NASA TECHNICAL MEMORANDUM...NASA TECHNICAL MEMORANDUM PASSIVE OPT1 CAL SAMPLE ASSEMBLY (POSA): FINAL REPOkT By Roger C. Linton, Edgar R. Miller, and hlichael Susko Space Sciences Laboratory

N A S A TECHNICAL

MEMORANDUM

PASSIVE OPT1 CAL SAMPLE ASSEMBLY (POSA): F INAL REPOkT

By Roger C . Linton, Edgar R . Miller, and hlichael Susko Space Sciences Laboratory

August 198 1

NASA

George C. Mdrshafl Space Flight Center

Mdrsha l Space Fbgbt Center, A hzbdmd (NASA-Td-82446) PASSIVE C P T l C A L SAMPLE N82-12656 ASSEMBLY (POSA) F i n a l Report (NASA) 47 p HC AO3/HP A31 CSCL 138

Unclas 63/45 08417

https://ntrs.nasa.gov/search.jsp?R=19820004783 2020-05-30T02:08:27+00:00Z

T F C H N I C A L RhPORT S T A N D A R D TITLE P A G E 1. REPORT NO. 2. GWLI INWNT U C C S I I O N NO. 3. RCCIPIENT'S CATALOG NO.

NASA TM-82446 4. TITLE AND SUDTITLC 5. REPORT DATE

August 1981 Passive Optical Sample Assembly (POSA) : Final Report 6. PLRFORMING ~ G A N I Z A T I O N CCOE

J 7. AUfHOR(S) 8. PERFORMING ORGANIZATION REPOA r #

Roger C . Linton, Edgar R . Miller, and Michael Susko 9. PERFORMING ORGANIZATION NAMC AN0 AODREII to. WORK UNIT, NO.

George C . Marshall Space Flight Center Marshall Space Flight Center, Alabama 35812 I 1. CONTRACT OR GRANT NO.

r 19. t y p e o f REPOR',' & PERIOD CbVERED

12. SPONSMING AGENCY NAME AN0 ADDRESS

Technical Memorandum National Aeronautics and Space Administration Washington, D . C . 20546 1.1. SPONSORING AGENCY CODE

I

15. SUPPLEMENTARY NOTES I I I Prepared by Space Scieaces Laboratory, Science and Engineering Directorate 1

The Pazsive Opt ica l Sample Assembly (POSA) is a pass ive ly deployed a r r a y of contaminat ion-sensi t ive samples. A POSA u n i t was mounted and flown i n t h e cargo bay o f t h e Space S h u t t l e Columbia dur ing t h e f i r s t O r b i t a l F l igh t Test (OFT-1). A s i m i l a r u n i t was mounted i n a d i f f e r e n t l o c a t i o n i n t h e cargo bay a t Dryden F l igh t Research Center dur ing t h e p o s t f l i g h t opera t ions t h e r e p r i o r t o t h e f e r r y f l i g h t r e tu rn o f Columbia t o Kennedy Space Center.

The samples i n both POSA a r r a y s were subjected t o a s e r i e s o f o p t i c a l and a n a l y t i c a l measurements p r i o r t o d e l i v e r y f o r i n s t a l l a t i o n i n t h e cargo bay and a f t e r r e t r i e v a l of t h e f l i g h t hardware. This r e p o r t p resen t s t h e f i n a l r e s u l t s of a comparison o f t h e two s e r i e s o f measurements. These STS-1 r e s u l t s a r e based on d a t a obtained I'rom only a por t ion of one o f t h e t e n Induced Environment Contami- nat ion blonitor (IECM) instruments t o be flown on s e v e r a l S h u t t l e f l i g h t s beginning with STS-2. These l imi ted r e s u l t s do not i n d i c a t e S h u t t l e contamination l e v e l s i n excess o f those a n t i c i p a t e d . h c h more d e f i n i t i v e d a t a w i l l be ob ta inab le from planned f l i g h t s o f t h e f u l l IECh1.

17. KEV WORDS I@. D l s T R l e u T l o ~ STATEMENT

Contamination Passive optical experiment OFT - 1 experiment

I Unclassified - Unlimited

I

19. SECURITV CLASSI'. (d IN -)arr\ ;K). SECURITV CLASSIC. (d I l J m -80) 21. NO. OF PAGES I Unclassified I Unclassified I 46 I NTIS 1

U I C . t o m a l n l (La. Doa.ilrr I*?)) For rlr by N @ U d TIchrrM Ial-Uoa 9wvka. Bprlryllcld, VLnidr 3 a 1 I1

The authors appreciate the cooperation and technical assistance of the following MSFC personnel in this project: Larry W . Russell, ES 54, who served as Project Engineer ; Donald R . Wilkes , ES 64, who conducted tile diffuse reflectance measurement6 ; William K . Witherow, ES 74, who conducted the particle distribuion investigations ; and D r . John C. McClure, EH22, who conducted the Auger analysis. They thank Ray Black, ES64, for technical support ; James W . Berry, ES 54, for project logistics ; and John W . Redmon , EP 38, for design support.

TABLE OF CONTENTS

INTRODUCTION ............................................................. DESCRIPTION O F HARDWARE ............................................... POSA MISSION DETAILS .................................................... PHOTOGRAPHIC EVAI.UATION ............................................... RESULTS - O P T I C A L MEASUREMENTS ....................................... SUMMARY O F CONCLUSIONS - VACUUM ULTRAVIOLET OPTICAL RESULTS . RESULTS - PARTICLE ANALYSIS OF OPTICAL SAMPLES .................... RESULTS - ELECTRET ANALYSIS ........................................... RESULTS - ELEMENTAL ANALYSIS O F OPTICAL SAMPLES ................... GENERAL CONCLUSIONS ....................................................

................................................................ APPENDIX A

................................................................ REFERENCES

iii

LIST OF ILLUSTRATIONS

Figure

1.

2.

3.

4.

Title

Shuttle Orbiter configuration.. ................................... POSA /DFI postflight. ............................................ POSAIDFI: sample positions A and B (MgF2/A1, gold) ............

0

POSA IDFI : sample positions C , D (1810 A filter, CaF2). .......... POSAIDFI: sample positions E , F (CaF2 No. 2 , electrets), ....... POSAIFF ........................................................ POS i IFF : sample positions A, B (MgF2/Al, gold) ................

0 ...... . POSA IFF : sample positions C 1) (1790 A filter, fused silica )

............... POSAIFF: sample positions E , t.' (CaF2, electrets).

Phase-contrast microphotographs of "smudge" on san~ple A ........................................ (MgF2/Al) of POSA IDFI..

