11602_rA
Release Date: 14 June 2015
Title: TESS Instrument Camera L4 Requirements
Revision A
TESS Instrument Camera
Level 4 Requirements
June 14, 2015
Revision A
Lincoln Laboratory
Massachusetts Institute of Technology
Lexington, Massachusetts
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Document 37-11602
Rev A
Document No: 37-11602
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Release Date: 14 June 2015
Title: TESS Instrument Camera L4 Requirements Rev A
R EVISION H ISTORY
Version ECO
01q
A
Description
Pre-PDR release
37-262
Pre-CDR release.
Updated formatting throughout.
Implemented requirements changes based on changes in IRD, ARD, MRD, ERD, EICD and MICD.
Deleted L4_CAM_06, L4_CAM_11, L4_CAM_13,
L4_CAM_21, L4_CAM_26, L4_CAM_21,
L4_CAM_32 through L4_CAM_38, L4_CAM_41,
L4_CAM_42, L4_CAM_54
Document 37-11602
Date Initiator
8/20/2014 K. Clark
6/14/2015 T. Roy
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Document 37-11602
Table of Contents
Instrument Requirements Verification Methods ................................................... 7
L4_CAM_01 Volume - Camera ................................................................. 8
L4_CAM_02 Mass - Camera ...................................................................... 8
L4_CAM_03 Power – Camera ................................................................... 8
L4_CAM_26 Total Power - Camera........................................................... 9
L4_CAM_40 Survival Power - Camera ..................................................... 9
L4_CAM_04 Camera Boresight - Camera ................................................. 9
Data and Command Requirements ............................................................. 9
L4_CAM_45 Camera Image Data .............................................................. 9
L4_CAM_06 Full Frame Images - Camera .............................................. 10
L4_CAM_41 Quaternion Stability - Camera ............................................ 10
L4_CAM_42 Quaternion Accuracy – Camera ......................................... 10
L4_CAM_43 Camera Housekeeping Data ............................................... 10
L4_CAM_44 Camera Command .............................................................. 10
L4_CAM_55 Systematic Timing Precision - Camera .............................. 10
L4_CAM_08 FOV - Camera .................................................................... 11
L4_CAM_23 Camera Boresight Alignment ............................................. 11
L4_CAM_09 Effective Area - Camera ..................................................... 11
L4_CAM_54 Systematic Error - Camera CCD Gain ............................... 12
L4_CAM_10 Photometric Error: Temperature Effects ............................ 12
L4_CAM_48 Change in CCD Gain - Camera .......................................... 12
L4_CAM_49 Change in CCD QE – Camera ............................................ 12
L4_CAM_11 Distortion Induced Image Motion - Camera ...................... 12
L4_CAM_46 Systematic Error: Periodic Error Residual - Camera ......... 12
L4_CAM_05 BPFF - Camera ................................................................... 13
L4_CAM_28 Readout Noise - Camera ..................................................... 13
L4_CAM_12 Stray Light - Camera .......................................................... 13
L4_CAM_51 Instrument Return to Science - Camera ............................. 13
Robustness and Safety Requirements ....................................................... 13
L4_CAM_13 Fault Containment-Camera ................................................ 13
L4_CAM_52 Hazard Mitigation – Camera .............................................. 14
L4_CAM_14 Power Shutdown – Camera ................................................ 14
L4_CAM_15 SEU – Camera .................................................................... 14
L4_CAM_16 Sun Pointing ....................................................................... 14
L4_CAM_47 Camera Life ........................................................................ 14
L4_CAM_17 Environment – Camera ....................................................... 15
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L4_CAM_25 Camera Temperature - Lens ............................................... 15
L4_CAM_31 Lens Temperature Variation ............................................... 15
L4_CAM_18 CCD Temperature .............................................................. 15
L4_CAM_26 Power Dissipation............................................................... 16
L4_CAM_19 MTICD and MICD - Camera ............................................. 16
L4_CAM_20 EICD - Camera ................................................................... 16
L4_CAM_53 CAM-DHU ICD – Camera................................................. 16
L4_CAM_21 CRF – Camera .................................................................... 16
L4_CAM_22 External Optical Surface – Contamination Control ........... 17
L4_CAM_29 CCD - Contamination Control ........................................... 17
L4_CAM_30 Internal Optical Surfaces -Contamination Control ............. 17
L4_CAM_27 Purge Ports - Camera .......................................................... 17
L4_CAM_32 ERD 3.1.1.1 Limit Loads - Camera.................................... 18
L4_CAM_33 ERD 3.1.3 Sine Vibration - Camera ................................... 18
L4_CAM_34 ERD 3.1.4 Random Vibration - Camera ............................ 18
L4_CAM_35 ERD 3.1.5 Shock - Camera ................................................ 18
L4_CAM_36 ERD 3.1.7 Ambient Pressure -Camera ............................... 18
L4_CAM_37 ERD 3.1.9 Humidity - Camera ........................................... 18
L4_CAM_38 ERD 3.1.8.2 Temperature Performance Requirements – Camera
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1.0
PREFACE
This is the Transitioning Exoplanet Survey Satellite (TESS) Instrument Requirements Document.
