Attachment F - LandIS IRD.pdf

DOORS EXPORT

National Aeronautics and Space Administration

Goddard Space Flight Center Greenbelt, Maryland

LNEXT-LANDIS-ICD-0001, Revision - Landsat Next, Code 426

Landsat Instrument Suite (LandIS) Interface Requirements Document (IRD) dsierfel LNext CM Stamp

LNEXT-LANDIS-ICD-0001

Revision -ii

Landsat Instrument Suite (LandIS) Interface Requirements Document (IRD)

Prepared by:

Electronic Signature in TDMS

12/15/2022 Leslye Boyce Date Landsat Next Deputy Mission Systems Engineer

NASA/GSFC, Code 426

Approved by:

Wen-Ting Hsieh Date Landsat Next Payload Manager

Mark Edison Date Landsat Next Deputy Observatory Manager

Evan Webb Date Landsat Next Systems Manager NASA/GSFC, Code 599 iii

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

CM Foreword This document is a Landsat Next Project Configuration Management (CM)-controlled document.

Changes to this document require prior approval of the applicable Configuration Control Board (CCB) Chairperson or designee. 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 v

Change History Log Revision Effective Date Description of Changes

- 12/15/2022 LNEXT-CCR-0019 – Initial Release vi

List of TBDs/TBRs 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.

John Satrom/LSS MCDR

TBx-2 Section 3.2.1.2

LandIS shall meet the dimensional envelope constraints of 1.95m (76.77 in) in the +Z by 1.37m (53.94 in) in the +Y axis by 2.0 m (78.74 in) in the X Axis (TBS) under a combination of static, dynamic, and thermal conditions encountered during factory assembly, system test, transportation and handling and launch.

Dan Helfrich/Mechanical ISRR

TBx-3 Section 3.2.1.4

LandIS shall have a total mass of not to exceed 550 kg (TBR) mass including all associated hardware, intra-LandIS harnessing, and any attached external harnessing extending to the spacecraft connector interface bracket.

Dan Helfrich/Mechanical ISRR

TBx-4 Section 3.2.1.4

LandIS center of mass, including IMSC, shall be no more than TBD from the centerline of LandIS volume.

Dan Helfrich/Mechanical ISRR

TBx-5 Section 3.2.1.6

LandIS structural support components shall be designed to show positive margin for limit load using FS=1.25 for yield and FS=1.4 for ultimate, when constituted of MSFC-STD-3029 Table 1 materials. (TBR)

Dan Helfrich/Mechanical ISRR

TBx-6 Section 3.2.1.7

The IMSC volume shall not exceed a Star Tracker Subassembly volume of .18 m^3 (TBR) and a Scalable Inertial Reference Unite (SIRU) Subassembly volume of .12 m^3 (TBR).

Dan Helfrich/Mechanical

SC

SRR

TBx-7 Section 3.2.1.7

LandIS shall accommodate an IMSC total mass not to exceed 50 Kg (TBR) on the LandIS deck.

Dan Helfrich/Mechanical

SC

SRR

vii

TBx Location Summary Ind. Name/Org. Due Date

TBx-8 Section 3.2.1.7

The thermal heat transfer between the LandIS deck and IMSC shall be less than or equal to 0.1 W/C (TBR) over the orbit average.

Deepak Patel/Thermal

SC

SRR

TBx-9 Section 3.2.1.7

LandIS shall provide an unobstructed glint free zenith-directed field of view for the star trackers in the IMSC of 25 deg (TBR) along track by 25 deg (TBR) cross-track.

Dan Helfrich/Mechanical

SC

SRR

TBx-

Section 3.2.2.2

LandIS shall provide an IMSC interface that maintains alignment stability of TBD microradians or less, 3-sigma, per axis, to the IMSC mounting interface, during a period of over 18 days.

Andrew Tritton/ACS SC

SRR

TBx-

Section 3.2.2.2

LandIS shall provide an IMSC interface that maintains alignment stability of TBS microradians or less, per axis, to the IMSC mounting interface, during a period of over 30 seconds.

Andrew Tritton/ACS

SC

SRR

TBx-

Section 3.2.2.3

LandIS shall maintain uncompensated momentum contribution not exceeding +/-

0.5 N-m-sec per axis. (TBR)

Andrew Tritton/ACS

SC

SRR

TBx-

Section 3.2.3.3

The thermal heat transfer between the LandIS deck and the spacecraft shall be less than or equal to 0.1 W/C (TBR) over the orbit average.

Deepak Patel/Thermal

SC

SRR

TBx-

Section 3.2.4.1

LandIS shall receive the following electrical interfaces and services from the spacecraft (TBR), by design.

-LandIS output data bus(es) and input bus(es) -Operational Power Service -Survival Heater Power Service -Grounding Interface -1 Pulse Per Second (PPS) Interface -Discrete commands and telemetry, as needed -Discrete Bilevel & Analog telemetry, as needed

Robert Vernot/ES ISRR

TBx-

Section 3.2.4.2

LandIS shall not exceed orbit average power of 350W (TBR). Anisa Jamil/Power ISRR

TBx-

Section 3.2.4.3.1

LandIS Survival heaters shall be sized using a minimum Main bus voltage of 24 V (TBR) at the spacecraft interface.

