Response of Elastomer Seal Materials to SolidRocket Exhaust Emissions

Henry C. de Groh, III∗

NASA John H. Glenn Research Center at Lewis Field, Cleveland, Ohio 44135

DOI: 10.2514/1.A32488

To explore the effects of solid rocket motor emissions on spacecraft docking seals, a set of elastomer seals and sheet

material were placed in the plume during an open-air ground-based test firing of one of NASA’s solid rocket jettison

motors. The seal specimens were placed 86 ft (26.2 m) from the nozzle during an approximately 1.5 s firing outdoors.

The conditions near the seals were generally hundreds of pounds per square foot of dynamic pressure and

temperatures greater than 400°F (204°C) with high plume velocities. Worst-case flight conditions were imposed;

however, high-altitude, near-vacuum conditions were not imposed. Thus, the chemistry, temperature, and pressures

of the combustion products are expected to be slightly different compared to flight conditions. Because this was a

ground-based test done outdoors, the specimens had the opportunity to be soiled by dusty winds, and it is possible

contaminants on the seals may have come off after the firing and prior to examination and testing. The goal was to

determine if exposure to the plume from the firing would physically damage the seals. Overall, the silicone-base

elastomer seals were not measurably damaged by the emissions; leak rates were unaffected.

I. Introduction

NASA is currently developing docking mechanisms and seals fortheir next manned spacecraft [1,2]. The docking mechanism

and seals are expected to be located at the nose of a conical capsulesimilar in shape to the crewmodules used during the Apollo program[3]. One of the docking systems being developed is called theinternational Low Impact Docking System (iLIDS). ILIDS uses a setof two silicone-rubber seals. As shown in Fig. 1, the nose of the crewmodule is topped with a launch abort system (LAS), which isequipped with a solid rocket jettison motor (JM) designed to separatethe LAS from the crewmodule during a successful launch. The JM isshown firing in Fig. 1b. The LAS also has a launch abort motorsystem to propel the crew to safety during some emergency scenarios[4,5]. The abort motors are not firing in Fig. 1b. During nominalflight, the nose of the capsule is expected to be exposed to emissionsfrom the JM during the launch abort tower nominal jettison. There isconcern that these emissions might damage the docking seals.Covering the nose of the crewmodulewith a shield to protect the sealsand other parts from damage from the JM’s solid rocket plumes isbeing considered, but is expensive, adds weight, and creates otherrisks associated with the need to later jettison this nose shield. Theobjective of this work was to determine if and how docking sealsmight be damaged by nominal JMemissions. To explore the effects ofJM emissions on the seals, a set of seals and seal materials in sheetform were placed in the downstream motor plume emissions duringan outdoor, open air, full-scale gound-test firing of one of four JMnozzles. Because only one nozzlewas being tested, the JMmotor wasone-quarter scale. The system used by Aerojet to test-fire the JM iscalled BAllistic Test and Evaluation System (BATES). This was thefourth BATES test of JM hardware designs; thus, this test firing issometimes referred to as BATES-4. Prior BATES motor tests at theU.S. Air Force Research Laboratory are summarized by Geisler andBeckman [6].The seal specimens were placed 86 ft (26.2 m) from the nozzle

during the approximately 1.5 s firing. The conditions in theneighborhood of the seals during the firing are proprietary, but were

generally hundreds of pounds per square foot of dynamic pressure,temperatures in excess of 400°F, with high plume velocities.Although this ground-based test was designed to simulate flightnominal separation conditions, several important differences existed:the test did not simulate high-altitude, near-vacuum conditions;hence, the chemistry, temperature, and pressures of the plume areexpected to be slightly different. The teams at NASA, LockheedMartin, and Aerojet did their best to impose what they believed to bethe worst-case flight conditions (in terms of impingement angle anddistance between nozzle and specimens) at the time of the test.Presented are the effects of the emissions on the seals, includingvisual inspections, scanning electron microscopy (SEM) analysis ofresulting contaminants, and pre- and post-exposure leakage tests ofsilicone elastomer seals.Prior work on the effects of solid rocket emissions on elastomer

