Was the Space Shuttle Challenger disaster avoidable?

The Space Shuttle Challenger launched its first mission April 4, 1983. The shuttle went on several voyages after the first mission. It’s last mission was on January 28, 1986 when it ended in disaster, with the explosion of the spacecraft that killed the crew. The Space Shuttle Challenger made many contributions to the evolution of space science.Was the Space Shuttle Challenger disaster avoidable? The Space Shuttle Challenger launched its first mission April 4, 1983. The shuttle went on several voyages after the first mission. It’s last mission was on January 28, 1986 when it ended in disaster, with the explosion of the spacecraft that killed the crew. The Space Shuttle Challenger made many contributions to the evolution of space science. The Space Shuttle Challenger accomplished many flights before the disaster, including STS - 6.  On the afternoon of April 4, 1983 the Challenger launched on its first mission. The missions lasted from April 4, 1983 at 1:30:00 p.m Eastern Time to April 9, 1983 at 3:42 am Pacific time. The shuttle completed 80 orbits of Earth. While orbiting the shuttle was at an inclination of 28.5 degrees.  It traveled 3,370,437 kilometers about  2,094,292 miles. The shuttles altitude ranged between 288 kilometers and 295 kilometers. The shuttle weighed 116,457 kilograms approximately 256,743.7 pounds at launch. When the shuttle landed it weighed 86,332 kilograms roughly 190,329.4 pounds. Throughout the five day span the shuttle made many strives, including the first space walk and EVA or Extra-Vehicular Activity. Performed by Loney 2Donald Penterson and Story Musgrave this space walk lasted over four hours and was a huge stride for the space shuttle program. This shuttle deployed of the first Tracking and Data Relay Satellite that photographed the challenger in flight. . “...Challenger. Launched: 1983-04-04. Returned: 1983-04-09. Number crew: 4 . Duration: 5.02 days. Payloads: Deployment of Tracking and Data Relay Satellite (TDRS)-A with Inertial Upper Stage (IUS)-2, Continuous Flow Electrophoresis System (CFES), Monodisperse Latex Reactor (MLR), Night/Day Optical Survey of Lightning (NOSL) experiment, three getaway specials (GAS).Orbits of Earth: 80. Distance traveled: 3,370,437 km ....EVA: Story Musgrave and Donald Peterson, duration 3 hours and 54 minutes.” (STS-6). The Space shuttle challenger also completed several more satellite launches in mission STS-8 and mission STS 41-B STS-8 was launched on August 30, 1983 and lasted until September 5, 1983. During this mission The Challenger deployed the INSAT-1B satellite for weather and communication data created by India. The shuttle also replaced the TDRS that was placed in orbit incorrectly. The TDSR was replaced with the Canadian built remote manipulator system also known as RMS, or robot arm, and the payload flight test article. This 8,500 pound dumbbell shaped structure was designed to evaluate the dynamics of RMS. The crew on this mission consisted of Commander Richard truly, Pilot Daniel Brandenstein and two mission specialists, Dale Gardner and Guain Bulford and Doctor William Thornton. Mr.Bulford was the first African American to ever fly in space, and is remembered ideally for this event in space history. Mission STS-41B allowed the first untethered space walk in history. The crew consisted of pilot Robert Gibson, commander Loney 3Vance Brand, and mission specialists Bruce McCandless II, Ronald Mcnair and Robert Stewart. The shuttle launched on the mission February 3, 1984 and landed February 11, 1984 after completing 128 revolution covering over 3.3 million miles. “The primary objective of Challenger’s third mission, STS-8, was to deploy the Insat-1B weather and communications satellite for India.  The final orbital location of Insat-1B dictated that Challenger launch and land at night, the first time in the Shuttle program.  STS-8 was originally planned to fly the second Tracking and Data Relay Satellite (TDRS) to expand space-to-ground communications between Mission Control and orbiting Space Shuttles, but during the launch of the first TDRS on STS-6, its Inertial Upper Stage (IUS) placed it into a stable but incorrect orbit.  NASA managers decided to replace the TDRS on STS-8 until the IUS problem could be identified and corrected.  Replacing TDRS was the Canadian-built Remote Manipulator System (RMS), or robot arm, and the Payload Flight Test Article (PFTA), an 8,500–pound dumbbell-shaped structure designed to evaluate the dynamics of the RMS.NASA announced the crew for STS-8 in April 1982– Commander Richard H. Truly, a veteran of the STS-2 mission, and three first time flyers, Pilot Daniel C. Brandenstein and Mission Specialists Dale A. Gardner and Guion S. Bluford.  Of significance, Bluford was the first African-American to fly in space.  Eight months later, NASA added Dr. William E. Thornton as a fifth member of the crew to conduct medical investigations on the astronauts to better understand the causes of space motion sickness that was then affecting approximately one-third of all space travelers.” (STS-8: The First Shuttle Night Launch & 