Anisa Jamil/Power ISRR

TBx-

Section 3.2.5.1

The LandIS shall provide LandIS imaging sensor data via an output data bus at a minimum rate no less than TBS.

Richard Covington/CDH ISRR viii

TBx Location Summary Ind. Name/Org. Due Date

TBx-

Section 3.2.5.1

LandIS shall provide a limited amount (TBD) of LandIS FPA & test pattern data and raw detector diagnostic data to the spacecraft over an output data bus.

Richard Covington/CDH ISRR

TBx-

Section 3.2.5.1

LandIS shall limit the size of the LandIS imaging sensor data delivered to the SC for storage to no more than 5 seconds per data file. (TBR) Rationale:The 5 seconds of data collection is intended to limit the file size to no more than 2 Gbytes. At worst case, each block of sensor data delivered by the instrument will be<=5 (TBR) seconds of image collection and therefore should not exceed 2 GB, which is well below the 4 GB limit required to comply with the CCSDS encapsulation standard used by the spacecraft. In addition, limiting the duration of imaging contained within a single file limits the impact if a file is lost (a single file will never contain more than 1/5 of a scene)

Richard Covington/CDH ISRR

TBx-

Section 3.2.5.1

LandIS shall provide telemetry as polled by the spacecraft at a frequency of TBS.

Richard Covington/CDH ISRR

TBx-

Section 3.2.5.4.2

LandIS shall provide the "I'm alive" message at a rate of every 1 second (TBR) to the SC as an active bi-level signal.

Richard Covington/CDH ISRR

TBx-

Section 3.2.6

LandIS shall require a near-continuous purge from the arrival at the SC contractor facility until launch (TBD).

Alan Abeel/Contamination ISRR ix

Table of Contents CM FOREWORD ......................................................................................................................... IV

CHANGE HISTORY LOG ............................................................................................................ V

LIST OF TBDS/TBRS .................................................................................................................. VI

TABLE OF CONTENTS .............................................................................................................. IX

LIST OF FIGURES ........................................................................................................................ X

LIST OF TABLES .......................................................................................................................... X

1.0 INTRODUCTION

1.1 Purpose

1.2 Scope

1.3 Related Documents

1.3.1 Reference 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 INTERFACE REQUIREMENTS

3.1 General

3.2 SUBSYSTEM REQUIREMENTS

3.2.1 Mechanical Interface

3.2.1.1 Reference Frames

3.2.1.2 Volume and Dimension

3.2.1.3 LandIS Field of View

3.2.1.4 Mass Properties

3.2.1.5 LandIS Access, Integration & Deintegration

3.2.1.6 LandIS Mounting

3.2.1.7 Instrument Mounted Spacecraft Components (IMSC) Sensor Accommodation

3.2.2 Orbit Control, Pointing and Alignment

3.2.2.1 Pointing Stability and Jitter

3.2.2.2 Alignment

3.2.2.3 Disturbance Torques

3.2.3 Thermal Interface Requirements

3.2.3.1 Operating & Survival Heaters and Temperatures

3.2.3.2 Thermal Allocations

3.2.3.3 Thermal Isolation

3.2.4 Electrical Interface Requirements

x

3.2.4.1 Electrical Interfaces

3.2.4.2 Power Allocation

3.2.4.3 Main Bus Power

3.2.4.4 Power Distribution Interfaces

3.2.4.5 Instrument Suite Class R Grounding Interface

3.2.4.6 Electric Harnesses and Connectors

3.2.5 Command and Data Handling

3.2.5.1 Data Bus(es)

3.2.5.2 Time-of-day Signal

3.2.5.3 Discrete Commands

3.2.5.4 Discrete Telemetry

3.2.6 LandIS Purge and Venting

APPENDIX A ABBREVIATIONS AND ACRONYMS

APPENDIX B DEFINITIONS

List of Figures

Figure 2.4-1 Landsat Next Operations Concept Figure 3.2.1.1-1 Observatory Orbital Reference Frame Figure 3.2.1.2-1 LandIS Triplet Radially Stowed Configuration Figure 3.2.1.6-1 Mass Acceleration Curve Figure 3.2.2.3-1 Torque Limit Figure 3.2.2.3-2 Torque Duration Limit Figure 3.2.5.1-1 LandIS Functional Data Buses

List of Tables

Table 3.2.1.6-1 Component Design Loads (Break Points)

1.0 INTRODUCTION

1.1 PURPOSE

The set of Landsat Next Interface Requirements Documents sets forth the general, interface requirements imposed between the LandIS and the Spacecraft.

1.2 SCOPE

Throughout this document references will be made to the LandIS, the spacecraft and the LandIS.

References to the LandIS refer to the LandIS suite and apply only to the LandIS. References to the "Spacecraft" or "SC" applies only to the Landsat Next spacecraft.

