Attachment_B_-_PACE-PROP-SPEC-0080-_06-14-2018.pdf

Effective Date: June 14, 2018

Expiration Date: June 14, 2023

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400-FORM-0002 (4/16/2014)

PACE-PROP-SPEC-0080, Revision -

Plankton, Aerosol, Cloud, ocean Ecosystem (PACE), Code 427

PACE Propellant Latch Valve Specification

Goddard Space Flight Center

Greenbelt, Maryland

National

Aeronautics and Space

Administration

Reviewed by GSC Export Control Office as not subject to export control, approved for public release

GSFC PACE CMO

06/14/2018

Released https://ipdtdms.gsfc.nasa.gov/

PACE Propellant Latch Valve Spec PACE-PROP-SPEC-0080, Revision -ii Check https://ipdtdms.gsfc.nasa.gov to verify that this is the correct version prior to use

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400-FORM-0002 (4/16/2014)

PACE Propellant Latch Valve Specification

Signature/Approval Page

Prepared By:

Christopher Hoffman

Reviewed By:

Noosha Haghani

Julian Ramirez-Brana

Gary Davis

Beth Weinstein

Jack Sanders

Gary Won

Timothy Johnson

Kenneth Harris

Daniel Mcguinness

Shavesha Rutledge

Henry Mulkey

George Bertholdt

Craig Stevens

Daniel Powers

Zachary Boblitt

Erik Laurila

David Sohl

Approved By:

Andre Dress

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Preface

This document is under Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) Mission configuration control. Changes to this document require prior approval of the PACE

Configuration Control Board (CCB) Chairperson or designee. Proposed changes shall be submitted to the PACE Configuration Management Office (CMO), along with supportive material justifying the proposed change. Changes to this document will be made by complete revision.

iv

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Change History Log

Revision Effective Date Description of Changes

(Reference the SCoRe & Approval Date)

Revision - 06/14/2018 Baseline Release following the approval of PACE-CCR-0312 v

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Table of TBDs/TBRs/TBSs

Action Item

No.

Location Summary Individual/

Organization

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Table of Contents

1.0 Introduction

1.1 General Information

1.2 Scope

2.0 Applicable Documents

3.0 Contract Description

3.1 PROPELLANT LATCH VALVE Description

4.0 Functional/Performance Requirements

4.1 Propellant latch valve Flight Unit Functional/Performance Requirements

4.1.1 Pressure

4.1.1.1 Maximum Expected Operating Pressure (MEOP)

4.1.1.2 Maximum Pressure Exposure

4.1.1.3 Proof Pressure

4.1.1.4 Burst Pressure

4.1.1.5 Interface Tube Design Pressure

4.1.1.6 Flow Rate/Pressure Drop

4.1.1.7 Back Relief Pressure

4.1.2 Leakage

4.1.2.1 Internal Leakage

4.1.2.2 External Leakage

4.1.3 Response Time

4.1.4 Position Indication

4.1.5 Coil Redundancy

4.1.6 Cycles

4.1.7 Filtration

4.2 Resource Allocations

4.2.1 Mass Allocation

4.2.2 NA

4.2.3 NA

4.2.4 Maximum Current Draw

4.3 Power

4.3.1 Primary (Unregulated) Power Input Requirements

4.3.1.1 Operating Voltage Range

4.3.1.2 Abnormal Voltages

4.3.2 Load Induced Noise Requirements

4.3.2.1 NA

4.3.2.2 Operational Current Transients

4.4 Electrical Grounding

4.4.1 Primary Power DC Isolation

4.4.2 NA

4.4.3 Internally Generated Secondary to Primary DC Isolation

4.4.4 Mechanical Contact Resistance

4.4.5 Mating Method

5.0 Physical Requirements

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5.1 Interface documentation

5.1.1 Mechanical Interface

5.1.2 Electrical Interface

5.2 Mass Properties

5.2.1 Component Masses

5.3 Physical Envelope

5.4 Mounting

5.4.1 Fastener Accessibility

5.4.2 Interface Tube

5.4.2.1 Dimensions

5.4.2.2 Material

6.0 Environmental Requirements

6.1 Mechanical Factors of Safety

6.2 Quasi-Static Acceleration

6.3 Frequency Requirement

6.3.1 Fundamental Launch Frequencies

6.4 Vibration

6.4.1 Sinusoidal Vibration

6.4.2 Random Vibration

6.5 Shock

6.6 NA

6.7 Transportation

6.7.1 Transportation Cleanliness

6.8 Pressure

6.8.1 Operating Pressure Range

6.9 NA

6.10 Ground Environments

6.11 Thermal Requirements

6.11.1 Flight Interface Design Temperature Limits

7.0 Cleanliness

7.1 Surface Contamination

7.1.1 Surface Contamination Levels at Delivery

7.1.1.1 Particulate Contamination

7.1.1.2 Molecular Contamination – Exposed Surfaces

7.1.1.3 Molecular Contamination – Covered Surfaces

7.1.1.4 External Cleanliness

7.1.1.5 Internal Cleanliness

7.1.2 Surface Contamination Generation

7.1.2.1 Particulate Generation

7.1.2.2 Molecular Generation

7.1.3 Cleanability

7.1.3.1 Cleanability – Sensitive Surfaces

7.1.3.2 Cleanability – Sensitive Surface Cleaning Methods

7.2 Electrostatic Cleanliness

7.2.1 Conductive Surface Ground Path

8.0 Design & Construction Requirements

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8.1 Parts, Materials & Processes (PMP)