seals could not be found in literature. It is believed that this lack ofprior published work is due in part to the rarity and expense of suchsolid rocket test firings and safety protocols associated with them,and the sensitive, proprietary nature of such tests. Static cryogenicseals for launch vehicle applications are summarized in [7]. Thefailure of o-ring seals that were the primary cause of the Challengerdisaster are presented in [8]. Vacuum leak rates of seals designed forspacecraft air locks are presented by Trout [9]. Prior work on theeffects of the space environment on silicone rubber and elastomerseals can be found in [10–12]. Lynda R. Estes did work related tospace shuttle window damage from the jettison motors that pushaway the solid rocket boosters (SRB) from the main fuel tank duringlaunch, after the SRBs are spent. In [13] Estes reported that theemissions coming from the SRB’s jettison motors “sandblasted” thespace shuttle’s windows. A significant coatingwas not deposited, butphysical abrasion caused hazing and damage. Reports such as thishelped motivate the exposure testing of the docking seal materials toJM emissions. The emissions of interest from the LAS JM are ferrouschloride (FeCl2) and zirconium oxide (ZrO2). All other JM emissionsare expected to be volatile gasses. Ferric chloride (FeCl3), is amoderately strong acid, and is used as a flocculent and etchant forcopper. The compatibility tables in Parker’sO-ringHandbook (2000)indicate that silicone rubbers are rated as fair for use with FeCl3,where fair means usually adequate for static seals [14]. Data detailingthe compatibility of silicone rubber and FeCl2 could not be found;however, FeCl2 is less corrosive than FeCl3, and silicone rubber has acompatibility rating of fair with other ferrous compounds, such asferrous iodide and ferrous sulfate [14]. There are no data that indicatetheFeCl2 the JM is expected to producewill chemically reactwith theelastomer seal materials.

Received 24 August 2012; revision received 15 January 2013; accepted forpublication 14 February 2013; published online 9 July 2013. This material isdeclared a work of the U.S. Government and is not subject to copyrightprotection in the United States. Copies of this paper may be made for personalor internal use, on condition that the copier pay the $10.00 per-copy fee to theCopyright Clearance Center, Inc., 222RosewoodDrive, Danvers,MA01923;include the code 1533-6794/13 and $10.00 in correspondence with the CCC.

*Senior Materials Research Engineer, Advanced Metallics, 21000Brookpark Rd.

AIAA Early Edition / 1

JOURNAL OF SPACECRAFT AND ROCKETS

Dow

nloa

ded

by N

ASA

GL

EN

N R

ESE

AR

CH

CE

NT

ER

on

Febr

uary

11,

201

4 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/1.A

3248

8

Sections detailing the experimental procedures, results, andconclusions follow. Details associated with the specimens andproperty testing, JM test conditions, inspections and chemistryanalysis, and seal leakage testing are provided. Pre- and post-testmeasurements of durometer, mass, and surface finish are presentedalong with analysis of damage and debris, and their effects on sealleakage.

II. Experimental Procedures

The experimental procedures covered will include specimens andproperty testing, JM test conditions, visual inspections and chemistryanalysis, and seal leakage testing.

A. Specimens and Property Testing

Specimens were made from the following silicone elastomers:1) S383-70, a rust-colored compound with a Shore Hardness Adurometer rating of 70, made by Momentive and supplied by Parker,CSS-Division, San Diego, California [15] 2) S383-40, a rust-coloredcompound with a Shore Hardness A durometer rating of 40, made byMomentive and supplied by Parker; 3) ELA-SA-401, a blondcompound made and supplied by Esterline, Kirkhill-TA Co., Brea,California; and 4)XS3090-01, a very dark brown compoundmade bySilmix-Wacker and supplied by Parker.Five seals and four elastomer sheet specimens were exposed to JM

emissions. The mass, durometer, and surface finish were measuredbefore and after exposure to JM emissions. Table 1 lists and describesthe specimens exposed. Also shown in Table 1 is the atomic oxygen(AO) fluence the specimen had been exposed to prior to the JM test.This AO treatment is given to docking seals prior to use to decreaseadhesion [16,17]. The AO fluence was measured using Kapton H,mounted on heavy paper, following theAmerican Society for Testingand Materials standards [18].The pre-and post-test mass ofmost of the specimenswasmeasured