The requirements that are indicated with "Reserved" text are applicable to the interface;

however, they are not allocated directly to that side of the interface.

The Landsat Next Interface Requirements documents (SC IRD, LandIS IRD) are controlled and maintained by the Landsat Next Project office. The SC IRD is levied on the spacecraft contractor. The LandIS IRD is levied on the LandIS contractor. These IRDs are maintained at Level 3 and will contain sibling tracing to tie the SC interface requirements and LandIS interface requirements.

1.3 RELATED DOCUMENTS

1.3.1 Reference Documents

Document Number Title Revision Public Law #105-303 “Commercial Space Act of 1998,” Public Law

#105-303, 112 Stat., 2843., H.R. 1702, 105th Congress, Adopted October 28, 1998

N/A

Public Law #102-555 “Land Remote Sensing Policy Act of 1992,” Public Law #102-555, 106 Stat. 4163., H.R.

6133, 102nd Congress, Adopted October 28, N/A

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

This document table was generated from the Landsat Next Referenced Documents List Draft Rev -

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 multispectral image data and thermal 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 of land cover and land use change over multi-decadal 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 general 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

2.4.1 Space Segment

NASA/GSFC will provide the Space Segment via competitive procurements for the science instruments and the spacecraft bus. The Space Segment 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 NASA ACCESS Space relay (i.e. TDRSS) and government/commercial ground station, NASA/GSFC Conjunction Assessment and Risk Analysis (CARA) and its NASA/GSFC 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 or cloud-based data routing capability to transfer both mission data to DPAS, and TT&C data to the MOC. The LGN consists of US Government-owned, international, and commercial ground stations, and provides communication capability for each observatory of the constellation for commanding and housekeeping data via S-Band two-way links. The LGN will also receive mission data from each observatory via high rate Ka-band downlinks.

The DPAS ingests, processes, and archives LNext mission data from the GN. 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 science 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 B

3.0 INTERFACE REQUIREMENTS

3.1 GENERAL

The LandSat Next Interface Requirements are maintained across two documents; namely the SC IRD and LandIS IRD. They are controlled and maintained by the LandSat Next Project office.

The SC IRD is levied on the spacecraft contractor. The LandIS IRD is levied on the LandIS contractor. These IRDs are maintained at Level 3 and will contain sibling tracing to link the SC interface requirements and LandIS interface requirements. Changes to a requirement with a sibling trace will require review/update of the corresponding sibling requirement and approval of both parties of the interface.

Since the Project is early in the mission, and the LandIS procurement will proceed the Spacecraft procurement, the strategy is to have the LandIS contractor provide an Instrument Interface Description (IDD) Document. The IDD will be used to better inform and update these interface requirements.

For references to specific definitions and terms, refer to the Landsat Next Lexicon.

Throughout this document references will be made to the instrument, the spacecraft and the LandIS. References to the LandIS refer to the LandIS suite and apply only to the LandIS.

References to the "Spacecraft" or LNext SC applies to the LandSat Next spacecraft.

3.2 SUBSYSTEM REQUIREMENTS

3.2.1 Mechanical Interface

3.2.1.1 Reference Frames

The Observatory Orbital Reference Frame is a right-handed, orthogonal, XYZ coordinate system defined such that the origin is at the Observatory center of mass (CM), the +Z axis points toward Geocentric Nadir, the +X axis is coplanar with both the +Z axis and the Observatory inertial velocity vector (and is in the general direction of the Observatory inertial velocity vector), and the +Y axis completes the right-handed, orthogonal coordinate system, as shown in Figure 3.2.1.1-1.

NOTE: See Appendix B Definitions for the Geocentric Nadir definition.

Figure 3.2.1.1-1 Observatory Orbital Reference Frame

LandIS is to use an optical reference coordinate system that is defined as a right-hand, orthogonal, body fixed, XYZ coordinate system with the +Z axis aligned with the LandIS optical axis and the coordinate system documented as shown in Figure 3.2.1.1-1.

LandIS contractor or provider will describe its LandIS Mechanical (or Body) Reference Frame in the LandIS's MID including the mathematical translation between the origin of the LandIS Mechanical Reference Frame and the LandIS Optical Reference Frame.

LandIS Body Frame is a right-hand, orthogonal, body-fixed XYZ system with +Y / +Z plane at the SC to LandIS interface plane, and the +Z direction pointing to nadir, the +X direction in the velocity vector, and the +Y completing the right-handed, orthogonal coordinate system.

3.2.1.2 Volume and Dimension

LIRD-139 LandIS shall meet the dimensional envelope constraints of 1.95m (76.77 in) in the +Z by 1.37m (53.94 in) in the +Y axis by 2.0 m (78.74 in) in the X Axis (TBS) under a combination of static, dynamic, and thermal conditions encountered during factory assembly, system test, transportation and handling and launch.

Rationale: The dimensional envelope constraints include the LandIS deck, IMSC and extends from the length of the flexures to the SC mounting point. A separate on-orbit volume requirement will need to be defined in the IDD if LandIS incorporates a deployable device into its operational configuration. Axes referenced are for the observatory body frame defined in Section 3.2.1.1.

