Public Release Summary of the 

Geostationary Operational 

Environmental Satellite-17 (GOES-17) 

Advanced Baseline Imager (ABI) 

Loop Heat Pipe (LHP)

Mishap Investigation Board Report

Mishap Declared: 28 September 2018

This document was reviewed and approved for public release on 

30 July 2019. 
Overview of the Geostationary Operational Environmental Satellite-17 (GOES-17) Advanced 

Baseline Imager (ABI) Loop Heat Pipe (LHP)

Mishap Investigation Board Report

For Public Release

Mishap Summary 

The National Oceanic and Atmospheric Administration (NOAA) operates a system of 

environmental satellites in geostationary orbits to provide continuous weather imagery and 

monitoring of meteorological data for the United States, Latin America, much of Canada, and most 

of the Atlantic and Pacific Ocean basins. The Geostationary Operational Environmental Satellite 

(GOES) system provides atmospheric, oceanic, climatic, and solar products supporting weather 

forecasting and warnings, climatologic analysis and prediction, ecosystems management, and safe 

and efficient public and private transportation. The GOES system also provides a platform for 

space environmental observations, and auxiliary communications services that provide for GOES 

data rebroadcast, data collection platform relay, low-resolution imagery, emergency weather 

communications, and satellite-aided search and rescue.

The GOES-R Series Program is a collaborative effort between NOAA and the National 

Aeronautics and Space Administration (NASA) to extend the availability of the operational GOES 

system through 2036. The GOES-R Series includes development and acquisition of spacecraft, 

instruments, launch services, and all associated ground system elements and operations for four 

satellites. These satellites are designated GOES-R/S/T/U until they reach orbit, at which time they 

are renamed GOES-16/17/18/19. GOES-16 (formerly called GOES-R) serves as the operational 

geostationary weather satellite over the U.S. east coast. GOES-17 (formerly called GOES-S)

became the operational GOES West satellite on February 12, 2019. The remaining GOES-R Series 

satellites, GOES-T and GOES-U, are currently in development.

The Geostationary Operational Environmental Satellite-S (GOES-S) spacecraft was launched on 

March 1, 2018, and achieved geostationary orbit on March 12, 2018. GOES-S was officially redesignated GOES-17 upon reaching geostationary orbit. The spacecraft was powered on and the 

outgassing phase began on March 19, 2018. The GOES-17 Advanced Baseline Imager’s (ABI’s)

Optical Port Cover (OPC) was opened April 13, 2018. The ABI is the primary instrument on the 

GOES-R Series of satellites for imaging Earth’s weather, oceans and environment. ABI views the 

Earth with 16 different spectral bands (compared to five on the previous generation of GOES), 

including two visible channels, four near-infrared (IR) channels, and ten IR channels. These 
different channels (wavelengths) are used by models and tools to indicate various elements on the 

Earth’s surface or in the atmosphere, such as trees, water, clouds, moisture or smoke. ABI is a 

mission-critical payload for the GOES-R Series, providing more than 65 percent of all mission 

data products currently defined. 

Following the opening of the ABI’s OPC, the two loop heat pipes (LHPs) in the ABI’s 

radiator/loop heat pipe (R/LHP) cooling system began to self-start every day when entering the 

hot phase of the orbit (approximately 6:30 Coordinated Universal Time [UTC]), where light from 

the Sun entered the optical port. The LHPs (designated LHP1 and LHP2) would run for 

approximately three hours and would then shut down after the Sun’s light no longer entered the 

optical port. These self-starts were not planned; however, self-starts were considered normal in 

LHP operations. 

At 22:19 (UTC) on April 28, 2018, flight controllers commanded the LHP start-up heaters to 

activate for the first controlled start of the GOES-17 ABI LHPs. Both LHPs started at 

approximately 22:52; however, telemetered temperatures indicated the LHPs were 

underperforming. The evaporator temperatures (an indicator of how well LHPs carry heat load) 

fell from 292K to only about 286K (versus an expected ~270K) over 15 minutes before beginning 

to rise. This situation was indicative of the LHP’s entering a “laggard” mode in which heat could 

not be effectively transferred to the radiator. LHP2 shut down at 0:05 (UTC) April 29, 2019. The 

flight controller commanded a shutdown of both LHPs at 2:03 (UTC).