Phase-contrast microphotographs of droplet (Residue) on ............................... sample A (MgF2/A1) of POSAIDFI..

Enhanced magnification phase/contrast nlicrophotograph of ................... "smudge" on sample A (SlgF2/Al) of POSAIDFI.

..................... Optical results : sample MgF2/A1, position A.

........................ Optical results : gold sample, position B. .

........................... POSA IDFI simple MgF 2/Al, position A .

........................... POSAIFF san~plc MgFdAl, position A . .

I'OSA 1I)I:I sanlple MgF21Al, reverse side ( - Z) facing' ................................................ DFI pirllct s t r u t . .

................................ POSA 11) 1:I culd sirnlplc . position U

................................ YOS A I1:l: gold san~plc. position 13.

I'OSA /DI:I sc~n~pla : 1810 filtcr . position C . ...................... G ........................ 1'OSA ll:l: sc~n~plc: l i 9 0 I\ filtclg. p s i tion C

...................... 1'OSh 1l:l: ss~llple: 1 i9U .; filter. position C . .

Figure

24.

25.

26.

LIST OF ILLUSTRATIONS (Concluded)

Title Page

........................ POSAIDFI sample: CaF2 No. 2, position D 23

....................... POSAIFF sample: fused silica, position D.. 24

POSAIDFI sample: CaF2, reverse side ( -Z) , facing DFI ...................................................... pallet s t ru t . . 25

............................. POSAIDFI sample: CaF2, position E . . 26

............................... POSAIFF sample: CaF2, position E. 27

................ Particle size distributions on electrets on POSA IDFI 34

............... Particle size distributions on zlectrets on POSAIFF.. 35

Particle distributions on electrets of POSAIFF.. .................... 35

..................... Particle distributions on electrets of POSA IDFI 36

LIST OF TABLES

Table Title Page

Passive Optical Sample Assembly (POSA) . DFI Pallet Unit .......... 2

........ Passive Optical Sample Assembly (POSA) . Ferry Flight Unit 2

................................. Summary Of POSA Optical Results 13

......................... POSA - Particle Distribution Measurements 29

......................... POSA . Particle Distribution Measurements 29





Comparison Of Electret Results During STS-1 Orbital Flight And Ferry Flight .................................................. 33

Scanning Electron Microprobe Analysis Of POSA IDFI ...................................... MgF 2/Al Mirror Contaminants 37

NASA TECHNICAL MEMORANDUM

PASSIVE OPT1 CAL SAMPLE ASSEMBLY (POSA): FINAL REPORT

INTRODUCTION

An array of contamination-sensitive collector surfaces was mounted and flowrl in the cargo bay cf the Space Shuttle Columbia (STS-1) during the first Orbital Flig .t Test (OFT - 1) , April 12- 14, 1981. A similar array was mounted in a different location in the cargo bay at Dryden Flight Research Center during the postflight operat40ns there prior to the "ferry flight" of Columbia back to Kennedy Space Center (KSC) . Designated as the Passive Optical Sample Assembly (POSA) , the arrays were flown to rid in the assessment of contamination hazards of the Shuttle cargo bay for future missions.

POSA is a modified version of one of the instruments included in the Induced Environment Contamination Monitor (IECM) , an integrated technology payload consisting of 10 individual instruments sharing a common power and data collection system. The IECM, designated for flight an all Orbiter Flight Tests (OFT'S) succeeding the first and on Spacelabs 1 and 2 , is designed to provide verification measurements of Shuttle contam- ir,ant emission and deposit levels during g ~ o u n d operations, ascent, on-orbit , descent, and postlanding. The POSA, modeled after i ts parent IECM experiment (Passive Sample Array), was included on OFT- 1 to provide baseline contamination verification of the Shuttle environment for the design and user communities.

The POSA unit flown on the orbital phase of the mission was mounted on the Development Flight Instrumentation (DFI) pallet. It will henceforth be designated as the POSAIDFI unit. The POSA unit mounted for just the ferry flight will be designated as the POSAIFF. Samples in the POSA/CFI were subject to deposition of contaminants throughout prelaunch, ascent, orbital, descent, and ferry flight phases of the OFT - 1 mission. Inclusion of the second POSA unit, POSA IFF, during the ferry flight phase of the mission provided a means of identifying contamination hazards peculiar to that single phase of the mission.

Both 1'OSA units are totully passive in nature. Each is a mounted array of five optical samples and three static-charged Teflon sheets (electret;). Circumstances led to the inclusion of only two elecirets on the POSAIFF unit. Also, uv-grade fused silica was substitued for the CuF2 window (sample D) for POSAIFF.

Ttlbles 1 ilnd 2 provide directories of the sanlples contained in the POSA utlits. The basic .- composition and criteriu for selection of the samples flcwn are included in Appendix A . I

A l l of the sunlples were subjected to u series of optical and analytical measurements at - ; the Marshall Space Flight Center (MSFC) prior to delivery for installation at KSC and 7.

.~ F Dryden k'liglrt Reseusch Ccnter. The measurements were repeated in an identical manner t ~ t RIS1:C following rctrievul of the flight hurdwure .

TABLE 1. PASSIVE OPTICAL SAMPLE ASSEMBLY (POSA) ,

DFI PALLET UNIT

TABLE 2. PASSIVE OPTICAL SAMPLE ASSEMBLY (POSA) ,

FERRY FLIGHT UNIT

- 9

Tray 012

Sample

A

B

C

D

E

Material

Magnesium Fluoride Overcoated Aluminum (MgF2/A1)

Gold Mirror

1810 Filter

CaF2 Window (calcium fluoride)

Top : CaF2 Window

Base: Electret No. 9

Top: Electret No. 11

Base: Electret No. 10

- Tray 05

Simple

A

B

C

D

E

I:

,

Material

MgF /A1 Mirror

Cold hlirror

1790 1:ilter

U V - Grade Fused Silica

C;IF., Window

Top: Electret No. 1 4

liiisc: Electret No. 13

DESCRIPTION OF HARDWARE

Each POSA unit consists basically of a rectangular holder with six cylindrical receptacles (1.09 in. wide by 0.187 in. deep) bored at equal spacing. Smaller (0.75 in. diameter) holes in each of the sample "slots" are counterbored completely through tne holder so that effluents can reach front and rear surfaces of the samples.

A retainer plate with six circular "aperturest1 is bolted over the sample holder, allowing maximum front-surface exposure of the samples while holding down the outer edges. During those phases of ground handling, transportation, and installation when exposure was not desired, a solid, rectangular cover plate with captive screws was attached to protect the samples. The POSA hardware was machined from 300 series stainless steel. A more detailed description of the POSA hardware, including assembly and handling specifications, is available in a prior publication 111.

