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Abort Guidance System
Auxiliary Power Unit
Abort to Orbit
Russian Micropurification Unit (Russian)
Carbon Dioxide Removal System
Colony Forming Unit
Control Moment Gyroscope
Cell Performance Monitor
Compound Specific Analyzer-Combustible Products
Extravehicular Mobility Unit
Electrical Power System
Fuel Cell Monitoring System
Functional Cargo Block (Russian)
Flight Safety Office
Galley Iodine Removal Assembly
Guidance, Navigation, and Control
General Purpose Computer
Global Positioning System
Inertial Measurement Unit
International Space Station
Internal Thermal Control System
Launch Control Officer
Low Iodine Residual System
Loss of Crew
Loss of Vehicle
Minimum Duration Flight
Master Events Controller
Main Landing Gear
Micro-Meteoroid Orbital Debris
Marshall Space Flight Center
NASA Standard Initiator
Office of Safety & Mission Assurance (NASA HQ)
Protuberance Air Load
Precision Approach Path Indicator
Primary Avionics Software System
Pyrotechnic Initiator Controller
Partial Pressure of CO2
Reaction Control System/Subsystem
Remote Manipulator System
Russia or Russian
Return to Launch Site
Safety & Mission Assurance
Solid Fuel Oxygen Generator
Solid Rocket Booster
Condensate Water Processor Unit (Russian)
Space Shuttle Main Engine
Space Shuttle Program
Thermal Protection System
Loss of Crew
Crew Injury/Illness and/or Loss of Vehicle or Mission
SpaceShipTwo, PF04 10/31/2014
STS-114, 115, 118, 119, 124, 126
STS-116 and STS-125
Progress M-12M 8/24/2011
Gemini 10 7/18/1966
Apollo 12 11/14/1969
Apollo 13 4/11/1970
Soyuz 18-1(18a) 4/5/1975
Other SRB gas seal anomalies:
STS-2, 6, 41B, 41C, 41D, 51C, 51D, 51B, 51G, 51F, 51I, 51J, 61A, 61B, 61C, 42, 70, 71, 78
STS-51L (Challenger) 1/28/1986
Soyuz TM-9 2/11/1990
SpaceShipTwo PF04 | 10/31/2014 | Crew: 2 | Loss of Crew (1)
Vehicle breakup during powered flight.
On October 31, 2014 shortly after separating from the WhiteKnightTwo carrier aircraft, the SpaceShipTwo vehicle broke apart resulting in the loss of one crew member. A National Transportation Safety Board investigation into the accident is ongoing.
SpaceShipOne 14P | 5/13/2004 | Crew: 1
Flight computer unresponsive. Recovered by rebooting.
On May 13, 2004 the flight computer on SpaceShipOne became unresponsive. During the boost following the vertical part of the trajectory, the avionics display flickered and went blank. The ground displays did not show an error. The avionics display on SpaceShipOne came back on as soon as the motor shut down.
Due to the loss of avionics during the boost, the trajectory was not precise. The avionics malfunction was traced to a dimmer, a small electrical component.
SpaceShipOne 16P | 9/29/2004 | Crew: 1
Uncommanded vehicle roll. Control regained prior to apogee.
On September 29, 2004 SpaceShipOne performed a series of 60 rolls during last stage of engine burn. SpaceShipOne coasted to 103 km of altitude and successfully completed the first of two X-Prize flights. The motor was shut down when the pilot noted that his altitude predictor exceeded the required 100 km mark. During the motor burn the spacecraft began to roll uncontrollably, but the pilot continued despite advice from the ground to shut the motor down and abort the attempt.
The thin air at that altitude meant that the control surfaces didn't have enough air flowing over them, so they lost effectiveness to compensate for the roll as the spacecraft pointed nearly straight up. The pilot needed to correct the rolling that occurred because of asymmetric thrust coming from the engine.
To correct the issue for the 17P flight, the amount of allowable “down pitch trim” was limited, to avoid the negative-lift condition. The solution was to more gently turn the corner, such that a forward correction later would not be needed. Pointing straight up at burnout was determined to be acceptable, as long as negative lift was not created. This problem was corrected on SpaceShipTwo.
Late Release Orbiter Tyvek Covers
During the ascent phase of:
STS-114 | 7/26/2005
STS-115 | 9/9/2006
STS-118 | 8/8/2007
STS-119 | 3/15/2009
STS-124 | 7/31/2008
STS-126 | 11/14/2008
The Tyvek covers for the reaction control system jets released later than intended. The late release resulted in the Tyvek reaching a higher velocity than designed, thus posing a higher risk of damage to the orbiter.
Tyvek covers were used to keep rain water and other debris out of the reaction control system jets while the shuttle was on the launch pad.