twice in grams, on a scale with a precision of at least 0.001 g, andaveraged. The mass of one of the 12-in.-diam seals, specimen 962,and two of the sheets, specimens 981 and 982,were notmeasured dueto time constraints prior to the JM test. Our analysis of the effectsof the rocket emissions on mass were made based on the otherspecimens, which were sufficient.The pre- and post-test hardness wasmeasured on the Shore A scale

using a Rex durometer gauge. The calibration of the durometer gaugesystem was confirmed using known standards prior to eachcampaign. The durometer measurements were taken from fourdifferent locations on each specimen and averaged. For double sealspecimens (962, 963, 930, −026, and −030), the durometer of eachseal was measured four times and all eight measurements for thatdouble seal were averaged. Because of time constraints, the pre-testdurometer measurements for specimens 962, 981, and 982 were notdone. This had no impact on our conclusions because the otherdurometer measurements sufficiently showed the rocket emissionshad no effect on hardness.The surface roughness of the sheet specimens 966 and 967 were

measured using a PocketSurf III from Federal Products Co. (nowMahr Federal, Inc., Providence, RI) on the Ra setting.†TheRa settingprovides the arithmetic average height of irregularities measuredfrom a mean line within the evaluation length. The calibration of theinstrument was checked using a Ra � 120 μin. standard and apreviously measured Ra � 11 μin. aluminum block. Two sets offour measurements were made on each sheet; one set of fourmeasurements wasmade parallel to the sheet casting seam, or texture,and one set perpendicular to the sheet casting seams or texture. Allmeasurements were then averaged for each sheet.

B. JM Test Conditions

The JM test firing was accomplished at Aerojet’s test facility inSacramento, California on 23 September 2010. As shown in Fig. 2,elastomer sheet and seal specimens were attached, along with avariety of other specimens, to a 6-by-4-ft aluminum frame. The framewas mounted approximately 50 ft up on awooden pole, with the poleplaced 70 ft from the exit of one of JM’s four nozzles (this was a full-scale single nozzle test; thus, only one of four nozzles was firedduring this test). Because one of four nozzles was being fired, themotor was scaled down to one-quarter. The JM was mountedhorizontally, with the exhaust plume directed up approximately35 deg. It appeared from movie images taken during theapproximately 1.5-s-long test that the center of the emissions hitthe specimens directly. The force of the emissions appeared to bend

Fig. 1 a) Schematic of the Aries and Orion integrated stack, with theLAS topping Orion, and b) an artist’s image of the JettisonMotor firing.

†Pocket Surf III, AbsoluteMobility for Surface RoughnessMeasurements,product description literature, Mahr Federal, Inc., Providence, RI. Dataavailable at http://www.mahr.com/scripts/relocateFile.php?ContentID=1248&NodeID=2410&FileID=8727&ContentDataID=29786&save=0 [retrieved16 April 2013].

2 AIAA Early Edition / DE GROH

Dow

nloa

ded

by N

ASA

GL

EN

N R

ESE

AR

CH

CE

NT

ER

on

Febr

uary

11,

201

4 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/1.A

3248

8

the pole back about 7 ft in the neighborhood of the specimen testframe. The exhaust gases appeared very dark and dirty, like densediesel exhaust. The conditions in the neighborhood of the sealsduring the firing are proprietary, but were generally hundreds ofpounds per square foot of dynamic pressure, temperatures in excessof 400°F,with high plumevelocities.Although this ground-based testwas designed to simulate separation conditions, several importantdifferences compared to in-flight conditions existed. The test did notsimulate high-altitude, near-vacuumconditions; hence, the chemistryof the combustion products is expected to be slightly different, as arethe temperatures and pressures of the plume. The teams at NASA,Lockheed Martin, and Aerojet did their best to impose what theybelieved to be worst-case flight conditions at the time of the test.

