Transcript Slide 1

Cosmic dust Reflectron for
Isotopic Analysis (CRIA)
Conceptual Design Review
Laura Brower: Project Manager
Drew Turner: Systems Engineer
Loren Chang
Dongwon Lee
Marcin Pilinski
Mostafa Salehi
Weichao Tu
Presentation Overview
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Introduction to Problem – Loren Chang
Previous Dust Analyzers – Loren Chang
LAMA Overview – Marcin Pilinski
Introduction to CRIA – Weichao Tu
Requirements – Drew Turner
Verification – Marcin Pilinski
Risk – Laura Brower
Current Analyses and Trades – Mostafa Salehi
Schedule – Dongwon Lee
Space is Dusty!
• Space is filled with particles ranging
in size from molecular to roughly
1/10th of a millimeter.
• Dust absorbs EM radiation and
reemits in the IR band.
• Dust can have different properties
and concentrations, ranging from
diffuse interstellar medium dust to
dense clouds, and planetary rings.
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Loren Chang
Interstellar dust is believed to be produced by
older stars and supernovae, which expel large
amounts of oxygen, silicon, carbon, and other
metals from their outer layers.
Clouds of dust and gas cool and
contract to form the basic building
blocks for new stars and planetary
systems.
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Comets, asteroids, and collisions in the new
planetary system produce interplanetary dust.
Heritage
• Past instruments have focused primarily on
understanding the flux and chemical composition
of cosmic dust.
• Missions have focused on in-situ measurement and
sample return.
Aerogel Collector
CIDA
CDA
Loren Chang
SDC
Student Dust Counter
(New Horizons)
• Polyvinylidene fluoride
(PVDF) film sensors.
• In-situ measurement of
dust flux, mass, and
relative velocity.
• Cannot resolve smaller
particles (< 10-12 g) nor
measure elemental
composition.
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lasp.colorado.edu/sdc
Cosmic Dust Analyzer
(Galileo, Ulysses, Cassini)
• Incoming dust particles
ionized, then accelerated
through electric field to
detector.
• Time of Flight (TOF) used
to infer elemental masses
of constituents.
• Parabolic target is difficult
to manufacture precisely.
Low mass resolution (2050 m/Δm)
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R. Srama et al., The Cosmic Dust Analyzer (Special
Issue Cassini, Space Sci. Rev., 114, 1-4, 2004, 465518)
Target
Stardust
• Interstellar and
interplanetary dust
particles trapped in
aerogel.
• Direct sample return for
analysis of elemental
composition on Earth.
• Requires highly
specialized mission.
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stardust.jpl.nasa.gov
Cometary and Interstellar Dust Analyzer
(Stardust)
• Uses impact ionization
principle similar to CDA,
electric field in reflectron is
parabolic, eliminating the need
for a parabolic target.
Improved mass resolution over
CDA (250 m/Δm)
• Small target area compared to
previous instruments. Roughly
1/20th target area of CDA.
J. Kissel et al., The Cometary and Intersteller Dust
Analyzer (Science., 304, 1-4, 2004, 1774-1776)
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Loren Chang
Large Area Mass Analyzer
LAMA Concept: Sub-systems
IONIZER
Target
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Marcin Pilinski
LAMA Concept: Sub-systems
ANALYZER (Ion Optics)
Annular Grid Electrodes
Ring Electrodes
Grounded Grid
Target
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LAMA Concept: Sub-systems
DETECTOR
Detector
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LAMA Concept: Operation
incoming dust particle
Example Dust Composition
Key
Species-2
Species-3
Target
Example Spectrum
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Increasing mass
Species-1
LAMA Concept: Operation
dust passing through annular electrodes
dust passing through grounded grid
Data collection from detector started
Example Spectrum
t0
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LAMA Concept: Operation
negative ions and electrons accelerated to target
target material also ionizes
dust impacts target and ionizes (trigger- t0)
Example Spectrum
t0
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LAMA Concept: Operation
positive ions accelerated towards grounded grid (trigger- t1)
Ions of Species-1, Species-2, Species3, and Target Material
Example Spectrum
t0
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t1
LAMA Concept: Operation
positive focused towards detector
Example Spectrum
t0
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t1
LAMA Concept: Operation
positive ions arrive at detector
Ions of the same
species arrive at the
detector at the same
time with some spread
Species-1 arrives at detector
Example Spectrum
t0
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t1
t2
LAMA Concept: Operation
positive ions arrive at detector
Species-2 arrives at detector
Example Spectrum
t0
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t1
t2
t3
LAMA Concept: Operation
positive ions arrive at detector
Species-3 arrives at detector
Example Spectrum
t0
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t1
t2
t3 t4
LAMA Concept: Operation
positive ions arrive at detector
Ionized Target Material
Target material has characteristic peak
Example Spectrum
t0
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t1
t2
t3 t4 t5
LAMA is promising, but…
• Several tasks have yet to be completed:
• Dust triggering system not yet implemented.
