Rev.
01
A
ECO
37-257
37-342
Description
Initial draft for comment
Updates based on feedback from
Instrument team
Author
ZKhan
ZKhan
Approved
RFGoeke
Date
6/5/2015
01/11/2016
TESS
Instrument Contamination Control Implementation Plan
Dwg. No. 37-15041
Revision A
November 2, 2015
37-15041
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Revision A
Table of Contents
1.0
1.1
Purpose ................................................................................................................ 1
Scope .......................................................................................................................... 1
2.0
List of Acronyms ................................................................................................. 1
3.0
Definitions ............................................................................................................ 2
4.0
Applicable and Reference Documents .............................................................. 3
5.0
Contamination Control Budget .......................................................................... 4
6.0
Contamination Control Measures ...................................................................... 5
7.0
Monitoring Cleanroom Environments ............................................................... 6
7.1
7.2
8.0
8.1
8.2
9.0
Non-volatile Residue (NVR) Monitoring ................................................................... 6
Particle Monitoring .................................................................................................... 6
Maintenance of Cleanroom Environments ........................................................ 6
Cleaning Procedure ................................................................................................... 6
Cleaning Schedule ..................................................................................................... 7
Monitoring of Flight Hardware Cleanliness ....................................................... 7
9.1
Light Inspections ....................................................................................................... 7
10.0
Bakeout of Flight Components to Limit Outgassing On-orbit ..................... 9
11.0
Maintenance of Flight Component Cleanliness............................................. 9
12.0
Monitoring of GSE Cleanliness ....................................................................... 9
13.0
Bakeout of GSE to Limit Outgassing in Clean Area .................................... 10
14.0
Maintenance of GSE Cleanliness.................................................................. 10
15.0
Use of Contamination Control Heaters during TVAC testing ..................... 10
16.0
Handling of Flight Hardware during Shipping and Transportation ........... 10
17.0
Handling of Flight Hardware during Testing................................................ 10
18.0
Instrument Purge ........................................................................................... 11
19.0
Material Control .............................................................................................. 11
20.0
Training ........................................................................................................... 11
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List of TBDs and TBRs
Section
Description of TBD/TBR
10.0
Documents describing bakeout procedures are TBD.
11.0
Document describing process for cleaning bag and box encasings of flight
components is TBD.
13.0, 14.0
Document describing procedure for the bakeout of the Dragon chamber is TBD.
15.0
TVAC tests using contamination control heaters are TBD.
16.0
Pack and shipping plans for components and assemblies others than CCDs,
and lens and camera assemblies are TBD.
17.0
Flight hardware handling procedures are TBD.
18.0
Document describing purge system is TBD.
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Revision A
Preface
This is the TESS Instrument Contamination Control Implementation Plan. It describes the
instrument contamination budget and the processes for monitoring and verifying instrument
cleanliness.
Revision 01 is the initial draft for comments.
