470-MWS-00435 SMBA Instrument PSD_RFI Release_V0.pdf

470-MWS-00435 Effective Date: October 14, 2022

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470-MWS-00435

Revision RFI DRAFT

Sounder for Microwave Brightness and

Analysis (SMBA) Instrument

Performance Specification Document (PSD)

Goddard Space Flight Center

Greenbelt, Maryland

JPSS Reviewed – Not Subject to Export Control

SMBA PSD 470-MWS-00435, RFI Release Draft Effective Date: October 14, 2022 ii

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Sounder for Microwave Brightness and Analysis Instrument

Performance Specification Document (PSD)

Review/Signature/Approval Page

Prepared By:

Robert Platt

SMBA Instrument Chief Engineer

NASA GSFC LEO Programs Division Code 470

Reviewed By:

Kenneth Yienger

LEOS Chief Engineer

Approved By:

Jessica Knizhnik

SMBA Instrument Manager

*** Signatures are available on-line at: https://......... ***

Goddard Space Flight Center

Greenbelt, Maryland iii

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Preface

This document is under LEOS Sounder Project configuration control. Once this document is approved, LEOS Sounder Project approved changes are handled in accordance with Class I and

Class II change control requirements as described in the LEOS Program Configuration

Management Procedures, and changes to this document shall be made by complete revision.

Any questions should be addressed to:

LEOS Program Configuration Management Office

NASA/GSFC

Code 470

Greenbelt, MD 20771 iv

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Change History Log v

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Deviations/Waivers Record

Section # /

Requireme nt

Deviation /

Waiver #

CCR # Date

Approved

Title Mission vi

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Table of TBDs/TBRs

Item No. Location Summary Individual/

Organization Due

Date vii

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TABLE OF CONTENTS

1 INTRODUCTION

1.1 Purpose

1.2 Document Scope

1.3 LEOS Sounder Mission Overview

1.4 Sounder for Microwave Brightness and Analysis Instrument Overview

1.5 Requirements Definitions

2 APPLICABLE/REFERENCE DOCUMENTS

2.1 Applicable Documents

2.2 Reference Documents

3 GENERAL REQUIREMENTS

3.1 On-Orbit Coordinate System

3.2 Mission Time Convention

3.3 Risk Classification and Mission Assurance Requirements

4 SMBA SCIENCE REQUIREMENTS

4.1 Science Performance Requirements

4.2 Hyperspectral Capability (TBD)

4.3 Calibration Accuracy

4.4 Temperature Sensitivity

4.5 Channel Dynamic Range

4.6 Channel Linearity

4.7 Noise Characteristics

4.7.1 Radio Frequency Interference

4.7.2 Striping (TBS)

4.7.3 Inter-channel Noise Correlation (TBS)

4.7.4 Noise Power Spectral Density (TBS)

4.8 Beam Characteristics

4.8.1 Channel Rejection

4.8.2 Gain

4.8.3 Scan Characteristics

4.9 Spectral Response Function

4.10 Calibration

5 LEOS SOUNDER SATELLITE-LEVEL REQUIREMENTS

5.1 Instrument Accommodations

5.2 Mission Orbit Requirements

5.3 Mission Lifetime, Commissioning, and Storage Requirements

5.4 Mission Data Requirements

5.4.1 Mission Data Geolocation Requirements

5.4.2 Instrument Pointing, Accuracy, and Stability Requirements

5.4.3 Instrument Timing Requirements

5.5 Mission Phases

5.5.1 Satellite Assembly, Integration and Test, and Ground Storage Phase

5.5.2 Pre-Launch/Launch Site Processing Phase

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5.5.3 Launch and Orbit Insertion Phase

5.5.4 Satellite Activation, Checkout, and Commissioning Phase

5.5.5 Mission Operations Phase

5.5.6 End-of-Life Decommissioning Phase

5.6 Instrument Functional Requirements

5.6.1 Typical Spacecraft Modes

5.6.1.1 Spacecraft Off Mode

5.6.1.2 Launch Mode Functional Requirements

5.6.1.3 Spacecraft Safe Modes

5.6.1.3.1 Earth-Pointing Safe Mode

5.6.1.3.2 Sun-Pointing Safe Mode

5.6.1.4 Spacecraft Engineering Mode

5.6.1.4.1 Orbit Adjust/Collision Avoidance

5.6.1.4.2 Instrument Calibration Maneuvers

5.6.1.5 Spacecraft Science Operations Mode

5.6.1.6 End-of-Mission Passivation Mode

5.6.2 Typical Instrument Modes

5.6.2.1 Instrument OFF Mode

5.6.2.2 Instrument Survival Mode

5.6.2.3 Instrument Safe Mode

5.6.2.4 Instrument Engineering Modes

5.6.2.4.1 Instrument Activation Mode

5.6.2.4.2 Instrument Diagnostic Mode

5.6.2.5 Instrument Operational Mode

5.6.3 Contingency Management

5.7 Instrument Design Requirements

5.7.1 Structural Requirements

5.7.2 Mechanism Design Requirements

5.7.2.1 Torque/Force Margins

5.7.2.2 Binding/Jamming/Seizing

5.7.2.2.1 Clearances

5.7.2.2.2 Tolerancing

5.7.2.2.3 Lubrication

5.7.2.3 Scan Motor

5.7.2.3.1 Scan Control Capability

5.7.2.3.2 Contingency Capability

5.7.2.4 Mechanism Performance and Strength Analysis

5.7.3 Electrical Systems Requirements

5.7.4 Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC)

