April 2009 

NASA/TM-2009-215710 

NESC-RP-05-88/04-034-E 

 

International Space Station/Shuttle “Flip” 

Maneuver for Thermal Protection System 

Repair Consultation Report 

Cornelius J. Dennehy/NESC 

Goddard Space Flight Center, Greenbelt, Maryland 

Frank Bauer 

Ames Research Center, Moffett Field, California 

Karl D. Bilimoria 

NASA Headquarters, Washington, DC 

Dennis B. Dillman/NESC 

NASA Headquarters, Washington, DC 

Michael G. Gilbert/NESC 

Langley Research Center, Hampton, Virginia 

Michael Hagopian/NESC 

Goddard Space Flight Center, Greenbelt, Maryland 

Tuyen Hua 

Johnson Space Center, Houston, Texas 

Jay Leggett/NESC 

Johnson Space Center, Houston, Texas 

Peiman G. Maghami, David J. Mangus, and Scott R. Starin 

Goddard Space Flight Center, Greenbelt, Maryland 
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April 2009 

NASA/TM-2009-215710 

NESC-RP-05-88/04-034-E 

 

International Space Station/Shuttle “Flip” 

Maneuver for Thermal Protection System 

Repair Consultation Report 

Cornelius J. Dennehy/NESC 

Goddard Space Flight Center, Greenbelt, Maryland 

Frank Bauer 

Ames Research Center, Moffett Field, California 

Karl D. Bilimoria 

NASA Headquarters, Washington, DC 

Dennis B. Dillman/NESC 

NASA Headquarters, Washington, DC 

Michael G. Gilbert/NESC 

Langley Research Center, Hampton, Virginia 

Michael Hagopian/NESC 

Goddard Space Flight Center, Greenbelt, Maryland 

Tuyen Hua 

Johnson Space Center, Houston, Texas 

Jay Leggett/NESC 

Johnson Space Center, Houston, Texas 

Peiman G. Maghami, David J. Mangus, and Scott R. Starin 

Goddard Space Flight Center, Greenbelt, Maryland 
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International Space Station/Shuttle “Flip” Maneuver for 

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Consultation Report 

July 21, 2005 
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TABLE OF CONTENTS 

VOLUME I: CONSULTATION REPORT 

1.0 AUTHORIZATION AND NOTIFICATION......................................................4 

2.0 SIGNATURE PAGE..............................................................................................5 

3.0 TEAM MEMBERS................................................................................................6 

4.0 EXECUTIVE SUMMARY ...................................................................................7 

5.0 CONSULTATION PLAN ...................................................................................18 

6.0 DESCRIPTION OF PROBLEM, PROPOSED SOLUTIONS, RISK 

 ASSESSMENT .....................................................................................................20 

7.0 DATA ANALYSIS...............................................................................................23 

8.0 FINDINGS, ROOT CAUSES, OBSERVATIONS, and 

RECOMMENDATIONS.....................................................................................24 

8.1 Findings..................................................................................................................24 

8.2 Recommendations..................................................................................................29 

9.0 LESSONS LEARNED.........................................................................................34 

10.0 DEFINITION OF TERMS..................................................................................35 

11.0 LIST OF ACRONYMS .......................................................................................36 

12.0 MINORITY REPORT.........................................................................................38 

List of Figures

4.0-1 Orbiter Repair Access Diagram...............................................................................7 

4.0-2 Orbiter at the ORM Overnight Park Position ........................................................11 

4.0-3 Orbiter at the ORM Repair Position (with respect to ISS) ....................................12 

3.0-4 Orbiter at the ORM Repair Position (Side View)..................................................13 
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List of Tables

8.1-1 List of ORM Open Work (as of 10 June 2005) .......................................................28 

VOLUME II: APPENDICES

Appendix A. NESC ITA/I Request form (NESC-003-FM-01).......................................39 

Appendix B. NESC ORM Peer Review Agenda (8-10 June 2005) ................................43 

Appendix C. ORM STS-114 FRR Chart package (dated 27 June 2005)........................46 

Appendix D. April 2005 ORM Status Report .................................................................49 
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NESC Request No. 04-034-E 

Volume 1: Technical Consultation Report 

1.0 Authorization and Notification 

Michael Gilbert, the NESC Chief Engineer at LaRC, was the initiator of this activity. 

David Hamilton, the NESC Chief Engineer at JSC, performed the initial evaluation of 

this item. Per the official minutes, the NESC Review Board (NRB) approved this activity 

as a technical consultation on 27 April 2004. The key stakeholders for this consultation 

report are the Space Shuttle Program (SSP) and the International Space Station (ISS) 

Program.
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2.0 Signature Page 

NESC Team Members 

______________________________ ______________________________ 

Cornelius Dennehy Frank Bauer 

______________________________ ______________________________ 

Karl Bilimoria Dennis Dillman 

______________________________ ______________________________ 

Michael Gilbert Michael Hagopian 

______________________________ ______________________________ 

Tuyen Hua Dexter Johnson 

______________________________ ______________________________ 

Jay Leggett Peiman Maghami 

______________________________ ______________________________ 

David Mangus Scott Starin
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3.0 Team Members

Several members of the NESC Guidance, Navigation and Control (GN&C) Super 

Problem Resolution team (SPRT) have been providing high-level oversight of the 

technical and programmatic activities surrounding the ORM since July 2004. This small 

group of GN&C specialists was augmented with additional NESC personnel to form a 

diverse ORM Peer Review Team capable of performing both an overall system-level 

assessment of the ORM and a detailed technical interrogation in key identified areas of 

interest. The following individuals comprised the June 2005 NESC ORM Peer Review 

Team: 

Name Title Affiliation Phone E-Mail 

Neil Dennehy GN&C Discipline 

Engineer 

NESC, LaRC 301/286-5696 Cornelius.J.Dennehy@nasa.gov 

Frank Bauer GN&C SPRT NESC, ARC 202/358-0897 Frank.H.Bauer @nasa.gov 

Karl Bilimoria GN&C SPRT NESC, HQ 650-604-1638 Karl.Bilimoria@nasa.gov 

Dennis Dillman Chief Engineer NESC, HQ 202/358-1759 Dennis.B.Dillman@nasa.gov 

Michael Gilbert Chief Engineer NESC, LaRC 757/864-2839 michael.g.gilbert@nasa.gov 

Michael Hagopian GSFC Chief 

Engineer 

NESC, LaRC 301/286-6732 Michael.hagopian@nasa.gov 

Tuyen Hua GN&C SPRT NESC, JSC 281/483-8296 Tuyen.Hua-1@nasa.gov 

Dexter Johnson GN&C SPRT NESC, GRC 216/433-6046 Dexter.Johnson@nasa.gov 

Jay Leggett NESC Systems 

Engineering Office 

NESC, JSC 281/483-6458 Jay.A.Leggett@nasa.gov 

Peiman Maghami GN&C SPRT NESC, GSFC 301/286-6615 Peiman.Maghami@nasa.gov 

David Mangus GN&C SPRT NESC, GSFC 301/286-2649 David.J.Mangus@nasa.gov 

Scott Starin GN&C SPRT NESC, GSFC 301/286-9627 Scott.Starin@nasa.gov 
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4.0 Executive Summary 

The intent of this Technical Consultation Report is to document the finding and 

recommendations of the NESC Orbiter Repair Maneuver (ORM) Peer Review conducted 

at NASA’s Johnson Space Center (JSC) with the ORM Working Group (WG) over the 

period 8-10 June 2005. 

Background

The ORM is a complex, untested, and hazardous human/robotic contingency operation 

spread over three (3) days. It has been developed by JSC to support the repair of entry 

critical Thermal Protection System (TPS) tile and Reinforced Carbon-Carbon (RCC) 

damage at locations that cannot be reached, with the Orbiter docked to ISS, by either the 

Shuttle Remote Manipulator System (SRMS) or the Space Station Remote Manipulator 

System (SSRMS). As depicted in Figure 4.0-1 the ORM has been designed and 

developed to position the Orbiter such that 100 percent of the TPS tile is within reach of 

an EVA astronaut on the SSRMS. The ORM entails undocking the Orbiter from the ISS 

using the SRMS, followed directly by the SRMS maneuvering of the Orbiter through a 

series pre-planned (and auto-sequenced) trajectory waypoints, in close proximity to the 

ISS, to a repair orientation accessible by Extravehicular Activity (EVA) astronauts 

positioned on the SSRMS. 