STS-116 | 12/10/2006 | Related or Recurring event
STS-125 | 5/11/2009 | Related or Recurring event
Debris from the flight vehicle or the launch facility poses a risk to all crewed space launches.
Other significant ascent debris events have occurred on:
On December 10, 2006, during ascent, booster trowelable ablative (BTA) around the solid rocket booster (SRB) left hand aft booster separation motor (BSM) nozzle liberated and was seen striking the bottom of the orbiter shortly after SRB separation began. The root cause of the observed debris liberation was determined to be stress buildup in the thermal protection system (TPS) and BTA closeout configuration at the aft BSM exit cone. The failure mechanism that produced the forward transport of the BTA was a hinging effect on the liberated BTA coupled with plume expansion at altitude, which projected the debris forward to where it struck the orbiter.
The BTA closeouts around the aft BSM nozzles were modified to eliminate the failure mechanism that caused the forward debris transport as well as limit the size and release angle of BTA liberated at SRB separation.
On May 11, 2009 during ascent the Wing Leading Edge Impact Detection System (WLEIDS) recorded two impacts on the starboard chine, which was confirmed by video imagery analysis.
Damage detected during on-orbit inspection was below the damage tolerance threshold.
STS-95 | 10/29/1998 | Crew: 7 | Related or Recurring event
Drag chute door separated during launch and impacted main engine bell.
On October 29, 1998 during the main engine ignition sequence, the drag chute panel fell away from the vehicle. Video of the launch confirmed the drag chute door detached three seconds prior to liftoff and hit the engine nozzle of Space Shuttle Main Engine (SSME) 1.
The remains of the door were found during a post-launch pad inspection, revealing that at least one aluminum shear pin used to attach the door sheared. The root cause of the shearing was a combination of the high pressure environment caused by SSME ignition and a low margin hinge pin. The drag chute door struck the nozzle of the center main engine but did not do any appreciable damage to the engine or vehicle. Concerns about the status and condition of the chute contained in the drag chute compartment resulted in the decision not to deploy the chute during landing.
As a precautionary measure, two subsequent missions used a solid closeout panel bolted over the drag chute compartment and did not utilize the drag chute. All flights following these missions used Inconel instead of aluminum as shear pin material.
STS-124 | 5/31/2008 | Crew: 7 | Related or Recurring event
Pad 39-A flame trench suffered significant damage causing about 3,500 refractory bricks to be blown away from the flame trench wall.
On May 31, 2008 during the launch of STS-124, the Pad 39-A flame trench suffered significant damage causing about 3,500 refractory bricks to be blown away from the flame trench wall. The bricks scattered away from the flame trench beyond the pad perimeter fence. This debris could have damaged the vehicle or the launch complex.
Pad generated debris is a concern for any spaceflight, due to the potential for debris to travel in a manner that can damage the vehicle or the launch complex.
STS-93 | 7/23/1999 | Crew: 5
At T+5 a short on AC1 Phase A resulted in loss of SSME1 Controller A and SSME3 Controller B.
SSME3 H2 leak: early LOX depletion and shutdown.
STS-93 encountered two close-call events.
STS-114 | 5/26/2006 | Crew: 7
Bird strike on External Tank.
Loss of foam from External Tank PAL ramp.
TPS gap filers protruding. Removed during third mission EVA.
Missing O-ring resulted in ejection of one of two NSIs, compromising the ET forward
separation bolt function and damaging secondary structure and a thermal blanket.
STS-114 encountered four close-call events.
STS-117 | 6/8/2007 | Crew: 7
Thermal blanket damage. EVA performed to repair damage.
On June 8, 2007 during ascent, a thermal blanket covering the port orbital maneuvering system (OMS) pod was damaged.
An unplanned extravehicular activity, a high risk operation, was performed to repair the damaged blanket, so the blanket could effectively prevent potential damage to the vehicle from heating during entry. Failure of the thermal protection during entry could have resulted in overheating of the OMS and catastrophic structural failure of the vehicle and loss of crew.
The blanket was repaired by inserting pins between the thermal blanket and the surrounding shuttle tiles. A surgical stapler was also used in fastening the two thermal blankets together.
Progress M-12M | 8/24/2011 | Crew: 0 | Loss of Mission
Anomaly in fuel pressurization system led to shutdown of 3rd stage engine. Vehicle failed to reach orbit.
On the August 24, 2011 flight of Progress M-12M (44P) an anomaly in the fuel pressurization system led to the shutdown of the third stage engine. The engine shutdown resulted in the vehicle failing to reach orbit and crashing in the Altai Mountains.
A root cause has yet to be conclusively determined. A blockage of the third stage fuel lines is believed to be the leading cause due to manufacturing and processing.
