Dr. Andy Hollerman

1
The Search for New NASA-Based Impact Sensors
Using Fluorescent Materials
Dr. Andy Hollerman Associate Professor of
Physics University of Louisiana at
Lafayette Lafayette, Louisiana 70504 NSF/RISE
Workshop/Short Course Development Study of
Advanced Sensors Sensor Materials Alabama AM
University, Normal, Alabama July 16, 2008
2
Collaborators

• Ross Fontenot, Brady Broussard, and Brandon Payne
• Department of PhysicsUniversity of Louisiana at
  LafayetteLafayette, Louisiana 70504
• Stephen W. Allison and Mike Cates
• Measurement Science and Systems Engineering
  DivisionOak Ridge National LaboratoryOak Ridge,
  Tennessee 37831
• Daryush Ila and Claudiu Muntele
• Center for the Irradiation of Materials
  (CIM)Alabama AM UniversityNormal, Alabama
  35762
• David L. Edwards
• Natural Environments Branch (EV13)NASA Marshall
  Space Flight CenterHuntsville, Alabama 35812
• Peter Wasilewski
• NASA Goddard Space Flight CenterAstrochemistry
  Branch Code 691Greenbelt, Maryland 20771

• Noah Bergeron and Chester Wilson
• Institute for MicromanufacturingLouisiana Tech
  UniversityRuston, Louisiana 71272
• Shawn Goedeke
• McHale and Associates, IncorporatedKnoxville,
  Tennessee 37919
• Brian Wells
• Space Research InstituteAuburn
  UniversityAuburn, Alabama 36849
• Friedemann Freund
• NASA Ames Research CenterSETI InstituteMoffett
  Field, California 94035

3
Agenda

• Background - Fluorescent Materials
• Triboluminescence Research
• Low Velocity (1-100 m/s)
• Hypervelocity ( 1 km/s)
• Mesovelocity (100 m/s to 1 km/s)
• Radiation Effects Research
• Link to NASA Research
• LCROSS
• Conclusions

4
Introduction
5
Background

• Phosphors became technologically and industrially
  important with the introduction of fluorescent
  lamps in 1938.
• Thermometry use suggested in German patent in
  1938. First peer-reviewed article, to our
  knowledge, appeared in 1949.
• Between approximately 1950 to 1980, it was not
  widely used. Its most common use was for
  aerodynamic applications.
• Advances in lasers, microelectronics, and other
  supporting technologies enabled additional
  commercial as well as scientific uses.

6
Fluorescence Factors

• Dopant (activator) concentration may change the
  phosphor emission spectrum. Dopant concentration
  that maximizes fluorescence varies with dopant
  and host. At high concentrations, the emission
  characteristic lifetime may vary from a simple
  single exponential. Rise times are also affected
  by dopant concentration.
• Characteristic size of phosphor particles affects
  intensity and lifetime of fluorescence when size
  is around 5 µm or less. For Y2O3Eu, e.g., decay
  time increases from 440 to 600 µs when particle
  size decreases from 0.42 to 0.11 µm.
• Impurities Deliberately added rare-earth
  impurities may either increase or degrade
  fluorescence efficiency, depending on how energy
  levels match. The literature contains
  information on which pairings favor enhancement.
• Magnetic Field At least one tesla is usually
  required to observe a change in fluorescence
  spectra and the material must be very cold, say
  20 K.

7
Typical Fluorescence SpectraFor Rare-Earth
Materials
Wavelength (nm)
8
Fluorescence Decay Time
ZnSMn
ZnSMn
t
t

• Temperature sensitivity is often determined
  through the characterization of the prompt
  fluorescent decay time (lifetime - t).
• Sensitivity can range from cryogenic
  temperatures up to approximately 2000 K.
• Phosphor thermometry allows temperature
  measurement through flames and large black body
  backgrounds.

9
Temperature Dependence of Excitation (Y2O3Eu)
Temperature in Kelvin
10
Temperature Dependent Line Position and Bandwidth
11
Rise Time of Y2O3Eu

• It was found that the rise time of Y2O3Eu is
  temperature dependant over a lower temperature
  range than the decay time.
• This effectively increases the range of the
  phosphor.