Repair Access (Pre Node 2)

(Docked & ORM: Lab and MBS Worksites 4 & 5)

Panel 15

No access

Access with SRMS when docked

ORM Access

Docked Access or ORM 

Docked Access Only

No Access

Panel 11

Figure 4.0-1. Orbiter Repair Access Diagram 
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The Space Shuttle Project (SSP) considers the ORM to be a contingency operation for 

flights LF1-10A. There is no plan for the Project to certify the ORM. The initial ORM 

plan called for all analyses to be complete and the operational procedures to be ready for 

STS-114. That initial plan has been overcome by events. While much progress has been 

made over the last several months in many of the analytical areas, especially the 

characterization of the repair worksite dynamics, the complete technical solution for the 

ORM is still being developed at JSC on a “best efforts” basis by multiple engineering and 

operational organizations. 

The NESC team’s position is that, compared to the Orbiter/ISS/SRMS/SSRMS 

experience base, the ORM has a high-degree of complexity, uncertainty and therefore 

risk to crew and the flight structures. It involves close proximity movements of the 

Orbiter, ISS, the SRMS, the SSRMS structures and requires split-crew astronaut 

operations inside the Orbiter and ISS as well as EVA astronauts on the SSRMS to 

perform the repairs. 

Peer Review Approach and Objectives 

The motivation for the Peer Review was derived from NESC’s concern that ORM 

represents new and unfamiliar operations that are complex and pose risks (both know and 

unknown) to the crew and flight systems. The team’s approach to performing this most 

recent ORM peer review was twofold. The team first reviewed the ORM from a “big 

picture” systems-level viewpoint to determine, to the extent a short duration review such 

as this would permit, if the ORM WG missed any key aspects of the problem. The team 

then investigated a few key technical areas to evaluate the depth and completeness of 

some of the ORM WG’s analysis, modeling and simulation work. 

Specific objectives of the NESC ORM Peer Review were: 

1) To assess the breadth of the ORM technical solution at a systems–level. 

 

2) To assess the status, depth, and completeness of the ORM pre-launch modeling, 

simulation and analysis work performed to date. 

3) To determine what ORM work remains to be completed. 

4) To assess the ORM operational readiness for STS-114. 

5) To understand the risks associated with performing the ORM and determine if 

there are any “showstoppers.” 
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6) To determine if the ORM WG was proceeding down the path towards a 

successful ORM. 

ORM Operations 

The ORM is a complex contingency operation that cannot be fully validated on the 

ground prior to first use. Moreover the ORM is a “first of a kind” operation whose 

execution will require both the flight hardware and the crew to operate in a non-standard 

manner that is significantly outside the nominal operational experience regime. If 

invoked the ORM would be the first SRMS “Heavy Payload” operation and would also 

be the first use of the SRMS for undocking the Orbiter from the ISS. The heaviest SRMS 

payload to date has been the Functional Energy Block (known as FGB), which had a 

mass of approximately 48,000 pounds. Note also that SRMS-assisted docking operations 

have not been done since STS-88/2A, which was the first ISS assembly mission, in 1998. 

It is important to recognize that “ORM” is a broad term that covers the end-to-end 

operation of first undocking the Orbiter, SRMS maneuvering of the Orbiter via multiple 

prescribed trajectory waypoints to the repair position, the subsequent Orbiter/EVA 

astronaut dynamic (relative motion) interactions at the repair worksite and the 

maneuvering and redocking of the Orbiter following completion of the repairs. 

During the ORM, as mentioned above, the Orbiter is maneuvered by the SRMS through 

multiple pre-determined trajectory waypoints in an auto-sequenced manner. There are in 

fact a total of thirteen (13) maneuver waypoints during this operation. Early on in the 

ORM dynamics and controls analysis process the JSC GN&C team concluded that the 

existing as-is ISS CMG-based attitude control system did not have sufficient 

capability/authority to stabilize the various stack configurations during the SRMS 

maneuvering of the Orbiter through the multiple waypoints. During the ORM the ISS 

GN&C system alone is used to control the attitude of the entire ISS/Orbiter stack. The 

Orbiter GN&C system is in a passive state (with its control actuators not enabled) and it 

is not used to control the dynamics of the stack. In order to provide adequate attitude 

control of the ORM stack configurations from Waypoints 1-13, a new ORM-specific 

controller and operational mode was designed by the JSC GN&C team to provide stable 

operational performance. This new GN&C operational mode, referred to as the United 

States (US) Thruster-Only (USTO) mode, uses the existing US CMG ProportionalDerivative (PD) control law algorithm to only command Russian Segment (RS) Service 

Module (SM) thrusters in a Pulse Width Modulation (PWM) mode. The JSC GN&C team 

selected thrusters (instead of the CMG’s) as the ORM control actuators in order to 

provide good attitude control performance while achieving acceptable Orbiter relative 
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motion with respect to the ISS. The CMG’s are not used at all, during ORM maneuvering 

of the Orbiter, to generate attitude control torques. 

The ORM is a relatively long duration (3 days) multi-step process that begins with the 

Orbiter docked to the ISS and, from a dynamics and control perspective, includes the 

following specific events: 

1) Grappling of ISS by the SRMS (with ISS under normal CMG MM control). 

2) SRMS controlled undocking of the Orbiter from ISS and subsequent maneuvering to 

 Waypoint 1 (with ISS under normal CMG MM control).* 

3) Transition of ISS GN&C from normal Control Moment Gyro (CMG)-based MM 

 control mode to the US Thrusters Only (USTO) thruster-based attitude hold control 

 mode. The CMG’s are placed in a free drift mode.* 

4) Maneuvering of the Orbiter, via auto-sequenced SRMS motion, from Waypoint 1 to 

 the Overnight Park Position (Waypoint 8) with the ISS under USTO thruster-based 

 attitude hold control.* 

5) Transition of ISS GN&C from USTO thruster-based attitude hold control back to 

 normal CMG-based MM control at the Overnight Park Position. * 

6) Maintaining the Orbiter/ISS stack in a Torque Equilibrium Attitude (TEA) at the 

Overnight Park Position (Waypoint 8) under normal CMG MM control.* 

7) Transition of ISS GN&C from normal CMG-based MM control to USTO thruster 

 based attitude hold control. The CMG’s are placed in a free drift mode. 

8) Maneuvering of the Orbiter, via auto-sequenced SRMS motion, from the Overnight 

 Park Position (Waypoint 8) to the Repair Position (Waypoint 13) with the ISS under 

 USTO thruster-based attitude hold control.* 

9) Transition of ISS GN&C from USTO thruster-based attitude hold control back to 

 normal CMG-based MM control at the Repair Position. * 
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10) Providing a sufficiently stable repair worksite dynamic environment, with the ISS 

 under CMG-based MM control, to permit the required TPS tile or RCC repair by 

 EVA astronauts positioned on the SSRMS affixed to ISS.* 

11) Post-repair maneuvering and re-docking of the Orbiter, by performing Step 9 through 

 Step 1 in reverse order.* 

 

• Note: The * indicates a first time operational occurrence. 

Figure 4.0-2 depicts the Orbiter at the ORM overnight park position while Figures 4.0-3 

and 4.0-4 illustrate the Orbiter at the ORM repair position. 

Overnight Park Position

Figure 4.0-2. Orbiter at the ORM Overnight Park Position 
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Repair Position

Figure 4.0-3. Orbiter at the ORM Repair Position (with respect to ISS)
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ORM Repair Position

Figure 4.0-4. Orbiter at the ORM Repair Position (Side View) 

Summary of Key Findings and Recommendations 

The NESC team had ten (10) findings and five (5) recommendations coming from the 

limited (2.5 day) “snapshot” pre-RTF review of the ORM status. Some of these findings 

and recommendations address known technical concerns with specific aspects of the 

GN&C system design and performance. Others relate to system level concerns with the 

quantity of known open work, the need to integrate and prioritize activities across 

organizations, and the strategic implementation of on-orbit checks into the operational 

plan to account for remaining ORM uncertainties. 

The team found that that while the ORM WG structure was a useful way to share 

information between multiple organizations there apparently is no single person tasked 

with coordinating/managing the overall effort, from an end-to-end system perspective, on 

a full-time dedicated basis. It is the team’s position that the lack of a dedicated full-time 

ORM Lead Engineer has impacted, and continues to impact, the integration and 
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prioritization of open ORM analytical and operational planning work. A full-time ORM 

Lead Engineer, with a system-wide perspective, is critically needed to both prioritize and 

schedule completion dates for all remaining ORM open work based upon negotiated 

agreements with appropriate resource managers. This ORM engineering lead could be 

positioned to efficiently identify and complete remaining work in preparation for launch, 

to authoritatively communicate ORM status and capability to the SSP, and to support real 

time on-orbit analysis and decision-making should the ORM be invoked. 

One of the team’s primary technical concerns focuses on low reported stability margins 

for the ISS USTO attitude control system. In particular, the team was very concerned 

with low reported phase margins - as low as 4.5 degrees in one specific case. 

