Transcript Slide 1

LRO System Requirements Review
Lunar Exploration Neutron Detector (LEND)
Requirements & Implementation
Igor Mitrofanov
Principle Investigator
Russian Institute for Space Research
10 - 1
Institutions of LEND Instrument Team
Institute for Space Research, Russia
Sternberg Institute of Astronomy,
Russia
Joint Institute of Nuclear Research,
Russia
University of Maryland, USA
NASA/Goddard Space Flight Center,
USA
University of Arizona, USA
Catholic University of America, USA
Computer Science Corporation, USA
10 - 2
LEND Science Overview and Theory of Operations
STN 1
STN 2
SETN
STN 3
LEND sensors of STN1-3 and SETN
detect thermal neutrons and epithermal
neutrons to characterize Lunar
Radiation Environment.
STN1 and STN3 operates as Doppler
filter for thermal neutrons from front
side and back side of LEND
LRO
velocity
vector
SETN and STN2 have open fields of view
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LEND Science Overview and Theory of Operations
LEND sensor SHEN detects high
energy neutrons at 16 energy channels
from 300 keV to >15 MeV to
characterize Lunar Radiation
Environment
SHEN
SHEN has narrow field of view about
20-30
10 - 4
LEND Science Overview and Theory of Operations
LEND collimated sensors CSETN1-4 detect epithermal neutrons
with high angular resolution to characterize spatial variations of
Lunar Neutron Albedo, which depend on content of hydrogen in 12 m of the regolith
epithermal neutrons
CSHEN 2
CSHEN 1
H
CSHEN 3
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LEND Science Overview and Theory of Operations
LEND collimated sensors CSETN1-4 and SHEN detect
epithermal neutrons and high energy neutrons with high angular
resolution to test water ice deposit on the surface
water ice
epithermal neutrons
high energy neutrons
CSHEN 2
CSHEN 1
CSHEN 3
SHEN
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LEND Heritage
Plastic Anti-coincidence for Sensor of HEN
Collimator of neutrons
Larger counters of neutrons
HEND/Odyssey is LEND prototype with few design changes
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LEND Heritage
LEND electronics has only one design change in respect to HEND
Design Change
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LEND Documentation
Project:
LRO Program Requirements Document;
LRO Mission Requirements Document;
Technical Resource Allocations;
ESMD-RLEP-0010
431-RQMT-00004 LRO
431-RQMT-000112
Instrument:
Instrument Payload Assurance Implementation Plan
Instrument to Spacecraft Interface Control Documents
Mechanical
Thermal
Electrical
Data
Instrument Requirements Document
LEND PAIP 01
431-ICD-000088
431-ICD-000119
431-ICD-000097
431-ICD-000107
LEND IRD 01
Contract documents with Russian Federal Space Agency
Draft of LEND Implementation Agreement between NASA and FSA
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LEND Mission Level Requirements
LRO
Req.
ESMDRLEP-0010
Level 1: Requirements
Instrument
LRO Mission
Requirement
Required Data Products (LEND Level 3 and 4)
RLEP-LROM110
LEND
The LRO shall map hydrogen
on the Moon's surface with 5
km spatial resolution at the
poles for concentrations equal
or greater than 100 ppm with
3-sigma confidence.
The LRO shall obtain high
spatial resolution hydrogen
mapping of the Moon's surface
to a 20% accuracy and 5 km
resolution at the poles.
LEND Surface Composition Data Product (LEND SCDP):
LEND SCDP#1: Map of hydrogen composition with pixels of 2 km for northern area
>60N
LEND SCDP#2: Map of hydrogen composition with pixels of 2 km for southern area
>60S
LEND SCDP#3: Map of hydrogen composition with pixels of 5-10 km for equatorial
belt between >60N and >60S
Determine hydrogen content of subsurface at polar regions with spatial resolution from
Half-Width Half-Maximum (HWHM)=5km and with variation sensitivity from 100
parts per million (ppm)
RLEP-LROM070
LEND
The LRO shall identify putative
deposits of appreciable surface
or near surface water ice in the
Moon’s polar cold traps at km’s
100m scale spatial resolution
LEND Surface Composition Data Product (LEND SCDP):
LEND SCDP#4: Map of water ice deposits with pixels of 2 km for northern area
>60N
LEND SCDP#5: Map of water ice deposits with pixels of 2 km for southern area
>60S
Develop maps of water ice column density on polar regions of the Moon with spatial
resolution from 5-20km.
RLEP-LROM010
LEND
The LRO shall characterize the
deep space radiation
environment in lunar orbit,
including neutron albedo.
