1. SDO Contamination Engineering Subsystem Mission PDR
Sharon Straka
SDO Contamination Engineer

2. Agenda Introduction Changes Since SCR Instrument Requirements
SDO Contamination Control Approach
Instrument and Spacecraft Compatibility
SDO Contamination Analyses
SDO Venting Concept
Contamination Peer Review Summary
Contamination Control During SDO I&T
SDO Contamination Risks
Schedule
Issues
Conclusion

3. Introduction SDO Driving Contamination Requirements based on:
Instrument contamination requirements
Contamination requirements (internal and external) to minimize performance degradation
Thermal control surface requirements
Spacecraft contamination requirements
Star tracker contamination requirements
Geosynchronous environmental concerns
Outgassing of materials
Venting and vent paths
Electrostatic return of molecular contaminants
Propulsion effluent from thruster firings
Polymerization effects
Solar Activity
Environments of transfer orbits

4. Changes since SCR
Elimination of SHARPP coronagraphs allowed observatory exterior particulate requirements to be relaxed
From IEST CC1246D Level 300 ( 0.02 Percent Area Coverage) to Level 450 (0.14 Percent Area Coverage)
Instrument interior molecular and particulate requirements still tight
Propulsion system changed from a monopropellant system to bi-propellant system
All thrusters on aft end of S/C
Molecular adsorbers changed from TRMM heritage design to SWIFT design

5. Instrument Contamination Requirements

6. Instrument Contamination Requirements

7. Instrument Contamination Requirements
Preliminary HMI Contamination Requirements1
Hardware Sub-System
Beginning of Life2
End Of Life3
Instrument Interior4
Particulate
Molecular
Front Window/Door Interior
300
(0.02 PAC)
100 Angstroms
N/A
CCD & Camera Head
Assembly
100
( PAC)
TBD
Optical Surfaces
Instrument Exterior Surfaces5
Front Window
CCD Radiator
500
(0.24 PAC)
750
(2.0 PAC)
300 Angstroms
Electronics Package6 Exterior
Instrument Exterior
Based on Allowable Throughput loss: 20% at 6000A wavelength
1All cleanliness levels per IEST-CC1246D 4All interior surfaces are enclosed during assembly of optics package
2BOL is defined as the surface cleanliness level at delivery to observatory I&T 5Instrument exterior surfaces driven by S/C requirements
3EOL is defined as end of the 5 year mission 6This category includes CEBs and HEB

8. SDO Contamination Control Approach
Instrument providers are responsible for determining the specific Contamination requirements to minimize performance degradation.
Driving contamination requirements derived from instrument performance/science requirements
GSFC is responsible for the overall contamination control program
Observatory cleanliness levels will be consistent with the instrument requirements.
Instrument requirements are derived from science performance
The hardware design provides for minimization of contamination to and from external sources before, during, and after launch, and for removal of pre-launch contamination.
In general, all hardware will be compatible with the most contamination-sensitive components.
Spacecraft to instrument and instrument cross-contamination will be controlled in accordance to the overall SDO Contamination Control Plan (CCP), the requirements in the MAR, and the requirements in the Spacecraft to Instrument ICDs.
Development of a Contamination Control Plan
AIA and HMI have preliminary Contamination Control Plan
Observatory CCP in configuration control process
EVE CCP currently being drafted
Established a Contamination Working Group
Representatives from all instruments and observatory
Monthly Working Group Meetings and Telecons

9. Instrument and Spacecraft Compatibility
Instrument and Spacecraft Subsystem Outgassing Certification Requirements
Verified during thermal vacuum bakeout or thermal vacuum testing
Requirement to be defined in SDO CCP
Measured with TQCM
Results shall be submitted to SDO project for approval
Data set to include TQCM data, temperature of hardware, shroud temperature, chamber pressure, chamber configuration, and cold finger data
Exterior Cleanliness Requirements
A maximum (not to exceed) exterior particulate and molecular cleanliness requirement is imposed upon the instruments and subsystems
Currently 450A (0.14 Percent Area Coverage particulate, 100 Angstroms molecular)
Verified upon delivery to spacecraft integration
Maintained throughout integration, test and launch site operations