C. Visual Inspections and Chemistry Analysis

The elastomer sheet and seal specimens were carefully inspectedfor damage and debris after the JM test firing. Optical images ofthe specimens were captured before and after the firing using aconventional camera (Canon EOS with either a Canon EFS 18–55 mm or Canon 100 mm macro lens). Infrared (IR) spectroscopywas used in an effort to detect changes in the surface chemistry of thetwo sheet specimens −026 and −030. Before and after the JM firing,the surfaces of the sheets were measured using a Nicolet 380 FT-IRspectrometer‡ fitted with a SMART Omni sampler single passattenuated total reflectance (ATR) accessory using a Ge crystal.Scanning electron microscopy (SEM) and energy dispersivespectroscopy (EDS) were used to characterize the surfaces of twoelastomer sheet specimens after JM testing.

D. Seal Leakage Testing

Afixture, known as the impact specimen flow fixture, consisting oftwo large flat plates, was used to test the before and after leak rates ofthe Gask-O-Seal specimens −026 and −030. The space between theinner and outer seals was pressurized to a relative pressure differenceof 14.7 lb∕in:2, thus testing the leakage of the outer seal only. Thepressure was measured over time and a pressure decay method usedto determine leakage [19].

III. Results

A. Elastomer Properties

1. Durometer

The pre-test and post-test durometer measurements are presentedin Table 2. Because all but one pre- and post-test durometer averagesare within their 95% confidence intervals, no statistically significantdifference in hardness was observed between the pre- and post-test

specimens. The slight rise in hardness for specimen 963 is notconsidered to be significant or credible because the hardness of all theother specimens (in particular, the other Gask-O-Seals, which usedthe same compound, specimens −026 and −030) was essentiallyunchanged.

2. Mass

The pre-test to post-test mass change of the specimens is presentedin Table 3. The mass of all specimens increased slightly except forspecimen 930, which had a slight mass loss. All mass changeswere less than 0.1%. Mass gains were likely caused by surfacecontamination. The slight mass loss of specimen 930 was likely dueto normal outgassing and differences in compound moisture content.Vacuum outgassing of 0.1% has been shown to be typical [20], andvariations in water content can be expected for silicone rubber [21].The main point is that the heat and force of the JM emissions did notcause measurable burning or erosion of the elastomers.

3. Surface Finish

Figure 3 shows the average surface finish of S0383-70 (specimen966) and ELA-SA-401 (specimen 967) sheets tested before andafter exposure to the JM test firing. The absence of damage observedin the visual examination is confirmed by the surface roughnessmeasurements. Exposure to the JM emissions did not cause a changein the surface roughness of the elastomers. The uncertainty of theroughness measurements is represented by the error bars in Fig. 3,which were set equal to the standard deviation of the eightmeasurements taken of each specimen.

B. General Damage and Debris

In general, the impingement of the JM emissions appeared to do nodamage to the specimens. Figures 4–6 present characteristic pre- and

Table 1 Description of specimens

Specimennumber

Description Pre-test AO treatment,atoms∕cm2

962 12-in.-diam double seal of S383-70 silicone rubber, approximate bulb width 0.28 in. and height 0.33 in. ID:12in2PG2P70-7-001, incorrect size

1.25E� 20

963 Gask-O type 12-in.-diam double seal of S383-70 silicone rubber, approximate bulb width 0.1 in. and height 0.15 in.5950LIDS10920-002 etched on the surface of the metal retaining ring, other ID: EDU58-3, s/n 207253-3-002

1.28E� 20

930 12-in.-diam double seal of ELA-SA-401 silicone rubber, approximate bulb width 0.35 in. and height 0.33 in. ID: KH2P,s/n: LIDS6016-008

1.30E� 20

−026 Gask-O type 4-in.-diam double seal of S383-70 silicone rubber, approximate bulb width 0.1 in. and height 0.15 in. ID:5950LIDS10851 REVA-026

1.28E� 20

−030 Gask-O type 4-in.-diam double seal of S383-70 silicone rubber, approximate bulb width 0.1 in. and height 0.15 in. ID:5950LIDS10851 REVA-030

