American National Standard - American Institute of ... S-120A-201X Draft for Public Review American National Standard Mass Properties Control for Space Systems Sponsored by American

ANSI/AIAA S-120A-201X

Draft for Public Review

American National Standard

Mass Properties Control for Space Systems

Sponsored by

American Institute of Aeronautics and Astronautics

and International Society of Allied Weight Engineers, Inc.

Approved XX Month 2015

American National Standards Institute

Abstract

Mass properties control is a critical aspect of space system development. This standard and International

Society of Allied Weight Engineers, Inc., RP A-3, Recommended Practice for Mass Properties Control for

Space Systems, together define terminology and establish uniform processes, procedures, and systematic

methods for the management, control, monitoring, determination, verification, and documentation of mass

properties during the development, design, and operational phases of space systems, including their

components and subsystems. This standard and the recommended practice apply to space vehicles, upper

stage vehicles, injection stages, payloads, reentry vehicles, launch vehicles, and ballistic vehicles. This

standard is intended to convey minimum requirements applicable to space system development, while the

recommended practice is intended to be used as a reference for the development of a project-specific,

contractually required mass properties control plan.

ANSI/AIAA S-120A-2015

ii

Published by American Institute of Aeronautics and Astronautics 1801 Alexander Bell Drive, Reston, VA 20191

Copyright © 2015 American Institute of Aeronautics and Astronautics All rights reserved No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher.

Printed in the United States of America


iii

Contents

Foreword ........................................................................................................................................................................ v

1 Scope .................................................................................................................................................................... 1

2 Tailoring................................................................................................................................................................. 1

3 Applicable Documents ........................................................................................................................................... 1

4 Vocabulary ............................................................................................................................................................ 1

4.1 Acronyms and Abbreviated Terms .................................................................................................................... 1

4.2 Terms and Definitions ....................................................................................................................................... 3

5 Requirements ........................................................................................................................................................ 7

5.1 Mass Properties Control.................................................................................................................................... 7

5.2 Analysis ........................................................................................................................................................... 14

5.3 Verification ...................................................................................................................................................... 16

5.4 Mass Properties Data Management ................................................................................................................ 18

5.5 Documentation ................................................................................................................................................ 19

6 Bibliography .................................................................................................................................................... 20

Annex A Supplemental Information for Terms and Definitions (Informative)......................................................... 21

A.1 Mathematical Descriptions .............................................................................................................................. 21

A.1.1 Mass ........................................................................................................................................................... 21

A.1.2 Center of Mass ........................................................................................................................................... 21

A.1.3 Moment of Inertia ........................................................................................................................................ 21

A.1.4 Product of Inertia ........................................................................................................................................ 21

A.1.5 Inertia Tensor ............................................................................................................................................. 21

A.2 Space System Specific Mass Definitions ........................................................................................................ 22

A.3 Hardware Categories ...................................................................................................................................... 24

Annex B Functional Breakdown of Mass (Informative) ......................................................................................... 25

Figures

Figure 1 — General Mass Definitions ............................................................................................................................ 7

Figure 2 — Example of Mass Properties Control Process ............................................................................................. 9

Figure 3 — Example Plot of Mass versus Time .......................................................................................................... 11

Figure A.1 — Space Vehicle Mass Definitions ............................................................................................................. 22

Figure A.2 — Launch Vehicle Mass Definitions ........................................................................................................... 23

Tables

Table 1 — Mass Growth Allowance by Design Maturity .............................................................................................. 11

Table 2 — Mass Risk Assessment Example ............................................................................................................... 13

Table A.1 — Hardware Category Descriptions ........................................................................................................... 24


iv

Table B.1 — Example Functional Breakdown (Satellite) ............................................................................................. 25

Table B.2 — Example Functional Breakdown (Liquid Propulsion Stage) .................................................................... 26

Table B.3 — Example Functional Breakdown (Launch/Ballistic Vehicles) .................................................................. 26

Table B.4 — Example Functional Breakdown (Manned Reentry Vehicles) ................................................................. 27


v

Foreword This revision of the Mass Properties Control for Space Systems Standard was developed in response to

contractors who noted that there were implicit requirements called out in AIAA S-120-2006 (denoted by the

use of the word “shall”) that were not true requirements, thus adding unnecessary costs to contracts. In

response, a Mass Properties Engineering (MPE) Committee on Standards (CoS) was formed and voted

unanimously to revise the existing standard.

The International Society of Allied Weight Engineers, Inc., (SAWE), a major source of MPE Subject Matter

Experts, signed a Memorandum of Understanding to jointly develop both a revised standard and a revised

recommended practice with the American Institute of Aeronautics and Astronautics (AIAA) CoS.

The new revisions, designated as AIAA S-120A-2015 and SAWE RP A-3, are intended to fully replace AIAA

S-120-2006 and SAWE RP-11C.

This standard is intended to convey the minimally acceptable mass properties requirements for space

systems, while the associated SAWE RP A-3, Mass Properties Control for Space Systems, provides

guidance for implementation of a program-specific mass properties control plan. Together, the two

documents may also be used to establish requirements during preparation of acquisition contracts and

program-specific documents.

This standard contains proven methods and lessons learned for effective mass properties control, combines

tools necessary for timely evaluation of program mass properties, and enables early decision making

regarding possible design changes.

The primary objective of this standard is to provide an effective means for meeting program requirements

for space system mass properties control, analysis, verification, data management, and documentation. It

is intended to be comprehensive and practical and will be periodically updated to incorporate advances and

innovations.

At the time of approval, the members of the AIAA Mass Properties Engineering Committee on Standards were:

Geoffrey Beech, Chair National Aeronautics and Space Administration

(NASA) Marshall Space Flight Center

Mark Andraschko NASA Langley Research Center (LaRC)

Jeffrey Bautista Northrop Grumman

Jeffrey Cerro NASA LaRC

William Griffiths The Aerospace Corporation

Jennifer Herron Action Engineering

Roland Holzmann The Boeing Company

Robert Hundl Fluor

Bell Lee Raytheon

Daniel Kwon Orbital Sciences Corporation

Roland Martinez NASA Johnson Space Center (JSC)

John Nakai The Aerospace Corporation

Clinton Plaisted A.I. Solutions


vi

Glen Richbourg Lockheed Martin Space Systems

Company

Ricardo Roy United Launch Alliance

Robert Shishko Jet Propulsion Laboratory

Paul Weitekamp SpaceX

David Wolfe Blue Origin

Robert Zimmerman Retired

The above consensus body approved this document in Month 2015.

The current members of the AIAA CoS wish to thank the following for their contributions to the initial release

of this document: Tom Ajluni, Kevin Bee, Geoffrey Beech, Roger Belt, Gerard Drewek, David Finkleman,

Michael Froehlich, William Griffiths, Mahantesh Hiremath, Gary Holloway, Roland Holzmann, Quang Lam,

Bell Lee, Dean Liensdorf, Ian MacNeil, Thomas McGovern, John Nakai, Geoffrey Reber, Glen Richbourg,

Ricardo Roy, Ronald Solomon, Richard Sugiyama, Joseph Vecera, Ernest Wade, Louis Yang, and Robert

Zimmerman.

