LNEXT-SYS-DESC-0032 Rev - LETM 20240507.docx.pdf

DOORS EXPORT

National Aeronautics and Space Administration

Goddard Space Flight Center Greenbelt, Maryland

LNEXT-SYS-DESC-0032, Revision -

Landsat Next, Code 426

Landsat Next (LNext) Reference Environmental Test Matrix (LETM)

5/7/2024

LETM LNEXT-SYS-DESC-0032 Revision -ii

Landsat Next (LNext) Reference Environmental Test Matrix (LETM) Signature/Approval Page

Prepared by:

Electronic Signature in TDMS Approval Date in TDMS Michael Pryzby Date Landsat Next Space Environments Engineer NASA/GSFC, Code 426

Approved by:

James Pontius Date Landsat Next Project Manager NASA/GSFC, Code 426

Approved by:

Evan Webb Date Landsat Next Mission System Manager NASA/GSFC, Code 599

Electronic Signatures available online at: https://ipdtdms.gsfc.nasa.gov iii

CM Foreword This document is a Landsat Next Project Signatured Controlled document. Changes to this document require prior approval via a Signature Controlled Change Request (SCoRe). Proposed changes shall be submitted to the Landsat Next CM Office (CMO), along with supportive material justifying the proposed change. Changes to this document will be made by complete revision.

Questions or comments concerning this document should be addressed to:

NASA/Goddard Space Flight Center Landsat Next Project Office, Code 426 Attention: Configuration Management Office Greenbelt, Maryland 20771 iv

Change History Log v

List of TBDs/TBRs Hyperlink to TBx Location Summary Ind.

Name/Org.

Due Date

TBx-1 Section 2.4.3

The Launch Segment will provide the assets and services associated with the Launch Vehicle (LV) and the constellation-to-LV integration. This will include the LV; all Launch Vehicle-Ground Support Equipment (LV-GSE), property, and facilities to integrate the constellation to the LV and verify their integration; and prelaunch testing with ground-based functions. The launch vehicle and launch site are TBD. The three observatories comprising the Landsat Next constellation will be launched together on the same launch vehicle.

LSP 5/2028

vi

Table of Contents SIGNATURE/APPROVAL PAGE ................................................................................................ II CM FOREWORD ..........................................................................................................................III CHANGE HISTORY LOG .......................................................................................................... IV

LIST OF TBDS/TBRS .................................................................................................................... V

TABLE OF CONTENTS .............................................................................................................. VI LIST OF FIGURES ..................................................................................................................... VII LIST OF TABLES ....................................................................................................................... VII

1.0 INTRODUCTION

1.1 Purpose

1.2 Scope

1.3 Applicable and Reference Documents

1.3.1 Reference Documents

1.3.2 Reference Project Documents

2.0 MISSION OVERVIEW

2.1 Mission Statement

2.2 Mission Background

2.3 Mission Objectives

2.4 Mission Implementation

2.4.1 Space Segment

2.4.2 Ground Segment

2.4.3 Launch Segment

3.0 MATRIX OVERVIEW

3.1 Structural / Mechanical Tests

3.1.1 Mass

3.1.1.1 Expected Levels of Test

3.1.1.2 Unit Testing Philosophy

3.1.2 Modal Survey

3.1.2.1 Expected Levels of Test

3.1.2.2 Unit Testing Philosophy

3.1.3 Static Load / Sine Burst

3.1.3.1 Expected Levels of Test

3.1.3.2 Unit Testing Philosophy

3.1.4 Sine Vibration

3.1.4.1 Expected Levels of Test

3.1.4.2 Unit Testing Philosophy

3.1.5 Random Vibration

3.1.5.1 Expected Levels of Test

3.1.5.2 Unit Testing Philosophy

3.1.6 Acoustic

vii

3.1.6.1 Expected Levels of Test

3.1.6.2 Unit Testing Philosophy

3.1.7 Mechanical Shock

3.1.7.1 Expected Levels of Test

3.1.7.2 Unit Testing Philosophy

3.1.8 Deployment Testing – Solar Arrays

3.1.9 Deployment Testing – Non-Solar Arrays

3.1.10 Life Tests

3.1.11 Moments of Inertia

3.1.11.1 Expected Levels of Test

3.1.11.2 Unit Testing Philosophy

3.2 EMI / EMC Tests

3.2.1 Expected Levels of Test

3.2.2 Unit Testing Philosophy

3.3 Thermal

3.3.1 Thermal Vacuum

3.3.1.1 Expected Levels of Test

3.3.1.2 Unit Testing Philosophy

3.3.2 Thermal Balance

3.3.2.1 Expected Levels of Test

3.3.3 Bakeout

3.3.3.1 Expected Levels of Test

3.3.3.2 Unit Testing Philosophy

3.4 Propulsion Tests

3.4.1 Structural Mechanical

3.4.2 EMI/EMC

3.4.3 Thermal

3.4.4 Propulsion Unique Tests

ABBREVIATIONS AND ACRONYMS

DEFINITIONS

List of Figures Figure 2.4-1 Landsat Next Operations Concept

List of Tables

Table 3.1-1 Structural / Mechanical Environmental Test Matrix Table 3.1-2 Environmental Test Matrix (ETM) Legend Table 3.2-1 EMI/EMC Environmental Test Matrix Table 3.3-1 Thermal and Other Environmental Test Matrix Table 3.4.1-1 Propulsion Mechanical / Structural Environmental Test Matrix Table 3.4.3-1 Propulsion Thermal Environmental Test Matrix Table 3.4.3-2 Propulsion Thermal Testing Legend Table 3.4.4-1 Propulsion Unique Tests Environmental Test Matrix

1.0 INTRODUCTION

1.1 PURPOSE

THIS IS NOT A REQUIREMENTS DOCUMENT.

