The Advanced Launch System (ALS) is a joint United States Air Force (USAF) and National Aeronautics and Space Administration (NASA) study which operated from 1987 to 1990. Its aim was to develop a flexible, modular, heavy-lift, high rate space launch vehicle that could deliver payloads to Earth orbit at a tenth the cost of existing boosters .
143-650: The ALS was a joint USAF and NASA study from 1987 to 1990. It was an endeavour of the years following the Space Shuttle Challenger disaster . Colonel John R. Wormington (retired Brigadier General USAF) was the Program Director of the Joint Department of Defense and NASA Advanced Launch System Program Office. Lieutenant Colonel Michael C. Mushala (retired Major General USAF) was assigned as Wormington's deputy. The program operated from
286-484: A C-141 Starlifter aircraft from Kennedy Space Center to the military mortuary at Dover Air Force Base in Delaware . Their caskets were each draped with an American flag and carried past an honor guard and followed by an astronaut escort. After the remains arrived at Dover Air Force Base, they were transferred to the families of the crew members. Scobee and Smith were buried at Arlington National Cemetery . Onizuka
429-582: A 20-foot (6 m) piece of the shuttle had been found near the site of a destroyed World War II-era aircraft off the coast of Florida. The discovery was aired on the History Channel on November 22, 2022. Almost all recovered non-organic debris from Challenger is buried in Cape Canaveral Space Force Station missile silos at LC-31 and LC-32 . On April 29, 1986, the astronauts' remains were transferred on
572-521: A crewed orbiter. To replace Challenger , the construction of a new Space Shuttle orbiter, Endeavour , was approved in 1987, and the new orbiter first flew in 1992. Subsequent missions were launched with redesigned SRBs and their crews wore pressurized suits during ascent and reentry . The Space Shuttle was a partially reusable spacecraft operated by the US National Aeronautics and Space Administration (NASA). It flew for
715-555: A double bore seal, and the gap between segments was filled with putty. When the motor was running, this configuration was designed to compress air in the gap against the upper O-ring, pressing it against the sealing surfaces of its seat. On the SRB Critical Items List, the O-rings were listed as Criticality 1R, which indicated that an O-ring failure could result in the destruction of the vehicle and loss of life, but it
858-628: A final cost just under $ 3 billion. The ALS program office differed from others in that it was the only one within the Air Force Space Command . The office was furnished with Apple Mac OS personal computers instead of the Command's usual Microsoft Windows systems. This was in part because NASA had already been using Apple computers. The program office pioneered what later became the Microsoft Project . The ALS program
1001-437: A force equating to roughly 3,000,000 pounds-force (13 meganewtons), while the right SRB collided with the intertank structure. These events resulted in an abrupt change to the shuttle stack's attitude and direction, which was shrouded from view by the vaporized contents of the now-destroyed ET. As it traveled at Mach 1.92, Challenger took aerodynamic forces it was not designed to withstand and broke into several large pieces:
1144-514: A gearbox. The waste gas, now cooler and at low pressure, was passed back over the gas generator housing to cool it before being dumped overboard. The gearbox drove the fuel pump, its own lubrication pump, and the HPU hydraulic pump. A startup bypass line went around the pump and fed the gas generator using the nitrogen tank pressure until the APU speed was such that the fuel pump outlet pressure exceeded that of
1287-441: A glass of cold water and a piece of rubber, for which he received media attention. Feynman, a Nobel Prize -winning physicist, advocated for harsher criticism towards NASA in the report and repeatedly disagreed with Rogers. He threatened to remove his name from the report unless it included his personal observations on reliability, which appeared as Appendix F. In the appendix, he lauded the engineering and software accomplishments in
1430-502: A hydraulic pump that produced hydraulic pressure for the SRB hydraulic system. The two separate HPUs and two hydraulic systems were located on the aft end of each SRB between the SRB nozzle and aft skirt. The HPU components were mounted on the aft skirt between the rock and tilt actuators. The two systems operated from T minus 28 seconds until SRB separation from the orbiter and external tank. The two independent hydraulic systems were connected to
1573-571: A launch hold. Electrical power distribution in each SRB consisted of orbiter-supplied main DC bus power to each SRB via SRB buses labeled A, B and C. Orbiter main DC buses A, B and C supplied main DC bus power to corresponding SRB buses A, B and C. In addition, orbiter main DC bus C supplied backup power to SRB buses A and B, and orbiter bus B supplied backup power to SRB bus C. This electrical power distribution arrangement allowed all SRB buses to remain powered in
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#17327764901211716-483: A manual lock pin from each SRB safe and arm device has been removed. The ground crew removes the pin during prelaunch activities. At T−5:00, the SRB safe and arm device is rotated to the arm position. The solid rocket motor ignition commands are issued when the three Space Shuttle Main Engines (SSMEs) are at or above 90% of rated thrust, no SSME fail and/or SRB ignition Pyrotechnic Initiator Controller (PIC) low voltage
1859-475: A post-flight inspection of the left SRB on STS-41-D revealed that soot had blown past the primary O-ring and was found in between the O-rings. Although there was no damage to the secondary O-ring, this indicated that the primary O-ring was not creating a reliable seal and was allowing hot gas to pass. The amount of O-ring erosion was insufficient to prevent the O-ring from sealing, and investigators concluded that
2002-623: A potentially catastrophic flaw in the SRBs' O-rings, but neither NASA nor SRB manufacturer Morton Thiokol had addressed this known defect. NASA managers also disregarded engineers' warnings about the dangers of launching in cold temperatures and did not report these technical concerns to their superiors. As a result of this disaster, NASA established the Office of Safety, Reliability, and Quality Assurance, and arranged for deployment of commercial satellites from expendable launch vehicles rather than from
2145-440: A predetermined time, an isolating valve would be selected, excluding it from the force-sum entirely. Failure monitors were provided for each channel to indicate which channel had been bypassed, and the isolation valve on each channel could be reset. Each actuator ram was equipped with transducers for position feedback to the thrust vector control system. Within each servoactuator ram was a splashdown load relief assembly to cushion
2288-407: A redesigned field joint that introduced a metal lip to limit movement in the joint. They also recommended adding a spacer to provide additional thermal protection and using an O-ring with a larger cross section. In July 1985, Morton Thiokol ordered redesigned SRB casings, with the intention of using already-manufactured casings for the upcoming launches until the redesigned cases were available
2431-426: A report on the deaths of the crew from physician and Skylab 2 astronaut Joseph P. Kerwin : The findings are inconclusive. The impact of the crew compartment with the ocean surface was so violent that evidence of damage occurring in the seconds which followed the disintegration was masked. Our final conclusions are: Pressurization could have enabled consciousness for the entire fall until impact. The crew cabin hit
