LRO System Requirements Review Diviner Lunar Radiometer Experiment Requirements

LRO System Requirements ReviewDiviner Lunar Radiometer Experiment

Requirements

Marc C. Foote Lunar Diviner System Engineer

Jet Propulsion Laboratory

08 - 2

DLRE Organization Chart

08 - 3

Science Overview / Theory of Operation

Measurement Goals:

• Map Global Day/Night Surface Temperatures

• Map Global Solar Illumination

• Characterize Thermal Environments for Habitability

• Determine Rock Abundances at Landing Sites

• Identify Potential Polar Ice Reservoirs

• Map Silicate Mineralogy to Locate Ilmenite – Easily Broken Down into Titanium, Iron, and Oxygen

Measurement Approach:• Minor changes from heritage Mars Climate Sounder instrument (MRO)• 9-channel radiometric pushbroom mapper (0.3 to 200 micron wavelength range)• 300m spatial resolution• Internal blackbody and solar calibration targets

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HeritageArea Heritage from

Mars Climate Sounder

Changes from Mars Climate Sounder

Mechanical All

Electronic All electronic hardware in instrument.

Addition of external interface box with processor, FPGA, memory, and 1553 interface.

Program for FPGA in instrument.

Software Most of software for processor in instrument.

Minor changes to software for processor in instrument.

Software for new interface box – bundles data and interfaces with spacecraft.

Thermal All except noted under changes. Addition of extra blankets or shields in nadir region to mitigate warmer thermal environment

Optical All except spectral filters. Spectral filters.

I&T Test Equipment

Most of assembly procedures

Most of test procedures

Assembly and test of external interface box.

Functional Requirements

Document format.

Majority of requirements.

Spectral bandpass requirements.

Integration time requirement.

Spacecraft interface requirements.

08 - 5

Instrument Documents

• LRO Requirements Document; ESMD-RLEP-0010

– LRO Mission Requirements Document; 431-RQMT-00004

• LRO Technical Resource Allocations; 431-RQMT-000112

• Instrument Payload Assurance Implementation Plan

• DLRE Mechanical Interface Control Document 431-ICD-000086

• DLRE Electrical Interface Control Document 431-ICD-000095

• DLRE Data Interface Control Document 431-ICD-000105

• DLRE Thermal Interface Control Document 431-ICD-000116

– Instrument Requirements Documents

• Diviner Lunar Radiometer Experiment (DLRE) Instrument Performance Requirements Document (IPR) JPL-D-32399

• Diviner Lunar Radiometer Experiment (DLRE) Data Product Specification Document (DPS) JPL-D-32400

• Diviner Lunar Radiometer Experiment (DLRE) Functional Requirements Document (FRD) JPL-D-32375

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Mission Level RequirementsESMD-RLEP-0010

LRO

Req.Level 1: Requirements

LRO Mission Requirement Required Data Products

RLEP-LRO-M50

The LRO shall obtain temperature mapping from 40 - 300K in the Moon’s polar regions (within 5 degrees of the poles) to 300m spatial resolution and 5K precision for a full lunar cycle.

Direct temperature mapping at ~300M spatial resolution with minimum detectable temperature of 24K over an entire diurnal cycle enables the detection and characterization of cold traps in polar shadowed regions.

RLEP-LRO-M80

The LRO shall assess meter-scale features of the lunar surface to enable safety analysis for potential lunar landing sites over targeted areas of 100km^2 per the LRO Landing Site Target Specification Document.

Determine rock abundances of up to 50 selected potential landing sites.

RLEP-LRO-M90

The LRO shall characterize the Moon’s polar region (within 5 degrees of the poles) illumination environment at relevant temporal scales (i.e., typically that of hours) to a 100m spatial resolution and 5 hour average temporal resolution.

Provide illumination map derived from Illumination and Scattering Model (Includes slopes, raytraced shadows, and full 3D radiosity solution for scattered solar and infrared radiation), and 1-D lunar thermal model.

RLEP-LRO-M100

The LRO shall obtain high spatial resolution global resources assessment including elemental composition, mineralogy, and regolith characteristics to a 20% accuracy and a 5km resolution.

Fine-component thermal inertia and lambert albedo from surface temperature, solar reflectance and topography

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Instrument System Level Requirements (1)

Level 1 Req.

Instrument Level 2:

DLRE Instrument Performance Requirements JPL-D-32399

Concept/Realizability/

Comment

Level 2 Req.