LEND Radiation Data Products (LEND RDP):
LEND RDP #1: Maps of thermal neutrons below 0.4 eV, epithermal neutrons at two
energy ranges (0.4 eV – 3.0 keV) and (3 – 300 ) keV and maps of high energy neutrons
at 16 energy channels from 300 keV up to 15 MeV for 52 time periods of 7 days
LEND RDP #2: Time profiles of thermal neutrons below 0.4 eV, epithermal
neutrons at two energy ranges (0.4 eV – 3.0 keV) and (3 – 300 ) keV and maps of high
energy neutrons at 16 energy channels from 300 keV up to 15 MeV for each detected
SPE
LEND RDP #3 (optional, provided LEND-LRO R3# accepted): Angular distribution
of epithermal and high energy neutron components of lunar space radiation 10 - 10
environment from Nadir to Horizon at 15 steps
Radiation Data Product for global distribution of neutrons at Moon’s orbit with spatial
LEND Instrument System Level Requirements
Instrument Level 2 Requirements
(LEND IRD 01)
Level 1 Req.
Requirement
no.
Concept/Realizability
/Comment
LEND Instrument Measurement Requirement
M 110-LEND
LEND IMR 1
Measure global distribution of hydrogen in lunar
subsurface; at polar regions provide spatial resolution
from 5 km (Half-Width Half-Maximum, HWHM) and
variation sensitivity with confident detection limit of 100
weight parts per million (ppm)
Determine hydrogen content of subsurface at polar
regions with spatial resolution from Half-Width HalfMaximum (HWHM)=5km and with variation sensitivity
from 100 parts per million (ppm)
LEND has imaging capability for lunar flux of epithermal
neutrons (collimated sensors CSETN 1-4), which
variations are the most pronounced signature of hydrogen
content in the subsurface layer of 1-2 meters
M 070-LEND
LEND IMR 2
Measure or estimate upper limit of water ice column
density on polar regions of the Moon with spatial
resolution of 5-20 km
Develop maps of water ice column density on polar
regions of the Moon with spatial resolution from 5-20km.
LEND has imaging capability for lunar flux of epithermal
neutrons (collimated sensors CSETN 1-4) and high energy
neutrons (sensor SHEN): relationship of variations of these
neutrons provides the signature of water ice deposits on
polar regions of Mars
M 10-LEND
LEND IMR 3
Measure global distribution of neutrons at Moon’s orbit
with spatial resolution of 50 km at different energy
ranges from thermal energy to >15 MeV separately for
periods of quiet Sun and for periods of Solar Particle
Events
Radiation Data Product for global distribution of
neutrons at Moon’s orbit with spatial resolution of 50 km
at different energy ranges from thermal energy up to >15
MeV separately for periods of quiet Sun and for periods
of Solar Particle Events.
LEND has the necessary-and-sufficient set of sensors for
entire energy range from thermal energy domain to 15
MeV and higher, which allow to build up comprehensive
physical model of neutron component of radiation
environment both for quiet Sun period and for episodes of
SPE
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LEND Instrument System Level Requirements
Level 2
Req.
Instrument Level 2a Requirements
(LEND IRD 01)
Requirement
no.
Concept/Realizability/Comment
LEND Instrument Functional
Requirement
LEND
IMR 1
LEND FR 1
Measure epithermal neutrons by 4 similar
collimated sensors with counting rate about 0.3
counts/sec within narrow FOV, which allows to
detect polar spot with 100 ppm of hydrogen and
radius of 5 km at 3-sigma confidence
Narrow FOV of CSETN 1-4 is produced by passive collimator
module from 10BC4 and polyethylene; realizability to be proved
by Monte Carlo numerical modeling and physical tests of
laboratory prototype unit
LEND
IMR 2
LEND FR 2
Measure high energy neutrons by narrow field
sensor at 16 energy channels from 300 keV to >
15 MeV
SHEN has plastic anti-coincidence shield to reject counts from
charge particles; narrow field of view is produced by center hole
of collimator module for counters CSETN 1-4 (*.