The following day, April 29, 2018 flight controllers attempted to test the two loop heat pipes 

independently. During these tests LHP2 did not initialize but LHP1 did. However, it was noted 

that LHP1 was not able to carry the full thermal load from the cryocoolers without exceeding 

preset limits on temperature. Data logs show both LHPs self-starting around 6:45 (UTC), and 

running until ~9:40. Flight controllers began to attempt to re-start LHP2 at 22:20 on April 29, 

2018. Telemetered data indicated a start-up of LHP2 at 23:05. However, LHP2 was transferring 

relatively little heat. At ~23:45, flight controllers shut down the cryocoolers and LHP2. A similar 

attempt was made with LHP1 starting an hour later (0:40, April 30, 2018 UTC). Although LHP1 

was carrying more heat load than LHP2, the heat load was still short of the expected amount. LHP1 

was allowed to continue running until 14:53 (UTC) on May 1. 

The GOES-R Flight Project continued troubleshooting the LHP issue for the next several months. 

On May 16, 2018 a yaw flip was executed in an attempt to test LHP performance with no direct 

solar loading from the radiator; however, this maneuver did not improve LHP performance. On 

May 23, 2018 NOAA publicly announced that there was an anomaly, and on May 29 a GOES-R 

Program-convened Independent Review Team (IRT) had its first meeting at the Advanced 

Baseline Imager (ABI) Contractor facilities in Fort Wayne, Indiana. The IRT was staffed by LHP 

experts from within and external to NASA and was focused on the physical hardware in developing 

a set of most likely proximate causes. An Optimization Team (consisting of members from the 

GOES-R Project team, the ABI Contractor, Spacecraft Contractor, and the user community) was 
also established to develop procedures to obtain as much data as possible out of the satellite. This 

team held its first meeting in Fort Wayne, Indiana the following week. The Optimization Team 

has been able to define alternate operations, procedures and hardware operating limits which have 

resulted in a 97 percent data availability for the GOES-17 ABI. With 97 percent data availability 

restored, GOES-17 became the operational GOES West satellite on February 12, 2019. 

The lack of adequate cooling results in periodic loss of IR data on 13 of the 16 ABI spectral 

channels. The instrument’s infrared detectors cannot be maintained at their required operating 

temperatures under certain seasonal and orbital conditions, resulting in a loss of approximately 

three percent of the instrument’s availability over the course of a year1. A key performance 

parameter is that the ABI cannot experience data outages of more than six hours per year. Although 

the Optimization Team has provided 97 percent data availability, the inability to meet the limit of 

six hours or less of data outage per year resulted in NASA and NOAA declaring a mishap and 

jointly convening the GOES-17 ABI LHP Anomaly Mishap Investigation Board (MIB) on 

September 28, 2018. For the purpose of classifying the mishap, the estimated direct cost of the 

mishap was calculated as 3% of the $100M cost of the GOES-S ABI instrument. The $3M direct 

cost resulted in the mishap being entered as a Type-A mishap into the NASA Mishap Information 

System (NMIS).

GOES-17 MIB Investigation Process and Results

The MIB was tasked with gathering information; analyzing the facts; identifying the proximate 

causes, root causes, and contributing factors related to the ABI LHP performance issues; and 

recommending actions to prevent a similar mishap from occurring. The MIB conducted its 

investigation according to NPR 8621.1C, NASA Procedural Requirements for Mishap and Close 

Call Reporting, Investigating, and Recordkeeping2The MIB gathered evidence from over 30 one 

on one interviews and discussions, visits to the ABI Contractor and LHP Subcontractor sites, a 

large amount of project documentation, telemetered flight data, and pre-launch and post-anomaly 

test data and used this information to generate timelines, a Fault Tree and an Event and Casual 