It contains Level 4 Instrument requirements including verification methods. Requirements in this document are responsive to Level 3 requirements contained in the Instrument Requirement s Document
(IRD).
Revision 01 was an initial pre-PDR draft for comment based on the initial IRD release.
Revision A is a pre-CDR release to incorporate changes in IRD, ARD, MRD, ERD, EICD and MICD.
2.0
LIST OF TBDS AND TBRS
ID Title Requirements
3.0
INTRODUCTION
TESS Instrument (INS) requirements are at Level 3 and are flowed down to four sets of Level 4 requirements, each of which corresponds to an INS subsystem: the Camera (CAM), the Camera Plate
Assembly (CPA), the Harness (HAR) and the Data Handling Unit (DHU). The TESS Instrument includes four Cameras: requirements included herein shall refer to a single Camera unless otherwise specified.
The Camera is comprised of four lower level (Level 5) assemblies: the Detector Assembly (DET), Lens
Assembly (LEN), Lens Hood (HOD) and Camera Flexures (FLX).
This document presents the TESS Instrument Camera Level 4 requirements. These requirements are flowed down from TESS Level 3 requirements from the TESS Instrument Requirements Document
(IRD). All relevant documents referenced in the Camera Level 4 requirements are listed in Section 4.
Section 5 lists certain definitions used in the requirements and Section 6 contains a general description of the verification methods for the Camera Level 4 requirements. The full text of Level 4 requirements, associated rationale, parent requirements, verification methods and allocations is provided in Section 7.
A list of abbreviations and acronyms used in this document is provided in Section 8.
4.0
RELEVANT DOCUMENTS
This document articulates requirements flowed down from the Level 3 requirements and other sources listed below. Any reference to the sources below implies use of the revision specified in the
Source Dwg. # column. For example, any reference of the Mission Requirements Document will refer to the acronym, MRD, and assume Rev C only – no previous or subsequent versions unless otherwise
specified. The documents listed here are applicable to the extent specified herein. Unless otherwise stipulated, the most recently approved version of a listed document shall be used. Reference documents below contain supplemental information to guide the user in the application of this document.
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Ref.
1
Document Name
Document 37-11602
Source Dwg #
Instrument Dwg
#
37-11601, Rev C 37-11601
Designation
Applicable
2
3
TESS Instrument Requirements
Document (IRD)
TESS Mission Requirements Document
(MRD)
TESS Environmental Requirements
Document (ERD)
EXP-TESS-GSFC-
RQMT-0001, Rev C
EXP-TESS-GSFC-
RQMT-0002, Rev
D
6150232000R1,
Rev B
37-10003
37-10020
37-12001.02
Applicable
Applicable
Applicable 4
5
6
Spacecraft-Instrument Mechanical and
Thermal Interface Control Document
(MTICD)
Spacecraft –Instrument Mechanical
Interface Control Drawing (MICD)
Spacecraft-Instrument Electrical
Interface Control Document (EICD)
7
8
Camera – DHU Electrical Interface
Control Document (CAM-DHU ICD)
Instrument Harness Interface Control
Document (Harness ICD)
9 Camera Plate Assembly Drawing (MIT-
LL)
10 Military Standard Product Cleanliness
Levels and Contamination Control Plan
11 JSC Space Shuttle Contamination
Control Requirements
12 Instrument Flight Operational Software
Data Dictionary
13 TESS Instrument Preliminary Hazard
Analysis
14 TESS Instrument FMEA/FMECA, Critical
Item List and Single Point Failure List
Document
15 TESS Instrument FMEA Report
16 TESS Contamination Control Plan
6150410000R0,
Rev A
6150232000R0,
Rev B
37-12001.0201 Applicable
37-12001.01
37-12050, Rev A 37-12050
Applicable
Applicable
37-12051
821112
MIL-STD-1246C
SN-C-005, Rev D n/a
37-52002, Rev A 37-52002
37-11004.08, Rev
B
37-11004.21, Rev
A
37-12051
821112 n/a
37-11004.08
37-11004.21
Applicable
Applicable
Reference
Reference
Reference
Reference
Reference
37-11004.2101
EXP-TESS-GSFC-
37-11004.2101
37-10037
PLAN-0037, Rev-
37-15040, Rev A 37-15040
Reference
Applicable
