Spaceport of India - ISRO’s Launch Facility at Sriharikota
SDSC is a strategically important establishment of ISRO where PSLV and GSLV based launch vehicles are assembled and launched. The center also caters to the preparation of solid propellant stage for the launch vehicles. The center has two launch pads to cater to rocket launching operations supported by a world class mission control center. It has the necessary infrastructure for launching satellites into the low earth, polar and geostationary transfer orbits. The launch complexes provide complete support for vehicle assembly, fueling, checkout and launch operations. Apart from these, it also has facilities for launching sounding rockets meant for studying the earth's atmosphere. The center has gained importance in recent times as ISRO has started providing services to other countries. ISRO has until now launched over 50 satellite into space, both for domestic and international clients. The success of this center is elucidated by the heavy demand that this facility has witnessed. The launch frequency has doubled up in 4-5 years from one in 40 days to one in 20 days. The facility is launching one vehicle every month on an average. This has led to pressure on resources and the two launch pads are now almost always under operations with limited downtime available post-launch. The demand is so high that the operation cannot even rest during rains and specially designed campus allows super-quick drainage of water. The facility has its own metrological department to monitor weather conditions. The campus houses many observation decks to monitor launch operations. There is also the deepest penetrating radar of India called Mobile Object Tracking Radar – MOTR. This has over 100 kilometers of range and ensures that the path of the launch vehicle is clear from disturbances.
Immediately after breakfast, we proceeded to our first point of interest – The First Launch Pad. The design of this launchpad is based on a concept of Mobile Service Tower (MST) where the assembly building is a movable tower which travels on special rails and places itself next to the launch vehicle during its assembly. Heavy motors are used for the movement of MST over the 200-meter track. The 3450-ton building moves at a speed of about 7 meters per minute on a support of 8 wheels supporting 4 bogies. The integration and assembly of the launch vehicle are a time-consuming affair and hence, the MST is designed to protect the launch vehicle during the entire process. The design, made in 1980, provides this 76-meter building with 16 fixed platforms and large protective doors allowing it to cover the launch vehicle during assembly. We visited the launch pedestal which has centrally located angular structure used to hold the rocket. The steel structure is refurbished with silicon based rubber insulation as bare steel with melting temperature of 1500 Degree Celsius cannot withstand launch flame of 3000 Degree Celsius. The insulation has been designed in-house by ISRO’s chemical engineers. As soon as the launch is complete, water jets are used to cool the platform to prevent any long term damage to the structure. All the equipment used within the MST is flameproof including a landline phone device which costs over 1.5 Lakh. The entire assembly crew is required to wear special clothing, when on work. Additionally, there are four 120 meter high lightning towers to protect the vehicle from any damage during thunderstorms. There is a mobile tower located at about 100 meters from the MST to facilitate communication during assembly. This is an ambulatory tower and is relocated during launches. During a launch, 4 hours prior to actual launch time (T-4), complete evacuation from the launch pad (LP) area is ensured to prevent any loss of life. This launch pad is specially designed for four stage PSLV launches. The design of four stage PSLV includes a satellite on top with a solid propellant stage below it, which takes 105 seconds to burn. The satellites are manufactured/assembled at ISRO’s Bangalore facility while the first stage is prepared at SHAR facility itself. The next stage is of liquid propellant, filled in after assembly during countdown because of its hazardous nature. There is a mechanism which separates each stage once the fuel of the stage is exhausted, based on height achieved by the vehicle. The liquid stage comes from Mahendragiri in Tamil Nadu, a small city near Kanyakumari.
