Long-term Lunar Radiation Degradation Effects on Materials · 5 The Boeing Company, Houston, TX...

Long-term Lunar Radiation Degradation Effects on Materials

Kristina Rojdev i , Mary Jane O'Rourke, Steve Koontz, John Alred 2, Charles Hill', RodrigoDevivar3 , Shakira Morera-Felix 4 William Atwell s , Steve Nutt, Leslie Sabbann7

'NASA Johnson Space Center, Houston, TX 77058 (PhD Candidate, USC)2NASA Johnson Space Center, Houston, TX 77058

3ESCG — Jacobs Engineering, NASA Johnson Space Center, Houston, TX 770584ESCG — Hamilton Sundstrand, NASA Johnson Space Center, Houston, TX 77058

5 The Boeing Company, Houston, TX 770596University of Southern California, Los Angeles, CA 90089'Michigan Technological University, Houghton, MI 49931

Abstract

The National Aeronautics and Space Administration (NASA) is focused on developingtechnologies for extending human presence beyond low Earth orbit. These technologies are toadvance the state-of-the-art and provide for longer duration missions outside the protection ofEarth's magnetosphere. One technology of great interest for large structures is advancedcomposite materials, due to their weight and cost savings, enhanced radiation protection for thecrew, and potential for performance improvements when compared with existing metals.However, these materials have not been characterized for the interplanetary space environment,and particularly the effects of high energy radiation, which is known to cause damage topolymeric materials. Therefore, a study focusing on a lunar habitation element was undertaken toinvestigate the integrity of potential structural composite materials after exposure to a long-termlunar radiation environment. An overview of the study results are presented, along with adiscussion of recommended future work.

To be subnutted for:National Space and Missile Materials SymposiumScottsdale, AZJune 28 — July 2

https://ntrs.nasa.gov/search.jsp?R=20100021146 2020-06-27T18:50:24+00:00Z

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A-t 4-1.,19 Outline0 Introduction• Background -Radiation• Methodology and Test setup• Some Project Results• Ongoing Work• Questions

National Space and Missile Materials Symposium 2010Scottsdale, AZJune 28-July 1 2

INTRODUCTION

'.L

Introduction

is NASA is focused on technologies that willextend human presence beyond low earthorbit (LEO)— To advance state of the art— To provide for longer duration missions

outside LEO

• Focus: materials for long-term surfacehabitation


A-t I-I.,19

Motivation/Purpose

Long-term surface habitation requires largestructures that must withstand theenvironment for the duration of the missionsFiber reinforced composites have gainedinterest— Potential weight savings— Potential enhanced radiation protection for the

crew and electronics— Potential for infusing cutting edge research

National Space and Missile Materials Symposium 2010Scottsdale, AZ

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0

June 28-July 1 5

A-t I-I.,19

Problem/Objectives

• Problem: comaosite materials have notbeen characterized for the space radiationenvironment, which is known to causedamage to polymeric materials

• Objective: assess composite durability in asimulated long-term lunar radiationenvironment


'.L

Assumptions

n The habitat is unshielded from radiation on theexterior

There is some multi-layer insulation andmicrometeorite/surface ejects shielding, but no galacticcosmic ray shielding (i.e. covering the habitat underregolith)

• The habitat will remain on the surface and be inservice for 30 years

• The habitat is pressurized with air at an elevatedoxygen concentration

• The habitat is exposed to one large solar particleevent during each solar cycle and constant galacticcosmic ray exposure


BACKGROUND

'.L

A-t I-I.,19Background —Radiation Environment

So lar win

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protons-Auroral electrons

101

-5 1011

^^yy

10 "CI

1x

Trapped electronsTrappedi protonsinner zone)