Revision A is an update based on comments from the instrument team. Several sections were
added and others removed for the first release for configuration control.
37-15041
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1.0 Purpose
The purpose of this document is to describe the TESS instrument contamination budget,
contamination control measures and the processes for monitoring and verifying
instrument cleanliness to meet the contamination requirements laid out in the TESS
Instrument Contamination Control Plan (Document number 37-15040)
1.1 Scope
The implementation of contamination control for the TESS instrument is addressed for
the following phases till delivery of the instrument to Orbital ATK: fabrication, assembly,
and instrument integration and testing. The TESS instrument will undergo processing at
various locations including MIT Kavli Institute for Astrophysics and Space Research
(MKI) building NE83 and MIT Lincoln Lab (LL). This document covers instrument
contamination control implementation at both these facilities. Any contamination control
at vendor and subcontractor facilities will be described in vendor and subcontractor
documents.
2.0 List of Acronyms
AI&T
CCD
CCE
CCM
CCP
CVCM
DHU
ESD
FED-STD
FPA
GSE
GSFC
HEPA
IPA
I&T
LL
LPM
MIL-STD
MIT
MKI
37-15041
Assembly, Integration and Test
Charge Coupled Device
Contamination Control Engineer
Contamination Control Manager
Contamination Control Plan
Collected Volatile Condensable Materials
Data Handling Unit
Electrostatic Discharge
Federal Standard
Focal Plane Array
Ground Support Equipment
Goddard Space Flight Center
High Efficiency Particulate Air
Isopropyl Alcohol
Integration and Test
Lincoln Lab
Liters per minute
Military Standard
Massachusetts Institute of Technology
MIT Kavli Institute for Astrophysics and Space Research
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MLI
NASA
NVR
PAR
QA
QCM
RRU
TBD
TBR
TESS
TML
TQCM
TVAC
VC
VCS
Multi-Layer Insulation
National Aeronautics and Space Agency
Non-Volatile Residue
Performance Assurance Requirements (Document)
Quality Assurance
Quartz Crystal Microbalance
Risk Reduction Unit
To Be Determined
To Be Reviewed
Transiting Exoplanet Survey Satellite
Total Mass Loss
Temperature-Controlled Quartz Crystal Microbalance
Thermal Vacuum
Visibly Clean
Visibly Clean Sensitive
3.0 Definitions
Cleanroom
Room in which the concentration of airborne particles is
controlled to specified limits.
Clean Zone
Defined space in which the concentration of airborne particles
is controlled to specified limits. Clean zones are classified in
accordance with ISO-14644, which describes the maximum
number of particles permitted per cubic foot of air.
Contamination Any unwanted material that causes degradation in the desired
function of an instrument or flight hardware.
Contamination Organized action to control the level of contamination.
Control
Fiber
A particle whose length-to-width ratio exceeds 10:1 with a
minimum length of 100 microns.
Gross
Cleaning hardware surfaces to visual inspection standards
Cleaning
Level x per
The cleanliness level defined by a number and/or letter
MIL-STD
designating the particle distribution and molecular cleanliness,
1246
respectively.
Nitrogen
Pressurized flow of clean, dry nitrogen through a system in
Purge
order to displace impurities and reactive species.
Non-Volatile
Soluble material remaining after evaporation of a volatile liquid
Residue
which usually causes degradation in the desired function of an
instrument or flight hardware.
Particle
A small quantity of solid or liquid material with definable shape
or mass with a length to width ratio less than 10:1.
Particle Size
Expressed as the apparent maximum linear dimension or
diameter of the particle.
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Precision
Cleaning
Sensitive
Surface
Solvent
Flushing
Solvent
Washes
Surface
Cleanliness
Level
Swab Sample
Vapor
Degrease
Visibly Clean
A cleaning procedure done in a controlled environment to attain
a specific level of cleanliness. This procedure follows gross
cleaning.
Any surface of flight hardware that must meet a specified
cleanliness level to ensure the minimum performance levels.