8.1.1 EEE Parts

8.1.2 Materials

8.1.2.1 Material Conductivity

8.1.2.2 Material Limitations for Debris Casualty Area

8.1.2.3 Fluid Compatibility

8.2 Electrical

8.2.1 NA

8.2.2 Interface Requirements

8.2.2.1 Connector Selection

8.2.2.2 Minimum Wire Size

8.2.2.3 Wire Derating

8.2.2.4 Wire Composition

8.3 NA

8.4 NA

8.5 Identification and Marking

8.6 Workmanship

8.6.1 Workmanship Standards

8.6.2 Welding

8.7 Reliability and Mission Lifetime

8.7.1 Mission Life

8.8 Ground Handling

8.8.1 NA

8.8.2 NA

8.8.3 NA

8.8.4 NA

8.8.5 NA

8.8.6 NA

8.8.7 GSE Cleanliness

8.9 Interchangeability

9.0 Mechanical Design Requirements

9.1 Structural Requirements

9.1.1 Component Fatigue

9.1.2 Fracture Control Requirements

9.2 Fastening Systems

9.2.1 Fastener Performance Analysis

9.2.1.1 Factors of Safety

9.2.1.2 Supplemental Factor

9.2.1.3 Ultimate Design Loads

9.2.1.4 Yield Design Loads

9.2.1.5 Design Separation Load

9.2.2 Fastener Locking and Retention

9.2.2.1 Locking Features

9.2.2.2 Verification

9.2.2.3 Locking Features

9.2.2.4 Installation Torque Specification and Control

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9.2.3 Fastened Joints Criteria

9.2.3.1 Minimum and Maximum Preload

9.2.3.2 Analysis Addressing Potential Rupture

9.2.3.3 Ultimate Strength Analysis

9.2.3.4 Applied Shear Loading

9.2.3.5 Shear Loading

9.2.3.6 Simultaneous Applied Tensile and Shear Loads

9.2.3.7 Allowable Yield Tensile Load

9.2.3.8 Separation Analysis

9.2.3.9 Seal Analysis

9.3 Mechanism Design

9.3.1 Torque/Force Margins

9.3.2 Binding/Jamming/Seizing

9.3.2.1 Clearances

9.3.2.2 Tolerancing

9.3.2.3 Lubrication

9.3.3 Springs

9.3.4 NA

9.3.5 NA

9.3.6 NA

9.3.7 Mechanical Stops

9.3.8 Switches

9.3.9 Mechanism Performance and Strength Analysis

9.3.10 Mechanism Installation

10.0 NA

11.0 Verification Requirements

11.1 Verification Methods

11.1.1 Inspection

11.1.2 Analysis

11.1.3 Test

11.2 Inspection Requirements

11.2.1 Visual Inspection

11.2.2 Physical Measurement

11.2.3 Documentation Search

11.3 Analysis Requirements

11.4 Test Requirements

11.4.1 Definitions

11.4.2 Test Factors

11.4.3 Test Tolerances

11.4.4 Test Restrictions

11.4.4.1 Failure During Tests

11.4.4.2 Modification of Hardware

11.4.4.3 External Adjustment

11.4.4.4 Re-Test Requirements

11.5 Required Tests

11.5.1 NA

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11.5.2 Mass Properties Measurement

11.5.3 Static Loads/Strength Test

11.5.3.1 Sine Burst

11.5.3.2 Static Pull

11.5.4 Sine Sweep Survey

11.5.5 Sine Vibration

11.5.6 Random Vibration

11.5.7 NA

11.5.8 Proof Pressure Test

11.5.9 Shock

11.5.10 NA

11.5.11 Thermal Cycling Test

11.5.11.1 Thermal Vacuum Test Parameters

11.5.11.2 Thermal Vacuum Test Profile

11.5.12 NA

11.5.13 NA

11.5.14 NA

11.5.15 NA

11.5.16 Flow/Pressure Drop

11.5.17 Back Pressure Relief

11.5.18 Internal Leakage

11.5.19 External Leakage

11.5.20 Response Time

Appendix A Abbreviations and Acronyms xi Check https://ipdtdms.gsfc.nasa.gov to verify that this is the correct version prior to use

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List of Figures Figure Page

Figure 6-1. Sine Vibration Environment

Figure 6-3. Shock Envelope

Figure 11-1. Thermal Vacuum Profile

List of Tables Table Page

Table 2-1. Applicable Documents

Table 6-1. Factors of Safety

Table 6-2. Latch Valve Design Limit Loads

Table 6-3. Latch Valve Sine Vibration Environment

Table 6-4. Latch Valve Random Vibration Environment, (22.7 kg, or less)

Table 6-6. Qualification Level Shock Response Spectrum

Table 6-9. Transportation Loads

Table 6-10. Latch Valve Temperature Limits

Table 8-1. Limited materials for debris casualty area

Table 9-1 Factors of Safety

Table 11-1. Test Factors and Durations

Table 11-2. Test Tolerances

Table 11-3. Thermal Vacuum Test Parameters

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1.0 INTRODUCTION

1.1 GENERAL INFORMATION

The Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission is a strategic climate continuity mission that will extend the high quality ocean ecological, ocean biogeochemical, cloud, and aerosol particle data records begun by NASA in the 1990s. The mission will be capable of collecting radiometric and polarimetric measurements of the ocean and atmosphere, from which these biological, biogeochemical, and physical properties will be determined. PACE data products will not only add to existing critical climate and Earth system records, but also answer new and emerging advanced science questions related to Earth’s changing climate.

1.2 SCOPE

This specification describes the electrical, mechanical, environmental, and verification testing requirements for a space-qualified Propellant Latch Valve for the NASA Goddard Space Flight

Center (GSFC) PACE Mission.

