The fidelity of lunar simulants as compared to actual regolith is evaluated using Figures of Merit (FOM) which are based on four criteria: Particle Size, Particle Shape, Composition, and Density of the bulk material. In practice, equipment testing will require other information about both the physical properties (mainly of the dust fraction) and composition as a function of particle size. At Glenn Research Center (GRC) we are involved in evaluating a number of simulant properties of consequence to testing of lunar equipment in a relevant environment, in order to meet Technology Readiness Level (TRL) 6 criteria. Bulk regolith has been characterized for many decades, but surprisingly little work has been done on the dust fraction (particles less than 20 micrometers in diameter). GRC is currently addressing the information shortfall by characterizing the following physical properties: Particle Size Distribution, Adhesion, Abrasivity, Surface Energy, Magnetic Susceptibility, Tribocharging and Surface Chemistry/Reactivity. Since some of these properties are also dependent on the size of the particles we have undertaken the construction of a six stage axial cyclone particle separator to fractionate dust into discrete particle size distributions for subsequent evaluation of these properties. An introduction to this work and progress to date will be presented

Street, Kenneth W.

NASA Technical Reports Server

1National Aeronautics and Space Administration
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Lunar Dust Characterization Activity at GRC
Kenneth W. Street
Lunar Dust Filtration and Separations Workshop
Ohio Aerospace Institute
November 18 –
 
20, 2008
Abstract
The fidelity of lunar simulants
 
as compared to actual regolith is evaluated using Figures of Merit (FOM) 
which are based on four criteria: Particle Size, Particle Shape,
 
Composition, and Density of the bulk 
material.  In practice, equipment testing will require other information about both the physical properties 
(mainly of the dust fraction) and composition as a function of particle size.  At Glenn Research Center 
(GRC) we are involved in evaluating a number of simulant
 
properties of consequence to testing of lunar 
equipment in a relevant environment, in order to meet “Technology Readiness Level (TRL) 6”
 
criteria.  Bulk 
regolith has been characterized for many decades, but surprisingly little work has been done on the dust 
fraction (particles <20 micrometers in diameter).  GRC is currently addressing the information shortfall by 
characterizing the following physical properties: Particle Size Distribution, Adhesion, Abrasivity, Surface 
Energy, Magnetic Susceptibility, Tribocharging
 
and Surface Chemistry/Reactivity.  Since some of these 
properties are also dependent on the size of the particles we have undertaken the construction of a six 
stage axial cyclone particle separator to fractionate dust into discrete particle size distributions for 
subsequent evaluation of these properties.  An introduction to this work and progress to date will be 
presented.
https://ntrs.nasa.gov/search.jsp?R=20090004866 2019-08-30T06:00:31+00:00Z
2National Aeronautics and Space Administration
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Kenneth W. Street
Biography
Dr. Street, a Senior Research Scientist, joined the staff of the
 
NASA Glenn Research Center 
in February 1991 in the Environmental Programs office where he ran a chemistry laboratory 
analyzing a variety of samples such as water, paint, fuels, etc mainly looking for hazardous 
components.  During that time, he did research on materials to remove toxic metals from 
water and was awarded a patent for invention of a novel ion exchange material. Presently, he 
is involved in research on friction and lubrication in the space
 
environment, development of 
new classes of liquid space lubricants and employs optical spectroscopy to analyze the 
lubricants and wear materials.  Concurrent with this effort is the characterization of physical 
properties of lunar regolith (dust) and simulant
 
materials.   He was also the lead investigator 
on the development of nano-carbon materials (nanotubes
 
and nanoonions) as advanced 
lubricants.  He has participated in many programs throughout the
 
center and has analyzed a 
wide variety of materials including Teflon from the Hubble space
 
telescope and Egyptian 
antiquities from the Cleveland Museum of Art.  Dr. Street earned
 
his Bachelor’s degree in 
chemistry from the University of Connecticut in 1970; and a Master’s degree in chemistry 
from Cleveland State University in 1973.  He received his Doctorate in 1977 from Wayne 
State University. Dr. Street is the author or co-author of approximately 80 papers in the areas 
of tribology, chemical analysis, pharmaceutical analysis, and instrumentation evaluation and 
in 1996 and 1997, was nominated for the NASA Inventor of the Year Award.
He is a member and officer of several professional societies: American Chemical Society, 
Society for Applied Spectroscopy, and Sigma Xi (research society). 
3National Aeronautics and Space Administration
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Lunar Dust Characterization Activities at
Presented By: 
Ken Street (RXN)
NASA -
 