Factor Tree (ECFT). The MIB based its Fault Tree and the resulting event and causal analysis on 

an undesired outcome related to the loss of mission data resulting from the inadequate cooling of 

the ABI detectors. Although the loss of data to support the NOAA mission is a critical aspect of 

the undesired outcome, the MIB also included, for consistency, a reference to the direct cost used 

to classify the mishap in the following undesired outcome: The GOES-17 ABI Experienced a $3M 

Loss of Mission Data due to Inadequate Cooling of the ABI Detectors.

The MIB developed a fault tree with the undesired outcome as the top-level failure event and 

populated the tree by incorporating additional elements that could potentially lead to the undesired 

outcome. Upon completion of the fault tree, the MIB evaluated each element to determine whether 

it could be closed (i.e., to prove it could not have occurred) so that it could be “ruled out” as a 
causal factor. The MIB had at its disposal a significant amount of data and analysis provided by 

the IRT, the ABI Contractor and LHP Subcontractor that examined the potential physical or 

“hardware” causes of the anomaly. The MIB thoroughly analyzed and carefully considered this 

data as it assessed the independently developed Fault Tree elements to support the causal analysis. 

NASA has completed the Agency’s assessment of the GOES-17 MIB report. The report is NASA

sensitive, but unclassified (SBU), because it contains company proprietary information. The report 

also contains information restricted by the International Traffic in Arms Regulations (ITAR)

and/or the Export Administration Regulations (EAR). This summary report provides an overview 

of publicly releasable information contained in the full report.

Proximate Cause and Highest-Level Intermediate Cause

Through its causal analysis, the MIB identified the following proximate cause and highest-level

intermediate cause:

GOES-17 MIB-determined Proximate Cause: 

ECFT-3: The ABI R/LHP System Failed to Reject the Necessary Heat to Cool the ABI Detectors as 

Designed

The R/LHP may not have been able to dissipate all of the heat routed to it due to a design or 

operational limitation or an on-orbit condition. This event assumes that the amount of heat routed 

to the LHP was within the design limit. Analysis of the LHP performance on orbit shows that 

LHPs initially were only carrying 60 W of heat load, and that load soon after dropped to 10 W to 

20 W. The on-orbit requirement is 390 W. This indicates that there was either a design issue or failure 

on-orbit.

GOES-17 MIB-determined highest-level Intermediate Cause: 

ECFT-6: The ABI LHPs had Insufficient Working-Fluid Flow to Carry the Required Heat Load

This intermediate cause indicates that the movement of the working fluid was inadequate to 

dissipate the heat load being provided to the LHP.

With the limited set of available telemetry data and without the ability to evaluate the in-flight 

hardware, the R/LHP failure could not conclusively be isolated to a specific part or failure. These 

circumstances prevented the MIB from developing causal linkages below the intermediate level. 

However, after reviewing all of the data available, the MIB concludes that the most likely technical 

explanation for the failure of the GOES-17 LHPs to transport and reject their expected heat load 

is physical blockage of the LHP assembly by particulates contained in the working fluid.

In its causal analysis, the MIB examined objective evidence for causal elements in six categories 

(quality, requirements, design, testing, contamination, and structures) to assess the impact of each 

element as a potential contributor to the mishap. The MIB determined the engineering, process, 
and organizational issues related to those elements and have provided recommendations to address 

the issues identified.

Overview of GOES-17 MIB Recommendations: 

An overview of the intent of key recommendations from the MIB report is provided below. 

NASA/NOAA will determine how these recommendations apply to the GOES-R program as well 

more generally to other programs in both agencies. 

• When presented with evidence that requirements are driving significant design changes or 

unique design solutions, a requirements vs. design trade should be performed to assess the 

rationale for the higher level requirements and decomposition of these requirements to reduce 

design risk. This assessment should be conducted as part of the convening authorities’

evaluation during milestone design reviews. 