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2.0 APPLICABLE DOCUMENTS

The following documents and drawings in effect on the day this specification was signed shall apply to the fabrication and to the electrical, mechanical, and environmental requirements of the propellant latch valve to the extent specified herein. In the event of conflict between this specification and any referenced document, this specification will govern, with the exception of the PACE propellant latch valve Statement of Work (PACE-PROP-SOW-0046), in which case the Statement of Work takes precedence.

The following is a list of the applicable specifications and publications.

Table 2-1. Applicable Documents

Document Number Title

PACE-PROP-SOW-0046 PACE Propellant Latch Valve Statement of Work

(SOW)

PACE-PROP-LIST-0028 PACE Propellant Latch Valve Deliverables Items

List and Schedule (DILS)

NASA-STD-5001B Structural Design And Test Factors Of Safety For

Spaceflight Hardware

NASA-STD-8719.24 NASA Expendable Launch Vehicle Payload Safety

Requirements

NASA-STD-6016 Standard Materials and Processes Requirements for

Spacecraft

NASA-HDBK-7005 Dynamic Environment Criteria

NASA-STD-7001 Payload Vibroacoustic Test Criteria

IEST-STD-CC-1246E Product Cleanliness Levels And Contamination

Control Program

ASTM E-595-15 Standard Test Method for Total Mass Loss and

Collected Volatile Condensable Materials from

Outgassing in a Vacuum Environment

MIL-DTL-5541 Chemical Conversion Coatings on Aluminum and

Aluminum Alloys

MIL-A-8625F Anodic Coatings for Aluminum and Aluminum

Alloys

EEE-INST-002 Instructions for EEE Parts Selection, Screening, Qualification, and Derating

GSFC-STD-7000A General Environmental Verification Standard

(GEVS)

NASA-STD-5019A Fracture Control Requirements for Spaceflight

Hardware

NASA-STD-5020 Requirements for Threaded Fastening Systems in

Spaceflight Hardware

MIL-PRF-26536G Performance Specification Propellant, Hydrazine

JSC-SPEC-C-20C Water, High Purity, Specification for

MIL-PRF-27401G Propellant, Nitrogen, Pressurizing Agent

MIL-PRF-27407D Propellant, Helium, Pressurizing Agent

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Document Number Title

MIL-PRF-27415C Propellant Pressurizing Agent, Argon

FED-STD-TT-I-735 Isopropyl Alcohol

SAE AS567NASM 33540 Safety Cable, Safety Wire, Key Washers, and Cotter

Pins for Propulsion Systems, General Practices for

Use of Safety Wiring, Safety Cabling, Cotter

Pinning, General Practices for

541-WI-5330.1.41SAE

AS567

Fastener Locking Using Arathane 5753Safety Cable, Safety Wire, Key Washers, and Cotter Pins for

Propulsion Systems, General Practices for Use of

MSFC-STD-3029 Guidelines for the Selection of Metallic Materials for

Stress Corrosion Cracking Resistance in Sodium

Chloride Environments

A541-WI-5330.1.41 Fastener Locking Using Arathane 5753

ASTM A269 Standard Specification for Seamless and Welded

Austenitic Stainless Steel Tubing for General

Service

AMS 5647 Aerospace Material Specification for 304L Stainless

Steel

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3.0 CONTRACT DESCRIPTION

3.1 PROPELLANT LATCH VALVE DESCRIPTION

The Propellant Latch Valve is a latching valve device that is capable of stopping or starting the supply of propellant by electromagnetically opening and closing the valve. Power is only required for valve opening, closing and the position indicator. Once either opened or closed, the latch valve will remain in its last commanded position without applying further power.

The PACE Propulsion Subsystem will use two (2) latch valves. There will be one (1) latch valve to isolate the primary and redundant per thruster manifolds. Furthermore, one (1) spare will be procured.

Each latch valve design shall either have been qualified for space flight or the vendor shall designate one (1) unit as protoflight to test at the qualification levels listed in this document.

Latch valve designs that have been qualified previously shall include qualification documentation as described in the Latch Valve SOW PACE-PROP-SOW-0046.

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4.0 FUNCTIONAL/PERFORMANCE REQUIREMENTS

This section defines the functional and performance requirements for the Propellant Latch Valve as defined in Section 4.1.

4.1 PROPELLANT LATCH VALVE FLIGHT UNIT

FUNCTIONAL/PERFORMANCE REQUIREMENTS

4.1.1 Pressure

4.1.1.1 Maximum Expected Operating Pressure (MEOP)

The MEOP shall be 400 psia (27.58 bar) at 50°C, on orbit.

4.1.1.2 Maximum Pressure Exposure

Due to pressure back relief, the latch valve may encounter pressure as high as 550psia (37.92 bar). The latch valve shall withstand, in both open and closed latching positions, the maximum pressure exposure without increased leakage or damage

4.1.1.3 Proof Pressure

Proof pressure capability of the propellant latch valve shall be at least 825psia (56.88 bar). This is a proof factor of 1.5, including back pressure relief.

If necessary, the proof pressure shall also include a factor to account for any difference in material properties between the proof test temperature and the operating temperature range.

4.1.1.4 Burst Pressure

Burst pressure of the propellant latch valve shall be at least 1375psia (94.80 bar). This is a proof factor of 2.5, including back pressure relief.

Burst pressure is the pressure that, once applied to the particular filters, results in exceeding its ultimate strength.

