Ministry of Earth Sciences Locates and Recovers GSLV subsystems

Union Minister for Science & Technology and Earth Sciences, Shri Kapil Sibal said at a Press Conference in New Delhi today revealed that the Ministry of Earth Sciences has successfully recovered some of the debri of GSLV from the sea floor. The team was able to recover three of the four engines i.e S-1, S-2 and S-3 and large debri from S-4 stage. He expressed hope that the recovery will enable ISRO to analyse the data and physically verify the debri to reach the conclusion a as to why the launche failed. The Minister further said that this is only the second recovery in the history of space programme .

At the request of the Department of Space (DOS), Secretary, Ministry of Earth Sciences (MoES) agreed to take up the mission of location and possible recovery of GSLV subsystems, the rocket that failed on 10th July, 2006 off Sriharikota and the debri was noticed falling into the nearby sea (Bay of Bengal). The MoES taken up the national mission through its autonomous institutions, National Centre for Antarctica and Ocean Research (NCAOR), Goa and National Institute of Ocean Technology (NIOT), Chennai. A team was mobilized from Chennai on 15th July to begin the sonar surveys based on the four impact predicted points provided by the ISRO and the location accuracy was defined at +/- 300 m. The four points represent the four L40 strap-on engines, one of which was a failure engine that caused the mishap.

Four ships of MoES, i.e., ORV Sagar Kanya, CRV Sagar Purvi, CRV Sagar Paschimi and a chartered vessel, Akademik Boris Petrov were pressed into operation as per requirement both for sonar surveys, diving operations and recovery of the located sub-systems. The first sonar surveys around the four predicted impact points resulted in identification of a number of targets on the seafloor. An area of about 30 sq. km was covered. Physical verification of the seafloor for the identified targets and confirmation of the strap-on debri was taken up from 19th July by conducting diving operations in the area. A survey boat and two canoes were used as the platforms for diving operations including underwater videography. A professional diving team consisting of ten members was identified and the necessary gear to dive to the depths of up to 20 metres was mobilized. The first strap-on engine (S3) and the stage was located, the strewn engine components were gathered underwater by the divers and picked up by ORV Sagar Kanya on 20th July. The second strap-on engine and stage (S2) was located and recovered on 27th July. Both S3 and S2 were located within a radius of about a kilometer from the predicted impact points. Search was continued by diving in other target locations for the remaining two strap-on engines till end July.

Based on the recovery locations of S3 and S2, ISRO predicted new impact points for the remaining two strap-ons, i.e., S1 and S4. Emphasis was laid for the location of S4 engine that caused the failure of GSLV. The information on new impact points formed the basis for undertaking the Phase-II sonar surveys. An area of 6 sq.km was surveyed using CRV Sagar Purvi from 9th to 11th September and 18 locations were marked as the possible targets of debri. CRV Sagar Purvi and Sagar Paschimi were utilized from 19th to 27th September for diving and physical examination of the seafloor. Strap-on S1 stage was found to be disintegrated and strewn in an area of 0.5 kilometres and the S1-engine and stage related components were recovered on 24th September. The search continued and all the 18 locations were searched during the Phase-II.

Considering the recovery of three strap-ons (S1, S2 and S3) and based on their relative recovery locations, ISRO reevaluated their data to predict the impact point of S4. A large area of 92 sq km was defined for high resolution sonar surveys where about 600 line km of data was collected. The sonar surveys in Phase-III began on 8th October onboard CRV Sagar Paschimi and completed on 13th September. A number of new possible targets of debris were demarcated. Diving was carried out from 12th to 21st October specifically aimed to locate S4 engine, leaving the areas where the core vehicle likely to have been disintegrated. The components of S4 stage were recovered at a number of locations. The major recovery was the S4 nose cone, middle parts of the stage and base plate electronics etc. There was very little clue on the S4 engine and the related components. In a search of about 1 kilometre radius from the S4 nose cone recovery location, melted, twisted and broken metallic pieces of S4 lower stage parts were recovered. The prediction of S4 total disintegration may offer a possible explanation for the non-recovery of S4 engine unlike other three recovered.

The diving was difficult in the area due to underwater currents, poor visibility and the disturbance of the seabed due to intense fishing activity. Natural features like sand bars, ripples, anchor and dredge marks on the seafloor were physically distinguished and eliminated from the targets of rocket debri by the visual inspection of the divers. Radial search upto 150 m around the potential targets and systematic grid search methods were employed from Sunrise to Sunset. About 550 diving operations were done during the campaign that lasted for nearly 100 days overall. Remotely Operated Vehicle (ROV) was used in a limited area during the nights due to depth and visibility limitations.

GSLV debri recovery from sea is perhaps the only second such attempt in the world. The European Space Agency (ESA) reported the failure of their maiden test flight of Ariane 5 in which the original four Cluster spacecraft were destroyed on 4 June 1996. It was reported that only about 40 seconds after initiation of the flight sequence, at an altitude of about 3.7 km, the launcher veered off its flight path, broke up and exploded. All the launcher debris fell back onto the ground and scattered over an area of approximately 12 sq km. In contrast the GSLV lasted for about a minute, reached an altitude of about 11 km and disintegrated and the debri strewn over an area of approximately 60 sq km. The GSLV debri found nearest to the launch pad is at a radial distance of 6.3 km (S4-Nose Cone) towards sea and the farthest point is about 7.5 km (S3 engine).

ESA reported that “Recovery of material proved difficult, however, since this area is nearly all mangrove swamp or savanna. Nevertheless, it was possible to retrieve from the debris the two Inertial Reference Systems. The results of the examination of this unit were very helpful to the analysis of the failure sequence”.

Source : Press Information Bureau
Date : November 06, 2006