POSA MISSION DETAILS

The POSAIDFI unit was mounted to the starboard rail of the DFI pallet (Xo = i t

1069) in the Shuttle cargo bay. In Shuttle coordinates, the array was mounted in I i

the X , Y plane, with the samples1 surface normd parallel to the Shuttle Z-axis (Fig. 1) . \ i

AFT BULKHEAD

NOTE: ALL STATION NUMBERS (X,, Yo, 2,) IN INCHES.

DFI PALLE T RAIL

1:igwc 1 . Shuttle Orbitcr configurution.

The POSAIFF unit was separately mounted, postlanding at Edwards AFB, a t a cargo bay location specified by Xo = 750, inside access door No. 44.

A summary oi pertinent mission timeline details was provided in the "quick-lookt1 report [21. It 1s necessary to consider that the samples of the POSAIDFI unit were exposed, uncovered, in the cargo bay for nearly a month prior to launch. During this period, the cargo bay doors were closed with no access of personnel. With ref erence to both units, there were 9 days of exposure to the ambient c a r p bay en-' - ronment on the ground at Edwards AFB.

PHOTOGRAPHIC EVALUATION

The flight units were returned to MSFC on May 7 , 1981. They were photo- graphed, as received on May 8 (Figs. 2 through 9) in the envimnment of a class 10,000 laminar flow bench. The larger particulates (andlor fibers) can be readily observed in the photographs on the samples of both units; considerably greater amounts of particulates of smaller size can be seen on closer inspection under magnification (see Particulate Analysis, later in this report ). Visual inspection of the samples from i.oth POSA units reveals no direct evidence of a contaminant film, with the single exception of the magnesium fluoride overcoated aluminum (Mgk' /Al) mirror of 2 the POSAIDFI unit (Figs. 2 and 3). The smudge and the droplet on this sample were examined with the magnification of a phase-contrast microscope (Figs. 10 through 12). From examination of these photographs, the "dendriticl' pattern in the smudge lacks the regularity and pattern of t rue crystalline dendritic growth. Since the smudge and the droplet were later determined to have the same conpositio~i (see Chemical Analysis, later in this report ) , and the droplet has no such pattern , the conclusion of human involvement with, perhaps, a fine-haired brush is more likely as a source for the smudge pattern.

RESULTS - OPTICAL MEASUREMENTS

Optical n~easurernents of the POSA sanlples were performed on two sepilrcite instru- n~entution facilities. In the wi~trelength range 120 to 290 nnl , speculor . spectral reflec- tuncc i~nd t r i~~ l~ iu i t t i ~ncc (at ncnr-~lor~n~ill incidence) were measured :n a reflectometer at t lie cxit slit of i t Scyil- Ni~n~iokii- type n~onocli~vnli~tor . A hydroge dischilrge lamp w l ~ s utilizcil i~s the source. Thc ~~~ci~surernents were extended through 2.5 p n i wavelength (ovcrltipping slightly in tlie neilr uv) by meilsuring tllc diffuse reflectance and bocksci~ttcr coefficient in i t U~.cka~anl(;ier-Dunkle ilitcgrc~ting sphere facility, on two of the scln~plcs in ciich I'OSA unit.

'l'llc ~ ~ c s u l t s of' tlle dit'fusc I 'CIIL'C~~II~CC ~IIcasurcnIclits i\IX S ~ I O W I ~ in FigulSes 13 i111d 14. Ncit hcr of' thc I'OSA /I:I: S ~ I I I I ~ ) I ~ S n~cnsured ill tlic Gier-Dunkle facility (0. 25 to 2.5 ~ m ) indici~tc, iu iy i icg~*i~ti ;~tio~i tllrougll tlii~t SpcCtl'ill I'ilIifi'e. The gold mirror of IQSt\/DI:l indiciltctl soillc tlcg:.l.i~tliltio~i ( 1 2 pcrccnt) in the near-ultraviolet.

'I'lw sa~udgcd M g F 2 / ~ l mirror from the POSAIDFI unit indicated, by these diffuse -

I * C ~ ~ C C ~ ~ I I I C C I I I C ~ I S L I I * C I I I C I ~ ~ S . i1 10 p e ~ ~ c e ~ i t rcltitivc ~ I I C ~ C ~ I S C ill ~~~~~~~or obsorptm~ce. Back- sct~ttcr n~cttsulrnlclits ori ttus S ~ I I I ~ } B ~ C . ill tlus ri1IIgC. ind~cutcd un increase more than cloublc tlic o ~ ~ i g i ~ i i ~ l Lcvcl. irltlloirgl~ t11c levels (0.02 preflight , 0.07 postflight) a r e , in ~ntrkmitudc . subject to ItuKc \rtlccrtirint~.

"'I I F ; i.

ORIGINAL PA@ Is OF POOR Q U A m

Figure 2. POS A IDFI postflight

Figure 3. PnSAIDFI: sample positions A and B (MgF21A1. p l d ) .

5

0

Hgun 4. POSAIDFI : sample positions C . D (1810 A filter. CaFZ)

Figure 5. PoSAlDFI: vmple poaitims E . F (CaF2 N o . 2 . electm~&.

ORIGINAL PAW '3 OF POOR QUA r CY

Figure 6. POSAIFF. 1

0

Figul.c 8. POSAIFF: sample positions C , D (1790 A filter, fused silica).

Figure 9. FOSAIFF: sample positions E . F (CaF2, electrets).

I--- CENTER OF - W E " ----I

Figure 10. Phase-contrast microphotographs of "smudge" on sample A (MgF2 IAl) of POSA IDFI.

VIEW OF DROPLET

Figure 11 . P huse - contrast rnicrophotopaphs of drop let (residue) on sample A (MgF2!AI) of POSAIDFI.

Figure 12. Enhnnced nia~g~~ificntio~~ phase lcont rnst microp llotograph of "smudge" on st~nlplc A (RlgF,/AI) o f 1 V S A 11)l'I .

"

The results of the vtlcuunl ultrnviolet n~e~suren~crlts of specular, spectral refAec- tunce and transmittc~ncc rrrc sllown in 1:i~urcs 15 through 5 8 . A t~bulated summary of these results is listcd in 'Strblc 3. Yur cnch Opticall s:~rllplc of ench POSA unit , the curvcs show the postflight chanp?s in Iht? nlc~rsurctl opticnl properties. and additionally, on scpurate grtrphs. show thc computcti pcrccnt chrlnges for ~sscss ing the significance of indicr~ted degrr~dution. The rcflccturlcc . tr!~d pcrccnt chtlnges in reflectance, of the narrow band ultraviolet filters (Snmples C of both POSA units) were included dmply to extend the spectral range of investigt~tion (E'igs. 2 1 mid 23).