NumberDIVINER Instrument Measurement Requirement

M50-DIVINER

DLRE-L2-1 To achieve 300m spatial resolution from the LRO mapping orbit (50 km nominal altitude), Diviner's IFOV must not exceed 6 mrad cross-track and 6 mrad along-track.

Detector and optics sized to 6mrad

M50-DIVINER

DLRE-L2-2 To achieve 300M spatial resolution from the LRO mapping orbit (50km nominal altitude) along-track, Diviner must have an integration period of less than 180 ms.

128 ms integration time

M50-DIVINER

DLRE-L2-3 To achieve 24k minimum detectable temperature, Diviner must achieve a SNR ≥1 in at least one spectral channel when viewing a blackbody source at 24K.

100-200μm band with high sensitivity

M50-DIVINER

DLRE-L2-4 To map temperatures between 40 and 300K in the polar region and characterize cold traps, Diviner must have multiple spectral bands spanning at least 15-150 μm.

Four pushbroom arrays with passbands 12.5-25μm, 25-50μm, 50-100μm, 100-200μm

M50-DIVINER

DLRE-L2-5 To map temperatures between 40 and 300K in the polar region and characterize cold traps, Diviner must measure surface brightness temperature with an accuracy of 5K from 40-55K, 2.5K from 55-75K, and 1K from 75-300 K.

Stable detectors, internal blackbody calibration target, frequent looks into space

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Level 1 Req.

Instrument Level 2:



Comment

Level 2 Req.


M50-DIVINER

Subset of DLRE-L2-10

To characterize temperatures over a full lunar diurnal cycle requires measurements distributed over approximately 10 local times of the lunar day. To achieve this coverage within 5° of the poles, Diviner must have a swath width of at least 1km at 50km altitude.

10 pixels in row, each 300 m on ground

M80-DIVINER

DLRE-L2-6 To determine rock abundances, Diviner must be capable of measuring nighttime emitted thermal radiation of surfaces as low as 70K in at least two non-overlapping spectral channels that span a spectral range as wide as possible while maintaining temperature resolution of 1K.

25-50μm and 50-100μm micron high-sensitivity thermal bands

M90-DIVINER

DLRE-L2-7 To produce polar illumination maps, Diviner must make simultaneous and spatially coincident broadband solar reflectance and thermal emission measurements.

Two solar and four thermal co-aligned arrays

M90-DIVINER

DLRE-L2-8 To produce polar illumination maps, Diviner must measure broadband solar reflectance and thermal emission measurements with roughly equal detection thresholds (~24K for thermal emission, and 3x10-5 times the broadband solar reflection for a normally illuminated, perfectly diffusing unit albedo surface at 1 AU).

One high-sensitivity solar band and one high-sensitivity 100-200μm thermal band

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Level 1 Req.

Instrument Level 2:



Comment

Level 2 Req.


M90-DIVINER

DLRE-L2-9 To produce polar illumination maps, Diviner must make solar reflectance measurement accurate to the larger of 3% of local reflectance, or 0.1% of the maximum solar reflectance from the moon.

Solar calibration target

M90-DIVINER

DLRE-L2-5 To produce polar illumination maps, Diviner must measure surface brightness temperature with an accuracy of 5K from 40-55K, 2.5K from 55-75K, and 1K from 75-300 K.


M100-DIVINER

DLRE-L2-10

To measure thermal inertia and lambert albedo over a majority of the lunar surface, Diviner must have a swath width of at least 3km at 50km altitude.

10 pixels in row, each 300 m on ground

M100-DIVINER

Subset of DLRE-L2-5

To measure thermal inertia, which requires night time surface temperature measurements, Diviner must measure surface brightness temperature with an accuracy 1K from 75-200 K.


08 - 10


Level 1 Req.

Instrument Level 2:



Comment

Level 2 Req.


M100 DLRE-L2-11

To differentiate different silicate classes and locate ilmenite below 80° latitude, Diviner must have at least two spectral channels between 7-13 m and one channel near 15 m with spectral bandwidths ≤1.2 mm.

Three mineralogy spectral bands in 7-16 μm range

M100 DLRE-L2-12

To differentiate different silicate classes below 80° latitude, Diviner must have signal-to-noise ratios of at least 100 in the 7-13 mm spectral bands for temperatures greater than 250 K.

High sensitivity in mineralogy bands

08 - 11

Level 2 Req. Level 3: DLRE Functional Requirements JPL-D-32375

Level 3 Req. # Laser Design Requirements

DLRE-L2-1

(≤6mrad IFOV) 43The nominal IFOV of each detector shall be 3.58 mrad by 6.15 mrad, corresponding to 178 m cross track and 308 m in track at an altitude of 50 km.

