reentry, the capsule was protected from the intense heat by carbon phenolic

ablative material Ablation ( la, ablatio – removal) is removal or destruction of something from an object by vaporization, chipping, erosive processes or by other means. Examples of ablative materials are described below, and include spacecraft material for a ...

and silica tiles on its outer surface. By the time SRE-1 descended to an altitude of 5 km, aerodynamic braking had considerably reduced its velocity to 101 m/s (364 km/h). Pilot and

drogue parachute A drogue parachute is a parachute designed for deployment from a rapidly-moving object. It can be used for various purposes, such as to decrease speed, to provide control and stability, or as a pilot parachute to deploy a larger parachute. ...

deployments helped in further reducing its velocity to 47 m/s (169 km/h).

Splashdown and recovery

The main parachute was deployed at about 2 km altitude. SRE-1 splashed down in the

with a velocity of 12 m/s (43 km/h) at 09:46 am IST (04:16 am UTC). The flotation system, which was immediately triggered, kept the capsule afloat. Recovery operations were supported and carried out by the

Indian Coast Guard The Indian Coast Guard (ICG) is a maritime law enforcement and search and rescue agency of India with jurisdiction over its territorial waters including its contiguous zone and exclusive economic zone. The Indian Coast Guard was formally estab ...

and

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using ships, aircraft and helicopters.

Experiments and results

During its stay in orbit, the following two experiments on board SRE-1 were successfully conducted under microgravity conditions. *One of the experiments studied metal melting and crystallisation under microgravity conditions. This experiment, jointly designed by the

Indian Institute of Science The Indian Institute of Science (IISc) is a public, deemed, research university for higher education and research in science, engineering, design, and management. It is located in Bengaluru, in the Indian state of Karnataka. The institute was ...

and

Vikram Sarabhai Space Centre The Vikram Sarabhai Space Centre (VSSC) is a major space research centre of the Indian Space Research Organisation (ISRO), focusing on rocket and space vehicles for India's satellite programme. It is located in Thiruvananthapuram, in the India ...

Thiruvananthapuram Thiruvananthapuram (; ), also known by its former name Trivandrum (), is the capital of the Indian state of Kerala. It is the most populous city in Kerala with a population of 957,730 as of 2011. The encompassing urban agglomeration populati ...

, was performed in an isothermal heating furnace. *The second experiment, jointly designed by National Metallurgical Laboratory,

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and ISRO Satellite Centre

, studied the synthesis of nano-crystals under microgravity conditions. This was an experiment in designing biomaterials that better replicate natural biological products. The experimental results have yet to be analysed. Performance of Silica TPS tiles in conical region of capsule was satisfactory and tile surfaces were found intact with some minor handling related damage during recovery operations. The spacecraft remained afloat for approximately 2 hours in seawater before recovery, causing minor cracks and seawater deposits on tile surfaces.

References

ISRO Presentation on Day 1 of the 14th annual meeting of the Asia Pacific Regional Space Agency Forum
{{Orbital launches in 2007 Satellites of India 2007 in India Spacecraft launched in 2007 Spacecraft which reentered in 2007 Test spaceflights Spacecraft launched by PSLV rockets