12
Blackbody Versus Fluorescence Emission
13
Phosphor Sensors

• Phosphors are fine powders that fluoresce when
  excited.
• Many characteristics of fluorescence are
  temperature dependant such as
• Decay Time.
• Rise Time.
• Intensity.
• Absorption spectra.
• Emission peak shape.
• Phosphors have also been shown to emit
  triboluminescence (TL) when struck.
• Previous research has shown that the intensity of
  many phosphor materials decreases with increasing
  proton fluence.

14
Intitial Motivation

• Damage sensors are desired by NASA to minimize
  the probability of future Columbia-like
  disasters.
• Micrometeoroid and ultra high speed
  (hypervelocity) orbital debris impacts pose a
  significant threat to spacecraft.
• Triboluminescence (TL) has the potential to be
  used to detect impacts and other phenomena in
  spacecraft.

15
Triboluminescence Research
Image of the Deep Impact spacecraft hitting comet
Tempel 1 on July 4, 2005. (Triboluminescence?)
16
What is Triboluminescence?

• Triboluminescence (TL) is light triggered by
  mechanical action such as friction or impact.
• TL has been observed in sugar and ceramics for
  several hundred years.
• Examples
• Many minerals, such as quartz, will glow when
  scratched or scraped.
• Sugar emits a blue light when crushed.
• TL is a generic name for several different
  emission mechanisms
• Ionization of gas in the crack of a fracture.
• Direct stimulation due to electrostatic field.
• Stimulation due to recombination of charge.
• Photoexcitation from 1).
• It has been estimated that 30 of organic
  crystals and 50 of inorganic crystals are
  triboluminescent.
• Sometimes referred to as mechanoluminescence (ML).

17
Real Wint-O-Green Lifesavers TL Emission Spectrum
TL Emission from Lifesavers Candy
Hammer Hitting Lifesavers Candy

• Broadband emission from 400 to 500 nm due to oil
  of wintergreen (methyl salicylate).
• Line emission from 300 to 400 nm are due to the
  sucrose (sugar) candy base (nitrogen emission of
  sparking).
• L. Sweeting, Triboluminescence With and Without
  Air, Chemistry of Materials, vol. 13 (3), pp.
  854-870, 2001.

18
Low Velocity TL Research
Apollo 11 landing site on July 20, 1969.
19
Low Velocity TL Apparatus
Diagram
Ball
ZnSMn Powder
v
Impact Area
Light
PMT
PS
Recording Oscilloscope
Side View (PMT)
Complete View
20
ZnSMn TL Intensity Results
ZnSMn Powder

• TL response intensity appears to be a function of
  impact velocity.
• TL light appears to have a threshold of
  approximately 0.5 m/s.
• TL increases rapidly from 0.5 m/s until about 1.8
  m/s.
• Above 1.8 m/s, TL appears to be more like a
  saturation state, where the slope is shallow
  which indicates less sensitivity to impact
  velocity.

21
ZnSMn Emission Spectrum(Four Different
Excitation Sources)
22
Typical TL Response
PMT Output (Volts)
TL at the moment of impact
ZnSMn Powder
Time (ms)

• Drop height 39 inches (1 m).
• These tests were performed without replacing the
  powder lost during the cleaning process.
• Total mass loss per shot of the ZnSMn powder was
  small and did not affect the luminescent
  intensity.
• TL decay appears to follow standard exponential
  decay (t 300 µs).

23
Effects of Repeated Impact

• Low velocity impact on ZnSMn and PPMS paint.
• Repeated Impact of 31 mJ.
• Smooth curve is best-fit line of the data.
• After 20 strikes, the signal was reduced by 6
  volts or 40.
• The signal level stabilized after 20 strikes.

24
Other Tested TL Materials

• These qualitative tests were completed using a
  modified low velocity drop tower.
• Each phosphor powder sample was placed in the
  drop tower sample tray.
• The tube was mounted on top of the tray with a
  release pin.
• These tests were easily reproducible and multiple
  drops were completed to reduce the random error
  of powder loss and any drop height variations.
• Europium tetrakis was the brightest tested
  material
• Europium Tetrakis
• (Dibenzolmethide)-triethylammonium (EuD4TEA)

25
Europium Tetrakis Emission(EuD4TEA)
26
Hypervelocity TLImpact Research
27

MSFC Hypervelocity Research History
All measurements were completed using the two
stage light gas gun located at the NASA Marshall
Space Flight Center (MSFC) in Huntsville, Alabama.
28
MSFC Shot Summary

• Completed at MSFC using the two stage light gas
  gun from March 2004 to January 2006.
• Basis for Noah Bergerons Masters degree that
  was completed in December 2006.