Specifically “phase margin” is defined as the amount of additional phase lag (at the gain 

crossover frequency) that is required to bring the system to the verge of instability 

Therefore, these low phase margins indicate that, under certain operating conditions, the 

ISS attitude control system could be operating very near the boundary of stability. 

 

In classical linear control system theory gain and phase margins are typically used as 

figure-of-merit measures indicating the degree of stability in a closed-loop feedback 

system. Control system designers gain important insights into a control system’s 

robustness to uncertainty by computing and evaluating the gain and phase margins. 

Uncertainty can manifest itself in a control system in several ways such as un-modeled 

plant dynamics (that perhaps could be excited by the control system), and/or nonlinearities that were not included in the plant model (or perhaps not known to exist) 

and/or unknown/unanticipated variations in plant parameter values. Standard engineering 

best practice guidelines suggest that a control system possess both a minimum of 30 

degrees of phase margin, and a minimum of 6 dB of gain margin to adequately provide 

robustness to uncertainty. 

 The team’s position is that the low reported phase margins are not acceptable given that: 

a) the ORM is a first-of-a-kind maneuver, 

b) there is limited experience with a USTO type controller that combines the US 

CMG control law algorithm with the RS SM thrusters, 

c) the on/off control of the thrusters is implemented via the PWM such that the exact 

time for the execution of a thruster firing is variable and depends on the command 

levels, and 
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d) effects of sensor dynamics, as well as some discretization effects, do not seem to 

have been included in the GN&C ORM analyses. The belief/posture that these 

low phase margins, which are based on a linear model of the SRMS, are overly 

conservative is not a sufficient basis to proceed with the current USTO controller 

design. 

It is the position of the team that the critical importance of maintaining controller stability 

is paramount in the case of the ORM where the Orbiter-to-ISS maneuver clearances are 

tight. Controller instability could directly lead to collision and damage/loss of the 

Orbiter/ISS stack. 

It is also the position of the team that potentially low controller margins coupled with 

remaining (both known and unknown) uncertainties dictate that deliberate ORM steps 

with engineering checks be embedded into the operations plans/procedures to evaluate 

ORM performance and gain confidence prior to these key activities. This philosophy 

should be extended to address other areas of uncertainty like the dynamic worksite 

environment. Astronauts can excite the complex control-structure system stack from a 

safe position near the repair site, by dry running the nominal repair steps, to gain 

confidence prior to the actual repair. It may be possible that previous work, including 

early planning for the ORM Demonstration Task Objective (DTO), can be leveraged to 

determine what is feasible and appropriate. 

Summary Remarks 

Based upon cursory review, the team recognizes that the majority of the analysis work 

has already been performed by the ORM WG to prepare for the eventuality where the 

ORM is needed to provide accessibility for Orbiter repairs. It is equally clear that several 

critical items of analytic open work, the execution of which reduces ORM uncertainty, 

will need to be completed prior to safely invoking the ORM operationally. In addition to 

the known list of open analysis work, recommendations have been formulated, and 

captured in this report, for specific additional analyses and model/simulation validations 

steps to be performed before the first use of the ORM is undertaken. 

Equally clear to the team is that the definition and implementation of critically needed 

operational on-orbit safeguards/checks for the ORM are lagging the analysis. These 

operational safeguards/checks would support the necessary real time on-orbit analysis, 

performance monitoring, and dynamic behavior during both the maneuver of the Orbiter 

and during the repair process. The team has therefore formulated a set of operationally 
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related recommendations that, when completed, will also have the positive effect of 

reducing ORM uncertainty. 

It is the team’s position that the above set of five NESC prioritized recommendations 

represents the minimum set of ORM analytical and operational planning tasks, needed to 

be implemented, in order for the ORM to be considered as a viable contingency for the 

STS-114 mission. Furthermore, the team’s position is that ORM contingency operations 

should not be invoked until, at a minimum, all five of the above prioritized 

recommendations have been addressed by the SSP. 

Taken together, team’s analytical and operational recommendations represent the best set 

of the “necessary conditions” needed to reduce ORM uncertainty prior to first use. Given 

that the Peer Review team performed only a cursory review of the ORM status it would 

be inappropriate and presumptuous to claim that our recommendations represent the 

complete set of “sufficient conditions” for a successful ORM. Along these lines the team 

recommends that a full-time ORM WG Lead Engineer be named to prioritize the known 

open work prior to launch and to be in a position to identify unknown issues/problems as 

they emerge. 

Comment on the Project’s OBSS Alternative to the ORM 

Note that JSC has also identified, and is currently investigating, the feasibility of using 

the Orbiter Boom Sensor System (OBSS) 50-foot boom extension to the SRMS as an 

alternative method of accessing 100 percent of the TPS tiles. The NESC team did not 

assess the details of this OBSS alternative as part of this 8-10 June 2005 peer review. The 

team was however exposed to some of the OBSS Project approach to assessing the OBSS 

alternative and its pros/cons relative to the ORM. 

Based upon only the limited information presented, the team’s viewpoint is, provided the 

EVA astronaut on the end of the OBSS boom has sufficient dynamic stability to effect 

repairs, this OBSS alternative intrinsically appears to be a significantly lower risk 

contingency operation compared to the ORM. The team observed that many of the same 

individuals supporting the ORM are also supporting the OBSS feasibility assessment 

activity and many of the same analytical tools, models, and simulation techniques are 

being employed. It is likely, therefore, that many of the NESC’s ORM recommendations 

may be applicable to the OBSS alternative. 

The team would like to thank the entire ORM WG and the ORM leads, Ladonna Miller 

and Curt Larsen from the SSP and Bill Spetch from the ISS Program, for their openness 
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and frank dialog throughout our consultation activity. This was much appreciated and 

was crucial in NESC getting a good understanding of the ORM analyses, plans and 

potential risks.
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5.0 Consultation Plan 

The NESC initially became involved in the ORM in March 2004 when LaRC engineers 

expressed concerns over the complex dynamics and control of the Orbiter and ISS during 

the proposed ORM operation. The NESC Review Board (NRB) acted to formally 

authorize a Peer Review Consultation on the ORM (04-034-E - ISS/Shuttle Flip 

Maneuver for TPS Repair) and the GN&C NESC Discipline Expert (NDE) conducted an 

initial Peer-Review of the ORM WG modeling and analysis efforts at JSC in August 

2004. Since that time members of the NESC GN&C SPRT have maintained oversight of 

ORM development progress via the weekly ORM WG telecons. In April 2005, a detailed 

NESC status report of the ORM was presented to the NRB by Frank Bauer (see 

Appendix D). Subsequently the ORM was added to the NESC’s “STS-114 Return to 

Flight (RTF) Constraints – Open Work” list as a Red item (which is defined as 

“Technical Solution in Development”) to be tracked and reported on as part of NESC’s 

RTF pre-launch presentations at the SSP Flight Readiness Review (FRR), Shuttle Safety 

and Mission Assurance Readiness Review (SMARR), and other related reviews. The 

NRB also agreed upon the SPRT’s recommendation to perform another Peer Review 

Consultation prior to the launch of STS-114. Planning and negotiation meetings were 

held between the SSP and NESC in May 2005 to define the scope/content of the Peer 

Review and to set a mutually agreeable date for holding this review (June 8-10 2005). 

The motivation for the peer review was derived from NESC’s concern that ORM 

represents new and unfamiliar operations that are complex and pose risks (both known 

and unknown) to the crew and flight systems. The team’s approach to performing this 

most recent ORM peer review was twofold. The team first reviewed the ORM from a 

“big picture” systems-level viewpoint to determine, to the extent a short duration review 

such as this would permit, if the ORM WG missed any key aspects of the problem. Then 

as a follow-up, the team investigated key technical areas to evaluate the depth and 

completeness of some of the ORM WG’s analysis, modeling and simulation work. 

Specific objectives of the NESC ORM Peer Review were: 

1) To assess the breadth of the ORM technical solution at a systems–level. 

 

2) To assess the status, depth, and completeness of the ORM pre-launch modeling, 

simulation and analysis work performed to date. 

3) To determine what ORM work remains to be completed. 
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4) To assess the ORM operational readiness for STS-114. 

5) To understand the risks associated with performing the ORM and determine if 

there are any “showstoppers.” 

 

6) To determine if the ORM WG was proceeding down the path towards a 

successful ORM. 