Figure 3.2.1.2-1 LandIS Triplet Radially Stowed Configuration

Note: Requirements are for the stowed configuration as shown in Figure 3.2.1.2-1. The deployed envelope will not obstruct any observatory fields of view.

LIRD-174 LandIS dimensional envelope shall enclose the fully assembled LandIS, LandIS-unique flexures, LandIS-unique fastening hardware, thermal blankets (including billowing during launch and ascent), connectors (LandIS-side only), and intra-instrument harness (with connectors), as well as any other items that constitute any part of a deliverable LandIS along with the IMSC hardware.

Rationale: The intent of this requirement is that everything provided as part of a deliverable instrument, including the items identified above, be allocated against the instrument size and weight allocations, and that everything provided by the spacecraft contractor be held against the spacecraft allocation. The IMSC is to be included in the LandIS physical envelope. Axes referenced are for a stowed configuration and are for the observatory body frame defined in Section 3.2.1.1.

3.2.1.3 LandIS Field of View

LIRD-154 LandIS boresight of the unobstructed field of view shall be parallel to the nadir (+Z) axis.

Rationale: This requirement is intended to formalize the relative orientation of the spacecraft and LandIS coordinate systems - i.e., the LandIS boresight axis is in the spacecraft +Z (nadir) direction. The SC is responsible for alignment control between the Spacecraft Attitude Determination Frame and the LandIS Interface (mounting surface datums), which is captured in SCIRD-296. The details of how the mount must be oriented so as to put the LandIS boresight in the proper direction is left as a detailed item to be worked out by LandIS and spacecraft in the Interface Control Document (ICD).

3.2.1.4 Mass Properties

The defined not-to-exceed mass defined by the LandIS dimensional envelope includes the fully assembled instrument, LandIS-unique flexures, instrument-unique fastening hardware, thermal blankets, connectors (instrument-side only), LandIS deck, and intra-instrument harness (with connectors), as well as any other items that constitute any part of a deliverable instrument along with the IMSC hardware.

LIRD-160 LandIS shall have a total mass of not to exceed 550 kg (TBR) mass including all associated hardware, intra-LandIS harnessing, and any attached external harnessing extending to the spacecraft connector interface bracket.

Rationale: This does not include the IMSC mass. This is a NTE estimate, and the reserve is contained within. It does include the LandIS deck, flexures, blankets, fasteners.

LIRD-163 LandIS mass shall be measured to an accuracy of ± 0.2%.

LIRD-169 LandIS center of mass, including IMSC, shall be no more than TBD from the centerline of LandIS volume.

LIRD-171 LandIS moments and products of inertia are to be measured or calculated using coordinates based on the spacecraft axes but passing through the LandIS center of mass.

LIRD-172 LandIS moments and products of inertia values shall be accurate to within ± 5% for calculated values, and the lesser of 1.5% or 300 kg-cm² for measured values.

3.2.1.5 LandIS Access, Integration & Deintegration

LIRD-182 LandIS shall not require access to the opposite side of the spacecraft mounting interface for attachment or removal.

LIRD-184 LandIS shall allow for access to all telescope optical surfaces during I&T without disturbing alignment that would require telescope performance revalidation.

LIRD-219 LandIS items to be installed, removed, or replaced at the spacecraft level shall be accessible without disassembly of higher levels of assembly.

LIRD-220 LandIS shall be mechanically integrated or deintegrate vertically, with the spacecraft interface horizontal.

Rationale: LandIS should be lowered to the spacecraft interface. The -X spacecraft axis is pointing upward from the ground.

3.2.1.6 LandIS Mounting

LIRD-133 LandIS mechanical interface shall incorporate alignment pins to ensure precise placement and provide repeatability should removal and reinstallation ever be required.

LIRD-187 LandIS deck shall be mounted to the spacecraft with kinematic mounts.

Rationale: Flexures are provided by the Instrument Vendor.

LIRD-189 LandIS shall accommodate IMSC sensor components mounted to the LandIS deck.

Rationale: Specific locations and accommodations will be negotiated in the ICD development process. The LandIS contractor routes harnesses provide by the SC contractor, such as power, signal, and heater harnesses.

LIRD-196 The LandIS deck shall accommodate the mounting of all LandIS components within the LandIS allocated stowed volume.

LIRD-198 LandIS mounting interfaces to the spacecraft shall be in the +Y, +Z plane, in the anti-Ram face of the Spacecraft bus.

Rationale: The anti-ram, directional reference is based on the on-orbit configuration described in Figure 3.2.1.1-1. A more detailed image to be provided with IDD.

LIRD-192 LandIS structural model in the launch configuration shall have a first significant mode of no less than 45 Hz, when mounted to the spacecraft with flexures

Rationale: The requirement assumes measurements are with flexures. Prior experiences with instruments of this size suggest that 45 Hz is an appropriate stiffness metric for this stage of development.