.t

Sol ar flareprotons

Galact ic cosm i c ray s

VOrapped Protonu ter zone

Solar stubprotons

10-4 1 100

102 104

Concerned with high.nasa.jzov/sections/section05.htm energy particle radiation


Dominant Radiation on the Lunar Surface

Q

400000

350000

300000l7vW 25000000

200000

150000

100000

5000C

c

n GCR Dose

n SPE Dose

GCR vs. SPE exposure

500000

450000

30 yr

Mission Lifetime

National Space and Missile Materials Symposium 2010Scottsdale, AZ 10June 28-July 1

QDoses Materials will See Due to this

_ Radiation ExposureDose to Materials over mission

1.00E+10

Conventional (averaged GCR exposure, 1 large SPE per solar cycle, and FS of zo)composites failure

ff Non-Exposed Lunar Dose (cGy)

n Exposed Lunar Dose (cGy)

Need to find reference to the above dataTeflon and Silicon

material failure

visible damage begins to

occur in some plastic

materials

i.00E+og

i.00E+o8

1.00E+07

1.00E+o6

vv i.00E+05Ln00

i.00E+04 ,-

1.00E+o3

1.00E+oz

1.00E+os

i.00E+oo Eio year zo year 3o year

Mission Lifetime (years)


Radiation Effects on PolymericMaterials

• Previous radiation research on polymers is mainlyelectron radiation or gamma radiation

• Cross-linking — bonds that link one polymer chain toanother through chemical reaction— Pro: increases stiffness of material, potentially making it stronger— Con: if the stiffness is increased too much, the material becomes

brittle and easily fractured• Chain scission — a chemical reaction that breaks the

bonds of the backbone polymer chain— Con: weakens the polymer strength


'.L

METHODOLOGY AND TESTSETUP

Experimental MethodologyMaterial 1: Material 2: Material 3:

Boron/carbon mix Carbon fiber High modulus Polypropylene fiber

Group 1: Control(no tension, no

radiation exposure)

Group 2: Tensiononly (no radiation

exposure)

Group 3: Tensionand radiation

exposure

Group 4: Control(no tension, no

radiation exposure)

I& ---------- a

Group 5: Radiationonly (no tension)

Group 6: Tensionand radiation

exposure

National Space and Missile Ma ais symposium 2010Scottsdale, AZJune 28-July 1

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,%

W&T T

Radiation Beam

A-t I-I.,19

Radiation Test Setup

Strain gauge in center of sample — Sample in Test

Beam Exitgather a pre-exposure and post- Stand

exposure reading


Characterization Completed

Non-Destructive '.n C-scan• Fourier Transform Infrared Spectroscopy (FTIR): bulk chemical

composition• Raman Spectroscopy: bulk chemical composition (better for Carbon)• Scanning Electron Microscopy (SEM): look at surface for visual

changes


Characterization CompletedDestructive• Tension: tensile stress, strength, strain, ultimate strain, chord modulus,

poisson's ration, stress vs. strain• Flexure: Flexural stress, strength, offset yield strength, chord modulus,

strain, tangent modulus of elasticity, secant modulus, stress vs. strain• Dynamic Mechanical Analysis (DMA): Creep and/or stress relaxation

information• Gas Chromatography - Mass Spectrometry (GCMS): analysis of compounds

and molecular weight information• Optical microscopy. look at edge of sample to gather fiber volume fraction

and porosity• Thermogravi metric Analysis (TGA): weight change as a function of timen Differential Scanning Calorimetry (DSC): heat capacity as a function of

temperature, and changes in glass transition temperaturen Post-Fracture Analysis: Scanning Electron Microscopy (SEM): look at fracture

edge after tension/flexure tests


'.L

SOME PROJECT RESULTS

'.LFTIR Procedure

• Before radiation exposure, eachsample was characterized by FTIRin 9 locations

• After radiation exposure, eachsample was again characterized byFTIR in the same 9 locations

• The pre-exposure scan wassubtracted from the post-exposurescan to better locate new signalsobserved after radiation exposure


o°

FTIR Results —Boron/Carbon

Potential supporting evidence for destruction ofaromatic network structure.