2574-499: A risk management review for all critical systems. Space Shuttle Solid Rocket Booster The Space Shuttle Solid Rocket Booster ( SRB ) was the first solid-propellant rocket to be used for primary propulsion on a vehicle used for human spaceflight . A pair of them provided 85% of the Space Shuttle 's thrust at liftoff and for the first two minutes of ascent. After burnout, they were jettisoned, and parachuted into
2717-603: A rocket or part of it with on-board explosives by remote command if the rocket is out of control, in order to limit the danger to people on the ground from crashing pieces, explosions, fire, poisonous substances, etc. The RSS was only activated once – during the Space Shuttle Challenger disaster (37 seconds after the breakup of the vehicle, when the SRBs were in uncontrolled flight). The shuttle vehicle had two RSS, one in each SRB. Both were capable of receiving two command messages (arm and fire) transmitted from
2860-478: A specific energy density of about 31.0 MJ/kg . The propellant had an 11-pointed star-shaped perforation in the forward motor segment and a double-truncated- cone perforation in each of the aft segments and aft closure. This configuration provided high thrust at ignition and then reduced the thrust by approximately a third 50 seconds after lift-off to avoid overstressing the vehicle during maximum dynamic pressure (max. Q). SRB ignition can occur only when
3003-507: A speed of 3,094 mph (4,979 km/h) along with the main engines. The SRBs committed the shuttle to liftoff and ascent, without the possibility of launch abort, until both motors had fully consumed their propellants and had simultaneously been jettisoned by explosive jettisoning bolts from the remainder of the vehicle. Only then could any conceivable set of launch or post-liftoff abort procedures be contemplated. In addition, failure of an individual SRB's thrust output or ability to adhere to
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#17327764901213146-478: A switching valve that allowed the hydraulic power to be distributed from either HPU to both actuators if necessary. Each HPU served as the primary hydraulic source for one servoactuator, and a secondary source for the other servoactuator. Each HPU possessed the capacity to provide hydraulic power to both servoactuators within 115% operational limits in the event that hydraulic pressure from the other HPU should drop below 2,050 psi (14.1 MPa). A switch contact on
3289-754: A switchover was made from the SRB RGAs to the orbiter RGAs. The SRB RGA rates passed through the orbiter flight aft multiplexers/demultiplexers to the orbiter GPCs. The RGA rates were then mid-value-selected in redundancy management to provide SRB pitch and yaw rates to the user software. The RGAs were designed for 20 missions. Made out of 2-cm-thick D6AC high-strength low-alloy steel . The rocket propellant mixture in each solid rocket motor consisted of ammonium perchlorate ( oxidizer , 69.6% by weight), atomized aluminum powder ( fuel , 16%), iron oxide ( catalyst , 0.4%), PBAN (binder, also acts as fuel, 12.04%), and an epoxy curing agent (1.96%). This propellant
3432-476: A tang from the upper segment fitting into the clevis of the lower segment. Each field joint was sealed with two ~20 foot (6 meter) diameter Viton-rubber O-rings around the circumference of the SRB and had a cross-section diameter of 0.280 inches (7.1 mm). The O-rings were required to contain the hot, high-pressure gases produced by the burning solid propellant and allowed for the SRBs to be rated for crewed missions. The two O-rings were configured to create
3575-493: A wing, the (still firing) main engines, the crew cabin and hypergolic fuel leaking from the ruptured reaction control system were among the parts identified exiting the vapor cloud. The disaster unfolded at an altitude of 46,000 feet (14 km). Both SRBs survived the breakup of the shuttle stack and continued flying, now unguided by the attitude and trajectory control of their mothership, until their flight termination systems were activated at T+110 . At T+73.191 , there
3718-474: Is commonly referred to as ammonium perchlorate composite propellant (APCP). This mixture gave the solid rocket motors a specific impulse of 242 seconds (2.37 km/s) at sea level or 268 seconds (2.63 km/s) in a vacuum. Upon ignition, the motor burned the fuel at a nominal chamber pressure of 906.8 psi (6.252 MPa). Aluminum was chosen as a propellant due to high volumetric energy density, and its resilience to accidental ignition. Aluminum has
3861-518: Is estimated to have been between 12 and 20 times that of gravity ( g ). Within two seconds it had dropped below 4 g, and within ten seconds the cabin was in free fall . The forces involved at this stage were probably insufficient to cause major injury to the crew. At least some of the crew were alive and conscious after the breakup, as Personal Egress Air Packs (PEAPs) were activated for Smith and two unidentified crewmembers, but not for Scobee. The PEAPs were not intended for in-flight use, and
4004-400: Is held for four seconds, and SRB thrust drops to less than 60,000 lbf (270 kN). The SRBs separate from the external tank within 30 milliseconds of the ordnance firing command. The forward attachment point consists of a ball (SRB) and socket (External Tank; ET) held together by one bolt. The bolt contains one NSD pressure cartridge at each end. The forward attachment point also carries
4147-574: Is indicated and there are no holds from the Launch Processing System (LPS). The solid rocket motor ignition commands are sent by the orbiter computers through the Master Events Controllers (MECs) to the safe and arm device NASA standard detonators (NSDs) in each SRB. A PIC single-channel capacitor discharge device controls the firing of each pyrotechnic device. Three signals must be present simultaneously for
4290-434: Is less than or equal to 50 psi (340 kPa). A backup cue is the time elapsed from booster ignition. The separation sequence is initiated, commanding the thrust vector control actuators to the null position and putting the main propulsion system into a second-stage configuration (0.8 seconds from sequence initialization), which ensures the thrust of each SRB is less than 100,000 lbf (440 kN). Orbiter yaw attitude
4433-701: The Atlantic Ocean under a parachute. NASA retrieval teams recovered the SRBs and returned them to the Kennedy Space Center (KSC), where they were disassembled and their components were reused on future flights. Each SRB was constructed in four main sections at the factory in Utah and transported to KSC, then assembled in the Vehicle Assembly Building at KSC with three tang-and-clevis field joints, each joint consisting of
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4576-538: The Johnson Space Center (JSC) who advised him that ice did not threaten the safety of the orbiter, and he decided to proceed with the launch. The launch was delayed for an additional hour to allow more ice to melt. The ice team performed an inspection at T–20 minutes which indicated that the ice was melting, and Challenger was cleared to launch at 11:38 a.m. EST, with an air temperature of 36 °F (2 °C). At T+0, Challenger launched from
4719-568: The Kennedy Space Center Launch Complex 39B (LC-39B) at 11:38:00 a.m. Beginning at T+0.678 until T+3.375 seconds, nine puffs of dark gray smoke were recorded escaping from the right-hand SRB near the aft strut that attached the booster to the ET . It was later determined that these smoke puffs were caused by joint rotation in the aft field joint of the right-hand SRB at ignition. The cold temperature in
4862-497: The Launch Commit Criteria . In addition to its effect on the O-rings, the cold temperatures caused ice to form on the fixed service structure . To keep pipes from freezing, water was slowly run from the system; it could not be entirely drained because of the upcoming launch. As a result, ice formed from 240 feet (73 m) down in the freezing temperatures. Engineers at Rockwell International , which manufactured