The AIAA Standards Executive Council (Mr. Amr ElSawy, Chairman) accepted the document for publication

in Month 2015.

The AIAA Standards Procedures dictate that all approved Standards, Recommended Practices, and

Guides are advisory only. Their use by anyone engaged in industry or trade is entirely voluntary. There is

no agreement to adhere to any AIAA standards publication and no commitment to conform to or be guided

by standards reports. In formulating, revising, and approving standards publications, the committees on

standards will not consider patents that may apply to the subject matter. Prospective users of the

publications are responsible for protecting themselves against liability for infringement of patents or

copyright or both.

Annexes A and B in this document are informative.


1

1 Scope This standard defines terminology and establishes uniform processes, procedures, and methods for the

management, control, monitoring, determination, verification, and documentation of mass properties during

the design, development, and operational phases of space systems, including their components and

subsystems. This standard applies to space vehicles (SVs), upper stage vehicles, injection stages, satellite

payloads, reentry vehicles, launch vehicles (LVs), and ballistic vehicles. This standard defines a minimum

set of mass properties requirements and is intended for use in developing a project-specific, contractually

required mass properties control plan (MPCP). When used in conjunction with the International Society of

Allied Weight Engineers, Inc., (SAWE) Recommended Practice RP A-3, the two documents serve as a

comprehensive reference for requirements and best practices in the field of space systems mass properties.

2 Tailoring When viewed from the perspective of a specific program or project context, the requirements defined in this

standard may be tailored in a program-specific MPCP. The requirements of this standard are presented as

a minimum set, and any changes or removal should be undertaken in consultation with the procuring

authority and subject matter experts where applicable.

NOTE Tailoring is a process by which individual requirements or specifications, standards, and related documents are

evaluated and made applicable to a specific program or project by selection, and in some exceptional cases,

modification and addition of requirements in the standards.

3 Applicable Documents The following documents contain provisions which, through reference in this text, constitute provisions of

this standard. For dated references, subsequent amendments to, or revisions of, any of these publications

do not apply. However, parties to agreements based on this standard are encouraged to investigate the

possibility of applying the most recent editions of the documents indicated below. For undated references,

the latest edition of the document referred to applies.

SAWE RP A-3 Mass Properties Control for Space Systems

SAWE RP 6 Standard Coordinate Systems for Reporting the Mass Properties of Flight

Vehicles

SAWE RP 16 Measurement of Missile and Spacecraft Mass Properties

4 Vocabulary 4.1 Acronyms and Abbreviated Terms

& Ampersand (and)

= Equal

≤ Equal to or less than

> Greater than

< Less than

- Minus

% Percent

+ Plus


2

3D Three dimensional

AIAA American Institute of Aeronautics and Astronautics

ANSI American National Standards Institute

ATP Authorization to Proceed

CAD Computer-Aided Design

CCB Change Control Board

CDR Critical Design Review

CDRL Contract Data Requirements List

CFE Customer-Furnished Equipment

CM Center of Mass

CoS Committee on Standards

ECLSS Environmental Control and Life Support System

EIDP End Item Data Package

FBS Functional Breakdown Structure

GSE Ground Support Equipment

H High (probability of occurrence)

ID Identify

IPT Integrated Product Team

ISO International Organization for Standardization

JSC Johnson Space Center

kg Kilogram

L Low (probability of occurrence)

LaRC Langley Research Center

LV Launch Vehicle

M Medium (probability of occurrence)

MGA Mass Growth Allowance

MIL-HDBK Military Handbook

MIL-STD Military Standard

MOI Moment(s) of Inertia

MP Mass Properties

MPE Mass Properties Engineer, Mass Properties Engineering

MPCB Mass Properties Control Board


3

MPCP Mass Properties Control Plan

NASA National Aeronautics and Space Administration

NTE Not to Exceed

PDR Preliminary Design Review

POI Product(s) of Inertia

PSRR Pre-shipment Readiness Review

RP Recommended Practice

SAWE International Society of Allied Weight Engineers, Inc.

SV Space Vehicle

SWI Standard Work Instruction

TP Test Procedure

TPM Technical Performance Measurement

VDL Variance Discrepancy Log

WBS Work Breakdown Structure

4.2 Terms and Definitions For the purposes of this document, the following terms and definitions apply. Annex A provides

mathematical representations of a number of the terms defined below as well as vehicle-specific graphical

summaries of the relationships between key definitions.

Actual Mass Properties mass properties determined by measurement or by comparison of nearly identical components, for which

measured mass properties are available (assessed as maturity category A5 or A6 in Table 1)

Allowable Mass the limit against which mass margins are calculated

NOTE 1 The allowable mass is a derived requirement set early in the program and is intended to remain constant until

there is a change in requirements.

NOTE 2 Examples of an allowable mass include a contractor not-to-exceed (NTE) mass limit or an informal mass

allocation to a design organization.

Basic Mass the current mass of dry or inert hardware based on an assessment of the most recent baseline design

NOTE 1 The design assessment includes the estimated, calculated, or measured (or actual) mass and includes an

estimate for undefined design details like cables, multi-layer insulation, and adhesives.

NOTE 2 The mass growth allowances (MGA) and uncertainties are not included in the basic mass.

Bulk Item a constituent of an assembly or part that is not readily identified by an exact quantity or graphical

representation and where its shape, volume, and mass may be determined upon installation or by a note

only. These items generally have a quantity of “as required” in the parts list, e.g., paints, structural

adhesives, fluids, tapes.


4

Bus the portion of an SV that supports payloads and performs functions related to the SV’s basic operation and

maintenance, such as flight control, power, and propulsion

Calculated Mass Properties mass properties determined from preliminary or released drawings or controlled computer models

(assessed as maturity category C3 or C4 in Table 1)

Center of Mass (CM) the point at which the distributed mass of a simple or composite body can be acted upon by a linear force

without inducing any rotation of the body

Critical Mass Properties

those mass properties that have limits that would jeopardize mission performance or safety if exceeded

Estimated Mass Properties

mass properties determined from preliminary data, such as sketches, analysis from preliminary layouts or

models, or parametric data (assessed as maturity category E1 or E2 in Table 1)

Forecast Mass predicted mass plus consideration for pending and potential mass changes

In-Scope Changes design modifications implemented by the contractor to meet contractual requirements

Launch Vehicle

a space system whose purpose is to carry one or more payloads from the surface of Earth (or other celestial

body) and deliver the payload(s) into space with position and velocity meeting desired target state vectors

at the desired time.

Mass

the measure of the quantity of matter in a body that results in the body’s resistance to change in translational

velocity

Mass Growth Allowance

the predicted change to the basic mass of an item based on an assessment of the hardware category,

design maturity, fabrication status, and an estimate of the in-scope design changes that may still occur

throughout life-cycle

NOTE 1 MGA should be defined as part of contract negotiations.