LIRD-200 LandIS shall comply with not-to-exceed interface limit loads based upon the

Mass Acceleration Curve (MAC) for components as shown in Figure 3.2.1.6-1. Note: The MAC is expected to be superseded by a combined launch vehicle and Observatory coupled loads analysis (CLA), and the CLA will presumably be the driver for Observatory-level dynamics testing.

Rationale: These loads represent the quasi-static loads due to the low-frequency launch environment. The hardware should be designed for the loads given below as well as for loads induced by the high frequency random environment. The breakpoints for the MAC are given in

Table 3.2.1.6-1. Design loads shown below should be updated based on the results of coupled loads analysis. Linear interpolation may be used between break-points to determine limit loads.

Figure 3.2.1.6-1 Mass Acceleration Curve

Table 3.2.1.6-1 Component Design Loads (Break Points) Hardware Mass (kg) Quasi-static Load (g) 1 68.0 5 50.0 11 38.0 22 30.2 32 25.9 43 23.2 53 21.2 64 19.6 74 18.4 85 17.4 95 16.5 106 15.8 116 15.2 127 14.6 137 14.1 150 13.6 160 13.2 170 12.8 180 12.5 190 12.2 200 and above 12.0

LIRD-202 LandIS structural support components shall be designed to show positive margin for limit load using FS=1.25 for yield and FS=1.4 for ultimate, when constituted of MSFC-STD-3029 Table 1 materials. (TBR)

3.2.1.7 Instrument Mounted Spacecraft Components (IMSC) Sensor Accommodation LIRD-205 LandIS deck shall accommodate IMSC sensors such as gyros and star trackers provided by the spacecraft vendor.

LIRD-214 The IMSC volume shall not exceed a Star Tracker Subassembly volume of .18 m^3 (TBR) and a Scalable Inertial Reference Unite (SIRU) Subassembly volume of .12 m^3 (TBR).

Rationale: These IMSC volume numbers are not to exceed values. The IMSC volume is assumed to be bookkept within the LandIS volume.

LIRD-208 LandIS shall accommodate an IMSC total mass not to exceed 50 Kg (TBR) on the LandIS deck.

Rationale: Mass of IMSC which reside on the LandIS instrument deck are provided by SC. This allocation is part of the overall SC budget and not part of the instrument budget and includes power and data harnessing. This allocation includes all hardware, secondary structure, harness, MLI and MMOD blanketing.

LIRD-316 The thermal heat transfer between the LandIS deck and IMSC shall be less than or equal to 0.1 W/C (TBR) over the orbit average.

Rationale: Heat transfer to the IMSC cannot impact thermal conditions. This is in reference to the SC body to LandIS reference frame.

LIRD-211 The IMSC radiators shall have an unobstructed FOV of space opposite the direction of the sun.

Rationale: LandIS should not obstruct any SC radiators.

LIRD-213 LandIS shall provide an unobstructed glint free zenith-directed field of view for the star trackers in the IMSC of 25 deg (TBR) along track by 25 deg (TBR) cross-track.

3.2.2 Orbit Control, Pointing and Alignment

The values contained within this section are consistent with the LNEXT-SYS-DESC-0016 Rev -, Geometric Error Budget (GEB).

3.2.2.1 Pointing Stability and Jitter

LIRD-268 All FEMs used for jitter analysis shall incorporate a damping ratio of 0.25%.

Rationale: A consistent and appropriate damping ratio will allow for consistent interpretation of modeling results.

3.2.2.2 Alignment

LIRD-281 The Instrument Alignment References shall be viewable from two orthogonal directions when integrated to the Observatory.

LIRD-285 Each optical target or cube shall be covered with a flight quality (and flight capable) cover.

LIRD-286 The optical cube cover shall be removable during Integration and Test.

LIRD-287 The optical cube cover shall be installed prior to integration onto the launch vehicle.

LIRD-288 The cover shall provide captive hardware to prevent loose pieces if the cube comes loose.

Components of Boresight Alignment Knowledge Uncertainty resulting from alignment shifts allowed by clearances across the mounting interface (pin/fastener to hole tolerance) at the Instrument Interface (mounting surface datums) will be allocated to the LandIS.

LIRD-301 LandIS shall maintain alignment stability of 12 microradians or less, 3-sigma, per axis, from the VSWIR mounting interface to the Instrument Mounted Spacecraft Components mounting location, over any period of 1 orbit.

Rationale: The VSWIR to Instrument Mounted Spacecraft Components mounting location alignment must be stable over the orbit to ensure that the absolute geodetic accuracy requirements are met. Alignment drift is typically a combination of within-orbit drift and longer term seasonal drift. The seasonal component is amenable to ground calibration, but the within-orbit component is less so. LandIS deck material should be chosen to minimize detrimental distortions between the IMSC and the LandIS line of sight.

LIRD-299 LandIS shall maintain alignment stability of 1 microradian or less, 3-sigma, per axis, from the VSWIR mounting interface to the Instrument Mounted Spacecraft Components mounting location, over any period of 30 seconds.