4.1.1.5 Interface Tube Design Pressure

4.1.1.5.1 Proof Pressure

The interface tube design proof pressure capability shall be at least 825psia (56.88 bar). This is a proof factor of 1.5, including back pressure relief.

4.1.1.5.2 Burst Pressure

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The interface tube design burst pressure capability shall be at least 2200psia (151.68 bar). This is a proof factor of 4.0, including back pressure relief.

4.1.1.6 Flow Rate/Pressure Drop

The latch valves shall be capable of providing the flow rates of 0.1433 lb/s (0.065 kg/s) of water as a minimum. At these flow rates, the pressure drop for each latch valve shall be less than or equal to 5.0 psid (34.5 kPa).

These requirements shall apply for when the inlet filters are clean. Pressure drop and flow rate shall be quantified for the case of filtration capacity being reached.

4.1.1.7 Back Relief Pressure

The latch valve shall have a back relief pressure of less than or equal to 150 psid (10.34 bar).

Back relief pressure is the pressure differential between the downstream and the upstream fluids required to force the latch valve open to relieve downstream pressure.

4.1.2 Leakage

4.1.2.1 Internal Leakage

The Internal leakage rate of the latch valve shall not exceed 5 scch of GHe.

4.1.2.2 External Leakage

The external leakage rate of the latch valve shall not exceed 10-6 sccs of GHe.

4.1.3 Response Time

The opening and closing response time for each latch valve shall be less than 120 ms at the

MEOP given in Section 4.1.1.1 throughout the temperature and voltage range specified herein.

4.1.4 Position Indication

The latch valve shall have at a minimum a single position indicator which gives positive confirmation that the valve is either open or closed.

The position indicator shall consist of closed, open, and common leads.

4.1.5 Coil Redundancy

Coil redundancy is not required for PACE propellant latch valves.

Latch valve design that have been qualified previously with coil redundancy, that meet the requirements in this SPEC should be considered.

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4.1.6 Cycles

The latch valve shall be qualified for at least 3,000 functional cycles at exposure pressures and temperatures given herein. The contractor shall provide data to show that the latch valve design has successfully operated in a manner that verifies the capability to achieve this cycle life.

4.1.7 Filtration

The latch valve shall have an inlet filter with a filtration rating of greater than or equal to

30 microns.

The inlet filter shall be sized properly to provide adequate protection for the latch valve seat.

4.2 RESOURCE ALLOCATIONS

4.2.1 Mass Allocation

Each latch valve shall have a mass of less than or equal to 0.9 kg (1.98 lbm), including the valve and all electrical lead wires.

4.2.2 NA

4.2.3 NA

4.2.4 Maximum Current Draw

The latch valves shall draw no more than 1.2 A at 34 V input voltage.

4.3 POWER

4.3.1 Primary (Unregulated) Power Input Requirements

4.3.1.1 Operating Voltage Range

The Propulsion Latch Valve shall be designed to operate over the bus voltage range of +24 to

+34 VDC at their primary power inputs.

4.3.1.2 Abnormal Voltages

The latch valve shall survive without electrical overstress after exposure to an anomalous voltage range of 0 to +40 VDC for 500 ms duration. This requirement is to be verified by analysis or test of a non-flight unit.

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4.3.2 Load Induced Noise Requirements

4.3.2.1 NA

4.3.2.2 Operational Current Transients

a. The latch valve operational current transients shall be less than or equal to 5A above the steady state current for a period of less than 2 millisecond.

b. The rate of change of the current shall be less than or equal to 20 milliamperes/microsecond.

4.4 ELECTRICAL GROUNDING

4.4.1 Primary Power DC Isolation

At the latch valve primary power interfaces, primary power and primary power returns shall be isolated from signal grounds and from the component chassis by a DC resistance of greater than or equal to 1 MΩ.

4.4.2 NA

4.4.3 Internally Generated Secondary to Primary DC Isolation

Secondary power (or signal) inputs shall be isolated from primary power by a DC resistance of greater than 1 MΩ.

4.4.4 Mechanical Contact Resistance

The DC resistance of the mechanical contact between two conductive mating surfaces (internal to the component) shall be less than or equal to 2.5 mΩ DC resistance.

4.4.5 Mating Method

The primary mating method for a PACE component is metal-to-metal contact between component mounting feet (or base plate) and the spacecraft structure.

See section 5.4 for details.

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5.0 PHYSICAL REQUIREMENTS

5.1 INTERFACE DOCUMENTATION

The contractor shall use metric units when interfacing with NASA GSFC including any drawings, documents, models, except for the following cases:

Heritage Hardware: Hardware that has been previously qualified, or of similar design heritage, may be specified in English units where use of metric equivalents would lead to additional cost to the program.

Fasteners: Although bolt patterns will be defined using metric dimensioning, use of

English fasteners (with hole dimensioning and tolerancing) is permitted.

Angular Measurement: Angular measurement may be expressed in degree of arc or in an appropriate subdivision of degree of arc such as second of arc (arc-sec) when advantageous to application.

5.1.1 Mechanical Interface

The mounting interface shall be defined in the Mechanical Interface Control Drawing (MICD), which will be developed between the contractor and NASA GSFC.

5.1.2 Electrical Interface

The electrical interface shall be defined in the Electrical Interface Control Document (EICD), which will be developed between the contractor and NASA GSFC. The EICD may be combined with the MICD.

5.2 MASS PROPERTIES

5.2.1 Component Masses

See Section 4.2.1.

5.3 PHYSICAL ENVELOPE

The physical envelope of the latch valve shall be less than 2.75” X 4.25” X 9” (6.88cm X

10.80cm X 22.90cm) not including electrical lead wire length.