From these dr~tn some genera11 co~~clusions cnti bc rctrdily inferred:

The reflectunce and the percent chr~ngv in reflwtl~ncc of the MgF2/Al mirror of

POS A /DFI indictite a unifornm 10 percer~t rclrttivc dccrcnsc flwm preflight levels, in gcneral agreement with the diffuse r e f l ~ ~ t n n c e rcsults. For t l ~ c ferry flight MgFZIAl

mirror. the indicnted dcgrrlclntion is less over most of t hc wrrvclcngth range, with evi- der~cc of some spccr 1.111 effects (P ig . 16). Ttlc t~bsencc of spcctrnl effects in the POSAl DFI MgF2/AI mirror mny be r~ttributed to light scattering fmnl t l r smudge and droplet.

- masking any intcrferencu? effects thtlt lllrly be prcscnt. A sihmificrlnt increase in back- scr~tter on the smudgvd mirror w c ~ s rictccteci by the Gicr I)urlklc/Ucckrnan facility at longcr w~velengt hs,

- INITIAL

------ FINAL

WAVELENGTH MICRONS

a. POSAIDFI sample.

o+ o f I 1 .o 1

1.5 210 2 5 WAVELENGTH YKROW

1:igul-c 13. Opticiil ~vsults: suniple RlgY /A1 , position A . 2

-- INITIAL ----- FINAL

-1--- -7-- 1 1 - 1 0 5 10 1 5 2 0 2 5

WAVELCNGTM MICRONS

:.i. POSA /DFI suniyle.

- INITIAL

- - - - FINAL

I:igut-c 14. Oplic'irl ~ r s u l t s : guld son~y lc , posit ion U .

TABLE 3. SUMMARY OF POSA OPTICAL RESULTS. t

POSAIDFI POSAJFF

SAMPLE %A - %A - MgFZIAl Reflectance: - 10% Reflectance : - 10%

Gold Reflectance : - 16% Reflectance: -15%

UV Filter Transmittance : 510% Transmittance : - 10% to +14% Reflectance : - 25% to + 9 m e f l e c t a n c e : -21% to +8%

1810 1 Filter 1790 Filter

"Windowt' Transmittance : - +2 % Transmittance : 22% (SiO 2) Position D (CaF2)

"Windowt' Transmittance: -8% to +6% Transmittance: -5% to +2% Position E (CaF2) (Cap2)

%A = Maximum percent change in reflectance in range 120 - 2500 nm.

For the reverse side of the MgF2/A1 mirror of POSAIDFI (Fig. 17), the data n

indicate significant changes below 1700 A (% 10 percent) , with no apparent degradation at higher wavelengths. The comparable results for the MgF2/Al mirror of POSAI

FF indicate no apparent change throughout the measured spectral range. The most likely source of contamination for the reverse sidc of these samples i s the paint-coated surface of the DFI pallet s t ru t to which the POSA was mounted (offset). This paint was Chem-Glaze A8-276, an acrylic polyurethane coating with titanium oxide (Ti02).

Results of the gold mirror; of both POSA units (Figs. 18 and 19) indicate simi- lor change (approximately 10 percent decrease in reflectance, relative), with the range of uncertainty masking any possible significant differences. There i s , again considering the uncertainty, little significant change at wavelengths greater than 2400 Angstroms, confirming the results of the diffuse data from the Beckman DK-2 facility.

The results for the vacuum ultraviolet filters (2.200 1 bandwidth) indicate no significunt change in the transmittance for the filter of either POSA unit, considering the uncertainty (1:igs. 20 and 22) . The front surface reflectance of these filters indicutcs nieasurellble dcgriidiition, illthough the greater change occurred in the region of lower front-surface reflcctiitlcc (triinsnlissive biindwidth) and is subject to greater uncertuinty due to the lower initial magnitude of reflectance.

'L'here is genertilly no sig~lificant chiinge in the optical properties of any of the tll:rnsplrrent siin~ples (CirY., . fused silicir) of either POSA unit, with the exception of - the rellectirncc of the rcversc side of the CuF2 sanlple in position D of POSAIDFI ;

t i ~e r e rvtrs no trppirretlt c11~ttlge in the reverse - side reflectance of the conlparable Sam - pic in IQSt\/F1'.

PA€-FLIGHT , 0 POST-FLIGHT j

Ro. PRE-FLIGHT REFLECTANCE R = POST-FLIGHT REFLECTANCE

80-

L

3 "- t Z: 5 40- a

20-

WAVELENGTH (A) X 1000

I I 1 I I

1:igure 15. l'OS.S/L)1:l sumplc M g F Z / A I , position A .

1.2 1.6 2.0 2.4 2.8 WAVELENGTH (A) X 1000

a. Reflectance measurements.



- x x x x n X x

- 10

APPROX. RANGE OF UNCERTAINTY -20


b. Cd~lculatcd pcrccnt chitngt in refi.:-:tame.

b'i~fut*c 16. 1'OSAII:I: sc~n!plc MgF /A l , position A. 2

WAVELENGTH (A) X 100CI



b. Citlculatcul pcrwnt chunp in l-eflcctunce.

W

-10 2 0 y -20- Y w 0 Z

E'igurc 18. POSAl1)FI kmld scln~yle, position B .

X x X X * - x x X x X

x

APPROX. RANGE OF UNCERTAIN1 Y

I I 1 1 1.2 1.6 2.0 2.4 2.8


7 X I I a

a ,, ' R C

APPROX. RWCE OF UNCERTAINTY Y

I:igum 19. I'OSA /I3&: h ~ l d s;alplc . position 8 .

1.2 1.6 2.0 2.4 2.8

WAVELENGTH (At X 1000

a. Transmittance measurements.

'AWROX. RANGE OF UNCERTAINTY

w*vELEmvn [A) x IOOO

b. Ci~iculutd pcrcent chtrnge in trm~n~ittunce. 0

Yigurc 20. I'OSA/L)FI sanrple: 1010 A filter, position C .

1.2 2.0 2.4

WAVELENQT M (A) X 1000


WAVELCNGTM 1Al X 1-

b. Ciilculirtcd ycrcctlt clrclngc irr rcflcctturcc. 0

i u c 1 . 1WSAIL)L:I sue~ylc: 1810 A filter, position C .