• Contractors’ deliverables should be evaluated to ensure that failure modes and effects analyses 

(FMEAs) include failure modes, criticality, and mitigation plans down to the component level 

for all instrument subsystems including subcontractor hardware. 

• The use of Technology Readiness Assessments on ALL new flight builds should be used 

during formulation to ensure an adequate risk posture is identified (as discussed in the Final 

Report of the NASA Technology Readiness Assessment [TRA] Study Team [2016]3, located 

at: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170005794.pdf

• Data delivery requirements should be levied on prime contractors to enable the required TRA 

to be performed by NASA on the contractors’ designs. An evaluation of the technology 

readiness level (TRL) of new technologies should be required at the preliminary design review 

(PDR). 

• The roles and responsibilities of program and project leadership down to the instrument level

should be included in program/project documentation to clarify decision-making authority, 

ownership, and accountability. These roles and responsibilities should be reviewed with the 

team, Program Management and institutional engineering to facilitate understanding and 

ensure personnel with the required skills are assigned.

• NASA/NOAA project team members should be encouraged to ask questions and initiate 

requests for action (RFAs) during the Lifecycle Design Reviews.

• Any actions and issues identified during a Lifecycle Review dry run that are still open at the 

time of the lifecycle review should be required to be submitted as RFAs for evaluation by the 

board. 
• Requirements that are derived for fluid system cleanliness should be compatible with the 

smallest expected flow path dimensions and the system sensitivity to particulates. 

• Cleaning procedures should be in place (including procedures for subsystems and components) 

to verify through testing that the final particulate levels of working fluids in closed systems 

meet the contamination requirements of the system designs. 

• A process for how NASA participates and establishes a technical position at contractor Failure 

Review Boards (FRBs) should be documented.

• Training to re-inform personnel supporting projects about pathways to voice concerns and the 

roles and responsibilities of technical authorities (TAs) should be provided. This training 

should re-emphasize the importance of expressing alternate viewpoints and dissenting 

opinions.

• All TA representatives should be directed to actively seek out issues and alternate viewpoints 

from discipline engineering leads, subject matter experts (SMEs), and safety and mission 

assurance (S&MA) personnel (quality assurance providers, mission assurance personnel, 

safety experts, etc.) at all levels within projects. To encourage these discussions, the program 

should develop a process or institute a forum to document and discuss alternate viewpoints to 

ensure they are appropriately heard, considered and addressed. 

• All performance data from systems of the same design (i.e., the same series of instruments, 

including other systems tested for other customers) should be required to be evaluated as part 

of the FRB process and that all possible differences in hardware (e.g. different lots or 

manufacturers) are assessed thoroughly as contributing factors internal and external to the 

system.

• The documented NASA FRB position should be reviewed for increased risk level or new risks, 

especially when no definitive root cause for an issue is identified; document a formal 

conclusion on whether there is a new or increased risk level; and elevate areas of increased risk 

to the Program Risk Board. 

• Independent problem resolution teams including technical experts outside the project (reaching 

across the Agency) should be used when an FRB finds no definitive root cause and project risk 

is increased. The use of an independent problem resolution team should be discussed and 

evaluated as part of developing a NASA/NOAA technical position.

• The components of a flight system that are capable of shedding particles that might affect the 

system performance should be identified and design requirements should be developed to 

enable the system to perform as intended.
• When proprietary data concerns result in a contractor presenting high-level summary 

statements and general conclusions without supporting detailed data, NASA should question 

and scrutinize such summary statements and conclusions.

• NASA should identify and implement flight instrumentation to more easily enable forensics or 

diagnostic capabilities.

1

GOES-R Series website: https://www.goes-r.gov/users/GOES-17-ABI-Performance.html

2

NPR 8621.1C, NASA Procedural Requirements for Mishap and Close Call Reporting, Investigating, and 

Recordkeeping

3

HQ-E-DAA-TN43005, Final Report of the NASA Technology Readiness Assessment (TRA) Study Team (March 

2016).