5.4 MOUNTING

Each latch valve will be hard-mounted on a mechanical surface of the spacecraft structure.

5.4.1 Fastener Accessibility

The latch valve shall be designed such that it can be fastened or removed by accessing fasteners from above without any disturbance.

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5.4.2 Interface Tube

5.4.2.1 Dimensions

Each latch valve shall have interface tube with the dimension of 0.375±0.004 inches

(9.525±0.1016 mm) OD with a 0.028±0.004 inches (0.7112±0.1016 mm) wall thickness and a length of no less than 1.5 inches (38.1 mm).

5.4.2.2 Material

The interface tube shall be SS 304L per AMS-QQ-S-763.

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6.0 ENVIRONMENTAL REQUIREMENTS

Environmental design requirements for the spacecraft components are specified in this section.

The latch valve shall meet its performance requirements in section 4.0 during and after exposure to the environments specified in this section.

6.1 MECHANICAL FACTORS OF SAFETY

a. The latch valve, as well as Mechanical Ground Support Equipment (MGSE), shall demonstrate positive Margins of Safety under limit loads for all yield and ultimate failures using the Factors of Safety (FS) defined in b.

c.

d. Table 6-1. Margin of Safety (MS) is defined as follows:

MS = (Allowable Stress (or Load) / (Applied Limit Stress (or Load) x FS)) -1

Table 6-1. Factors of Safety

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e. Primary and secondary structure comprised of composite materials, Beryllium, bonded joints and/or bonded inserts shall be proof tested to 1.25 x Limit Load; qualification by analysis only is not acceptable. Actual flight component testing is preferred, but testing of representative sets of hardware with a similarity qualification argument can be used if approved by the NASA/GSFC COR.

6.2 QUASI-STATIC ACCELERATION

Quasi-static acceleration represents the combination of steady-state accelerations and the low frequency mechanically transmitted dynamic accelerations that occur during launch.

The latch valve shall be designed to withstand the quasi-static design limit loads defined in the mass-acceleration curve (MAC) shown in Table 6-2 without damage or degradation of performance. The design loads shown below will be updated based on the results of coupled loads analysis.

Linear interpolation should be used between breakpoints to determine the appropriate limit load as a function of latch valve weight. Note that these design limit loads are intended to cover only the low frequency launch environment and must be used in conjunction with the random vibration environments to assess structural margins.

Table 6-2. Latch Valve Design Limit Loads

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6.3 FREQUENCY REQUIREMENT

6.3.1 Fundamental Launch Frequencies

The latch valve shall have a fundamental frequency greater than 100 Hz when hard mounted at its spacecraft interface. Any component, which fails to meet the specified fundamental frequency, must supply a finite element model, correlated to modal survey test results up to 50

Hz, to be used in coupled loads analyses. Requirements for the submitted finite element model are in the SOW and discussed in Section 11.5.4.

6.4 VIBRATION

6.4.1 Sinusoidal Vibration

The latch valve shall undergo qualification, protoflight or acceptance (level depends on qualification status of unit) sine vibration testing on all three axes at the levels shown in Table

6-3. Stiff components showing a first mode greater than 150Hz can be exempted from sine vibration testing upon approval by the NASA/GSFC COR. A generic sine vibration specification is provided for Protoflight (PFT), Qualification (QT) and Acceptance (AT) levels applied at the PACE to latch valve interface. See Section 11.4.1 for definitions of Protoflight, Qualification, and Acceptance.

Table 6-3. Latch Valve Sine Vibration Environment

Frequency Protoflight, Qual Level Flight, Acceptance Level

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5-20 Hz 0.63 in (double amplitude) 0.50 in (double amplitude)

20-100 Hz 12.5 G 10.0 G

Figure 6-1. Sine Vibration Environment

Levels may be notched to not exceed 1.25 times the design limit load outlined in section 6.2.

Peak levels at the low end of the frequency range (5 – 20 Hz typically) may be ramped up as needed to accommodate shaker table displacement limitations.

6.4.2 Random Vibration

a. The latch valve shall demonstrate its ability to meet its performance requirements after being subjected to the random vibration environment in Table 6-4, for components weighing 22.7 kg (50 lb) or less, applied at the Spacecraft to latch valve interface.

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Table 6-4. Latch Valve Random Vibration Environment, (22.7 kg, or less)

Frequency ASD Level (g2/Hz)

(Hz) Qualification Acceptance

20-50

50-800

800-2000

0.026

+6 dB/oct

0.16

-6 dB/oct

0.026

0.013

+6 dB/oct

0.08

-6 dB/oct

0.013

Overall 14.1 Grms 10.0 Grms

This environment will be updated with random vibration analysis. Note for lightweight latch valve, the highest design loads may be from this random vibration environment.

b. The contractor shall provide random vibration analysis along with static loads analysis.

Please see NASA-HDBK-7005 and NASA-STD-7001 for more information.

During the test, the test input level will be reduced (notched) at critical frequencies, if required, to limit the random vibration loads and/or acceleration responses to 3 dB above design limit levels.

c. Notching shall be limited to -12 dB of the original input and to a bandwidth of less than

100 Hz to limit the random vibration responses to 3dB above design limit levels.

Notching beyond these limits will require NASA/GSFC COR approval.

6.5 SHOCK

a. The latch valve shall be designed to meet its performance requirements after being subjected to the shock environment in Table 6-5, applied at the latch valve interface to the PACE spacecraft structure.

