This pictorial presentation reviews the post-flight analysis results from two type of hardware (tray clamp bolt heads and uhcre flight experiment tray walls) from the Long Duration Exposure Facility (LDEF). It will also discuss flight hardware for one upcoming (Effects of the Space Environment on Materials (ESEM) flight experiment), and two current flight experiments evaluating the performance of materials in space (Passive Optical Sample Assembly (POSA) 1&2 flight experiments. These flight experiments also are concerned with contamination effects which will also be discussed

Pippin, Gary

English

NASA Technical Reports Server

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Thischartistointroducethetopicscoveredin thispresentation.I will reviewthepost-flightanalysis
resultsfromtwotypesofhardwarefromtheLongDurationExposureFacility.I willalsoshowflight
hardwareforoneupcomingandtwocurrentflightexperimentsevaluatingtheperformanceofmaterialsin
space.Theseflightexperimentsal oareconcernedwithcontaminationeffectswhichwillalsobediscussed.
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Tray clamp & bolts-this NASA photo shows the tops of some LDEF tray clamp bolts. These surfaces were
analyzed post-flight for silicon containing contaminants.
I IASA National Aeronautics and
Space Administration
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Lyndon B. Johnson Space Center
Houston, Texas 77058
On-orbit view of vent holes in blanket. This NASA photo of the LDEF on-orbit shows the vents at the edge
of thermal control blankets on the European Heavy-Cosmic-Ray experiment. Adhesive under the blanket
outgassed through these vents and deposited on the tray surfaces. Our current NASA contract is to
determine the distribution of this contaminant on selected tray surfaces.
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Position of velcro/adhesive locations-This NASA photo shows the locations of the silicone which was the
source of the contamination being analyzed on our current contract. This is to show the audience the extent
of the material and the geometry of the tray interior.
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Plume-This photo taken at Boeing shows a close-up of the contamination deposit from a "leading-edge"
location from LDEF, The plume which extends down the tray wall shows that a portion of the tray wall saw
direct sunlight and atomic oxygen. This combined exposure produced the discoloration by fixing the
silicone material to the tray surface.
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This chart identifies the locations for which a detailed analysis of the amount of silicon present on the
surface was determined. E10 is an area with high solar and atomic oxygen exposure, C6 is an area of high
solar exposure and moderate amounts of atomic oxygen exposure, and A4 is an area with high solar
exposure and no atomic oxygen exposure.
Thenextseveralchartsdetailtheresultsof the measurements made on the selected surfaces from the Long
Duration Exposure Facility. These charts show the location of individual measurements and the results (the
% silicon detected at each site). Some of the data will be shown and the rest I will have as backup charts in
case someone wants to see data from a specific location. One of these charts shows a depth profile of the
deposited contaminant, showing the thickness of the deposit.

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NAS8-40581 contract status- This chart summarizes the tasks being carried out and the results-to-date. I
intend to mention that the experimental results are being compared with predictions from two different
contamination deposition models. The computer predictions will be based on the ISEM and MOLFLUX
models but the results are not yet reported. The audience at this workshop will be very familiar with the
capabilities of these two computer models.
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This chart summarizes a pair of companion experiments which are currently being flown on the MIR space
station. These experiments are the Passive Optical Sample Assembly(POSA) I & II. I will present a little
of the background of these experiments, who is involved, and what we plan to do upon retrieval.
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This chart describes the types of materials being flown on the POSA II experiment, for which I am the
technical leader. I will describe why some of these materials have been chosen and what we expect to learn
in general terms.
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POSA I, pre-flight This NASA photo shows the POSA I experiment with all specimens mounted, prior to
flight. I intend to point out some of the Boeing specimens on this experiment.

POSAII,pre-flightThis photo taken at Boeing shows the assembled POSA II sample holder. I intend to
point out some of the different material types being flown, the atomic oxygen concentrators, pre-
contaminated specimens, and passive means being used to obtained some time varying exposures for
selected material types.
National Aeronautics and
Space Administration STS079-321-035
L_,'ndon 8 Johnson Space Center
Houston, Texas 77058
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POSA I & II, on-orbit This NASA photo shows the POSA experiments mounted on the docking module
attached to the MIR space station. This is the best view available of these two experiments and was taken
from a camera in the payload bay of the Space Shuttle.
National Aeronautics ancl LynOon B Johnson Space Center
Space Administration $TS079-32_-00 | Houston. Texas 77058
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POSA I, close-up, on-orbit This NASA photo shows a close-up of the POSA I experiment during the STS-
079 rendezvous with MIR. This was about 5 months into the exposure period. The hardware looks to be in
excellent condition.
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Japanese Flight Demonstration This chart shows the people involved in a Space Shuttle experiment being
flown this July
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This chart shows the material specimens being flown on the Effects of the Space Environment on Materials
experiment. I intend to briefly mention the rationale behind the selection of these specimens, emphasizing
that the solar concentrator and atomic oxygen concentrators are attempts to extend the range of
measurement conditions generally achieved on Space Shuttle flights.

ESEM,pre-flightThisNASAphotoshowsthematerialsampleholderfortheESEMexperiment,complete
withthespecimensmountedinplace.Thisshowstheeffectiveuseoftheareavailableforthisexperiment
andI willdiscussthedetailsofthelayoutofthesamples.
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This NASA photo shows a close-up of the atomic oxygen concentrators. The acceleration factors expected
and issues relating to energy changes in atoms reflecting off the walls of the collectors will be discussed.
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This chart is a background chart which will be used to describe the measurements on the LDEF tray clamp
bolt heads. It is to show the detailed le_'el of analysis carried out to arrive at the results shown on
subsequent charts.
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Figure G-27. Silicon 2p spectrum for bolt F1-6b, position 1.
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This chart is a detailed energy spectrum obtained using surface X-ray photoelectron spectroscopy(XPS).
This spectrum is for silicon and shows the separation of the measured peak into its two components
representing inorganic and organic based silicon deposits.
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Figure G-28. Carbon ls spectrum for bolt F1-6b, position 2.
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This chart shows a reference carbon ls spectrum used as a standard to precisely establish the energies of the
peaks shown in the previous silicon XPS measurement.
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Figure 17. Results of high resolution ESCA measurements on selected stainless steel bolt
heads from LDEF.
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This chart summarizes the results of the XPS measurements made on selected tray clamp bolt heads from
the Long Duration Exposure facility. The results indicate the presence of silicone based material for areas
which had considerable atomic Oxygen exposure on-orbit, indicating a source of silicone contamination
after the LDEF was captured by the Space Shuttle.
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Contamination from Gasket Material This NASA photo shows contamination deposits which can be
attributed to pre-flight outgassing by silicone gasket material used as part of the tray covers for the LDEF
experiment trays both pre- and post-flight. The discoloration is due to the actual on-orbit exposure
conditions.
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This summary slide is to relate findings from the experiments described in this talk to issues of importance
to people building commercial satellites.


LDEF Materials/Contamination

Abstract

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