Requirements

5.7.5 Thermal Control Requirements

5.7.6 Contamination Control Requirements

5.7.7 Instrument Flight Software Requirements

5.7.8 Instrument Simulator and Emulator Requirements

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6 SPACE ENVIRONMENT REQUIREMENTS

6.1 General Radiation

6.2 EMI/EMC - RF Environment

7 VERIFICATION REQUIREMENTS

7.1 Mission Requirements Verification

7.2 Electrical Functional Test Requirements

7.2.1 Electrical Interface Testing

7.2.2 Comprehensive Performance Tests (CPTs)

7.2.3 Limited Performance Tests (LPTs) and Aliveness Tests

7.2.4 LEOS Sounder Ground System Compatibility Tests (QCTs)

7.2.5 Flight Hardware Operating Time (Burn-In) and Failure Free Performance

7.3 Satellite-Level EMC/EMI Testing

7.3.1 Radiated Emissions (RE)

7.3.1.1 RE, Electric Field, Standard Bandwidth(s)

7.3.1.2 RE, Electric Field, Narrow Bandwidth(s)

7.3.1.3 Radiated Emissions, Spacecraft Transmitters

7.3.1.4 Radiated Emissions, SMBA Instrument Compatibility

7.3.2 Radiated Susceptibility (RS)

7.3.2.1 RS, Electric Field, Orbit and Launch Levels

7.3.2.2 RS, Electric Field, Satellite Transmitters

7.3.3 RF Airlink/Self-Compatibility Test

7.4 Structural and Mechanical Verification Requirements

7.4.1 Structural Loads Qualification

7.4.2 Acoustic Testing

7.4.3 Random Vibration Testing

7.4.3.1 Random Vibration After Rework

7.4.4 Sine Vibration Testing

7.4.5 Shock Testing

7.5 Mechanism and Deployment Verification

7.6 Thermal Vacuum Environmental Testing

7.6.1 Thermal Vacuum Cycling

7.6.2 Thermal Design Margin (Thermal Balance) Testing

7.6.3 Contamination/Bake-Out Requirements

8 REQUIREMENTS VERIFICATION MATRIX

8.1 General Verification Requirements

8.2 Verification Cross Reference

8.3 Definition of Verification Methods

8.3.1 Verification by Analysis

8.3.2 Verification by Inspection

8.3.3 Verification by Demonstration

8.3.4 Verification by Test

APPENDIX A - ACRONYMS/ABBREVIATIONS

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List of Figures

Figure 1.3-1 Notional LEOS Sounder Mission Architecture Figure 1.4-1 Sounder for Microwave Brightness and Analysis (SMBA) Instrument Figure 3.1-1 On-Orbit Coordinate Systems Figure 5.4-1 Data Transfer Interface

Figure 5.4.2-1 Pointing Terminology Figure 5.4.2-2 Analysis of Geolocation Knowledge Uncertainty at Nadir Figure 5.6.1-1 Typical Spacecraft Mode Transitions Figure 5.6.1.3.1-1 Typical Spacecraft Configuration for Earth-Pointing Safe Mode Figure 5.6.1.3.2-1 Typical Spacecraft Configuration for Sun-Pointing Safe Mode

Figure 5.6.1.4-1 Typical Spacecraft Configuration for Engineering Mode and Science

Operations Mode Figure 5.6.2-1 Typical Instrument Mode Transition Diagram

Figure 7.4.3.1-1 Minimum Workmanship Random Vibration Test Levels

Figure 7.4.5-1 Shock Response Spectrum (SRS) for Assessing Component Test Requirements

List of Tables

Table 4.0-1. Microwave Instrument Performance Capabilities Prioritization

Table 4.1-1: LEOS Program Microwave Sounder Baseline Requirements (TBS) Table 5.4.2-1 Mission End-to-End Pointing Requirements at Instrument LOS[1]

Table 5.6.1.4.2-1 Instrument Calibration Maneuver Requirements Table 5.6.2-1 Instrument Mode Characterization

Table 5.7.1-1 Flight Hardware Design/Analysis Factors of Safety Applied to Limit Loads [¹] [²]

Table 5.7.3-1 Component and Subsystem Level Test Applicability Matrix Table 5.7.7-1 Flight Processor Resource Utilization Limits Table 6.2-1 Radiated Susceptibility Levels Due to Factory/Transport, Launch Site, Launch

Vehicle, Ascent, and On-Orbit Phases Table 7.3-1 Satellite-Level EMI/EMC Test Applicability Matrix

Table 7.3.1.1-1 Unintentional Radiated Electric Field Emissions, 2 MHz to 18 GHz, Standard

MIL-STD-461G Bandwidths, Orbit Mode Table 7.3.1.1-2 Radiated Electric Field Emissions, 14 kHz to 18 GHz, Standard MIL-STD-

461G Bandwidths, Launch Mode, at Separation Plane Table 7.3.1.2-1 Unintentional Radiated Electric Field Emissions, Receiver Frequencies, Narrowband (notched) MIL-STD-461G Scans (Modified Bandwidths), Orbit Mode Table 7.3.1.2-2 Radiated Electric Field Emissions, Receiver Frequencies, Narrowband MIL-

STD-461G Scans (Modified Bandwidths), Launch Mode, at Separation Plane Table 7.3.1.4-1 Intentional and Unintentional Radiated Electric Field Emissions Limits at the

SMBA Instrument Interface, 18 to 200 GHz Table 7.3.1.4-2 SMBA Receive Sensitivity Table 7.3.2.2-1 Spacecraft Transmitter Frequency Susceptibility Test Levels

Table 7.4-1 Structural and Mechanical Verification Test Requirements Table 7.4.3.1-1 Component Minimum Workmanship Random Vibration Test Levels

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1 INTRODUCTION

1.1 Purpose

This Sounder for Microwave Brightness and Analysis (SMBA) Instrument Performance

Specification Document (PSD) specifies Level 3 functional, design, performance, integration, test, and delivery requirements for the Vendor-provided instrument.