This is a reference document for the Landsat Next (LNext) spacecraft (SC) procurement. It provides a nominal environmental test matrix for LNext that is compliant with the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 from the LNext Project’s perspective. The purpose is to provide a nominal test matrix to be referenced by vendors when proposing for the LNext SC and Dispenser.

1.2 SCOPE

This description document covers a nominal environmental test matrix along with details about each test or configuration for each test. The rationale or purpose of the test is provided for clarity where appropriate.

This is not a requirements document. Vendors will be required to submit, for approval, their own compliance test matrices per the contract that match their own integration and test (I&T) and verification campaigns.

This document does not address the ETM for LandIS nor any Government Furnished Equipment (GFE) prior to their delivery to the observatory for integration. It does address observatory and mission payload testing.

1.3 APPLICABLE AND REFERENCE DOCUMENTS

1.3.1 Reference Documents

Document Number Title Revision NASA-STD-8719.24 NASA Expendable Launch Vehicle Payload

Safety Requirements A

NPR 7120.5 NASA Space Flight Program and Project Management Requirements

F w/Change 2

NPR 7123.1 NASA Systems Engineering Processes and Requirements

D w/Change 2

GPR 7123.1 Systems Engineering C GSFC-STD-1000 Rules for the Design, Development, Verification, and Operation of Flight Systems H

GSFC-STD-7000 General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects

B

ANSI/AIAA S-080A-2018 Space Systems - Metallic Pressure Vessels, Pressurized Structures, and Pressure Components

ANSI/AIAA S-081B-2018 Space Systems - Composite Overwrapped Pressure Vessels

ANSI/AIAA S-120A-2015 Mass Properties Control for Space Systems 2019 MIL-STD-461 Requirements for the Control of Electromagnetic

Interference Characteristics of Subsystems and Equipment

G

SMC-S-016 Test Requirements for Launch, Upper-stage and Space Vehicles

Document Number Title Revision SMC-S-008 Electromagnetic Compatability Requirements for Space Equipment and Systems

In this document, citations are assumed to be the latest version unless otherwise noted.

This document table was generated from the Landsat Next Common Reference and Applicable Documents List (LNEXT-MGMT-DESC-0008) DRAFT Rev E.

1.3.2 Reference Project Documents

Document Number Title LNEXT-SYS-DESC-0003 Landsat Next Analytical Math Model Definitions

(LAMMD)

LNEXT-SYS-REQ-0005 Landsat Next Environmental Requirements Document

(LNERD)

In this document, citations are assumed to be the latest version unless otherwise noted.

This document table was generated from the Landsat Next Common Reference and Applicable Documents List (LNEXT-MGMT-DESC-0008) DRAFT Rev E.

2.0 MISSION OVERVIEW

2.1 MISSION STATEMENT

Landsat Next, consistent with United States (U.S.) law and government policy, will continue the Landsat program's acquisition, archival, and distribution of multi-spectral imagery affording global, synoptic, and repetitive coverage of the Earth's land surfaces at a scale where natural and human-induced changes can be detected, differentiated, characterized, and monitored over time.

2.2 MISSION BACKGROUND

Following the successful launch of Landsat 8 (formally named Landsat Data Continuity Mission, LDCM) in February 2013, and during the development of Landsat 9, the United States Geological Survey (USGS) and National Aeronautics and Space Administration (NASA) recognized the need to assemble a team of experts from within both agencies to evaluate how to inform an acquisition strategy for the Landsat mission to follow Landsat 9. The NASA-USGS Joint Agency Sustainable Land Imaging (SLI) Architecture Study Team (AST) was formed in September 2018 and was tasked with investigating how to best satisfy the diverse set of user needs collected in the USGS “User Needs for the Sustainable Land Imaging Program – Release 2.0.” These investigations resulted in a set of recommendations to the headquarters of both agencies, delivered in December 2019. The highest-recommended “Roadmap 1” architecture described a small constellation of “superspectral” space-based sensors that would substantially improve the spectral, spatial, and temporal capabilities of previous Landsat missions, while continuing to satisfy the primary goal of ensuring a highly calibrated data set that maintains compatibility with the legacy data of the Earth’s land mass held in the National Satellite Land Remote Sensing Data Archive (NSLRSDA) at USGS’s Earth Resources and Observation Science (EROS) Center. In April 2020 NASA/Goddard Space Flight Center (GSFC) received authorization to initiate the Landsat Next project consistent with the AST’s Roadmap 1 recommendation.