W

W

APPROX. RANGE OF UNCERTAINTY L.

WAVELENGTH (A1 X 1000

0

1:igurc 22. I'OSA/l:Y sdrnrplc: 1790 A filter, position C.

PRE-FLIGHT 0 W T - FLIGHT

1.6 2.0 2.4 WAVELENGTH (A) X 1000


w 1 !/ APPROX RANGE OF UNCERTAINTY ,., *10

I:igure 23. IIOSAIYI: aam~ylc: I tM filter, position C .

10-

i -- c. I -- 1)-

11 1 1 .e I I

2 0 I

2.4 2.a WAVELENGTH (A) X 1000

a. Trunsmittunce measurements.

TO - PRE-FLIGHT TRANS. T - POST-FLIGHT TRANS.

) . . x x x 1

- 10 APPROX RANGE OF UNCERTAINTY

WAVELENGTH (Al X 1000

Figure 24. POSAJDFI sample: CaFZ No. 2, position D.

I:igurc 25. lBOS:\ /1:1: srul~plc: fused silia~ , position D.

0 -

i .- [.-

20-

> I I I I I

1.2 1 .0 2.0 2.4 2-8 WAVELENGTH (A) X 1000


PRE-FLIGHT O POSl-FLIGHT

I I I 1.6 2.0 2.4



C U

-20 \APPROX. RANGE O f UNCERTAINTY

WAVELENGTH IAI X 1000

b. Cc~icul~~icd pcrccrit chir~igc in t runsalitt unce.

Figure 1'7. POSA/l)l:I sr~nlplc: Cur., , position B . "

POWFF U Y L E : CALCIUM FLUORIDE EI

?RE-FLIGHT o W)BT-FLIGHT

12 1.6 2.0 2.4

WAVELENGTH (AJ X 1000


POSAIFF SAMPLE CAF2 (WS. El

WAVELENGTH IAJ X 1000

1:igure 28. I'OSA/I:F silnlple: CaFy position E .

SUMMARY OF CONCLUSIONS - VACUUM ULTRAVIOLET OPTICAL RESULTS

Measurable degradation in the optical properties of the reflecting samples was 1 detected for both POSA units.

No measurable degradation was detected for the transmissive samples.

-.i Generally, the change in reflectance was slightly greater for samples of the POSAIDFI than for samples restricted to the ferry flight.

There was evidence of measurable degradation due to outgassing of the paint on the DFI pallet s t ru t .

RESULTS - PARTICLE ANALYSIS OF OPTICAL SAMPLES

The quantity and size distribution of particles on some of the samples of both POSA units have been measured using a white light, imaging, particle counting facility. These data include comparison scans of similar samples from the POSAIDFI unit and the POSAIFF unit. For all the samples, the results uniformly indicate a size distribution heavily weighted toward particles less than 10 pm in diameter, with the greater number of these less than 5 p m in diameter. The results indicate fur ther , that the type of sample surface may have a considerable influence on the number of adhering

5 2 particles; particle counts on the ultraviolet filters of both POSA units exceed 10 Icm for particle diameters lsss than 5 pni, while the comparable statistics for the other

3 samples wero lower by a factor of 10 . Preflight particle scans indicated an average count of 90 particles/cm2 on the

samples, with diameters < 10 prn. An updated summary of the results of the particle distribution measuremerlts, restricted for particles of diameter less than 10 pm, is shown in Table 4. With reference to the earlier quick-look report [ 2 ] , the differences in these results are attributed to the greater accuracy of count achieved by scanning larger areas of each sample in repeat n~easurements. These results confirm that , while d l samples of both POSA units collected nleasurnble levels of particles, nearly all of thc samples of POSAIDFI were denser in purticle distributions. The more detailed results, providing relative populiltion densities for particle size ranges up to 1000 pm in diunietcr, irre given in Tilbles 5 through 9. These results indicate no significant variations in the relative population distributions for samples of either POSA unit.

The lerge difference in particle pop uliltions O i the ultraviolet filters when corn- pnred to othcr 1'OSA suniplcs ~*eniiri~is puzzling, ulthough all of the results show some virricltions in irdlicrence depcndcnt on t lie siiniple type. The results did not change when pirrticle distribution nicirsurenients were repeated on i111 sitniples. Residual charge on 1111 of the POSA sclaiples (iulcl POSA control silniplcs) \Vils measured hlith o Iieithley Rlodel 6103 clcctrolllctcr to scc i f t lus could account for the greater apparent particle "sticking" of tlic ultri~violet filters; tllc results indicated i~ surface charge of a b u t

2 +lo- lo Coulualslc~il 011 the filters i111d tllc trirnspirrent POSh samples, with no c h a ~ g e

1. 13rr~sclr tltid I,otnb O I ~ ~ I ~ ~ C W ~ I ;\utoliri~lic Systcni , E S i 4 . MSFC.

TABLE 4. POSA - PARTICLE DISTRIBUTION MEASUREMENTS.

PARTICLE SIZE < 10 p m -

SAMPLE POSAIDFI COUNT POSAIFF COUNT

1866 Icm 2 1263lcm 2 A - MgF2/A1

1075/cm2 761 Icm 2

B - Cold

C - UV filter 5 2 1 .4 X 10 Icm


POSAIDFI POSAIFF MgF2/Al, Position A MgF2/Al, Position A

2 2 Total Area Scanned : 0.90 cm Total Area Scanned : 2.83 cm

Size Size Distribution Distribution

( v m ) Particles I Relative ( ~ m ) Particles1 Relative Diameter (em2) Population Diameter (em2) Population

0 - 2 259 . ***** 0 - 2 2 - 1 649 . ************ 2 - 4 4 - 6 416 . ******** 4 - 6 6 - 8 223 . **** 6 - 8 8 - 10 132 . ** 8 - 10 10 -. 12 87 . * 10 - 12 12 - 14 3 8 12 - 14 14 - 16 7 5 . * 14 - 16 16 - 18 2 3 16 - 18 18 - 20 20 18 - 20 20 - 22 22 20 - 22 22 24 10 "9 - - - 24 24 - 26 25 24 - 26 26 - 28 t 26 - 28 28 - 30 1 58 - 30 30 - 32 17 33 - 32 32 - 34 6 32 - 34 34 - 36 5 3 1 - 36 36 - 38 G 36 - 38 38 - 40 5 38 - 40 40 - 50 10 40 - 50 50 - 100 15 50 - 100 100 - 500 2 100 - 500 500 - 1000 t 500 - 1000

t fnvrl id readings result ing from instrument e m r


WSA IDFI Gold, Position 8

Total Area Scanned : 2.83 cm 2

Size Distribution

(urn) Diameter

Relative Population

POSA IFF Gold. Position B

Total Area Scanned : 2.83 cm 2

Size Distribution

(urn) Diemeter

Relative Population


POSAIDFI POSAIFF 1810 Filter. Position C 1790 A Filter. Position C

Total Area Scanned : 0.036 cm Total Area Scanned : 1.35 cm

Size Distribution

( ;m) Diarnctcr

0 I 1 2 1 :I 3 4 4 5 5 li l i i i H H 9 I 10 1 1 ) 1 1 1 1 I1 12 . 13 I : I I 4 I 4 15 I5 I G : t i 1 ; 17 19 i n 1 9 19 20 I 30 30 40 40 50 511 1011 1l111 500 3111 I UUO

Relative Population

. ***

. ***I****

. ********

. + r * * c *

. .*** **

. * *

. .