GRC
Presented To:
NASA –
 
NASA Lunar Dust Filtration and Separations Workshop
November  18, 2008
4National Aeronautics and Space Administration
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Agenda
ETDP –
 
Dust Management Project  (WBS 1.4.1 & 1.4.3)
IR&D –
 
High Fidelity Lunar Simulants for Exploration Risk Reduction
ETDP –
 
HRS Surface Mobility  (Running gear & Terramechanics)
NESC –
 
“Proactive Dust Risk Mitigation”
NESC –
 
Tribocharging
LASER/ROSES –
 
Various Proposals
5National Aeronautics and Space Administration
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ETDP –
 
Dust Management
 WBS 1.4.1 & 1.4.3
1.4.1 –
 
Regolith Characterization 
(a.k.a Putting cart prior to horse)
1.4.3 –
 
Simulant Development
Simulant Development (MSFC)
Simulant Characterization (GRC)
MSFC Efforts:
FOMs -
 
particle size
 
and shape
 
distribution, composition & Density
GRC Efforts:
particle size
 
and shape distribution
 
surface area
adhesion
 
abrasion (UC-Boulder)
friability and elasticity
 
surface energy
magnetic susceptibility (WU in St. Louis)
 
dielectric function & conductance
tribocharging
 
charge capacity and electrostatics
surface chemistry and reactivity (ARC & GRC)
6National Aeronautics and Space Administration
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•
 
particle size distribution (PSD) –
 
Paul Greenberg, numerous GRC sizing instruments
•
 
particle shape distribution –
 
KSC may have equipment (Lack of funding)
•
 
surface area –
 
GRC on new IGC (Lack of funding)
•
 
adhesion –
 
James Gaier’s LDAB & Miyoshi pin-on-plate Rig
•
 
abrasion –
 
Ryan Kobrick, UC-Boulder Scratch Tester (2 body); Polishing Experiment (3-body like MSFC)
•
 
friability and elasticity –
 
(Lack of funding)
•
 
surface energy –
 
Allen Wilkinson IGC
•
 
magnetic susceptibility –
 
Da-Ren Chen, Washington University in St. Louis
•
 
dielectric function and conductance –
 
(Lack of funding)
•
 
tribocharging –
 
Barry Hillard (Mars Tribocharging facility)
•
 
charge capacity and electrostatics –
 
(Lack of funding)
•
 
surface chemistry and reactivity:
–
 
GRC had capabilities through IR&D (Randy Vander Wal)
–
 
ARC building capabilities (Farid
 
Salama)
Original list of most important -
 
Top 5:
1.  Particle size distribution
2.  Adhesion
3.  Abrasion
4.  Tribocharging & electrostatics
5.  Surface chemistry & reactivity (especially corrosion) 
ETDP –
 
Dust Management
 WBS 1.4.1 & 1.4.3
7National Aeronautics and Space Administration
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The Elusive Cyclone Separator
Currently working at GRC in pre-production mode!
It should be able to process pounds per day
It is spec’d
 
to give fractions: 
11 –
 
20 micrometer (u)  [Assumes feed sieved to 20 um]
1 –
 
11 u
500 –
 
1000 nanometer (nm)
284 –
 
500 nm
100 –
 
284 nm
40-100 nm
Production of fine materials with narrow PSDs
Characterization of property as a function of PSD
8National Aeronautics and Space Administration
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Multistage Axial Flow Cyclone Separator
Tangential Design
11μm stage
1μm stage
500 nm stage
280 nm stage
100 nm stage
40 nm stage
Multi-Stage Cyclone 
Separator
141 Torr
22 Torr
Cyclone Generator
Complete Stage
9National Aeronautics and Space Administration
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Determining Particle Size Distributions
•
 
