Regolith Materials

Sheila A. Thibeault1, Richard L. Kiefer2, Myung-Hee Y. Kim2,

Janet L. Chapman2, J. Adam Weakley2, and D. Ryan McGlothlin2

1NASA Langley Research Center, Hampton, VA2College of William and Mary, Williamsburg, VA

2003 National Educators’ Workshop

Hampton and Newport News, VA

October 19 - 22, 2003

Goals

In-Situ Resource Utilization

- using regolith

In-Space Manufacturing

- fabricating materials

Radiation Protection Methods

- developing habitat concepts

Radiation Physics

- measuring radiation transmission

ProblemMartian Environment• Low-intensity energetic heavy-ion flux of Galactic Cosmic

Radiation (GCR)• Solar Particle Events (SPE)• Neutron radiation• Global dust storms (wind speed = 17-30 m/sec)

Mars Exploration Fact• Earth return possible at specified times (~ every 26 months)

Need habitat to provide safe haven for human

explorers

Martian Regolith(Viking Lander Data)

Average Density 1.4 g/cm3

Chemical Composition 58.2% SiO2

23.7% Fe2O3

10.8% MgO 7.3% CaO

Predicted Annual Dose Equivalent Behind Martian Rocks and Martian Regolith

(cSv/yr)

Thickness g/cm2

Basalt

Lherzolite

Clino-pyroxenite

Ortho-pyroxenite

Dunite

Martian Regolith

1 132.3 132.3 132.4 132.2 132.4 132.3

5 111.5 111.4 111.8 111.1 111.8 111.5

10 94.0 93.8 94.3 93.4 94.3 93.9

30 64.8 64.6 65.2 64.2 65.2 64.8

50 56.5 56.2 56.8 55.9 56.8 56.5

Predicted Biological ResponsesBehind Martian Regolith and Aluminum

After 1-Year GCR Exposure

Thickness g/cm2

C3H10T1/2 Cell Death Rate, %

C3H10T1/2 Cell Transformation Rate, x 10-3 %

Excess Harderian Gland

Tumor Prevalence, %

Martian regolith 1 3.92 1.74 3.50 5 3.28 1.65 3.28

10 2.74 1.54 3.02 30 1.89 1.34 2.63 50 1.65 1.29 2.56

Aluminum

1 3.94 1.76 3.57 5 3.33 1.70 3.37

10 2.80 1.59 3.12 30 1.91 1.39 2.73 50 1.65 1.33 2.63

Predicted Biological Responses Behind Various Materials After 1-Year GCR Exposure

x, g/cm2 x, g/cm2

(a) Dose Equivalent (b) Excess Harderian Gland Tumor Prevalence

H,

cSv

/yr

Exc

ess

Pre

vale

nce

, %

Fabrication of Shielding and Habitat Componentsfor Ground Tests

LaRC-SI RegolithSimulant Powder

Mix De-aerated at 71-77C

under Vacuum

Mold

Mixed Powder

Press or OvenBulk-Molded

Microcomposites

Polymer Regolith Powder

Habitat Construction/Radiation Shieldingfor Martian Exploration and Development

n, p+,.., ++,.., C+6,.., O+8,.., Mg+12,.., Si+14,.., Fe+26

Regolith/LaRC-SI(80%/20% by weight)microcomposite block

Manufacturer: PanasonicModel #: NN-S950Oven size: 14" x 23 7/8" x 19 1/2" (h x w x d)Cavity size: 11" x 18 1/2" x 18 1/2" (h x w x d)Output: 1300 W at 2.45 GHz

Microwave Oven

Ceramic Mold for Microwave Processing

wt% LaRC-SI

Mas

s L

oss

Tem

per

atu

re,

ºC

Gla

ss T

ran

siti

on

Tem

per

atu

re (

Tg),

ºC

TGA Mass Loss and TMA Glass TransitionTemperatures for Regolith/LaRC-SI Microcomposites