1.2 Document Scope

This specification establishes Level 3 requirements for the Sounder for Microwave Brightness and Analysis (SMBA) Instrument. The scope of the PSD includes all functional, design, performance, integration, test, and delivery requirements for the Instrument, but does not include mission-specific accommodation and interface requirements for the instrument on the Spacecraft.

The Instrument Contractor is responsible for developing and maintaining a hierarchy of lower-tier specifications that derive and allocate requirements to subsystems and components.

1.3 LEOS Sounder Mission Overview

The Low Earth Orbit (LEO) Environmental Observational Systems (LEOS) Program provides a framework to provide global measurements of earth systems through satellites managed by

NOAA, and federal, commercial and international partners. These environmental measurements will be able to support a wide variety of atmospheric, terrestrial, marine and polar observations.

The data uses include the numerical weather prediction models, fire and flood models, atmospheric chemistry observations, and multiple land imagery products that have been a crucial piece of the NOAA strategic goal to create a “Weather Ready Nation” and which provide essential information to NOAA’s broader environmental stewardship mission. Following the recommendations from the 2017 NOAA Satellite Observation System Architecture Study

(NSOSA), the LEO Program intends to use a combination of small and medium satellite platforms in a disaggregated architecture. This approach will provide an efficient means of filling gaps quickly and taking advantage of emerging remote sensing technologies. To execute a disaggregated LEO architecture and other NSOSA recommendations, the LEO Program plans to:

• Use industry’s significant investment of funding, expertise, and innovation in space and space systems technology.

• Deploy NOAA observation system assets where and when they are most needed, enabled by shorter development timelines and more frequent launches.

• Leverage smaller instruments, satellites, and Venture Class launch vehicles; and

• Achieve greater agility to incorporate continuous advancement, using new business models and partners.

The LEOS Program will accomplish these goals by continuing to leverage the multi-decadal partnership between NOAA and NASA.

The LEOS Sounder Mission is an initial operational mission for the LEO Program featuring the development, integration, test, lunch, and science operations of the Sounder for Microwave

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Brightness and Analysis (SMBA) Instrument – a successor to the Advanced Technology

Microwave Sounder (ATMS) instrument, versions of which are on each of the JPSS satellites. It will allow the LEO Program to provide continuity with the existing JPSS-era microwave sounder measurements as well as leverage newer technological advances to advance the collection of microwave sounding data that is crucial to numerical weather prediction models.

Figure 1.3-1 Notional LEOS Sounder Mission Architecture

Utilizing elements and best practices of the commercial space industry to meet federal program level requirements, the LEOS Sounder Mission will demonstrate the LEO Program can provide operational microwave sounding observation capabilities with a small satellite that can be flexibly deployed to a variety of operational orbits. This first operational mission, consisting of four individual flight missions to two distinct sun synchronous orbits (local time of ascending nodes of 1330 and 1730), will demonstrate LEOS disaggregated mission portfolio that provides the program with the flexibility of placing microwave sounders in any operational orbit, at any time as the program needs to support microwave sounder needs.

The mission will also leverage mission assurance practices relative to established commercial

New Space missions and establish a referenceable knowledge base of rapid procurement

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practices that will benefit the future environmental observation missions planned in the high launch tempo LEOS Program.

The LEOS Sounder mission is Class C as per NPR 8705.4, which applies the appropriate NASA management controls, systems engineering processes, mission assurance requirements and risk management processes.

1.4 Sounder for Microwave Brightness and Analysis Instrument Overview

The Sounder for Microwave Brightness and Analysis (SMBA) instrument is the principal instrument aboard the LEOS Sounder satellite (see Figures 1.4-1). The Sounder for Microwave

Brightness and Analysis (SMBA) instrument (hereafter referred to as the ‘SMBA instrument' or simply the 'instrument'), collects microwave radiometric data that are used to calculate the vertical distribution of temperature, moisture, and pressure in the Earth’s atmosphere.

The instrument measures atmospheric radiances within the microwave range of approximately

20-300 GHz over a swath width of approximately 2,530 km from an altitude of 824 km. The instrument's notional layout showing spacecraft accommodation interfaces is depicted in Figure

1.4-1.

Instrument data are acquired continuously, stored on-board the satellite, and subsequently downlinked to a ground network for capture, preprocessing, and routing to meteorological centers.

Figure 1.4-1 Sounder for Microwave Brightness and Analysis (SMBA) Instrument

The instrument produces Raw Data Records (RDRs) in an uncalibrated form. Engineering, component telemetry, science data, radiometric, and spectral calibration data is provided to enable the RDRs to be calibrated and geolocated. In addition, diagnostic RDR data may be

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acquired for testing purposes. The data are sent to the NOAA Ground System where they are used as input to science algorithms that generate SDRs and EDRs.

The SMBA instrument system performance requirements are provided in subsequent sections.