1.23E� 20

966 3 × 3 in: sheet 0.21 in. thick, Momentive compound S0383-70, cure 4Q07, s/n 00002 1.00E� 20967 3 × 3 in: sheet 0.21 in. thick, Esterline compound ELA-SA-401, sheet D28147 1.00E� 20981 3 × 3 in: sheet 0.21 in. thick, 207048-6 Rev A, cure 2Q10, batch 10E001,Momentive compound XS3088-02, S383-40 0982 3 × 3 in: sheet, 0.21 in. thick, 207048-7 Rev B, cure 2Q10, batch CH118122, Silmix-Wacker compound XS3090-01 0

Fig. 2 Schematic of JM test firing andplacement of specimens (artworkborrowed from a presentation created by Kurtis R. Long, NASA AmesResearch Center, Feb. 2011).

‡Thermo Scientific Nicolet 380 FT-IR Spectrometer, Product Specifica-tions, Thermo Electron Scientific Instruments, LLC, Madison, WI. Dataavailable at http://www.deltacollege.edu/emp/ckim/IR380_SOP_WWW/productPDF_52266.pdf [retrieved 16 April 2013].

AIAA Early Edition / DE GROH 3

Dow

nloa

ded

by N

ASA

GL

EN

N R

ESE

AR

CH

CE

NT

ER

on

Febr

uary

11,

201

4 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/1.A

3248

8

post-test images of the specimens. The JM test firing was doneoutdoors, in a dry, somewhat dusty climate.With this inmind, a smallamount of soiling of the specimens was expected (and seen duringpost-test examination) due simply to their unprotected presence in thegeneral environment. The most significant contaminants that canmost likely be attributed to the emissions were small black specks,which are shown in Figs. 4b and 6b. These bits of black scattered onthe specimens were soft and rubbery, frequently round and shiny, and

sometimes a bit translucent. Figure 4b shows a needle being pressedinto one of these black particles. No heat damage of any kind wasfound on any of the specimens.

C. Post-Test Chemistry

1. Scanning Electron Microscopy and Energy Dispersive Spectroscopy

SEM and EDS were used to characterize the surfaces of elastomerspecimens 982 and 966. Figure 7 shows optical images of each 3-by-3-in. sheet after JM testing. No discoloration or ablation was visiblewhen viewed optically using 30X magnification. A baseline samplewas made for each specimen by cutting away the top 0.5 mm surfacein order to expose an unaffected surface. Energy dispersivespectroscopy detected silicon, oxygen, carbon, and traces of iron andcalcium in both baseline specimens 982 and 966. Silicon, oxygen,and carbon are fundamental elements associated with silicone-basedmaterials. Iron is often used as a coloring agent. After JM testing,zirconium oxide spheres ranging in size from submicron toapproximately 20 μmwere detected on the surface of specimen 982.Spectra for these particles are shown in Figs. 8 and 9. The primarysolid combustion products expected from the JMareFeCl2 andZrO2.The zirconium oxide found on specimen 982 is believed to be fromthe JM emissions. The black particles previously mentioned andshown in Fig. 6b were not subjected to SEM or EDS analysis due totheir much lower frequency compared to the smaller particlecontaminants. The SEM and EDS analyses did not show any signs ofphysical damage or chemical reaction resulting from exposure to theJM emissions.Sodium, chlorine, and potassium deposits were widespread in JM

tested specimen 966. Some zirconium oxide particles were alsodetected. Higher magnification of the Na, Cl, and K deposits show adendritic structure, which may have formed upon cooldown. Somezirconium oxide spheres were detected; however, the electron beamfrom the SEM caused many of these spheres to scatter, makingdetermination of their abundance difficult. Unlike specimen 966,specimen 982 was not pretreated with AO. Atomic oxygen is used todecrease the adhesive characteristics of the elastomer; thus, specimen982 is expected to be more sticky than specimen 966. This differencein AO pretreatment is believed to be the reason the zirconium oxide

Table 3 Pre- to post-test mass change

Specimen Mass change, %

962 –

963 0.0121930 −0.0195−26 0.0226−30 0.0191966 0.0197967 0.0754981 –

982 –

Fig. 3 Sheet specimen roughness of specimens 966 and 967.