Rationale: The VSWIR to Instrument Mounted Spacecraft Components mounting location alignment must be stable over the duration of 1 scene (approximately 30 seconds) to ensure that the geometric and band registration accuracy requirements are met.

LIRD-650 LandIS shall provide an IMSC interface that maintains alignment stability of

TBD microradians or less, 3-sigma, per axis, to the IMSC mounting interface, during a period of over 18 days.

Rationale: Goal is to avoid the LandIS deck deforming and affecting the IMSC alignment stability.

LIRD-651 LandIS shall provide an IMSC interface that maintains alignment stability of TBS microradians or less, per axis, to the IMSC mounting interface, during a period of over 30 seconds.

Rationale: Goal is to avoid the LandIS deck deforming and affecting the IMSC alignment stability.

3.2.2.3 Disturbance Torques

LIRD-478 LandIS shall maintain uncompensated momentum contribution not exceeding +/- 0.5 N-m-sec per axis. (TBR)

LIRD-487 LandIS shall maintain constant torques of 10 seconds duration or less to not exceed 0.004 N-m.

Rationale: The integration of torque x time of application for a constant level torque produces the integrated torque or momentum of 0.04 N-m-s. So, a 2 second time of application of torque could be up to 0.02 N-m.

Uncompensated LandIS disturbance forces should be analyzed as acting through the appropriate moment arms to the spacecraft center of mass (CM), and are subject to the torque limits previously defined.

LIRD-483 LandIS shall maintain periodic disturbance torque magnitudes, including torques resulting from linear forces reacting from the LandIS to the spacecraft within the acceptable range of Figure 3.2.2.3-1 for all frequencies.

All mechanical requirements specified are to be met at the mechanical interface; that is, at the surface(s) of the spacecraft where the LandIS is in contact with the spacecraft, unless otherwise specifically indicated.

LIRD-485 LandIS shall maintain constant disturbances within durations exceeding 10 seconds of the same polarity, separated by more than 200 seconds, within the torque limit defined in Figure Figure 3.2.2.3-1.

Rationale: LandIS-induced fixed-polarity torque that is greater than 10 seconds in duration have a maximum allowed magnitude as defined in Figure 3.2.2.3-2. The completion of a LandIS-induced fixed-polarity torque event and the onset of the next LandIS-induced fixed-polarity torque event shall be greater than or equal to 200 seconds. If the torque event exceeds 400 sec then the 400 sec value is held constant. For constant torques of 400 seconds duration or more, the torque limit is maintained at the 400 second limit shown in Figure 3.2.2.3-2.

Figure 3.2.2.3-1 Torque Limit

Figure 3.2.2.3-2 Torque Duration Limit

3.2.3 Thermal Interface Requirements

3.2.3.1 Operating & Survival Heaters and Temperatures

The operating and survival temperatures, as well as the thermal isolation requirements specified in this section are met at the mechanical interface between the spacecraft and the LandIS.

LIRD-306 LandIS shall use only power provided by its Main Bus survival power service for maintaining the LandIS survival heaters.

3.2.3.2 Thermal Allocations

LIRD-310 LandIS shall identify the location of operational temperature sensors and calibration data.

Rationale: Replace this requirement with information contained within the IDD.

3.2.3.3 Thermal Isolation

LIRD-317 The thermal heat transfer between the LandIS deck and the spacecraft shall be less than or equal to 0.1 W/C (TBR) over the orbit average.

3.2.4 Electrical Interface Requirements

3.2.4.1 Electrical Interfaces

LIRD-320 LandIS shall receive the following electrical interfaces and services from the spacecraft (TBR), by design.

-LandIS output data bus(es) and input bus(es) -Operational Power Service -Survival Heater Power Service -Grounding Interface -1 Pulse Per Second (PPS) Interface -Discrete commands and telemetry, as needed -Discrete Bilevel & Analog telemetry, as needed

Rationale: Interfaces represent known LandIS interfaces and those that may be required (designated as “as needed”), pending LandIS design. Note the reference to output bus(es) and input data bus(es) is intended to be logical or functional reference and does not necessarily imply a physical interface for each.

3.2.4.2 Power Allocation

LIRD-342 LandIS shall not exceed orbit average power of 350W (TBR).

Rationale: This number does include margin. Margin is maintained based on instrument lifecycle as specified in GSFC-STD-1000 Rev G, Rule 1.06. Note: This does not include the power required for any IMSC.

3.2.4.3 Main Bus Power

3.2.4.3.1 Main Bus Voltage Range

LIRD-351 LandIS Survival heaters shall be sized using a minimum Main bus voltage of

24 V (TBR) at the spacecraft interface.

Rationale: Ensure sufficient thermal control at a reduced voltage when the observatory is in a compromised state on-orbit that may prevent optimal power collection. The minimum Main bus voltage accounts for a least a single cell failure.

LIRD-355 LandIS shall operate and meet performance requirements for the Main bus voltage range of +27 to +35 VDC at the LandIS Main Bus power inputs.

Rationale: This defines Main Bus operational voltage range.

LIRD-363 LandIS shall survive exposure to a Main Bus voltage range of 0 to +40 VDC, for an indefinite period of time.