Loney 4Landing)  While the Space Shuttle Challenger made many contributions to Space History its career came to an unforeseen end in 1986. On January 22, 1986 the Space Shuttle Challenger was supposed to launch on mission STS-51L.  The mission was delayed due to delays in mission 61-C and was moved to January 24, 1986. The mission then was further delayed due to bad weather at the Transoceanic Abort Landing site in Dakar Senegal. “The first shuttle liftoff scheduled from Pad B, STS-51L was beset by delays. Launch was originally set for 3:43 p.m. EST, Jan. 22, 1986, slipped to Jan. 23, then Jan. 24, due to delays in mission 61-C. Launch was reset for Jan. 25 because of bad weather at the transoceanic abort landing (TAL) site in Dakar, Senegal. To utilize Casablanca (not equipped for night landings) as alternate TAL site, T-zero was moved to a morning liftoff time.” (Dunbar). Prediction of unacceptable weather at KSC a launch site led to the mission being rescheduled again to January 27, 1986.  During this time winds exceeded the return to launch site limits at KSC’s shuttle landing The mission was delayed 24 hours farther due to the ground servicing equipment hatch closing fixture not being detachable from the orbiter hatch. The fixture had to be sawed off and an attaching bolt drilled out before close out was complete. The launch was once more delayed 2 hours when a hardware interface module in the launch processing system failed during liquid hydrogen tanking procedures. “ Prediction of unacceptable weather at KSC led to the launch being rescheduled for 9:37 a.m. EST, Jan. 27. The launch was delayed 24 hours again when the ground servicing equipment hatch closing fixture could not be removed from the orbiter hatch. The fixture was sawed off and an attaching bolt Loney 5drilled out before closeout was completed. During the delay, cross winds exceeded return-to-launch site limits at KSC's Shuttle Landing Facility. The launch Jan. 28, 1986, was delayed two hours when a hardware interface module in the launch processing system, which monitors the fire detection system, failed during liquid hydrogen tanking procedures.”(Dunbar) .678 of a second into the flight photograph shows a strong puff of grey smoke spurting from around the AFT field joint on the right solid rocket booster. Initially the smoke came from the 270 degree to 310 degree set or circumference of the AFT field joint of the right solid rocket booster. The area of the solid rocket booster faced the external tank. The material streaming from the joint indicated there was not a complete seal within the joint. During the course of the explosion there were eight distinctive puffs of increasingly blacker smoke between .836 of a second and 2.5 seconds in launch. These puffs appeared upward from the joint. “Just after liftoff at .678 seconds into the flight, photographic data shows a strong puff of gray smoke was spurting from the vicinity of the aft field joint on the right solid rocket booster. Computer graphic analysis of the film from the pad cameras indicated the initial smoke came from the 270 to 310-degree sector of the circumference of the aft field joint of the right solid rocket booster. This area of the solid booster faces the external tank. The vaporized material streaming from the joint indicated there was not a complete sealing action within the joint. Eight more distinctive puffs of increasingly blacker smoke were recorded between .836 and 2.500 seconds… The last smoke was seen above the field joint at 2.733 seconds.” (Dunbar). The last smoke puff was seen above the field joint at about 2.733 seconds. The composition of the smoke and black color was the Loney 6result of grease, joint insulation, and the rubber o-rings being burned by the propellent gas. “The black color and dense composition of the smoke puffs suggest that the grease, joint insulation and rubber O-rings in the joint seal were being burned and eroded by the hot propellant gases.” (Dunbar) The main shuttle engines ran at reduced thrust approaching and the solid rockets opertrateated at reduced thrust approaching and passing through the area of maximum dynamic pressure of about 720 pounds per square foot. The main engines were throttled up to 104 percent thrust and the rocket boosters were increasing their thrust when the first flicker of flames appeared on the right solid booster in the area of the AFT field joint. The first small flame appeared on an enhanced image film at about 58.778 seconds into the flight. This flame appeared to start from about 305 degrees around the booster circumference near the AFT field joint. “Both the shuttle main engines and the solid rockets operated at reduced thrust approaching and passing through the area of maximum dynamic pressure of 720 pounds per square foot. The main engines had been throttled up to 104 percent thrust and the solid rocket boosters were increasing their thrust when the first flickering flame appeared on the right solid rocket booster in the area of the aft field joint. This first very small flame was detected on image enhanced film at 58.788 seconds into the flight. It appeared to originate at about 305 degrees around the booster circumference at or near the aft field joint.” (Dunbar) The flame became well defined at approximately 59.262 seconds after launch. At the same point telemetry, the process of recording and transmitting the readings of an instrument, showed pressure differences between the chamber pressures in the left and right boosters. The low pressure in the right booster chamber confirmed the growing leak in Loney 7the area of the field joint. “t grew into a continuous, well-defined plume at 59.262 seconds. At about the same time (60 seconds), telemetry showed a pressure differential between the chamber pressures in the right and left boosters. The right booster chamber pressure was lower, confirming the growing leak in the area of the field joint.” (Dunbar). As the flames grew, they were deflected toward the back by “aerodynamic slipstream and circumferentially by the protruding structure of the upper ring attaching the booster onto the surface of the external tank. These resulted in the flame plume being directed onto the surface of external tank”.