• No decontamination system.
• System has not yet been designed for or tested in the
space environment.
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Marcin Pilinski
Cosmic dust
Reflectron for
Isotopic
Analysis
Hi, I’m
LLAMA
Hi, I’m CRIA.
Am I Cute?
(a cria is a baby llama)
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Weichao Tu
CRIA Project Motivation
• LAMA Development
– To scale down the LAMA instrument to a size
better suited for inclusion aboard missions of
opportunity. Technology Readiness Level (TRL) of
LAMA can be further improved from level 4 to level
5
• Mission opportunity
– A universal in-situ instrument design is needed for
future mission that can incorporate high
performance and large sensitivity and can be
adapted to various missions.
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Weichao Tu
CRIA Project Goals
• Mission Goal
– Design an instrument capable of performing in-situ measurements of
the elementary and isotopic composition of space-borne dust particles
• Science Goal
– Detect dust particles and determine their mass composition and isotopic
ratios
• Engineering Goals
– Design an instrument based on the LAMA concept that achieves the
following: reductions in size, mass, and power in order to be compatible
with possible missions of opportunity
– Achieve a Technology Readiness Level (TRL) of five or higher for the
instrument
– To investigate the limits of scalability of the instrument and determine
the upper and lower limits of sensitivity (size: between 50% and 125%)
in order to provide statistical data and options for a variety of possible
missions
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Weichao Tu
Baseline Design
• Inherited
Heater
DTS
t2
Heater t0
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t1
t-1
from LAMA
concept
•Triggering system
•Scaling LAMA by a factor
of 5/8
•Capable of heating the
Cover
target
area for
decontamination
•Capable of interfacing with
a dust trajectory sensor
(DTS)
•A closed design with a
cover
•MCP detector may be
changed to a large area
detector
Baseline Design ‫װ‬
• Specifications of CRIA and LAMA
Parameter
CRIA
LAMA
Effective Target Area (m2)
>0.045
0.2
Mass Resolution (m/m)
>100 (team goal of 200)
200
Diameter (cm)
40
64
Power Consumption (W)
<10
>10
Instrument Mass (kg)
<10
>10
Weichao Tu
Previous Instrument Comparison
Measurement
Type
Instrument Type
Parameters
Measured
Mass
Resolution
Surface
Area (m2)
In-Situ
Time-of-Flight
Reflectron
Flat
electrode&Target
Flux and
Composition
>100 (team
goal of 200)
0.13
LAMA
In-Situ
Time-of-Flight
Reflectron
Flat
electrode&Target
Flux and
Composition
200
0.32
SDC
In-Situ
PVDF
Flux
-
0.125
Stardust
Sample
return
Aerogel collector
Composition
-
0.1
CDA
In-Situ
Time-of-Flight
Parabolic Target
Composition
50
0.1
CIDA
In-Situ
Time-of-Flight
Reflectron
Composition
250
0.005
Instrument
CRIA
Requirements: Top Level
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1.TR1
4
The instrument shall be derived from the LAMA concept
1.TR2
1
The instrument shall measure the mass composition of
dust particles with a simulated mass resolution of at
least 100 m/Δm [Team goal: 200 m/Δm]. Mass
resolution is derived from the full width of the mass
peak, m/Δm = t/2Δt, where t is time of flight and Δt is
the base peak-width.
1.TR3
3
The instrument shall be capable of mechanically
interfacing with a dust trajectory sensor (DTS)
1.TR4
2
The instrument shall be designed to meet the
requirements of TRL 5
1.TR5
5
The total project cost shall not exceed $25,000.00
1.TR6
6
The instrument shall be constructed and verified by 1
December 2007
1.TR7
7
Complete design documentation shall be delivered by 1
May 2007
Drew Turner
Requirements Flowdown
Level 1:
Analyzer
Top Level Requirements
Ionizer
Level 2: System Requirements
-Functional Reqs
Detector
- Functional Requirements
- Performance Requirements
- Design Constraints
-Performance Reqs
-Design Constraints
Electronics/CDH
- Interface Requirements
Structural/Mechanical
Level 3:
Subsystem Requirements
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Each includes:
Thermal
Drew Turner
-Interface Reqs
Requirements: Levels 2 and 3
• Functional Reqs: Define system functions; answer “what”, “when”,
“where”, and “how many” type questions about the system.