Progress is an uncrewed vehicle which uses the same third stage rocket segment as the crewed Soyuz capsule.
Gemini 10 | 7/18/1966 | Crew: 2
1st stage oxidizer tank exploded at staging. No discernible effects. Nominal ascent.
On July 18, 1966, 1.2 seconds after booster engine cutoff, tracking cameras displayed an amber cloud and an unusual amount of debris. The evidence indicated the first stage oxidizer tank ruptured after the normal staging sequence.
This event had no detectable effect on the operation of the second stage.
Apollo 12 | 11/14/1969 | Crew: 3
Lightning strike on ascent.
During the Apollo 12 launch on November 14, 1969 lightning struck the spacecraft.
Light rain was falling, but weather conditions did not indicate any thunderstorm activity. There were seven miles of visibility with cloud break estimated at 800 feet and overcast conditions at 10,000 feet.
At 11:22am, T+36 seconds, the crew saw a bright light.
At T+36.5 seconds many errors occurred: Fuel Cells 1, 2, and 3 disconnected; Main Buses A and B were under-voltage; Alternating Current (AC) Buses 1 and 2 overloaded. The warning lights and alarm came on in the cabin, indicating failure of the Inertial Stabilization System.
At T+52 seconds (13,000 feet) lightning struck the vehicle and the Inertial Measurement Unit platform tumbled.
The potential effect on the vehicle was induction into wiring, depending on the location and rate of change of potential and direct current flow in grounding. The high negative voltage spike (delta voltage/delta time) caused the Silicon Controlled Rectifiers to trip on the Fuel Cell and AC Inverter overload sensors. Failures occurred in four Service Module Reaction Control System helium tank quantity measurements, five thermocouples, and four pressure/temperature transducers.
Using power from the Battery Relay Bus, the crew reconnected the Fuel Cells to Main Bus A and B, and reconnected the inverters to AC Bus 1 and 2. The mission continued.
Apollo 13 | 4/11/1970 | Crew: 3
2nd stage center engine shutdown due to pogo oscillations.
During the April 11, 1970 launch of Apollo 13 severe pogo oscillations were experienced. Acceleration at the engine attachment reached an estimated 34 g (the accelerometer went out of recordable range) before the engine's combustion chamber low-level pressure sensor commanded an engine shutdown.
Soyuz 18-1(18a) | 4/5/1975 | Crew: 2 | Loss of Vehicle/Mission
Electrical fault caused premature firing of half of the 2nd stage separation bolts, resulting in the inability to fire the remaining ones. Staging failure resulted in abort sequence being used at T=295 seconds.
During ascent on April 5, 1975 an electrical malfunction in the Soyuz booster prematurely fired two of the four explosive latches holding the core of the first and second stage together. This severed the electrical connections necessary for firing the remaining two latches. When the core first stage burned out, it could not be cast off as designed.
Ignition of the second stage occurred normally, but the booster was rapidly dragged off course by the weight of the depleted core first stage. When the course deviation reached 10 degrees, the automatic safety system activated, shutting down the booster and separating the Soyuz capsule from the launch vehicle. At the time of separation, the Soyuz was 180 km high and traveling at 5.5 km per second.
The crew endured a 20+ g re-entry and landed in the Altai Mountains. The capsule rolled down a mountain side, and was caught in bushes just short of a precipice. After an hour of waiting in the cold next to the capsule, the crew was discovered by locals speaking Russian.
One crew member suffered internal injuries from the high-g re-entry and downhill fall and never flew again.
STS-51F | 7/29/1985 | Crew: 7 | Abort to Orbit
Temperature sensor problems resulted in SSME1 shutdown at T+5:45.
On July 29, 1985 at T+5:43, both temperature sensors for the Space Shuttle Main Engine (SSME) 1 high pressure fuel turbopump showed readings exceeding the redline limit. This resulted in a premature shutdown of SSME 1 and declaration of an Abort to Orbit condition, the first in program history. At T+8:13, one of the two temperature sensors on SSME 3 indicted a high reading, but auto-shutdown was inhibited to assure STS-51F achieved an acceptable orbit.
These events were a result of confirmed instrumentation failures. The temperature sensors were removed for engineering analysis following the flight, and a new configuration sensor was used on subsequent engines.
Other SRB Seal Events | Related or Recurring event
SRB gas sealing anomalies have also occurred on:
STS-2 November 12, 1981
STS-6 April 4, 1983
STS-11 (STS-41B) February 3,1984
STS-41C April 6,1984
STS-41D August 30, 1984
STS-51C January 24,1985
STS-51D April 12, 1985
STS-51B April 29, 1985
STS-51G June 17,1985
STS-51F July 29, 1985
STS-51I August 27, 1985
STS-51J October 3, 1985
STS-61A October 30, 1985
STS-61B November 26,1985
STS-61C January 12, 1986
STS-42 January 22, 1992
STS-71 June 27, 1995
STS-70 July 13, 1995
STS-78 June 20, 1996
STS-51L (Challenger) | 1/28/1986 | Crew: 7 | Loss of Crew | Related or Recurring event
SRB seal failure.