0

0.5

1

1.5

2

2.5

5 wt% PE 7 wt% PE 10 wt% PE 15 wt% PE 20 wt% PE Pure PE

Str

en

gth

, ks

iCompressive Yield Strength

for Regolith/PE MicrocompositesCrosshead speed

0.05 in/min

0.008 in/min

0

0.5

1

1.5

2

2.5

3

5 wt% PE 7 wt% PE 10 wt% PE 15 wt% PE 20 wt% PE Pure PE

Str

en

gth

, ks

iUltimate Compressive Strength

for Regolith/PE MicrocompositesCrosshead speed

0.05 in/min

0.008 in/min

0

100

200

300

400

500

600

700

800

900

5 wt% PE 7 wt% PE 10 wt% PE 15 wt% PE 20 wt% PE Pure PE

Mo

du

lus

, ks

iCompressive Modulus

for Regolith/PE MicrocompositesCrosshead speed

0.05 in/min

0.008 in/min

100

105

110

115

120

125

130

5 wt% PE 7 wt% PE 10 wt% PE 15 wt% PE 20 wt% PE Pure PE

Tg, o

CTMA Glass Transition Temperature

for Regolith/PE Microcomposites

TMA Softening Temperaturefor Regolith/PE Microcomposites

80

90

100

110

120

0 20 40 60 80 100 120

Percent Polyethylene

Te

mp

era

ture

(d

eg

. C)

TGA 5% Mass Loss Temperaturefor Regolith/PE Microcomposites

360

370

380

390

400

410

420

0 20 40 60 80 100 120

Percent Polyethylene

Te

mp

era

ture

(d

eg

. C)

BNL-AGS/NASA Shield Test Facility

NASA Beam Line

Experimental Radiation Shielding Effectiveness of Various Materials for 1.06 GeV Fe Ions

0

0.5

1

1.5

2

2.5

3

3.5

4

Al

PE

C

Gr/Ep

Reg/PE

Ep

Fraction dose

reduction per g/cm2

Experimental Setup of 88" Cyclotron at LBNL

Proton beam line

Lexan collimator d3mm1 Target PSD1X&Y d5mm1

• Nearly Monoenergetic Proton Beam (34.5 0.266 MeV) • E-Spectrum without Target (23.68 0.46 MeV)• Statistics (on the order of 1-2 Million Events)

Transmitted Differential Proton Energy Spectrumfor 55-MeV Proton Beam (2.01 g/cm2 thick targets)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

28 29 30 31 32 33 34 35

E, MeV

f (E

), p

roto

ns

/Me

V

Regolith/LaRC-SI 80/20 wt %Regolith/LaRC-SI 60/40 wt %

0

100

200

300

400

1.E+07 1.E+08 1.E+09 1.E+10

Fluence of the beam, protons/cm2

Nu

mb

er

of

err

ors

on

SR

AM

Specimen 102

Specimen 101

SEU on Motorola MCM6246-5V SRAM from 55-MeV Proton Beam

Specimen 102: 80% regolith/20% LaRC-SISpecimen 101: 60% regolith/40% LaRC-SI

Langley Fast Neutron Shield Test Facility

Neutron/GammaSpectrometer

Neutron Absorbing Test Cell

Am-BeNeutron Beam

Ultimate Compressive Strengthfor Regolith/LaRC-SI Microcomposites

Regolith/LaRC-SI60/40 wt%

Regolith/LaRC-SI80/20 wt%

0

5

10

15

20

25

30

35

40

Baseline Proton exposed Neutron exposed Baseline Proton exposed Neutron exposed

Str

en

gth

, ks

i

Compressive Modulusfor Regolith/LaRC-SI Microcomposites

Regolith/LaRC-SI60/40 wt%

Regolith/LaRC-SI80/20 wt%

0

200

400

600

800

1,000

1,200

1,400

1,600

Baseline Proton exposed Neutron exposed Baseline Proton exposed Neutron exposed

Mo

du

lus

, ks

i

Multilayered Habitat Concept

Regolith constructionNeutron slowing-down

Neutron stoppingPressure containment