The goal of Landsat Next is to continue the acquisition, archival, and distribution of multi-spectral imagery affording global, synoptic, and repetitive coverage of the Earth's land surfaces at a scale where natural and human-induced changes can be detected, differentiated, characterized, and monitored over time. This goal is in keeping with the Landsat programmatic goals stated in both the Commercial Space Act of 1998 (Public Law 105-303) and the Land Remote Sensing Policy Act of 1992 (Public Law 102-555). This policy requires that the Landsat Program provide data into the future that is sufficiently consistent with previous Landsat data to allow the detection and quantitative characterization of changes in or on the land surface of the globe.

Landsat Next continues the long-running partnership of NASA and USGS, with NASA providing the space and launch segments and USGS providing the ground system, providing the longest continuous global record of the Earth’s surface. The Landsat series of satellites have continuously acquired multispectral images of the global land surface since the launch of the Earth Resources Technology Satellite (ERTS, later renamed Landsat 1) in 1972. The Landsat data archive constitutes the longest continuous moderate-resolution record of the global land surface as viewed from space.

2.3 MISSION OBJECTIVES

Landsat Next has these major mission objectives:

• Collect and archive moderate resolution, Visible Through Short Wave Infrared (VSWIR) reflective and Thermal Infrared (TIR) emissive image data affording seasonal coverage of the global landmass for a continuous period of not less than five (5) years.

• Ensure that Landsat Next data are sufficiently consistent with data from the earlier Landsat missions in terms of relative acquisition geometry, calibration, coverage characteristics, spectral characteristics, output product quality, and data availability to permit studies and management of land cover along with land and water resource change over multi-decadal time periods.

• Ensure Landsat Next is responsive to critical emerging user needs and applications as characterized by periodic assessment, currently the User Needs for the Sustainable Land Imaging Program July 2018, Release 2.0, and identified by the operational requirements for collection, processing, archiving, and distribution of land surface data to the United States Government and other users.

• Distribute Landsat Next data products to the public on a nondiscriminatory basis.

2.4 MISSION IMPLEMENTATION

NASA and USGS each have specific responsibilities for Landsat Next and will deliver the major elements to the overall mission. NASA will provide the Space and Launch Segments of Landsat Next, and USGS will provide the Ground System and mission operations. NASA/GSFC will provide overall Landsat Next project management, mission system engineering, and mission assurance during development and will transition the mission to USGS following on-orbit commissioning.

The Landsat Next post-launch nominal mission operations concept is shown graphically in the Figure below.

Figure 2.4-1 Landsat Next Operations Concept

(Generated from Landsat Next Common Mission Architecture Diagram LNEXT-SYS-DESC-0022 Rev -)

2.4.1 Space Segment

NASA/GSFC will provide the Space Segment, which will consist of a constellation of three observatories flying in coordinated sun-synchronous orbits at 653km altitude, each with nominally identical spacecraft and instrument suites. The observatories will be equally spaced in the orbit, providing in aggregate a six-day ground repeat period at the equator.

The instrument suites will each provide 26 spectral bands with a maximum ground sampling distance of 10m-60m dependent on the spectral band, covering a swath on the ground of approximately 164km on a ground track defined by a world-wide reference system known as

WRS-3.

2.4.2 Ground Segment

The Landsat Ground Segment currently supports mission operations for Landsats 8 and 9.

Landsat Next takes advantage of developments on these missions and will upgrade and expand the current systems to accommodate Landsat Next. The Landsat Ground Segment consists of the Ground System (GS) and its external interfaces, including NASA institutional services. The GS includes the Mission Operations Center (MOC), the Ground Network (GN), and the Data Processing and Archive System (DPAS). External interfaces include NASA's Near Space Network (NSN) and Advanced Communications Capabilities for Exploration and Science Systems (ACCESS), GSFC Conjunction Assessment and Risk Analysis (CARA) and its Flight Dynamics Facility, along with other external interfaces.

The MOC provides the primary means to control and monitor the Landsat Next constellation.

The Landsat Next Flight Operations Team (FOT) at the MOC performs mission planning and scheduling, command and control, health and status monitoring, orbit and attitude maintenance, performance analysis, onboard memory management, and flight and ground software maintenance. The FOT utilizes MOC functionality to detect, investigate and resolve spacecraft anomalies and monitor the instrument image collections from the onboard constellation and generate special image collections. The MOC ingests, processes and archives data via the GN.

The GN includes geographically dispersed ground station resources for mission execution and includes both the Landsat Ground Network (LGN) and a wideband data routing capability, which transfers mission data to DPAS across wide area networks. The LGN provides communication capability for each observatory of the constellation for commanding and housekeeping data via the S-Band and will receive mission data from each observatory over a Ka-band downlink.

The DPAS ingests mission data from the GN, processes the mission data to form data products, and archives the data products (Level 0, Level 1R, Level 1Gs, Level 1T). The DPAS also provides a long-term archive capability for raw data and allows the user community to query, download, and directly interact in the cloud with Landsat Next data products, via a public-facing web portal for receiving data products. The DPAS is located at USGS Earth Resources Observation and Science (EROS) near Sioux Falls, South Dakota.