5005-601: The Los Angeles Air Force Base . In October 1989, Mushala was promoted to Colonel. In February 1990, Wormington was reassigned to command the 45th Space Wing at Patrick Air Force Base in Florida . Mushala became the program director and remained so until the project was disbanded in July 1990. Although the project had a projected research and development cost of $ 15 billion, its early cancellation led to
5148-472: The Space Shuttle Challenger broke apart 73 seconds into its flight, killing all seven crew members aboard. The spacecraft disintegrated 46,000 feet (14 km) above the Atlantic Ocean, off the coast of Cape Canaveral , Florida, at 11:39 a.m. EST (16:39 UTC ). It was the first fatal accident involving an American spacecraft while in flight. The mission, designated STS-51-L ,
5291-422: The Space Shuttle program . Challenger (OV-099) was the second orbiter constructed after its conversion from a structural test article . The orbiter contained the crew compartment, where the crew predominantly lived and worked throughout a mission. Three Space Shuttle main engines (SSMEs) were mounted at the aft end of the orbiter and provided thrust during launch. Once in space, the crew maneuvered using
5434-503: The death certificates ; NASA officials ultimately released the death certificates of the crew members. The IUS that would have been used to boost the orbit of the TDRS-B satellite was one of the first pieces of debris recovered. There was no indication that there had been premature ignition of the IUS, which had been one of the suspected causes for the disaster. Debris from the three SSMEs
5577-412: The range safety officer destroyed them. The crew compartment, human remains, and many other fragments from the shuttle were recovered from the ocean floor after a three-month search-and-recovery operation. The exact timing of the deaths of the crew is unknown, but several crew members are thought to have survived the initial breakup of the spacecraft. The orbiter had no escape system , and the impact of
5720-528: The 196,726 lb (89,233 kg) of both SRB shells, 102,500 lb (46,500 kg) was recovered, another 54,000 lb (24,000 kg) was found but not recovered, and 40,226 lb (18,246 kg) was never found. On March 7, Air Force divers identified potential crew compartment debris, which was confirmed the next day by divers from the USS Preserver . The damage to the crew compartment indicated that it had remained largely intact during
5863-520: The Atlantic Ocean, where they were recovered , examined, refurbished, and reused . The Space Shuttle SRBs were the most powerful solid rocket motors to ever launch humans. The Space Launch System (SLS) SRBs, adapted from the shuttle, surpassed it as the most powerful solid rocket motors ever flown, after the launch of the Artemis 1 mission in 2022. Each Space Shuttle SRB provided a maximum 14.7 MN (3,300,000 lbf ) thrust, roughly double
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6006-531: The ET, causing lateral acceleration that was felt by the crew. At the same time, pressure in the LH2 tank began dropping. Pilot Mike Smith said "Uh-oh," which was the last crew comment recorded. At T+73.124 , white vapor was seen flowing away from the ET, after which the aft dome of the LH2 tank fell off. The resulting release of all liquid hydrogen in the tank pushed the LH2 tank forward into the liquid oxygen (LOX) tank with
6149-583: The NASA Verification/Certification Committee requested further tests on joint integrity to include testing in the temperature range of 40 to 90 °F (4 to 32 °C) and with only a single O-ring installed. The NASA program managers decided that their current level of testing was sufficient and further testing was not required. In December 1982, the Critical Items List was updated to indicate that
6292-590: The NASA accident investigation, the Space Shuttle program, and the Morton Thiokol recommendation to launch despite O-ring safety issues. On February 15, Rogers released a statement that established the commission's changing role to investigate the accident independent of NASA due to concerns of the failures of the internal processes at NASA. The commission created four investigative panels to research
6435-443: The NASA administrator to oversee all safety, reliability, and quality assurance functions in NASA programs. Additionally, the commission addressed issues with overall safety and maintenance for the orbiter, and it recommended the addition of the means for the crew to escape during controlled gliding flight. During a televised hearing on February 11, Feynman demonstrated the loss of rubber's elasticity in cold temperatures using
6578-684: The O-rings would seal at temperatures colder than 53 °F (12 °C), the coldest launch of the Space Shuttle to date. Morton Thiokol employees Robert Lund, the Vice President of Engineering, and Joe Kilminster, the Vice President of the Space Booster Programs, recommended against launching until the temperature was above 53 °F (12 °C). The teleconference held a recess to allow for private discussion amongst Morton Thiokol management. When it resumed, Morton Thiokol leadership had changed their opinion and stated that
6721-567: The PIC to generate the pyro firing output. These signals, arm, fire 1 and fire 2, originate in the orbiter general-purpose computers (GPCs) and are transmitted to the MECs. The MECs reformat them to 28 volt DC signals for the PICs. The arm signal charges the PIC capacitor to 40 volts DC (minimum of 20 volts DC). The GPC launch sequence also controls certain critical main propulsion system valves and monitors
6864-424: The SRB. The solid rocket motor ignition commands were issued by the orbiter's computers through the master events controllers to the hold-down pyrotechnic initiator controllers (PICs) on the mobile launcher platform . They provided the ignition to the hold-down NSDs. The launch processing system monitored the SRB hold-down PICs for low voltage during the last 16 seconds before launch. PIC low voltage would initiate
7007-486: The SRBs from the external tank. The solid rocket motors in each cluster of four are ignited by firing redundant NSD pressure cartridges into redundant confined detonating fuse manifolds. The separation commands issued from the orbiter by the SRB separation sequence initiate the redundant NSD pressure cartridge in each bolt and ignite the BSMs to effect a clean separation. A range safety system (RSS) provides for destruction of
7150-540: The SRBs were kept wet during recovery, and their unused propellant was ignited once they were brought ashore. The failed joint on the right SRB was first located on sonar on March 1. Subsequent dives to 560 ft (170 m) by the NR-1 submarine on April 5 and the SEA-LINK I submersible on April 12 confirmed that it was the damaged field joint, and it was successfully recovered on April 13. Of
7293-487: The SRBs, as well as for the integration of all the components and retrieval of the spent SRBs, was USBI, a subsidiary of Pratt & Whitney . The contract was subsequently transitioned to United Space Alliance , a joint venture of Boeing and Lockheed Martin . Out of 270 SRBs launched over the Shuttle program, all but four were recovered – those from STS-4 (due to a parachute malfunction) and STS-51-L ( terminated by
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#17327764901217436-658: The State of the Union, and instead addressed the nation about the disaster from the Oval Office . On January 31, Ronald and Nancy Reagan traveled to the Johnson Space Center to speak at a memorial service honoring the crew members. During the ceremony, an Air Force band sang " God Bless America " as NASA T-38 Talon jets flew directly over the scene in the traditional missing-man formation . Soon after
7579-591: The Sun, and deploy and retrieve a SPARTAN satellite. The mission was originally scheduled for July 1985, but was delayed to November and then to January 1986. The mission was scheduled to launch on January 22, but was delayed until January 28. The air temperature on January 28 was predicted to be a record low for a Space Shuttle launch. The air temperature was forecast to drop to 18 °F (−8 °C) overnight before rising to 22 °F (−6 °C) at 6:00 a.m. and 26 °F (−3 °C) at