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1.5 Requirements Definitions

Throughout this PSD:

a. Contractually imposed mandatory requirements are identified by "shall" statements with requirement identification numbers of the form MWPSD-XXXX. Any deviation from these requirements requires approval of the Government Contracting Officer.

b. Preferred good practices are identified by "should" statements. "Should" designates performance, which is requested, but not mandatory. Noncompliance of a "should" statement does not require Government approval but shall be addressed at the earliest applicable project milestone.

c. Permission is identified by "may" or "can" statements.

d. Expected outcome or action is identified by "will" statements.

e. The term "Spacecraft bus" refers to the LEOS Sounder Spacecraft without instruments.

f. The term “Satellite” refers to the LEOS Sounder Spacecraft bus integrated with the flight instrument(s). The term “Satellite” is equivalent to the term “Observatory” used in other NASA and LEOS Program documents.

g. The term "Spacecraft" may refer to the Spacecraft bus or the Satellite.

h. The term "Instrument Contractor" refers to the SMBA instrument contractor with whom the

Government has entered into a contract to execute the SMBA Instrument Statement of Work

(which is titled “Sounder for Microwave Brightness and Analysis (SMBA) Instrument Statement of Work (SOW) (470-MWS-00434)”) and satisfy the requirements of this PSD.

i. The term "Government" represents the appropriate NOAA and/or NASA LEOS Sounder management office or, where "the Government" is indicated as providing a function for or interface to the SMBA instrument Contractor, the function or interface may be provided by

Government support services contractors.

j. The term “TBR” (to be reviewed) means that the stated information will be reviewed for appropriateness jointly by the Contractor and the Government and the information may be changed prior to final definition by the Government during the course of the contract. The term

“TBD” (to be determined) indicates further research or analysis is needed to determine the information during the course of the contract. The term “TBS” (to be supplied) refers to a document that will be developed or provided during the course of the contract.

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2 APPLICABLE/REFERENCE DOCUMENTS

2.1 Applicable Documents

The Applicable Documents listed below are called out within individual requirements specified in the PSD. All or portions of these documents apply directly to the performance required and contain provisions that constitute requirements of this PSD. In the event of a conflict between the language in an Applicable Document and in this PSD, the PSD will govern.

Document Number

Revision Document Title

470-MWS-00435 * SMBA Instrument Mission Assurance Requirements 47x-000xx * LEOS Sounder Spacecraft to SMBA Instrument Interface Control

Document 47x-000xx * LEOS Sounder Spacecraft to SMBA Instrument Mechanical

Interface Control Document 470-REF-00034 * Radiation Environment for the LEOS Sounder Mission GSFC-STD-7000 B General Environmental Verification Standard (GEVS) for GSFC

Flight Programs and Projects ISO 14644-1 May 1, 1999 Cleanrooms and Associated Control Environments

MIL-STD-461C C

August 4, 1986 Electromagnetic Emission and Susceptibility Requirements for the Control of Electromagnetic Interference (EMI), Revision C

(August 4, 1986)

MIL-STD-461G G

December 11, Requirements for the Control of Electromagnetic Interference

Characteristics of Subsystems and Equipment, Revision G

(December 11, 2015) MIL-STD-462 Rev -

Notice 2 from May 1, 1970

Measurement of Electromagnetic Interference Characteristics

(Notice 2)

NASA-STD-5001 A Structural Design and Test Factors of Safety for Spaceflight

Hardware NASA-STD-8719.24 Initial with

Change 1, Annex with Change 2

Jun 2012

NASA ELV Payload Safety Requirements

NPR 8715.6 A with Change 1 May 2009

NASA Procedural Requirements for Limiting Orbital Debris

ORDEM Version 3.2 Orbital Debris Engineering Model MEM Version 3.0 Meteoroid Environment Model

* See Attachment TBS of the contract DO, Applicable Documents List, for the current revision

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2.2 Reference Documents

The Reference Documents listed below are referred to within the PSD and contain information relating to the work required. The documents do not contain provisions that constitute requirements of this PSD, but rather serve to amplify or clarify the requirements.

Document Number Revision Document Title 47x-00xxx * LEOS Sounder Satellite Statement of Work (SOW) 47x-00xxx * LEOS Sounder Satellite Contract Data Requirements List (CDRL) 472-00228 * JPSS Flight Project Contamination Control Plan

ASTM E595 Revision dated December 1, Standard Test Method for Total Mass Loss and Collected Volatile

Condensable Materials from Outgassing in a Vacuum Environment

IEST-STD-CC1246 E Product Cleanliness Levels and Contamination Control Program JSC-CR-06-070 August 2006 Space Vehicle RF Environments NPR 8705.4 Revalidated with Change 2 June 12, 2013

Risk Classification for NASA Payloads http://outgassing.nasa.gov Outgassing Data for Selecting Spacecraft Materials

* See Attachment TBS of the contract DO, Applicable Documents List, for the current revision http://outgassing.nasa.gov/

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3 GENERAL REQUIREMENTS

3.1 On-Orbit Coordinate System

LEOS Sounder's on-orbit coordinate system uses a right-hand, orthogonal, body-fixed XYZ coordinate system as follows (see Figure 3.1-1): the +Z-axis is downward towards geodetic nadir, the Y-axis is along the orbit normal plane (+Y is opposite the orbital angular momentum), and the X-axis is along the Spacecraft velocity vector (+X toward the direction of Spacecraft travel).

Figure 3.1-1 On-Orbit Coordinate Systems

LEOS Sounder uses J2000-referenced orbital elements for attitude knowledge and the WGS84 geodetic reference system for environmental data geolocation.