29
MSFC Two Stage Light Gas Gun

• Hypervelocity light gas impact guns use smokeless
  gunpowder to drive a piston that compresses
  hydrogen or helium gas that, in turn, propels the
  projectile to speeds of 1 to 8 km/s.
• The NASA Marshall Space Flight Center (MSFC) two
  stage light gas gun shoots spherical nylon 1.8 mm
  slugs and 1 mm diameter aluminum sabot-encased
  spheres to replicate space debris impacts.

30
Tested Paints

• Poly (phenyl methyl) siloxane (PPMS) -
  polysiloxane Binder
• Techneglas 100F formulation
• Solid dissolved in alcohol (50 PPMS and 50
  alcohol by mass)
• Set by heat treatment at 160 C (crosslink
  polymer).
• Phosphors
• Zinc sulfide doped with manganese (ZnSMn) and
  copper (ZnSCu).
• Phosphor powder was mixed with PPMS liquid in a
  14 ratio by mass and sprayed (using a common
  airbrush) on a small portion of a 12 x 4 x 3/16
  inch thick aluminum plate.

Visible Light Picture of Sample Plate
UV Light Picture (585 nm yellow fluorescence)
PPMS Monomer
31
Test Hardware

• Inexpensive two to one inch rubber PVC adapters
  (purchased at a hardware store) were used to
  shield the detector facing the coating from the
  muzzle flash.
• The lower detector, observing the muzzle flash,
  was used to trigger the upper detector into
  recording TL light.
• The PPMS and ZnSMn paint was mounted on the side
  facing away from the gun.

Mounted painted sample assembly with two
detectors and light shields
Projectile Direction
32
Hypervelocity TL Evidence

• Shot Five (December 2004)
• MSFC two stage light gas gun
• Projectile 1 mm Al sphere (sabot)
• Velocity 5.55 km/s
• TL clearly visible (t 300 µs)
• Two silicon photodiodes (one shielded)

Muzzle Flash (unshielded)
TL Light (shielded)
33
ZnSMn Light Yield Results

• The yield was calculated by integrating TL
  light from the peak to 1 ms after the peak (Dt
  3t).
• Ratio is based on the yield for the 5.54 1.10
  J impact energy being equal to 1.0.
• It appears that the quantity of emitted TL
  light is a function of impact energy.

34
ZnSMn Decay Time Results
35
Faint ZnSCu TL Emission
Muzzle Flash (unshielded)
Faint TL Emission (shielded)

• ZnSCu emits green fluorescence.
• Data collected from shot three during experiment
  six (August 11, 2005).
• Projectile velocity of 5.0 0.5 km/s.

36
Preliminary Gun Flash Spectra
Hydrogen
Helium
v 4.7 0.5 km/s
v 3.3 0.5 km/s

• Light emission from both the hydrogen and helium
  gas loads (blackbody shape) is a maximum (lp) at
  a wavelength of approximately 640 nm
• Equivalent to a blackbody temperature of about
  4,500 K (lpT 2.898 x 10-3 m-K).
• An Ocean Optics S-2000 spectrometer with USB
  interface was used with a fiber optic vacuum
  feedthrough to collect the gun flash spectrum for
  each shot.
• Data was collected using the standard Ocean
  Optics OOIBase32 software in snapshot mode on a
  laptop computer.
• In order to capture spectra, the integration time
  was set to its maximum value (3000 ms) with no
  averaging.
• Spectral data was collected during experiment
  five (March 29, 2005) at MSFC.

37
Mesovelocity TL Results
Standing over 363 feet high with its Apollo 11
spacecraft payload, the Saturn V produced over
7.5 million pounds of thrust at lift-off.
38
NASA GSFC One StageLight Gas Gun
Catch Tank
Sample Chamber
Barrel
39
GSFC One Stage Gas Gun

• Located in building six of the NASA Goddard Space
  Flight Center (GSFC) in Greenbelt, MD.
• Last used for research more than ten years ago.
• Research was revived in summer 2006 by a team of
  students and faculty from UL Lafayette.
• One stage light gas gun
• 2.5 inch (63.5 mm) bore.
• Uses helium or nitrogen gas.
• Projectile speeds
• Variable from 0.2 to 1.2 km/s.
• Each sample and sabot catcher were placed in the
  catch tank.
• Velocity measurement setup was in sample chamber.
• Shot pressure 1 torr.
• Contact Dr. Peter Wasilewski.

