Challenger Accident - Part III Photo and Video Analysis

at 72 seconds the guidance system showed that right SRB motion from the orbiter and left SRB indicating that the lower ETS RB strut was severed or pulled loose during this timeframe exaggerated steering commands and control system responses registered in telemetry data at approximately 73 seconds spoke liquid hydrogen and liquid oxygen pressure to the main engines showed a significant drop this was followed at seventy three point one to four seconds by the appearance of a circumferential white pattern around the ET aft region suggesting LH to tank structural failure 13 milliseconds later at seventy three point one thirty seven seconds vapor was observed at the inner tank indicative of the liquid oxygen tank failing this can be attributed to have normal loads induced by either the right SRB rotation at the forward attached point or the propulsive forces created by the LH to tank aft bulkhead failure probably both within milliseconds liquid oxygen was observed streaming along the external tank at seventy three point one nine one seconds a flash was observed between the ET and orbiter that was immediately followed by the start of total vehicle breakup at seventy three point two one three seconds during the next 100 milliseconds additional flashes occur in the SRB forward attach area as the ET broke up the released fluids vaporized rapidly producing an expanding cloud of gases vapors and cryogenic fluid with embedded debris and localized combustion of mixed gases no shockwave or other evidence of a violent explosion was detected in the imagery illumination from a combination of SRB plume radiance reflected sunlight and peripheral burning of gases gives the cloud the appearance of a fireball by seventy three point six seconds the main engines were in automatic shutdown mode as a result of reduced propellant pressures the last telemetry from challenger was received seventy three point six one eight seconds after launch the actual vehicle breakup was essentially obscured from view by the vapor cloud which abruptly enveloped the vehicle hundreds of fragments were noted exiting the et cloud those identified included the shuttle main engines the left wing crew cabin and both SRBs approximately one second after initial breakup film showed the front segment of the orbiter emerging from the cloud the nose crew cabin and a portion of the cargo bay makeup the orbiter in this view nitrogen tetroxide oxidizer from the forward reaction control system provided a distinctive orange brown color to the cloud by seventy four point five seven eight seconds a yellow cloud or flash was visible near the orbiter nose segment this is believed to be caused by burning monomethylhydrazine from the forward RCS the flash reaction from the RCS propellant sub aided revealing separation of the nose section from the crew cabin less than a quarter of a second later the crew cabin was noted to be severed from the cargo bay igniting a propellant discharge continued to be observed from the forward RCS a camera south of the launch pad recorded a wider array of debris exiting the vapor cloud the initial emergence of the crew cabin from this perspective was at seventy five point two three seven seconds the initial path of the crew cabin from the vapor cloud carried it across the path of an adjacent contrail clearly revealing its truncated form and attitude the left wing became visible at seventy eight point five three one seconds the main engines and crew cabin are also identifiable after ten seconds the crew cabin was seen again with the front end and top of the cabin visible as the subject moved further away and dropped lower on the horizon the quality of the image for visual analysis deteriorated rapidly long-range tracking cameras followed the SRBs through Range Safety destruct at approximately seventy five point eight seconds the right SRB was seen exiting the cloud camera E to O seven shows the right SRB after the breakup and the joints are clearly visible except for the aft field joint this confirmed the location of the plume along the longitudinal axis of the SRB the separated nose cap and deployed drogue parachute are identified at approximately seventy six point four seconds the shockwave from the detonation of the linear shaped charge on the right SRB can be seen clearly simultaneously the left SRB was destroyed approximately 37 seconds challenger had encountered the first of several expected high altitude wind shear conditions which lasted until about 64 seconds these wind shears are best illustrated by the effect on the booster exhaust trails the effect of wind shear was immediately sensed and countered by the guidance navigation and control system wind reconstructions were aided by comparing predicted exhaust trail shapes with acquired photography the reconstructed winds were used in trajectory and flight loads analyses which verified that the loads were within limits several flashes in the ssme plumes were observed during the flight as similar flashes have been seen on several previous flights they are considered not to have contributed to the accident the visible condensation that appears in this frame is created by shockwaves which develop as the vehicle passes through the speed of sound a large-scale search effort was initiated to recover the space shuttle debris 22 ships six underwater search vessels and 33 aircraft participated in the operation the pieces recovered initially