NOTE 2 The alternate word “contingency” is vague and is no longer used to define MGA or margin.

Mass Limit maximum mass that can satisfy all mission performance requirements

NOTE Also referred to as mission limit

Mass Margin the difference between the space system allowable mass and the predicted mass

Mass Properties mass, CM, moments of inertia (MOI), and products of inertia (POI)

Mass Properties Control Board (MPCB) a body tasked with reviewing and managing a space system’s mass properties, typically to produce a minimum mass design consistent with mission requirements and to identify risks to the overall program resulting from any non-compliance with mass properties requirements


5

Mass Properties Database a data management system used to record and manage the mass properties data records of a space system and its constituent parts Mass Reserve mass allowance defined and retained by the customer or program management for potential out-of-scope

changes or any other unforeseen mass impacts

Moment of Inertia a body's resistance to change in angular velocity about a defined axis resulting from the body's distribution

of mass

Out-of-Scope Changes design modifications that are not consistent with the current contract requirements

Overages non-flight items on a test article when a measurement is conducted

Payload for SVs, a mission-related subsystem (or subsystems) that performs a function or functions not directly

related to a space system's basic operation or maintenance; for LVs, the SV or system, LV adapter, and

other mission-unique hardware

Payload Margin for LVs, the difference between the predicted payload capability and the required payload capability to a

specified target state vector in terms of mass

NOTE Payload partial derivatives describe the relationship between payload margin and mass margin for hardware

jettisoned prior to achieving the target state vector corresponding to a particular mission trajectory design

Payload Partial Derivative for LVs, the rate of change in payload mass delivered to a specified target state vector divided by the rate

of change in mass (or other system parameter) of the specified LV component, valid within small variations

NOTE The payload partial derivative is 1.0 for LV hardware that arrives at the specified target state vector with the

payload.

Pending Change mass properties data that have been approved for incorporation into the database but, because of timing,

have not yet been incorporated

Potential Change an unapproved design modification that, if approved, would effect a change to the system mass properties

NOTE Changes that increase mass are called threats, and those that decrease mass are called opportunities.

Predicted Mass sum of the basic mass and the MGA; intended to estimate the final mass at system delivery or operation

NOTE CM, MOI, and POI values are derived using the predicted mass.

Predicted Payload Capability the analytically derived performance of a launch vehicle, expressed as payload mass to a target state

vector, based on launch vehicle predicted mass, launch site, trajectory, propellant loading, and

environmental conditions

NOTE LVs may relate changes in payload margin to changes in launch vehicle segment dry mass or propellant using

payload partial derivatives.


6

Product of Inertia a measure of a body's mass distribution asymmetry with respect to a reference coordinate system

Propellant Margin for LVs, the mass of usable main impulse propellant that the upper stage carries that is in excess of the

propellant needed to meet all performance and flight uncertainty reserve requirements for a specified

mission

NOTE 1 LV programs commonly express predicted performance risk for a specific mission in terms of propellant margin.

NOTE 2 LV programs may utilize propellant margin partial derivatives to evaluate the effects of changes in launch

vehicle segment predicted mass on propellant margin and mission performance.

Satellite an SV whose purpose is to navigate and operate in orbit around Earth or other celestial body Shortages flight items missing from a test article when a measurement is conducted

Spacecraft an SV

Space System a system designed to function in space, including crewed and unmanned SVs, in-space propulsion vehicles,

injection and upper-stage vehicles, satellite payloads, reentry vehicles, LVs, ballistic vehicles, and

components thereof

NOTE For the purposes of this document, space systems do not include Ground Support Equipment (GSE).

Space Vehicle a space system whose purpose is to navigate and operate in space, performing one or multiple functions,

which may include data collection; communications; research; delivery of cargo, equipment, personnel, or

weapons to or from space; reentry; or other purposes State Vector in astrodynamics or celestial dynamics, a combination of a vehicle’s position vector and velocity vector at

a specified date and time (epoch), uniquely determining the orbital parameter and/or trajectory of a vehicle

or other body in space.

Tare non-flight hardware, excluding overages, used to perform a measurement of a test article

Target State Vector for LVs, the desired vehicle state vector to be achieved when the payload is released from the LV. For

multiple payload missions, there will be multiple target state vectors.

Uncertainty plus or minus variation in predicted mass properties because of lack of definition, manufacturing variations

and tolerances, environment effects, or accuracy limitation of measuring devices or techniques

NOTE Uncertainty is calculated relative to predicted mass.

Figure 1 provides a graphical summary of the relationships between key definitions. (See also Figures A1 and

A2 in Annex A.)


7

Figure 1 — General Mass Definitions

5 Requirements 5.1 Mass Properties Control Mass properties control is the management of a system’s mass properties to enable the system to fulfill its

contractual and performance objectives. In most cases, a space system and its subsystems will have

explicit, contractually defined mass properties limits. In addition, other system performance requirements

frequently flow down to define internally derived mass properties requirements and limits.

Specifying appropriate mass properties requirements and implementing phase-appropriate control

processes from conceptual development through production and operations are of critical importance for a

successful space system development. This standard describes the fundamental elements of mass

properties monitoring, management, and control to be implemented by the space system contractor. These

fundamental elements may be further augmented and clarified by additional contractually levied

requirements, standards, and recommended practices.

Allowable Mass

Predicted Mass

Basic Mass

Mass Margin

Mass Limit or Mission Limit

Mass Reserve

Mass Growth Allowance (MGA)

Mass Margin

Mass Limit or Mission Limit

Mass Reserve



8

5.1.1 Scope

The mass properties control program for a space system is used to determine, control, and document the

mass properties of the space system, including subsystems and components. The mass properties control

program includes all subcontractor items, associate contractor items, and Customer-Furnished Equipment

(CFE) items.

System mass properties control includes the mass properties analyses, verification, record management,

and management processes supporting performance, stability and control, structural design, structural

loads and dynamics analyses, and simulations of flight and other dynamic events. Mass properties are also

determined for the purpose of supporting project management and risk assessment.

5.1.2 Mass Properties Control Plan

The contractor shall develop and document an MPCP for the space system to state the management plan

and the procedures for mass properties control and verification during the various program phases. The

objective of the plan is to formulate an organized mass properties control program to meet the space

system’s critical mass properties requirements. The MPCP is subject to review and approval by the

customer or customer representative.

5.1.2.1 Subcontractor Mass Properties Control Plan

The contractor shall be responsible for the mass properties control of each subcontractor and supplier.

Each procurement document includes a mass properties control section to impose the applicable and

appropriate requirements of this document on the subcontractor or supplier.

NOTE Mass properties control may be tailored as appropriate for items with measured or well-defined mass properties.

5.1.2.2 Supplier Interface

The contractor shall structure its subcontracts to ensure suppliers provide sufficient information to support

timely integration of subunit mass properties into complete unit mass properties and to ensure timely

responses to information requests. The procuring authority is responsible for providing sufficient and timely

CFE item mass properties information to the contractor.