Method of cleaning surfaces with a stream of filtered solvent
under pressure, which is directed against a surface to dislodge
and rinse away any foreign material.
A quantitative method of verifying MIL-STD-1246 molecular
cleanliness levels by measuring molecular contamination in a
solvent, which was washed over a surface and collected.
An established level of maximum allowable particulate and/or
NVR contamination ranging from visibly clean to specific MILSTD-1246 levels (e.g., Level 300A, Level 300B, etc.).
A qualitative method of identifying contaminants by analyzing
the residue on a solvent-soaked swab that was wiped over a
surface.
Item to be cleaned is exposed to heated solvent vapors that
condense on the part and wash away contaminant.
The achievement of a clean surface as seen without optical
aids (except corrected vision) as measured by a specified
method. Three levels of visibly clean (VC) requirements are
defined in SN-C-0005D
4.0 Applicable and Reference Documents
The applicable and reference documents mentioned in this TESS Instrument
Contamination Control Implementation Plan are listed in Table 1 and Table 2.
Table 1 - Applicable TESS Documents
Document Number
37-10037
37-15040
37-15030.01
37-15030.02
37-65010
Document Title
TESS Contamination Control Plan
TESS Instrument Contamination Control Plan
TESS Pack and Shipping Plan for CCDs
TESS Pack and Shipping Plan for Lens and Camera
Assemblies
TESS Pup and Pony Certification Procedure
Table 2 - Contamination Control Reference Documents
Document Number
MIL-STD-1246
JSC SP-R-022A
37-15041
Document Title
Product Cleanliness Levels and Contamination
Control Program
Specification Vacuum Stability Requirements of
Polymeric Materials for Spacecraft Applications
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ASTM E595
IEST-RP-CC018.4
ISO-14644-8
FED-STD-209
SN-C-0005D
JPG 5322.1 Rev. E
PS-3-21
ASTM E235-8
ASTM E1234-07
PS-3-27
Standard Test Method for Total Mass Loss and
Collected Volatile Condensable Materials from
Outgassing in a Vacuum Environment
Cleanroom Housekeeping – Operating and Monitoring
Procedures
Cleanrooms and Associated Controlled Environments
Airborne Particulate Cleanliness Classes in
Cleanrooms and Clean Zones
Contamination Control Requirements for the Space
Shuttle Program (NASA)
Contamination Control Requirements Manual (NASA)
Precision Cleaning [MIT Lincoln Lab document]
Standard Test Method for Gravimetric Determination
of Nonvolatile Residue (NVR) in Environmentally
Controlled Areas for Spacecraft
Standard Practice for Handling, Transporting, and
Installing Nonvolatile Residue (NVR) Sample Plates
Used in Environmentally Controlled Areas of
Spacecraft
Implementation of Contamination Control
Requirements [MIT Lincoln Lab document]
A. C. Tribble, Fundamentals of Contamination
Control. Bellingham, Wash: SPIE Optical Engineering
Press, 2000.
MIL-PRF-27401F
Performance Specification: Propellant Pressurizing
Agent, Nitrogen
5.0 Contamination Control Budget
A flow chart of the assembly, integration and test (AI&T) process, developed by the
Instrument I&T Manager, is used to elucidate the cleanliness environment and
contamination control actions during each step of AI&T and captured in a table. This is
the basis of maintaining a contamination budget to achieve the requirements set forth in
the TESS Instrument Contamination Control Plan (37-15040). Since the AI&T flow
development is ongoing, a complete flowchart and associated table is out of scope of
this document. However, Figure 1 shows an example of one part of the AI&T process.
The table used to capture the contamination budget associated with this flow has the
following headings: Step ID, Step Name, Location, Environment (i.e. cleanroom class),
Exposure Time
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The methods used to achieve contamination control during AI&T are detailed in the
following sections.
Figure 1 - Example AI&T Flow
The contamination budget will be maintained by the Contamination Control Lead at MKI.
6.0 Contamination Control Measures
To achieve the contamination control requirements, the following measures will be used.
Details for these measures are provided in the following sections.

