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2

The contingency was declared at 2:15:19.160 a.m. PST. No collateral damage or injury 

was reported as a result of this mishap. No physical launch vehicle or spacecraft debris 

was available for examination. The cost of the mission was approximately $388 million. 

A NASA-led Taurus XL T9 Mission Glory Mishap Investigation Board (MIB) was formed 

by Mr. William Gerstenmaier, Associate Administrator for NASA's Space Operations 

Mission Directorate, March 8, 2011. The MIB was chaired by Mr. Bradley Flick, Director 

for Research and Engineering at NASA's Dryden Flight Research Center. 

The Taurus XL Mission T9 MIB was commissioned to: 

 Obtain and analyze whatever evidence, facts, and opinions it considers relevant. 

 Conduct tests and any other activity it deems appropriate. 

 Interview witnesses and receive statements from witnesses. 

 Impound property, equipment, and records as considered necessary. 

 Determine the proximate cause(s), root cause(s), and contributing factors related 

to the mishap. 

 Develop recommendations to prevent similar mishaps. 

 Provide a final written report. 

No physical evidence from the T9 mishap was available for examination. The T9 MIB 

tested hardware, performed engineering simulations, analyzed simulation data, and 

reviewed telemetry data (including telemetry obtained after the T8 mishap). The MIB 

also obtained technical knowledge on the Taurus XL launch vehicle using information 

and evidence gathered from interviews, technical interchange meetings, and document 

and data reviews with the NASA Launch Services Program; NASA's Glory Project; 

Orbital’s Dulles, Virginia, and Chandler, Arizona Divisions; and Ensign-Bickford 

Aerospace and Defense Company, the manufacturer of the fairing frangible joint 

assembly. It was from these sources that the T9 MIB then developed the fault, event, 

and causal factor trees. 

Using this data, the MIB was able to analyze and determine that the proximate cause of 

the mishap was the failure of the payload fairing system to separate. Detailed analysis 

determined one of the side rails of the payload fairing system failed to fully fracture near 

the fairing’s nose cap. However, no root cause for the fairing’s failure to separate was 

able to be determined. The board also analyzed telemetry comparing the T8 telemetry 

data with T9 telemetry data and concluded that the post-fairing separation failure 

configurations of both vehicles were similar. 

NASA has completed the Agency’s assessment of the Glory T9 MIB report. NASA is not 

making the report public because it contains information the company considers to be 

proprietary and information restricted by International Traffic in Arms Regulations. 

Instead, NASA is providing this overview of the mishap and the investigating board's 

findings and recommendations regarding the Glory mishap. 
BACKG

Mission

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n Overview

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service was

n October 2

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arth's atmos

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ord. 

alance and 

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elation with

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2003. 

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sphere as a

Earth's atm

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as the total s

launch into 

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tion in a 438

ory’s data w

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A's Goddar

The spacecr

f the Glory S

under the s

ime lifetime

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mosphere to

fects requir

solar irradia

low Earth o

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8-mile altitu

would have

instrument

perations p

rd Space F

raft was bu

Spacecraft 

small expen

e, was inten

rties of natu

imate chan

o determine

res measur

ance. Glory

orbit as par

ain is a seri

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ts located o

period was 

light Cente

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5

The 63-inch payload fairing system was used on both Orbiting Carbon Observatory 

(OCO) and Glory missions. The Glory Taurus XL T9 mission was the first Taurus launch 

following the failed OCO Taurus XL T8 launch. Like the Glory T9 mission, the OCO T8 

mission failed to deliver its payload to orbit because of the failure of the payload fairing 

to separate. The OCO T8 mishap investigation could not identify a root cause but did 

identify four potential intermediate causes: 

1. Failure of the base ring frangible joint to completely fracture. 

2. Failure of the electrical subsystem preventing ordnance from firing. 

3. Failure of the fairing’s hot gas generator pneumatic system to 

pressurize resulting in a failure to push the fairing halves and/or side rails 

apart. 

4. Snagging of the flexible confined detonating cord (FCDC) on one of the 

payload fairing side rail’s nut plate. 

A Taurus XL Return-To-Flight activity took corrective actions against these potential 

causes for the T9 Taurus XL flight, including replacement of the hot gas generator 

pneumatic system with a cold gas system (with added pressure sensor telemetry to 

verify thruster activation), and installation of room temperature vulcanizing silicone to 

eliminate the potential for FCDC snagging. 

During a normal flight separation, a pneumatic system would pressurize the fairing 

deployment thrusters. The fairing’s frangible joints (both side rails and the base ring) 

would be broken using MDF, and the thrusters then would push the fairing halves 

outward on external hinges and separate the fairing halves from the stage. Sensors 

mounted in the fairing would provide telemetry on temperature, pressure, and acoustic 

environments. The fairing base ring has separation break wires on each half and is 

monitored in telemetry. 

MISHAP CAUSES AND RECOMMENDATIONS 

Using information and evidence gathered from interviews, technical interchange 

meetings, documents, data reviews, and testing, the T9 MIB developed a timeline of 

events, performed a detailed Fault Tree Analysis, and a Root Cause Analysis. From 

these analyses, the T9 MIB identified the proximate cause and possible intermediate 

causes for the failure. As a matter of explanation, a proximate cause, also known as 

the direct cause, is the event or condition that directly resulted in the occurrence of an 

undesired outcome. In this case, the proximate cause was that the fairing did not 

separate from the launch vehicle. An intermediate cause is an event or condition that 

created the proximate cause and that if eliminated or modified would have prevented 

the proximate cause from occurring. 
6

Proximate Cause: Fairing separation failed 

Flight telemetry data strongly suggested that the payload fairing did not separate as 

planned. The T9 MIB hesitated to declare this as the sole and obvious proximate cause 

and, instead, elected to conduct a comprehensive investigation of potential causes. 