Applicable 17 TESS Instrument Contamination
Control Plan
18 TESS Instrument Verification &
Validation Plan
19 Table of Acronyms (Section 8)
37-15001, Rev 03 37-15001 n/a n/a
Applicable
Reference
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5.0
DEFINITIONS
Document 37-11602
Term Definition
Science Postage Stamps Science Postage Stamps are one of the science data products generated by the TESS Instrument. They consist of time-integrated measurements from
CCD pixel subarrays are associated with TESS target stars.
Full-Frame Images
Science Data
Full-Frame Images are the time-integrated full CCD images from each
Instrument Camera.
Science Data generated by the Instrument is composed of Science Postage
Stamps and Full-Frame Images.
Instrument Data
Spacecraft Ancillary
Data
Data from the Instrument that is sent to the Ka-band transmitter to be sent to the ground is called the Instrument Data. It consists of: 1) Science
Data, 2) Instrument Housekeeping Data, and 3) Spacecraft Ancillary Data.
Spacecraft Ancillary Data consists of Spacecraft sensor data relevant to science processing. The Spacecraft Master Avionics Unit (MAU) periodically sends packets containing this data to the TESS Instrument
Quaternions
Data Handling Unit (DHU) for storage on the Instrument Solid State
Recorder, and eventual transmission over the Ka-band transmitter to the ground, along with the related science data.
Quaternions are data products generated by the DHU that are used by the
Spacecraft ACS software. Each Camera sends star field images to the DHU every 2 seconds (each Camera exposure is offset from the other every 0.5 seconds). The images are then converted into pointing error and sent to the MAU via a Fine Pointing Packet that includes the Camera ID from which the quaternion was generated as well as a measure of the quality of the quaternion (details are presented in the EICD).
6.0
INSTRUMENT REQUIREMENTS VERIFICATION METHODS
This section outlines the categories of verification methods for demonstrating that the TESS
Instrument meets the Level 4 requirements described in this document. For additional details, see TESS
Instrument Verification & Validation Plan (Dwg. # 37-15001). The verification methods are categorized as “inspection,” “test,” “demonstration,” and “analysis” and described below:
Description Verification
Method
Inspection:
Test:
This is used to determine system characteristics by examination of and comparison with engineering drawings or flow diagrams and computer program listings during product development to verify conformance with specified requirements.
Inspection is generally non-destructive and consists of visual examinations.
Inspection is also used to verify contamination control requirements using procedures specified in contamination standards.
Test is used to verify conformance of physical and functional characteristics with operational and technical requirements. The test process will generate data, and measurement equipment or procedures normally record these data. Analysis or review is subsequently performed on the data derived from the testing. Analysis as
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Verification
Method
Description
Document 37-11602 described here is an integral part of this method and should not be confused with the "analysis" described in the fourth verification category.
Demonstration: This is a variation of the test method used to verify conformance of functional characteristics with specified requirements by go/no-go criteria without the use of elaborate measurement equipment.
Analysis: Analysis or review of simulation data is a study method resulting in data used to verify conformance of characteristics with specified requirements. Worst-case data may be derived from design solutions where quantitative performance cannot be demonstrated cost-effectively.
7.0
L4 SUBSYSTEM REQUIREMENTS
7.1
Physical Requirements
7.1.1
L4_CAM_01 Volume - Camera
ID Number
Requirement
Rationale
L4_CAM_01 Volume - Camera
The dimensions of each Camera shall be contained by the envelope specified in the MTICD and MICD.