Joint analysis of data from CSETN 1-4 (FR 1) and from
scintillator SHEN (FR 2) allows to detect layering structure of
water ice deposits
LEND
IMR 3
LEND FR 2
See above
See above (*
LEND FR 3
Measure thermal neutrons by two Doppler-filter
sensors
Signal of Doppler filter, which is subtraction of counts of front
side counter STN 1 from counts of back side counter STN 3,
exclude local background of spacecraft
LEND FR 4
Measure thermal neutrons by open-field sensor
LEND FR 5
Measure epithermal neutrons by open field sensor
Counter SETN has Cd enclosure and its counts rate characterizes
total flux of epithermal neutrons at the orbit. Difference of
counts from STN 2 and SETN characterizes total flux of thermal
neutrons at the orbit
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LEND Instrument System Level Requirements
Instrument Level 3 Requirements
(LEND IRD 01)
Level 2
Req.
Requirement
no.
Concept/Realizability
/Comment
LEND Instrument Design
Requirement
LEND FR
1
L3-DR 01
Measure epithermal neutrons with
counting rate about 0.3 counts/sec
inside FOV of about 5.6 at each
collimated counter CSETN 1-4
Monte Carlo simulations show that optimal design of
collimator together with appropriate selection of 3He
counter of neutrons allow to obtain necessary counting
rate for SETN 1-4 sensors within allocated mass (see
backup page TBD). Selected prototype for counters is
LND 25311.
LEND FR
3, 4 and 5
L3-DR 02
Measure thermal and epithermal
neutrons in CTN 1-3 and SETN with
counting rate about 10 cts/sec
Monte Carlo simulation of lunar neutron albedo allows to
select necessary type of 3He counters for STN 1-3 and
SETN for getting this counting rate. Selected prototype for
counters is LND 25311.
LEND FR
1, 3-5
L3-DR 03
Provide signal processing from counters
CSETN 1-4, STN 1-3 and SETN
Each signal will be digitized in 16 channels of amplitude
and loaded into corresponding place of LEND telemetry
frame (HEND heritage)
L3-DR 04
Provide changeable HV about 2 kV for
counters CSETN 1-4, STN 1-3 and
SETN
Turn on/off and Levels of HV may be operated
individually for each counter (HEND heritage)
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LEND Instrument System Level Requirements
Instrument Level 3 Requirements
(LEND IRD 01)
Level 2
Req.
Requirement
no. or para.
LEND FR 2
Concept/Realizability/Comment
LEND Instrument Design
Requirement
L3-DR 05
Provide changeable HV about 2 kV for
PMT of SHEN
HEND heritage
L3-DR 06
Distinguish SHEN counts from neutrons
and counts from gamma-rays
Pulse-shape analyzer will be used for signal from
PMT, which allows to separate counts from proton
(detection of neutron) from electron (detection of
gamma-ray) with probability of mistake less than
10-3 (HEND heritage)
L3-DR 07
Measure high energy neutrons at the energy
range (300 keV, >15 MeV) with counting
rate about 0.3 cts/sec
Monte Carlo simulation of lunar neutron albedo
allows to select size of sthylbene scintillation
sensor SETN for getting this counting rate within
narrow FOV (HEND heritage).
L3-DR 08
Provide 2 signals (neutrons and gammas)
processing in 16 energy channels
Each signal will be digitized in 16 channels of
amplitude and loaded into corresponding place of
LEND telemetry frame (HEND heritage)
L3-DR 09
Provide anti-coincidence shielding for
SHEN for exclusion detection of external
charge particles
Sthylbene crystal will be surrounded by plastic
scintillator with photo-diodes read-out, which
generates veto anti-coincidence signal for each
crossing charge particle (HEND heritage)
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LEND Data Product Traceability
LEND
Data
Description
Required Input
Unprocessed LEND rough telemetry data with science measurements, instrument
housekeeping information. Spacecraft LEND-related data
Spacecraft LEND-related data
LEND Level 0
LEND Level 1
LEND sensors counting rate, LEND physical calibration data, spacecraft trajectory and
pointing data, LEND sensors counting rate from background, solar activity data
Spacecraft timing, trajectory and
pointing data, spacecraft data for
fuel consumption, CRaTER level
TBD data, GOES solar data
LEND level 2
LEND neutron mapping data (flux of neutrons per pixel) and/or time profiles with integration
time and pixelization individually selected for each sensor
LOLA level TBD data, Diviner
level TBD data
LEND Surface Composition Data Product (LEND SCDP):
LEND SCDP#1: Map of hydrogen composition with pixels of 2 km for northern area >60N
LEND SCDP#2: Map of hydrogen composition with pixels of 2 km for southern area >60S
LEND SCDP#3: Map of hydrogen composition with pixels of 5-10 km for equatorial belt
between 60N and 60S
LEND SCDP #4: Map of water ice deposits with pixels of 2 km at northern area > 80N
LEND SCDP #5: Map of water ice deposits with pixels of 2 km at southern area > 80S
LOLA level TBD data, Diviner
level TBD data, LAMP level TBD
data
LEND Radiation Data Products (LEND RDP):
LEND RDP #1: Maps of thermal neutrons below 0.4 eV, epithermal neutrons at two energy
ranges (0.4 eV – 3.0 keV) and (3 – 300 ) keV and maps of high energy neutrons at 16 energy
channels from 300 keV up to 15 MeV for 52 time periods of 7 days
LEND RDP #2: Time profiles of thermal neutrons below 0.4 eV, epithermal neutrons at two
energy ranges (0.4 eV – 3.0 keV) and (3 – 300 ) keV and maps of high energy neutrons at 16
energy channels from 300 keV up to 15 MeV for each detected SPE
CRaTER level TBD data
LEND level 3
LEND level 4
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LRO Requirements Driven by LEND
RLEP-LRO Requirement
LEND measurement requirements
LRO requirement driven by
LEND
RLEP-LRO-M110: The LRO shall map
hydrogen on the Moon's surface with 5
km spatial resolution at the poles for
concentrations equal or greater than 100
ppm with 3-sigma confidence.