Fig. 4 Images of specimen 930: a) pre-test, and b) post-test. The width of the seal is 0.35 in.

Table 2 Elastomer hardness before and after exposure to JM emissions

Specimen Pre-test average durometer,Shore A

Standarddeviation

Confidence interval at95%

Post-test average durometer,Shore A

Standarddeviation

Confidenceintervalat 95%

962 67.9 1.5 1.27963 71.0 1.2 1.01 75.1 1.5 1.26930 39.4 1.7 1.41 39.3 1.6 1.36−26 73.2 1.4 1.14 73.0 3.7 3.12−30 73.8 0.7 0.58 73.4 2.5 2.08966 71.8 0.5 0.79 71.6 0.5 0.81967 43.9 0.7 1.16 44.9 0.1 0.14981 44.1 1.3 2.12982 45.1 0.7 1.16

4 AIAA Early Edition / DE GROH

Dow

nloa

ded

by N

ASA

GL

EN

N R

ESE

AR

CH

CE

NT

ER

on

Febr

uary

11,

201

4 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/1.A

3248

8

Fig. 5 Images of specimen −030: a) pre-test, and b) post-test. Width of the seal’s bulb, not including its support webbing, is 0.1 in.

Fig. 6 Images of specimen 966: a) pre-test with 0.25-in.-diam mounting hole, and b) post-test.

Fig. 7 Optical images of elastomer specimens 982 and 966 after JM testing.

Fig. 8 Exposed specimen 982.

AIAA Early Edition / DE GROH 5

Dow

nloa

ded

by N

ASA

GL

EN

N R

ESE

AR

CH

CE

NT

ER

on

Febr

uary

11,

201

4 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/1.A

3248

8

spheres on specimen 982 scattered less compared to specimen 966.A few sporadic particles of stainless steel and gadolinium–gallium(Gd–Ga) were also detected on specimen 966. The Gd–Ga particlesmay be from a nearby radiator coupon that used a Ga–Gd coating.Spectra for specimen 966 are included in Figs. 10–14. Figure 12shows the dendritic nature of some of the larger Na, Cl, and Kparticles. The SEM and EDS analyses did not show any signs ofphysical damage or chemical reaction resulting from exposure to theJM emissions.

2. IR Spectroscopy (Surface Chemistry)

The results of the IR spectroscopy measurements of the surfacechemistry of specimens 966 and 967, before and after the JM testfiring, are shown in Fig. 15. In IR spectroscopy, changes in chemistry

are shown by characteristic changes in the relative absorbance peaks.The pre- and post-JM test firing absorbance profiles for the twocompounds appear unchanged, indicating no measurable change insurface chemistry due to the rocket emissions.

D. Seal Leakage Rate

The leakage rates of two 4-in.-diam Gask-O-Seals (specimens−026 and −030) were tested before and after JM testing. Both sealswere exposed to atomic oxygen, as indicated in Table 1, prior to anytesting. The pre-test leakage for seal specimens −026 and −030 was1.58 × 10−5 and 1.25 × 10−5 lbair∕day, respectively. The leakageafter the seals were exposed to the JM emissions was 1.1 × 10−5 and1.2 × 10−5 lbair∕day, respectively. The precision and bias errorassociated with the leakage measurements was on the order of�1%.

Fig. 9 Higher magnification of zirconium oxide particles deposited on specimen 982.

Fig. 10 Exposed specimen 966 with sodium and chlorine detected.

Fig. 11 Sphere containing zirconium and oxygen.

6 AIAA Early Edition / DE GROH

Dow

nloa

ded

by N

ASA

GL

EN

N R

ESE

AR

CH

CE

NT

ER

on

Febr

uary

11,

201

4 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/1.A

3248

8

The leak rate of the seals was not affected by the JM emissions inthis case.