Size Distribution

( b m ) Diclrneter

Hclutive Population

tln\.rl i J r r ~ J ~ n p r c ~ c ~ l t in$ from inst rumnt error 30

TABLE 8. POSA - PARTICLE DISTRIBUTION MEASUREMENTS POSAlDFI FOSAlFF

Calciw Fluoride, Podtion D F w d Siltcr, Poritkn D Total Are8 Scmned: 2 . 8 3 cm Total Area Scanned : 2 . 8 3 cm

S i n Sire Distribution Dirt ribution

( ~ m ) Particles/ Relative (urn) Part icler / Relative Diameter (cm2) Population Diameter (cm2) Population

0 - 2 195 . +++ 0 - 2 183 . ++*I++ 2 - 4 445 . +++s++s 2 - 4 31 1 . +**+.**L+,

4 - 6 333 . **ss+ 4 - 6 160 . ++++* 6 - 8 266 .+a+* 6 - 8 175 . L++*+* 8 - 10 322 . **I,* 8 - 10 77 . C+

13 - 12 229 . +++ 10 - 12 45 . . 12 - 14 125 . *S 12 - 1 4 60 . +e 14 - 16 119 . ., 14 - 16 41 . 16 - 18 60 . 16 - 1 8 10 18 - 20 7 8 . 18 - 20 2 5 20 - 22 32 20 - 22 15 22 - 24 33 22 - 24 7 24 - 26 16 24 - 26 10 26 - 28 24 26 - 28 2 28 - 30 12 28 - 30 1 30 - 32 16 30 - 32 5 32 - 34 7 32 - 34 6 34 - 36 8 34 - 36 3 36 - 38 4 36 - 38 0 38 - 40 0 38 - 40 1 40 - 100 44 40 - 100 I 5 100 - 500 8 100 - 500 4

TABLE 9. POSA - PARTICLE DISTBIBUTION MEASUREMENTS. WSAIDFI WSAIFF

Calcium Fluoride, Position E Calciwn Fluoride, Poaition E Total Area Scanned : 2.90 cm Total Area Scanned : 2 . 6 6 cm

Size L)istribution

( u m ) Diumetcr

0 - 2 2 - 4 4 - 6 6 8 8 - 13 10 - 12 12 . 14 14 16 16 18 18 20 20 - 21 22 24 24 - 26 26 28 28 30 30 32 32 34 34 36 36 . 3U 38 40 40 50 50 IW I00 Sno 500 low

Relative Population

Size Distribution

(urn) Diameter

0 - 2 2 - 4 4 - 6 6 - 8 8 - 10 10 - 12 12 - 14 14 - 16 16 18 18 20 20 - 22 22 24 24 26 26 - 28 28 - 30 30 - 32 32 - 34 34 . 36 36 - 38 38 40 40 50 50 LOO 100 500 540 - I000

Part ides/ (cm2)

Relative Population

detected on the gold or IgF2/Al samples 131. Similar measurements indicated similar results on POSA control samples; since 10-lo Coulombs is about the limit of measurement for this particular electrometer, and the results indicate no unique charging ~ . f

3 the uv filters, the greater particle counts on the filters appear to have no relation to unique surface charging. No explanation is available for the anomalous low particle count on the CaF2 sample of POSAIFF either; repeated measurements confirmed the results given.

r

RESULTS - ELECTRET ANALYSIS

The electrets are made of Teflon-Polytetrafluorethylene , (C 2Fq)n. Electrets are

- 8 2 dielectrics with a permanent surface charge (approximately 10 Coulombs/cm density) that gives them properties analougous to magnets by retaining electrically active particles and ions on their surface [4]. Measurements are made in the energy range from 0.707 to 30 keV t 0.170 keV ( i . c . , fluorine to silver) using an X-ray lnicroprobe to ancllyze the effluents collected on the Teflon electrets. Thus , an elemental analysis and an estimate of the abundance of the elements are obtained. The area scanned

measured approximately 0.1 cln 2 , selected arbitrarily by the microprobe operator for o representative area of particle density. The r e s u l ~ ~ show the elemental abundance of an aggregate of particles on the electret surface.

Three electrets were included in the POSAIDFI for STS- 1. One was placed under Sample E , the calcium fluoride 'fwindow." For this electret, the surface normal was oriented 180 degrees ( -2 ) from the front surface normal of the CaF2 sample

for a measure of the directionality of effluent flow. The other two electrets were placed in sample slot 'IF'' of the POSA holder (one facing "up", +Z, the other facing "down", -2) for directionality analysis. In all cases, the positively polarized surface wcls the surface exposed.

Two electrets in the POSA/DI:I, position E (-Z) and electret No. 10, position F, (-2) , showed no evidence of contamination present. Electret No. 11, also at position 1: but filcing "+ZW, slowed a nleasurement of Si and A1 nfter X-ray nlicroprobe analysis. On the ferry flilzht of Columbin from Edwards AFB. California, to Kennedy Space Center, Floridir. no sipnificnllt ilnlount of Si was collected on the POSAIFF electrets, but an incrcclsc of A1 was measured on electrets 13 nnd 14 after the energy-dispersive analysis of the clcctrcts. In Table 10 tlie relative abundance of the elements was obtained by dividing thc observed vrllue by the preflight nlensurer:~,.~ts

Thc ~lui~tltity i~ntl size distribution of pilrticles on the orbitnl and ferry flight clcctrcts trre prcscnted in Figurcs 29 t l~rough 32. A s shown in the figures, the results indictltcd it sizc distributior, wci(1;htctl towilrd pilrticlcs less t l ~ m 20 Dm in both the orbitill cuid ferry nlissioli. t\ conlpilt+isoll of tlie plots shows iI treater number of particles obtcrinccl durinlr: thc ol*I>itill lllissioli tl~nll thc fcrry flight. Tllese particle sizes were mcl~surc<l by ;I Iii~uscll i111d I,on~b ..\l~to~lli~tic Systcm, a Iiigll-resolution particle sizing

9 systcrll. 2 At 1 0 ~ m;1gliificiltiol1 . t IIC i1lecir ~ i l n n c d \Viis 1 .27 em', hlorphology studies witlr it sc i r~i l~i t~g clcctron microscol>c (SEN) i~itlici~tcd irrcgulnrly shaped particles. ppncrr~lly Icss tllirn 2'0 .. 111 tliiimctor .