The purpose of the ORM Peer Review Team was to investigate the models, methodology, 

and overall use of the ORM as a safe repair method. The specific topics covered during 

the NESC ORM Peer Review Process, over the period 8-10 June 2005, are identified in 

the review agenda provided for reference in Appendix B. 
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6.0 Description of Problem, Proposed Solutions, and Risk Assessment 

The JSC driver for developing the ORM contingency capability is unambiguous. The 

ORM represents one possible solution to the problem that the majority (approximately 60 

percent) of the TPS tile acreage is unreachable by the SRMS alone, or even in 

combination with the SSRMS, when the Orbiter is docked to ISS. (See Figure 4.0-1) The 

ORM has been designed and developed to position the Orbiter such that 100 percent of 

the TPS tile is within reach of an EVA astronaut on the SSRMS. 

The ORM is a complex contingency operation that cannot be fully validated on the 

ground prior to first use. Moreover, the ORM is a “first of a kind” operation whose 

execution will require both the flight hardware and the crew to operate in a non-standard 

manner that is significantly outside the nominal operational experience regime. For 

example, consider that normally, the SRMS lifts and deploys payloads with mass and 

inertias much less than the Orbiter. In all operational cases to-date, the Orbiter can be 

thought of as an “infinite mass” that reacts against the much smaller payload mass. The 

SRMS uses this “infinite” reactive mass to help move the payload in the proper position 

(translation and orientation). However, for the ORM, the Orbiter effectively becomes the 

payload that reacts against the more massive ISS. It should be noted that the largest 

payload manipulated by the SRMS to-date has been the 48,000 pound FGB. The FGB 

mass is approximately an order of magnitude less than the Orbiter’s mass of 

approximately 240,000 pounds. Extending SRMS robotic operations from a FGB-class 

payload to the Orbiter, as the payload, is a significant extrapolation. In December 2004, 

the SRMS was certified for Heavy Payload mass operations, following an extensive 

series of low-speed robotic joint ground tests and associated servo-loop model updates. If 

invoked the ORM would be the first SRMS “Heavy Payload” operation. The ORM would 

also be the first use of the SRMS for undocking the Orbiter from the ISS. 

It is important to recognize that “ORM” is a broad term that covers the end-to-end 

operation of undocking/maneuvering the Orbiter, via the SRMS, to the repair position, 

the subsequent Orbiter/EVA astronaut dynamic (relative motion) interactions at the repair 

worksite, and the maneuvering and redocking of the Orbiter following completion of the 

repairs. The ORM is a relatively long duration (3 days), multi-step process that begins 

with the Orbiter docked to the ISS and, from a dynamics and control perspective, entails 

the following specific events: 

1) Grappling of ISS by the SRMS. 

2) SRMS controlled undocking of the Orbiter from ISS. 
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3) Transitioning ISS from nominal CMG-based momentum management control to 

 thruster-based attitude hold control. 

 

4) Maneuvering of the Orbiter, via the SRMS, to an interim Overnight Park Position. 

5) Transitioning ISS from thruster-based attitude hold control to CMG-based 

 momentum management control. 

6) Maintaining the Orbiter/ISS stack in the Overnight Park Position. 

7) Maneuvering of the Orbiter, via the SRMS, from the Overnight Park Position to the 

 repair position with the ISS under Thruster-based attitude hold control. 

8) Providing a sufficiently stable repair worksite environment, with the ISS under CMG 

 based momentum management control, to permit the required tile or RCC repair by 

 EVA astronauts positioned on the SSRMS affixed to ISS. 

9) Post-repair maneuvering and re-docking of the Orbiter. 

Figure 4.0-2 depicts the Orbiter at the ORM overnight park position while Figures 4.0-3 

and 4.0-4 illustrate the Orbiter at the ORM repair position. 

Early on in the ORM dynamics and controls analysis process, the JSC GN&C team 

concluded that the existing as-is ISS CMG-based attitude control system did not have 

sufficient capability/authority to stabilize the various stack configurations during the 

SRMS maneuvering of the Orbiter through the multiple waypoints. During the ORM, the 

ISS GN&C system alone is used to control the attitude of the entire ISS/Orbiter stack. 

The Orbiter GN&C system is in a passive state (with its control actuators not enabled), 

and it is not used to control the dynamics of the stack. In order to provide adequate 

attitude control of the ORM stack configurations from Waypoints 1-13, a new ORMspecific controller and operational mode was designed by the JSC GN&C team to 

provide stable operational performance. This new GN&C operational mode, referred to 

as the USTO mode, uses the existing US CMG PD control law algorithm to only 

command, using a pulse width modulated implementation, the Russian thrusters. 

Thrusters were selected over the CMG’s, as the desired ORM control actuators in order 

to provide good attitude control performance, while achieving acceptable Orbiter relative 

motion with respect to the ISS. 
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Effectively, the normal control torque command, generated by the CMG PD controller is 

converted to a momentum change command (by multiplying it with the PWM period) 

and then sent to the RS SM, where specific thrusters are fired for specific on-times in 

order to achieve the requested momentum change. At the same time the CMG actuator 

torque command is set to zero. Hence, the CMG’s are not used during ORM 

maneuvering of the Orbiter to generate attitude control torques. Functionally, this mode is 

mechanized in the ISS GN&C flight software, by enabling the existing CMG Thruster 

Assist (TA) mode with its CMG control torque limit parameter set to zero, and by setting 

the parameter defining the minimum time between CMG desaturations (i.e., CMG 

momentum unloading via thruster firings) equal to the PWM period. 

The ORM is an operation with high levels of uncertainty involving close proximity 

movements of flight structures, limited back-out opportunities and visibility, and high 

potential for adverse Control-Structure Interaction (CSI) between control systems, 

possibly resulting in large or unstable relative motion between the Orbiter repair 

worksite, the EVA Astronauts positioned on the SSRMS, and the ISS. 

The ORM presents a very challenging system-level modeling, simulation and problem - a 

multi-disciplinary ORM WG and operations organization at JSC. The ORM WG 

provides a much needed forum for coordination and exchange of information between the 

various organizations performing analysis. Although no new hardware is being 

developed for the ORM, the analyses required to ensure the feasibility and safety of this 

repair option present a tremendous analysis integration challenge 

 Note that JSC has also identified and is currently investigating the feasibility of using the 

OBSS 50-foot boom extension to the SRMS as an alternative method of accessing 100 

percent of the TPS tiles. The NESC team did not assess the OBSS option but, provided 

the EVA astronaut on the end of the OBSS boom has sufficient dynamic stability to 

effect repairs, this OBSS alternative intrinsically appears to be a significantly lower risk 

contingency operation compared to the ORM. 
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7.0 Data Analysis 

The NESC team did not perform any independent analysis, modeling, or simulation of 

the ORM dynamics and controls as part of this peer review process. 
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8.0 Findings and Recommendations 

8.1 Findings 

Based upon the data/information conveyed during our meetings at JSC over the period 8-

10 June 2005 the ORM Peer Review Team compiled the following findings: 

F-1 There is a considerable amount of critical open work, in both the ORM analytical 

and operational planning areas, that absolutely must be completed prior to first 

use of ORM. These key pieces of open work, not in priority order, are listed in 

Table 8.1-1. 

F-2 While many of the ORM technical analyses appear to be quite comprehensive 

with sufficient depth/rigor, it is not apparent that all the results of these analyses 

have been very well integrated and used to systematically drive the development 

of all the necessary ORM flight/ground operations plans and procedures. The 

most likely reason for this situation is that there appears to be no single person 

tasked with coordinating/managing the overall effort on a full-time dedicated 

basis. It is the team’s position that the lack of a dedicated full time ORM Lead 

Engineer has impacted, and continues to impact, the integration and prioritization 

of open ORM analytical and operational planning work. A full-time ORM Lead 

Engineer, with a system-wide perspective, is critically needed to both prioritize 

and schedule completion dates for all remaining ORM open work based upon 

negotiated agreements with appropriate resource managers. 

F-3 The ORM is an operation that the SSP recognizes as complex and risky. The SSP 

is actively studying the risk trades for accessing a repair worksite using ORM as 

well as other access methods. Currently, the SSP is considering, in descending 

hierarchical order, three alternative methods of gaining access to TPS tile and 

RCC repair worksites: 

1) access by use of SRMS/ SSRMS robotic arms, 

 

2) access by use of the SRMS with the OBSS 50-foot boom attached, and 

 

3) ORM access. The on orbit contingency decision flow process/policy 

 defining specifically when the ORM will be operationally invoked was 

 pending on the results of the previously mentioned risk trades and had not 

 been finalized by the SSP at the time of the peer review. 
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F-4 GN&C ORM analyses indicate that the smallest phase margins for the ISS USTO 

controller can go as low as 4.5 degrees. This very low phase margin occurs at the 

Waypoint 9 position using the “perturbed” dynamic model, where a 20 percent 

uncertainty is included for both modal frequencies and modal amplitudes, with a 

2-second delay in execution of the thruster commands. Likewise, the phase 

margin for the overnight parking configuration is at 5.5 degrees. The frequency 

associated with these margins is at 0.016 Hz, which is close to the Nyquist 

frequency (0.025 Hz). The proximity of the flexible mode to the Nyquist 

frequency, as well as the fact that in this particular control system design the 

flexible modes below 0.04 Hz are phase stabilized, raise stability robustness 

issues in view of model uncertainties in modal frequencies, damping, etc. 

