Attachment C - GIRD.pdf

Effective Date: February 10, 2022 418-XO-GIRD-0041 Responsible Organization: GeoXO Flight Project/Code 418 Baseline Version 1.0

Geostationary and eXtended Observations (GeoXO) General Interface Requirements Document (GIRD)

Signature page

Prepared by:

Electronically approved by:

01/26/2022

Derrick A. Early Date GeoXO Flight Project, Systems Engineer NASA GSFC, Code 418

Reviewed by:

02/10/2022

Steven W. Bidwell Date GeoXO Flight Project, Mission Systems Engineer NASA GSFC, Code 599

02/04/2022

Michelle P. Rizzo Date GeoXO Flight Project, Observatory Manager

Approved by:

02/10/2022

Jason Hair Date GeoXO Flight Project, Project Manager NASA GSFC, Code 418

/GeoXO Flight Project Systems Engineering

GIRD

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document (GIRD)

Version: 1.0 Printed by: rkhoover Printed on: Wednesday, February 16, 2022

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Contents

1 1Scope

1.1 1Introduction

1.2 1Requirements Terminology

1.3 1Order of Precedence

1.4 1Definitions

2 3Documents

2.1 3Applicable Documents

2.2 3Reference Documents

3 5Requirements

3.1 5General Requirements

3.1.1 5Instrument Modes

3.1.1.1 5Power Off Mode

3.1.1.2 5Instrument Safe Mode

3.1.1.2.1 5Instrument Safe Mode Command

3.1.1.2.2 5Instrument Safe Mode Timeout

3.1.1.3 5Survival and Storage Modes

3.1.2 5Operational Concepts

3.1.2.1 5Pre-Launch

3.1.2.2 5Launch and Orbit Raising

3.1.2.3 5On-Orbit Concept

3.1.3 6Dimension Standard

3.1.4 6Coordinates

3.1.5 7Yaw Flip

3.2 7Interface Requirements

3.2.1 7Mechanical

3.2.1.1 7Envelope Documentation

3.2.1.2 7Critical Clearances

3.2.1.3 7Fields of View

3.2.1.4 8Mass Properties

3.2.1.4.1 8Center of Mass

3.2.1.4.2 8Inertia Properties

3.2.1.5 8Mounting

3.2.1.5.1 8Mounting Hardware

Project: GeoXO Flight Project Systems Engineering Module: GIRD Baseline Version: 1.0

Contents ii

3.2.1.5.2 8Mounting Method

3.2.1.5.3 9Handling Fixtures

3.2.1.5.4 9Interface

3.2.1.5.5 9Location

3.2.1.5.6 9Drill Templates

3.2.1.6 10Alignment

3.2.1.6.1 10Nadir Pointed Instrument Alignment

3.2.1.6.1.1 10Alignment References

3.2.1.6.1.2 10Alignment Responsibilities

3.2.1.6.1.3 10Instrument Placement

3.2.1.6.1.4 10Initial Alignment Knowledge

3.2.1.6.1.5 11Alignment Rate of Change

3.2.1.7 11Instrument Access

3.2.1.8 11Attitude and Disturbances for Nadir Pointed Instruments

3.2.1.8.1 11Spacecraft Attitude and Disturbances

3.2.1.8.1.1 11Attitude Error

3.2.1.8.1.2 11Attitude Rate Error

3.2.1.9 12Flight and Non-Flight Equipment

3.2.2 12Thermal

3.2.2.1 12Thermal Control Concept

3.2.2.1.1 13Independent Unit - Net Heat Transfer

3.2.2.1.2 13Coupled Unit – Heat Transfer

3.2.2.1.3 13Coupled Unit - Heat Transfer Flux Density

3.2.2.2 13Interface Temperatures

3.2.2.3 13Temperature Monitoring

3.2.2.3.1 13Mechanical Interface Temperature Monitoring

3.2.2.3.2 13Instrument Critical Temperatures

3.2.2.3.3 14Instrument Non-Critical Temperatures

3.2.2.4 14Thermal Interfaces

3.2.2.4.1 14Mounting Details

3.2.2.4.2 14Contact Area

3.2.2.4.3 14Interstitial Materials

3.2.2.5 14Multi-layer Insulation

3.2.3 14Instrument Electrical Power

3.2.3.1 14Electrical Power Interfaces

3.2.3.2 15Power Specifications

3.2.3.2.1 15Power Definitions

3.2.3.2.2 15Power Characteristics

Contents iii

3.2.3.2.2.1 15Voltage

3.2.3.2.2.1.1 15Instrument Voltage

3.2.3.2.2.1.2 16Voltage Transients

3.2.3.2.2.1.3 16Abnormal Operation Voltage Limits

3.2.3.2.2.1.4 16Spacecraft Unpowered Voltage

3.2.3.2.2.1.5 16Voltage Power Source Impedance

3.2.3.2.2.2 17Current

3.2.3.2.2.2.1 17Operational Power Transients

3.2.3.2.3 17Power Distribution, Control, and Status

3.2.3.2.3.1 17Operational Power Lines

3.2.3.2.3.2 18Operational Power ON/OFF Functionality

3.2.3.2.3.3 18Operational Power Overcurrent Protection

3.2.3.2.3.4 18Survival Heater Power Lines

3.2.3.2.3.5 18Survival Heater Power On/Off Functionality

3.2.3.2.3.6 19Survival Heater Power Overcurrent Protection

3.2.3.2.3.7 19Abnormal Survival Power Voltage Limits

3.2.4 19Instrument Electrical Power Grounding

3.2.4.1 19Instrument Operational Power Grounding

3.2.4.2 20Instrument Survival Heater Power Grounding

3.2.4.3 21Instrument Secondary Power Grounding

3.2.4.4 21Instrument Electrical Signal Grounding

3.2.4.4.1 21Instrument Command Grounding

3.2.4.4.1.1 21Instrument Pulse Command Grounding

3.2.4.4.1.2 21Instrument Serial Command Grounding

3.2.4.4.1.3 21Instrument Electro-Explosive Device (EED) Command Grounding

3.2.4.4.2 21Instrument Telemetry Grounding

3.2.4.4.2.1 21Instrument Analog Telemetry Grounding

3.2.4.4.2.2 22Instrument Serial Telemetry Grounding

3.2.4.5 22Instrument Electrical Accommodations

3.2.4.5.1 22Spacecraft/Instrument Interface Harnessing

3.2.4.5.2 22Spacecraft/Instrument Telemetry and Command Interface Harnessing

3.2.5 22Command and Data Handling

3.2.5.1 22Data Transfer Between the Instrument and Spacecraft utilizing SpaceWire