The USGS will lead overall Landsat Next GS development. The USGS will also lead integration of the GS and ensure timely completion of ground readiness testing in preparation for NASA-led mission readiness activities. The MOC will perform planning, scheduling, and observatory operations activities during Landsat Next mission readiness testing.

2.4.3 Launch Segment

The Launch Segment will provide the assets and services associated with the Launch Vehicle (LV) and the constellation-to-LV integration. This will include the LV; all Launch Vehicle- Ground Support Equipment (LV-GSE), property, and facilities to integrate the constellation to the LV and verify their integration; and prelaunch testing with ground-based functions. The launch vehicle and launch site are TBD. The three observatories comprising the Landsat Next constellation will be launched together on the same launch vehicle.

Sections 2.0-2.4.3 were generated using Landsat Next Common Boilerplate (LNEXT-MGMT- DESC-0005) Rev C

3.0 MATRIX OVERVIEW

The LNext Reference Environmental Test Matrix (ETM) is broken down into four sections:

Structural/Mechanical, ElectroMagnetic Interference / ElectroMagnetic Compatibility (EMI/EMC), Thermal, and a special Propulsion section. The matrix identifies the tests expected for each of the sections and provides details about expected tests.

The project has taken a nominal mission design of the LNext mission payload (dispenser plus three observatories) and deconstructed the mission payload into dispenser, observatory, spacecraft, primary structure, deployable systems, mechanism, components, and propulsion components. . Since the mission payload has three observatories, the test matrix identifies the testing required for the first build article and for subsequent builds of the flight hardware. For certain items, if a qualification unit (non-flight) was built, then the three flight articles would be considered subsequent articles.

The LNext Project (and NASA Center) have received multiple questions about using Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 instead of GEVS for the qualification requirements. As a Center, GSFC requires the use of GEVS per GPR 7123.1 (R- 51), which is given authority by NPR 7120.5 and NPR 7123.1 for flight projects. SMC is used by Launch Services Program (LSP) and the test ranges as the environmental requirements specification for launch vehicles and for space vehicles, alike. LNext took the action to compare and contrast the two specifications to understand the risk associated with using Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 for environmental qualification. LNext looked at flowing Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 to new builds and if units were previously qualified per SMC-S-0016. Our results are as follows:

• Mechanical unit level testing

• Mechanical Overview: Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 follows a qual/acceptance approach and the required test approach is more severe than what is required in GEVS. This is because testing under Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 is typically done on dedicated qualification hardware and increased test amplitudes (+6dB) and durations (3mins) are used to demonstrate life capability for multiple acceptance tests of flight items. The GEVS/NASA verification approach baselines a protoflight approach, where qualification is performed on flight hardware.

• Sine Vibe: Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 does not require sine vibe or any dynamic testing for the low-frequency launch environment. If hardware is qualified under Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 for NASA missions, then it would need to be evaluated for sensitivity to the low-frequency launch environment. If the item has modes below 100 Hz and has mechanisms, then LNext would want to see sine vibe testing to screen for functional failure modes due to dynamic response.

• Composite and Bonded Structures: GEVS requires that all flight composite and bonded structure be proof tested to 1.25 x limit load regardless of prior qualification status. Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 allows for previously qualified composite or bonded structure to be proof tested to 1.1 x limit load. If the hardware being flown has composite or bonded structure, we would want to ensure that these items have been qualified to 1.25 times limit prior to integration with the spacecraft. This is particular important for units and subsystems that will mount to a Goddard spacecraft as the integrated system will undergo sine vibe testing and the structural loads will be limited to 1.25 time launch loads.

• Heritage Hardware: At the unit level, if the unit does not use composite structural components, nor does it have low modes (<100 Hz), then a unit qualified under Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 may be acceptable to LNext. For any heritage hardware, Section 2.2.3 of the LNERD would still apply. At the Observatory or Instrument level, verification to the LNERD would still be required to address the three bulleted concerns above.

• Thermal

• Thermal Overview: The thermal testing in Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 requires more testing, at wider test temperatures, and adds risk to the program costs. The Project finds that using Test Requirements for Launch, Upper-stage and Space Vehicles, SMC- S-016 for procurement of units could be acceptable (qualification by heritage

– reference LNERD Section 2.2.3) However, GEVS is still the recommendation for instrument level and observatory level testing.

• Unit Level Proto-Qualification: Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 requires up to 5C margin above 11C model uncertainty for unit level qualification. This results in a minimum test rage of -29C to 66C for unit qualification testing. This is well above typical test ranges (-20C to 50C) when GEVS is applied and is a concern for standard commercial electronics like wheels or star trackers.

• Observatory/Instrument Level Proto-Qualification: Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 requires 8 hr soaks on the last thermal cycle where GEVS requires 24 hours. GEVS also requires a total of 12 cycles where Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 is less clear.

• EMI/EMC

• In all sections addressing EMI/EMC, Test Requirements for Launch, Upper-stage and Space Vehicles, SMC-S-016 refers to Electromagnetic Compatability Requirements for Space Equipment and Systems, SMC-S-008, which provides the substantive details for these requirements and tests.