Basic approach: determination of 
aerodynamic transport diameters.
•
 
2.5 –
 
700 nm range characterized by 
Differential Mobility Analysis.
•
 
-
 
Scanning Mobility Particle Sizer 
(SMPS) with Condensate Particle 
Counter (CPC) detector.
•
 
700 nm –
 
20 μm range characterized by 
Aerodynamic Particle Sizing (APS).
•
 
Both techniques are sequential, and 
require no a priori assumptions about 
the expected particle size distribution 
function.
•
 
Direct dry-phase aerosolization 
accomplished through the use of a 
Small Sample Particle Disperser 
(SSPD).
APS
Overpressure 
filter
SMPS CPC
Pump
SSPD
EAS
Data Acquisition
and Control
10
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Determining Particle Size Distributions
Cummulative Number Density
PSG 06/03/2008
Aerodynamic diameter (nm)
100 1000 10000
C
u
m
m
u
l
a
t
i
v
e
 
n
u
m
b
e
r
0.0
0.2
0.4
0.6
0.8
1.0
Sample #6
Sample #1
JSC1A
10084
70051 
NU-LHT-1D
Simulants capable of replicating 
nanoscale particles present in 
regolith samples.
(<20 μm)
11
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Collection of nm Sized Particles
•
 
DMA classification column tuned to 
fixed size passband.
•
 
Emerging particles have a defined 
charge state, allowing collection by 
electrostatic focusing.
100 
nm
20 nm
50 nm
500 nm
12
National Aeronautics and Space Administration
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Adhesion
Miyoshi’s Rig
~10-14
 
Torr
Atomically
 clean
diamond
Atomically
 clean
sapphire
Diamond with 
adsorbed species
Sapphire with 
adsorbed species
0
0.5
1
1.5
2
2.5
3
3.5
Surface Condition
Adhesion 
(pull-off 
force), mN
Clean
Air Exposed!
13
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Adhesion Testing
Lunar Dust Adhesion Bell-jar (LDAB)
Testing the adhesion of dust on
thermal radiators in a relevant 
environment
14
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Magnetic Susceptibility of Individual Grains
 (Washington University in St. Louis)
•
 
Method A:  Size of 
particles pre-screened 
using differential mobility 
separator, and field 
sequentially increased 
until  particles are trapped 
within the device.  
•
 
Method B:  Disperse 
sample is introduced, and 
exiting size distribution 
determined while 
sequentially increasing 
field strength. 
15
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Tribocharging
Abrasion testing for Mars Pathfinder
Wheel from Marie Curie in Mars  environment
Wheel charged readily
Potential spiked > 300 volts positive
Tray charged negative
Wheel coated and caked with simulant
Data return for abrasion was very poor
Tribo-charging resulted in heavy dust adhesion
With Lunar simulants and hard vacuum
Expect wheel to be covered with dust
Charge to TBD levels
16
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Surface Chemistry and Reactivity  (GRC)
Done with IR&D Funding
Four Activation Types:
Plasma
Chemical
Thermal
Mechanical
Fig 1
17
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Surface Chemistry and Reactivity  (GRC)
Activation as monitored 
by deactivation
18
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Surface Chemistry and Reactivity  (GRC)
Activation vs Depth into sample
0
1000
2000
3000
10 mm 20 mm 30 mm
Depth Below Surface
R
e
s
i
s
t
a
n
c
e
 