5.1.3 Mass Properties Control Process

The mass properties control process is initiated in the pre-proposal or conceptual design phases, where an

initial mass budget is determined, based on a clear understanding of the mass properties requirements and

an estimate of predicted mass properties to assess compliance to requirements. The contractor shall

develop achievable mass properties objectives and assist the procuring authority in specifying general

system mass properties requirements and their proper allocation to the configuration element requirements.

Figure 2 shows an example of the mass properties control process. Additional components of the control

process may include technical performance assessment, a mass reduction plan, MPCB, mass allocation

and trend analysis, or mass properties monitoring.


9

Figure 2 — Example of Mass Properties Control Process


10

5.1.4 Requirements Flowdown and Traceability

The contractor shall show traceability to its source for all system and subsystem mass properties

requirements, including, but not limited to, contractual, attitude control, and mission and ground handling

requirements.

5.1.5 Mass Maturity Assessment

The contractor shall perform a mass maturity assessment for each record in the mass properties database

by reviewing the heritage of the component (new, modified, or existing), the stage of the design (layout,

preliminary, released) and the method by which the data were derived (estimate, computer-aided design

(CAD) analysis, measurement).

5.1.6 Assessment of Predicted Mass Properties against Requirements

Mass maturity is a strong indicator of the maturity of the design according to the application of MGA and

programmatic development milestones. The contractor shall maintain the percentage of aggregate

predicted mass in each maturity category in Table 1 and perform an analysis to show predicted performance

and acceptable margins for each identified critical mass properties requirement. Program-specific

thresholds are established in advance. The mass properties used for comparison against requirements are

the predicted mass properties (basic mass properties plus mass and inertia effects of MGA).

5.1.7 Mass Growth Allowance

The contractor shall include in the mass data an allowance for the expected mass growth resulting from

lack of maturity in the current design data according to Table 1. Mass growth varies as a function of

hardware and its design maturity. The MGA is applied at the lowest design detail level reported in the mass

properties database. Depletion of the MGA follows the design process; as the design and analyses of the

hardware matures, the MGA depletes to reflect increased confidence in the predicted final mass. The

ranges of values in Table 1 are meant to be applied as follows: lower percentages of MGA are applied for

a follow-on or block change vehicle by the same contractor; mid-range values are applied for a new payload

on an existing or modified vehicle; and higher values are used for a new system for which the contractor

does not have demonstrated experience.

If required by the customer, LV provider, or the contractor’s attitude control system analysis, compliance

to requirements should include both the plus and minus mass properties uncertainties applied to the

predicted mass properties.


11

Table 1 — Mass Growth Allowance by Design Maturity

Maturity Code

Design Maturity

(Basis for Mass Determination)

Percentage Mass Growth Allowance

Electrical/Electronic Components

Str

uctu

re

Th

erm

al C

ontr

ol

Pro

pu

lsio

n

Ba

tte

rie

s

Wir

e H

arn

esse

s

So

lar

Arr

ay

EC

LS

S,

Cre

w

Syste

ms

Bra

cke

ts, C

lips

an

d H

ard

wa

re

Me

ch

an

ism

s

Instr

um

en

tatio

n

0-5 kg 5-15 kg >15 kg

E

1 Estimated 20-35 15-25 10-20 18-25 30-50 15-25 20-25 50-100 20-35 20-30 20-35 18-25 25-75

2 Layout 15-30 10-20 5-15 10-20 15-30 10-20 10-20 15-45 10-20 10-20 10-25 10-20 20-30

C

3 Preliminary Design 8-20 3-15 3-12 4-15 8-15 5-15 5-15 10-25 5-15 5-15 8-15 5-15 10-25

4 Released Design 5-10 2-10 2-10 2-6 3-8 2-7 3-7 3-10 3-5 3-8 3-8 3-4 3-5

A

5 Existing Hardware 1-5 1-3 1-3 1-3 1-3 1-3 1-3 1-5 1-3 1-4 1-5 1-3 1-3

6 Actual Mass Measured mass of specific flight hardware; no MGA; use appropriate measurement uncertainty.

S 7 CFE or Specification Value Typically, an NTE value is provided, and no MGA is applied.

Expanded Definitions of Maturity Categories

E1 Estimated a. An approximation based on rough sketches, parametric analysis, or incomplete requirements b. A guess based on experience c. A value with unknown basis or pedigree

E2 Layout a. A calculation or approximation based on conceptual designs (equivalent to layout drawings or models) prior to initial sizing b. Major modifications to existing hardware

C3 Preliminary Design a. Calculations based on new design after initial sizing but prior to final structural, thermal or manufacturing analysis b. Minor modification of existing hardware

C4 Released Design a. Calculations based on a design after final signoff and release for procurement or production b. Very minor modification of existing hardware

A5 Existing Hardware

a. Measured mass from another program, assuming that hardware will satisfy the requirements of the current program with no changes b. Values substituted based on empirical production variation of same or similar hardware or measured mass of qualification hardware c. Catalog values

NOTE: The MGA percentage ranges in the above table are applied to the basic mass to arrive at the predicted mass.


12

5.1.8 Mass Threats, Opportunities, and Probability of Occurrence

The assessment of mass properties predicted performance also forecasts the effect of potential changes

to the design that may adversely impact predicted mass properties margin against requirements. The

contractor shall evaluate and maintain a list of all potential design changes with threats to increase and

opportunities to decrease the system mass. Each potential change is evaluated and assigned a percent

probability of occurrence, for example: High (H) (above 75 percent), Medium (M) (between 75 and 25

percent), or Low (L) (less than 25 percent). For each opportunity to save mass, estimated costs should be

included.

5.1.9 Mass Margin

Mass margin is meant to mitigate potential mass increases from omissions or refinement of existing design

requirements that exceed MGA allocations. Acceptable levels of mass margin vary, depending on the

complexity and the design heritage (new, modified, production) of the space system and the risk that the

procuring authority and contractor are willing to accept. Table 2 shows an example of margin thresholds

phased through development milestone.

Mass margin is the difference between the allowable mass and the predicted mass. If the high-side

manufacturing variation (maturity category A5, item b) is not included in the predicted mass, the contractor

explicitly accounts for this uncertainty in margin calculations. For LVs, the contractor shall correlate LV

payload margin to mass margin of all stages and to other hardware under development.

5.1.10 Mass Risk Assessment

In general, space system mass margin is expressed as the allowable mass less the predicted mass. When

developing the mass margin percent, mass margin is divided by the basic mass.

Table 2 presents an example of a mass risk assessment of the percentage MGA, percentage mass margin,

and sum of these by program phase. The MGA is derived in Table 1, and is shown for reference in this

table. The sum of the MGA and dry mass margin, however, is historically based, and deviations from this

baseline are allowed if there is justification, e.g., extensive use of off-the-shelf hardware would significantly

lower MGA in the early phases of a program. The contractor shall monitor mass risk according to predefined

criteria for margin and MGA throughout the program

Color code definitions in Table 2:

Green: At each specific design phase, if MGA and margins are greater than the percentages shown in

the green shaded areas of Table 2, mass risks are considered to be minimal. No action is required

other than monitoring the mass status.