44 IFOV response: 85% within nominal IFOV, 98% within 3x nominal IFOV

DLRE-L2-2

(≤180 ms integration time)

294The focal plane interface electronics shall digitally integrate the 14-bit samples for each ASIC channel and deliver 16-bit integrated samples to software at nominally 0.128 second intervals.

DLRE-L2-3 (SNR≥1 at 24K)

33 Channel B3: 100-200μm.

84 Noise-Equivalent In-Band Spectral Radiance (W/cm2stm) for channel B3 ≤5.4e-9.

DLRE-L2-4 (multiple bands ≥15-150μm)

33Channel A6: 12.5-25 μm; Channel B1: 25-50 μm;

Channel B2: 50-100 μm; Channel B3: 100-200 μm

Instrument Subsystem Level Requirements (1)

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DLRE-L2-5 (Accurate thermal measurements)

68,69Radiance in thermal channels calibrated to better than 0.5% of 300K blackbody radiance. Precision to better than 0.1% of 300K blackbody radiance.

229 Blackbody calibration target mounted to instrument base.

134Elevation drive shall have range of 270° to allow looks into space and at blackbody calibration target.

DLRE-L2-6 (Two non-overlapping bands with T≤1K at 70K)

33 Channel B1: 25-50 μm; Channel B2: 50-100 μm

84Noise-Equivalent In-Band Spectral Radiance (W/cm2stm) for channel B1 ≤2.2e-8.

Noise-Equivalent In-Band Spectral Radiance (W/cm2stm) for channel B2 ≤1.1e-8.


08 - 13



DLRE-L2-7 (simultaneous and coincident

39 Six parallel and aligned linear arrays – two solar and four thermal.

solar and thermal measurements)

50,51 Telescopes A and B aligned to better than 0.6mrad.

DLRE-L2-8

(Roughly equal solar and

33Channel A1: 0.3-3 μm

Channel B3: 100-200μm.

thermal detection thresholds)

84Noise-Equivalent In-Band Spectral Radiance (W/cm2stm) for channel A1 ≤2.0e-7. Noise-Equivalent In-Band Spectral Radiance (W/cm2stm) for channel B3 ≤5.4e-9.

DLRE-L2-9 (accurate solar measurements)

74 Solar measurements calibrated to 3% accuracy and 0.1% precision.

238 Solar calibration target mounted to instrument base.

114,134 Azimuth and elevation drives allow looks into space and at solar cal target


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DLRE-L2-10 (swath width 3km)

259,267Focal plane A shall have 6 linear arrays each with 21 detectors.

Focal plane B shall have 3 linear arrays each with 21 detectors.

43IFOV of each detector shall be 3.58 mrad by 6.15 mrad, corresponding to 178 m cross track and 308 m in track from the LRO orbiter at an altitude of 50 km.

DLRE-L2-11 (Three spectral channels in 7-16μm range)

33 Channel A3: X-XX μm; Channel A4: Y-YY μm

DLRE-L2-12 (SNR≥100 above 250K in mineralogy channels)

84Noise-Equivalent In-Band Spectral Radiance (W/cm2stm) for channel A3 ≤X Noise-Equivalent In-Band Spectral Radiance (W/cm2stm) for channel A4 ≤Y


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Data Product Traceability

Level Diviner Data Products Inputs

0 Depacketized time-sequenced raw science and houskeeping data

Raw science and housekeeping

1a Calibrated radiances and housekeeping data Level 0

1b Calibrated radiances and housekeeping data merged with project supplied geometry and timing

Level 1a plus project-supplied NAIF and SPICE

2 Gridded (lat,lon,local time) global surface temperatures

Level 1b

2* Queryable web version of Level 2, including annual min/max/average temps

Level 2

3 Gridded global fields: Lambert albedo, fine-component thermal inertia, rock abundance

Level 2 + Gridded global topography + 3D illumination model + 1D thermal model

3* Queryable web version of Level 3 Level 3

4 Polar Resource Products: Localized maps of derived surface and subsurface temperatures, thermal inertia, near-IR maps

Levels 1-3 + 3D illumination and scattering model

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DLRE Constraints on LRO

Title Requirement Rationale

Sun Damage Diviner shall never look at the Sun, even for a few milliseconds during nominal or emergency S/C operations

Focal plane detectors will be destroyed

Calibration 1 The spacecraft shall provide cross-track space views for Diviner 90° from nadir in the anti-sun hemisphere

Space and internal BB target calibration views required 10 times per orbit

Calibration 2 Diviner shall be mounted to the IM to ensure the solar calibration target can be fully illuminated by the sun each orbitl.