Moreover, aliasing effects may become a problem and need to be considered. The 

team’s position is that these very low phase margins are not acceptable given that: 

a) the ORM is a first-of-a-kind maneuver, 

b) there is limited experience with a USTO type controller that combines a US 

 controller with the Russian thrusters, 

c) the on/off control of the thrusters is implemented via a Pulse Width Modulator 

 (PWM) such that the exact time for the execution of a thruster firing is 

 variable and depends on the command levels, and 

d) that effects of sensor dynamics, as well as some discretization effects, do not 

 seem to have been included in the GN&C ORM analyses. 

The belief that these low phase margins, which are based on a linear model of the 

SRMS, are overly conservative is not a sufficient basis to proceed with the current 

USTO controller design. It is the position of the team that the ISS controller 

stability margins must either be re-computed with a high fidelity model (which 

includes the 20 percent variation in modal frequencies of the SRMS as well as 

appropriate modal damping/amplitude uncertainties), and shown to be adequate, 

or a new/modified ISS attitude controller design must be developed and 

incorporated. 

F-5 The ability of the rate-damping controller to recover the stack from a free drift (at 

maximum nominal angular velocities) at either of the parking positions (both the 

overnight park and repair waypoints), is not fully clear to the team. This is 

equally the case for any of the waypoints for which the analysis has indicated that 
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direct recovery without reorienting the SRMS, is not possible. Additionally, there 

are some maneuver waypoints for which the analysis has indicated the direct 

recovery from free drift rate buildup (resulting from a loss of ISS attitude control) 

is not possible without a reorientation of the SRMS. For example, analysis has 

shown it is not possible for the ISS rate-damping controller to recover the stack, 

from maximum free drift angular velocities, at either of the overnight park 

position waypoint or the repair position waypoints. The general finding here is, 

therefore, if the ISS loses attitude control during the ORM the Orbiter may, 

depending on which maneuver waypoint it is at or which two waypoints it is 

between, have to be reoriented with the SRMS back to a recoverable waypoint 

before ISS attitude control can be restored. The implication is that failure of the 

SRMS during ORM such that the Orbiter cannot be reoriented, depending on the 

orientation at the time of failure, could preclude 

a) rebirthing of the Orbiter to the ISS and recovery of the Orbiter ORM crew, 

b) establishment of a favorable Torque-Equilibrium-Attitude (TEA) ISS attitude 

 control with the Orbiter attached, 

c) re-establishment of ISS attitude control From free-drift if the ISS attitude 

 control goes off-line, and/or 

d) Orbiter separation from the ISS for redocking. 

F-6 The ORM WG’s ability to reuse models from their legacy TRICK simulation 

library environment, and their incremental “build-then-test” approach for the 

ORM simulation development, were both viewed by the team as being very 

positive and impressive. Their use of heritage models, recognizing that they are 

operating well out of the experience range and used Kane’s equations to 

independently verify the work, were all very positive. The matching results from 

the independent comparison check of the newly developed (by the ER Robotics 

Engineering organization) integrated ORM simulation (which represents a rigid 

Orbiter, a flexible SRMS and a rigid ISS model) in the TRICK simulation 

environment against the functionally equivalent Station/Orbiter Multibody 

Berthing Analysis Tool (SOMBAT)-based simulation (which is an existing 

simulation developed by the EG GN&C engineering organization) is a major step 

in verifying the newly developed ER ORM simulation. However, another critical 

independent simulation cross-check remains to be performed between the ERdeveloped Worksite Dynamics (WSD) Simulation (which represents the complete 

end-to-end system dynamics including ISS flexible dynamics and the EVA 
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astronaut on the SSRMS) and the functionally equivalent EG-developed 

SOMBAT-based simulation. 

F-7 No Contingency Action Plan has been developed for the on-orbit real-time ORM 

WSD analysis. 

F-8 The ORM planned implementation relies heavily on the human-in-loop approach 

to fault detection, isolation, and recovery (FDIR) at the system level. Although 

each element of the stack (ISS, Shuttle, SRMS, and the SSRMS) has their 

respective FDIR systems, the stack as whole will have to rely on the situational 

awareness of the astronauts on the ISS, and on the Orbiter, to assure the health 

and safety of the system. This requires extensive training, and well-defined 

protocols for the astronauts, so that they may act prudently and quickly to 

unforeseen anomalies that may affect this maneuver. The team also found that, 

given the continuous auto-sequenced nature of the SRMS maneuvering of the 

Orbiter, there are no “hold and monitor” steps planned for each SRMS maneuver 

trajectory waypoints beyond Waypoint 1. No clearly defined realtime “Go/No 

Go” ORM maneuver criteria have been developed based upon the collection, 

analysis and monitoring of telemetry/camera video data. 

F-9 Separation of the Orbiter from the ISS during ORM, if required, must be 

performed passively, using orbital dynamics from the overnight park position, 

with the Shuttle/ISS stack pitched down 45 degrees and no Orbiter thruster 

firings. 

F-10 There has been considerable progress in the area of work site dynamics stability 

analysis and modeling. The loads and training testbeds should help greatly to 

characterize the expected loads during the repairs as well as to train the 

astronauts. Preliminary limits on the force level, time duration of the force 

application, and time separation between discrete force applications of the various 

repair loads have been identified for the TPS tile repairs. However, there is a lack 

of detailed understanding on the possibility of repair-induced motions that 

potentially may result in the crew getting injured at the work site or additional 

damage to the hardware. 
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Table 8.1-1. List of ORM Open Work (as of 10 June 2005) 

a) Final and complete definition and agreement on all the worksite dynamics forcing functions 

(force versus time profiles) due to the EVA astronaut repair operations on tile and RCC. 

b) Inclusion of the ISS flexible dynamics in the ER-developed Worksite Dynamics simulation used 

to predict relative motion between the Orbiter and the EVA astronauts. 

c) Independent cross-check comparisons between the ER-developed Worksite Dynamics 

simulation and the functionally equivalent EG-developed SOMBAT-based simulations for a 

representative set of common benchmark test cases. 

d) Simulation, using the ER-developed Worksite Dynamics simulation tool, of the relative motion 

between the Orbiter and the EVA astronauts using the final defined set of repair forcing 

functions. 

e) Analysis and evaluation of the relative motion dynamics to assess repair feasibility. 

f) Additional ORM stability margin simulation and analysis. 

g) Nominal SRMS clearance analysis. 

h) The definition and performance of a common test case, as part of the overall ORM verification 

process, to be used across the 1) VR Lab repair dynamics testbed, 2) the 3-DOF PBAF repair 

dynamics testbed and 3) the end-to-end integrated system dynamics simulation. Common test 

case results from each of the three environments should be compared and any major differences 

reconciled. 

i) Development of an ORM Contingency Action Plan for performing on-orbit realtime ORM 

analysis of specific TPS tile or RCC repair contingencies. 

j) Development of an on-orbit realtime ORM monitoring strategy, plans and procedures. Such 

procedures would be used during the course of actually maneuvering the Orbiter to its repair 

position using the SRMS to evaluate the overall system state-of-health and to do realtime 

assessments of the ORM performance. They will define what specific sensor data will be 

collected and processed to support the realtime monitoring of the ORM performance and the 

health of the combined dynamic stack. 

k) Finalization of the decision flow policy of the repair “access” options that would be employed 

prior to invoking the Contingency Shuttle Crew Support/Launch on Notice (CSCS/LON) 

contingency activity.
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8.2 Recommendations 

The ORM Peer Review team has developed the following prioritized set of 

recommendations which represents the minimum set of ORM analytical and operational 

planning tasks needed to have the ORM in place as a viable contingency for STS-114. 

These prioritized recommendations are summarized, in a top-level fashion, in the STS114 Flight Readiness Review (FRR) ORM chart package which is provided for reference 

in Appendix C. 