Yellow: If MGA and margins are in the yellow percentage ranges, there is medium mass risk. A risk

mitigation plan is prepared that pays particular attention to potential design changes that would

remediate the margin.

Red: If MGA and margin percentages are in the red shaded area, there is high mass risk, and an immediate mass audit, mass reduction effort, or risk mitigation process is initiated.


13

Table 2 — Mass Risk Assessment Example

Program Milestone

Recommended MGA

Recommended Mass Margin MGA + Mass Margin

(%)1 (%)1 (%)2 Grade

ATP

>15 >15 >30 Green

9<MGA≤15 10<Mass Margin≤15 19<MGA + Mass Margin≤30 Yellow

≤9 ≤10 ≤19 Red

PDR

>12 >9 >21 Green


≤8 ≤5 ≤13 Red

CDR

>7 >5 >12 Green


≤4 ≤3 ≤7 Red

Released Design

>3 >2 >5 Green


≤2 ≤1 ≤3 Red

Final 0 >1 >1 Green 1. The percentages of MGA and Mass Margin in the above chart are defined as follows:

MGA = Predicted Mass Basic Mass % MGA = (MGA/Basic Mass) × 100 % Mass Margin = [(Allowable Mass - Predicted Mass)/Basic Mass] × 100 2. The % (MGA + Mass Margin) is defined as:

% MGA + Mass Margin = [(Allowable Mass Basic Mass)/Basic Mass] × 100

5.1.11 Technical Performance Measurement (TPM)

The contractor shall track and status all critical mass properties (including mass, CM, MOI, and POI) using

TPM charts that show basic and predicted performance against derived limits and contractual requirements.

Throughout the contract period, the contractor determines and documents the mass properties limits for

each critical requirement. These control limits are applied to the appropriate TPM charts to show predicted

performance margin against the requirement.

5.1.12 Mass Properties Control Board

If program specific margins are not acceptable, the program shall institute a MPCB. The MPCB or an

existing Change Control Board (CCB) assumes the responsibility for effecting a minimum mass design

consistent with mission requirements and for identifying risks to the program for any non-compliance to

mass properties requirements. The MPCB sets internal mass properties allocations at the subsystem and

unit level to meet system-level mass properties requirements. Subsystem and unit mass limits should be

monitored and adjusted as necessary to maintain system margin. Key functions of the MPCB are explained

in SAWE RP A-3.

An idealized graphical representation of basic mass, MGA, predicted mass, and margin versus time is

depicted in Figure 3.


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Figure 3 — Example Plot of Mass versus Time

5.2 Analysis 5.2.1 Scope

Mass properties analysis follows the methodology defined in this section and in a program-specific MPCP

and provides direct input to the various reports. The contractor shall perform mass properties analysis to

support the program requirements for space system mass properties accuracy and documentation for all

configurations throughout the program. The contractor assesses the scope of the mass properties analyses

required and implements a plan to satisfy compliance with all of the program mass properties requirements.

The contractor maintains analysis documentation to substantiate the accuracy and completeness of the

space system mass properties database throughout program phases from proposal to launch and

operation.

5.2.2 Methods of Analysis

The primary methods of analysis are typically dictated by the program phase. During all program phases,

from proposal to launch and operation, the contractor shall substantiate the mass properties database and

MGA values by providing a maturity assessment of each subsystem and key component and document

associated coordinate systems.

If heritage hardware is used, the contractor shall define the pedigree for each space system detail using

the categories provided in Table 1.

If scaling techniques are used, the contractor shall provide a basis of estimate to support these methods.


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5.2.2.1 Manual Layout/Drawing Analysis

If a manual layout/drawing analysis approach is used in estimating mass properties, the contractor shall

document and maintain records of the manual calculation of mass properties data.

5.2.2.2 Three-Dimensional (3D) Model Analysis

If a 3D model analysis is used, all constituents of the parts and assemblies shall be accounted. Those

constituents not typically modeled in 3D computer-aided design (CAD) software, such as bulk items and

fasteners, should be assessed to determine their mass properties.

5.2.3 Flight Hardware Analysis

All new or modified components or units shall be analyzed to a level of detail commensurate with the impact

to the system mass properties requirements. The contractor’s mass properties personnel verify that the

space system mass properties analysis is accurate and complete, including that of the subcontractors and

contributing teammates. All test instrumentation or GSE that remains with the space system through launch

or operation is controlled as flight hardware and is included in the mass properties database.

5.2.4 Mass Properties Uncertainty Analysis

Uncertainties originate from several sources, including estimates, calculations from models, and

measurements. There are inherent uncertainties in all mass properties parameters. If required for a specific

program, the uncertainty of the space system’s mass properties shall be analyzed at major milestones in

the program. The level of detail of the analysis is commensurate with the criticality of the parameter

involved, e.g., deployable reflectors or solar arrays require attention to full mass properties deviations,

whereas system-level uncertainties focus mainly on mass. An evaluation of margins determines the

necessity of performing a detailed uncertainties analysis.

5.2.5 Special Analyses

Specific mass properties analyses may be requested by internal customers, such as structural analysis,

dynamics, attitude control, mission engineering, ground support and transportation operations, or payload

layout design. Additional special analyses not detailed in the following paragraphs include Finite Element

Model Mass Distribution, Mission Worst Case, Post-flight, Breakup/Disposal, Anomaly Investigation, and

Ground Operations. A description of these analyses can be found in SAWE RP A-3.

5.2.5.1 Balance and Ballast Mass Analysis

For programs where CM, static or dynamic balance, or MOI requirements are critical, and balance or ballast

mass is required to meet those requirements, the contractor shall analyze the optimum locations and

configuration of the balance and ballast mass required. Equipment layout trades are performed to minimize

the total amount of balance or ballast mass required. A structural analysis is performed to define the

maximum amount of mass allowed at each balance or ballast mass location.

5.2.5.2 Mission and Attitude Control Systems Analysis

Mass properties analysis in support of space system launch and on-orbit operations shall be performed.

The analysis includes determination of propellant location, mass properties of movable objects in the

stowed and deployed configurations, and sequential mass properties of the space system configuration

from launch to on-orbit operations to de-orbit.

5.2.5.2.1 Propellant

The contractor shall calculate the propellant mass properties based on the system predicted dry mass. The

associated mass for pressurizing gases, loading uncertainties, operational uncertainties, residuals, and

other inerts should also be calculated. MGA is not applied to propellant mass calculations; rather, propellant

reserves and uncertainties are included in a separate propellant analysis.


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5.2.5.2.2 Movable Objects

The mass properties of movable objects, e.g., rotating appendages, shall be determined for their nominal

stowed and deployed conditions, as well as any intermediate positions that may be critical because of

stability, control, or mission success concerns. The pivot point locations (if applicable) are documented with

a coordinate system located relative to the space system coordinate system for each movable object. The

sequence of rotations and translations of the movable object is documented.