7722-550: The Union speech. In that speech, Reagan had intended to mention an X-ray experiment launched on Challenger and designed by a guest he had invited to the address, but he did not further discuss the Challenger launch. In the rescheduled State of the Union address on February 4, Reagan mentioned the deceased Challenger crew members and modified his remarks about the X-ray experiment as "launched and lost". In April 1986,
7865-474: The United States. The cause of the disaster was the failure of the primary and secondary O-ring seals in a joint in the shuttle's right solid rocket booster (SRB). The record-low temperatures on the morning of the launch had stiffened the rubber O-rings, reducing their ability to seal the joints. Shortly after liftoff, the seals were breached, and hot pressurized gas from within the SRB leaked through
8008-745: The White House released a report that concluded there had been no pressure from the White House for NASA to launch Challenger prior to the State of the Union. Nationally televised live coverage of the launch and explosion was provided by CNN . To promote the Teacher in Space program with McAuliffe as a crewmember, NASA had arranged for many students in the US to view the launch live at school with their teachers. Other networks, such as CBS , soon cut in to their affiliate feeds to broadcast continuous coverage of
8151-405: The aft attach strut on the right SRB, right before the vehicle passed through max q at T+59.000 . The high aerodynamic forces and wind shear likely broke the aluminum oxide seal that had replaced eroded O-rings, allowing the flame to burn through the joint. Within one second from when it was first recorded, the plume became well-defined, and the enlarging hole caused a drop in internal pressure in
8294-607: The amount of training, quality control, and repair work that was available for each mission. The commission published a series of recommendations to improve the safety of the Space Shuttle program. It proposed a redesign of the joints in the SRB that would prevent gas from blowing past the O-rings. It also recommended that the program's management be restructured to keep project managers from being pressured to adhere to unsafe organizational deadlines, and should include astronauts to address crew safety concerns better. It proposed that an office for safety be established reporting directly to
8437-591: The astronauts never trained with them for an in-flight emergency. The location of Smith's activation switch, on the back side of his seat, indicated that either Resnik or Onizuka likely activated it for him. Investigators found their remaining unused air supply consistent with the expected consumption during the post-breakup trajectory. While analyzing the wreckage, investigators discovered that several electrical system switches on Smith's right-hand panel had been moved from their usual launch positions. The switches had lever locks on top of them that must be pulled out before
8580-486: The atmosphere, where it would break apart during reentry and its pieces would land in the Indian or Pacific Ocean . Two solid rocket boosters (SRBs), built by Morton Thiokol at the time of the disaster, provided the majority of thrust at liftoff. They were connected to the external tank, and burned for the first two minutes of flight. The SRBs separated from the orbiter once they had expended their fuel and fell into
8723-423: The bypass line, at which point all the fuel was supplied to the fuel pump. When the APU speed reached 100%, the APU primary control valve closed, and the APU speed was controlled by the APU controller electronics. If the primary control valve logic failed to the open state, the secondary control valve assumed control of the APU at 112% speed. Each HPU on an SRB was connected to both servoactuators on that SRB by
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#17327764901218866-464: The cause of the accident was hot gas blowing past the O-rings in the field joint on the right SRB, and found no other potential causes for the disaster. It attributed the accident to a faulty design of the field joint that was unacceptably sensitive to changes in temperature, dynamic loading, and the character of its materials. The report was critical of NASA and Morton Thiokol, and emphasized that both organizations had overlooked evidence that indicated
9009-491: The cold temperatures caused a loss of flexibility in the O-rings that decreased their ability to seal the field joints, which allowed hot gas and soot to flow past the primary O-ring. O-ring erosion occurred on all but one ( STS-51-J ) of the Space Shuttle flights in 1985, and erosion of both the primary and secondary O-rings occurred on STS-51-B . To correct the issues with O-ring erosion, engineers at Morton Thiokol, led by Allan McDonald and Roger Boisjoly , proposed
9152-489: The commands to each servoactuator of the main engines and SRBs. Four independent flight control system channels and four ATVC channels controlled six main engine and four SRB ATVC drivers, with each driver controlling one hydraulic port on each main and SRB servoactuator. Each SRB servoactuator consisted of four independent, two-stage servovalves that received signals from the drivers. Each servovalve controlled one power spool in each actuator, which positioned an actuator ram and
9295-491: The crew compartment at terminal velocity with the ocean surface was too violent to be survivable. The disaster resulted in a 32-month hiatus in the Space Shuttle program . President Ronald Reagan created the Rogers Commission to investigate the accident. The commission criticized NASA 's organizational culture and decision-making processes that had contributed to the accident. Test data since 1977 demonstrated
9438-475: The dangers of groupthink . Roger Boisjoly and Allan McDonald became speakers who advocated for responsible workplace decision making and engineering ethics. Information designer Edward Tufte has argued that the Challenger accident was the result of poor communications and overly complicated explanations on the part of engineers, and stated that showing the correlation of ambient air temperature and O-ring erosion amounts would have been sufficient to communicate
9581-520: The designed performance profile was probably not survivable. The SRBs were the largest solid-propellant motors ever flown and the first of such large rockets designed for reuse. Each is 149.16 ft (45.46 m) long and 12.17 ft (3.71 m) in diameter. Each SRB weighed approximately 1,300,000 lb (590 t) at launch. The two SRBs constituted about 69% of the total lift-off mass. The primary propellants were ammonium perchlorate ( oxidizer ) and atomized aluminum powder ( fuel ), and
9724-521: The different aspects of the mission. The Accident Analysis Panel, chaired by Kutyna, used data from salvage operations and testing to determine the exact cause behind the accident. The Development and Production Panel, chaired by Sutter, investigated the hardware contractors and how they interacted with NASA. The Pre-Launch Activities Panel, chaired by Acheson, focused on the final assembly processes and pre-launch activities conducted at KSC. The Mission Planning and Operations Panel, chaired by Ride, investigated
9867-406: The disaster and its aftermath. Press interest in the disaster increased in the following days; the number of reporters at KSC increased from 535 on the day of the launch to 1,467 reporters three days later. In the aftermath of the accident, NASA was criticized for not making key personnel available to the press. In the absence of information, the press published articles suggesting the external tank
10010-403: The disaster, US politicians expressed concern that White House officials, including Chief of Staff Donald Regan and Communications Director Pat Buchanan , had pressured NASA to launch Challenger before the scheduled January 28 State of the Union address, because Reagan had planned to mention the launch in his remarks. In March 1986, the White House released a copy of the original State of