All four Cameras are part of the CSA (Camera Structure Assembly) and their dimensions are constrained by the Instrument design. The MTICD includes references from the MICD for volume constraints.
Parent(s) IRD_01 - The Instrument dimensions shall be contained by the envelope specified in the MTICD.
Verification Method Inspection, Analysis
Allocation
7.1.2
L4_CAM_02 Mass - Camera
ID Number L4_CAM_02 Mass - Camera
Requirement
Rationale
The sum of all four Cameras shall not exceed 59.5 kg.
Above-deck Instrument mass is limited per IRD_81. The allocation is driven by the need to accommodate CPA and HAR subsystems above-deck while meeting design criteria and accounting for margin.
Parent(s) IRD_81 - The CSA mass shall not exceed 82 kg. Contributions to CSA mass are identified in the MTICD.
IRD_02 - The total Instrument mass shall not exceed 92 kg.
Verification Method Test
Allocation
7.1.3
L4_CAM_03 Power – Camera
ID Number
Requirement
Rationale
L4_CAM_03 Power - Camera
The focal plane electronics (FPE) in each Camera shall have an operational power consumption (not including the offset heater) of no less than 4.7 and no greater than 8.1W.
Thermal model predicts focal plane electronics (FPE) must consume below 8.1W in order to keep the CCD temperature below -60ᴼC. If the FPE consumes less than
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Parent(s)
4.7W, the electronics will drop below the minimum operational range.
IRD_78 - The Instrument Cameras thermal power shall be no greater than 65W.
IRD_04 - The Instrument power consumption shall be no greater than 160 W.
Verification Method Test
Allocation DET
7.1.4
L4_CAM_26 Total Power - Camera
ID Number
Requirement
Rationale
Parent(s)
L4_CAM_26 Total Power- Camera
All four Cameras shall dissipate no more than 56W total power (FPE and Offset
Heater).
The purpose of the offset heater is to control the average temperature of the Lens
Assembly to be -75ᴼC. The amount of power dissipated by the offset heater is dependent in part on the power dissipated by the FPE operational power
(L4_CAM_03). The total power dissipated by the camera (a sum of the FPE operational power and offset heater) is limited by both the thermal design and power allocations from the Spacecraft. Note the 56W power limitation value includes expected converter losses in the DHU.
IRD_78 - The Instrument Cameras thermal power shall be no greater than 65W.
IRD_04 - The Instrument power consumption shall be no greater than 160 W.
Verification Method Test
Allocation DET
7.1.5
L4_CAM_40 Survival Power - Camera
ID Number
Requirement
Rationale
L4_CAM_40 Surival Power - Camera
Each Camera survival heater shall be sized to dissipate no more than 14W.
The MAU upper limit of survival power to the Instrument is 65W. Power-per-
Camera value includes expected converter losses.
Parent(s) IRD_62 - The Instrument survival electrical power consumption shall be no greater than 65 W.
Verification Method Inspection, Test
Allocation DET
7.1.6
L4_CAM_04 Camera Boresight - Camera
ID Number
Requirement
Rationale
L4_CAM_04 Camera Boresight - Camera
In each Camera, the optic axis of the lens assembly shall intersect the focal plane array within 1 mm of the center of the focal plane array active area.
The Camera internal alignment is necessary to achieve the desired brightest pixel flux fraction (BPFF). To a lesser degree, misalignment will reduce the effective transmission of the lens and as a result effetive area.
IRD_63 -The instrument shall achieve a total photometric precision, accounting for Parent(s) all statistical and systematic error sources other than stellar variability, to be less than 230 ppm for a K5V star at I=10 on a one hour timescale.
Verification Method Test, Inspection
Allocation LEN, DET
7.2
Data and Command Requirements
7.2.1
L4_CAM_45 Camera Image Data
ID Number
Requirement
L4_CAM_45 Camera Image Data
Each Camera shall generate and send the DHU image data every 2 seconds relative
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Rationale
Parent(s) to the synchronization pulse, per the CAM-DHU ICD.
The DHU receives images from each Camera every two seconds in order to process them for science data products as well as quaternions.
IRD_08 - The Instrument shall generate and store a series of continuous "Science
Postage Stamps", i.e. pixel subarrays centered on each target star specified in the
Target Star Table, with nominal integration times of no more than 120 seconds.