10. Instrument and Spacecraft Compatibility
Venting
Instrument and spacecraft vent locations and paths are compatible with overall spacecraft configuration
Positioned to minimize contamination of other contamination sensitive surfaces
GSFC responsible for verifying the instrument and subsystem vents are in compliance
Verified using on-orbit molecular mass transport modeling
Thruster Impingement
Spacecraft is designed to minimize thruster effluent impingement on contamination sensitive surfaces
Verified using a mass transport model.
Thruster effluent impingement levels are defined in SDO CCP

11. SDO Contamination Analyses
As part of the SDO contamination approach, the space environment with respect to spacecraft geometry, observatory contamination requirements, and on-orbit operations needed to be understood. The following analyses were performed to evaluate the SDO on-orbit environment:
Thruster plume impingement analysis of bi-propellant thrusters
Monopropellant vs. Bi-propellant trade studies
Thruster placement trade studies
SDO on-orbit mass transport analyses (on-going)
Determines outgassing certification requirements for instruments and subsystems
Provides outgassing and electrostatic return predictions
SDO venting analyses
Spacecraft vent placement
Verification of Instrument/Subsystem vent locations
SDO depressurization analysis through spacecraft vent
Performed for Atlas V and Delta IV

12. Bipropellant Thruster Results
Due to locations, orientations of 22 newton ACS thrusters and local S/C geometry, no contamination issues observed
Backflow from 445 newton thruster estimated to deposit less than 69 Å on lower deck Ka-band transmitter radiators
Could be much less than 69 Å
Thruster effluent does impact instrument apertures

13. Results of On-Orbit Mass Transport Analyses
Sensitive Surfaces
Direct Flux
Electrostatic Return
Total Molecular
AIA
Apertures
0 Angstroms
4 Angstroms
CCD Radiators
550 – 580 Angstroms
346 Angstroms
896 – 926 Angstroms
CEB Radiators
140 – 2100 Angstroms
35 Angstroms
175 – 2135 Angstroms
EVE
MEGS-A filters
0.05 Angstroms
0.04 Angstroms
0.09 Angstroms
MEGS-B filters
0.02 Angstroms
1.1 Angstroms
1.12 Angstroms
SAM
0.3 Angstroms
0.32 Angstroms
ESP
Instrument Radiator
680 Angstroms
1026 Angstroms
Electronics Radiator
210 – Angstroms1
245 – Angstroms
HMI
Aperture
3 Angstroms
40 Angstroms
43 Angstroms
340 – 390 Angstroms
686 – 736 Angstroms2
140 – Angstroms1
175 – Angstroms2
Star Tracker - Interior
1Highly dependent on surfaces facing S/A panels 2Currently exceeds HMI instrument requirements

14. SDO Venting Design
Venting design developed to control on-orbit outgassing and reduce the number/duration of spacecraft box bakeouts
2 vents located on the lower deck of the propulsion module
2 vents on +/- Y instrument module
Spacecraft volume and Instrument module volumes are separate
The spacecraft bus and propulsion module will be closed out to avoid unintentional venting in other directions.
Sealed with a layer of Mylar or Kapton under thermal blankets
Access panels closed out with tape
Vent effluent will pass through a molecular adsorber with a high efficiency for adsorbing contaminants
Molecular adsorbing Zeolite coating on filter
Adsorber Heritage
TRMM, SWIFT

15. S/C Vent Placement
Vents located on the Propulsion Module (PM) Lower Deck
Provides vent path for the entire S/C Bus and PM Volume
Analysis performed to size vents to achieve maximum 0.1 psid pressure differential requirement
PM Lower Deck
Vents

16. Contamination Peer Review Summary
Thruster Contamination Peer Review
Summary: Due to locations, thruster orientations, and S/C geometry, bi-propellant thrusters are not a contamination threat
August 8, 2003
4 Action Items, all closed
SDO PDR Contamination Peer Review
Major Findings:
Instruments need to define/mature beginning of life and end of life contamination requirements
Instrument requirements are drivers in the observatory contamination approach (technical, cost, and schedule)
Instruments need to develop verification techniques as soon as possible so that the SDO project can assess implications
Witness sample adequacy needs defended
Post I&T removal of instruments may be required
Contamination Control Plans and Contamination ICDs need signed off
February 24, 2004
27 action items/ 0 closed