10153-542: The disaster, a system was implemented to allow the crew to escape in gliding flight , but this system would not have been usable to escape an explosion during ascent. Immediately after the disaster, the NASA Launch Recovery Director launched the two SRB recovery ships, MV Freedom Star and MV Liberty Star , to proceed to the impact area to recover debris, and requested the support of US military aircraft and ships. Owing to falling debris from
10296-409: The doors, shutting down telephone communications, and freezing computer terminals to collect data from them. The crew cabin, which was made of reinforced aluminum, separated in one piece from the rest of the orbiter. It then traveled in a ballistic arc , reaching the apogee of 65,000 feet (20 km) approximately 25 seconds after the explosion. At the time of separation, the maximum acceleration
10439-511: The engine ready indications from the SSMEs. The MPS start commands are issued by the onboard computers at T−6.6 seconds (staggered start engine three, engine two, engine one all approximately within 0.25 of a second), and the sequence monitors the thrust buildup of each engine. All three SSMEs must reach the required 90% thrust within three seconds; otherwise, an orderly shutdown is commanded and safing functions are initiated. Normal thrust buildup to
10582-474: The event one orbiter main bus failed. The nominal operating voltage was 28 ± 4 volts DC. There were two self-contained, independent Hydraulic Power Units (HPUs) on each SRB, used to actuate the thrust vector control (TVC) system. Each HPU consisted of an auxiliary power unit (APU), fuel supply module, hydraulic pump , hydraulic reservoir and hydraulic fluid manifold assembly. The APUs were fueled by hydrazine and generated mechanical shaft power to drive
10725-580: The evidence presented on the failure of the O-rings was inconclusive and that there was a substantial margin in the event of a failure or erosion. They stated that their decision was to proceed with the launch. Morton Thiokol leadership submitted a recommendation for launch, and the teleconference ended. Lawrence Mulloy, the NASA SRB project manager, called Arnold Aldrich, the NASA Mission Management Team Leader, to discuss
10868-535: The explosion, the RSO kept recovery forces from the impact area until 12:37 p.m. The size of the recovery operations increased to 12 aircraft and 8 ships by 7:00 p.m. Surface operations recovered debris from the orbiter and external tank. The surface recovery operations ended on February 7. On January 31, the US Navy was tasked with submarine recovery operations. The search efforts prioritized
11011-406: The field joint. The Space Shuttle main engines (SSMEs) were throttled down as scheduled for maximum dynamic pressure (max q) . During its ascent, the Space Shuttle encountered wind shear conditions beginning at T+37 , but they were within design limits of the vehicle and were countered by the guidance system. At T+58.788 , a tracking film camera captured the beginnings of a plume near
11154-473: The first time in April 1981, and was used to conduct in-orbit research, and deploy commercial, military, and scientific payloads. At launch, it consisted of the orbiter , which contained the crew and payload, the external tank (ET), and the two solid rocket boosters (SRBs). The orbiter was a reusable, winged vehicle that launched vertically and landed as a glider. Five orbiters were built during
11297-401: The flight deck aboard the orbiter), as the flight reference computers translate navigation commands (steering to a particular waypoint in space, and at a particular time) into engine and motor nozzle gimbal commands, which orient the vehicle about its center of mass. As the forces on the vehicle change due to propellant consumption, increasing speed, changes in aerodynamic drag, and other factors,
11440-476: The flight stack (orbiter, external tank, SRBs) over onto the external tank. That rotating moment is initially countered by the hold-bolts. Prior to release of the vehicle stack for liftoff, the SRBs must simultaneously ignite and pressurize their combustion chambers and exhaust nozzles to produce a thrust-derived, net counter-rotating moment exactly equal to the SSME's rotating moment. With the SRBs reaching full thrust,
11583-442: The following year. The Space Shuttle mission, named STS-51-L , was the twenty-fifth Space Shuttle flight and the tenth flight of Challenger . The crew was announced on January 27, 1985, and was commanded by Dick Scobee . Michael Smith was assigned as the pilot, and the mission specialists were Ellison Onizuka , Judith Resnik , and Ronald McNair . The two payload specialists were Gregory Jarvis , who
11726-407: The force to expel (positive expulsion) the fuel from the tank to the fuel distribution line, maintaining a positive fuel supply to the APU throughout its operation. In the APU, a fuel pump boosted the hydrazine pressure and fed it to a gas generator. The gas generator catalytically decomposed the hydrazine into hot, high-pressure gas; a two-stage turbine converted this into mechanical power, driving
11869-508: The funding for the Space Shuttle program, reviewed the findings of the Rogers Commission as part of its investigation. The committee agreed with the Rogers Commission that the failed SRB field joint was the cause of the accident, and that NASA and Morton Thiokol failed to act despite numerous warnings of the potential dangers of the SRB. The committee's report further emphasized safety considerations of other components and recommended
12012-411: The ground launch sequence is terminated. Timing sequence referencing in ignition is critical for a successful liftoff and ascent flight. The explosive hold-down bolts relieve (through the launch support pedestals and pad structure) the asymmetric vehicle dynamic loads caused by the SSME ignition and thrust buildup, and applied thrust bearing loads. Without the hold-down bolts the SSMEs would violently tip
12155-430: The hold-down bolts are blown, releasing the vehicle stack, the net rotating moment is zero, and the net vehicle thrust (opposing gravity) is positive, lifting the orbiter stack vertically from the launch pedestal, controllable through the coordinated gimbal movements of the SSMEs and the SRB exhaust nozzles. During ascent, multiple all-axis accelerometers detect and report the vehicle's flight and orientation (referencing
12298-402: The hold-down stud. The stud traveled downward because of the release of tension in the stud (pretensioned before launch), NSD gas pressure and gravity. The stud was stopped by the stud deceleration stand, which contained sand. The hold-down stud was 28 in (710 mm) long and 3.5 in (89 mm) in diameter. The frangible nut was captured in a blast container mounted on the aft skirt of
12441-401: The initial explosion but was extensively damaged when it impacted the ocean. The remains of the crew were badly damaged from impact and submersion, and were not intact bodies. The USS Preserver made multiple trips to return debris and remains to port, and continued crew compartment recovery until April 4. During the recovery of the remains of the crew, Jarvis's body floated away and
12584-433: The initial search for debris and covered 486 square nautical miles (1,670 km ) at water depths between 70 feet (21 m) and 1,200 feet (370 m). The sonar operations discovered 881 potential locations for debris, of which 187 pieces were later confirmed to be from the orbiter. The debris from the SRBs was widely distributed due to the detonation of their linear shaped charges. The identification of SRB material
12727-450: The joint and burned through the aft attachment strut connecting it to the external propellant tank (ET), then into the tank itself. The collapse of the ET's internal structures and the rotation of the SRB that followed threw the shuttle stack, traveling at a speed of Mach 1.92, into a direction that allowed aerodynamic forces to tear the orbiter apart. Both SRBs detached from the now-destroyed ET and continued to fly uncontrollably until