CRIA Example: 2.FR5: The instrument shall be capable of detecting
positive and negative ion species.
• Performance Reqs: Define how well system is to perform its
various tasks; answer “how well”, “how often”, and “within how long”
type questions.
CRIA Example: 2.PR6: The instrument shall be able to record a
mass spectrum from Hydrogen to at least m
= 300 (amu) and be independent of the
triggering method.
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Drew Turner
Requirements: Levels 2 and 3
• Design Constraints: Defines factors that put limits on the system,
such as environment and budget.
CRIA Example: 2.DC1: The instrument shall have a closed design
such that no light can enter the interior
except through the field of view.
• Interface Reqs: Defines system inputs, outputs, and connections to
other parts of the system or to some other, external system.
CRIA Example: 2.IR1: The instrument shall provide a mechanical
interface for the Dust Trajectory Sensor (w/
given mass, dimensions and COG).
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Drew Turner
Requirement Verification Resources
ANALYSIS
Applicable Req
SimIon analysis of time of flight, effective target
area.
TR2, FR2,
PR1, PR6
SolidWorks analysis of mass, structural integrity,
thermal properties
TR3, FR4,
PR4, IR1
TEST
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Bell-Jar
FR3, FR6, DC3
Thermal-Vacuum
PR4
Vibration table
TR4
Marcin Pilinski
System Level Risk Assessment
Sources
Events
Solar UV
Radiation
/ Plasma
Micrometeroid
Prelaunch
Contamination
Material
Outgassing
Mechanical
Malfunction
Detector
damaged
Instrument
charging
Detector
damaged
Contaminated
spectra
Contaminated
spectra
Noise in
spectra
Electronics
malfunction
Target area
damaged
Inaccurate
spectra / no
spectra recorded
Vaporize
contaminants
with heater
Arcing
Mitigation
UV reflective
electrodes
On/Off
detector
mode
Technol.
Risk
Risk
Level
Use rad-hard
electronics
and rad
protect
electronics
Shielding in
annular
electrode
design
Aperture Cover
Use clean room
Medium
Medium
Low
Use low
outgassing mt’ls
UV impact on
detector
unknown
High
•Technology •Instrument •High
•Common
charging not probability
limits
practice
understood of impacts
unknown
Laura Brower
Low
•Materials
known
•Heater temp
range can be
large
High
•No risk
mitigation
Current Analyses and Trades
• Arcing
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Preliminary calculation:
Breakdown electric field as a function of pressure for air
Maximum electric field as a function of gap distance for inner
electrode
- Reduced size increases risk of arcing
-
Unexplored area: The arcing in the plasma
• Material outgassing
- Material selection to low outgassing specification (G-10,
Noryl, ceramic, etc.)
- More details on other material properties (thermal
expansion, tensile strength, density, etc.)
Current Analyses and Trades
•
Thermal power required
-
•
Preliminary calculation on power require to heat target
area to 100 oC is on going
Target design is thermally conductive
Detector protection against UV and
Micrometeoroids
-
We calculated micrometeoroid flux at 1 AU
UV reflection / absorption by coating instrument interior
Determine impact of UV on detector performance
Schedule
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Dongwon Lee
Schedule
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Dongwon Lee
Questions?
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Backup Slides
Previous Instrument Comparison
Instrument
Measurement
Type
Instrument Type
Parameters
Measured
Mass Range
(g)
Target
Area (m2)
SDC
In-Situ
PVDF
Flux
> 10-12
0.125
Stardust
Sample
return
Aerogel collector
Composition
-
0.1
CDA
In-Situ
Time-of-Flight
Parabolic Target
Composition
10-16 - 10-10
0.01
CIDA
In-Situ
Time-of-Flight
Reflectron
Composition
5 x 10-14 - 10-7
0.005
Mass Resolution (m/m)
m
m

m FWHM peak width
• Mass resolution describes the
ability of the mass
spectrometer to distinguish,
detect, and/or record ions with
different masses by means of
their corresponding TOFs.
• m/m will be affected by:
– The energy and angular
spread of emitted ions
– Sampling rate
m/m= t/2t
CRIA: dt=2ns
– Electronic noise
FWHM: full width at half maximum
Arcing
•
Electric field required for arcing in a neutral dielectric given by Paschen’s
Law. Nonlinear function of pressure and gap distance.
Expected Impacts
For randomly tumbling object. Per NASA Technical Memorandum 4527, p.7-3
Possible Questions
• What is the elemental composition of cosmic dust?
• What is the dust flux and its mass dependence?
• What direction is the dust coming from?
• What are the differences in composition and size
between interstellar and interplanetary dust?
Schedule
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Dongwon Lee