R-1 Re-assess the ISS attitude control system design, employed for ORM operations, 

for both stability and performance 

The use of the high-fidelity SOMBAT-based time-domain simulation is 

recommended to show that the current ISS controller design has adequate stability 

robustness margins (i.e. gain and phase margins). Also use the high-fidelity 

simulation to demonstrate performance of ISS rate damping controller to recover 

the ISS/Orbiter stack from free drift rates, on the order of 0.18 degrees/second, at 

either the overnight park position or the repair position 

High fidelity simulations, using the flight-proven SOMBAT, should be used to 

demonstrate that the system, in free drift in each of these configurations, can be 

recovered by moving the SRMS to the nearest recoverable safe point, and 

implementing the rate damping controller. The high fidelity simulation model 

should include the damping and frequency uncertainties associated with the 

SRMS. 

R-2 Complete the independent validation of the ORM integrated end-to-end dynamic 

simulation, to include benchmarking with Virtual Reality (VR) laboratory 

dynamics simulation 

The planned, but as yet unexecuted, independent cross-check comparison runs 

between the ES/ER integrated WSD Simulation and EG-developed SOMBAT 

tool needs to be completed, using a set of common benchmark test cases. This 

particular item is also captured as Open Work item c), but its fundamental 

importance to reducing uncertainty and increasing confidence in the ORM 

modeling merits it being citied as a specific high-priority recommendation. Some 

comparisons already exist, but common end-to-end runs, using the same load 
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inputs, are needed. This work should preferably be completed prior to launch of 

STS-114. 

The ORM WG should define a common benchmark test case, as part of a unified 

approach to the overall ORM modeling/simulation verification process, to be 

performed/conducted across the following three elements: 1) VR Laboratory 

repair dynamics testbed, 2) the 3-Degree of Freedom (DOF) Precision Air 

Bearing Facility (PBAF) repair dynamics testbed and 3) the new ER-developed 

end-to-end integrated system dynamics simulation. Common test case results 

from each of these three environments should be compared and any major 

differences reconciled prior to the first use of the ORM. 

R-3 Complete ORM contingency planning to include definition and development of 

detailed procedures and protocols, especially for ORM abort scenarios. 

ORM contingency planning is critically needed to define: 

a) the ORM state-of-health/dynamic behavior monitoring procedures and 

 protocols, 

b) the specific Contingency Action Plan for performing on-orbit 

 analysis of worksite dynamic interactions, 

c) and, on-orbit pre-repair dynamic checks in the worksite environment and d) 

 FDIR checks/tests. 

Develop a contingency action plan that defines the real-time, on-orbit ORM 

analysis tasks that need to be completed, the people and phone numbers required, 

and the facilities that are necessary to support the ORM realtime analysis. Also, 

prior to launch the ORM realtime Contingency Action Plan needs to be simulated 

with appropriate personnel. Each of the real time models has been run, but there is 

not a case in which the team was asked about specific damage at an arbitrary 

location and then run the tools from beginning to end. This simulation would 

allow Mission Control Center (MCC)/Mission Evaluation Room (MER) users to 

see this process and understand what limitations exist and also understand the 

resulting outputs. At a minimum, a table-top paper simulation should be 

performed, by the ORM WG, of these realtime repair assessments. 

The SSP should consider implementing a hold at each maneuver waypoint to 

allow for realtime assessment of the integrated stack’s dynamics behavior and 
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performance. There needs to be a clear plan and procedure to do realtime 

assessment on how the ORM is progressing from a dynamics perspective. Define 

how, during the course of actually maneuvering the Orbiter to its repair position 

using the SRMS, the flight operations team will determine the overall system 

state-of-health and perform real-time assessments of the ORM performance. 

Define what specific sensor data will be collected and processed to support the 

monitoring of the ORM performance and the health of the combined dynamic 

stack. 

 The FDIR systems in the ISS, shuttle, SRMS, and SSRMS need to be examined 

for any potential conflicts in exercising this maneuver 

Fault scenarios, which describe potential loss of system’s stability, need to be 

identified from the moment of the Orbiter separation, at the start of the maneuver, 

and throughout the maneuver, including at all 13 waypoints. Particular attention 

must be given to the two parking positions. These scenarios include, but are not 

limited to, loss of attitude control due to instabilities as well as hardware failure, 

and excessive and unstable motion of SRMS arms and joint angles. 

Metrics must be developed for assessing the health and safety of the system 

during the overall maneuver and repair. It is advisable to have these metrics at a 

system level and not simply rely on the existing fault detection systems on the ISS 

and SRMS, individually. However, if that is not possible, procedures for 

identifying system level faults must be developed and astronauts must be trained 

to properly implement these procedures. These procedures must support the 

decentralized nature of the fault detection approach. 

Protocols must be developed for each configuration of the stack, during the ORM, 

to define mode switching logic (from USTO to rate damping, for example) as well 

as to define feasible schemes to maneuver to the nearest waypoint for safe 

recovery. These protocols should be implemented as soon as possible once a 

fault/instability is identified. It is best that these protocols are implemented with 

software within an FDIR system. However, if that is not possible, astronauts 

should be trained to implement these protocols in a timely and proper manner. 

 

Given uncertainties in the worksite dynamics, close clearances, and a general 

inability to undo repair mistakes, on-orbit checks of the worksite environment in a 

safe (not likely to lead to impact/damage) location prior to initiating an actual 

repair are recommended. For example, the astronaut can be positioned near the 

repair site and survey motion relative to the site while sitting quiet, performing a 
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layback maneuver, and touching the wing with a mock execution of the repair 

steps. These actions could refine repair operations and optimize likelihood of 

success. 

R-4 Complete the analysis and simulation of the repair worksite dynamic interaction 

(i.e. assess relative motions between the EVA astronaut and Orbiter). 

The ORM WG needs to finalize the complete definition and agreement on all the 

worksite dynamics forcing functions (force versus time profiles) due to the EVA 

astronaut repair operations on both TPS tile and the RCC locations. 

The ORM WG should take the steps necessary to include the modal-significant 

ISS flexible dynamics in the ER-developed Worksite Dynamics simulation used 

to predict relative motions between the Orbiter and the EVA astronauts. While 

some preliminary work has been performed to assess the impact of ISS flexibility, 

it is clear to the team that those results do not provide a sufficient basis to ignore 

the potential impact of ISS dynamic flexibility on relative motions between the 

Orbiter and the EVA astronauts. 

R-5 Fully document and communicate all ORM operational constraints and hazards to 

Astronaut Office and mission control center staff. 

The SSP should define and communicate (or re-communicate, as the case may be) 

an up-to-date summary of all ORM operational constraints, hazards, and risks to 

the flight crew, the Astronaut Office and the mission operations team to ensure all 

those parties are fully aware of the operational implications of loss of ISS attitude 

control during the ORM. 

For example, there is a need to document and communicate the fact that, if 

required during the ORM, an emergency Orbiter separation must be performed 

passively, using orbital dynamics with no thruster firings, from the overnight park 

position with the entire ISS/Orbiter stack attitude pitched down by 45 degrees. 

The SSP should, prior to launch, finalize the decision flow policy of the repair 

“access” options that would be employed prior to invoking the CSCS/LON 

contingency. The SSP should complete its assessment of the feasibility of 

employing the OBSS boom to effect repairs (i.e., primarily to determine if the 

OBSS provides a sufficiently stable base from which to perform the repairs), in a 

time frame to support the establishment of the repair access decision flow policy 

prior to launch of STS-114. 
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It is the team’s position that the above set of five NESC prioritized recommendations, 

represents the minimum set of ORM analytical and operational planning tasks, needed to 

be implemented in order for the ORM to be considered as a viable contingency for the 

STS-114 mission. Furthermore, the team’s position is that ORM contingency operations 

should not be invoked until, at a minimum, all five of the above prioritized 

recommendations have been addressed by the SSP. 
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9.0 Lessons Learned 

This NESC Consultation presented no lessons learned.
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10.0 Definition of Terms 

Corrective Actions Changes to design processes, work instructions, workmanship 

practices, training, inspections, tests, procedures, specifications, 

drawings, tools, equipment, facilities, resources, or material that 

result in preventing, minimizing, or limiting the potential for 

recurrence of a problem. 

Finding A conclusion based on facts established during the 

assessment/inspection by the investigating authority. 

Lessons Learned Knowledge or understanding gained by experience. The experience 

may be positive, as in a successful test or mission, or negative, as 

in a mishap or failure. A lesson must be significant in that it has 

real or assumed impact on operations; valid in that it is factually 

and technically correct; and applicable in that it identifies a 

specific design, process, or decision that reduces or limits the 

potential for failures and mishaps, or reinforces a positive result. 

Observation A factor, event, or circumstance identified during the 

assessment/inspection that did not contribute to the problem, but if 

left uncorrected has the potential to cause a mishap, injury, or 

increase the severity should a mishap occur. 

Problem The subject of the independent technical assessment/inspection. 

Recommendation An action identified by the assessment/inspection team to correct a 

root cause or deficiency identified during the investigation. The 

recommendations may be used by the responsible C/P/P/O in the 

preparation of a corrective action plan. 