12870-441: The joint had prevented the O-rings from creating a seal. Rainfall from the preceding time on the launchpad had likely accumulated within the field joint, further compromising the sealing capability of the O-rings. As a result, hot gas was able to travel past the O-rings and erode them. Molten aluminum oxides from the burned propellant resealed the joint and created a temporary barrier against further hot gas and flame escaping through
13013-468: The launch decision and weather concerns, but did not mention the O-ring discussion; the two agreed to proceed with the launch. An overnight measurement taken by the KSC Ice Team recorded the left SRB was 25 °F (−4 °C) and the right SRB was 8 °F (−13 °C). These measurements were recorded for engineering data and not reported, because the temperature of the SRBs was not part of
13156-479: The manufacturer and then shipped to Kennedy Space Center by rail for final assembly. The segments were fixed together using circumferential tang, clevis, and clevis pin fastening, and sealed with O-rings (originally two, changed to three after the Challenger Disaster in 1986) and heat-resistant putty. Each solid rocket booster had four hold-down posts that fit into corresponding support posts on
13299-411: The mobile launcher platform. Hold-down studs held the SRB and launcher platform posts together. Each stud had a nut at each end, the top one being a frangible nut . The top nut contained two explosive charges initiated by NASA standard detonators (NSDs), which were ignited at solid rocket motor ignition commands. When the two NSDs were ignited at each hold down, the frangible nut fractured, releasing
13442-498: The most powerful single- combustion chamber liquid-propellant rocket engine ever flown, the Rocketdyne F-1 . With a combined mass of about 1,180 t (1,160 long tons; 1,300 short tons), they comprised over half the mass of the Shuttle stack at liftoff. The motor segments of the SRBs were manufactured by Thiokol of Brigham City, Utah , which was later purchased by ATK . The prime contractor for most other components of
13585-467: The nozzle at water splashdown and prevent damage to the nozzle flexible bearing. Each SRB contained three rate gyro assemblies (RGAs), with each RGA containing one pitch and one yaw gyro. These provided an output proportional to angular rates about the pitch and yaw axes to the orbiter computers and guidance, navigation and control system during first-stage ascent flight in conjunction with the orbiter roll rate gyros until SRB separation. At SRB separation,
13728-432: The nozzle rock and tilt servoactuators . The HPU controller electronics were located in the SRB aft integrated electronic assemblies (IEAs ) on the aft external tank attach rings. The HPUs and their fuel systems were isolated from each other. Each fuel supply module (tank) contained 22 lb (10.0 kg) of hydrazine. The fuel tank was pressurized with gaseous nitrogen at 400 psi (2.8 MPa ), which provided
13871-417: The nozzle to control the direction of thrust. The four servovalves operating each actuator provided a force-summed majority-voting arrangement to position the power spool. With four identical commands to the four servovalves, the actuator force-sum action prevented, instantaneously, a single erroneous input affecting power ram motion. If differential-pressure sensing detected the erroneous input persisting over
14014-414: The ocean surface at 207 mph (333 km/h) approximately two minutes and 45 seconds after breakup. The estimated deceleration was 200 g , far exceeding structural limits of the crew compartment or crew survivability levels. The mid-deck floor had not suffered buckling or tearing, as would result from a rapid decompression, but stowed equipment showed damage consistent with decompression, and debris
14157-401: The orbiter, were concerned that ice would be violently thrown during launch and could potentially damage the orbiter's thermal protection system or be aspirated into one of the engines. Rocco Petrone , the head of Rockwell's space transportation division, and his team determined that the potential damage from ice made the mission unsafe to fly. Arnold Aldrich consulted with engineers at KSC and
14300-424: The planning that went into mission development, along with potential concerns over crew safety and pressure to adhere to a schedule. Over a period of four months, the commission interviewed over 160 individuals, held at least 35 investigative sessions, and involved more than 6,000 NASA employees, contractors, and support personnel. The commission published its report on June 6, 1986. The commission determined that
14443-418: The potential danger with the SRB field joints. It noted that NASA accepted the risk of O-ring erosion without evaluating how it could potentially affect the safety of a mission. The commission concluded that the safety culture and management structure at NASA were insufficient to properly report, analyze, and prevent flight issues. It stated that the pressure to increase the rate of flights negatively affected
14586-740: The potential dangers of the cold-weather launch. Boisjoly contested this assertion and stated that the data presented by Tufte were not as simple or available as Tufte stated. The Presidential Commission on the Space Shuttle Challenger Accident, also known as the Rogers Commission after its chairman, was formed on February 6. Its members were Chairman William P. Rogers , Vice Chairman Neil Armstrong , David Acheson , Eugene Covert , Richard Feynman , Robert Hotz, Donald Kutyna , Sally Ride , Robert Rummel, Joseph Sutter , Arthur Walker , Albert Wheelon, and Chuck Yeager . The commission held hearings that discussed
14729-406: The program's development, but he argued that multiple components, including the avionics and SSMEs in addition to the SRBs, were more dangerous and accident-prone than original NASA estimates had indicated. The US House Committee on Science and Technology conducted an investigation of the Challenger disaster and released a report on October 29, 1986. The committee, which had authorized
14872-477: The range during the Challenger disaster ). Over 5,000 parts were refurbished for reuse after each flight. The final set of SRBs that launched STS-135 included parts that had flown on 59 previous missions, including STS-1 . Recovery also allowed post-flight examination of the boosters, identification of anomalies, and incremental design improvements. The two reusable SRBs provided the main thrust to lift
15015-542: The range safety system cross-strap wiring connecting each SRB Range Safety System (RSS) and the ET RSS with each other. The aft attachment points consist of three separate struts: upper, diagonal and lower. Each strut contains one bolt with an NSD pressure cartridge at each end. The upper strut also carries the umbilical interface between its SRB and the external tank and on to the orbiter. There are four booster separation motors (BSMs) on each end of each SRB. The BSMs separate
15158-512: The recovery of the right SRB, followed by the crew compartment, and then the remaining payload, orbiter pieces, and ET. The search for debris formally began on February 8 with the rescue and salvage ship USS Preserver , and eventually grew to sixteen ships, of which three were managed by NASA, four by the US Navy , one by the US Air Force and eight by independent contractors. The surface ships used side-scan sonar to make
15301-415: The redundant NSDs to fire through a thin barrier seal down a flame tunnel. This ignites a pyro. booster charge, which is retained in the safe and arm device behind a perforated plate. The booster charge ignites the propellant in the igniter initiator; and combustion products of this propellant ignite the solid rocket motor initiator, which fires down the entire vertical length of the solid rocket motor igniting