Comparison of modeled structural behavior based on analysis and ground test to flight 

data provided through telemetry showed the only reasonable scenario was that the 

fairing system failed to separate. The detailed analysis pointed to a failure to fracture 

near the forward end of one of the fairing side rails, which prevented full separation. The 

extra pressure sensor added to the installation of the cold gas pressurization system, in 

place of the hot gas generator system as part of the response to the T8 MIB report, 

provided valuable data to the T9 MIB. This sensor data verified the cold gas 

pressurization system performance was satisfactory and that the T9 payload fairing’s 

base ring indeed had separated. As a result, the T9 MIB could eliminate the cold gas 

pressurization system and the base ring as a cause and focus on the scenario in which 

the forward end of the payload fairing side rail failed to fracture. 

Intermediate Causes 

The T9 MIB examined all potential intermediate causes closely and concluded that the 

most likely intermediate causes were the two items listed below from the Event and 

Causal Factors Tree that were categorized as “possible:” 

 

 Side rail charge holder slumped or compressed 

Design analysis and ground testing of frangible joint components during the 

course of the investigation led the T9 MIB to conclude that the rubber charge 

holder, an internal component of the frangible joint, could have slumped due to 

the effects of launch acceleration and random vibration, resulting in incomplete 

fracture of the fairing side rails. 

 Side rail system failed to operate correctly outside its evaluated 

environments 

The second possible intermediate cause was an expansion of the first. Because 

the charge holder slumping scenario was identified early in the investigation 

process, considerable focus was placed on that component. It became clear to 

the T9 MIB that the lack of testing and analysis throughout the life cycle of the 

frangible joint applied not only to the charge holder, but to the other components 

comprising the frangible joint system. Consequently, while the first possible 

intermediate cause considers the charge holder alone, the second possible 

intermediate cause considers the rest of the joint system and the interaction 

between system components. There may be additional undiscovered failure 

modes due to untested environments within the joint system. Analysis and 

testing must be applied to the frangible joint system and not solely to the charge 

holder. 

 
7

Root Cause Analysis

While the T9 MIB was able to identify the proximate cause and two possible 

intermediate causes for the T9 mishap, they were unable to identify the root cause for 

this failure. As a matter of explanation, an intermediate cause is between the proximate 

cause and the root cause in the causal chain. The root cause is the factor or set of 

factors that contributes to, or creates the proximate cause. Typically multiple root 

causes contribute to an undesired outcome. 

The T9 MIB was unable to determine a root cause for the mishap mainly due to limited 

flight telemetry and the inability to recover the payload fairing hardware for analysis that 

would have enabled the determination of a definitive intermediate cause or causes. 

While the T9 MIB was unable to identify a root cause, they made several technical 

observations and findings which are summarized below: 

 The T9 MIB determined that side rail charge holder slumping (compression) 

could possibly occur because of the following: 

1. The Side Rail assembly’s susceptibility to (and the effects of) charge 

holder slump was not previously identified. 

 

2. The temporal distribution of acceleration, vibration, shock environments 

had changed over time. 

3. Orbital’s fairing joint buildup process variability could affect charge 

holder slumping susceptibility. 

 In addition, the T9 MIB noted a large percentage of potential causes rated as 

“possible, but highly unlikely” involved frangible joint components and also 

observed that Orbital's manufacturing processes were not as tightly controlled as 

those applied by NASA in other pyrotechnic hardware designs. The possibility 

exists that manufacturing process controls could allow variation in material 

properties and hardware dimensions that may impact system performance. 

 The T9 MIB did not find evidence that a detailed failure analysis of the frangible 

joint design used on the Taurus was performed at any point in its life cycle. 

Details of the design had evolved since the genesis of the base ring application 

for the Pegasus launch vehicle, and the effects of those evolutionary design 

changes, including the potential for charge holder slump, were not discovered. 

 The T9 MIB also discovered that the qualification activity for the frangible joint 

system was generally performed at the subscale level, using industry practices 

for the qualification of pyrotechnic devices. The effects of all flight environments, 

either individual or combined, were not always considered. As with the system 

design, the flight environments also have evolved over time, and the effects of 
8

these changes on system performance margins should be understood. 

As a result of the analyses performed, the T9 MIB made the following technical 

recommendations: 

1. Orbital should establish frangible joint system manufacturing process 

controls sufficient to assure that variability in materials properties and 

hardware component dimensions, within both maximum and minimum 

tolerances, will not invalidate design performance requirements. 

2. An extensive failure analysis (for example, detailed fault tree or failure 

mode analysis) of the Taurus frangible joint design should be performed. 

3. Design and implement a qualification and test activity for the Taurus 

frangible joint system based on the results of an extensive failure analysis 

(for example, detailed fault tree or failure mode analysis) and with 

consideration for the environments in which the joint is operated.

“The MIB believes that if this recommendation were implemented, it 

could address all the possible frangible failure scenarios identified 

in the investigation.” 

During the course of the mishap investigation, additional observations and 

recommendations related to Agency policy, special assessment procedures, and 

improved communications were noted by the T9 MIB. Although these items were not 

deemed causal to the launch failure by the T9 MIB, the MIB determined that they could 

be beneficial for future programs.