I 2 . Tlw? scrw systclrl (13Sf4, 31SI:C) used for pirrticlc cwutitirrg on the POSA optical

I samples.

0 0 ~ 0 0 0 300eV0 d m a n -

&?

ELECTRET # 0 (DOWN, -2)

ELECTRET # 10 (DOWN, -Z)

DISTRIBUTION

ELECTRET .o 11 (UP, +Z)

DISTRIBUTION

1:iyurc 29. Ptrrticlc s i x distributions on clcctl*ets on POSAIDFI.

ELECTRET X 13 (DOWN, -2)

DISTRIBUTION O - 10 (pm) 235

10 - 20 250 20 - 30 11 1 30 - 40 58 40 - 50 23 50 - 60 15 60 - 70 6 7r - 80 7 80 - 90 3 9 0 - 100 6

100 - 500 11 500 - loo0 1

ELECTRET # 14 (UP, +Z)

DISTRIBUTION

Figure 30. Particle size distributions on electrets on POSA IFF.

ELECTRET t 13 (DOWN, -ZI- ELECTRET = 10 (UP. +Z) ,,,,,,.,..

PART. - .. 0 10 20 30 40 50 60 70 80 90 100 ~1~

PARTICLE SIZE . r m

I:igurc 31. I'i~rticle clistributiotls on electrets of POSAJFF.

ELECTRET # 9 (DOWN, -2) - ELECTRET # 10 (DOWN, -21 .,..... ELECTRET it 11 (UP. +Z) ,----

PARTICLE SIZE

Figure 32. Ptirticle distributions on electrets of POSAIDFI.

HE:SUI,TS - ELERIEN'rAL ANALYSlS O F OI'TICAL SAMPLES

Sctrnriin(); electron aiicroscope itivestigutio~is of the pcirticles on tlie POSA samples reveciled nleasurnble le\?els of silicorl and itlunii~iuni; otliex* constituent elerne~lts were detected at levels bclorv statistical sig~lificu~ice . T hese results are i~iconclusive evi- derlce of the cheniicill ~itlture of the pilrticles because the SElLl probably detected base rllirror constituents 11s well.

The sniudgcd hlgl:2/Al silriiplc of POSA/L)121 w u s zubjected to Augcr u~iulysis. 011

the non -snludged lireti of the sciniplc, silicon wi is detected ill quantities sufficient to suggest the cxisterice of ti very tliin silicorie contilii~i~ia~it luyer. Within the areas of thc droplet und the sri~udge, 110 trtlcc of silicon wi ts detected. Instetid, signfieant levels of potcissiunl . clilol-ine, sodiuni , and riitroge~i , with trace quantities of sulpllur wcrc dctcctctl. 'l'he sliludgeci clrciis conti~ilicd tlie scinlr cheniiccil corlstituellts a s the droplet , t houg'li i l l ~ l i c i l ~ ~ r ~ i i b l y less qu;r~i t i t s .

Tlicsc typcs of Auger invest igiitio~is on co:.tnnii~iutcii saniplcs ge~icrclly indicate n residue of c l~lo~~i l lc irnd sulfur fro111 krl'ciiscs. bnsed on past esperierice. Potassiunl is not conlllionly Ibulitl; for this cnsc. it Dliiy bc Iiclpfui to l'eci111 tl1:lt potnssiunl clilorine is usuiilly Sou~iil in l~uniiui s\vc;rt. Nitro~eti ill tlic sn1udt~;c illid droplet is of unknown origin; it is soli~cti~iics dctcctcil ;is ; I tl'iicc c~~ltiitliitiiint frorll Ileiit~ti llet~lls

'l'lic sniuiigcd l'OS:\ 1:)l'l sirrlil)lc w, i s subsccluc~itly subjected to n s c n ~ l ~ ~ i ~ l ! ; electron ~ ~ ~ i c r o p r o l ~ c i ~ ~ ~ i r l y s i s . 'I'irblc 1 1 . s i i ~ i ~ ~ i i ; r ~ * i j r ~ s t l i ~ ~ ~ c s u l t s . S I I O \ V I ~ I ~ tlie ~ ' ~ l i l t i ~ c abundance of clcnients ilctcctctl it1 botli tiit! sliiutlgc i ~ l l t l tllc tlroplct. \Jliile tlic snludged nrca of the strn~plc ( 5000 .. 111 tliiirirclcl.) i s ~i~uc:li liir~~;i\~' f I i a i t l i ~ iIr'op1ct ( 1.111 dinnieter 1 , the only clc~licrits iictcctcil iri tlrc s~ i~~r t lgc wcrc n l i r g~ i c~ i~ i l~ . silico~i, nlic1 nluiainurii. These pci~ks u~itloul~tctlly rirow I'l.um tlic 11111~1~01~ itsclf. ;is i~idc~~er idcnt i~ives t i~nt ions 011 control 111irrol.s i ~ t t ~ l s t . 'I'11c 1*~1~11i\~e i ~ b l i ~ ~ ( l i i ~ l ~ ~ of c l~c~ i~ i c i~ l c o ~ i ~ t i t u e n t ~ ill t l l ~ droplets with I 'CI 'C~CIIC~ to t llc S I I I U ~ I K C . i l l t lie I ~ ~ ~ C I * O ~ I I ~ O I ~ C n ~ l ; r l v s i s . is Clue to tllc gretrtel* density of c~llli1lliilli1ll~ \flsil)l) ' i l ~ ) ~ ) i l l * C l l ~ I l l 1 1 1 ~ i l 1 ' ~ 1 > l ~ l .