LEND IMR 1: Measure global distribution
of hydrogen in lunar subsurface; at polar
regions provide spatial resolution from 5
km (Half-Width Half-Maximum, HWHM)
and variation sensitivity with confident
detection limit of 100 weight parts per
million (ppm)
LEND-LRO R#1: For neutron
mapping measurements provide
continuously pointing of LEND
collimated detectors into nadir direction
RLEP-LRO-M70: The LRO shall
identify putative deposits of appreciable
surface or near surface water ice in the
Moon’s polar cold traps at km’s scale
spatial resolution
LEND IMR 2: Measure or estimate upper
limit of water ice column density on polar
regions of the Moon with spatial resolution
of 5-20 km
The same LEND-LRO R#1 (see above)
RLEP-LRO-M10: The LRO shall
characterize the deep space radiation
environment in lunar orbit, including
neutron albedo.
LEND IMR 2: Measure global distribution
of neutrons at Moon’s orbit with spatial
resolution of 50 km at different energy
ranges from thermal energy to >15 MeV
separately for periods of quiet Sun and for
periods of Solar Particle Events
The same LEND-LRO R#1 (see above)
LEND-LRO R#2: Operate LEND
constantly from cruise orbit insertion
during the entire mission
LEND-LRO R#3: Provide opportunity
for sessions of special measurements
with different angles of collimated
detectors from Nadir to Horizon
(suggested, as optional. in addition to
baseline mission scenario, provides
additional LEND Data Product LEND
RDP #3)
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LEND Constraints on LRO
Title
Requirement
Rationale
Traceability
Require 15° to 20° off-point down-track or
cross-track for stereo imaging three times a
day.
Stereo image of same ground spot under similar
lighting conditions. Issue with LOLA’s coverage
spec regarding time off-nadir (less than 3% of
total time). Working issue. Thermally OK for 20°
off-point for 20 minutes total.
Stereogrammetric and
photometric stereo data
set generation (RLEPLRO-M40)
Mosaickin
g
Off-nadir pointing to get contiguous coverage
over wider ground swath three times a day. Offpointing requests would range from 2° to 20°.
Allow acquisition of contiguous NAC swaths to
cover entire landing site error ellipses and
region of surface operations.
Landing Site safety
(RLEP-LRO-M80)
Data Link
LROC shall receive all commanding and
distribute all telemetry over the SpaceWire high
speed bus.
Simplify spacecraft to instrument interface at
GSFC request
Science requirements for
high resolution, high
temporal resolution, etc.
data require high
bandwidth download
(RLEP-LRO-M40, M80,
M90, M100)
Data Rate
LROC shall write 8 bit data to the Transmit
FIFO at a clock rate for the SpaceWire STROBE
signal of 40MHz without invocation of Transmit
FIFO flow control.
Required to deliver NAC data from SCS to use
up downlink allocation, maximize science return,
avoid data loss (heritage design does not use
flow control).
See Data ICD
(RLEP-LRO-M40, M80,
M90, M100)
Mass
Allocation
16.5 kg with margin
Includes 20% contingency over CBE.
Based on proposal
estimates
NAC: 2.86° per NAC, total 5.7° crosstrack.
WAC: 90° crosstrack.