Monitoring clean room environments

Maintenance of clean room environments

Monitoring of flight hardware cleanliness

Bakeout of flight components to limit outgassing on-orbit.

Maintenance of flight component cleanliness

Monitoring of GSE hardware cleanliness

Bakeout of GSE to limit outgassing on-orbit in clean room

Maintenance of GSE cleanliness

Use of contamination control heaters during thermal vacuum (TVAC) testing

Proper handling of flight hardware during shipping and transportation

Proper handling of flight hardware during testing

Instrument purge

Material control
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
Training
7.0 Monitoring Cleanroom Environments
7.1 Non-volatile Residue (NVR) Monitoring
NVR is monitored in the clean work area where devices are built by using witness plates.
An outside analytical laboratory, similar to Balazs Analytical Services is used to provide
pre-measured witness plates (silicon wafers) to be placed in the work area, where
devices are assembled. The witness platess are exposed to the clean room environment
and are then returned for the NVR analysis to the laboratory. This method is used both
at Lincoln Lab and the MIT Kavli Institute (NE83). Lincoln Lab witness plates are
analyzed every 3 months and NE83 witness plates are analyzed every month or as
determined by the Instrument Contamination Control Lead. In case the NVR level does
not meet the cleanliness requirements, Mission Assurance shall be notified.
7.2 Particle Monitoring
Particles in the Lincoln Lab Clean Rooms used for TESS are continuously measured by
particle counter, LASAIR II 310A manufactured by Particle Measuring Systems or
equivalent. These clean rooms are maintained at Class 1000 (FED-STD-209). The work
benches in these clean rooms are laminar flow type maintaining a cleanliness level of
Class 100. Particles in the MKI Clean Tents in NE83 are monitored by the following
particle counters: HandiLaz Mini manufactured by Particle Measuring Systems and Met
One 273 A-B by Beckman Coulter or equivalent. These clean tents are maintained at
Class 1000 (FED-STD-209) with laminar flow workbenches maintaining a cleanliness
level of Class 100. NE83 clean tents are monitored for particulates twice a day on
weekdays or as determined by the Instrument Contamination Control Lead. In case the
particulate level on the witness plate does not meet the cleanliness requirements, the
hardware shall be cleaned to bring it in compliance and Mission Assurance shall be
notified.
8.0 Maintenance of Cleanroom Environments
Cleanroom environments will be maintained through cleaning as described in the
following subsections and through observing gowning processes outlined in Mission
Assurance documents.
8.1 Cleaning Procedure
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Clean tents are cleaned in accordance with MIT Lincoln Lab procedure # PS-3-21
8.2 Cleaning Schedule
The cleaning schedule for the clean tents is bi-monthly at a minimum with more intervals
added as needed determined by Instrument Contamination Control Lead.
9.0 Monitoring of Flight Hardware Cleanliness
To verify the requirements laid out in the TESS Instrument Contamination Control Plan
(37-15040) and to verify effectiveness of contamination control measures, the
cleanliness of components will be monitored in various ways.
A. In general, components will be subject to a light inspection (described in Section
9.1) to verify particulate cleanliness at the following events:
1. Upon receipt from another facility
2. Before shipping to another facility
3. Before the start of a test
4. After the end of a test
5. As needed
The results of these inspections will be logged on Snebulos.
B. The NVR cleanliness levels for optical components will be calculated for each
AI&T step using the NVR deposition rates at the facility, measured with methods
defined in Section 7.1 and the exposure times of the components during the step.
The optical components will be assumed to have zero NVR deposition at the
start of assembly, integration and test (AI&T) processing at MIT Lincoln Lab and
MIT Kavli Institute (NE83) i.e. they will be assumed to arrive completely clean
from the manufacturer. During each step of AI&T, the environmental conditions
and exposure time of the components will be logged.
C. Optionally, witness plates will follow the CCDs and instrument cameras during
AI&T to log cumulative NVR contamination levels. These will be analyzed as
needed, determined by the Contamination Control Leads at LL and MKI.
9.1 Light Inspections
Visual inspection is done using black (UV) light or white light. The requirements of the
Visually Clean Levels (VC-I to VC-IV) are given in Table 3. Visibly clean, using white
light is the absence of all particulates and non-particulates visible to normal unaided eye
(except corrected vision). The white light used will be >100 ft-candles. UV inspection
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light source will be >3000 ft-candles and during inspection should not be more than 18
inch from the inspected item. During UV inspection light from other sources should not
be more than 5 ft-candles. If visual contamination is present, the hardware must be
cleaned and then re-inspected under the same light conditions. If during UV inspection
there is any evidence of fluorescence (presence of an organic contaminant) the item or
surface must be re-cleaned. If re-cleaning does not reduce the fluorescence, it will be
determined whether the fluorescing material is a contaminant or the substrate surface.
Inspections for verifying cleanliness Levels 500 to 1000 (per MIL-STD-1246C), or VC-I