The Instrument should use the international system of units, Système Internationale (SI), unless precluded by design or manufacturing heritage. All interface documents should provide units in

SI and English. The primary (as-designed) units should be displayed above the converted units with the latter in parentheses.

3.2 Mission Time Convention

MWPSD-1 The Instrument shall time stamp packets in the secondary header using

Coordinated Universal Time (UTC), including the leap-second convention, also known as CCSDS Day Segmented Time Code, for all instrument telemetry while the instrument processor is running.

Note: Telemetry frames that are generated by hardware during ascent or processor down time may format the time stamp using CCSDS Unsegmented Time Code.

3.3 Risk Classification and Mission Assurance Requirements

The SMBA Instrument risk classification is Class C, as per NPR 8705.4, Risk Classification for

NASA Payloads.

MWPSD-2 The Instrument Provider shall comply with SMBA Instrument Mission

Assurance Requirements (470-MWS-00435).

Safety design requirements and requirements for the control of catastrophic and critical failures are contained in SMBA Instrument Mission Assurance Requirements (470-MWS-00435).

The Instrument and its ground support equipment used at the launch site comply with the NASA-

STD-8719.24 NASA ELV Payload Safety Requirements or other applicable range safety documentation contained in SMBA Instrument Mission Assurance Requirements (470-MWS-

00435).

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4 SMBA SCIENCE REQUIREMENTS

To provide guidance on microwave sounder instrument performance capabilities, Table 4.0-1 details the relative prioritization of the various performance factors associated with the next generation microwave instrument.

Table 4.0-1. Microwave Instrument Performance Capabilities Prioritization1 Factor

Order Performance Factor Baseline Target Aspirational Target

Channels for direct

Temperature Sounding

13 Channels around 50-60 GHz and

7 channels around 118 GHz line > 20 channels around 50-60 GHz and

> 10 channels around 118 GHz line

Channels for direct

Moisture sounding 5 Channels or more around 183 GHz 10 Channels or more around 183 GHz

Window channels;

channels for cloud, precipitation, ice detection for direct all-sky assimilation and

NWP QC

Channels at 23.8, 31.4, 88.2.

One channel at 165.5 (TBR) and/or

229 (TBR) GHz channels

Baseline Targets and:

a) At least 4 channels at low frequencies (priority order) (i.e. 22-23

GHz(a), 31-37 GHz(b), 89 GHz(c) and

18 GHz (d))

b) 200-325 GHz channels for cloud/precipitation detection and surface signal distinction

Spatial coverage

(daily) 95% Global Coverage 100% Global Coverage

Noise Level (NEDT) for Temperature sounding channels

See Table 4.1-1 See Table 4.1-1

Noise level (NEDT) for Moisture sounding channels

See Table 4.1-1 See Table 4.1-1

Spatial horizontal resolution (nadir)

32 km (T)

16 km (q)

8 km (T)

5 km (q)

8 Spatial sampling Contiguous footprints (or better)

Oversampling (Spatial Nyquist sampling at a minimum) to enable higher spatial resolution

9 Scan geometry Cross track or conical

10 Polarization Single linear polarization

Baseline and:

Dual polarization (vertical/horizontal) for window channels below 50 GHz

ATMS Channels

Continuity Yes, for similar channels

12 Calibration accuracy See Table 4.1-1 Less than values in Table 4.1-1

1 Systems performance Assessment Team (SAT), Boukabara, S.(chair), Gallagher, F.(co-chair). [Scientific Guidance for potential study and design of Microwave Sounder (for SounderSat and GEO-XO)]. Retrieved from

NOAA/NESDIS Center for Satellite Applications and Research. September 17, 2020.

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4.1 Science Performance Requirements

Table 4.1-1: LEOS Program Microwave Sounder Baseline Requirements (TBS)

Priority Center Frequency (1) (GHz)

Center

Frequency

Stability (2)

(MHz)

Maximum

Bandwidth (3)

(GHz)

Calibration

Accuracy

(K)

Temperature Sensitivity

(No Greater than) NedT @300K (K)

Baseline Aspirational

(III) (IV) 23.8 5 0.27 0.5 0.24 0.22

(III) (IV) 31.4 5 0.18 0.5 0.30 0.28

(I)

(IV)

50.3 4 0.18 0.5 0.33 0.30

51.76 4 0.4 0.5 0.22 0.20

52.8 4 0.4 0.5 0.22 0.20

53.596 ± 0.115 3 0.17 0.5 0.24 0.22

54.4 2 0.4 0.5 0.22 0.20

54.94 3 0.4 0.5 0.22 0.20

55.5 3 0.33 0.5 0.25 0.22

57.290344 0.3 0.33 0.5 0.35 0.30

57.290344 ± 0.217 0.4 0.078 0.5 0.50 0.45

57.290344 ± 0.3222 ± 0.048 0.9 0.036 0.5 0.55 0.50

57.290344 ± 0.322 ± 0.022 0.4 0.016 0.5 0.80 0.75

57.290344 ± 0.322 ± 0.010 0.4 0.008 0.5 1.10 1.00

57.290344 ± 0.3222 ± 0.0045 0.5 0.003 0.5 1.80 1.60

(III) (IV) 88.2 18 2 0.5 0.20 0.15

(I)