Rationale: This prevents the loss or damage to flight hardware that may result from human error or EGSE anomaly during ground processing.

3.2.4.3.2 Main Bus Power Quality

LIRD-358 LandIS shall meet all performance requirements in the presence of ripple voltages up to 1.5V peak-to-peak over the frequency range of 30 Hz to 150 kHz.

Rationale: This defines Main Bus power quality and conducted susceptibility limits at frequency range consistent with CS101.

LIRD-360 LandIS shall meet all performance requirements in the presence of ripple voltages up to 1V peak-to-peak over the frequency range of 150 kHz to 200 MHz.

Rationale: This defines Main Bus power quality and conducted susceptibility limits at frequency range consistent with CS114.

LIRD-475 LandIS shall provide EMI input filters installed on the LandIS side of the power interface.

LIRD-476 LandIS shall provide EMI filters with both common-mode and differential-mode filtering.

3.2.4.3.3 In-Rush Current Transients

LIRD-366 LandIS shall limit the amplitude and duration of in-rush currents, at both initial application of Main Bus power and subsequent internal component turn-on, to the following:

-850% load peak current for < 10 microsecond -250% load peak current for > 10 microsecond and < 10 milliseconds -100% load peak current for > 10 milliseconds

Rationale: Ensure that fault protection will not trip inadvertently due to turn-on transient, potentially rendering it difficult or impossible to turn on. Avoid damage to the power service due to the turn on transient. Minimize impact on Main Bus power quality.

3.2.4.3.4 Operational Transients

LIRD-369 LandIS shall limit the rate of change of the current for operational transients to be less than or equal to 20 milli-amperes/micro-seconds.

Rationale: Limits the impact on power quality by bounding Ldi/dt for operational transients.

3.2.4.4 Power Distribution Interfaces

LIRD-345 LandIS power service interfaces shall be sized such that peak load current derating requirements of EEE-INST-002 are met over the operational voltage range, with any single conductor failed open.

Rationale: Satisfy derating requirements for bundled wire in a vacuum, allowing for a single failed conductor that would not be detectable after flight mate.

LIRD-372 LandIS shall isolate the redundant, independent interfaces to S/C Main Bus power services, by > 1 Mohm (power to power; return to return).

Rationale: Provides added robustness through LandIS select redundancy.

LIRD-374 LandIS shall isolate main bus power returns from chassis ground by > 1

Mohm.

Rationale: Preserve the observatory SPG scheme to avoid stray current and minimize EMI.

LIRD-376 LandIS shall receive primary power from the spacecraft via separate connectors for the redundant operational and survival power services.

Rationale: Eliminate the possibility of catastrophic connector failure disabling both power services. It also ensures compliance with GSFC-STD-1000 Rev G, Rule 2.18.

LIRD-378 LandIS shall isolate any single fault occurring on either the prime or redundant Main Bus power service such that it cannot propagate to the opposite power service.

Rationale: Prevents failure of one power service from disabling both and resulting in loss of LandIS.

3.2.4.5 Instrument Suite Class R Grounding Interface

LIRD-382 Where the primary Class-R ground path from LandIS CGP to Observatory

CGP is via the LandIS mounting surface, the LandIS shall be electrically conductive and have sufficient surface area and flatness to achieve a bonding resistance of 2.5 milliohms, or less, when installed with all fasteners torqued to the specified values.

Rationale: Prevent high frequency radiated emissions from interfering with electronics by implementation of NASA-STD-4003A Class R grounding methods.

LIRD-384 Where the primary Class-R ground path from LandIS CGP to Observatory

CGP is via ground straps, LandIS shall provide a minimum of three electrically conductive attach points, having sufficient surface area to achieve a bonding resistance of < 2.5 milliohms, with ground strap lugs installed and fasteners torqued to the specified values.

implementation of NASA-STD-4003A Class R grounding methods. Note: To the extent practical, ground strap attach points should be located equidistant from one another, around the perimeter of the component.

LIRD-386 Where the primary Class-R ground path from LandIS CGP to Observatory

CGP is via ground straps, LandIS shall achieve a resistance, as measured from the LandIS CGP to the Observatory CGP, of < 5 milliohms, with all ground straps installed and all ground strap fasteners torqued to specified values.

implementation of NASA-STD-4003A Class R grounding methods.

LIRD-655 Where ground straps are used as the primary Class-R ground path from the

LandIS CGP to the Observatory CGP, the ground straps shall be designed with a length-to-width ratio of ≤ 5-to-1.

Rationale: Minimize skin effects and inductance to effectively conduct high frequency energy that may result in EMI. This assumes LandIS supplies the ground straps.

3.2.4.6 Electric Harnesses and Connectors

3.2.4.6.1 Power Signal Circuits

LIRD-640 LandIS shall use separate connectors for power and signal circuits.

Rationale: Prevent EMI of power conductors coupling to signals.

3.2.4.6.2 Electrical Connectors

LIRD-335 LandIS shall have exposed contacts on all connectors receiving Main Bus or secondary power.