3.2.5.2 22Guaranteed Delivery

3.2.5.3 23SpaceWire Data Bus

3.2.5.3.1 23SpaceWire Redundancy

3.2.5.4 23Source Packet Format

3.2.5.4.1 23Source Packet Length

Contents iv

3.2.5.4.2 23Secondary Header Flag

3.2.5.4.3 23Source Packet Secondary Header

3.2.5.4.4 24Sequence Flags

3.2.5.4.5 24User Defined Flags

3.2.5.5 24SpaceWire Data Rate

3.2.5.6 24Pulse Per Second (PPS)

3.2.5.6.1 24SpaceWire Time Code Support

3.2.5.6.2 24PPS Signal Drift

3.2.5.6.3 24Time Message

3.2.5.6.4 25Time Code Format

3.2.5.6.5 25Epoch

3.2.5.6.6 25Distribution Timing

3.2.5.7 25Ancillary Data

3.2.5.7.1 25Ancillary Packet Rate

3.2.5.8 25Control and Monitoring

3.2.5.8.1 25Critical Telemetry

3.2.5.8.2 26Critical Telemetry Analog Signals

3.2.5.8.3 26Critical Telemetry Analog Signal Resolution

3.2.5.8.4 26Discrete Signals

3.2.5.8.5 26Critical Telemetry Signal Characteristics

3.2.5.8.6 26Instrument Configuration Commands

3.2.5.8.6.1 27Configuration Command Definition

3.2.5.8.7 27Stored Command Processing

3.2.6 27Environmental Conditions

3.2.6.1 27On-Orbit Radiation Environment

3.2.6.2 27Launch Environment

3.2.6.2.1 27Thermal Environment During Launch

3.2.6.2.2 27Pressure Profile

3.2.6.2.3 28Flight Acceleration

3.2.6.2.4 30Flight Random Vibration

3.2.6.2.5 32Flight Sinusoidal Vibration

3.2.6.2.6 34Shock

3.2.6.2.7 36Flight Acoustics

3.2.6.3 37On-Orbit Environment

3.2.6.3.1 38Acceleration

3.2.6.3.2 38Orbital Heat Flux

3.2.6.3.2.1 38Direct Solar Flux

3.2.6.3.2.2 38Solar Eclipse

Contents v

3.2.6.3.2.3 38Extended Solar Eclipse

3.3 38Attitude and Orbit Data

3.3.1 38Attitude Knowledge

3.3.1.1 38Attitude Knowledge Representation

3.3.1.2 38Attitude Knowledge Accuracy

3.3.1.3 39Attitude Knowledge Update Rate

3.3.1.4 39Attitude Knowledge Latency

3.3.2 39Spacecraft Angular Rate

3.3.2.1 39Angular Rate Representation

3.3.2.2 39Angular Rate Accuracy

3.3.2.3 39Angular Rate Bandwidth

3.3.2.4 39Angular Rate Update Rate

3.3.2.5 39Angular Rate Latency

3.3.3 40Spacecraft Orbit

3.3.3.1 40Spacecraft Orbit Representation

3.3.3.2 40Spacecraft Orbit Accuracy

3.3.3.3 40Spacecraft Orbit Update Rate

3.3.3.4 40Spacecraft Orbit Latency

3.3.3.5 40Spacecraft Orbit Stability

3.4 41Instrument GSE to Spacecraft I&T GSE Interface

3.5 41Contamination Control

3.5.1 41Instrument and Spacecraft Ground Processing

3.5.1.1 41Facility Requirements

3.5.1.2 41Ground Support Equipment Requirements

3.5.1.3 42Purge Requirements

3.5.1.4 42Ground Storage/Transportation Requirements

3.5.2 43Mission Contamination Considerations

3.5.2.1 43Thermal Blanket Design

3.5.2.2 43Particulate Contamination

3.5.2.3 43Molecular Contamination

4 45Requirements Verifications

4.1 45EMC – General

4.2 45Conducted Emissions

4.3 46Common Mode Noise

4.4 46Conducted Susceptibility

4.5 49Operational Power Voltage Ripple

4.6 50Radiated Susceptibility and Emissions

Contents vi

4.6.1 50Radiated Susceptibility, Spacecraft/Launch Environment

4.6.2 52Radiated Emissions

5 55Acronyms

Contents vii

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418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

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1 Scope

1.1 Introduction

This General Interface Requirements Document (GIRD) sets forth the general, mechanical, thermal, electrical power, command and data handling and contamination control interface requirements imposed on both the instruments and spacecraft for the GeoXO Series System. It also defines the general environments to which the satellite will be subjected. The spacecraft contractor and the instrument contractor will each meet their respective interface requirements defined in this document.

The Unique Instrument Interface Document (UIID) for an instrument defines the specific resource allocations, documents exceptions to the GIRD requirements and constraints, and defines the special requirements not specifically covered in the GIRD.

The instrument contractor will create and maintain, with government approval, an Instrument Descriptive Document (IDD) which describe the detail instrument design and unique interface requirements. The GIRD, in conjunction with the UIID and the IDD establishes the instrument-to-spacecraft interface requirements.

Interface Control Documents (ICDs) will define the specific details of the complete spacecraft to instrument interface information (i.e., mechanical, electrical power, command and data handling, and thermal interfaces). These will be developed by the spacecraft contractor to document the Instrument-Spacecraft interface. The spacecraft contractor will control the ICDs and the ICDs will replace the related IDDs.

1.2 Requirements Terminology

The following requirements terminology is used throughout this document:

The use of “shall” designates a requirement that must be met.

The use of “will” designates a statement of fact or intention of the government.

The use of “may” designates that permission has been granted by the government.

The term “(TBD)” means, “to be determined” and is used when no value is available with subsequent study needed to obtain it.

The term “(TBR)” means “to be refined/reviewed” for a value that is subject to review for appropriateness and is subject to revision. The vendor is liable for compliance with the information marked “TBR” as if the “TBR” notation did not exist.

1.3 Order of Precedence

The order of precedence of interface requirements documents is the UIID at the highest level, followed in order by the GIRD, ICD, and IDD.

1.4 Definitions

Architecture and Design - A description of the mission elements, their interfaces, their logical and physical layout, and the analysis of the design to determine expected performance and margins, including System Design Synthesis, System Design Analysis, and System Design Validation products.