114.50 1 1 0.5 0.40 0.30

115.95 1 0.8 0.5 0.40 0.30

116.65 1 0.6 0.5 0.40 0.03

117.25 1 0.6 0.5 0.40 0.30

117.80 1 0.5 0.5 0.40 0.30

118.24 1 0.38 0.5 0.50 0.40

118.58 1 0.30 0.5 0.60 0.50

(III) 165.5 (TBR) 22 3 0.4 0.34 0.30

(II)

(IV)

183.31 ± 7 14 2 0.4 0.30 0.26

183.31 ± 4.5 14 2 0.4 0.30 0.26

183.31 ± 3 16 1 0.4 0.40 0.36

183.31 ± 1.8 10 1 0.4 0.40 0.36

183.31 ± 1 9 0.5 0.4 0.55 0.50

(III) 229 (TBR) 22 2 0.5 0.40 0.36

(1) Number of passbands per channel, listed in “Center Frequency” column, is maximum allowed. Fewer passbands may be used, provided the Temperature Sensitivity requirements are met. For example, Table 4.1-1 lists two passbands centered at (183.31 +

7) = 190.31 GHz and (183.31-7) = 176.31 GHz. The channel may be implemented using only one of these passbands, provided the temperature sensitivity value of no greater than 0.3 K is achieved.

(2) Channel center frequency stability is defined as the maximum deviation from the channel center frequency for both long-term and short-term periods over the operational life of the instrument.

(3) Channel bandwidth is defined as the spectral width between the half-power points per passband.

(I) Performance Capability Priority 1: Temperature Sounding

(II) Performance Capability Priority 2: Moisture Sounding (III) Performance Capability Priority 3: Additional Channels

(IV) Performance Capability Priority 11: ATMS Channel Continuity

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MWPSD-3 SMBA Instrument shall provide the channels at the nominal center frequencies identified in Table 4.1-1.

MWPSD-4 The center frequency stability of the channels shall less than or equal to the values listed in Table 4.1-1.

MWPSD-5 The bandwidths of the channels shall be less than or equal to the values listed in Table 4.1-1.

4.2 Hyperspectral Capability (TBD)

Hyperspectral capability indicates an increased number of channels for a given frequency range.

MWPSD-6 Hyperspectral capability shall be provided for TBD frequency ranges.

MWPSD-7 NEDT performance of a hyperspectral design shall be similar to that of a non-hyperspectral design in the same frequency range.

4.3 Calibration Accuracy

Calibration accuracy is defined as the difference (error) between the brightness temperature inferred from the microwave radiometer (referred to the antenna collecting aperture) and the actual brightness temperature of a calibration reference. Calibration accuracy is the average error over a time scale longer than 24 hours.

Note:

1) A calibration reference is defined as an element that provides a signal that corresponds to a known brightness temperature. It can be a physical thing (like a blackbody; ex: on-board target or cold space). A noise diode is also an example of a reference.

2) Traditional radiometers have used two-point calibration methodology: cold space for the cold reference temperature and an on-board target for the warm reference temperature. The instrument design is not constrained to this methodology or calibration reference types. Other types of calibration references exist such as noise diodes and cold FETs.

3) Proposed references that are also standards (in the National Institute of Standards and

Technology (NIST) sense) must include a description of the traceability plan that enables them to be a standard, along with an estimate of the (absolute) accuracy.

Overall accuracy includes uncertainties due to (1) errors contained in the laboratory tests and the test equipment, (2) the transition from the laboratory simulated cold calibration reference to the on-orbit cold calibration reference, and (3) emissions from the spacecraft and other instruments intercepting the near fields of the radiometer antenna(s).

Note: Nonlinearity is an important parameter because it is used to calculate the quadratic correction for nonlinearity in the JPSS Temperature Data Record algorithm (ground processing). Therefore, Check the JPSS/LEO MIS Server at https://jpssmis.gsfc.nasa.gov/frontmenu_dsp.cfm to verify that this is the correct version prior to use.

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nonlinearity does not contribute to on-orbit calibration accuracy. However, the residual nonlinearity is a contributor to calibration accuracy.

MWPSD-8 The calibration accuracy of the channels shall be less than or equal to the values listed in Table 4.1-1.

MWPSD-9 Overall accuracy shall include uncertainties caused by time-dependent degradation of the reference targets.

MWPSD-10 Calibration accuracy predictions shall be computed as the sum of static (bias) errors and the root-sum-square of the standard deviations of dynamic (time-variable) errors, for worst case environmental conditions.

4.4 Temperature Sensitivity

Temperature sensitivity (noise equivalent delta temperature or NEdT) is defined as the standard deviation of the radiometer output in kelvins (K) brightness temperature incident at the antenna collecting aperture, when the antenna is viewing a 300 K uniform and stable target.

MWPSD-11 The temperature sensitivity of the channels shall be less than or equal to the baseline values listed in Table 4.1-1.

Note: Table 4.1-1 contains “Aspirational” values for temperature sensitivity. It is encouraged, but not required, to achieve the aspirational performance values.

MWPSD-12 The brightness temperature measurement of an Earth scene or calibration reference shall be independent of any previous measurements.

4.5 Channel Dynamic Range

MWPSD-13 The dynamic range of the radiometer system shall be sufficient to cover the expected range of Earth scene brightness temperatures as well as calibration references.

4.6 Channel Linearity

Nonlinearity is usually defined as the departure from the expected response of an ideal linear radiometer. The “residual nonlinearity” is defined as the residual error after applying a correction for the nonlinearity

MWPSD-14 The residual nonlinearity shall be less than or equal to 0.1 K for all channels.

