Satellite Transportation Systems (STS)
After celebrating 69th Independence Day, ISRO Satellite Centre (ISAC) had yet another eventful day on August 16, 2015, flagging off the nation’s prestigious and ISRO’s sought after satellite ASTROSAT, a mission for deep sky exploration. ASTROSAT was transported to the country’s spaceport at Satish Dawan Space Centre (SDSC), Sriharikota, using a specially designed Satellite Transportation System (STS). Team ISAC, apart from its responsibility in realising the state-of-the-art satellites, has been designing and developing world class STSs, Mechanical Ground Support Equipment (MGSE) and Mass Property Machines in-house and continuously striving to make them in India, tapping the potentials of Indian industry and realise them at remarkably competitive cost indigenously.
Here comes a brief story of satellite transportation, narrating about systems in place that make the successful shipment of satellites within India and abroad.
STS protects satellite against all environment hazards encountered during transportation. The STS is built with a suspension cradle that attenuates shock, vibration and handling loads. Double walled thermally insulated, sealed encapsulation structure of STS shields satellite from climatic hazards such as temperature, humidity, contamination, rain, dust, differential pressure, etc. Robust all metallic Faraday’s cage design and low resistance electrical bonding of STS provides Electro Static Discharge (ESD) path and protection against RF radiation hazards.
The present day STSs have emerged from a simple packaging technique started with a wooden crate to carry Engineering Model of India’s first satellite Aryabata and has progressively matured in technologies to the present STS comprising state-of-the-art protection systems, namely, Shock and Vibration Isolation System, Active / Passive Temperature and humidity Control, Pressure Equalisation and Rapid Decompression Protection during air shipment, Gaseous Nitrogen Purging for satellite / its subsystems / payload(s), Environmental Data Acquisition System, etc., along with integrally built handling and mobility devices, clean interiors, ESD protection wraps, corrosion resistant and aesthetic exteriors.
The latest design of STS is engineered in a modular way to carry satellites of different envelope dimensions (Diameter 3.05m or 3.65m or beyond) using exclusive replaceable encapsulation cover structures and a single common base that comprises all functional / protection devices. It is equipped with a Tilt Table that facilitates handling of tall satellites in vertical orientation at clean room and tilting it to horizontal transportation mode before closing the container cover. As against vertical mode of transportation, the horizontal mode meets the cargo cabin envelope dimensions in case of air shipment and also overcomes hurdles during road transportation such as height under the bridges, railway lines, electrical lines etc. Since mid 90s, horizontal mode of transportation has been adopted for air shipment of satellites abroad to launch destination at French Guyana. The environment around the satellite inside STS is continuously monitored and the data on shock and vibrations, temperature and humidity throughout the shipment are acquired, analysed and observed to be well within the safe limits which is also confirmed through post transportation checks on satellites.
System Integration Group (SIG), ISAC has the expertise in the design, development and realisation of STS for different class of satellites from conception to realisation, test and validation, and has successfully used a host of STS for satellite shipment. In addition, an Equipment Transportation System (ETS) is built to cater to the shipment of smaller satellites, multiple equipment panels, subsystems of satellites, etc. Apart from the standard features of STS, ETS has four built-in overhead hoists, modular suspension systems, and three way opening doors to suit varying interfaces. At present, design of new generation of large STSs (12.0m x 5.3m x 4.2m) for GSAT-11 and I6K (6000kg) class satellites on the anvil. These are to be handled under existing confined civil infrastructure / laboratories, limited crane capacity, constraints and compliance for air shipment using commercially available cargo aircraft.
These world class ground support systems required for satellite building are realised through Indian industry and ISRO has been nurturing and hand-holding them towards ‘the commitment to total quality and zero defects in space systems and services’.