Verification Method Test
Allocation DET
7.2.2
L4_CAM_06 Full Frame Images - Camera
[Deleted]
7.2.3
L4_CAM_41 Quaternion Stability - Camera
[Deleted]
7.2.4
L4_CAM_42 Quaternion Accuracy – Camera
[Deleted]
7.2.5
L4_CAM_43 Camera Housekeeping Data
ID Number
Requirement
Rationale
L4_CAM_43 Instrument Housekeeping Data Generation - Camera
Each Camera shall generate and send housekeeping data to the DHU as specified in the CAM-DHU ICD.
Flowdown from IRD_14, IRD_15, IRD_56 and IRD_57. Camera must send housekeeping data to DHU as specified in CAM-DHU ICD.
Parent(s) IRD_14 - The Instrument shall generate and store Instrument housekeeping data.
IRD_15 - The Instrument shall send Instrument state-of-health (SOH) data, including hardware and software housekeeping data, to the spacecraft as defined in the Spacecraft-Instrument Electrical ICD.
IRD_56 - The Instrument shall monitor Instrument housekeeping data for onboard fault detection.
IRD_57 - The Instrument shall be capable of generating and sending diagnostic and commissioning data to the spacecraft as commanded.
Verification Method Test
Allocation DET
7.2.6
L4_CAM_44 Camera Command
ID Number
Requirement
L4_CAM_44 Camera Command
Each Camera shall be capable of receiving commands from the DHU as specified in
Rationale
Parent(s) the Camera-DHU ICD.
The DHU is responsible for controlling the Cameras to take images.
IRD_26 - The instrument Flight Software shall be modifiable on orbit.
Verification Method Test
Allocation DET
7.2.7
L4_CAM_55 Systematic Timing Precision - Camera
ID Number
Requirement
L4_CAM_55 Systematic Timing Precision - Camera
Each Camera shall limit the variability in the exposure time of the two-second camera exposures averaged over an hour to < 42 microseconds from one hour to the next relative to the time signal from the spacecraft.
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Rationale
Parent(s)
Flowdown from IRD_54 - allocation of 42 micro seconds is to the Camera (the remaining 42 micro-second allocation is to the DHU).
IRD_54 - The instrument shall limit the variability in the exposure time of the twosecond camera exposures averaged over an hour to < 84 microseconds from one hour to the next relative to the time signal from the spacecraft.
Verification Method Test
Allocation DET
7.3
Observing Requirements
7.3.1
L4_CAM_08 FOV - Camera
ID Number
Requirement
Rationale
Parent(s)
L4_CAM_08 FOV - Camera
Each Camera field-of-view (FOV) shall be 24 ±0.5° x 24±0.5°
Required Field-of-View to meet 24°x96° FOV requirement
IRD_29 - The four Camera ensemble Instrument field of view (FOV) shall be 24° ±
0.5° x 96° ± 2°.
Verification Method Inspection
Allocation LEN, HOD
7.3.2
L4_CAM_23 Camera Boresight Alignment
ID Number
Requirement
Rationale
Parent(s)
L4_CAM_23 Camera Boresight Alignment
Each Camera shall have attachment surfaces that are coplanar to allow Camera boresight angles to be 12° ±1° and 36°± 1° relative to a common reference plane
(defined by the Camera Plate).
The orientation of each Camera boresight relies on precision of mounting surfaces because alignment shims are not required.
IRD_59 - The four Cameras shall be assembled on the Camera plate per reference dwg. # 821112 such that the Camera boresight angles are +12° ±1° and -12° ± 1°,
+36°± 1°, and - 36° ±1° relative to a common reference plane.
Verification Method Analysis, Inspection
Allocation FLX, LEN
7.3.3
L4_CAM_09 Effective Area - Camera
ID Number
Requirement
Rationale
L4_CAM_09 Effective Area - Camera
Each Camera shall have an effective collecting area, defined as the product of the geometric area of the entrance pupil, the mean CCD QE over the 0.6-1.0 µm bandpass, the transmissivity of the optics, and the transmissivity of the bandpass filter, of at least 50 cm 2 .
Requirement is for imaging a particular star, which is only viewable by one Camera
Parent(s) at a time: therefore, the allocation at L3 is the same at L4 (per Camera). Effective area drives stellar shot noise (impacting stars with magnitude I>7), which is in turn a major contributor to total photometric error.