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4.7 Noise Characteristics

4.7.1 Radio Frequency Interference

MWPSD-15 Detection of Radio Frequency Interference (RFI) by man-made signals that impact operational data products, shall be incorporated in the instrument design.

4.7.2 Striping (TBS)

Differences in the along-scan vs. along-track noise characteristics can lead to undesirable linear artifacts in images – i.e., striping.

MWPSD-TBS TBS

Note: Instrument provider to propose striping requirement (or multiple requirements).

4.7.3 Inter-channel Noise Correlation (TBS)

Typically, inter-channel noise correlation is measured by correlating the noise signal in one channel to the concurrent noise signal in another channel while viewing the same Earth scene or calibration reference.

MWPSD-TBS The noise correlation coefficient for any two channels shall be less than or equal to TBS.

Note: Request that the instrument vendor suggest an inter-channel noise correlation requirement.

4.7.4 Noise Power Spectral Density (TBS)

The noise power spectral density is an important characteristic of all radiometer channels relating quantities like NEDT, 1/f noise, gain variations, and striping. There are different ways that one might specify requirements related to noise power spectral density. Request that the instrument vendor suggest noise power spectral density requirements.

MWPSD-TBS TBS

Note: Instrument provider to propose striping requirement (or multiple requirements).

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4.8 Beam Characteristics

Each channel of the instrument is considered to form a beam. In the following sections, if only one beam is discussed it is inferred to represent any and all beams.

The term “Beam Position” means the position of a “Beam-Center,” which is defined as the position of the beam (electrical boresight) at the mid-point of the integration time.

Beamwidth is defined as the width between the half-power points. The beam electrical boresight is defined as the mid-point between the half-power points of the instantaneous antenna pattern.

MWPSD-16 The beamwidth in any plane containing the main beam axis (electrical boresight axis) shall be within plus or minus 10% of the nominal beam width.

MWPSD-17 Instrument antenna beam efficiency shall be no less than 95.0% at all frequencies and all beam positions.

MWPSD-18 Antenna characterization measurements/patterns shall be provided for each instrument channel.

MWPSD-19 All main beam axes of the instrument shall be coincidental (i.e., they will be pointing in the same direction, subject to the pointing accuracy requirements) at the same time for any given beam position.

4.8.1 Channel Rejection

MWPSD-20 Each channel shall have a gain that is no greater than 40 dB below the band-center value for all frequencies outside of a band ±0.70 times the specified half-power bandwidths.

MWPSD-21 All channels that use upper and lower mixer sideband signals shall employ stop-bands to reduce local oscillator noise to levels compatible with meeting the sensitivity and the calibration accuracy requirements.

4.8.2 Gain

Passband gain is defined as the overall gain of the instrument from the antenna aperture to the instrument output, averaged over the passband bandwidth.

MWPSD-22 The gains of all passbands within any one channel shall be within ±1 dB.

MWPSD-23 The band center gain of each passband shall vary no more than ±2 dB over the operating temperature range and life of the instrument.

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4.8.3 Scan Characteristics

MWPSD-24 The instrument shall scan and position the sensor boresight to enable measurement of scene radiance at specified locations.

MWPSD-25 The instrument shall synchronize its scan start time with a timing signal it receives from the spacecraft command and telemetry (C&T) bus.

MWPSD-26 The time offset from the rising edge of the spacecraft timing signal to the start of beam position number one of the instrument scan shall have an accuracy of ±1 msec.

4.9 Spectral Response Function

The Spectral Response Function (SRF) is defined as the one-to-one mapping between the end-to-end gain values (from the antenna aperture through the detector output) and the RF frequencies of radiation relevant to each channel. SRF’s are created via a combination of measurement and analysis.

For a channel having multiple pass bands, the SRF of each passband is unique and must be independently ascertained.

SRFs are used to generate: (1) Band absorption coefficients for radiative transfer models used by environmental retrievals algorithms and numerical weather prediction (NWP) models. NWP models continue to require more accurate SRF measurements. (2) Band conversion coefficients in the SDR algorithm that calculate warm/cold target radiance from their physical temperatures and earth spectral brightness temperature from earth radiance.

MWPSD-27 Through a combination of measurement and analysis, SRFs shall be provided for each channel of the SMBA instrument.

4.10 Calibration

MWPSD-28 The SMBA Instrument shall perform in-flight calibration for all channels.

MWPSD-29 Ground calibration testing and analyses shall be performed to demonstrate that the instrument, when used in its orbital configuration, complies with the accuracy requirements.

MWPSD-30 The SMBA instrument shall be designed such that the ground calibration needs to be performed only once for each delivered instrument. No ground calibration shall be required after prolonged storage before launch.

Note: Requirements MWPSD-31 through MWPSD-49 are reserved for future instrument science requirements pertaining to specific implementation approaches.

MWPSD-31 RESERVED

to

MWPSD-49 RESERVED

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5 LEOS SOUNDER SATELLITE-LEVEL REQUIREMENTS

The following paragraphs contain requirements extracted from the LEOS Sounder Program-level requirements documentation and are directly traceable to NOAA's Mission Requirements.

5.1 Instrument Accommodations

MWPSD-50 The Instrument shall comply with the accommodation requirements, in accordance with the requirements delineated herein and the Spacecraft-to-

SMBA Instrument Interface Control Document (ICD) (47x-000xx).

MWPSD-51 The Instrument shall define/maintain static and dynamic clearances to the respective instrument envelope(s), define/maintain the instrument operational, calibration, and thermal field-of-views, and define integration and test target accommodations in the Spacecraft-to-SMBA Mechanical ICD

(MICD) (47x-000xx).