Assembly - A functional subdivision of a component consisting of parts or subassemblies that perform functions necessary for the operation of the component as a whole. Examples are power amplifier and gyroscope.

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Object Number

1.4.0-3

1.4.0-4

1.4.0-5

1.4.0-6

1.4.0-7

1.4.0-8

1.4.0-9

1.4.0-10

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1.4.0-16

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Component - A functional subdivision of a subsystem and generally a self-contained combination of items performing a function necessary for subsystem operation. A functional unit viewed as an entity for purpose of analysis, manufacturing, testing, or record keeping.

Element - A complete, integrated set of subsystems capable of accomplishing an operational role or function.

Part - A hardware element, which is not normally subject to further subdivision or disassembly without destruction of designated use.

Subsystem - A functional grouping of components that combine to perform a major function within an element.

Satellite - The GeoXO Satellite consists of the Spacecraft and GFE science instrument payload.

Spacecraft - The Spacecraft consists of the flight hardware and software required to accommodate the science instrument payload. The Spacecraft includes the DCPR auxiliary communication.

Spacecraft Bus - Satellite without instruments and DCPR auxiliary communication.

System - A composite of hardware, software, skills, personnel, and techniques capable of performing and/or supporting an operational role. A complete system includes related facilities, equipment, materials, services, software, technical data, and personnel required for its operation and support to the degree that it can be considered a self-sufficient unit in its intended operational and/or support environment. The system is what is employed operationally and supported logistically.

(More than one system may be needed to conduct a mission)

Unit - Defined to be a functional subdivision of an instrument, such as an Electronics Box or Power Supply Box or cryocooler.

Validation - Proof that the Operations Concept, Requirements, and Architecture and Design will meet Mission Objectives, that they are mutually consistent, and that the “right system” has been designed.

Validation Basis - A set of requirements that provide the success criteria for a system or system element.

Verification - Proof of compliance with requirements and that the system has been “Designed and Built Right.” May be determined by a combination of test, analysis, and inspection.

Critical telemetry - telemetry points that are required to monitor the instrument in powered OFF state.

Non-critical telemetry - telemetry points that are required to monitor the instrument in powered ON state.

Engineering telemetry - data required to process instrument sensor data to higher level products.

Housekeeping telemetry - data required to monitor instrument operation, health, and safety.

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2.1

2.1.0-1

2.2

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

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2 Documents

2.1 Applicable Documents

The following documents of the exact issue shown form a part of this GIRD to the extent specified herein. In the event of conflict between the documents referenced and the contents of this GIRD the latter shall be the superseding requirement.

⦁ 418-XO-RPT-0039 - GOES Reliable Data Delivery Protocol (GRDDP).

⦁ 418-XO-RPT-0042 - Radiation Environment for Electronic Devices on the

GeoXO Series Satellites.

⦁ CCSDS 133.0-B-2 Space Packet Protocol, Blue Book, Issue 2, June 2020.

⦁ CCSDS 301.0-B-4 - Time Code Formats. Blue Book. Issue 4, November 2010.

⦁ CCSDS 660.0-B-2 – XML Telemetric and Command Exchange, Version 1.2, February 2020.

⦁ ECSS-E-ST-50-12C Rev.1 – European Cooperation for Space Standardization

(ECSS), SpaceWire – Links, nodes, routers and networks, 15 May 2019.

⦁ ECSS-E-ST-50-14C - Spacecraft discrete interfaces, 31 July 2008.

⦁ GSFC-STD-7000B – General Environmental Verification Standard (GEVS) for

GSFC flight Programs and Projects, 28 April 2021.

⦁ IEEE/ASTM SI-10 - American National Standard for Metric Practice, 2016.

⦁ ISO 14644-1:2015 Cleanrooms and associated controlled environments - Part

1: Classification of air cleanliness by particle concentration, December 15, 2015.

⦁ ISO 14644-3:2019 Cleanrooms and associated controlled environments - Part 3: Test methods, September 1, 2019.

⦁ MIL-STD-461C – Electromagnetic Emission and Susceptibility Requirements for the Control of Electromagnetic Interference, 4 August 1986.

⦁ MIL-STD-461G – Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment, 11 December 2015.

⦁ MIL-PRF-27401G – Propellant Pressurizing Agent, Nitrogen, 7 August 2013.

⦁ PRC-5001 Rev G – Process Specification for Cleaning Hardware, June 2020.

⦁ USNO Circular 179 - The IAU Resolutions on Astronomical Reference Systems, Time Scales, and Earth Rotation Models 20 October 2005.

2.2 Reference Documents

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⦁ CCSDS 701.0-B-3 - Recommendations for Advanced Orbiting Systems, Networks and Data Links, Architectural Specification, June 1, 2001

⦁ CCSDS 660.1-G-1 – XML Telemetric and Command Exchange (XTCE) – Element Description, May 2012.

⦁ Farrenkopf, R.L., "Analytic Steady-State Accuracy Solutions for Two Common Spacecraft Attitude Estimators," Journal of Guidance and Control (Reston, VA:

American Institute of Aeronautics and Astronautics), July-August, 1978, Vol.1, No.4, pp.282-284.

⦁ Markley, F. Landis, and R.G. Reynolds, "Analytic Steady-State Accuracy of a Spacecraft Attitude Estimator," Journal of Guidance, Control, and Dynamics (Reston, VA: American Institute of Aeronautics and Astronautics), November- December, 2000, Vol.23, No.6, pp.1065- 1067.

⦁ Wertz, J.R., Spacecraft Attitude Determination and Control, edited by James R.

Wertz (Boston: Reidel, 1978), pp.268-270.

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3.1

3.1.1

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3.1.1.2.2.0-1

3.1.1.3

3.1.1.3.0-1

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3.1.2

3.1.2.1

3.1.2.1.0-1

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418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

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3 Requirements

3.1 General Requirements

3.1.1 Instrument Modes

3.1.1.1 Power Off Mode

The Instrument Power OFF Mode shall not draw operational power.

3.1.1.2 Instrument Safe Mode

3.1.1.2.1 Instrument Safe Mode Command

The instrument shall enter Instrument Safe Mode upon receipt of a safing command from the spacecraft.

3.1.1.2.2 Instrument Safe Mode Timeout

The instrument shall enter Instrument Safe Mode upon the detection of 10 consecutive missing time messages.

