India’s heavy rocket broke up midair on Christmas day when onboard connectors that transmit signals snapped inadvertently, the space agency said Friday.
“The inadvertent snapping of 10 connectors carrying command signals from the onboard computer to the control electronics of the four strap-on motors in the first stage is the primary cause of the rocket failure,” the state-run Indian Space Research Organsiation (ISRO) said in a statement here.
The connectors are located beneath the Russian-made cryogenic engine, which was in the upper/third stage of the 418-tonne geosynchronous satellite launch vehicle (GSLV-F06), carrying the 2.3-tonne GSAT-5P communication satellite.
The onboard computer resides in the equipment bay near the top of the rocket. The connectors were to separate on the issue of a separation command at 292 seconds (4.87 minutes) after the 51-metre tall rocket lifted-off at 4.04 p.m. Saturday.
The premature snapping of the connectors stopped the flow of control commands to the first stage control electronics and led to loss of control and break-up of the vehicle.
“The exact cause of snapping of the connectors, whether due to external forces like vibration, dynamic pressure is to be analysed and pin-pointed,” the space agency noted.
An ISRO official, however, told IANS earlier that the onboard computers relay commands through wires to other equipment in the three stages of the rocket.
“As the three stages separate one after another, it is inadvisable to have long wires connecting computers at the top and the stages located below. Hence we have connectors, sort of plugs and sockets, to relay the commands and peel off smoothly when the stages separate,” the official asserted.
According to former ISRO rocket scientist R.V. Perumal, connectors in a launch vehicle are akin to the vertebrae in a human being.
“Breaking of connectors is like cutting the vertebrae,” Perumal told IANS.
When the Rs.175 crore rocket was disintegrating within a minute after a smooth lift-off from spaceport Sriharikota in Andhra Pradesh, about 80km north-east of Chennai, a destruct command was given by the mission control centre to avoid its debris falling on the land though it was 8 km in sky and 2.5 km from the coastline over the Bay of Bengal.
“A destruct command was issued at 64 seconds after lift-off as per the range safety norms and the flight was terminated in the first stage itself,” the findings noted.
Soon after the mission failure, the space agency constituted a preliminary failure analysis team headed by former ISRO chairman G. Madhavan Nair to analyse the flight data.
The team included members of the launch authorization board, mission readiness review committee and senior project functionaries of the project.
The initial analysis found that though the rocket’s performance was normal up to 47.5 seconds from lift-off, it started developing problems in its orientation (attitude) leading to higher structural loads and breaking up six seconds later.
The Rs.125-crore heavy satellite onboard, with a payload of 36 transponders, including 24 in C-band and 12 in extended C-band, was intended to replace the ageing Insat-2E satellite that was launched in 1999, for communications, telecasting, weather and other related services.
ISRO Forms Eminent Panels to Study Failure
ISRO has constituted a committee to probe the unsuccessful GSLV-F06 mission and a panel to look into the future of the GSLV Programme and assured launch of satellites, operationalisation of indigenous cryogenic stage and strategy for meeting communication transponder needs.
ISRO Chairman K Radhakrishnan has formed a Failure Analysis Committee (FAC) to carry out an in-depth analysis of the flight data of GSLV-F06 as well as the data from the previous six flights of GSLV, establish reasons for the flight’s failure and recommend corrective actions on the GSLV vehicle including the remaining one Russian Cryogenic Stage.
“The Failure Analysis Committee chaired by former Chairman ISRO Dr G Madhavan Nair has 11 Experts drawn from within ISRO and outside,” Bangalore-headquartered Indian Space Research Organisation said in a statement.
The ISRO Chairman has also constituted a Programme Review and Strategy Committee to look into the future of the GSLV Programme and assured launch for INSAT/GSAT Series, INSAT-3D as well as Chandrayaan-2; realisation and operationalisation of indigenous Cryogenic Stage and strategy for meeting the demands of communication transponders in the immediate future.
Dr K Kasturirangan, former Chairman of ISRO and presently Member of the Planning Commission, would be chairing this seven member Committee.
These two Committees have been requested to submit their reports by January-end. Subsequently, the reports of these Committees would be presented to eminent national experts including Dr A P J Abdul Kalam, Prof. M G K Menon, Prof. Yash Pal, Prof. U R Rao, Dr K Kasturirangan, Dr. G Madhavan Nair, Dr R Chidambaram, and Prof. R Narasimha.
Further, a panel chaired by Dr S C Gupta, former member of Space Commission, would be guiding and facilitating an internal exercise by Chairman, ISRO, eliciting views from the ISRO community at all levels to gear up for the complex and challenging space missions ahead.
ISRO said it plans to complete these reviews and internal exercises by February end.
On the failed mission last week, ISRO said the performance of the GSLV-F06 flight of December 25 (with GSAT-5P Satellite onboard) was normal up to 47.5 seconds from lift-off.
The events leading to the failure got initiated at 47.8 seconds after lift-off. Soon, the vehicle started developing larger errors in its orientation leading to build-up of higher angle of attack and higherstructural loads and consequently vehicle broke up at 53.8 seconds from lift-off (as seen visually as well as from the Radars).
As per the Range safety norms, a destruct command was issued from the ground at 64 seconds after lift-off. The flight was hence terminated in the regime of the First Stage itself.
Soon after this, the ISRO Chairman constituted a Preliminary Failure Analysis Team under the chairmanship of Madhavan Nair, to conduct a preliminary analysis of the flight data, along with members of the Launch Authorisation Board, and Mission Readiness Review Committee as well as senior Project functionaries of GSLV Project and experts.
The finding of the Preliminary Failure Analysis Team is that the primary cause of the failure is the untimely and inadvertent snapping of a group of 10 connectors located at the bottom portion of the Russian Cryogenic Stage.
Some of these connectors carry command signals from the onboard computer residing in the Equipment Bay (located near the top of the vehicle) to the control electronics of the four L40 Strap-ons of the First Stage.
These connectors are intended to be separated only on issue of a separation command at 292 seconds after lift-off. The premature snapping of these connectors has led to stoppage of continuous flow of control commands to the First Stage control electronics, consequently leading to loss of control and break-up of the vehicle.
“The exact cause of snapping of the set of connectors, whether due to external forces like vibration, dynamic pressure is to be analysed further and pin-pointed,” ISRO said.