• Electromagnetic Compatability Requirements for Space Equipment and Systems, SMC-S-008 specifies a significant number of tests beyond those specified in GEVS. Our assessment at GSFC is that these additional tests would add significant scope, risk, and cost to the test program while adding no tangible benefits.

• General Overview: Any claims of qualification via Electromagnetic Compatability Requirements for Space Equipment and Systems, SMC-S-008 requires a full assessment of the testing performed against the LNERD.

Therefore, the matrix provided in this document follows the LNERD.

3.1 STRUCTURAL / MECHANICAL TESTS

Table 3.1-1, below, is the structural / mechanical environmental test matrix for LNext. Table 3.1- 2 is the matrix legend.

The below matrix is a nominal test program that does not account for any schedule or cost efficiencies that vendors may propose.

Specifying that the baseline of an acoustic test of the mission payload may require a vendor to include acoustic testing prior to some observatory-level thermal vacuum testing is complete on subsequent units is an example of the nominal program. While the preferred order of testing is electrical, mechanical, thermal, per section 2.2.1 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005, the LNERD also states that” no specific environmental test sequence is required.”

If a different approach from the standard is recommended, care must be taken to properly instrument the test article and ensure prior testing has not been exceeded. In the case of mission payload acoustic test, it would be expected that the observatory primary structure and components with lower margins of safety would determine whether the acoustic test exceeded lower-level qualifications.

Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 Section 2.2.3 addresses qualification of hardware by similarity. That section does not contradict this document or the ability of a vendor to propose most components / electronics as qualified hardware. The comparison details must be approved by the Landsat Project. Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005, Section 2.2.3 provides minimum areas of review.

Table 3.1-1 Structural / Mechanical Environmental Test Matrix.

Table 3.1-2 Environmental Test Matrix (ETM) Legend

Legend Description Q Qualification Test Levels PF Proto-flight Test Levels AT Acceptance Test Levels (or workmanship)

PF/AT Proto-flight Test Levels or Acceptance based on design QS Qualification by Similarity M Test with measured results (mass, grounding, etc.)

T Planned test where Q, PF, or AT do not apply

LT Life Test (Life duration) AN Analysis TT Time and Temp Bakeout

QCM Bakeout with TQCM DP Deployment, Full deploy / Pop & Catch / First motion, G-negated HC Hot / Cold functional tests. Usually @ ambient pressure PQ Proto-Qualification Test

3.1.1 Mass

Mass should be measured or weighed down to the piece part-level, when possible.

Mass should be reported at the component level and rolled up to the mission-payload level.

The vendor should track and report mass growth allowance per Mass Properties Control for Space Systems, ANSI/AIAA S-120A-2015 or internal company standards. The vendor should also track and report margin against the vendor allowable mass (not GSFC-STD-1000, Goddard Open Learning Design (GOLD) Rules, Rule 1.06).

The accuracy of the rolled up final mass should be within +/- 0.2%.

Reference Section 2.4.7 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.7 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.1.1 Expected Levels of Test

Mass should be weighed and tracked to the piece part level. Consumables like epoxy, grease, tape, etc. should be weighed with a best effort.

3.1.1.2 Unit Testing Philosophy

Testing should be conducted at the following levels, at a minimum:

• Mission payload

• Dispenser

• Observatory (3x)

• First article and subsequent articles

3.1.2 Modal Survey

The vendor should test-verify and report all modes under 70 Hz. The final frequency range for correlation will be derived from Launch Vehicle Interface Requirements Document (IRD). For simple mode shapes, the vendor may be able to verify structural modes via sine sweep testing vs modal survey.

The results should be used to correlate the mission payload math model for coupled loads analysis with launch vehicle (LV). Cross-orthogonality checks of the test and analytical mode shapes, with respect to the analytical mass matrix, should be performed with the goal of obtaining at least 0.9 on the diagonal and no greater than 0.1 off-diagonal. (Reference the Landsat Next Analytical Math Model Definitions (LAMMD), LNEXT-SYS-DESC-0003).

Frequencies between the corresponding test and analytical modes should match within 5%.

Reference Section 2.4.1.2 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.1.2 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.2.1 Expected Levels of Test

The following are the expected level of test:

• Dispenser (with mass simulators for the observatories)

• Spacecraft bus structure (with mass simulators for components and for LandIS)

• Deployable assemblies (solar array assembly, high-gain antenna (HGA) boom) on a case-by-case basis

3.1.2.2 Unit Testing Philosophy

Testing should be conducted at the following levels, at a minimum:

• Expected for first article

• Can use sine sweeps to verify subsequent builds match frequencies from modal of first / representative test article

3.1.3 Static Load / Sine Burst

This test is intended to be used on primary and secondary structural elements. The Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 requirement to achieve a test factor of 1.25 times limit load for qualification only applies to mechanically induced loading from launch and on-orbit operations.

The strength qualification test must be shown to produce forces equal to 1.25 times limit at structural interfaces as well as in structural elements which have been shown to have the lowest margins for all identified failure modes of the hardware. This could be accomplished via sine vibration with augmented levels or via no-test factors of safety (Fsy=2.0, Fsu=2.6 for metallic structure only). Strength qualification using sine vibration or no-test factors of safety requires project approval.