were those found floating on the surface the submarine fleet was used to locate and inspect underwater debris objects identified as being important to the investigation were retrieved 50% of the entire vehicle was recovered in the effort the ocean search area was located at the edge of the Gulf Stream at depths up to 1,200 feet approximately 93 thousand square miles of ocean were searched the recovered hardware was brought to the logistics facility where reconstruction efforts helped to verify the investigation team's findings as well as to analyze the structural break-up mechanics of the orbiter ET and SRBs inside the logistics facility parts were arranged on the floor according to their location on the vehicle 45 percent of the orbiter itself was recovered the debris confirmed that the orbiter and its payloads did not contribute to the cause of the accident and that the orbiter breakup was a result of aerodynamic effects rather than explosive effects shown here are parts of the orbiter forward fuselage structure which surrounds the crew cabin extensive heating and erosion was detected on the right aft section of the orbiter the paint was scorched and blackened on the right side of the aft fuselage thermal distress was apparent on the right rudder speed brake while the left showed little effect thermal effects were also seen on the Elavon the aft left side of the orbiter showed no apparent sign of heat damage the remaining recovered parts of the orbiter showed no evidence of fire or explosion from within the vehicle all three main engines were recovered and helped to verify that they did not contribute to the cause of the accident the external tank was similarly reconstructed 25% of the liquid hydrogen tank 80 percent of the inner tank and 5% of the liquid oxygen tank was recovered most of the external hardware was also recovered the nose cap sustained very little damage in general the recovered pieces were quite large the spray-on foam insulation exhibited varying degrees of thermal effects from extreme charring to practically no effect the external tank range safety destruct exclusive charges housed in this cable tray were recovered undetonated eliminating them as a possible factor in external tank breakup the inner tank region showed signs of buckling in the fore and aft direction this would be consistent with the impulsive thrust that resulted from the sudden loss of liquid hydrogen from the aft section of the tank this sharing failure of the forward attachment fitting with the right SRB was caused by the boosters rotation after the aft strut area failed the stiffener stringers on the right hand side of the inner tank show evidence of contact which match marks on the forward assembly of the right SRB a section of the ring frame and a section of the a film from the lower strut attachment area was recovered in one piece the lower strut attachment fitting had been pulled away the effects of the anomalous SRB plume can be seen on the external tank excluding an area which was shielded by the strut and attachment fitting approximately 50% of solid rocket booster Hardware was recovered an ordnance storage facility was used to house the motor case pieces as some contained unburned propellant marks seen on the right SRB frustum matched the contact areas shown previously on the et inter tank stringers the size and location of the burn through as indicated by the recovered SRB debris were illustrated on an assembled booster the aft center section of the joint shows a large hole centered at the 307 degrees circumferential position the irregular hole is roughly rectangular and is about 27 by 15 inches the Steelcase material showed evidence of hot gas erosion caused by combustion products flowing through the opening the aft section of the right SRB showed a hole approximately 33 by 21 inches the burned surface extended into the aft attached strut region the exterior surface of the aft case featured a large heat affected area the shape and location of this heat spot indicates an impingement from the escaping gases there was a small burn through in the case wall which appeared to have penetrated from the outside in this was due to the impingement of hot gases from the anomalous plume the hole in the solid rocket booster segments was the result of the joint leakage on the right hand SRB which was determined to be the cause of the accident the presidential commission concluded that the cause of the Challenger accident was the failure of the pressure seal in the aft field joint of the right solid rocket motor the failure was due to a faulty design rendering the seal unacceptably sensitive to a number of factors those factors include the effects of temperature physical dimensions the character of materials the effects of reuse and processing and the reaction of the joint to dynamic loading more detailed analyses are contained in volume 3 of the report of the Presidential Commission on the space shuttle Challenger accident you

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Keywords: Challenger, Space Shuttle Program, Endeavour, Atlantis, Space Shuttle, McAullife, Rogers Commission, Christa McAuliife, Orbiter, moon, Space Shuttle Columbia, Space Shuttle Accident, vision for space exploration, Space Shuttle Challenger, Discovery, Shuttle, Scobee, Teacher in Space, Space Shuttle Disaster, space, space program, Reagan, Resnick, NASA, VAB, science

Id: tfTh8FwrEmY

Length: 14min 59sec (899 seconds)

Published: Sun Mar 27 2011