0.0045-

Increase inIncrease in C-H

0.0040- stretchHydroxyl band

0.0005- Increase in C=C=C0.0030—

IItype of structure

0.0025-_ 1

0.0020—

0.0015— ^^ ^^^ ^I I flI l,a ^I

O.FIA10

0.0005-

o.onoo-

3800 3600 40 3200 3000 2800 2600 ?400 2200 ?000 1800 1600 1400 1200 1000 BoCi h,`.Navenurnher

0

0 00210

0.0015-4

-2 0.0010-1

0.000510.0000-

-00005a

9 A-t

FTIR Results — Boron/Carbon

Aromatic structure is intact and no other structural

changes are visible.

. . . . .. , , , , , * 2 - ' i ^ . i - - i - - ' i ' ' ' O' 8106 6^7^800 -1600 i400 3200 , -i^oo, ^8'no -;6,06 ^4,17)h 2206 000 am 600 - - 400 ' • ^Oh200

Wavenumbet

A-t I-I., ".9FTIR Results -Carbon

Aromatic structure is intact and no other structuralchanges are visible.

0.0012—•

0.0o10- +

0,0008-IV q

0.0006— I ^I

Cl. 0004— ; '. II yl ''Ii

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3860 3600 3400 32003000 2800 26x0 2400 2200 2Go0 i8G0 7600 i400 1200 1GG 0 6°d'i'denUITIber

• 3 coupons made from one sample-coupons were cut perpendicular to0° plys

• to highlight any matrixsensitivities in tensile properties

• Each tensile coupon included• tabs to protect the materialduring test• single strain gauge in thecenter to collect tensile data

A-t I-I., ".9

Tensile Test Procedure

Tensile Results —Boron/Carbon

Corrected Stress vs. Strain for all coupons600

500

400

^aa.

y 300

a^

200

100

0

0.00E+00

G1-1— G1-2

• G1-3^G2-1

G2-2• G2-3

—G3-1G3-2

• G3-3G4-1G4-2

• G4-3G5-1G5-2

• G5-3G6-1G6-2

2.00E-03 4.00E-03 6.00E-03 8.00E-03

1.00E-02 1.20E-02

strain (in/in)

National Space and Missile Materials Symposium 2010Scottsdale, AZJune 28-July 1

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SEM of Fracture Edge —Boron/Carbon

Control — Surface Micrograph Radiation and Tension — SurfaceMicrograph


• G1-1

G1-2

-G1-3

'G2-1

• G2-2

G2-3

G3-1

— G3-2

• G3-3

G4-2

• G4-3

^G5-1

G5-2

• G5-3

900

800

700

600

^a500

400

W

300

200

100

Tensile Results —Carbon

Corrected Stress vs. Strain for all coupons

i

i

i

TOO

0

0.00E+00 2.00E-03 4.00E-03 6.00E-03 8.00E-03 1.00E-02

Strain [in/in]


120E-02 1.40E-02 1-60E-02 180E-02

Ongoing Work

• Continued data analysis of couponsalready characterized

• Anew study looking at the dose rateduring radiation exposure and its effect

• Anew study looking at how irradiatedcomposites respond to hypervelocityimpacts


A-t I-I.,19

Summary —Boron/Carbon

• FTIR

— Possible evidence of destruction of aromaticnetwork structure

— Possible evidence of oxidative degradation

• Tensile— Possible evidence of enhanced cross-linking

of the matrix

• SEM— Possible evidence of surface damage


A-t I-I., ".9

Summary -Carbon

0

0

FTIR— No evidence of changes yet

Tensile—Possible evidence of enhanced cross-linking

of the matrix

Conclusions and Future Work

• Data shows that something is changingthe material properties, even though it isinconsistent at this point

• Continue to analyze collected data• Further work needs to be completed

—Validate repeatability of data

—Increase data sets for statistical significance

— Control variables of time and environmentbetter

A-t I-I.,19

Acknowledgements

• Lab Staff at NASA-JSC• Materials and Processes Branch at NASA-JSC• University of Southern California• The Boeing Company


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