The strength qualification test must be accompanied by a stress analysis that demonstrates positive margins using the appropriate factors of safety.

Beryllium, nonmetallic-composite, and metallic-honeycomb structural elements (both primary and secondary), and bonded structural joints require a proof test to 1.25 x the limit load, regardless of if there is a qualified first article. Metallic honeycomb can use appropriate process controls and coupon testing to satisfy proof test requirements for previously qualified structures.

Reference Section 2.4.1.3 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.1.3 thru 2.4.1.5 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.3.1 Expected Levels of Test

The following are the expected level of test:

• Dispenser (with mass simulators for the observatories)

• Spacecraft bus structure (with mass simulators for components and for LandIS)

• Deployable assemblies (solar array assembly, HGA boom) on a case-by-case basis

• Components

3.1.3.2 Unit Testing Philosophy

Testing should be conducted at the following levels, at a minimum:

• Proto-flight test levels (PF) first article

• Qualification by similarity for metallic structure

• Proof subsequent builds if beryllium, composite, or bonded joints

3.1.4 Sine Vibration

Sine testing is typically run over the 5-50 Hz range, with analysis used over the range 50-100 Hz.

Testing is allowed over the full range, however. The vendor can augment test levels to cover strength qualification for a structure where applicable (requires GSFC approval).

Test input may be notched to keep interface loads from exceeding strength qualification levels with prior approval.

The test articles should be in flight configurations / states (unpowered or powered and monitored).

Reference Section 2.4.3 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.3 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.4.1 Expected Levels of Test

The following are the expected level of test:

• Dispenser (with mass simulators for the observatories)

• Fully integrated flight observatories

• Mechanisms

• Subsystems and components with modes below 75 Hz

3.1.4.2 Unit Testing Philosophy

Testing should be conducted at the following levels, at a minimum:

• PF for first build of all articles

• Can use AT for follow on units, provided any orientation issue is addressed

3.1.5 Random Vibration

Random vibration is derived from the acoustic impingement of the mission payload from the launch environment. Random vibration is also used as a minimum workmanship test for screening components.

Notching for sensitive components (optics, etc.) is allowed with prior approval.

The test articles should be in flight configurations / states (unpowered or powered and monitored).

Reference Sections 2.4.2.3 thru 2.4.2.5 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Sections 2.4.2.3 thru 2.4.2.5 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC- STD-7000 for more details.

3.1.5.1 Expected Levels of Test

The following are the expected level of test:

• Box level (component) - test levels must envelope GEVS minimum workmanship levels for both protoflight and acceptance level tests

• Stowed solar array – random or acoustic to verify vibro-acoustic requirements depending on assessment

• Observatory – Either random or acoustic depending on assessment

• Not expected at the mission payload level (Expecting an acoustic test) (Verification should be covered by acoustic testing)

3.1.5.2 Unit Testing Philosophy

Testing should be conducted at the following levels, at a minimum:

• PF for first build of all articles

• Can use AT for follow on units, provided any orientation issue is addressed

3.1.6 Acoustic

This test verifies the hardware for its expected vibroacoustic environment.

An acoustic test is expected at the mission payload level, given the large flat panels at the observatory level plus the close proximity of the observatories to each other on the dispenser.

An acoustic test is also expected on the stowed solar array wing, including interface mounts (flight-like).

The test articles should be in flight configurations / states (unpowered or powered and monitored).

In a clarification to the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005, this mechanical test can be performed after thermal vacuum testing (TVac). However, the test article MUST be instrumented to show prior testing levels are not exceeded, which could invalidate any completed thermal testing.

The vendor may provide analysis at lower levels of assembly to show article is not sensitive to acoustics. (Verification would then be covered by random vibration testing.)

Reference Section 2.4.2.2 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.2.2 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.6.1 Expected Levels of Test

The following are the expected level of test:

• Mission payload (dispenser with 3x observatories)

• Observatory – Either random or acoustic required to satisfy vibro-acoustic verification depending on assessment.

• Stowed solar array and any other large flat paneled surface

3.1.6.2 Unit Testing Philosophy

Testing should be conducted at the following levels, at a minimum:

• PF levels for first build of all articles including Mission Payload

• AT for follow-on units

• Minimum acoustic test level is 138 dB for both AT and PF

3.1.7 Mechanical Shock

The project expectation is that the mechanical shock tests use actual devices for testing. The test program should include two firings of all dominant shock producing devices required for qualification of the test article(s). All on-board shock sources must be actuated to pass verification.

The test articles should be in flight configurations / states (unpowered or powered and monitored).

If the vendor proposes to defer shock testing to a higher level of assembly (like observatory level), an initial analysis or assessment against shock load should be provided before deferral can be approved.

All components identified as shock sensitive must show qualification to 1.4x limit level (+3dB over max predicted environment). Shock testing may be performed below the component level of assembly to demonstrate qualification for shock sensitive items, if needed.