Rationale: Prevent inadvertent shorting of an unmated, harness connectors when powered during ground processing.

3.2.4.6.3 Keying

LIRD-644 LandIS shall key connectors of the same type and gender, including test connectors not intended for flight harness mating, where accidental mis-mate is possible and could cause damage to the hardware, or pose a safety hazard.

Note: A mis mate is considered possible ONLY if the like connectors are located in such close proximity as to allow the incorrect mating connectors on the harness to reach.

Rationale: Prevent damage to flight hardware during ground processing due to inadvertent mis-mate of connectors.

3.2.4.6.4 Flight Plugs

LIRD-646 LandIS flight plugs requiring installation prior to launch shall be capable of being installed at the payload level.

Rationale: Ensure that flight plugs are accessible at the required points during ground processing.

3.2.5 Command and Data Handling

3.2.5.1 Data Bus(es)

Figure 3.2.5.1-1 LandIS Functional Data Buses

LandIS Output Data Bus: The interface bus where the data set containing LandIS data is transported to the spacecraft. LandIS output data is imaging sensor data, Instrument ancillary data or housekeeping data. LandIS imaging sensor data may be detector image data, test pattern data or raw detector diagnostic data. It is a functional reference and not intended to be a physical reference. LandIS Input Data Bus: The interface bus where the data set containing commands is transported from the spacecraft. It is a functional reference and not intended to be a physical reference.

LIRD-408 The physical layer of the output data bus(es) and input data bus(es) shall be differential and a space qualified standard.

Rationale: The references to data bus is a functional interface and is not meant to imply a physical interface requirement.

LIRD-404 The LandIS shall provide LandIS imaging sensor data via an output data bus at a maximum rate no greater than 2.5 Gbps per channel.

Rationale: More than 1 channel may be required to provide the 5 second of data collection.

LIRD-405 The LandIS shall provide LandIS imaging sensor data via an output data bus at a minimum rate no less than TBS.

LIRD-406 LandIS shall provide meta data with image sensor data to the SC for storage and downlink

LIRD-391 LandIS shall provide a limited amount (TBD) of LandIS FPA & test pattern data and raw detector diagnostic data to the spacecraft over an output data bus.

LIRD-538 LandIS shall limit the size of the LandIS imaging sensor data delivered to the SC for storage to no more than 5 seconds per data file. (TBR)

Rationale: The 5 seconds of data collection is intended to limit the file size to no more than 2 Gbytes. At worst case, each block of sensor data delivered by the instrument will be<=5 (TBR) seconds of image collection and therefore should not exceed 2 GB, which is well below the 4 GB limit required to comply with the CCSDS encapsulation standard used by the spacecraft. In addition, limiting the duration of imaging contained within a single file limits the impact if a file is lost (a single file will never contain more than 1/5 of a scene)

LIRD-665 LandIS shall send an end of data marker to the spacecraft indicating the end of an imaging sensor data block.

LIRD-412 LandIS ancillary data shall be sent to the spacecraft over an output data bus.

LIRD-397 LandIS shall provide uncompressed housekeeping data to the spacecraft over an output data bus.

Rationale: Instrument housekeeping data provides valuable information to monitor the health and safety of the LandIS.

LIRD-656 LandIS shall provide telemetry diagnostic data to the spacecraft over an output data bus

LIRD-398 LandIS shall provide memory dumps to the spacecraft over an output data bus, upon command.

LIRD-436 LandIS shall provide telemetry as polled by the spacecraft at a frequency of

TBS.

Rationale: Need to have a deterministic telemetry for LandIS housekeeping, health and safety status of the instrument.

LIRD-393 LandIS shall receive commands from the spacecraft over an input data bus.

Rationale: The commands are inclusive of ground commands, spacecraft stored commands, files, memory and table loads.

LIRD-396 The LandIS shall provide the time-of-day time code over a command and telemetry data bus.

3.2.5.2 Time-of-day Signal

LIRD-425 LandIS shall receive a 1 Hz time-of-day signal from the spacecraft to indicate the point in time at which to apply the time-of-day message which was previously transmitted by the spacecraft.

LIRD-426 LandIS shall utilize the rising edge of the time-of-day signal, together with the time-of-day message, in order to establish the time reference for LandIS data.

3.2.5.3 Discrete Commands

LIRD-414 LandIS shall provide dedicated, redundant discrete command interfaces for all discrete command functions.

Rationale: Provides added robustness through LandIS select redundancy.

LIRD-416 LandIS discrete commands shall have returns isolated from the chassis ground and secondary power returns by > 1 MOhm, at the LandIS.

LIRD-418 Discrete commands interfaces shall be designed to return current over a dedicated return line.

Rationale: Minimize EMI effects due to pulsed discrete commands

LIRD-420 LandIS shall accept and execute discrete commands having the following characteristics:

a. Inactive: Amplitude: -2.0 to +4.0 VDC

b. Active: Amplitude: +22 VDC to +36 VDC

c. Pulse Width: 80 +/- 20 milliseconds

d.…