For LVs, mass properties shall be calculated for movable portions of engine or nozzle hardware and for

any jettisoned or separated hardware.

5.2.5.2.3 Mission Sequential Mass Properties

The contractor shall perform sequential mass properties as necessary to support guidance navigation and

control, jettison, and re-contact analyses. An analysis should be performed to determine if propellant

sloshing has a significant impact on system mass properties. The space system mass properties are

determined and documented as a function of time or propellant fraction fill from mission initiation through

mission completion.

5.3 Verification 5.3.1 Verification Plan

The contractor shall develop and document a verification plan to describe and substantiate the methods

used to verify that mass properties requirements are met.

5.3.1.1 Verification Criteria

The contractor defines the verification criteria based on flow-down requirements to:

Identify critical mass properties parameters requiring verification: mass, CM, MOI, or POI.

Describe the accuracies required for above parameters to comply with requirements. Select verification methods that will meet the mass properties requirements.

5.3.1.2 Verification Method Selection

Verification may be accomplished by analytical methods, by measurement, or by a combination of both.

The selection of the verification methods is justified by an approved verification plan (Verification Cross

Reference Matrix or similar).

5.3.2 Test Plan

The test plan, either as part of the verification plan or as a separate subordinate document to the verification

plan, documents the mass properties to be verified by measurement. (See SAWE RP 16 and SAWE RP A-

3 for guidelines on mass properties measurements.) The test plan shall include the test description, test

equipment to be used and measurement accuracies, figures or photos of test setups, expected results

versus requirements, GSE requirements, standard work instruction (SWI) if applicable, and a test procedure

(TP) outline or reference to an existing TP. If the determination of flight mass properties from test data

requires adjustments for buoyancy in air or local gravity variations, the test plan shall also describe the

measurements and computation techniques to be applied.

5.3.2.1 Test Description

The test description includes a list of the test items, verifies the test configuration, identifies the mass

properties parameters to be measured, states the test accuracy requirements, identifies the test equipment,

and establishes the test setup.


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5.3.2.2 Ground Support Equipment

The test plan identifies whether existing or new GSE is required for unit-, subsystem-, or system-level

measurements. New design requirements are communicated to the appropriate design organization. A test

equipment fit check shall be performed on all new GSE, allowing adequate time for problem resolution so

as not to impact the test schedule. If GSE is attached to the unit being measured during the mass properties

measurement, the test plan shall identify how the mass properties of the GSE will be measured and tracked.

5.3.2.3 Measurement Uncertainty

The test plan should include a preliminary uncertainty analysis based on measurement system accuracies,

configuration differences from flight, alignment accuracy, assessment of potential error in methods used to

reconcile overages and shortages, and other identifiable uncertainties. The purpose of this initial

uncertainties analysis is to validate that the proposed measurement plan will meet mass properties

verification accuracy requirements with adequate margin.

5.3.2.4 Measurement Schedule

The test plan provides a measurement schedule based on the program master phase plan and updates the

schedule at major milestones. The schedule is transmitted to the customer, who reserves the right to

witness critical measurements.

5.3.3 Standard Work Instruction

The SWI shall be documented and included in the test plan, where applicable, to address the standard

practice and general procedure for mass properties measurements. SWIs used during system-level testing

should be referenced in the test procedure.

5.3.4 Test Procedure

The TP is an important part of the test plan when measurements are required for space system-level mass

properties, e.g., mass, CM, MOI measurements, and static or dynamic balance. Mass properties tests shall

be conducted in accordance with approved and released detailed test procedures, subject to review and

approval by the customer or customer representative, the content of which is described in the following

subsections.

5.3.4.1 Test Scope

The test scope describes the general plan for the test objective, success criteria, test methods, and

operation.

5.3.4.2 Applicable Documents, Equipment, GSE, and Software

The test procedure lists all applicable documents related to the test, including government documents,

standards, specifications, a list of the associated equipment, GSE and software, related SWI, general

practices, and procedures.

5.3.4.3 Requirements

The following should be included in the mass properties test procedure: environmental conditions, security

level, test equipment data, safety provisions, data log, document references, and success criteria.

5.3.4.4 Test Configuration

The mass properties test configuration and environment shall be accurately documented in detail. Any

change during the test is recorded and evaluated to validate that the test objectives and requirements are

met. Any configuration change after the test shall be monitored, recorded, and assessed for impact on

requirements to assure the mission success. Refer to SAWE RP 16 and SAWE RP A-3 for detailed

guidance.


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5.3.4.5 Test Sequence

The test procedure shall include a detailed step-by-step sequence to be followed. All changes from the sequence are authorized and recorded by the responsible Mass Properties Engineering (MPE) test director. The Quality Assurance engineer should record the changes in a Variance Discrepancy Log (VDL) or similar document.

5.3.5 Data Record

Records for each major mass properties measurement performed in accordance with approved procedures or detailed work/process instructions shall be documented, and these documents are made available for review by the customer or customer representative upon request, including the subcategories listed below.

5.3.5.1 Records for Mass Properties Measurements

Records for mass properties measurements include the raw test data and the test data reduction methods used to derive the as-measured test results and the determination of the flight configuration mass properties. These data and methods are subject to review by the customer or customer representative.

5.3.5.2 Post-Test Configuration Change Log

A formal change log is maintained after final system-level mass properties testing to ensure that any changes affecting mass properties that occur between the final test and launch are accurately accounted, and that margins are maintained.

5.4 Mass Properties Data Management 5.4.1 Scope

The contractor’s mass properties data management system is an analysis model used to maintain the program baseline mass properties for analysis of all critical parameters and all phases of ground and flight operation.

5.4.2 Data Management System

The contractor shall develop and maintain a mass properties database of the space system with sufficient capability and accuracy to support program reporting requirements. The mass properties database reflects the most recent information from design data, drawings, CAD models, mass properties measurements, CFE data, associate contractors, subcontractors, and suppliers.

5.4.2.1 Database Requirements

The contractor’s mass properties database management system should provide the following:

Ability to store basic mass, MGA, and predicted and actual mass for each component of the space system.

Ability to perform standard mass properties calculations from parts, assemblies, installations to bus, payload, and space system levels with capability to sort and recalculate based on user selection of criteria, e.g., Functional Breakdown Structure (FBS) and Work Breakdown Structure (WBS).

Mass properties database formatting flexibility (sort capability).

Ability to calculate sequential mass properties.

Mass properties change tracking.


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For production programs, the capability to track more than one system configuration simultaneously.

5.4.2.2 Frequency of Database Update

The mass properties database is maintained up to date in support of contractually required mass properties TPMs and reporting.

5.4.3 Data Organization Utility

The mass properties database includes the flexibility to sort and report the mass properties data in multiple formats, based on criteria from programmatic and technical stakeholders, including WBS and FBS.