(
M
 
o
h
m
s
)
Plasma Activation
Thermal Activation
6x10
9
4
2
0
R
e
s
i
s
t
a
n
c
e
 
(
o
h
m
s
)
860840820800780760740
Temperature (K)
 Resistance without H2
 Resistance with H2
 Fitted Resistance without H2
 Fitted Resistance with H2
Activation of JSC1AF
020107
Ea = 10.2 J/mole
Ea = 19.3 J/mole
Thermal
Thermo chemical
19
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Surface Chemistry and Reactivity  (GRC)
What we do know:  
We are doing something to the samples
What we don’t know:  
Pretty much the rest!
For a given material, a given method has reproducible
deactivation.
For a given activation method, different materials have
different deactivation profiles.
Between activation methods, same material gives different
deactivation profiles.
-
 
What does change in conductivity relate to chemically?
-
 
How do we account for surface area?
-
 
How do we account for electrode contact?
-
 
How do we quantify % of surface modified?
-
 
How do we tell what kind of modification occurred?
20
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Surface Chemistry and Reactivity  (ARC)
Activate particles in chamber
Probe surface spectroscopically
Gives chemical change 
information about surface
21
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Abrasion –
 
2 Body (CU-Boulder)
Anorthositic Tip
Diamond tip across Al 6061-T6
22
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Abrasion –
 
3 Body (CU-Boulder)
ASTM G-174
An alternative is the MSFC developed “Polishing Wheel”
 
experiment
23
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Surface Energy
Inverse Gas Chromatography
Unknown Stationary Phase
Known Eluents (Probes)
Hydrocarbon series
Dichloromethane
Acetone
Ethyl Acetate
Acetonitrile
Ethanol
15
20
25
30
35
40
45
50
55
60
65
D
i
s
p
e
r
s
i
v
e
 
S
u
r
f
a
c
e
 
E
n
e
r
g
y
 
(
m
J
.
m
-
2
)
JSC-1a-Bag JSC-1a-Bottle JSC-1a-Bottle-Preheated to 100 °C
Sample
Figure 1: Dispersive component of the surface energy for the samplesDispersive
 
Surface Energy (mJ/m2)
J C-1AJSC-1A JSC-1A dry
Assumes  ΔG = ΔH
Probes measure Dispersive (HCs
 
and 
Polar (H bonding, Acid/Base) Forces
24
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Composition (GRC)
Glass
X-ray Diffraction of 2 Different JSC-1A Samples
< 10 um
< 20 um
25
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Contamination from Grinding
ICP Data for Trace Element Contamination
•
 
An Inductively Coupled Plasma (ICP) analysis 
was performed on the feedstock material and 
the dust simulants to quantify the amount of 
contamination introduced during grinding
•
 
Mill had a tungsten carbide liner, so the 
expected contaminants are tungsten (W), 
nickel (NI), and cobalt (Co)
•
 
All of the expected contaminants were 
measured in the prototype lunar dust 
simulants
–
 
The amount of contaminant increased 
with grinding time
–
 
Although observable, the overall level 
of contamination does not appear to be 
a significant problem.
Element JSC-1A Feedstock
Dust Simulant 
#1
Dust Simulant 
#6
W 0 ppm 30 ppm 170 ppm
Ni 110 ppm 120 ppm 120 ppm
Co 60 ppm 100 ppm 100 ppm
Composition (GRC)
26
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oxygen map
Iron
 
Map
Oxygen MapSilicon Map
Gatan image filter (GIF) 
maps using electron 
energy loss spectroscopy.
200 nm
20 nm
TEM Images of a Simulated Agglutinate:
 
embedding of nanophase Fe0
 
globules
Composition (GRC)
27
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Concluding Remarks
Dust Management Project team is charged by NASA to be 
the “go-to”
 
place for definitive answers on how physical 
properties of simulants  relate to lunar regolith properties 
for verification of material and component performance of 
lunar equipment, habitat, seal behavior, etc. in order to 
reduce risk to safety, mission, cost, etc.
Having this information centered in the government 
reduces the risk of proprietary restrictions fogging the 
fundamental understanding of simulant behavior in lunar 
simulation projects.
28
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Thanks for your attention.
Any Questions?


Lunar Dust Characterization Activity at GRC

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