(Dunbar) The heightening flames damaged the strut attaching the solid rocket to the external tank.  The first visual signal the flames breached the external tank was 64.66 seconds after liftoff when there was an abrupt change in the shape and color of the plum. This was an indication that “it was mixing with leaking hydrogen from the external tank”.(Dunbar) Documented changes in the pressurization of the tank later confirmed the leak. Within 45 milliseconds of the breach a bright sustained glow developed on the back tiled underside of the challenger between it and the external tank. “Telemetered changes in the hydrogen tank pressurization confirmed the leak. Within 45 milliseconds of the breach of the external tank, a bright sustained glow developed on the black-tiled underside of the Challenger between it and the external tank.” (Dunbar) At approximately 72 seconds a series of extremely rapid changes terminated the flight. Data indicate a wide variety of flight system actions support visual evidence that this accident was trying to be corrected by the shuttle. At 73.124 seconds a a white vapor in a circumferential pattern was observed blooming from the side of the external tank bottom dome. This was the introduction of Loney 8the structural failure of the hydrogen tank the accumulated in the entire AFT dome dropping away. This allowed the release of liquid hydrogen from the tank. This created a sudden forward thrust of about 2.8 million pounds, pushing the tank upward into an intertank structure. Concurrently the rotating right solid rocket booster impacted the intertank structure and the lower part of the liquid oxygen tank. All of the structures failed at 73.137 seconds as white vapors appeared on the inside of the intertank region. Within milliseconds there was a massive almost explosive burn of the shuttle. At this point the shuttle was traveling at a march number of 1.92 and an altitude of 46,000 feet. The shuttle was completely enveloped by this point and it’s reaction control system ruptured and a hypergolic burn of it’s propellants occurred as it exited the aerodynamic loads, broke into several large sections which emerged from the fireball. Several pieces can be identified in the films including the main engine/Tal section with the engine still burning one wing of the orbiter and the forward fuselage trailing a mass of umbilical lines pulled loose from the payload bay. This explosion claimed the crew and vehicle. ”At 73.124 seconds, a circumferential white vapor pattern was observed blooming from the side of the external tank bottom dome. This was the beginning of the structural failure of hydrogen tank that culminated in the entire aft dome dropping away. This released massive amounts of liquid hydrogen from the tank and created a sudden forward thrust of about 2.8 million pounds, pushing the hydrogen tank upward into the intertank structure. At about the same time, the rotating right solid rocket booster impacted the intertank structure and the lower part of the liquid oxygen tank. These structures failed at 73.137 seconds as evidenced by the white vapors appearing in the intertank region. Loney 9Within milliseconds there was massive, almost explosive, burning of the hydrogen streaming from the failed tank bottom and liquid oxygen breach in the area of the intertank.” (Dunbar). The cause was found to be an o-ring failure in the right solid rocket booster caused by the cold weather. “The explosion 73 seconds after liftoff claimed crew and vehicle. The cause of explosion was determined to be an o-ring failure in the right solid rocket booster. Cold weather was determined to be a contributing factor.” (Dunbar) The space shuttle challenger was an important part of space history and science.These are just some of the space shuttles many contributions to the space shuttle program and to the evolution of the space science. The space shuttle challenger launched on it’s first mission STS-6 on the afternoon of April 4, 1983. On this mission it launched several satellites. The shuttle later launched on mission STS-8 on August 30, 1983. This mission launched the INSAT-1B satellite for weather and communication and replaced the TDSR satellite. The shuttle also completed shuttle mission 41-B that launched on the February 3, 1984 and allowed the first untethered spacewalk to take place. The  shuttles missions ended in tragedy on January 22, 1986 when the space shuttle exploded just 73 seconds into mission STS 61-C. While the Shuttles history ended in disaster it should be remembered for its contributions to space history.