TABLE 11. SCANNING ELECTRr'' MICROPROBE ANALYSIS OF POSAIDFI PgF2/A1 MI. . 3 R CONTAMINANTS

ELEMENT PROPORTIONAL COUNTS

Chlorine 4 50

Sodium 3 0

Phosphorous (or Zinc) 64

Sulphur 90

Potassium 650

Calcium 120

Independent investigations directed by Johnson Space Center (JSC) [3] of contamination in t t c Shuttle cargo bay provide some results correlative with the POSA material studies. These JSC results were obtained by analyzing the residue of a number of coliectirlg "wipes" from the Shuttle fore und aft radiators, indicating non-

particulate surface contaminant layers varying from to grams/cm2. T h e equivalent thickness of the contulninarlt layers leading to such densities can be est i-

0 mated as about one monoluyer (20-30 Angstroms), n result not irlcompatible with the optical and mnteriul properties results for POSA.

The volatility of the smudged contaminant i s very low; repeated exposure to

vacuum levels of 1 0 ' ~ torr to 10- tor r , fro111 the vncuua ultraviolet and the material [>roperties tes ts led to no discernible change in the quantity or npyearnnce of the smurlgc or the droplet.

In suatlIlilry. with respect to the sniudge nnd the droplet:

the coniposition is ccrtrlirlly not i . ~ silicone

thcrc w i t s probirbly so~iic Iluni;i~l-i~ssocinted intcrnction leading to the smudge

a it is lrkcly t r g~*cttsc, with otllcr co~ltnali~lnnts prcsent .

GENERAL CONCLUSIONS

At wavelengths greater than 3000 a, thCA.e is no significant optical change on samples of either POSA unit, except for the smudged mirror.

The most probable cause of most of the observed uv optical degradation is particulate deposition since it is measured on both POSA units and the evolution of the volatile species leading to molecular film contamination would not be expected in the ferry flight environment. Although there are indications of spectral effects, usually associated with the molecular contaminant films, in the reflectance data for the mirrors and the ultraviolet filters, the associated measurement uncertainty is large and the magnitude of reflectance change is relatively low.

A significant degradation at wavelengths lower than 1700 & was measured on the Sackside of DFI samples with a large view factor to the painted DFI structure.

There was evidence of a very thin silicone contaminant layer on the POSAIDFI samples from Auger analysis.

The smudge on the one DFI sample was not a silicone; it is probably a hydro- carbon grease.

The particulate levels were very high in the range of diameters < 5 Dm for mirror samples of both POSA w i t s and less on the transparent samples of both units, indicating significant variations in adherence.

It is emphasized that these results are for unprotected samples subjected to all phases of the flight, including the ferry flight. The STS-1 was subjected for many months to a relatively uncontrolled environment during manufacturing efforts. These results permit a first estimation of the anticipated degradation for unprotected (exposed) optics in the Shuttle cargo bay: it is expected that future Shuttle n~issions will be conducted with less environmental exposure in the prelaunch phases. These STS-1 results are, of course, based on data obtained from only a portion of one of the ten IECM instruments to be flown on several Shuttle flights beginning with STS-2. These limited results, however, do not indicate Shuttle contamination levels in excess of those which \irere anticipated. Much more definitive data will be obtained from thc planned flights of the full IECh1.

APPENDIX A

The basic philosophy of sample selection was determined by the relative contamination sensitivity and the relevance of concern for similar materials as components of future ST S payloads :

A. MgF2/Al: An optically flat ( h i l o ) fuxed silica substrate is coated with 100 0 A thickness of luminum which i s , in tu rn , overcoated with a protective and reflective- W enhancing 250 thick layer of magnesium fluoride. The substrate thickness i s 32 mm (0.125 ir.. ). This particular composition of thin film mirror provides the highest reflectance in the vacuum ultraviolet spectral range through, or down to, 1216 [h wavelength (Lyman a). Telescope mirrors and diffraction gratings are frequently of the same composition.

B . Au: The gold mirror consists of a 400 %I thickness layer of 0.9995 pure gold on a fused silica substrate. The substrates of all mirrors selected for use in the POSA are identical. Both gold and MgF2/A1 mirrors are standard components of space optical

instrumentation. Gold is particularly useful as a coating for uv optical elements for i ts reasonable magnitude of reflectance and its well-known insensitivity to oxidation or tar- nishing.

C . Filters: The vacuum ultraviolet filters are composed of a multilayer thin film composition deposited on ~nagnesiun~ fluoride substrates. The filters transmit a

0

225 A bandwidth of light centered at the designated peak wavelength. Interference filters are common components of vacuum ultraviolet instruments flown in space. The transmission is highly sensitive to contamination. The filters are opaque to all wavelengths of light in the range of 0.12 to 2.5 p except, of course, for the "narrow" bandwidth, as designated.

D. CaF2: The calcium fluoride "window" is dimensionally identical to the mirror

substrates ; both sides are optically polished. Transmission extends through the ultraviolet. Because of hardness, resistance to water, uv-induced damage, and favorable transmission properties in the vacuum ultraviolet, calcium fluoride instrumentation (particularly as windows for environmentally sensitive detectors).

E . SO2: The fused silica window, optically polished on both sides (X/4), mea-

sures 2.54 cm diameter, 2.5 ninl thick. With the onset of transmission above 160 nano- meters, this material is i l conlmon "window" for detectors having medium spectral vacuum ultri~violet sensitivity. It is also a con~man substrate for optical mirrors.

1. Linton, Roger C. : The Passive Optical Sample Assembly (POSA) on STS-1. NASA TM-82407, March 1981.

2. Linton, Roger C . and Miller, Edgar R . : Passive Optical Sample Assembly (POSA) ior STS - 1 - - Quick-Look Postmission Report, NASA TM- 82421, June 1981.

3. Personal communication with Dr. Lubert Leger , ES5, Johnson Space Center.

4. Piilai , P. K. C. and Shriver , Edward L. : Electrets and Their Applications in Contanlintition Studies. NASA Technical Report R- 457, 1975.

APPROVAL

PASSIVE OPTICAL SAMPLE ASSEMBLY (POSA): F INAL REPORT

By Roger C . Linton, Edgar R . Miller, and Michael Susko

The information in this report has been reviewed for technical content. Review of any information concerning Department of Defense or nuclear energy activities or programs has been made by the MSFC Security Classification Officer. This report, in its entirety, has been determined to be unclassified.

L* j t f ~ . ~ : . KINCSBURY / ' ~ c t i n g Director. Space Sciences Laboratory

Documents

NASA TECHNICAL MEMORANDUM...NASA TECHNICAL MEMORANDUM PASSIVE OPT1 CAL SAMPLE ASSEMBLY (POSA): FINAL REPOkT By Roger C. Linton, Edgar R. Miller, and hlichael Susko Space Sciences Laboratory