3.1.1.3 Survival and Storage Modes

The spacecraft shall provide survival heater power in Survival and Storage modes.

The instrument shall not draw operational power while in Survival and Storage modes.

3.1.2 Operational Concepts

3.1.2.1 Pre-Launch

The satellite will be transported to the launch site where final vehicle preparations and checkout will be accomplished.

Final system verification tests will be accomplished prior to launch.

Instrument testing and inspection to be accomplished at the launch site will be documented in the ICD.

3.1.2.2 Launch and Orbit Raising

The instrument will be in Survival Mode during launch.

The instrument contractor will identify in the IDD the required configuration of the instrument for the launch environment, and the power required, in the event the mode is to be anything other than OFF, and also to document required sequences leading up to the pre-launch OFF mode.

3.1.2.3 On-Orbit Concept

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3.1.2.3.0-1

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3.1.2.3.0-4

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The satellite will operate in a geosynchronous orbit (Semi-major axis of approximately 42,164 km) located between 75 degrees and 137 degrees west longitude. Normal on-orbit operations entail periodic station keeping maneuvers that keep the satellite within a 0.05 degrees inclination about the equator and within 0.05 degrees of the on-station longitude.

The instrument with associated ground processing algorithms shall meet all functional and performance requirements when stationed in geostationary orbit within +/- 0.5 degrees of the spacecraft’s reference longitude and with an inclination up to 0.5 degrees.

The spacecraft and instrument shall operate at any reference longitude between 5 degrees West and 148 degrees West longitude.

Products shall be generated from the viewpoint of a satellite at the designated longitude at zero inclination.

Instruments shall survive an anomaly resulting in a static instrument line-of-sight (LOS) such that the sun passes through the LOS at orbit rate.

Instruments, while operational, shall survive a spacecraft attitude anomaly resulting in the sun being at an arbitrary fixed location within the instrument field of regard (FOR) for an indefinite period of time.

Instruments shall survive the sun sweeping through the field-of-view (FOV) of the instrument radiator from “horizon to horizon” at a rate of 6 degrees per minute, passing through radiator normal.

3.1.3 Dimension Standard

For all documents related to instrument interfaces, the spacecraft and instrument contractors shall use the International System of Units (SI) for all measurement units in accordance with IEEE/ASTM SI-10. The contractor may include English units in parenthesis for clarification.

3.1.4 Coordinates

The orbit reference frame (ORF) shall be defined as follows:

The ORF is orthogonal and right-handed.

The ORF origin is at the spacecraft center of mass.

The ORF +z axis points toward the center of the Earth.

The ORF +y axis points along the negative orbit normal.

The ORF +x axis completes the triad.

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3.1.4.0-2

3.1.4.0-3

3.1.4.0-4

3.1.5

3.1.5.0-1

3.2

3.2.0-1

3.2.1

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3.2.1.1.0-3

3.2.1.2

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The body reference frame (BRF) shall be defined as follows:

The BRF is orthogonal and right-handed.

The BRF is fixed to the body of the spacecraft.

The location of the BRF origin will be specified by the spacecraft contractor.

The BRF axes are nominally parallel to the ORF axes when spacecraft attitude is in its nominal Earth-pointing, upright yaw attitude with zero attitude error.

The roll, pitch, and yaw axes are defined to be parallel to the BRF x, y, and z axes, respectively.

The reference coordinate system of each instrument unit shall be nominally parallel to the spacecraft BRF coordinate system.

The origin of the coordinate system of each instrument unit shall be located and defined inside the mechanical envelope of the instrument unit.

3.1.5 Yaw Flip

Instruments shall meet all performance requirements whether or not the spacecraft performs a yaw flip.

3.2 Interface Requirements

All instrument-to-spacecraft interfaces shall be single fault tolerant. This does not include primary mechanical load paths for kinematic mounts.

3.2.1 Mechanical

3.2.1.1 Envelope Documentation

The instrument contractor will document the instrument unit envelopes in the IDD by engineering drawings with a set of “not to exceed” dimensions. The instrument envelopes will be inclusive of the thermal blankets.

The instrument contractor will ensure that the swept or deployed volume includes tolerances, distortions and misalignments.

The instrument contractor will include any harness constraints including bend radiuses in the IDD.

3.2.1.2 Critical Clearances

The spacecraft contractor will position the instrument units on the spacecraft to ensure that the stowed, deploying, and final deployed positions of the instrument units clear all obstacles including obstacles on the spacecraft, and other instruments.

The spacecraft shall maintain a minimum of 2.5 cm clearance between the instrument units and surrounding structure.

The spacecraft contractor will implement a critical clearance analysis to ensure that the clearance rule is not violated.

3.2.1.3 Fields of View

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GIRD92

GIRD93

GIRD94

GIRD95

GIRD96

GIRD97

GIRD98

GIRD99

Object Number

3.2.1.3.0-1

3.2.1.4

3.2.1.4.0-1

3.2.1.4.0-2

3.2.1.4.1

3.2.1.4.1.0-1

3.2.1.4.1.0-2

3.2.1.4.2

3.2.1.4.2.0-1

3.2.1.4.2.0-2

3.2.1.4.2.0-3

3.2.1.5

3.2.1.5.1

3.2.1.5.1.0-1

3.2.1.5.1.0-2

3.2.1.5.1.0-3

3.2.1.5.1.0-4

3.2.1.5.2

3.2.1.5.2.0-1

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

The instrument contractor will document the instrument field-of-view requirements in the IDD.

3.2.1.4 Mass Properties

The mass of the instrument units will be measured with an accuracy of 0.5 kg.

The nominal launch mass with tolerances of each instrument unit will be provided to the spacecraft contractor for documentation in the ICD.

3.2.1.4.1 Center of Mass

The instrument contractor will determine the centers of mass for each flight instrument unit relative to the instrument unit coordinate system with an accuracy of 5 mm including launch and deployed configurations.

The launch and deployed centers of mass with tolerances of each instrument unit will be provided to the spacecraft contractor for documentation in the ICD, referenced to the instrument coordinate axes.

3.2.1.4.2 Inertia Properties

The instrument unit moment of inertia will be defined using the instrument unit coordinate frame passing through the instrument center of mass.

The instrument contractor will determine the moments and products of inertia values with an accuracy of 5% of the maximum principal moment of inertia.

The launch and deployed moments and products of inertia with tolerances of each separately mounted instrument unit, referenced to the instrument coordinate axes, will be provided to the spacecraft contractor for documentation in the ICD.