IV. Conclusions

Although the Jettison Motor test did not exactly mimic nominalflight conditions, it is believed that conditions during the ground-based test were, by design, more severe than flight conditions.Specimens were examined using a scanning electronmicroscope andoptically at a variety of magnifications. These surveys showed noevidence of burning or overheating of the elastomers. Infraredspectroscopy showed no change in the general surface chemistry ofthe elastomers. The JettisonMotor emissions did not have any effects

Fig. 12 Specimen 966: higher magnification of sodium–chlorine–potassium deposit.

Fig. 13 Specimen 966 with steel, sodium–chlorine–potassium, and zirconium oxide detected.

Fig. 14 Specimen 966: Particles containing gadolinium and gallium were detected.

Fig. 15 IR spectroscopy of 966 and 967 before and after the JM firing.

AIAA Early Edition / DE GROH 7

Dow

nloa

ded

by N

ASA

GL

EN

N R

ESE

AR

CH

CE

NT

ER

on

Febr

uary

11,

201

4 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/1.A

3248

8

on the elastomer’s mass, durometer, or surface finish. The JettisonMotor emissions deposited fine particles of mainly zirconium oxideon the seal materials; however, these deposits did not negativelyaffect the leak rate of the two 0.1-in.-wide Gask-O type seals tested.Thiswork indicates that the docking sealmaterials were not damagedby the test firing of the Jettison Motor.

Acknowledgments

I appreciate greatly the dedication of theNASA, LockheedMartin,and Aerojet teams that made the test firing of the JM possible.Particular gratitude is expressed to Kurtis R. Long and VanessaAponte for their assistance and long hours dedicated to this test.Significant and artful contributions were made by Jane Bonvallet ofLockheed Martin Space Systems Company. The detailed scanningelectron microscopy and energy dispersive spectroscopy work wasdue to her. Sharon Miller and Bruce Banks very graciously providedthe state-of-the-art atomic oxygen exposures used in this study.Thanks are due to Lisa Greeney for her help with the manuscript andartwork.

References

[1] Dunlap, P., Steinetz, B., and Daniels, C., “Overview of LIDS DockingSeals Development,” 2008 NASA Seal/Secondary Air System Research

Symposium, NASA CP-2009-215677, 18 Nov. 2008, pp. 223–231.[2] Lewis, J. L., Carroll, M. B., Morales, R. H., and Le, T. D., NASA,

“Androgynous, Reconfigurable Closed Loop Feedback Controlled LowImpact Docking System with Load Sensing Electromagnetic CaptureRing,” U.S. Patent No. 6,354,540, 12 March 2002.

[3] Bednarcyk, B. A., Arnold, S. M., Collier, C. S., and Yarrington, P. W.,“Preliminary Structural Sizing and Alternative Material Trade Study ofCEV Crew Module,” 48th Structures, Structural Dynamics, and

Materials (SDM) Conference, AIAA Paper 2007-2175, Honolulu,Hawaii, 23–26 April 2007; also NASA TM-2007-214947, 2007.

[4] Hyle, C. T., “Launch Abort Philosophy for Manned Space Flights,”NASAMSC Internal NoteNos. TM-X-69805, 68-FM-104,April 1968.

[5] Idicula, J.,Williams-Hayes, P. S., Stillwater, R., andYates,M., “AFlightDynamics Perspective of the Orion Pad Abort One Flight Test,” AIAAPaper 2009-5730, Aug. 2009.

[6] Geisler, R., and Beckman, C., “The History of the BATESMotors at theAir Force Rocket Propulsion Laboratory,” AIAA Paper 1998-3981,July 1998.

[7] “Static Cryogenic Seals for Launch Vehicle Applications,” PreferredReliability Practices, Marshall Space Flight Center, Practice No. PD-ED-1208, Jet Propulsion Laboratory Office of the Chief Engineer,9 Dec. 1998; http://engineer.jpl.nasa.gov/practices/1208.pdf [retrieved16 April 2013].

[8] Rogers, W. P., Armstrong, N., Acheson, D., Covert, E., Feynman, R.,Hotz, R., Kutyna, D., Ride, S., Rummel, R., Sutter, J., Walker, A.,Wheelon, A., Yeager, C. E., and Keel, Alton G., Jr., “Report of thePresidential Commission on the Space Shuttle Challenger Accident,”Chapter IV: The Cause of the Accident, 6 June 1986, http://history.nasa.gov/rogersrep/v1ch4.htm [retrieved 16 April 2013].