Table 6-5. Qualification Level Shock Response Spectrum

Freq (Hz) SRS (G)

100 100

800 1700

8000 1700

10000 2200

b. A shock susceptibility and attenuation assessment shall be performed on all Spacecraft components. If the flight shock environment as shown on a Shock Response Spectra

(SRS) plot (Q=10) is enveloped by the curve shown below (Figure 6-2), then the shock

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environment can be considered benign and there is low risk in deferring the shock test to the Observatory level.

Figure 6-2. Shock Envelope

c. Analysis supporting this conclusion (i.e. deferral of shock testing) shall be provided to the NASA/GSFC COR for review.

d. Any component determined to be susceptible to the shock environment (e.g., shock levels are above the curve) shall have shock testing performed at the component level

(preferably on a qualification unit).

e. Component self-induced shock testing shall be accomplished by two actuations at the component level for each self-induced shock source (in order to account for the scatter associated with the actuation of the device) for the first flight unit, and a single actuation on subsequent units.

6.6 NA

6.7 TRANSPORTATION

In addition to the launch loads shown above, the latch valve shall also be designed to withstand the maximum transportation loads shown in Table 6-6 without damage or degradation of performance.

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Table 6-6. Transportation Loads

6.7.1 Transportation Cleanliness

Materials and enclosure used for transportation and storage shall not generate molecular or particle contaminants or degrade the surface cleanliness of the item or adjacent items

6.8 PRESSURE

6.8.1 Operating Pressure Range

The latch valve shall be designed to meet all performance requirements while operating over an external pressure range of 1.08 x 105 N/m2 (813 Torr) to 1.3 x 10-12 N/m2 (1 x 10-14 Torr).

6.9 NA

6.10 GROUND ENVIRONMENTS

a. The latch valve shall meet all of their performance requirements during exposure to air temperature between +5 and +30 degrees C and relative humidity between 30% and 70%.

b. After being powered “OFF” and exposed to air temperatures of +5 to +30 degrees C and relative humidity of 0 to 70%, the latch valve shall meet all of its performance requirements.

6.11 THERMAL REQUIREMENTS

6.11.1 Flight Interface Design Temperature Limits

The Latch Valve shall be capable of surviving indefinitely, without damage or permanent performance degradation, when its temperatures are within the limits shown in Table 6-7.

Table 6-7. Latch Valve Temperature Limits

Minimum Temperature (ºC) Maximum Temperature (ºC)

Operational (In Spec) +12 +40

Protoflight/Qualification (In Spec) +8 +50

Survival (Unpowered) +8 +50

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7.0 CLEANLINESS

The requirements in this section ensure the cleanliness of the latch valve at delivery, so as not to adversely affect its own performance, as well as not be a source of contamination to other items, including not generating contaminants following delivery in excess of that permitted below by virtue of its design, materials of construction, or operation.

7.1 SURFACE CONTAMINATION

7.1.1 Surface Contamination Levels at Delivery

7.1.1.1 Particulate Contamination

The Latch Valve shall meet IEST-STD-CC1246E VC-0.5-1000 + UV, or equivalent, when inspected with both UV and white light in a darkened room.

7.1.1.2 Molecular Contamination – Exposed Surfaces

If the Latch Valve has surfaces exposed to the space environment, all such surfaces shall meet a molecular surface cleanliness level of R3.3E-1 on all external and critical surfaces, when tested in accordance with IEST-STD-CC1246E VC-0.5-1000 + UV, or equivalent.

7.1.1.3 Molecular Contamination – Covered Surfaces

All Latch Valve surfaces not exposed to the space environment shall meet IEST-STD-CC1246E

VC-0.5-1000 + UV, or equivalent, when inspected in a darkened room with white and UV light.

The surfaces shall be free of molecular contamination – for example films, spots, or other.

7.1.1.4 External Cleanliness

All hardware surfaces shall be verified to be “visibly clean, highly sensitive” per JSC-SN-C-

0005C or equivelant, prior to delivery to NASA/GSFC. This is accomplished by maintaining all hardware in a double bag for storage.

7.1.1.5 Internal Cleanliness

The propulsion components, lines, and fittings shall be cleaned, and verified internally clean, to level 100R1 per IEST-STD-CC1246E (as modified by the following: no metal particles allowed above 25 um) prior to integration in the system.

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7.1.2 Surface Contamination Generation

7.1.2.1 Particulate Generation

The latch valve contractor shall not employ any of the following particle generating materials or processes into the latch valve design or construction without prior approval by the NASA/GSFC

COR:

Paints prone to shedding due to large paint pigment molecules, overspray, poor adhesion, etc.

Dry lubricants (e.g. molybdenum disulfide).

Surfaces prone to corrosion or oxides because of a lack of corrosion protection or dissimilar metals in close contact.

Fabrics with brittle constituents (e.g., composites, graphite or glass).

Perforated materials when material is highly susceptible to tear propagation (e.g., multi-layer insulation (MLI)).

Metal oxides (bare [untreated] aluminum and magnesium, iron, non-corrosion resistant steel, etc.).

Braided metallic or synthetic wires, ropes, slings, etc. unless measures have been taken to contain any broken filaments or fibers (sheathing, sealing with polymers, covering, etc.).

Woven materials especially cut or unfinished ends (metal braid, EMI shielding, lacing cord, expando sleeving), unless measures have been taken to prevent fraying or generation of particles (cut with a hot knife, seal with polymer, bag, etc.).

Materials with thin films known to erode or crack or flake when subjected to normal handling (e.g., indium tin oxide [ITO] or other rigid or brittle semiconductor or ceramic coating on flexible substrates, Teflon, MLI, etc.).

Foams, highly textured materials.

Trapped debris in holes.