5.4.4 Database Record Keeping

The contractor shall maintain records that represent a snapshot in time of the detailed mass properties database in electronic format. At a minimum, released records that represent the mass properties data at Authorization to Proceed (ATP), Preliminary Design Review (PDR), Critical Design Review (CDR), Pre-shipment Readiness Review (PSRR), and launch shall be created and retained for the duration of the program.

5.5 Documentation 5.5.1 Scope

Mass properties documentation consists of plans and reports. Documentation requirements are levied in conjunction with the procurement authority in the Statement of Work and Contract Document Requirements List (CDRL) sections of the system specification. All documentation is subject to review and approval by the customer or customer representative. The required documentation specified by this standard includes those described in the following sections.

5.5.2 Mass Properties Control Plan

The contractor shall document an MPCP in accordance with section 5.1 in this document. The plan defines program-specific tailoring of this standard, including the following minimum requirements:

MGA maturity table with specific values replacing the ranges in Table 1.

Identification of the mass control authority and process for changing mass properties.

Identification of all critical parameters and associated requirements.

TPM format and submission frequency.

Mass properties reporting and submission frequency.

Summary verification strategy and reference to associated program verification documentation.

5.5.3 Verification Plan

The contractor shall document program-specific mass properties verification planning, as specified in section 5.3.1 of this standard, describing and substantiating the methods to be used to verify the program critical mass properties.

5.5.4 Mass Properties Test Plans and Procedures

The contractor shall develop formal test plans, procedures, and work/process instructions in accordance with sections 5.3.2, 5.3.4, and 5.3.5 of this standard. Test procedures document measurements of critical mass properties at the space system level. Detail work/process instructions document measurement of the mass or CM of a unit, part, or an assembly.


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5.5.5 Test Completion Reports

The contractor shall document data records specified in section 5.3.5 of this standard for each critical mass properties test, performed in accordance with approved verification planning and released procedures, in a test completion report. The report demonstrates that all associated mass properties requirements are met, or if not, that a recovery plan (such as adding balance mass) is in place.

5.5.6 Contract Change Proposals

The contractor shall document and substantiate the effect on vehicle mass properties resulting from proposed changes submitted with the change proposal.

5.5.7 Mass Properties Status Report

The contractor shall develop mass properties status reports that satisfy the needs of the customer, program office, and other internal customers who rely on the timely communication of mass properties information. The content of a status report varies with the complexity of the program. The common elements for a status report include a summary paragraph for management review, basic and predicted mass properties in as much detail as practicable, coordinate system reference, mass changes since last report, potential and pending mass changes, and margins.

6 Bibliography

[1] ISO 22010:2007E: Space systems – Mass properties control

[2] JSC-23303: Design Mass Properties, Guidance and Formats for Aerospace Vehicles, Dated March 1989

[3] Matthews, G. Weight Growth: A Process and Its Utility, SAWE Paper 2230. Dated 1984

[4] MIL-HDBK-1811: Department of Defense Handbook, Mass Properties Control for Space Systems,

Dated 12 August 1998

[5] Zimmerman, R.L., and Nakai, J.H. Are You Sure? — Uncertainty in Mass Properties Engineering, SAWE

Paper 3360. Dated 2005


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Annex A Supplemental Information for Terms and Definitions (Informative)

A.1 Mathematical Descriptions The following mathematical descriptions are provided to aid understanding of certain definitions contained in section 4.2.

A.1.1 Mass

Unlike weight, mass is an intrinsic property that is independent of the gravitational field. Mass is given by

m dm for a continuous system or

m mi for a discrete system.

A.1.2 Center of Mass

The CM in the X-axis is given by

Xcm ( xdm)

m for a continuous system or

xcm ( mi xi )

m for a discrete system relative to a defined, fixed coordinate system.

A.1.3 Moment of Inertia

MOI and POI together quantify the distribution of mass relative to a defined coordinate system. MOI are defined as the sum of the products of each element of mass by the square of the perpendicular distance

from a specified axis. For example, the moment of inertia about the X-axis is given by

Ixx (y 2 z 2 )dm

for a continuous system or

Ixx mi (y i2 z i

2 ) for a discrete system. Typically, MOI are defined with respect to the CM.

A.1.4 Product of Inertia

POI are defined as the sum of the product of each element of mass by the perpendicular distances from

two specified axes. For example, a positive integral product of inertia about the X and Y-axes is given by

Ixy xydm for a continuous system or

Ixy mi xi y i for a discrete system. Usually, POI are defined

with respect to the CM.

POI are often defined as the negative integral

(Ixy xy dm). Special attention should be paid to

understanding whether a positive or negative integral is used in the determination of the POI. POI is

expressed in the same units as MOI, but it can have either positive or negative polarity.

A.1.5 Inertia Tensor

An inertia tensor consists of MOI (diagonal terms) and POI (off diagonal terms) in the coordinate system of

interest. The eigensolution of the inertia tensor provides three principal inertias (eigenvalues) and their

corresponding principal axes (eigenvectors).

For a continuous system (with xyz coordinates):

I

2y 2z dm xydm xzdm

xydm 2x 2z dm yzdm

xzdm yzdm 2x 2y dm


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For a discrete system:

I

Ixxi

i

mi [(y i y )2 (z i z )2 ]i

Ixyi

i

mi (xii

x )(y i y ) Ixzi

i

mi (xii

x )(z i z )

Ixyi mi (xi

i

x )(y i y )i

Iyyi

i

mi [(xi x )2 (z i z )2 ] Iyzi

i

mi (y ii

y )(z i z )i

Ixzi

i

mi (xii

x )(z i z ) Iyzi

i

mi (y ii

y )(z i z ) Izzi

i

mi [(xi x )2 (y i y )2 ]i

If the coordinate axes of a body align with the principal axes of that body, then the inertia tensor is a diagonal

matrix, i.e., POI are zero.

The inertia tensor quantifies the effects of the distribution of mass of a body on the rotational dynamics of

that body. In theory, zero dynamic imbalance occurs when a rigid body spins about one of its three principal

axes; however, instability may occur when not spinning about the major principal axis or dealing with flexible

bodies.

A.2 Space System Specific Mass Definitions

Figure A.1 — Space vehicle mass definitions

Space Vehicle (SV) Allowable Wet Mass at Launch

Wet Mass Margin at Launch

SV Predicted Wet Mass at Launch

LV/SV Interface Adapter

(Including MGA and Mission-Peculiar Items)

SV Predicted Wet Mass

Predicted Propellant Mass

SV Predicted Dry Mass

MGA for Payload


MGA for Bus

SV Basic Dry Mass

Payload Basic Dry Mass

Basic Dry Mass

Bus Basic Dry Mass


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Figure A.2 — Launch vehicle mass definitions

NOTE Second and higher stages should use the same mass definitions as shown for the first stage.