3.2.1.5 Mounting

3.2.1.5.1 Mounting Hardware

The spacecraft contractor will define and document all mounting hardware in the ICD and indicate the hardware provider.

Unless otherwise specified, the spacecraft contractor will provide all mounting hardware for the instrument units.

The instrument contractor will provide all kinematic mounts.

The instrument units will be delivered to the spacecraft contractor with flight mounts installed.

3.2.1.5.2 Mounting Method

The instrument units, excluding the sensor unit, shall mount to the spacecraft with the spacecraft mounting surface in the vertical or in the horizontal position with the spacecraft mounting surface normal pointing up.

Page 9 of 56 Printed Wednesday, February 16, 2022

ID

GIRD100

GIRD101

GIRD102

GIRD103

GIRD104

GIRD105

GIRD106

GIRD107

GIRD108

GIRD109

GIRD110

GIRD111

GIRD112

GIRD113

GIRD114

GIRD115

GIRD116

GIRD117

GIRD118

Object Number

3.2.1.5.2.0-2

3.2.1.5.2.0-3

3.2.1.5.2.0-4

3.2.1.5.2.0-5

3.2.1.5.3

3.2.1.5.3.0-1

3.2.1.5.3.0-2

3.2.1.5.3.0-3

3.2.1.5.4

3.2.1.5.4.0-1

3.2.1.5.4.0-2

3.2.1.5.5

3.2.1.5.5.0-1

3.2.1.5.5.0-2

3.2.1.5.6

3.2.1.5.6.0-1

3.2.1.5.6.0-2

3.2.1.5.6.0-3

3.2.1.5.6.0-4

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

The instrument sensor unit shall mount to the spacecraft with the spacecraft mounting surface in the horizontal position with the spacecraft mounting surface normal pointing up.

For instrument units with a mass greater than 15 kg, a minimum of three lifting points shall be provided.

The design of the lifting points shall allow handling with an overhead crane including when the unit is in its flight configuration.

The method by which each instrument unit is mounted to the spacecraft will be defined in the ICD.

3.2.1.5.3 Handling Fixtures

The instrument contractor will provide proof tested handling fixtures for each unit with a mass greater than 15 kg.

Handling fixtures shall be designed to 5 times limit load for ultimate and 3 times limit load for yield.

Handling fixtures will be tested to 2 times working load.

3.2.1.5.4 Interface

The spacecraft mounting surface shall be flat to less than 0.83 mm per meter peak to peak.

The spacecraft contractor working with the instrument contractor will define the mechanical mounting interface requirements for each instrument unit in the ICD.

Requirements include surface flatness, finish, mounting bolt size, number, material, and torque limits.

3.2.1.5.5 Location

The spacecraft contractor working with the instrument contractor will define and document the location and orientation of instrument units on the spacecraft in the

ICD.

Coordinates and dimensions of the holes for mounting hardware will be specified at the mechanical interface and defined in the ICD.

3.2.1.5.6 Drill Templates

The pattern of mounting holes in a unit shall allow like units to be interchanged.

Instrument unit, spacecraft, and test fixture interfaces shall be drilled using templates to correctly establish the pattern of the mounting holes.

The drill template shall include appropriate alignment, orientation and location reference information and alignment cubes if required.

The spacecraft contractor will document functional requirements, and orientation information for the drill templates in the ICD.

Page 10 of 56 Printed Wednesday, February 16, 2022

ID

GIRD119

GIRD120

GIRD121

GIRD122

GIRD123

GIRD124

GIRD125

GIRD126

GIRD127

GIRD128

GIRD129

GIRD130

GIRD131

GIRD132

GIRD133

GIRD134

GIRD135

GIRD136

GIRD137

Object Number

3.2.1.5.6.0-5

3.2.1.6

3.2.1.6.0-1

3.2.1.6.0-2

3.2.1.6.0-3

3.2.1.6.0-4

3.2.1.6.1

3.2.1.6.1.1

3.2.1.6.1.1.0-1

3.2.1.6.1.1.0-2

3.2.1.6.1.1.0-3

3.2.1.6.1.1.0-4

3.2.1.6.1.1.0-5

3.2.1.6.1.2

3.2.1.6.1.2.0-1

3.2.1.6.1.2.0-2

3.2.1.6.1.3

3.2.1.6.1.3.0-1

3.2.1.6.1.4

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

The instrument contractor will provide an alignment drill template labeled with appropriate alignment, orientation, location reference information, and alignment cubes if necessary.

3.2.1.6 Alignment

The instrument contractor will measure the alignment between the sensor line-of-sight and the instrument alignment reference frame and deliver the results to the spacecraft contractor.

The spacecraft contractor is responsible for the alignment knowledge of the input axes of the spacecraft IRU with respect to the IRU reference frame.

The spacecraft contractor will document all alignment measurements in an alignment report.

The spacecraft and instrument contractors will negotiate and document in the ICD any relevant alignment requirements not specified in this document (GIRD).

3.2.1.6.1 Nadir Pointed Instrument Alignment

3.2.1.6.1.1 Alignment References

The instrument shall include a permanent alignment reference on the instrument sensor unit composed of a minimum 2.54 cm alignment cube with a flight cover and a mounting surface datum. The instrument alignment cube defines the instrument alignment reference frame.

The spacecraft inertial reference unit (IRU) shall include an alignment cube mounted with a flight cover on the IRU. This alignment cube defines the IRU reference frame. The IRU reference frame is the navigation reference frame of the spacecraft and is nominally parallel to the BRF.

The spacecraft IRU and instrument alignment cube pairs shall be viewable from two orthogonal directions.

The instrument contractor will document the location of all instrument optical alignment cubes in the IDD.

The instrument mounting frame is an orthogonal reference frame defined by the locations of the spacecraft side of the instrument mounting points. A definition of this frame will be documented in the ICD. The instrument mounting frame is nominally parallel to the BRF.

3.2.1.6.1.2 Alignment Responsibilities

The spacecraft contractor will align the instrument alignment reference frame to the spacecraft IRU reference frame.

The spacecraft contractor will measure the alignment between the instrument alignment reference frame and the spacecraft IRU reference frame.

3.2.1.6.1.3 Instrument Placement

The placement of the instrument alignment reference frame with respect to the spacecraft IRU reference frame shall be to within 0.25 degrees per axis, including variation over all launch and on-orbit environments.