Required for swath width
(RLEP-LRO-M40, M80,
M90, M100)
Stereo
Imaging
Science
FOV
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LEND Block Diagram
LEND
Sensor
SETN
Actel FPGA (RTAX series)
SETN/FRE
LVP
Sensor
STN1
HV1
STN1/FRE
Sensor
STN2
HV2
Sensor
STN3
HV3
STN3/FRE
Sensor
CSETN1
HV4
IO Drivers
CSETN1/FRE
Sensor
CSETN2
Redundant MIL-STD-1553B
HV5
CSETN2/FRE
Sensor
CSETN3
LRO Spacecraft
Heaters
Control
STN2/FRE
IC
HV6
CSETN3/FRE
Sensor
CSETN4
HV7
ADC
CSETN4/FRE
HV8
HV9
4
Sensor
SC/N
Stilbene
SC/N/
FRE&S
SC/N/SA
Neutron
Energy
Code
G/N
N/G
TCS
ACS
Sensor
SC/AC
Block
SC/AC/
FRE
LEND
Instrument
Main
Structure
HV1
HV2
HV3
HV4
HV5
HV6
HV7
HV8
HV9
High
Voltages
Values
RAM
Clock
Generator
HV/
STN/
CSETN
10 - 18
LRO Integration
Integration
tests
onboard
LRO
LRO Env. Req.
Functional Req. Design Req.
Stages of LEND development
LEND Development Flow
Qualification
tests for LRO
environment
requirements
Acceptance
tests for LRO
environment
requirements
Laboratory tests
with neutron
sources, verification
tests for LRO
environment
requirements
Laboratory tests
with neutron
sources
and numerical
simulations
LEND units
LEND LU
LEND EU
LEND QU
LEND FU01
LEND FU02
10 - 19
List of Procedures and Verification Tests
•
•
•
•
•
•
•
Reliability Analyses (RA)
• Failure Modes, Effects and Criticality Analysis (FMECA)
• Electronic Parts Stress Analysis (PSA)
• Thermal Stress Analysis
• Structural Stress Analysis
• Single Event Effects Analysis (SEE)
Screening of all electrical, electronic and electromechanical parts (SEEE)
Preparation of Confirmation Lists of Material and Components (CLMC)
Environmental Requirements (ER)
• Radiation durability analysis
• Random vibration and shock tests
• Thermal vacuum test
• Electromagnetic compatibility tests
• Thermal cycling life test
Contamination Control (CC)
Preparation of Problem/Failure Anomaly Report (PFAR)
Accumulation of Hardware Operating Hours prior delivery (HO)
10 - 20
LEND Current Status
•Trade studies which have been closed
•
Concept of LEND configuration
•
Electrical interface design
•
Selection of sensors and major electronic components
•
Concept of thermal design
•
Concept of mechanical design
•
Manufacturing documentation for LEND LU
•
Cooperation in Russia for LEND manufacturing
•Outgoing trade studies
•
Optimization of collimator unit of SETN 1-4 for the best sensitivity for 5 km radius spot at pole with
enhancement of H
•
Optimization of narrow field of view for detector of high energy neutrons SHEN
•
Thermal model of instrument
•Analysis currently being performed
•
Numerical model of Moon neutron albedo at different energy ranges
•
Estimation of instrument fundamental frequency ( > 75 Hz)
•
Software for data processing of LEND LU
•Hardware currently in development
•
Mechanical elements of LEND LU
•
Collimator units of LEND LU
•
Electronic boards of LEND LU
7. What is the status of the agreements?
10 - 21
LEND Development Milestones
Name
Work
LU
Development
2004
2005
2006
2007
2008
Testing&verification
EIS
Development
Testing&verification
Delivery
EU
Development
Testing&verification
Delivery
QU
Development
Testing&verification
Calibrations
FU01
Development
Testing&verification
Calibrations
Delivery
FU02
Development
Testing&verification
Calibrations
Delivery
10 - 22
Summary
1. LEND is developing in response to RLEP-LRO M010, M070 and M110: corresponding flows
from LRO Mission requirements to LEND Functional Requirements and Design Requirements are
well understood
2. Data Products of LEND are defined, which correspond to RLEP-LRO M010, M070 and M110
3. LEND development process ensures that LEND Flight Unit will provide defined Data Products
4. LEND accommodation on LRO ensures that LEND will be able to provide defined Data
Products
5. There is only one additional requirement to LRO driven by LEND (measurements at different
angles from Nadir to Horizon) which is not presented in the mission baseline. This operation
provides additional data products on Lunar Radiation Environment (angular distribution of
neutron component)
6. LEND team is ready to move to the preliminary design stage
7. What is the status of the agreements?
10 - 23