and VC-II, the above inspection method is adequate. Inspection for Levels 200 to 300
(per MIL-STD-1246C) should be conducted using a 3X magnifier in addition to the white
and UV light sources. For the verification of Levels 50 to 100 (per MIL-STD-1246C) a
10X magnifier is required.
As an example, once a surface is inspected with a 3X magnifier using the white light and
UV light, and all the particles visible (~ 10 to 15 microns and larger) are removed, the
surface will meet the cleanliness Level 200 (per MIL-STD-1246C) requirements.
All light inspections must be performed by trained personnel.
Table 3 - Visually Clean Levels [Ref: A. C. Tribble, Fundamentals of Contamination Control.
Bellingham, Wash: SPIE Optical Engineering Press, 2000.]
Level
Illumination
(ft -candles)
Inspection
Distance
Magnification
UV
Light
Resolution
Limit (µm)
Standard
VC-I
50
5-10 ft
1
no
600-1200
Sensitive
VC-I1/2
50
2-4 ft
1
no
240-480
Highly Sensitive
VC-II
100
6-18 in
1
no
60-180
Highly Sensitive
VC-III
100-200
6-18 in
1
no
10-90
Highly Sensitive
VC-IV
100-200
6-18 in
2-7
yes
~10
Notes
37-15041
(1)
One-foot candle (lumens per square foot) is equivalent to 10.76 lumens per
square meter.
(2)
Cleaning is required if the surface in question does not meet VC under the
specified incident light and observation distance conditions.
(3)
Exposed and accessible surfaces only.
(4)
Initial cleaning is mandatory; Note (2) applies thereafter.
(5)
Areas of suspected contamination may be examined at distances closure than
specified for final verification.
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(6)
The notes which apply to each VC levels are:
Standard:
(2) (3) (5)
Sensitive:
(2) (3) (5)
Highly Sensitive:
(3) (4)
10.0 Bakeout of Flight Components to Limit Outgassing Onorbit
The DHU will be baked out at the vendor facility.
The following documents describe bakeout procedures for components that are being
baked out at LL: TBD
The following documents describe bakeout procedures for components that are being
baked out at MKI: TBD
11.0 Maintenance of Flight Component Cleanliness
Flight components will be cleaned as needed including if the contamination levels on the
hardware exceed the cleanliness requirements, a cleaning will be scheduled. The
cleanings will be performed by the trained and qualified technicians following the
process outlined in the Lincoln Laboratory Process Specification PS-3-21.
Bag and box encasings of flight components will also be cleaned. These cleanings will
be performed by the trained and qualified technicians following the process outlined in
TBD document.
12.0 Monitoring of GSE Cleanliness
Cleanliness of GSE at LL facilities will be monitored using MIT Lincoln Lab procedure #
PS-3-21
Cleanliness of GSE in clean areas at NE83 will be monitored through particulate light
inspections as described in Section 9.1. The monitoring frequency will be set by the
Contamination Control Leads at MKI and LL and the Instrument I&T Manager.
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13.0 Bakeout of GSE to Limit Outgassing in Clean Area
The Pup, Pony and Dragon TVAC GSE in NE83 needs to be baked out to limit
outgassing and contaminating flight hardware in the clean areas.
The procedure for the bakeout of the Pup and Pony chambers is described in TESS Pup
and Pony Certification Procedure [document number 37-65010]
The procedure for the bakeout of the Dragon chamber is TBD.
14.0 Maintenance of GSE Cleanliness
Cleanliness of GSE at LL facilities will be maintained using standard LL procedures.
At NE83, if inspections show Pup and Pony GSE exceeding particulate cleanliness
requirements, it will be recleaned as described in TESS Pup and Pony Certification
Procedure [document number 37-65010]. The cleaning procedure for Dragon GSE is
TBD.
15.0 Use of Contamination Control Heaters during TVAC testing
Kapton heaters integrated into the camera design will be used during certain TVAC tests
[test numbers TBD] to prevent contamination buildup on cold lens surfaces as the
chamber is brought back to room temperature.
16.0 Handling of Flight Hardware during Shipping and
Transportation
MKI will handle packing and shipping of CCDs as outlined in the TESS Pack and
Shipping Plan for CCDs [document number 37-15030.02].
Lens and camera assemblies will be handled as outlined in the TESS Pack and Shipping
Plan for Lens and Camera Assemblies [document number 37-15030.01].
Pack and shipping plans for other components and assemblies are TBD.
17.0 Handling of Flight Hardware during Testing
Flight hardware will be handled using the following procedures: TBD
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18.0 Instrument Purge
The instrument is equipped with a nitrogen purge system to purge all four cameras
during AI&T phases when the cameras are mounted to the camera plate and during
launch processing. The purge system details are described in TBD document.
It consists of a purge manifold on the camera plate which supplies nitrogen to all four
cameras through purge inlets. There are purge vents located on each camera.
The primary purpose is to provide a dry nitrogen environment to CCDs during AI&T and
launch processing.
Nitrogen is supplied to the purge manifold at 5.7 liters per minute (LPM) using a purge
suitcase supplied by the Instrument team. The purge suitcase needs to be connected to
a nitrogen source supplying Grade B Type 1 (per MIL-PRF-27401F).
19.0 Material Control
TESS hardware will be subject to material control as outlined in Mission Assurance
documents.
20.0 Training
TESS personnel working in clean areas and handling flight hardware will be trained as
outlined in Mission Assurance documents.
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