7.1.2.2 Molecular Generation

7.1.2.2.1 Material Selection

The latch valve materials shall have a total mass loss (TML) less than 1.00% and a collected volatile condensable mass (CVCM) less than 0.10%, when measured in accordance with ASTM

E-595 unless a materials usage agreement has been generated and approved by the NASA/GSFC

COR.

7.1.2.2.2 Material Selection - Silicones

Silicones on external (to the spacecraft) surfaces shall not be exposed to the space environment unless approved by the NASA/GSFC COR. Silicones should be avoided or minimized. It is highly recommended that silicones be baked out at a high temperature prior to integration into the system to prevent extended bakeouts of the entire assembly.

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7.1.3 Cleanability

7.1.3.1 Cleanability – Sensitive Surfaces

If any surfaces are not cleanable with Isopropyl alcohol and polyester wipes or light vacuuming, they shall be identified on the MICD.

7.1.3.2 Cleanability – Sensitive Surface Cleaning Methods

Alternate cleaning methods shall be identified and appropriate documentation provided for any surfaces that are not cleanable with Isopropyl alcohol.

7.2 ELECTROSTATIC CLEANLINESS

7.2.1 Conductive Surface Ground Path

All latch valve external conductive surfaces shall be connected to the spacecraft interface with a resistance less than 5 ohms, either through the use of ground wire(s) or through metal-to-metal mounting contact.

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8.0 DESIGN & CONSTRUCTION REQUIREMENTS

8.1 PARTS, MATERIALS & PROCESSES (PMP)

8.1.1 EEE Parts

The latch valve wiring will adhere to EEE part compliance. The latch valve contractor’s Quality

Assurance system for EEE parts will be in accordance with the requirements in the SOW, PACE-

PROP-SOW-0046. For additional details on EEE parts compliance specific to harness wires, see section 8.2 in this document.

8.1.2 Materials

The latch valve will be comprised of materials and processes in accordance with the requirements in the SOW, PACE-PROP-SOW-0046.

8.1.2.1 Material Conductivity

All parts should be passivated and mounting surfaces on latch valve shall be conductive as defined in Section 4.4.

8.1.2.2 Material Limitations for Debris Casualty Area

The Latch Valve shall report the mass, dimensions, and use of materials shown in Table 8-1.

Table 8-1. Limited materials for debris casualty area

Material Quantity

Titanium Mass > 50g

Steel Mass > 50g

Inconel Mass > 50g

Invar Mass > 50g

Materials with melting points above 1200° C

(1473 K)

Mass > 50g

8.1.2.3 Fluid Compatibility

All materials shall be compatible with prolonged exposure to the following fluids:

De-ionized water per JSC-SPEC-C-20 or equivalent

Hydrazine per MIL-PRF-26536G, High Purity

GHe per MIL-PRF-27407D

Grade A, Ar per MIL-PRF-27415C

Grade A, GN2 per MIL-PRF-27401G

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8.2 ELECTRICAL

8.2.1 NA

8.2.2 Interface Requirements

8.2.2.1 Connector Selection

The thrusters shall be delivered with at least 1 meter of flying lead harness length for the entire bundle (and no connector).

8.2.2.2 Minimum Wire Size

No wire smaller than AWG #26 shall be used.

8.2.2.3 Wire Derating

The current carrying capacity of the wires shall be derated for continuous operation at the required current levels in a vacuum, as defined in Section W1 of EEE-INST-002 or equivalent.

8.2.2.4 Wire Composition

Wire conductors shall be copper or a copper alloy. The wires may be tinned or plated with suitable materials as agreed with the NASA GSFC COR.

8.3 NA

8.4 NA

8.5 IDENTIFICATION AND MARKING

Each unit shall be permanently marked with the part number and a unique sequential serial number in the area designated on the interface control drawing in a manner to be approved by the

NASA/GSFC COR.

All markings shall use alcohol proof ink, engraving, or laser etching.

The latch valve shall be marked to include but not limited to the following, Vendor Part number

Vendor Name

Vendor Serial Number

Indication of Flow Direction (Arrow)

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8.6 WORKMANSHIP

8.6.1 Workmanship Standards

The workmanship standards and processes outlined in the SOW, PACE-PROP-SOW-0046 shall be used.

8.6.2 Welding

All weld procedures and weld inspection procedures shall be approved by NASA/GSFC and in compliance with SOW, PACE-PROP-SOW-0046.

Test records such as dye penetrant, x-rays, etc. shall all be retained.

8.7 RELIABILITY AND MISSION LIFETIME

8.7.1 Mission Life

The latch valve shall meet all performance specifications through two (2) years of ground testing and three (3) years of operation in space, following a two (2) month commissioning period.

8.8 GROUND HANDLING

8.8.1 NA

8.8.2 NA

8.8.3 NA

8.8.4 NA

8.8.5 NA

8.8.6 NA

8.8.7 GSE Cleanliness

All Ground and Test support equipment shall be compatible with the flight component and the environment where the flight component or test component will reside (cleanroom, thermal vacuum chamber, vibration cell, etc.)

8.9 INTERCHANGEABILITY

The latch valve shall be directly interchangeable in form, fit, and function with other latch valves of the same part number.

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9.0 MECHANICAL DESIGN REQUIREMENTS

For additional guidance on the design and analysis of threaded fastening systems in NASA spaceflight hardware, consult NASA-STD-5020, “Requirements for Threaded Fastening Systems in Spaceflight Hardware”.

9.1 STRUCTURAL REQUIREMENTS

The latch valve shall be capable of withstanding all worst-case load conditions to which it may be exposed, without requiring additional recalibration or realignment and by maintaining structural integrity (i.e., positive structural margins). This includes handling and transportation, test, pre-launch operations, launch, and on-orbit operations.