After covering the First Launch Pad, we proceeded towards the Second Launch Pad which is an engineering marvel in itself. This launch pad was dedicated to the nation by the Missile Man – Dr. Kalam himself. It is different from the first one in its basic design itself. At the first launch pad, the vehicle assembly building moves to the assembly and umbilical tower where the vehicle remains fixed. However, at the second launch pad, the assembly building is fixed and the vehicle moves on a mobile platform. We had the pleasure of witnessing a live assembly during our trip. There are specially designed bogies where the assembly of the entire launch vehicle takes place. The base structure is placed on the bogie and it is then moved into the assembly building through huge gates. Here, the entire assembly of the vehicle takes place where the fuel units and other components are put together to complete the vehicle. The assembly building is about 100 m high and assembles the launch vehicle of about 40 m height. All the assembly takes place while the vehicle is mounted on the bogie. There are platforms at various levels in the assembly building which can be vertically moved to adjust according to requirements. This is another difference from the first launch pad where the platform levels were fixed. Once the assembly is completed, the bogie takes the vehicle to the umbilical tower or UL where it is readied for launch. While we were there, the crew was busy preparing a PSLV for launch. This particular vehicle was developed by Mencken for ISRO and was designed to place the fifth IRNSS satellite in space. This would strengthen the capability of our in-house GPS system – Read More at . Once the entire assembly is completed the vehicle is moved to the launch area and set up within the umbilical tower. The Mobile Launch Pad or MLP is used for the purpose.
Once we completed our tour of the assembly building for 2nd Launch Pad, we went ahead to explore the launch facility. The platform is capable to launch both GSLV and PSLV based vehicles. An elevator takes you to a height of 18 meters where metaled platforms provide an exciting site to base on. The entire view consists of machinery and wires and tubes. There are four umbilical towers that run in to feed the vehicle with necessary inputs – Propellant (which includes fuel and oxidizer), Gas (through motor turbine operations to generate pressure for ignition), cooling agent and electronic connections. There is a special water storage to support the acoustic suppression mechanism. Another ride in the elevator takes you to 70-meters height, which is the crane level – a 10-ton crane is based on this level.
Next spot on our tour of this marvelous ISRO facility was a plant shaped building built strategically to allow a clear line of sight view of the launch pads, which are about 5 kilometers from here. This building is nerve center of operations related to any satellite launch and is connected to both the launch pads through communication links which are protected by heavy concrete structures, designed to withstand launch impact. It houses Launch Control Center (LCC) and Mission Control Center (MCC). LCC handles the initial preparation and facilitation of launch and controls fueling, testing and verification of the launch vehicle. Once the vehicle is ready for launch and has been fueled in, control is transferred to the MCC. MCC is responsible for managing the launch and flight path until 25 minutes post launch. Directors sit in the last row of the center with the exception of the TTC director who sits a row ahead wand is charged with the responsibility to monitor weather and telemetry. ISRO has established multiple monitoring stations around the world to capture real-time weather and other relevant parameters and avoid communication delays. The SHAR center also has its own metrological unit which givers real-time weather updates. Prelaunch special balloons with sensors are sent into the atmosphere to gather temperature, wind speed and other weather parameters to assess if weather conditions are apt for a launch.
The countdown starts 50 hours before a launch (T-50hr). This is the time when LCC springs into action and begins preparation of vehicle for launch. An hour before the launch (T-1hr) the control of the vehicle is transferred to the MCC where a well-choreographed process manages the launch operations. A half hour before the launch (T-1/2 hour), a readiness signal is given out by 6 radars spread throughout the campus. Once everything is apt for the launch, final launch authorization is given at T-17min post which an automated sequence of events take place. Post authorization, the entire module is handled by computers powered by artificial intelligence. Once the launch is successful and the vehicle maintains the correct path for 25 minutes, the control is transferred to Satellite Control Center (SCC) in Bangalore where the satellite is monitored continuously. Once the launch is over the launch area is kept out of bounds based on the launch platform. For GSLVs, the crew is allowed in launch arm only after a day while for PSLVs, the security team analyzes the pollution level from one hour after launch and crew is only allowed in once the pollution dips past the acceptable levels.
One would assume that this definitely is a critical facility for strategic interests for India and hence security provisions for SHAR center need to be top-notch. CISF has the responsibility of securing the campus from the very start. Current strength of security personnel is 1000 and there are over 12 watch towers across campus for CISF to monitor the area. Night and day specific binoculars and goggles are used by the personnel. Security personnel are sourced from across the country to prevent collusion and sabotage. Special surveillance equipment to monitor any breach through surrounding waterbodies have been set up. The location itself has been chosen strategically as an island is dedicated to ISRO operations and no unauthorized person is allowed. Shores are easier to monitor than land and hence the island.