Solar calibration required once per orbit, accomplished by azimuth and elevation gimbals.

Pointing Accuracy Pointing requirements (pitch, roll, and yaw)

Control 6.0 mrad, Knowledge 3.0 mrad, Stability 1.5 mrad in 0.128 seconds

Needed for image registration and reconstruction, and to reduce FOV smearing

Ephemerides Reconstruction knowledge in lunar centered coordinates: Tangential <150 m, Radial < 300 m

Needed for image registration and reconstruction

08 - 17

Instrument Schematic Diagram

Azimuth Joint

Elevation Joint

Yoke

Cal. Target

Spacer, azimuth

Optical Bench Assy.

Left/Right Side Plate, OB

Solar Target

Close-out plates

Azimuth Joint

Elevation Joint

Yoke

Cal. Target

Spacer, azimuth

Optical Bench Assy.

Left/Right Side Plate, OB

Solar Target

Close-out plates

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Optical System Layout

Telescope A Telescope B

PrimaryTertiary

SecondaryFocal PlaneArrays & Filters

Baffles

08 - 19

Electronics Block Diagram

FP A6x210.3-25um

FP B3x2125-200um

RO

IC

focalplaneinter-face

RAM32KB

processor69RH051

stepper driversposition sensors

FPGA

house-keeping

EMI filterDC/DC converters

Power

Surv Heat

422inter-face

6

Timetick

2 +28V

TTL

ElevationStepper

heatercontrol

BB heater

AzimuthStepper

PROM32KB

12

2

2

S/C InterfaceCommand,Telemetry

linear regulators

3 c/d/e

3 c/d/e

OBA heater

HK sensors

sensorsheaters

PAS

2 +28V

3 ctrl

3 power

4

4

1 analog

1 analog

3 ctrl

3 power

1 analog

ANA board

CTL board

PWR2 board

PWR1 board

RO

ICR

OIC

RT54SX32S-CQ256E

422inter-face

External Electronics Box

RAM32KB

processor69RH051

PROM32KB

1553interface

08 - 20

Development Flow

Electronics / YokeAssembly

Azimuth Drive / YokeAssembly

Elevation Drive / YokeAssembly

FPA / FiltersAssemble & Align

Telescopes / OpticsAssemble & Align

Optics Bench /Electronics Assembly

Telescopes / OpticsBench Install & Align

Radiometer / Yoke Assembly

Functional Testing

08 - 21

Instrument Verification

Characteristic Pre-Flight Verification Method

(Instrument Level Unless Noted)

In-Flight Verification Method

IFOV Scanning slit source across field of view

None

Spectral Bandpasses Scan wavelength with monochrometer None

Radiometric Accuracy and Signal-to-Noise

Ratio – Thermal Bands

Cold and hot blackbody sources Looks into space and at internal blackbody calibration target

Radiometric Accuracy and Signal-to-Noise Ratio – Solar Bands

Calibrated lamp source Looks into space and at solar calibration target

Alignment Between Telescopes A and B

Scanning slit source across field of view

Scanning across horizon

Alignment with Other Instruments

Scanning slit source across field of view (orbiter level)

Scanning across horizon

(both axes)

Test plans, procedures and results are archived in the JPL Project Data Management System or DLRE Docushare Library. Hardcopies of as-run test procedures and test results will be contained in the end-item data package. All documentation is controlled per the DLRE Configuration Management Plan.

08 - 22

Instrument Current Status

• Major mechanical, optical, and electronic systems are build-to-print

• Solar and thermal spectral pass bands selected

• Architecture for external interface box complete

• Mineralogy spectral pass band optimization study under way

• Study underway to select optimal modifications to mitigate warmer thermal environment (thicker blankets verses higher reflectivity on outer blankets verses high reflectivity shield)

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Schedule

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Summary

• Diviner is a heritage instrument – it differs from Mars Climate Sounder in:– Spectral bands (different filters)– Shorter integration time– Different interface to spacecraft– Warmer thermal environment

• Diviner requirements are well understood and documented in:– DLRE Instrument Performance Requirements Document– DLRE Data Product Specification Document – DLRE Function Requirements Document

• DLRE constraints LRO have been flowed down and are documented in the LRO MRD• Design status:

– Contract for filter design and fabrication in negotiation– Design for hardware/software interface to spacecraft underway– Trade study underway to reduce thermal load in lunar environment

LRO System Requirements Review Diviner Lunar Radiometer Experiment Requirements

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