Root Cause Along a chain of events leading to a mishap or close call, the first 

causal action or failure to act that could have been controlled 

systemically either by policy/practice/procedure or individual 

adherence to policy/practice/procedure. 
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11.0 List of Acronyms 

CMG Control Moment Gyroscope 

CSCS Contingency Shuttle Crew Support 

CSI Control-Structure Interaction 

dB Decibel 

DOF Degree of Freedom 

EG Aeroscience and Flight Mechanics Engineering 

Division at JSC 

ER Robotics Engineering Division at JSC 

EVA Extra Vehicular Activity 

FDIR Fault, Detection, Isolation, and Recovery 

FGB Functional Energy Block 

FRR Flight Readiness Review 

GN&C Guidance, Navigation & Control 

Hz hertz 

ISS International Space Station 

JSC Johnson Space Center 

LON Launch-on-Need 

MCC Mission Control Center 

MER Mission Evaluation Room 

MM Momentum Management 

NDE NESC Discipline Expert 

NESC NASA Engineering & Safety Center 

NRB NESC Review Board 

OBSS Orbiter Boom Sensor System 

ORM Orbiter Repair Maneuver 

PABF Precision Air Bearing Facility 
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PD Proportional-Derivative 

PWM Pulse Width Modulation 

RCC Reinforced Carbon-Carbon 

RS Russian Segment 

RTF Return-to-Flight 

SM Service Module 

SMARR Safety & Mission Assurance Readiness Review 

SOMBAT Station/Orbiter Multibody Berthing Analysis Tool 

SPRT Super Problem Resolution Team 

SRMS Shuttle Remote Manipulator System 

SSP Space Shuttle Project 

SSRMS Space Station Remote Manipulator System 

TEA Torque Equilibrium Attitude 

TPS Thermal Protection System 

USTO United States Thruster-Only 

VR Virtual Reality 

WG Working Group 

WSD Worksite Dynamics 
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12.0 Minority Report 

There are no dissenting opinions in this report. 
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Volume 2: Appendices 

Appendix A. NESC ITA/I Request Form (NESC-003-FM-01) 
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Appendix B. NESC ORM Peer Review Agenda (8-10 June 2005) 

NESC ORM Peer Review Agenda

(6 June 2005) 

All personnel listed are the team leads and responsible for 

assuring other team members, as appropriate, are in 

attendance. 

Day1 - Wednesday, June 8th 

Meeting Location: Building 16, Room 1123A

8:45 am to 9:00 am 

Introductions & Review Objectives/Guidelines 

(Frank Bauer) 

9:00 am to 11:00am 

ORM Status Update, Technical Overview, Analysis Approach and Open Work 

(Curt Larsen/MO2 and Bill Spetch/OM5) 

11:00 am to 12 noon 

Discussion of the Integrated Simulation architecture (aka the "Common Sim") 

(Les Quiocho/ER7) ** subject to move** 

1pm to 2:30 pm

Worksite Dynamics 

(Sean Cupitt/Lora Bailey/Kwun Siu (Ki)/Dina Barclay 
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2:30 pm to 5:00 pm 

Discussion of SRMS and SSRMS Dynamic Analysis Results 

(Liz Bains/ER7) 

5:00 pm to 6 pm

NESC Team Caucus: Recap of Day 1 and Re-Plan for Day 2 

Day 2 - Thursday, June 9th 

Meeting Location: Building 4S, Room 1200

9:00 am to 10:30 am 

Discussion of ISS GN&C (MM/AH) ORM Analysis Results 

(Louis Nguyen/EG3) 

10:30 am to 12:00 noon 

Discussion of Independent Modeling and Simulation Plans/Results 

(Louis Nguyen/EG3) 

1:00 pm to 3:00 pm

SRMS/APAS Operations 

(Tim Briscoe/ES2) 

3:00 pm to 5:00 pm

Discussion of ORM Risks/Fault Tolerance (Probability vs. Impact) 

(Todd Miller/NC) 

5:00 pm to ?pm

NESC Team Caucus: Recap of Day 2 and Wrapup. (Also planning for Day 3 

meetings)

Day 3 - Friday, June 9th

8:00 am to 10:00 am 

Meeting Location - Building 1, Room 720 

Question and Answer session for all ORM WG members

(all WG members) 

Note: This portion of 

the Peer Review did not 

take place. 
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10:00 am to 12:00 noon (IF NEEDED) 

Meeting Location - Building 1, Room 715F 

Wrapup 

(Curt Larsen and Bill Spetch)
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Appendix C. ORM STS-114 FRR Chart Package 

(dated 27 June 2005) 
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NESC Request No. 04-034-E 

This briefing is for status only and does not represent complete engineering data analysis 1

28-29 June 05 Shuttle/ISS Orbiter Repair Maneuver

• Description and Scope:

– In response to concerns over the 

complex dynamics and control of 

the Orbiter and ISS during the 

Orbiter Repair Maneuver (ORM) 

the NESC GN&C SPRT 

conducted a pre-RTF Peer 

Review of the ORM Working 

Group’s modeling and analysis 

efforts at JSC on 8-10 June 2005

Dennehy

04-051-E

• Background 

– ORM is a complex contingency operation with close proximity movements 

of flight structures, limited back-out opportunities and visibility, and high 

potential for adverse dynamic interactions between control systems, 

SRMS, SSRMS, and structure, possibly resulting in large or unstable 

relative motion between the Orbiter, the EVA Astronauts, and the ISS

This briefing is for status only and does not represent complete engineering data analysis 2

28-29 June 05 Shuttle/ISS Orbiter Repair Maneuver

• Background (continued)

• ORM consists of new and unfamiliar operations that are complex and pose risks 

(both know and unknown) to the crew and flight systems. 

• ORM is a “first of a kind” operation whose execution will require both the flight 

hardware and the crew to operate in a non-standard manner in regimes that are 

significantly outside the nominal operational experiences.

• Results:

– NESC White Paper Report developed summarizing ORM Peer Review findings and 

recommendations 

– Peer review team consensus is that there remains critical open work that 

absolutely must be completed prior to first use of ORM 

– The team also found that that lack of a dedicated full time ORM Lead System 

Engineer has impacted, and continues to impact, the integration and prioritization 

of open ORM analytical and operational planning work

– The team found that the on-orbit contingency decision flow process/policy 

defining specifically when the ORM will be invoked had not been finalized 

– The team has developed the following prioritized set of recommendations which 

represents the minimum set of ORM analytical and operational planning tasks 

needed to have the ORM in place as a viable contingency for STS-114

04-051-E

Dennehy
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This briefing is for status only and does not represent complete engineering data analysis 3

28-29 June 05 Shuttle/ISS Orbiter Repair Maneuver

• Results (continued):

• Prioritized set of NESC recommendations on the ORM:

- #1 Priority: Re-assessment of ISS attitude control system design and 

performance. Use high-fidelity simulation to show current design has 

adequate stability robustness margins. Also use high-fidelity 

simulation to demonstrate performance of ISS rate damping controller 

to recover stack from free drift rates at either the overnight park 

position or the repair position 

- #2 Priority: Complete the independent validation of the ORM 

integrated end-to-end dynamic simulation, to include benchmarking 

with Virtual Reality (VR) laboratory dynamics simulation 

- #3 Priority: Complete ORM contingency planning to include definition 

of: a) the ORM state-of-health/dynamic behavior monitoring 

procedures and protocols, b) the specific Contingency Action Plan for 

performing on-orbit analysis of worksite dynamic interactions, c) onorbit pre-repair dynamic checks in the worksite environment and d) 

Failure Detection, Isolation and Recovery (FDIR) checks/tests 

04-051-E

Dennehy

This briefing is for status only and does not represent complete engineering data analysis 4

28-29 June 05 Shuttle/ISS Orbiter Repair Maneuver

• Results (continued):

- #4 Priority: Complete the analysis and simulation of the repair worksite dynamic 

interaction (i.e. assess relative motions between the EVA astronaut and Orbiter)

- #5 Priority: Fully document and communicate all ORM operational constraints 

and hazards to Astronaut Office and mission control center staff

- For example, need to document and communicate the fact that, if required 

during the ORM, an emergency Orbiter separation must be performed 

passively, using orbital dynamics with no thruster firings, from the overnight 

park position with the entire stack pitch down 45 degrees 

04-051-E

Dennehy

• Issues/constraints/open work:

– The set of five NESC prioritized recommendations, representing the minimum set of 

ORM analytical and operational planning tasks, need to be implemented in order for 

the ORM to be considered as a viable contingency for STS-114

• Flight Rationale/ Risk Assessment:

• ORM contingency operations should not be invoked until, at a minimum, all 

NESC prioritized recommendations have been addressed
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NESC Request No. 04-034-E 

Appendix D. April 2005 ORM Status Report 

Status Report 

Orbiter Repair Maneuver (a.k.a. Orbiter “Flip” Maneuver) 

Frank H. Bauer, NESC GN&C SPRT 

3/31/05 

The intent of this report is to provide a status on the NASA JSC initiative to perform a 

series of re-orientation maneuvers on the Space Shuttle using the Space Shuttle Remote 

Manipulator to support Orbiter Repair. The primary requirement for this very 

challenging maneuver is to inspect remote portions of the RCC and ceramic tile for 

damage and, if damage is observed, to enable vehicle repair. Repair would be 

accomplished by undocking from the ISS using the Shuttle RMS, reorienting the Shuttle 

using the Shuttle RMS and then allowing astronauts on the Space Station Remote 

Manipulator to complete the repair. It should be noted that this specific maneuver will 

only be required for a small subset of the RCC and ceramic tile repair scenarios. 