Launch Vehicle Wet Mass

Common Adapter Predicted Mass

Second Stage Wet Mass

Interstage Predicted Mass

First Stage Wet Mass

First Stage Inert Mass

First Stage Unusable Propellant

First Stage Predicted Mass

First Stage MGA

First Stage Usable Propellant

First Stage Basic Mass


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A.3 Hardware Categories Table A.1 — Hardware Category Description

Table 1 Hardware Category

Description

Electrical/ Electronic

Components

Primary purpose is to manage electronic data or power

Any unit requiring electrical power except as reserved for other categories such as Battery, Solar Array, Thermal Control, Mechanisms, Propulsion, or Instrumentation

Includes but is not limited to: a chassis that houses the electronic components. This includes but is not limited to: communications, avionics, computers, and power conditioning, conversion or distribution

Structure

Primary purpose is to provide structural support for primary and secondary loads, and attachments

Includes but is not limited to: support panels, support tubes or trusses, doublers*, and adapters

Brackets, Clips, Hardware

Primary purpose is to provide support for bracketry, attach hardware, grounding tabs, support or clamps for cables, wiring, and propellant lines

Battery

Primary purpose is to provide stored electrical power

Includes but is not limited to various sorts of power cells

Units that support Power Conditioning should be under Electrical/Electronic Components

Solar Array Electrical device consisting of a collection (array) of connected solar (photovoltaic) cells

used for converting solar energy into electricity

Thermal Control

Primary purpose is to manage or control the temperature of the system

Includes but is not limited to: various louvers, heat pipes, blanketing, mirrors, thermal protection systems, thermal surface finishes, heaters, radiators, and phase changing materials

Mechanisms

Primary purpose is to provide mechanical linkage for the reorientation or repositioning of other devices, and mechanical devices that move

Includes but is not limited to: various deployment mechanisms, positioners, gimbals, bearing assemblies, and momentum or reaction wheels

Propulsion

Primary purpose is to provide axial or lateral thrust and/or attitude control to the system

Includes but is not limited to: propellant tanks (liquid and/or gas), thrusters (examples are chemical-liquid, chemical-solid; electric, nuclear), valves, manifolds, feed lines and fittings

Wire Harness

Primary purpose is to transmit signals or power to the rest of the system

Includes but is not limited to: flat or round conductive wiring, fiber optic lines, coaxial cabling, ordnance transfer lines

Instrumentation Primary purpose is to sense or measure the operating environment

Includes but is not limited to: thermocouples, strain gages, vibration transducers, accelerometers

ECLSS, Crew Systems

Primary purpose is to provide a habitable environment for a flight crew in a crew compartment of a manned space system in addition to cooling or heating various space systems or components

Typically consists of an air revitalization system, water coolant loop systems, atmosphere revitalization pressure control system, active thermal control system, supply water and waste water system, waste collection system and airlock support system

Crew systems include but are not limited to extra-vehicular activity equipment, health and safety equipment, laptops, and other support equipment

NOTE These category definitions are for the purpose of assigning an MGA and not intended to be used as subsystem definitions for a specific program.

*Doublers could be either categorized under Structure or Thermal Control; suggest categorizing by primary usage.


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Annex B Functional Breakdown of Mass (Informative) Table B.1 — Example Functional Breakdown (Satellite)

1. Payload 2. Structure 2.1 Basic Structure 2.1.1 Main Truss 2.1.2 Equipment, Bulkheads, and Platforms 2.1.3 Kick Motor Support Cone 2.2 Secondary Structure 2.2.1 Reaction Control System Tank Supports 2.2.2 Momentum Wheel Supports 2.2.3 Solar Array Retention Fittings 2.3 Adapter, Separation 2.4 Mechanical Integration (hardware, clips, misc.) 3. Thermal Control 3.1 Louvers 3.2 Heat Pipes 3.3 Insulation 3.4 Surface Mirrors, Paint 4. Electrical Power 4.1 Solar Array 4.1.1 Power Source 4.1.2 Substrate 4.1.3 Drives 4.2 Converters 4.3 Power Switches 4.4 Electrical Integration (harness, connectors, hardware, misc.) 5. Guidance, Navigation 6. Data Management 7. Telemetry, Tracking, Command 8. Orientation Control 9. Reaction Control 10. Propulsion 11. Fluids


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Table B.2 — Example Functional Breakdown (Liquid Propulsion Stage)

1. Structure 1.1 Fuel Tank 1.1.1 Domes 1.1.2 Cylinder 1.1.3 Skirts 1.1.4 Anti-slosh Devices 1.2 Oxidizer Tank 1.3 Intertank Structure 1.4 Thrust Structure 1.5 Launch Supports 2. Thermal Control 3. Main Propulsion 3.1 Rocket Engine 3.1.1 Thrust Chambers 3.1.2 Pumps 3.1.3 Engine Systems 3.2 Fuel Feed 3.3 Oxidizer Feed 3.4 Pressurization 3.5 Fill, Drain, Vent 4. Thrust Vector Control 5. Reaction Control System 6. Secondary Power 6.1 Electrical 6.2 Hydraulic 7. Avionics 7.1 Guidance, Navigation, and Control 7.2 Data Management 7.3 Telemetry, Tracking and Command 7.4 Command and Data Handling 8. Range Safety and Abort 9. Fluids 9.1 Impulse Propellant 9.2 Residual Propellant 9.3 Reserve Propellant 9.4 Bias Propellant 9.5 Outage Propellant 9.6 Pressurization Gas


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Table B.3 — Example Functional Breakdown (Launch/Ballistic Vehicles)

1. Stage I 1.1 Oxidizer tank 1.2 Intertank 1.3 Fuel Tank 1.4 Engine Section 1.5 Propulsion 1.6 Interstage 1.6.1 Primary Structure 1.6.1.1 Forward Rings 1.6.1.2 Aft Rings 1.6.1.3 Skin 1.6.1.4 Doors 1.6.1.5 Fasteners 1.6.2 Secondary Structure 1.6.3 Environmental Protection 1.6.4 Separation Systems 1.6.5 Electrical/Electronics System 2. Assist Motors 3. Stage II 4. Stage III 5. Payload Attach Fitting 6. Payload Fairing 7. Payload

Table B.4 — Example Functional Breakdown (Manned Reentry Vehicles)

1. Crew and Flight Crew Equipment 2. Environmental Control and Life Support Systems (ECLSS) 3. Structure 3.1 Primary Structure 3.2 Secondary Structure 3.3 Ingress/Egress Hatch 3.4 Service Module Adapter, Separation System 4. Thermal Control 4.1 Active Cooling 4.2 Insulation 4.3 Surface Mirrors, Paint 5. Thermal Protection System (for reentry) 6. Electrical Power 6.1 Batteries 6.2 Converters 6.3 Power Switches 6.4 Electrical Integration (harness, connectors, hardware, misc.) 7. Avionics 7.1 Guidance, Navigation, and Control 7.2 Data Management 7.3 Telemetry, Tracking, Command 7.4 Command and Data Handling 8. Recovery Systems 9. Seats 10. Landing Attenuation 11. Reaction Control System 12. Orbital Maneuvering Propulsion System 13. Expendable Fluids