[9] Trout, O. F., Jr., “Vacuum Leakage Tests of a Simulated LightweightSpacecraft Air Lock,” NASA TN-D-5864, July 1970.

[10] Dever, J. A., Banks, B. A., and Yan, L., “Effects of Vacuum UltravioletRadiation on DC93-500 Silicone,” Journal of Spacecraft and Rockets,Vol. 43, No. 2, 2006, pp. 386–392.doi:10.2514/1.15226

[11] Christensen, J. R., Underwood, S. D., Kamenetzky, R. R., andVaughn, J. A., “Atomic Oxygen Effects on Seal Leakage,” 20th Space

Simulation Conference: The Changing Testing Paradigm, NASA CP-1999-208598, Feb. 1999, pp. 195–206.

[12] de Groh, H. C., III, and Steinetz, B. M., “Effects of HypervelocityImpacts on Silicone Elastomer Seals and Mating Aluminum Surfaces,”45th Joint Propulsion Conference and Exhibit, AIAA Paper 2009-5249, Aug. 2009; also NASA TM-2009-215836.

[13] Estes, L. R., “Identification, Sourcing and Prevention of OrbiterWindow Haze,” Proceedings of the 9th Biennial ASCE/Aerospace

Division International Conference on Engineering, Construction, and

Operations in Challenging Environments Earth & Space, edited byMalla, R. B., and Maji, A., American Society of Civil Engineers,March 2004, pp. 311–316.

[14] Parker O-Ring Handbook, 2000 ed., Parker Hannifin Corp., Lexington,KY, 1999, pp. 7–22.

[15] “Evaluation of Low Temperature Parker Compound S0383-70,” ParkerO-Ring Division Material Rept. DD4005, Compound Data Sheet,Lexington, KY, 13 Feb. 1990.

[16] de Groh, H. C., III, Miller, S., Smith, I., Daniels, C., and Steinetz, B.,“Adhesion of Silicone Elastomer Seals for NASA’s Crew ExplorationVehicle,” 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference,AIAA Paper 2008-4625, 21 July 2008; also NASA TM-2008-215433,Oct. 2008.

[17] de Groh, H. C., III, Daniels, C. C., Dever, J. A., Miller, S. K., Waters, D.L., Finkbeiner, J. R., Dunlap, P. H., Jr., and Steinetz, B. M., “SpaceEnvironment Effects on Silicone Seal Materials,” NASA TM-2010-216332, April 2010.

[18] “Standard Practices for Ground Laboratory Atomic Oxygen InteractionEvaluation of Materials for Space Applications,” American Society forTesting and Materials, Standard E2089-00, West Conshohocken, PA,2006.

[19] Dunlap, P. H., Jr., Daniels, C. C., Wasowski, J. L., Garafolo, N. G.,Penney, N., and Steinetz, B. M., “Pressure Decay TestingMethodologyfor Quantifying Leak Rates of Full-Scale Docking System Seals,” 45thJoint Propulsion Conference and Exhibit, AIAA Paper 2009-5319,Aug. 2009; also NASA TM-2010-216244, Aug. 2009.

[20] de Groh, H. C., III, Puleo, B. J., and Steinetz, B. M., “Effects of AtomicOxygen andGrease onOutgassing andAdhesion of SiliconeElastomersfor Space Applications,” NASA TM-2012-217263, Feb. 2012.

[21] Velderrain, M., “Moisture Permeability of Silicone Systems Case Study#1,”NuSil Technology, LLC,Carpinteria, CA,March 2010; http://www.nusil.com/library/papers/Moisture%20Permeability%20of%20Silicone%20Systems-%20Case%20Study%201.pdf [retrieved19 April 2013].

V. BabuskaAssociate Editor

8 AIAA Early Edition / DE GROH

Dow

nloa

ded

by N

ASA

GL

EN

N R

ESE

AR

CH

CE

NT

ER

on

Febr

uary

11,

201

4 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/1.A

3248

8