Executive Summary

Several members of the NESC Guidance, Navigation and Control SPRT have been 

providing high-level oversight of the technical and programmatic activities surrounding 

the Orbiter Repair Maneuver since July 2004. Members of the SPRT attended a 

comprehensive NESC review at NASA JSC on August 31-Sept 2, 2004. In addition, as 

time permits, SPRT team members participate in the ORM weekly teleconferences, get 

periodic status updates from JSC-resident SPRT members Louis Nguyen and Tuyen Hua, 

they review material on the ORM web site, and Frank Bauer, the out-going GN&C NDE, 

has performed face-to-face status discussions with the ORM Shuttle Program Office 

leads Ladonna Miller and Curt Larsen. 

The ORM activity represents a challenging control-structure interaction problem. 

Normally, the Shuttle RMS lifts and deploys payloads with mass and inertias much 

smaller than the Shuttle. In all cases to-date, the Shuttle can be thought of as an “infinite 

mass” that reacts against the much smaller payload. The Shuttle RMS uses this “infinite” 

reactive mass to help move the payload in the proper position (translation and 

orientation). However, for the ORM, the Shuttle becomes the payload that reacts against 

the ISS. It should be noted that the largest payload attached to the Shuttle RMS to-date is 

the FGB. The FGB mass is approximately an order of magnitude less than the Shuttle 
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NESC Request No. 04-034-E 

mass. So extrapolation from an FGB payload to the Shuttle as a payload is a quite 

daunting challenge. 

It is the NESC team’s opinion that the ORM team are currently on the right path to 

analytically validate the viability of whether this end-to-end system can successfully 

perform an ORM; however, the initiative is proceeding much slower than anticipated. 

The primary cause of this delay resulted from the engineering community (i.e. EG, ER 

and ES) needing to prioritize their human resources on primary Shuttle Return to Flight 

(RTF) initiatives. Now that sufficient resources are available to move forward, ORM 

end-to-end analysis has begun in earnest to assess the stability of the system (Shuttle, 

SRMS, etc.) while under the influence of worksite dynamic interaction (crew motion and 

vehicle repair). 

Specific major ORM-related activities performed to date, with NESC team 

recommendations on these follow: 

1) ISS Russian Segment Maneuver Control System Modification---requires a 

new thruster control system (phase plane parameter changes and development of 

“cyclogram”) to minimize Shuttle RMS brake slip. ISS controller modifications 

have been developed and have been tested on-orbit. NESC GN&C SPRT 

comments: Good first step in ORM development 

2) ORM Detailed Test Objective (DTO)---a DTO was planned for STS-121 (2nd

flight of shuttle after return to flight) while docked to the ISS. The intent of this 

DTO was to validate some aspects of the ORM activity, particularly specific 

Shuttle RMS orientations with the Shuttle acting as the payload. This DTO was 

not approved by the Joint Shuttle/ISS Program Office due to concerns regarding 

mission risk and analytic maturity. The NESC team was following this initiative 

quite closely. The NESC team was quite concerned about proceeding forward 

with this DTO, given the analytic maturity and mission (ISS and Shuttle) risk. 

They concur with the Program Office decision on this matter. 

3) Worksite stability---models of crew member dynamics and repair dynamics are 

currently being developed. The end-to-end analysis of the entire system (Shuttle 

Controller, ISS Controller, Shuttle RMS controller, Station ISS controller and 

worksite dynamics) has not been completed to date. NESC reaction: Obviously, 

these analyses need to be completed before the ORM can be contemplated for use. 

Once the analyses are complete, the NESC team would like to have a second 

comprehensive review of the analysis efforts, similar to the depth provided at the 

August 2004 meeting. Given that this maneuver and subsequent repair have the 
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potential for catastrophic loss of the Shuttle and ISS, plans to independently 

validate these models are recommended by the NESC prior to their use. 

4) Contingency decision to use of ORM during future Shuttle missions---given 

that the ORM has yet to be validated, there is significant concern within the 

NESC GN&C SPRT that, in the event that a Shuttle tile problem is observed, a 

go-ahead to proceed with the ORM may be operationally invoked. The NESC 

GN&C team does not support this given the immature state of the analyses. 

Further, we have recently learned that ORM contingency procedures are in place 

for STS-114. It is our recommendation to the NESC Review Board that the ORM 

contingency operations procedures not be invoked until the system validation is 

complete and the NESC has concurred with the validation and contingency 

operations plan. 

The above represents an executive summary of the ORM plans and NESC GN&C SPRT 

thoughts and recommendations to date. This team will continue to monitor the progress 

of the ORM activities and report back to the NESC as appropriate. If more detailed 

discussions on this topic are required, please contact Frank Bauer at 

frank.bauer@nasa.gov or 202-358-0897. Additional background material is shown on 

the next few pages. 

The NESC GN&C SPRT would like to thank the entire ORM team and the ORM leads, 

Ladonna Miller and Curt Larsen from the Shuttle Program Office and Bill Spetch from 

the ISS Program Office, for their openness and frank dialog throughout our oversight 

activity. This was much appreciated and was crucial in getting a good understanding of 

the ORM analyses, plans and potential risks. 

<signed> 

Frank H. Bauer 

NESC GN&C SPRT 
NASA Engineering and Safety Center 

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NESC Request No. 04-034-E 

Approval and Document Revision History 

Approved: Original signed on file 8-8-05

 NESC Director Date 

Version Description of Revision Office of Primary 

Responsibility 

Effective 

Date 

1.0 Initial Release Principal Engineer’s 

Office 

8-8-05 
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

2. REPORT TYPE 

Technical Memorandum

 4. TITLE AND SUBTITLE

International Space Station/Shuttle “Flip” Maneuver for Thermal 

Protection System Repair Consultation Report

5a. CONTRACT NUMBER

 6. AUTHOR(S)

Dennehy, Cornelius J.; Bauer, Frank; Bilimoria, Karl D.;

Dillman, Dennis B.; Gilbert, Michael G.; Hagopian, Michael; Hua, Tuyen; 

Leggett, Jay A.; Maghami, Peiman G.; Mangus, David J.; Starin, Scott R.

 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NASA Langley Research Center

Hampton, VA 23681-2199

 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

 8. PERFORMING ORGANIZATION

 REPORT NUMBER L-19649

NESC-RP-05-88/04-034-E

10. SPONSOR/MONITOR'S ACRONYM(S)

NASA

13. SUPPLEMENTARY NOTES

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

Subject Category: 16

Availability: NASA CASI (443) 757-5802

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email: help@sti.nasa.gov)

14. ABSTRACT

The intent of this Technical Consultation Report is to document the finding and recommendations of the NESC Orbiter Repair 

Maneuver (ORM) Peer Review conducted at NASA’s Johnson Space Center (JSC) with the ORM Working Group (WG) over 

the period 8-10 June 2005.

15. SUBJECT TERMS

EVA; FlipManeuver; ORM; RCC; SSRMS; TPS

18. NUMBER

 OF 

 PAGES

57

19b. TELEPHONE NUMBER (Include area code)

(443) 757-5802

a. REPORT

U

c. THIS PAGE

U

b. ABSTRACT

U

17. LIMITATION OF 

 ABSTRACT

UU

Prescribed by ANSI Std. Z39.18

Standard Form 298 (Rev. 8-98)

3. DATES COVERED (From - To)

Mar. 2004-July 2005

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

869021.06.07.03.99

11. SPONSOR/MONITOR'S REPORT

 NUMBER(S)

NASA/TM-2009-215710

16. SECURITY CLASSIFICATION OF:

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shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

1. REPORT DATE (DD-MM-YYYY)

01- 04 - 2009