40
SGFC Gun Sabots
A
B
C
GSFC 63 mm (2.5 inch) diameter sabots A) 1.2 kg,
B) 0.09 kg, and C) 0.09 kg after impact
41
Gas Gun Sabots(90 g Mass)
Sabot With Foam
Sabot With Mounted Projectile
Aluminum Sabot
42
Inside GSFC Gun
Projectile Trajectory
Inside catch tank looking at sabot catcher with
sample in background
43
Gun Catch Tank
44
Sabot Catcher and Sample Mounting
45
Breech End of Gun
Breech section showing A) high pressure
injector, and B) white Teflon o-ring.
Breech end of the gun looking towards the catch
tank.
Open breech section showing firing pin.
46
Example Results
A
B
Granite samples that were shot A) once (white
visible blemish) and B) twice (small defined
blemishes)
Gabbro sample shot once
Samples hit with a quarter inch diameter (6.3 mm)
steel ball bearing.
47
GSFC Gun Calibration Curve

• Helium gas used to accelerate projectile.
• Sabot mass 0.09 0.35 kg.
• Used three different diameter steel bearing
  projectiles
• Attached to nose of the sabot using common foam.
• Statistics
• 60 shots - summer 2006.
• 52 shots - winter 2007.
• 100 shots - spring and summer 2007.
• GSFC Contact
• Dr. Peter Wasilewski.
• Funding for summer 2006 and 2007 is provided by
  the GSFC Office of Higher Education through the
  NASA ESMD team program.
• Data used for Charles Malespins Masters thesis
  in summer 2007.

48
Accomplishments

• Safety procedures
• Assisted with the development of a checklist to
  safely fire the gun.
• Developed procedures to minimize risks to
  operators and outside building occupants.
• Hardware development
• Designed and built a holder for a variety of
  samples.
• Built and tested a sabot catcher for small target
  projectiles.
• Gun testing and firing
• Completed more than 200 shots (June 2006 to
  August 2007).
• Utilized 0.09 kg and 0.35 kg sabots for
  experiments.
• Fired projectiles with velocities from 0.2 km/s
  to about 1.0 km/s.
• Fire a maximum of thirteen shots per day (four
  shots per day average).
• Assisted with the development of a two-wire
  system to measure speed.
• Assisted with the development of a trigger system
  for data acquisition.
• Data collection
• Acquired current, radio frequency (RF), and light
  emission data for a selection of rock and metal
  plate samples.

49
Damage Examples
Broken Weld
Broken Bolt
Examples of damaged rock samples and sabots.
Broken door flange plate with installed wire for
speed measurement.
50
Example Calibration Data
Close-Up of Light Decay
Time Dependent Emission
Intensity
Intensity
Time (s)
Time (s)

• Run 13 - January 2007.
• Calibration shot of aluminum ball bearing on
  aluminum plate.
• Quarter inch (6.3 mm) diameter aluminum
  projectile.
• Impact speed 350 m/s.
• Detector mounted on front side of the aluminum
  plate.
• Measured light decay time 44 µs.

51
Example ZnSMn Data
Sabot Impact
Projectile Impact (Decay 300 µs)

• Aluminum ball bearing hitting an aluminum plate
  coated with a thin layer of epoxy and ZnSMn
  powder pressed into the surface.
• Quarter inch (6.3 mm) diameter aluminum
  projectile.
• Impact speed 350 m/s.
• Two detectors mounted on front side of the
  aluminum plate.
• Measured light decay time 300 µs.

52
Sabot Catcher Motion
53
Typical Light Emission
54
GSFC Mesovelocity TL Results(Preliminary)

• Measured decay times with detectors on same side
  as the projectiles.
• Incident projectile velocities of 250-400 m/s.
• Projectile diameters of 3-7 mm.
• Results show that it is possible to measure TL
  from ZnSMn from a front side impact
• Complicated by other sources of light.

55
Interesting TL Impact Video

• A few grains of ZnSMn powder was packed into a
  sealed hollowed-out compartment inside a 45
  caliber bullet
• Speed of about 300 m/s.
• Observed with a standard Sony Handycam.
• Distance to target was about 30 yards.
• Bullet hit a stationary aluminum target.

