Materials and Processes SME Initiative Materials and Processes Division ESA/ESTEC/TOS-QM Mve/qmc 1 Space Environment Effects : Manned Volumes

Materials and Processes DivisionESA/ESTEC/TOS-QM

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Materials and Processes SME Initiative

NUMEROUS PROBLEMSPARTICULARLY

INSULATION/GASKETING

DEGRADATION OFMATERIAL FUNCTION

OFFGASSING/AGEING/CORROSION

COMBUSTION

BIOLOGICALGROWTH

SMELL

LIFE SUPPORTINGATMOSPHERE

TOXIC GASES

LOSS OF MATERIALFUNCTION

TOXINES

AGRESSIONS TOLIFE

CATASTROPHICFAILURES

DISEASES

DISCOMFORT

Space Environment Effects : Manned Volumes


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Offgassing


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ECSS-Q-70-29 (former ESA PSS-01-729) : The determination of offgassing products from materials and assembled articles to be used in a manned space vehicle crew compartment

Purpose:Determine the identity and quantity of volatile offgassed products from materials and assembled articles.

Material screening test

• Quantity of Carbon Monoxide [g/g]• Quantity of total organics (pentane equivalent) [mg/g]• Identification of contaminants in excess of 10 mg/g of material

General test for materials/assembled articles

• Identification and quantification of all contaminants present• Use of T-values for acceptance

Offgassing test (1)


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Offgassing test (2)

• Acceptance Limits• Screening test

– Carbon Monoxide : <25 mg/g material– Total Organics : <100 mg/g material

• General test– No definitive acceptability defined by this test. Data are evaluated

by the Safety Office of the relevant project • for assessment of toxic hazard due to volatile

contamination evolved from the item under test• for assessment of the impacts on the potential

toxicity of the total quantity of offgassed products from all contaminant generating items for a given mission


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Offgassing test (3)

– Following primary acceptance criteria are relevant:

– The quantity of each individual offgassed product shall result in a predicted Spacecraft concentration below the SMAC value

– Toxic Hazard Index (T) shall not exceed 0.5. T is determined by calculating the ratio of the projected concentration of each offgassed product to its SMAC value and summing up these ratios for all offgassed products

T = C1/SMAC1 + C2/SMAC2 ..... + Cn/SMACn


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General test conditions

• Temperature 50 C

• Atmosphere : synthetic air or clean/dry air

• Pressure : 1 Atmosphere at 50 C

• Duration : 72 hrs

• Mass (material) 5g/liter test volume

Sampling : +/- 250 ml gas on trap after max. 12 hrs recovery to reach RT; flow rate sampling is +/- 25 ml/min.

Offgassing test Procedure (1)


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Test chambers

Different facilities are available e.g.:

Heraeus ovens 128 and 718 litersGlass bottles 1, 2.5 and 5 liters

Analyses:

Screening:TO/COGC with Methaniser and Flame Ionisation Detector

General testPre-concentrated samplingDesorption system : Model MW-1A from Rektorik (CH)GC with DB5MS from JW column (60m, diam 0.25mm, film 0.25 m) Mass spectrometer model Profile from Kratos (UK)



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Screening test


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Odour Test

NASA-STD-6001 (former NHB 8060.1C)

Purpose

Determine if the odour is objectionable or revolting

• Odour of a material or assembled article is objectionable or revolting if an average of 2.5 or higher on an odour characteristic scale is obtained (0:undetectable, 1:Barely detectable, 2: Easely detectable, 3: objectionable,4: revolting).

• Sample preparation is the same as for Offgassing test

• Test panel shall consist of 5 qualified persons


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Flammability


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• Identify flammable materials used, their amounts, thickness, exposed surface, exposure environment

• Identify propagation paths for exposed materials (including housing)

• If configuration is container, evaluate its capability to contain an internal fire

• If unacceptable configuration through the configuration assessment, there are two options:

Use fire break concepts to reduce flammability hazard by isolating the flammable materials

Conduct a test to show acceptability of configuration

Flammability configuration assessment (1)


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YES

ARE THERE ANY FLAMMABLE MATERIALS OR MULTIPLEAPPLICATIONS OF FLAMMABLE MATERIALS INAMOUNTS>0.1 LB OR 10 SQ. INCH IN MANNED COMPARTMENTS

OR>1.0 LB OR 12 LINEAR INCHES IN OTHERCOMPARTMENTS?

ACCEPTABLE

ARE EXTERIOR SURFACES AND ANYEXTERNALLY ATTACHED MATERIALSFLAMMABLE?

COULD A FIRE PROPAGATE ON THE SURFACE MORE THAN 6”IN MANNED COMPARTEMENTS OR 12” IN OTHERCOMPARTMENTS?

UNACCEPTABLE;MODIFICATIONREQUIRED (SEE GUIDELINES)

IS IT A CONTAINER?

WILL THE CONTAINER CONTAIN ANY INTERNAL FIRE?(SEE EXAMPLE CONTAINER CASES)

DOES THE CONTAINER CONTAIN AIR?

ARE INTERNAL IGNITION SOURCES PRECLUDED WHILETHE CONTAINER IS LOCATED IN THE ORBITER?

UNACCEPTABLE;MODIFICATIONREQUIRED(SEE GUIDLINES

ACCEPTABLE

ACCEPTABLEYES

ACCEPTABLENO

ACCEPTABLE

NO

NO

NO

YES

YES

YES

YES

YES

NO

NO

NO

Flammability configuration assessment (2)


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• Limitation of flammable materials by replacement with a non flammable one

• Restriction of propagation paths through

Covering of flammable materials with a nonflammable one

Separation of flammable materials (avoid propagation)

How to reduce flammability hazards


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Upwards Propagation Test (1)

ECSS-Q-70-21 (Former ESA PSS-01-721) : Flammability testing for the screening of space materials

Purpose :Determine if a material, when exposed to a standard ignition source, will self-extinguish and not transfer burning debris, which can ignite adjacent materials

Test criteria :Self extinguishing within 15 cmNo transfer of burning debris Burn Propagation time

Sample dimensions : 300 x 64 mm, worst case thicknessTest atmosphere : depends on application (24% O2 or more…)


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NiCr

Ignitor

TestSpecimen

64 mm

300

mm


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Wire Flammability test (1)ECSS-Q-70-21 (Former ESA PSS-01-721) : Flammability testing for the screening of space materialsPurpose :Determine if a wire insulation system, when exposed to an external ignition source, will self-extinguish and not transfer burning debris, which can ignite adjacent materials

Acceptance criteriaPrior to flame application, while heating wire to maximal operation T, no spontaneous combustion, splitting insulation nor baring conductorDuring ignition and combustion no flaming droplets/particlesAfter burner is extinguished, cease flaming within 10 s and within a total burn length of 150 mm

Sample dimensions : 5 x 1m

Test atmosphere : depend on application (20% O2 or more…)


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Wire Flammability test (2)


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Wire Flammability test (3)

Documents

Materials and Processes SME Initiative Materials and Processes Division ESA/ESTEC/TOS-QM Mve/qmc 1 Space Environment Effects : Manned Volumes