Reference Section 2.4.4 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.4 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.7.1 Expected Levels of Test

The following are the expected level of test:

• Observatories at the dispenser interface (separation systems - 2x interfaces – Tilt and deployment)

• Observatories at the solar array interface (plus other deployable, 2x firings as required for qualification)

• Observatories at the LandIS interfaces; (internal LandIS shock sources, if applicable)

3.1.7.2 Unit Testing Philosophy

Testing should be conducted at the following levels, at a minimum:

• Baseline is that the actual device will be used for all mechanical shock for all testing

• Component shock test deferral requires assessment and may require simulated shock testing to demonstrate margin for shock sensitive hardware

• Two actuations required for qualification if using actual devices

3.1.8 Deployment Testing – Solar Arrays

Solar array components are given the same low-level tests as boom components, then at the array level would typically see an acoustic proto-flight qualification test along with vibe and thermal cycling while stowed.

Both first motion and full deploy testing in a g-negation system are required at the subassembly level in an ambient environment.

Subsequent array builds would similarly be released and deployed after acceptance-level environment testing.

Typically, all solar arrays are given a quick functional test (first motion or pop and catch, g-negated) after mechanical environments at the observatory level, including shock. They are then detached and given a full-motion test (g-negated) at the array level. Later solar arrays are remounted and given a final first-motion test (end-to-end). Deployed solar arrays tracking range of motion should be assessed for Observatory physical and field of view interferences.

Arrays or large deployable assemblies may be shipped separate to the launch site. If they are shipped separately, there is typically a quick functional test (first-motion) after they are installed at the launch site.

If the arrays are shipped installed, a quick functional test could still be required. Determination of the necessity of this test will depend on the transportation loads seen during shipment. A “ship and shoot” approach may also be acceptable (no first-motion at the launch site).

Reference Section 2.4.5 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.5 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.9 Deployment Testing – Non-Solar Arrays

One-time deployables like doors, booms, and masts require functional tests at the component level (hinge spring, damper, restraint/release devices) usually at low/high temps (often done at the vendor, not in vacuum, but after a random vibe test, at a minimum).

One-time deployables are given a functional test at the subassembly level in ambient before bus integration, typically g-negated after seeing launch/on-orbit environments.

Finally, the deployable assemblies have an initial and final functional (first-motion at least) test at the observatory level before/after all environments (in ambient, without detachment from the bus, to verify end-to-end release success).

Initial deployments on the bus are also typically given a full deployment (verify free-range-of-motion) to ensure there is no interference at the top assembly from multi-layer insulation (MLI) or any other closely mounted hardware.

Ideally, both hot and cold functional tests are required for qualification of the first deployable subassembly and for verification of torque margin.

Simple acceptance tests in ambient conditions would be required for subsequent subassemblies.

Generally, functional testing of subsequent subassemblies would not be deferred.

Philosophically, all deployables are required to be functionally tested, while attached in observatory thermal vacuum (TVAC), at low/high temps, however, exceptions can be made for larger deployables such as solar arrays and booms, recognizing access/chamber geometry limitations.

Reference Section 2.4.5 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.5 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.10 Life Tests

Typically, a life test unit (LTU) is a flight spare or qualification unit, but in general, is fabricated simultaneously as flight units with the appropriate certification logs.

LTUs should go thru an PF or AT environmental test program prior to the start of the life test.

The test program should simulate the environmental testing and launch cycles that the hardware will see prior to its operational cycles LTU set up should consider the effects of gravity and external loading, at a minimum.

During the test, thermal environments should also be representative of flight. If there are significant bulk temperature changes on orbit, the LTU should also have multiple temperature transitions.

The effects of vacuum on the unit should also be considered.

Nominal voltages are used during the test, if applicable.

The goal is 2x the number of cycles in the unit life cycle, including ground testing.

There should be time to break down and inspect the LTU after testing, with adequate time to react to any discoveries from the life test.

General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 has a long section detailing the test philosophy of life test units that helps explain the complexity of the test. This section provided some highlights on areas where the project sees poor execution and planning of LTUs.

Reference Section 2.4.5.1 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.5.1 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.11 Moments of Inertia

Weight, center of gravity, and moment of inertia are used in predicting mission payload performance during launch, insertion into orbit, and orbital operations. The parameters are determined for all of these configurations to evaluate flight performance in accordance with mission requirements.

For LNext, mass properties are verified by analysis and/or measurement.

Regardless of the verification method (T or A), the tolerances of the mass properties are:

Center of gravity: ± 0.15 cm (± 0.06 in.)

Moments of inertia: ± 1.5%

Reference Section 2.4.7 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005 or Section 2.4.7 of the General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 for more details.

3.1.11.1 Expected Levels of Test

Reporting should be at the observatory level and with multiple configurations. Below are a few of the expected configurations to be provided:

• Stowed (launch)

• Deployed (array, et al.)

• Full, half, and near empty tanks

• Array in multiple orientations (usually every 90 degrees)

• HGA boom at extreme fields of regard (FOR), or as appropriate

• Any other impacts to inertias

3.1.11.2 Unit Testing Philosophy

Testing should be conducted at the following levels, at a minimum:

• Mass properties are required to be measured or calculate for each observatory.