IRD_30 - The Instrument shall have an effective collecting area, defined as the product of the geometric area of the entrance pupil, the mean CCD QE over the
0.6-1.0 µm bandpass, the transmissivity of the optics, and the transmissivity of the bandpass filter, of at least 50 cm2.
IRD_63 - The Instrument shall achieve a total photometric precision, accounting for all statistical and systematic error sources other than stellar variability, to be less than 230 ppm for a K5V star at I=10 on a one hour timescale.
Verification Method Analysis, Test
Allocation LEN, DET
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7.3.4
L4_CAM_54 Systematic Error - Camera CCD Gain
[Deleted]
Document 37-11602
7.3.5
L4_CAM_10 Photometric Error: Temperature Effects
ID Number
Requirement
Rationale
L4_CAM_10 Systematic Error - Camera CCD QE
The Camera shall limit variation in ensquared energy (due to PSF Variation, Gain
Variation and QE Variation) to less than 2800 ppm/°C for the following apertures and field angles:
Field angle Aperture Size
(deg) (microns)
(0,0) 75x75
(0,6) 75x75
(0,11) 75x75
(11,11) 105x105
Flowdown from MRD_27. Allocation details in the Allocations Reference
Document (ARD_17). Max expected temperature variation = 5°C x 2800 ppm/°C =
14000 ppm. This complies with the allocation in the V9 Systematic Noise Budget.
Nominal allocations are broken out as: 600ppm/°C PSF Variation, 1000ppm/°C
Gain Variation and 1200ppm/°C QE Variation.
Parent(s) IRD_31 - The instrument shall limit variation in ensquared energy of any camera relative to the camera’s individual boresight to < 700 ppm over any 1 hour period during HASO, for the following apertures and field angles:
Field angle Aperture Size
(deg) (microns)
(0,0) 75x75
(0,6) 75x75
(0,11) 75x75
(11,11) 105x105
Verification Method Analysis
Allocation LEN, DET
7.3.6
L4_CAM_48 Change in CCD Gain - Camera
[Deleted]
7.3.7
L4_CAM_49 Change in CCD QE – Camera
[Deleted]
7.3.8
L4_CAM_11 Distortion Induced Image Motion - Camera
[Deleted]
7.3.9
L4_CAM_46 Systematic Error: Periodic Error Residual - Camera
ID Number
Requirement
Rationale
Parent(s)
L4_CAM_46 Systematic Error: Periodic Error Residual - Camera
Each Camera shall limit the heat flow from the FPE such that the average Camera temperature changes no more than 0.1K/hr during HASO.
Thermal impact of the CCD temperature variation shall be limited.
IRD_53 - The Instrument shall limit the amplitude of periodic thermal variations in the CCD with periods from 1-24 hours to less than 500 mK.
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Allocation DET
Document 37-11602
7.3.10
L4_CAM_05 BPFF - Camera
ID Number
Requirement
Rationale
L4_CAM_05 BPFF - Camera
The BPFF of a point source image of blackbody sources at both T=3300K and
T=4500K shall be greater than 0.40 at 0° field angle, 0.35 at 6° field angle, 0.35 at
12° field angle, and 0.25 at 17° field angle over the selected operating temperature range of -75ᴼC ± 10ᴼC.
Image performance required for sensitivity to transiting planets. Image BPFF is a major driver to limiting background shot noise from the sky, which is a major contributor to the total photometric error.
Parent(s) IRD_63 - The Instrument shall achieve a total photometric precision, accounting for all statistical and systematic error sources other than stellar variability, to be less than 230 ppm for a K5V star at I=10 on a one hour timescale.
Verification Method Test, Analysis
Allocation LEN, DET
7.3.11
L4_CAM_28 Readout Noise - Camera
ID Number
Requirement
Rationale
Parent(s)
L4_CAM_28 Readout Noise - Camera
The readout noise of each Camera CCD shall be less than 20 electrons rms.
Readout noise, the noise introduced by reading out the CCD, is a major contributing source of photometric error, especially for faint stars.
IRD_63 - The Instrument shall achieve a total photometric precision, accounting for all statistical and systematic error sources other than stellar variability, to be less than 230 ppm for a K5V star at I=10 on a one hour timescale.