15444-442: The required 90% thrust level will result in the SSMEs being commanded to the lift off position at T−3 seconds as well as the fire 1 command being issued to arm the SRBs. At T−3 seconds, the vehicle base bending load modes are allowed to initialize (referred to as the "twang", movement of approximately 25.5 in (650 mm) measured at the tip of the external tank, with movement towards the external tank). The fire 2 commands cause
15587-462: The right SRB. A leak had begun in the liquid hydrogen (LH2) tank of the ET at T+64.660 , as indicated by the changing shape of the plume. The SSMEs pivoted to compensate for the booster burn-through, which was creating an unexpected thrust on the vehicle. The pressure in the external LH2 tank began to drop at T+66.764 indicating that the flame had burned from the SRB into the tank. The crew and flight controllers made no indication they were aware of
15730-404: The safety of the launch. Morton Thiokol engineers expressed their concerns about the effect of low temperatures on the resilience of the rubber O-rings. As the colder temperatures lowered the elasticity of the rubber O-rings, the engineers feared that the O-rings would not be extruded to form a seal at the time of launch. The engineers argued that they did not have enough data to determine whether
15873-606: The scheduled launch time of 9:38 a.m. Based upon O-ring erosion that had occurred in warmer launches, Morton Thiokol engineers were concerned over the effect the record-cold temperatures would have on the seal provided by the SRB O-rings for the launch. Cecil Houston, the manager of the KSC office of the Marshall Space Flight Center, set up a conference call on the evening of January 27 to discuss
16016-474: The secondary O-ring could not provide a backup to the primary O-ring, as it would not necessarily form a seal in the event of joint rotation. The O-rings were redesignated as Criticality 1, removing the "R" to indicate it was no longer considered a redundant system. The first occurrence of in-flight O-ring erosion occurred on the right SRB on STS-2 in November 1981. In August 1984,
16159-495: The shuttle off the launch pad and up to an altitude of about 150,000 ft (28 mi; 46 km). While on the pad, the two SRBs carried the entire weight of the external tank and orbiter and transmitted the weight load through their structure to the mobile launcher platform . Each booster had a liftoff thrust of approximately 2,800,000 pounds-force (12 MN ) at sea level, increasing shortly after liftoff to about 3,300,000 lbf (15 MN). They were ignited after
16302-406: The simulated internal pressure of a launch. Joint rotation, which occurred when the tang and clevis bent away from each other, reduced the pressure on the O-rings, which weakened their seals and made it possible for combustion gases to erode the O-rings. NASA engineers suggested that the field joints should be redesigned to include shims around the O-rings, but they received no response. In 1980,
16445-510: The situation. Obviously a major malfunction. We have no downlink." Soon afterwards, he said, "We have a report from the Flight Dynamics Officer that the vehicle has exploded. The flight director confirms that. We are looking at checking with the recovery forces to see what can be done at this point." In Mission Control, flight director Jay Greene ordered that contingency procedures be put into effect, which included locking
16588-418: The solid rocket motor propellant along its entire surface area instantaneously. At T−0, the two SRBs are ignited, under command of the four onboard computers; separation of the four explosive bolts on each SRB is initiated; the two T-0 umbilicals (one on each side of the spacecraft) are retracted; the onboard master timing unit, event timer and mission event timers are started; the three SSMEs are at 100%; and
16731-435: The soot between the O-rings resulted from non-uniform pressure at the time of ignition. The January 1985 launch of STS-51-C was the coldest Space Shuttle launch to date. The air temperature was 62 °F (17 °C) at the time of launch, and the calculated O-ring temperature was 53 °F (12 °C). Post-flight analysis revealed erosion in primary O-rings in both SRBs. Morton Thiokol engineers determined that
16874-441: The switch could be moved. Later tests established that neither the force of the explosion nor the impact with the ocean could have moved them, indicating that Smith made the switch changes, presumably in a futile attempt to restore electrical power to the cockpit after the crew cabin detached from the rest of the orbiter. On July 28, 1986, NASA's Associate Administrator for Space Flight, former astronaut Richard H. Truly , released
17017-495: The switching valve closed when the valve was in the secondary position. When the valve was closed, a signal was sent to the APU controller, that inhibited the 100% APU speed control logic and enabled the 112% APU speed control logic. The 100-percent APU speed enabled one APU/HPU to supply sufficient operating hydraulic pressure to both servoactuators of that SRB. The APU 100-percent speed corresponded to 72,000 rpm, 110% to 79,200 rpm, and 112% to 80,640 rpm. The hydraulic pump speed
17160-468: The terms solid rocket motor and solid rocket booster are often used interchangeably, in technical use they have specific meanings. The term solid rocket motor applied to the propellant, case, igniter and nozzle. Solid rocket booster applied to the entire rocket assembly, which included the rocket motor as well as the recovery parachutes, electronic instrumentation, separation rockets, range safety destruct system, and thrust vector control. Each booster
17303-448: The three RS-25 main engines' thrust level was verified. Seventy-five seconds after SRB separation, SRB apogee occurred at an altitude of approximately 220,000 ft (42 mi; 67 km); parachutes were then deployed and impact occurred in the ocean approximately 122 nautical miles (226 km ) downrange, after which the two SRBs were recovered. The SRBs helped take the Space Shuttle to an altitude of 28 miles (45 km) and
17446-507: The total propellant for each solid rocket motor weighed approximately 1,100,000 lb (500 t) (see § Propellant ). The inert weight of each SRB was approximately 200,000 pounds (91 t). Primary elements of each booster were the motor (including case, propellant, igniter, and nozzle ), structure, separation systems, operational flight instrumentation, recovery avionics, pyrotechnics , deceleration system, thrust vector control system, and range safety destruct system. While
17589-412: The two smaller, aft-mounted Orbital Maneuvering System (OMS) engines. When it launched, the orbiter was connected to the ET , which held the fuel for the SSMEs. The ET consisted of a larger tank for liquid hydrogen (LH2) and a smaller tank for liquid oxygen (LOX), both of which were required for the SSMEs to operate. After its fuel had been expended, the ET separated from the orbiter and reentered
17732-463: The vehicle and flight anomalies. At T+68 , the CAPCOM , Richard O. Covey , told the crew, " Challenger , go at throttle up," indicating that the SSMEs had throttled up to 104% thrust. In response to Covey, Scobee said, "Roger, go at throttle up"; this was the last communication from Challenger on the air-to-ground loop. At T+72.284 , the right SRB pulled away from the aft strut that attached it to
17875-404: The vehicle automatically adjusts its orientation in response to its dynamic control command inputs. The SRBs are jettisoned from the space shuttle at an altitude of about 146,000 ft (45 km). SRB separation is initiated when the three solid-rocket motor-chamber pressure transducers are processed in the redundancy-management middle-value select and the head-end chamber pressure of both SRBs
18018-502: The vehicle in all three axes (roll, pitch, and yaw). The ascent thrust vector control portion of the flight control system directed the thrust of the three shuttle main engines and the two SRB nozzles to control shuttle attitude and trajectory during lift-off and ascent. Commands from the guidance system were transmitted to the Ascent Thrust Vector Control (ATVC) drivers, which transmitted signals proportional to