3.2.1.6.1.4 Initial Alignment Knowledge

Page 11 of 56 Printed Wednesday, February 16, 2022

ID

GIRD138

GIRD139

GIRD140

GIRD141

GIRD142

GIRD143

GIRD144

GIRD145

GIRD146

GIRD147

GIRD148

GIRD149

GIRD150

GIRD151

GIRD152

GIRD153

GIRD154

Object Number

3.2.1.6.1.4.0-1

3.2.1.6.1.5

3.2.1.6.1.5.0-1

3.2.1.7

3.2.1.7.0-1

3.2.1.7.0-2

3.2.1.7.0-3

3.2.1.8

3.2.1.8.0-1

3.2.1.8.1

3.2.1.8.1.0-1

3.2.1.8.1.1

3.2.1.8.1.1.0-1

3.2.1.8.1.1.0-2

3.2.1.8.1.1.0-3

3.2.1.8.1.2

3.2.1.8.1.2.0-1

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

The prelaunch alignment knowledge of the instrument alignment reference frame with respect to the spacecraft IRU input axes shall be 300 microradians or better per axis.

3.2.1.6.1.5 Alignment Rate of Change

The rate of change of the alignment of the instrument mounting frame with respect to the spacecraft IRU input axes shall not exceed 100 microradians per hour per axis. This requirement includes on-orbit environments and spacecraft structural and thermal stability.

3.2.1.7 Instrument Access

The position of the instrument units on the spacecraft shall leave adequate clearance between the instrument and surrounding structures to provide access to instrument mounting hardware, access to instrument connectors, and space for instrument interfacing harness service loops.

Instrument access requirements will be documented in the ICD.

The instrument units shall mount to the satellite with only exterior access to the instrument unit.

3.2.1.8 Attitude and Disturbances for Nadir Pointed Instruments

The requirements in this section apply to nadir-pointing instruments while the instrument is on orbit and operating.

3.2.1.8.1 Spacecraft Attitude and Disturbances

The interface attitude error and disturbance limits include government-held reserve and all spacecraft errors, including orbit and attitude knowledge, attitude command error, and attitude control error with all instruments operating in normal operational mode.

3.2.1.8.1.1 Attitude Error

Attitude error is defined as the difference between the target attitude and the true attitude of the instrument mounting frame.

The total bias and quasi-static attitude error of the instrument mounting frame relative to the desired ORF-referenced attitude shall not exceed 4500 microradians, 3-sigma, per axis. Quasi-static error includes variation over timeframes longer than 24 hours.

The total diurnal and dynamic attitude error of the instrument mounting frame relative to the desired ORF-referenced attitude shall not exceed 325 microradians, 3-sigma, per axis. Diurnal error has a period of 24 hours. Dynamic error includes variation over timeframes shorter than 24 hours, typically much shorter.

3.2.1.8.1.2 Attitude Rate Error

The instrument shall meet all image performance requirements while amplitudes of the instrument mounting frame (IMF) angular rates per axis relative to the ORF and the total spacecraft angular rate data latency are less than the limits in Figure GIRD154.

Page 13 of 56 Printed Wednesday, February 16, 2022

ID

GIRD162

GIRD163

GIRD164

GIRD165

GIRD166

GIRD167

GIRD168

GIRD169

GIRD170

GIRD171

GIRD172

GIRD173

GIRD174

GIRD175

GIRD176

GIRD177

GIRD178

Object Number

3.2.2.1.1

3.2.2.1.1.0-1

3.2.2.1.2

3.2.2.1.2.0-1

3.2.2.1.3

3.2.2.1.3.0-1

3.2.2.2

3.2.2.2.0-1

3.2.2.2.0-2

3.2.2.2.0-3

3.2.2.2.0-4

3.2.2.3

3.2.2.3.1

3.2.2.3.1.0-1

3.2.2.3.1.0-2

3.2.2.3.2

3.2.2.3.2.0-1

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

3.2.2.1.1 Independent Unit - Net Heat Transfer

During operation, sensor units shall transfer less than 15.5 watts per meter squared averaged over its interface plane including radiation between adjacent instrument and spacecraft surfaces, conduction via the mechanical interface and conduction via the instrument harness.

3.2.2.1.2 Coupled Unit – Heat Transfer

The spacecraft shall provide a heat rejection path for thermally coupled units.

3.2.2.1.3 Coupled Unit - Heat Transfer Flux Density

Electronic units shall transfer less than 0.25 watts per square centimeter at any location of the interface plane.

3.2.2.2 Interface Temperatures

The instrument units shall operate with spacecraft interface temperatures defined in the operate columns of Table GIRD169.

Table GIRD169: Instrument operational and survival spacecraft interface temperatures operate survive min max min max units C C C C electronic 0 40 ‐10 50 sensor ‐15 35 ‐30 50

The instrument units shall survive with spacecraft interface temperatures defined in the survive columns of Table GIRD169.

The instrument units shall survive power ON at the minimum survival temperatures defined in Table GIRD169.

The spacecraft shall maintain the instrument interface temperatures within the operate range defined in Table GIRD169.

3.2.2.3 Temperature Monitoring

3.2.2.3.1 Mechanical Interface Temperature Monitoring

The instrument contractor will select a unit attachment point for interface temperature monitoring device and identify it on the IDD.

The spacecraft shall have a temperature sensor adjacent to this attachment point (on the spacecraft side) to serve as the interface temperature sensor.

3.2.2.3.2 Instrument Critical Temperatures

The instrument units shall contain critical temperature sensors to allow monitoring the thermal safety of the instrument while the instrument is OFF.

Page 14 of 56 Printed Wednesday, February 16, 2022

ID

GIRD179

GIRD180

GIRD181

GIRD182

GIRD183

GIRD184

GIRD185

GIRD186

GIRD187

GIRD188

GIRD189

GIRD190

GIRD191

GIRD192

GIRD193

GIRD194

GIRD195

GIRD196

GIRD197

GIRD198

Object Number

3.2.2.3.2.0-2

3.2.2.3.2.0-3

3.2.2.3.3

3.2.2.3.3.0-1

3.2.2.4

3.2.2.4.1

3.2.2.4.1.0-1

3.2.2.4.1.0-2

3.2.2.4.1.0-3

3.2.2.4.2

3.2.2.4.2.0-1

3.2.2.4.3

3.2.2.4.3.0-1

3.2.2.5

3.2.2.5.0-1

3.2.2.5.0-2

3.2.3

3.2.3.0-1

3.2.3.1

3.2.3.1.0-1

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

The spacecraft shall convey instrument critical temperatures via the spacecraft telemetry stream.

