# Presentation: 346621

## Section 30

_***Section 30***_
***Contamination***

*** ******. . . Michael Woronowicz***
*Swales Aerospace *

## Outline

***Outline***

***Contamination Perspective***
***Thermal Balance/Thermal Vacuum Test***
***Contamination-related equipment***
***Measurements***
***Pulsed Plasma Thruster***
***Inertial Reference Units***
***Delta Fairing Cleanliness ***
***Purge Requirements***
***Cleanliness Maintenance***
***Open Issues***

## Contamination Perspective

***Contamination Perspective***

***Contamination staff concerned with deposition of foreign materials***
***Particulates***
***Molecular films***
***On sensitive surfaces***
***Instruments***
***Optics***
***Thermal control surfaces***
***Sources Considered for EO-1***
***On-orbit***
*Outgassing from non-metallic materials*
*PPT operations*
***During ground operations***
*Contaminants in ambient atmosphere*
*Residue from handling, testing*

## T/V II Parameters

***T/V II Parameters***

***Chamber 225 instrumentation ***
***2 TQCMs (usually collected @ -65 °C)***
***2 instrument scavenger plates (usually @ -65 °C)***
***Chamber scavenger plate @ 90 K***
***Coldfinger (collected @ 90 K for 8 hrs)***
***TQCM’s measured outgassing rates from instrument interiors***
***Kapton******® ******sheets isolated instrument outgassing from general S/C***
***Differential measurements for aperture open vs. aperture closed indicate instrument internal outgassing rates***
***Instrument scavenger plates intended to preferentially collect instrument NVR for chemical composition analysis & ID***

## T/V II TQCM Placement (ALI)

- TQCM #1

- ALI Nadir Deck
- Heater Plate

- Kapton Isolation Sheet

- ALI Outgassing
- Measurement
- Arrangement

- Scavenger Plate
- (behind sheet)

## T/V II TQCM Placement (Hyperion)

- TQCM #2

- Scavenger Plate

- Kapton Isolation Sheet

- Hyperion

- Hyperion Measurement Arrangement

## T/V II Initial Results

***T/V II Initial Results***

***Hyperion NVR mass loss rates condensable @ -65 °C***
***1.6 x 10******-7****** g/s (outgassing mode, final hot plateau, 20 °C)***
***1.4 x 10******-6****** g/s (outgassing mode, final hot plateau, 30 °C)***
***ALI NVR mass loss rates condensable @ -65 °C***
***1.3 x 10******-6****** g/s (outgassing mode, final hot plateau)***
***Other results, refinements currently still being processed***
***Desorption demonstrated during TQCM warm-up to 0 °C***
***during final T/V cycle hot plateau ***
***Post-test chemical analyses***
***Same constituents and quantity as T/V #1; no unexpected contaminants have been introduced on spacecraft bus***
***Instrument samples lost due to S-Band Transponder testing (during chamber re-evacuation event, 7/19/00; cannot identify instrument sources (outgassing levels acceptable))***

## Pulsed Plasma Thruster

***Pulsed Plasma Thruster***

***Concern over S/C degradation due to plume products from PPT firing***
***uses Teflon******®****** for fuel ************  fluorinated products possibly corrosive to S/C matls.***
***some plume product fraction will be ionized***
***Effects measured on S/C mockup with strategically-placed S/C materials during lifetime acceptance test***
***Test performed in vacuum at NASA-Glenn***
***Results indicate negligible degradation after 10******5****** pulses***
***Reduce risk concerns by operating at end of mission***

## IRU Helium Issue

***IRU Helium Issue***

***Inertial reference units (IRU’s) absorb helium, changing required driving voltage***
***IRU He desorption rate considerably less than absorption rate***
***Exposure incidents during I&T prompted purge modifications***
***Research-grade bottled N******2****** replaced with LN******2****** boiloff***
***Relatively permeable teflon******®****** tubing replaced with impermeable Cu tubing***
***Ambient air periodically monitored for helium concentration***
***Assembly removed, placed under N******2****** purge at Swales during current MAP testing to reduce risk from elevated He concentrations***
***Future risk includes possible exposure under flight vehicle environment***
***This has been mitigated to the maximum extent possible by using stainless steel tubing on stand wrapped tubing in the fairing.***

## Launch Vehicle Cleanliness

***Launch Vehicle Cleanliness***

***Fluoroglide used on Delta II fairing separation rails***
***Teflon******®****** spray application***
***facilitates fairing assembly process***
***creates particulate hazard during fairing separation***
*seen on Globalstar-5 & Globalstar-7 separation videos*
***Concern regarding relative location of S/A CSS to fairing separation plane***
***Minimize technical and schedule risk by using fairing w/o Fluoroglide***
***KSC contamination personnel working issue with Boeing***

## Fairing Separation Issue

**Fairing**

**Fairing Separation Plane**

**Coarse Sun Sensors**

**Solar Array**

## Purge Requirements

***Purge Requirements***

***IRU box***
***Science instruments***
***N******2****** boil-off (better than MIL-P-27401C Grade B, 2**********m absolute filtered)***
***MIT-LL provided purge cart (all three instruments)***
***Protects against accidental exposure to condensable hydrocarbons***

## Cleanliness Maintenance

***Cleanliness Maintenance***

***Spacecraft cleaned during I&T flow as work is performed***
***External requirements (Visibly Clean, Sensitive)***
*1.86% obscuration (particulate), 2 mg/ft**2** (molecular)*
***Current levels***
*< 1% obscuration, 1 mg/ft**2** molecular*
***Thorough inspection and cleaning performed at critical milestones***
***Prior to Bay closures, following re-integration activity***
***Before and after movement between facilities***
***Before thermal vacuum test***
***Before launch***
***Spacecraft double-bagged when not in cleanroom***

## Open Issues

***Open Issues***

***IRU Helium exposure risks with purge in place***
***Helium usage in GSFC Building 7 complex***
*Continuous monitoring in place via helium detector*
***Launch vehicle environment***
*Purge tubing changes at launch site*
***Issue solved by adding a purge to the IRU***
***Fluoroglide on Delta fairing separation rails***
***Provide a fairing which is not lubricated with Fluoroglide***
***Installation of a shield is also under consideration***