18161-470: Was 3,600 rpm and supplied hydraulic pressure of 3,050 ± 50 psi (21.03 ± 0.34 MPa). A high pressure relief valve provided overpressure protection to the hydraulic system and relieved at 3,750 psi (25.9 MPa). The APUs/HPUs and hydraulic systems were reusable for 20 missions. Each SRB had two hydraulic gimbal servoactuators, to move the nozzle up/down and side-to-side. This provided thrust vectoring to help control
18304-732: Was a burst of static on the air-to-ground loop as the vehicle broke up, which was later attributed to ground-based radios searching for a signal from the destroyed spacecraft. NASA Public Affairs Officer Steve Nesbitt was initially unaware of the explosion and continued to read out flight information. At T+89 , after video of the explosion was seen in Mission Control , the Ground Control Officer reported "negative contact (and) loss of downlink " as they were no longer receiving transmissions from Challenger . Nesbitt stated, "Flight controllers here are looking very carefully at
18447-607: Was apparent that the ALS program was no longer required. The initial phase of the SDI would employ existing Titan IV and Atlas II rockets. The launch requirements for subsequent phases of the SDI deployment were too vague to allow the immediate ongoing direction of the ALS program and its associated costs. At the end of 1990, the ALS program, was changed to a propulsion development project with an annual budget of $ 150 million. Space Shuttle Challenger disaster On January 28, 1986,
18590-670: Was assigned to conduct research for the Hughes Aircraft Company , and Christa McAuliffe , who flew as part of the Teacher in Space Project . The primary mission of the Challenger crew was to use an Inertial Upper Stage (IUS) to deploy a Tracking and Data Relay Satellite (TDRS), named TDRS-B , that would have been part of a constellation to enable constant communication with orbiting spacecraft. The crew also planned to study Halley's Comet as it passed near
18733-508: Was attached to the external tank at the SRB's aft frame by two lateral sway braces and a diagonal attachment. The forward end of each SRB was attached to the external tank at the forward end of the SRB's forward skirt. On the launch pad, each booster also was attached to the mobile launcher platform at the aft skirt by four holddown studs, with frangible nuts that were severed at liftoff. The boosters were composed of seven individually manufactured steel segments. These were assembled in pairs by
18876-823: Was buried at the National Memorial Cemetery of the Pacific in Honolulu , Hawaii. McNair was buried in Rest Lawn Memorial Park in Lake City, South Carolina, but his remains were later moved within the town to the Dr. Ronald E. McNair Memorial Park. Resnik was cremated and her ashes were scattered over the water. McAuliffe was buried at Calvary Cemetery in Concord, New Hampshire . Jarvis
19019-573: Was charged with deploying the space based elements of the Strategic Defense Initiative (SDI) program. Secondly, the ALS program was to find a way to transport many thousands of tons of equipment for the SDI into low Earth orbit at a cost less than $ 1,000 per kilogram. The usual cost was about $ 10,000 per kg. The program had three main contractors, each with an $ 800 million multi-year contract. They were Boeing Aerospace, Martin-Marietta, and General Dynamics. The ALS program budget
19162-484: Was considered a redundant system due to the secondary O-ring. Evaluations of the proposed SRB design in the early 1970s and field joint testing showed that the wide tolerances between the mated parts allowed the O-rings to be extruded from their seats rather than compressed. This extrusion was judged to be acceptable by NASA and Morton Thiokol despite concerns of NASA's engineers. A 1977 test showed that up to 0.052 inches (1.3 mm) of joint rotation occurred during
19305-674: Was cremated, and his ashes were scattered in the Pacific Ocean . Unidentified crew remains were buried at the Space Shuttle Challenger Memorial in Arlington on May 20, 1986. President Ronald Reagan had been scheduled to give the 1986 State of the Union Address on January 28, 1986, the evening of the Challenger disaster. After a discussion with his aides, Reagan postponed
19448-432: Was embedded between the two forward windows that may have caused a loss of pressure. Impact damage to the crew cabin was severe enough that it could not be determined whether the crew cabin had previously been damaged enough to lose pressurization. Unlike other spacecraft, the Space Shuttle did not allow for crew escape during powered flight. Launch escape systems had been considered during development, but NASA's conclusion
19591-617: Was just under $ 2.5 billion. In 1989, the Bush administration , via the Defense Acquisition Board, was asked to ratify an existing plan to have the ALS program at an advanced state of development in 1990; ready for a first flight in 1998; and fully operational in 2000. Then, from 2000 to 2005, the ALS program would develop a modular family of launch vehicles , with a payload capacity to low Earth orbit ranging from 5,000 kilograms to 200,000 kilograms. However, by late 1989, it
19734-610: Was not located until April 15, several weeks after the other remains had been positively identified. Once remains were brought to port, pathologists from the Armed Forces Institute of Pathology worked to identify the human remains, but could not determine the exact cause of death for any of them. Medical examiners in Brevard County disputed the legality of transferring human remains to US military officials to conduct autopsies, and refused to issue
19877-457: Was primarily conducted by crewed submarines and submersibles. The vehicles were dispatched to investigate potential debris located during the search phase. Surface ships lifted the SRB debris with the help of technical divers and underwater remotely operated vehicles to attach the necessary slings to raise the debris with cranes. The solid propellant in the SRBs posed a risk, as it became more volatile after being submerged. Recovered portions of
20020-440: Was recovered from February 14 to 28, and post-recovery analysis produced results consistent with functional engines suddenly losing their LH2 fuel supply. Deepwater recovery operations continued until April 29, with smaller scale, shallow recovery operations continuing until August 29. On December 17, 1996, two pieces of the orbiter were found at Cocoa Beach . On November 10, 2022, NASA announced that
20163-459: Was that the Space Shuttle's expected high reliability would preclude the need for one. Modified SR-71 Blackbird ejection seats and full pressure suits were used for the two-person crews on the first four Space Shuttle orbital test flights, but they were disabled and later removed for the operational flights. Escape options for the operational flights were considered but not implemented due to their complexity, high cost, and heavy weight. After
20306-537: Was the 10th flight for the orbiter and the 25th flight of the Space Shuttle fleet. The crew was scheduled to deploy a communications satellite and study Halley's Comet while they were in orbit, in addition to taking schoolteacher Christa McAuliffe into space under the Teacher In Space program. The latter task resulted in a higher-than-usual media interest in and coverage of the mission; the launch and subsequent disaster were seen live in many schools across
20449-443: Was the cause of the explosion. Until 2010, CNN's live broadcast of the launch and disaster was the only known on-location video footage from within range of the launch site. Additional amateur and professional recordings have since become publicly available. The Challenger accident has been used as a case study for subjects such as engineering safety , the ethics of whistleblowing , communications and group decision-making, and
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