On January 28, 1986 a combustion gas leak developed in the right solid rocket motor aft field joint shortly after solid rocket booster ignition. The resulting hot gas plume exiting the joint impinged upon the SRB lower attachment strut and adjacent external tank structure weakening the structure to the point of failure.
Seventy-four seconds into flight, the Space Shuttle Challenger broke up.
All seven crew members were lost.
Soyuz TM-9 | 2/11/1990 | Crew: 2
DM insulation torn loose on ascent; contingency EVA repair.
During the docking of Soyuz TM-9 on February 11, 1990, the TM-8 crew aboard Mir noticed three of the eight descent module's thermal blankets had partially detached near the heat shield during ascent. This raised five concerns:
A rescue mission with a cosmonaut aboard Soyuz-TM 10 was considered, but not executed. The temperature of TM-9 was stabilized by the Mir directing it into alignment with the sun.
Four months later, the Kristall module (90-048A) arrived with the special tools needed to repair the decent module. Cosmonauts were able to secure the blankets out of the sensor's line of sight after an EVA longer than seven hours. The success of the EVA led to a nominal entry upon mission completion.
STS-91 | 6/2/1998 | Crew: 6
Main engine pressure chamber sensor failed. If it occurred later, logic error may have triggered at RTLS.
After the launch of STS-91 on June 2, 1998, a channel A main engine pressure chamber sensor froze. The sensor was disqualified by engine control software when the sensor exceeded allowable limits during the max Q engine throttle down sequence however the sensor remained qualified for engine redline monitoring since the reading was still within reasonableness limits / operational range for the sensor. The channel B sensor and the main engine performed nominally throughout ascent. If an engine problem had occurred, the channel B sensor would have displayed the correct information and indicated the proper corrective action. However, the channel B sensor would have been ignored due to the frozen channel A sensor.
The post-flight inspection revealed that contamination from a seal leak check caused the sensor to freeze. Marshall Space Flight Center (MSFC) project engineering suggested adding a V-seal leak check prior to the acceptance test, to ensure the newly added V-seal was installed properly. However, MSFC project engineering was unaware that performing the leak check would require the manufacturing personnel to plug the chamber pressure port with Viton. After the flight, the sensor was still plugged with a piece of Viton.
If the main engine pressure chamber sensor froze later in the flight, logic errors may have triggered a premature engine shutdown and a return to the launch site abort. Post-flight software changes were implemented to prevent this from occurring on subsequent flights. Additionally, a one-time flow check verified the reliability of the Lee-Jet for all engines in the fleet. A corrective action requires post-Lee-Jet installation flow check and borescope inspection for future engine builds. Lastly, the V-seal leak check was eliminated in future engine builds.
STS-110 | 4/8/2002 | Crew: 7
STS-109 | 3/1/2002 | Crew: 7
STS-108 | 12/5/2001 | Crew: 7
Incorrect adjustments to the controller software resulted in SSME underperformance.
Prior to STS-108 a change had been made to the controller software coefficient for the Space Shuttle Main Engine (SSME) to compensate for an observed measurement bias in the SSME main combustion chamber pressure sensor, which controls the SSME fuel/oxidizer mixture ratio. The pressure chamber sensor was biased high causing the flight software to lower the chamber pressure by decreasing the liquid oxygen flow rate. To correct the high bias a coefficient in the equation was adjusted to compensate. Because of communication errors between ground systems engineers and deficiencies in the flight software verification and validation processes, the software coefficient was adjusted in the wrong direction, resulting in even larger dispersions in the mixture ratio and SSME performance.
The error in the coefficient was discovered during post-flight reconstruction of the data from STS-108. The cause of the error remained unknown until after STS-110. The erroneous coefficient was flown on three consecutive flights (STS-108, STS-109, and STS-110) resulting in a slight SSME underperformance on each flight, and was fixed with the proper coefficient and independent verification prior to STS-111. The error in software and resulting mixture ratio wasn't severe enough to cause any significant impacts to SSME performance, and all three flights achieved proper orbits. However, if the software error had been larger, more severe impacts to the missions and crew safety could have occurred, including a premature engine shutdown/failure resulting in on-pad or ascent abort, loss of mission.
Other significant ascent debris events have occurred on:
Late Release Orbiter Tyvek Covers
SRB Seal Events (1981-96)
Related or Recurring event
LANDING & POSTLANDING