17. Contamination Control during SDO I&T
Instruments
Before delivery to GSFC, the instruments shall undergo thermal vacuum bakeout and outgassing certification
Upon delivery to GSFC, the instruments exteriors will be certified to be Level 450A
inspected to visibly clean - highly sensitive using black and white light
Tape lifts taken where appropriate
Swab sample or wash performed where appropriate
Instrument providers are responsible for cleaning their instrument during I&T activities
GSFC will inspect instruments frequently using black and white light, tape lifts, molecular washes, and/or swab samples
Instruments will remain covered/bagged unless I&T activities require access
will be bagged at all times outside cleanroom
Exception: thermal vacuum testing
Instruments will be continually purged
Minimal purge interruptions may be required for some I&T activities
T-0 purge required at launch site
Purge system to be designed prior to CDR

18. Contamination Control during SDO I&T
Spacecraft/Observatory
SDO will be integrated in the Building 29 Spacecraft Systems Development and Integration Facility (SSDIF) or the Building 7 Spacecraft Checkout and Integration Area (SCA)
SSDIF :Class 1000 horizontal laminar flow cleanroom
SCA: Class 10,000 horizontal laminar flow cleanroom
Flight components/subsystems will be cleaned and inspected to required cleanliness levels before becoming inaccessible
All boxes/components cleaned and baked-out to required levels before delivery to I&T
All exterior components/subsystem inspected to Level 450A
All interior boxes/components inspected to 450A(TBD)
Spacecraft/Observatory will be covered/bagged during periods of inactivity
Frequent contamination inspections with contingency cleanings
SDO will be bagged during transportation between test facilities
Contamination levels measured using a combination of the following techniques as applicable: particle counters, NVR witness plates, BRDF measurements, real time NVR monitor, fallout plates, and tapelift samples

19. SDO Contamination Risks (Risk #3)

20. Contamination Schedule
Subsystem & Element
CY 2003
CY 2004
CY 2005
CY 2006
CY 2007
CY 2008 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
4/8
8/03
3/04
5/04
2/05
MISSION MILESTONES
LAUNCH
SRR/
SCR
ICR
PDR CR
CDR
PER
PSR
Contamination
2/24/04
11/04
PDR
CDR
Molecular Adsorber
Design
Fab
Test
Available to I&T
Replacement at Launch Site
1 = Spacecraft Integration
= Schedule Reserve
2 = Instrument Integration
3 = Environmental Testing
4 = Launch Site Operations
Spacecraft I&T 1 2 3 4
Launch

21. Issues Instrument contamination requirements need to be defined
Instrument requirements are drivers in the observatory contamination control approach (technical, cost, and schedule)
Instruments need to develop verification techniques as soon as possible and present approach to the SDO project
Witness sample adequacy needs defended
Post I&T removal of instruments for calibration may be required
Possible Technical, cost and schedule impacts

22. Conclusion
Internal instrument contamination requirements are challenging
Instruments are protected during observatory I&T
Removal of the coronagraphs allowed external particulate requirements to be relaxed
Plans are in place to meet the requirements
Instrument requirements are flowing down to subsystem design
Captured in Subsystem Contamination Matrix
Ready to proceed

23. Back-up Materials

24. Contamination Control Backup Slides

25. Contamination Control Backup Slides

26. Contamination Control Backup Slides

27. Contamination Control Backup Slides

28. Contamination Control during SDO I&T
Mass Properties
Test to be performed in the SSDIF
Class 1000 environment
EMI/EMC Test
Test will be performed in the RFI room of the SCA
Class 10,000 cleanroom
Vibration Test
Clean and operate the vibration cell as a cleanroom
Instruments to remained bagged and purged
Observatory to remain bagged/covered with bagging film
Acoustic Facility
Can be operated as Class 100,000 cleanroom after loading doors are closed
has separate gowning area
Instruments to remain bagged and purged
Spacecraft to remain bagged/covered with bagging film

29. Contamination Control during SDO I&T
Thermal Vacuum Test
SES chamber will be used
Vertical-load, cryopumped chamber
equipped with HEPA filtered air in the chamber and gowning room
Instruments to remain bagged and purged until just before pumpdown
After thermal cycling, the observatory outgassing rate will be certified
6 TQCMs will be used to monitor outgassing in TBD locations
Cold finger, Scavenger plates, witness samples, and fallout wafers will be utilized