MWPSD-52 The initial mass allocation of the SMBA instrument will be 125 kg (TBS) inclusive of instrument margin. The specific mass properties shall be specified in the Spacecraft-to-SMBA Instrument Interface Control

Documents (ICD) (47x-000xx).

MWPSD-53 The Instrument shall be compliant with the expendable launch vehicle (ELV) mechanical, electrical, and environmental requirements and constraints delineated herein and the specified in the Spacecraft-to-SMBA Instrument

Interface Control Documents (ICD) (47x-000xx).

MWPSD-54 The initial orbital average power (OAP) allocation of the SMBA Instrument will be 150W (TBS) inclusive of instrument margin. The specific OAP, survival, and peak power needs (inclusive of margin) of the instrument shall be specified in the Spacecraft-to-SMBA Instrument Interface Control

MWPSD-55 While an adiabatic interface is preferred, the initial allowable heat transfer to the spacecraft during science operations is NTE 100 W at an interface temperature of 15 °C. The specific thermal interface needs (inclusive of margin) of the instrument shall be specified in the Spacecraft-to-SMBA

Instrument Interface Control Documents (ICD) (47x-000xx).

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MWPSD-56 The Instrument shall not exceed an uncompensated momentum contribution of

0.5 N-m-sec per axis (TBS). The specific level of on-orbit disturbances induced to the spacecraft across the instrument-to-spacecraft mounting interface shall be specified in the Spacecraft-to-SMBA Instrument Interface

Control Documents (ICD) (47x-000xx).

5.2 Mission Orbit Requirements

MWPSD-57 The Instrument shall operate for the mission lifetime in a polar sun-synchronous orbit with the following characteristics:

Nominal Altitude: 824 km +/- 17 km

Nominal Inclination: 98.71 degrees +/- 0.10 degrees

Ground Track Repeatability Accuracy: +/- 20 km at the equator

Ground Track Repeat Cycle: 16 days

MWPSD-58 The Instrument shall operate for the mission lifetime in the polar sun-synchronous orbit defined above when deployed/maintained orbit in either of the following local time of the ascending nodes (LTANs):

Nominal Ascending Equator Crossing Time: 1330 (local time) +/- 10 minutes or

Nominal Ascending Equator Crossing Time: 1730 (local time) +/- 10 minutes

5.3 Mission Lifetime, Commissioning, and Storage Requirements

MWPSD-59 The Instrument shall be designed for a design mission lifetime of 5 years from completion of on-orbit commissioning.

MWPSD-60 The Instrument shall be capable of a 10-year ground storage period that includes routine maintenance and monitoring activities to ensure no loss of functional capabilities.

MWPSD-61 The Instrument shall be capable of being placed in a ground storage state that requires minimal intervention by personnel for up to 30-day periods.

5.4 Mission Data Requirements

The Spacecraft C&DH subsystem collects instrument health & status telemetry, instrument memory dump, and mission data packets through the command & data interface. The C&DH subsystem multiplexes these packets and attaches appropriate protocol for downlink and storage.

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The following functions (see Figure 4.4.1-1), where appropriate, are to be provided between the

Spacecraft and the instruments.

a. Spacecraft-to-instrument transfers consisting of real-time ground commands, stored commands, memory loads, state of health indications, and auxiliary data (e.g., time code).

b. Instrument-to-Spacecraft transfers consisting of mission data (including auxiliary data received from the Spacecraft), instrument health and status telemetry, instrument transition to Safe Mode indicator, instrument diagnostic data, memory dumps, and

Survival Mode temperatures (not part of the data bus).

Figure 5.4-1 Data Transfer Interface

The instrument average data rate is defined to be the total data for one orbit divided by the orbit period. The instrument peak data rate is defined as the maximum data volume divided by the collection period.

MWPSD-62 The Instrument average/peak data rates per instrument mode shall be specified in the Spacecraft-to-SMBA Instrument Interface Control

MWPSD-63 Receipt of individual instrument commands shall be verifiable via Spacecraft health and status telemetry.

5.4.1 Mission Data Geolocation Requirements

MWPSD-64 The known geolocation of the SMBA instrument boresight, referenced to the center of the effective field of view for any channel, shall be within 1.50 km

(3 sigma), at nadir, on the WGS84 reference ellipsoid, at any time during nominal operations.

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5.4.2 Instrument Pointing, Accuracy, and Stability Requirements

Figure 5.4.2-1 Pointing Terminology

Pointing terminology definitions are illustrated in Figure 5.4.2-1 and are defined as follows for each spacecraft axis:

• Pointing Knowledge - The angle between the actual pointing direction and the estimated pointing direction.

• Pointing Accuracy (Pointing Control) - The angle between the actual pointing direction and the desired pointing direction.

• Pointing Stability - The peak-to-peak variation in the actual pointing direction over a time interval.

• Accuracy and Knowledge terms consist of three error categories:

i. Bias: errors that remain constant over the duration of the mission.

ii. Drift: A long term variation of pointing direction.

iii. Jitter: A short term variation of the pointing direction.

• Static Errors - Errors that stay constant over mission time. Bias errors are static errors.

• Dynamic Errors - Errors that vary over time. Drift and Jitter errors are dynamic errors.

• Pointing Stability is due to dynamic error sources Drift and Jitter.

• 3 Sigma - A set of values is considered to meet a 3-sigma requirement if no fewer than

99.73% of the values are within the specified limits of the requirement.

All components…