56
Radiation Effects Research
Picture of Earth from the surface of Mars taken
by Pathfinder in 1997. (Mars impact
triboluminescence?)
57
Space RadiationEnvironment

• Vacuum
• Pressure Differentials
• Solar UV Degradation
• Contamination
• Neutral (Neutron Interaction)
• Aerodynamic Drag
• Physical Sputtering
• Atomic Oxygen/Spacecraft Glow
• Plasma (Protons, keV Electrons)
• Spacecraft Charging
• Dielectric Breakdown
• Electrostatic Discharge
• Radiation (Protons, MeV Electrons)
• Electronics Degradation
• Crew Safety Hazards
• Micrometeroid and Other Debris or Particles

Picture of Earth from 30 km taken by a high
altitude balloon.
58
Half Brightness Fluence

• The term half brightness fluence (N1/2) was
  coined as a consistent figure of merit to
  evaluate the effectiveness of a material to emit
  fluorescence as a function of radiation fluence.
• Birks and Black (1950 and 1951) showed
  experimentally that fluorescence efficiency of
  anthracene bombarded by alpha particles varies
  with total fluence.

• Where
• I Mean intensity of fluor light,
• I0 Initial mean intensity of fluor light,
• N1/2 Half brightness fluence, and
• N Total radiation fluence.
• Empirically derived from existing experimental
  data.
• The Birks and Black relation describes the
  deterioration of fluorescence for most
  materials irradiated with protons over the last
  decade.

59
Proton Experiment in Progress(CIM at AAMU)
60
Experimental Apparatus
61
Example N1/2YAGCe and Cellulose Pressed Tablet
This N1/2 is much smaller than the single crystal
or polycrystalline paint values due to pressure
applied during sample preparation.
62
Selected 3 MeV Proton Data
63
MSFC Experimental Facilities(Electron Gun)
Vacuum Chamber
Sample Holder in Chamber
Electron Gun Controls
Fiber Position
Sample Holder
64
20 keV Electron N1/2 Results

• Beam 20 keV electrons
• Current density 0.88 0.03 nA/mm2

• N1/2 (8.17 0.20) x 1013 mm-2
• Irradiation time 10.15 hours

65
Exception PbPO4Eu Glass(6 wt. Eu Sample)

• 3 MeV proton irradiation
• Completed at the Center for Irradiation of
  Materials at Alabama AM University
• Current 600 nA
• Irradiation time 45 min
• Sample temperature 30 C
• Irradiation area 22 mm2
• Cylindrical sample
• Dimmeter 25 mm
• Width 8 mm
• Made by Lynn Boatner at ORNL.
• Over the range of tested fluence (5 x 1014 cm-2),
  the light yield is slowly increasing.

First Data Run (B1)
Fit Slope (1.5 0.4) x 10-16 mm2
Fluence (x 1014 mm-2)
66
Exception PbPO4Eu Glass (6 wt. Eu Sample)
Second Data Run (B2)
Fit Slope (1.3 0.2) x 10-16 mm2
Fluence (x 1014 mm-2)
Over the range of tested fluence (9 x 1014 cm-2),
the light yield is slowly increasing.
67
PbPO4Eu Glass Spectra(6 wt. Eu Sample)
Intensity grows with 3 MeV fluence.
68
Exception PbPO4Eu Glass (8 wt. Eu Sample)
Data Run (B3)
Fit Slope 0 mm2 Emission Output constant
Fluence (x 1014 mm-2)
69
ZnSMn Decay Time Results
3 MeV protons
70
Annealing Effects(3 MeV Protons on ZnSMn Paint)
Fluence 2.28 x 1013 mm-2
Fluence 7.39 x 1013 mm-2

• A comparison of the temperature versus decay time
  curves indicates that proton irradiation changes
  the temperature sensitivity of ZnSMn.
• As the curve for the irradiated sample approaches
  the unirradiated sample, the values begin to
  follow the unirradiated curve.
• There appears to be annealing of the irradiation
  damage from the ZnSMn.

71
Link to NASA Research Lunar Crater Observation
and Sensing Satellite (LCROSS)
Information from Dr. Jennifer L. Heldmann NASA
Ames Research Center T. Colaprete1, D. Wooden1,
E. Asphaug2, P. Schultz3, C.S. Plesko2, L. Ong2,
D. Korycansky2, K. Galal1, G. Briggs1 1 NASA
Ames Research Center, 2 UC Santa Cruz, 3 Brown
University
72
Basic Science Questions Addressed by LCROSS

• Nature and origin of polar hydrogen
• Distribution
• Concentration
• Origin
• Impact cratering dynamics
• - Plume evolution / ejecta curtain dynamics
• - Crater formation processes
• - Thermal evolution (plume, crater, remnant
  ejecta)
• 3) Target material properties
• - Geotechnical properties
• - Dust (particle size distribution, thermal
  properties, etc.)