The instrument contractor will furnish temperature calibration coefficients for the critical temperature sensors and document them in the IDD.

3.2.2.3.3 Instrument Non-Critical Temperatures

The instrument shall report instrument non-critical temperatures in telemetry.

3.2.2.4 Thermal Interfaces

3.2.2.4.1 Mounting Details

The instrument shall be designed to perform during Spacecraft level Thermal Vacuum in the following two orientations:

a) Spacecraft +Y BRF axis aligned with gravity and pointed down.

b) Spacecraft –Z BRF axis aligned with gravity and pointed down.

The spacecraft contractor will select the thermal vacuum test orientation based on their test facilities.

The spacecraft contractor will document in the ICD properties of any thermally conductive or isolating materials used at the interface of the instrument unit.

3.2.2.4.2 Contact Area

Mounting contact area on the thermally coupled units and the spacecraft shall be unpainted.

3.2.2.4.3 Interstitial Materials

The spacecraft contractor will integrate the instrument units onto the spacecraft including application of any interstitial materials as conductive enhancements.

Selection and application of any interface materials require the concurrence of the instrument contractor and spacecraft contractor.

3.2.2.5 Multi-layer Insulation

Multi-layer insulation (MLI) shall have provisions for electrical grounding to prevent

ESD.

MLI vents shall be located and oriented consistent with observatory contamination requirements.

3.2.3 Instrument Electrical Power

All instrument electrical power interface requirements shall be specified at the instrument input power connectors.

3.2.3.1 Electrical Power Interfaces

The spacecraft shall supply functionally independent, primary and redundant operational power buses to each instrument for normal instrument operation.

Page 15 of 56 Printed Wednesday, February 16, 2022

ID

GIRD199

GIRD200

GIRD201

GIRD202

GIRD203

GIRD204

GIRD205

GIRD206

GIRD207

GIRD208

GIRD209

GIRD210

GIRD211

GIRD212

GIRD213

GIRD214

GIRD215

Object Number

3.2.3.1.0-2

3.2.3.1.0-3

3.2.3.1.0-4

3.2.3.1.0-5

3.2.3.1.0-6

3.2.3.1.0-7

3.2.3.1.0-8

3.2.3.1.0-9

3.2.3.1.0-10

3.2.3.1.0-11

3.2.3.2

3.2.3.2.1

3.2.3.2.1.0-1

3.2.3.2.2

3.2.3.2.2.1

3.2.3.2.2.1.1

3.2.3.2.2.1.1.0-1

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

The spacecraft shall supply either primary or redundant operational power buses for any instrument.

The instrument shall operate using either the primary or redundant operational power buses.

The instrument shall survive for an hour the application of power simultaneously on both primary and redundant operation buses.

The spacecraft shall supply functionally independent, primary and redundant survival power buses to each instrument to power the instrument survival heaters.

The spacecraft shall energize both primary and redundant survival power buses for all the instruments.

The thermally independent instrument units shall only utilize survival heater power for heaters and associated passive control circuitry which maintains the instrument above its minimum turn-on temperature.

The thermally independent instrument units shall maintain turn-on temperatures using either the primary or redundant survival heater buses.

The spacecraft power system shall accommodate instrument operational bus turn-on and peak survival bus loading simultaneously for each instrument.

The spacecraft power system shall accommodate the sequential turn-on/activation of all instruments.

Following the initial thermal transition from survival mode following instrument turn-on, the instrument shall not use power from the survival heater buses when operational power is active.

3.2.3.2 Power Specifications

3.2.3.2.1 Power Definitions

The following definitions shall be used when calculating average power, and maximum power values.

Average Power (Operational) - The total power into an instrument averaged over any 5 minute period.

Average Power (Survival) - The total power into an instrument averaged over any 72 minute period.

Maximum Power (Operational or Survival) - The total power into an instrument averaged over any 20 ms period.

3.2.3.2.2 Power Characteristics

3.2.3.2.2.1 Voltage

3.2.3.2.2.1.1 Instrument Voltage

The spacecraft shall supply DC voltage of 28 +/- 2.0 volts at the instrument operational power input connector for any condition of instrument load current including transients.

Page 18 of 56 Printed Wednesday, February 16, 2022

ID

GIRD238

GIRD239

GIRD240

GIRD241

GIRD242

GIRD243

GIRD245

GIRD246

GIRD247

GIRD248

GIRD249

GIRD250

Object Number

3.2.3.2.3.2

3.2.3.2.3.2.0-1

3.2.3.2.3.2.0-2

3.2.3.2.3.2.0-3

3.2.3.2.3.3

3.2.3.2.3.3.0-1

3.2.3.2.3.4

3.2.3.2.3.4.0-1

3.2.3.2.3.4.0-2

3.2.3.2.3.4.0-3

3.2.3.2.3.4.0-4

3.2.3.2.3.5

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

3.2.3.2.3.2 Operational Power ON/OFF Functionality

The spacecraft shall provide redundant commanding to switch instrument operational power ON and OFF to the instrument operational power input connector.

The spacecraft shall provide redundant instrument operational power ON and OFF status telemetry.

The spacecraft shall supply redundant switching of instrument operational power to the instrument operational power input connector.

3.2.3.2.3.3 Operational Power Overcurrent Protection

The spacecraft shall provide protection of the spacecraft power system by providing overcurrent protection on each instrument operational power connection.

Rationale: The current rating of the spacecraft provided operational power overcurrent devices for each instrument will be documented in the ICD.

3.2.3.2.3.4 Survival Heater Power Lines

The spacecraft shall supply single fault tolerant survival heater power distribution to the instrument for primary and redundant instrument survival heater power sources as specified in Figure GIRD246.

Figure GIRD246: Survival Heater Power Lines

Spacecraft Instrument

Survival Heater Power A1 (+)

Survival Heater Power A1 (-)

Side A1 Side A Power

Sw itc hin g

Cir cui t Pro tec tio n

Survival Heater Power B1 (+) Survival Heater Power B1 (-)

Side B1 Side B Power

Sw itc hin g

Cir cui t Pro tec tio n

The spacecraft shall provide each instrument with a maximum of five primary and five redundant instrument survival heater power sources.

The spacecraft shall independently sense and telemeter the instrument survival heater power current being supplied to each primary survival heater power source.

The spacecraft shall independently sense and telemeter the instrument survival heater power current being supplied to each redundant instrument survival heater power source.