Structural margins shall be expressed using the following formula:

𝑀𝑆 =

(𝐴𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 𝐿𝑜𝑎𝑑 𝑜𝑟 𝑆𝑡𝑟𝑒𝑠𝑠)

(𝐹𝑎𝑐𝑡𝑜𝑟 𝑜𝑓 𝑆𝑎𝑓𝑒𝑡𝑦)𝑥 (𝐿𝑖𝑚𝑖𝑡 𝐿𝑜𝑎𝑑 𝑜𝑟 𝑆𝑡𝑟𝑒𝑠𝑠) − 1

For metallic and/or composite materials, selection and derivation of material design allowables shall follow the requirements defined in NASA-STD-6016, Standard Materials and Processes

Requirements for Spacecraft as described in the SOW Section 7.8.5.

For glass/ceramic materials, selection and derivation of material design allowables shall follow the requirements outlined in NASA-STD-5001, “Structural Design and Test Factors of Safety for

Spaceflight Hardware”.

9.1.1 Component Fatigue

Thin-walled, highly loaded metallic latch valve components serving as springs, flexures and other compliance devices under cyclic loading shall show sufficient fatigue strength for 4 times the number of mission cycles (including ground testing, launch and on-orbit loading).

9.1.2 Fracture Control Requirements

The use of materials that are susceptible to brittle fracture or stress-corrosion cracking require development of, and strict adherence to, special procedures to prevent problems.

If materials are used for structural applications that are not listed in Table 1 of MSFC-STD-3029, a Materials Usage Agreement (MUA) shall be approved by the NASA/GSFC COR.

Fracture control requirements (per NASA-STD-5019) shall apply to the following elements only:

(1) Pressure vessels, dewars, lines, and fittings (per NASA-STD 8719.24)

(2) Castings (unless hot isostatically pressed and the flight article is proof tested to 1.25

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times limit load)

(3) Weldments

(4) Parts made of materials on Tables II or III of MSFC-STD-3029 if under sustained tensile stress

(5) Parts made of materials susceptible to cracking during quenching

(6) Nonredundant, mission-critical preloaded springs loaded to greater than 25 percent of ultimate strength

All glass elements that are stressed above 10% of their ultimate tensile strength shall also be shown by fracture analysis to satisfy "Safe-life" or "Fail-safe" conditions or be subjected to a proof loads test at 1.0 times limit level.

9.2 FASTENING SYSTEMS

9.2.1 Fastener Performance Analysis

9.2.1.1 Factors of Safety

Factors of safety for fastener strength analysis shall be as specified in

Table 6-1.

9.2.1.2 Supplemental Factor

A supplemental factor, referred to as a fitting factor (greater than or equal to 1.0), shall be applied. See NASA-STD-5020, section 4.1(b) as a reference.

9.2.1.3 Ultimate Design Loads

All threaded fastening systems shall withstand ultimate design loads in conjunction with the applicable maximum expected range of environmental conditions without rupture.

9.2.1.4 Yield Design Loads

All threaded fastening systems shall withstand yield design loads in conjunction with the applicable maximum expected range of environmental conditions without detrimental yielding.

Detrimental yielding is yielding that affects the fit, form, function, or integrity of the structure.

See NASA-STD-5020, section 6.3 as reference.

9.2.1.5 Design Separation Load

Mechanical joints using threaded fastening system hardware shall withstand the design separation load in conjunction with applicable maximum or minimum temperatures without

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separation, using a separation factor of safety (FSsep) of 1.0 for non-separation critical joints, FSsep=1.25 for non-catastrophic separation critical joints, and FSsep=1.4 for catastrophic separation critical joints. See NASA-STD-5020, section 4.3 for reference.

NOTE: A separation critical joint is one that would not function properly if separated; e.g., a fluid or gas would penetrate a seal at an unacceptable rate, or an instrument would fail to perform properly due to misalignment. Further, ‘catastrophic’ here refers to risk/loss of human life, such as could occur if a pressurized component failed or released a toxic substance due to joint separation.

NASA-STD-5020 Section 6.5 provides criteria for separation analysis and guidance for fitting factor application.

9.2.2 Fastener Locking and Retention

9.2.2.1 Locking Features

9.2.2.1.1 Locking Feature Minimum

Regardless of the magnitude of preload, each threaded fastening system in spaceflight hardware shall incorporate a minimum of one locking feature that does not depend upon preload to function.

Devices such as jam nuts may not be suitable locking features to satisfy this requirement if they require preload to function effectively, or if a change in preload could compromise the locking performance. A redundant locking feature may be advisable for some joints as described in FAA

AC 20-71, “Dual Locking Devices on Fasteners".

9.2.2.1.2 Locking Feature Verification

Locking features shall be verifiable per Section 7.6 of NASA-STD-5020, or NASA/GSFC COR approved procedure.

9.2.2.1.3 Locking Feature Installation

Mechanical locking features such as cotter pins, safety wire, and safety cable, shall be installed per National Aerospace Standard NASM 33540, “Safety Wiring, Safety Cabling, Cotter Pinning, General Practices for”, and Society of Automotive Engineers International SAE AS567, “Safety

Cable, Safety Wire, Key Washers, and Cotter Pins for Propulsion Systems, General Practices for

Use of”, or NASA/GSFC COR approved procedure.

9.2.2.1.4 Snap Ring & Cotter Pin Use Limitation

Snap rings and cotter pins shall not be used where other acceptable retention methods are possible.

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