73
Outstanding Science Questions
Lunar Prospector detected enhanced levels of
hydrogen near the lunar poles. What is the
Quantity, Form, and Distribution of the polar
hydrogen?? The answers are currently
unknown. Possible forms of the H 1) Water
ice? 2) Hydrated minerals? 3) Organics? 4) Solar
wind hydrogen?
Each implies different origin and emplacement
processes.
SP Hydrogen Abundance ( LP data)
74
Lunar Ice Summary
Not ICE Clementine bistatic radar
irreproducible results for ice, same signals seen
in sunlit areas. Arecibo not ice, same
signals seen in sunlit regions, not anomalous in
Shackleton. LP why more Hydrogen detected in
the north when more permanent shadow in the
south? Theory H2O evolution in lunar cold
trap reaches equilibrium over time (diffuse
deposits, 0.41 by mass).
ICE Clementine bistatic radar ice. Arecibo
ice. LP ice.
H measurements not definitive. Below 1-1.5 H,
form of H unknown.
75
Mission Description

• Lunar CRater Observing and
• Sensing Satellite (LCROSS)
• The LCROSS Mission is a Lunar Kinetic Impactor
  employed to reveal the presence nature of water
  on the Moon
• LCROSS Shepherding S/C (S-S/C) accurately directs
  the 2000 kg EDUS into a permanently shadowed
  region at a lunar pole, creating a substantial
  cloud of ejecta (60 km high, gt200x the energy of
  Lunar Prospector)
• The S-S/C decelerates, observes the EDUS plume,
  and then enters the plume using several
  instruments to look for water
• The S-S/C itself then becomes a 700 kg secondary
  impactor
• Lunar-orbital and Earth-based assets will also be
  able to study both plumes

Shepherding Spacecraft
1Launch Vehicle Earth Departure Upper Stage
76
Mission Timeline

• Lunar Gravity Assist, Lunar Return Orbit
  (LGALRO) Following the release of LRO, the S-S/C
  EDUS will enter a 86 day orbit (5 day lunar
  swing-by, 81 day earth orbit)
• Allows for LRO to become operational
• Allows for EDUS propellant boil-off
• Allows for impact targeting

• Upon separation from EDUS, about 8 hours before
  impact, the S-S/C will decelerate to trail the
  EDUS by 4 minutes and position itself to capture
  EDUS impact images and impact plume data

• During the 4 minutes after EDUS impact, the S-S/C
  will be collecting and transmitting data, then
  slightly divert its trajectory to impact the same
  general area at T4 minutes, but offset by
  several hundred meters.

Nominal launch date Oct 2008 Nominal impact
date mid-Feb 2009
77
Impact Observation Strategy

• Bright Impact Flash
• Thermal OH Production
• Rapid Thermal Evolution

• Expansion of Plume
• Thermal Evolution
• H2O ice sublimation
• Photo-production of OH

• Residual Thermal Blanket
• Expanding OH Exosphere

The combination of ground-based, orbital and
in-situ platforms span the necessary temporal and
spatial scales from sec/m to hours/km.
78
LCROSS S/S-C
Camera VIS context camera to 1) observe EDUS
impact, 2) observe ejecta cloud morphology and
evolution. Luminance Diode VIS observe impact
flash light flash due to thermal heating
vaporization shape of the flashs light
curve can be used to determine certain initial
conditions of the impact flash peak
intensity depends on impact velocity angle,
target projectile types
TL?
Ernst and Schultz 2003
Light curve as recorded from a photodiode of a
typical Pyrex impact into pumice dust at the NASA
Ames Vertical Gun Range. Two components can be
seen as intensity peak lasting 50-100 ?s that
depends on projectile parameters, and a
long-lasting decaying blackbody signal dependant
on target parameters.
79
For more information
Website lcross.arc.nasa.gov Contact
me Dr. Jennifer L. Heldmann LCROSS Observation
Campaign Coordinator NASA Ames Research
Center Mail Stop 245-3 Moffett Field, CA
94035 650-604-5540 jheldmann_at_mail.arc.nasa.gov
80
Conclusions
Photo taken on December 16, 1992 by the Galileo
spacecraft from a distance of about 6.2 million
kilometers (3.9 million miles) from the Moon in
orbit about the Earth.
81
Conclusions

• Measurements show that TL is generated during
  collisions with projectiles that have speeds of a
  few meters per second to nearly 6 km/s.
• TL can be detected by front facing sensors
• Other sources of light from the impact make this
  process much more difficult.
• Spectral measurements will be necessary to
  identify TL in the light signature.
• TL might be a part of the lunar LCROSS impact
  process.
• TL has the potential be used as the active
  element for a space-based impact sensor system.