3.2.3.2.3.5 Survival Heater Power On/Off Functionality

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ID

GIRD251

GIRD252

GIRD253

GIRD254

GIRD256

GIRD257

GIRD258

GIRD259

GIRD260

GIRD261

GIRD262

Object Number

3.2.3.2.3.5.0-1

3.2.3.2.3.5.0-2

3.2.3.2.3.6

3.2.3.2.3.6.0-1

3.2.3.2.3.7

3.2.3.2.3.7.0-1

3.2.3.2.3.7.0-2

3.2.3.2.3.7.0-3

3.2.4

3.2.4.1

3.2.4.1.0-1

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

The spacecraft shall provide redundant instrument survival heater power ON and OFF status telemetry.

The spacecraft shall supply independently commanded redundant switching of instrument survival heater power to the instrument survival heater power input connector.

3.2.3.2.3.6 Survival Heater Power Overcurrent Protection

The spacecraft shall provide protection of the spacecraft power system by providing overcurrent protection on each instrument survival heater power connection.

Rationale: The current rating of the spacecraft provided survival heater power overcurrent devices for each instrument will be documented in the ICD.

3.2.3.2.3.7 Abnormal Survival Power Voltage Limits

Under worst case fault transient conditions, the spacecraft shall limit the maximum instrument survival power voltage of nominal plus 10 volts for maximum duration of 50 milliseconds.

During a short-to-ground bus fault transient, the spacecraft shall control the instrument survival heater minimum voltage to greater than zero volts for a period of less than 1 second with a recovery to the nominal instrument survival heater voltage within 50 milliseconds.

Under failure mode conditions, the spacecraft shall limit the instrument survival power voltage to nominal plus 4 volts for one hour.

3.2.4 Instrument Electrical Power Grounding

3.2.4.1 Instrument Operational Power Grounding

The instrument electrical power grounding shall be in accordance with Figure

GIRD262.

Page 21 of 56 Printed Wednesday, February 16, 2022

ID

GIRD269

GIRD270

GIRD271

GIRD272

GIRD273

GIRD274

GIRD275

GIRD276

GIRD277

GIRD278

GIRD279

GIRD280

GIRD281

GIRD282

GIRD283

GIRD284

GIRD285

GIRD286

GIRD287

Object Number

3.2.4.2.0-2

3.2.4.2.0-3

3.2.4.2.0-4

3.2.4.2.0-5

3.2.4.2.0-6

3.2.4.3

3.2.4.3.0-1

3.2.4.3.0-2

3.2.4.3.0-3

3.2.4.4

3.2.4.4.1

3.2.4.4.1.1

3.2.4.4.1.1.0-1

3.2.4.4.1.2

3.2.4.4.1.2.0-1

3.2.4.4.1.3

3.2.4.4.1.3.0-1

3.2.4.4.2

3.2.4.4.2.1

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

The spacecraft shall control the DC resistance of each primary bus return connection to the single point ground to less than 2.5 milliohms.

Excluding current shunts, the total dc resistance between the spacecraft primary return(s) and the single point ground shall be less than 10.0 milliohms.

The spacecraft shall connect each instrument survival heater power return at spacecraft's primary bus unit connector to the spacecraft's primary bus return with a DC resistance of less than 2.5 milliohms.

The spacecraft shall supply a low impedance bond connection with a DC resistance of less than 2.5 milliohms between the single point ground and the spacecraft structure

The instrument shall isolate the instrument survival heater power returns from the instrument chassis with a DC resistance greater than 1 megohm.

3.2.4.3 Instrument Secondary Power Grounding

The instrument shall isolate the instrument secondary power returns from the instrument operational power and instrument survival heater power returns with a DC resistance greater than 1 megohm.

The instrument shall control the DC resistance between the instrument secondary returns to the instrument chassis to less than 2.5 milliohms.

The spacecraft shall supply a low impedance bond connection with a DC resistance of less than 2.5 milliohm between the spacecraft structure and instrument chassis mounted directly to the spacecraft structure.

3.2.4.4 Instrument Electrical Signal Grounding

3.2.4.4.1 Instrument Command Grounding

3.2.4.4.1.1 Instrument Pulse Command Grounding

The instrument shall isolate the instrument pulse command returns from the instrument operational power returns, instrument survival heater power returns, instrument secondary power returns and instrument serial command returns with a DC resistance greater than 1 megohm.

3.2.4.4.1.2 Instrument Serial Command Grounding

The instrument shall isolate the instrument serial command returns in accordance with the European Cooperation for Space Standardization (ECSS) ECSS-E-ST-50-12C Rev.1 (Space Wire) standard.

3.2.4.4.1.3 Instrument Electro-Explosive Device (EED) Command Grounding

The instrument shall isolate the instrument EED command returns from the instrument pulse command returns, instrument serial command returns, and instrument secondary power returns with a DC resistance greater than 1 megohm.

3.2.4.4.2 Instrument Telemetry Grounding

3.2.4.4.2.1 Instrument Analog Telemetry Grounding

Page 22 of 56 Printed Wednesday, February 16, 2022

ID

GIRD288

GIRD289

GIRD290

GIRD291

GIRD292

GIRD293

GIRD294

GIRD295

GIRD296

GIRD297

GIRD298

GIRD299

GIRD300

GIRD301

GIRD302

GIRD303

GIRD304

Object Number

3.2.4.4.2.1.0-1

3.2.4.4.2.2

3.2.4.4.2.2.0-1

3.2.4.5

3.2.4.5.1

3.2.4.5.1.0-1

3.2.4.5.1.0-2

3.2.4.5.2

3.2.4.5.2.0-1

3.2.4.5.2.0-2

3.2.4.5.2.0-3

3.2.5

3.2.5.0-1

3.2.5.1

3.2.5.1.0-1

3.2.5.2

3.2.5.2.0-1

418-XO-GIRD-0041, RM Version, Geostationary eXtended Observations (GeoXO) General Interface Requirements Document

(GIRD)

The instrument shall isolate low frequency analog telemetry returns with signal frequency characteristics below 1 MHz from the instrument operational power returns, instrument survival heater power returns, instrument pulse command returns, instrument serial command returns, instrument EED command returns, and serial telemetry returns with a DC resistance greater than 1 megohm.

3.2.4.4.2.2 Instrument Serial Telemetry Grounding

The instrument shall isolate the serial telemetry returns in accordance with the European Cooperation…