3.2 EMI / EMC TESTS

The lowest level of EMI/EMC testing is typically performed at unit/component (electronics box) level. However, testing may be deferred to subsystem level, where one or more components form an integrated subsystem that will be tested together. Testing at lower levels of assembly (e.g., board level) may be performed as a risk reduction measure but are not required. The suite of EMI/EMC testing to be performed is dependent upon the function of the component/subsystem electronics and its power interface and is specified as such in Table 2.5.1.1-1 EMC Requirements Applicability of Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-

REQ-0005.

Table 3.2-1 below is the EMI/EMC environmental test matrix for LNext. Table 3.1-2 is still the applicable legend for the matrix. First article components/subsystems receive the full suite of EMI/EMC testing applicable, based on LNERD Table 2.5.1.1-1. For subsequent articles CS114 and RS103 are not required, so long as the first article passes these tests and subsequent articles are identical and manufactures to the same standards, processes, and procedures. Further, subsequent articles may be tested over a reduced frequency range for RE102, sufficient to envelop observatory and launch vehicle receiver frequencies and demonstrate in-family emission as compared with first article results. First article test results may also be used to evaluate the opportunity and efficacy of reducing the necessary RE102 antenna polarizations and positions required for subsequent article testing. The goal is to characterize the worst cases of those test configurations, based on first article results. Consideration should also be given to the geometric positioning of the unit under test (UUT) when mounted for flight, relative to other flight systems that may be affected by radiated emissions.

There is no specific EMI/EMC testing required at the spacecraft level, as verification is deferred to observatory level. Spacecraft level risk reduction testing may be performed if a particular concern is identified and there is a desire to retire the risk.

There are no quantitative conducted emissions or conducted susceptibility tests at observatory level, other than power quality measurements of the electrical power system (EPS) Main Bus.

The power quality measurements include inrush measurements performed for individual loads, as they are integrated to the EPS Main Bus, and the Power Profile test performed after all loads have been integrated. The first observatory is fully tested for aggregate radiated emissions (RE) and aggregate radiated susceptibility (RS). System-level radiated tests are not to be considered "repeats" of RE102 and RS103 performed at unit/subsystem level. RE102 and RS103 are defined as unit/subsystem level tests, and that nomenclature will not be used at system level. Subsequent observatories are not required to have aggregate RS testing performed (unless significant susceptibilities are discovered on the first article) and may implement a reduced set of aggregate RE testing. Following a similar approach used for RE102 testing for components/subsystems, observatory aggregate RE may be performed with reduced frequency range and antenna polarization/position, depending on results from the first observatory. The philosophy in determining frequency range and antenna configurations is similar to that used for components and subsystems, including determining relative position of potential RE victims. All observatories are required to pass an EMI/EMC radio frequency (RF) self-compatibility test.

Dispenser EMI/EMC testing will be determined based upon the design of the dispenser, launch configuration of the observatories and mission payload processing at the launch site. The first consideration in determining the dispenser EMI/EMC test suite is to satisfy range safety concerns; namely to ensure sufficient margin to prevent inadvertent, premature deployment of observatories and to ensure that any dispenser EMI does not compromise launch vehicle avionics. Other considerations include ensuring compatibility between dispenser and observatories for launch configuration and planned mission payload testing on-stand.

As observatories and dispenser will each undergo system level EMI/EMC testing intended to ensure compatibility with each other and with the launch vehicle, the only mission payload level testing required is a self-compatibility test. This is essentially a confidence and validation test that demonstrates that system level verification test results are valid.

Per Section 2.5 of the Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS-REQ-0005, the EMI/EMC requirements are based on General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects, GSFC-STD-7000 and Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment, MIL-STD-461 Revision G and are tailorable.

Section 2.5.1.1 details the applicability of the testing on hardware plus guidance of tailoring.

Table 3.2-1 EMI/EMC Environmental Test Matrix

3.2.1 Expected Levels of Test

The following are the expected level of test:

• Electronic box / Unit/ Subsystem level:

• Full EMI/EMC suite for first article (Qual)

• Reduced suite for subsequent articles (Acceptance)

• System/ Observatory level:

• Inrush, power quality, Self Compat, Aggregate RE/RS are required for the first article

• Subsequent articles do not need aggregate RS

• Mission payload:

• Self-Compatibility

3.2.2 Unit Testing Philosophy

Testing should be conducted at the following levels, at a minimum.:

• Units, Components, or Interconnected Subsystems:

• The full EMI suite will occur on all first article (as applicable, per Landsat Next Environmental Requirements Document (LNERD), LNEXT-SYS- REQ-0005 Table 2.5.1.1-1):

• CE101, CE102/CE103, CMBCE, Turn-on Transient (GEVS Conducted Emissions, Time Domain, Transients), CS101, CE106, RE102, CS114, RS103, CS103, CS104

• Subsequent Articles:

• CE101, CE102/CE103, CMBCE, Turn-on Transient (GEVS Conducted Emissions, Time Domain, Transients), CS101, CE106, RE102 (reduced frequency range, polarity and positions)

• Note: CE106, CS103, and CS104 are specific tests for antenna-connected RF…