82
Selected References

• S.W. Allison and G.T. Gillies, Remote Thermometry
  with Thermographic Phosphors Instrumentation and
  Applications, Rev. Sci. Instrum, 68 (7),
  2615-2650 (1997).
• N.P. Bergeron, S.M. Goedeke, W.A. Hollerman, C.I.
  Muntele, S.W. Allison, and D. Ila, Evidence of
  Annealed Proton Damage From a ZnSMn-Based
  Phosphor Paint, Space Technology and Applications
  International Forum (STAIF) Proceedings, American
  Institute of Physics, 746, 762-767 (2006).
• N.P. Bergeron, W.A. Hollerman, S.M. Goedeke, M.
  Hovater, W. Hubbs, A. Fichum, R.J. Moore, S.W.
  Allison, and D.L. Edwards, Experimental Evidence
  of Triboluminescence Induced by Hypervelocity
  Impact, International Journal of Impact
  Engineering, 33 (1-12), 91-99 (2006).
• N.P. Bergeron, W.A. Hollerman, S.M. Goedeke, and
  R.J. Moore, Triboluminescent Properties of Zinc
  Sulfide Phosphors Due to Hypervelocity Impact,
  International Journal of Impact Engineering, 2008
  (In Print).
• B.P. Chandra and J.I. Zink, Mechanical
  Characteristics and Mechanism of the
  Triboluminescence of Fluorescent Molecular
  Crystals, J. Chem. Phys., 73 (12), 5933-5941
  (1980).
• F. Freund, Charge Generation and Propagation in
  Igneous Rocks, Journal of Geodynamics, 33,
  543570 (2002).
• G.H. Heiken, D.T. Vaniman, and B.M. French,
  Editors, Lunar Sourcebook A Users Guide to the
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83
Selected References (cont)

• W.A. Hollerman, S.M. Goedeke, N.P. Bergeron, R.J.
  Moore, S.W. Allison, and L.A. Lewis, Emission
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  Photonics for Space Environments X, Society of
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  2005.
• W.A. Hollerman, S.M. Goedeke, N.P. Bergeron, C.I.
  Muntele, S.W. Allison, and D. Ila, Effects of
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  Such as ZnSMn, Nuclear Instruments and Methods
  in Physics Research, B241, 578-582 (2005).
• W.A. Hollerman, N.P. Bergeron, S.M. Goedeke, S.W.
  Allison, C.I. Muntele, D. Ila, and R.J. Moore,
  Annealing Effects of Triboluminescence Production
  on Irradiated ZnSMn, Proceedings of the 14th
  International Conference on Surface Modification
  of Materials by Ion Beam, Kusadasi, Turkey
  September 4-9, 2005.
• I. Sage and G. Bourhill, Triboluminescent
  Materials for Structural Damage Monitoring, J.
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• L. Sweeting, Triboluminescence With and Without
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• A. J. Walton, Triboluminescence, Adv. Physics, 26
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• F.N. Womack, N.P. Bergeron, S.M. Goedeke, W.A.
  Hollerman, and S.W. Allison, Measurement of
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84
Acknowledgements
Many people and organizations made this research
possible, namely
Dr. Dave Edwards and colleagues from MSFC for
their assistance with our research. Dr. Peter
Wasilewski for his assistance and the use of the
NASA GSFC one stage light gas gun. Dr.
Friedemann Freund from NASA Ames and the SETI
Institute for his assistance with the GSFC
gun. Drs. Richard Fahey and Joshua Halpern of
the GSFC Office of Higher Education for providing
financial assistance through the NASA ESMD team
program. Drs. Daryush Ila and Claudiu Muntele
for their assistance and use of the Pelletron
accelerator at AAMU. Other travel and related
funding was provided by the State of Louisiana
Board of Regents using the Space Grant
Program. Continued assistance of Oak Ridge
National Laboratory.