Verification Method Analysis
Allocation DET
7.3.12
L4_CAM_12 Stray Light - Camera
ID Number
Requirement
L4_CAM_12 Stray Light - Camera
Each Camera shall limit stray light interference to < 1e-7 outside of angles >30° from the Camera boresight.
Maintain observation integrity for at least 20 days out of 27 days. Rationale
Parent(s) IRD_33 - The Instrument shall limit stray light interference to enable science data collection from each target star for at least 20 days during each two-orbit observing sector.
Verification Method Analysis
Allocation LEN, DET, HOD
7.3.13
L4_CAM_51 Instrument Return to Science – Camera
[Deleted]
7.4
Robustness and Safety Requirements
7.4.1
L4_CAM_13 Fault Containment-Camera
[Deleted]
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7.4.2
L4_CAM_52 Hazard Mitigation – Camera
Document 37-11602
ID Number L4_CAM_52 Hazard Mitigation – Camera
Requirement
Rationale
Parent(s) IRD_36 - The Instrument shall have no Critical or Catastrophic Hazards.
Verification Method Inspection
Allocation
Each Camera shall have no Critical or Catastrophic Hazards.
Flowdown from IRD_36
7.4.3
L4_CAM_14 Power Shutdown – Camera
ID Number
Requirement
L4_CAM_14 Power Shutdown – Camera
Each Camera shall be robust to sudden removal of power from the DHU with no damage or permanent impact to performance.
Rationale
Parent(s)
No damage should result from sudden power removal.
IRD_38 - The Instrument shall be robust to sudden removal of power from the spacecraft with no damage or permanent impact to performance.
Verification Method Test, Analysis
Allocation DET
7.4.4
L4_CAM_15 SEU – Camera
ID Number
Requirement
Rationale
L4_CAM_15 SEU - Camera
Each Camera shall be robust to any Single Event Upset (SEU) without compromising the health or safety of the Observatory.
SEUs should not impact the Instrument such that the health of the Observatory is jeopardized.
Parent(s) IRD_40 - The Instrument shall be robust to any Single Event Upset (SEU) without compromising the health or safety of the Observatory.
Verification Method Analysis
Allocation DET
7.4.5
L4_CAM_16 Sun Pointing
ID Number
Requirement
Rationale
L4_CAM_16 Sun Pointing
Each Camera shall tolerate, for no greater than 15 minutes, sun exposure inside a shape centered on the SC +Z axis:
• ±30° about the X-axis
• ±50° about the Y-axis
This limitation will prevent a thermal gradient from developing that could overstress the Camera lenses.
IRD_41 - The Cameras shall tolerate, for no greater than 15 minutes, sun exposure Parent(s) inside a shape centered on the SC +Z axis:
• ±30° about the X-axis
• ±50° about the Y-axis
Verification Method Analysis
Allocation LEN
7.5
General Requirements
7.5.1
L4_CAM_47 Camera Life
ID Number
Requirement
L4_CAM_47 Camera Life
Each Camera shall be designed to operate for a 2 year mission after a 2 month post-launch commissioning phase.
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Rationale
Parent(s)
Flowdown from IRD_42.
IRD_42 - The Instrument shall be designed to operate for at least a 2 year mission after a 2 month post-launch commissioning phase.
Verification Method Analysis
Allocation LEN, DET
7.5.2
L4_CAM_17 Environment – Camera
ID Number
Requirement
Rationale
L4_CAM_17 Environment – Camera
Each Camera shall comply with the ERD.
Each Camera will be analyzed and tested as specified per the ERD to verify that environmental requirements have been met and an Environmental Verification
Report will be generated.
Parent(s) IRD_43 - The Instrument shall comply with the Environmental Requirements
Document.
Verification Method Analysis, Test
Allocation
7.5.3
L4_CAM_25 Camera Temperature - Lens
ID Number
Requirement
Rationale
L4_CAM_25 Camera Temperature - Lens
Each Camera shall maintain the lens assembly at an operating temperature of -
75°C ±10 °C during HASO.
Operating temperature of lens assemblies was chosen based on thermal model optimization. Tolerance range includes performance margin and thermal model uncertainty.
Parent(s) IRD_44 - The Instrument shall maintain the centers of the Camera lens assemblies at an operating temperature of -75ᴼC ± 10ᴼC during nominal operations across
LAHO and HASO, given the thermal environment provided by the spacecraft as specified in the MTICD.
Verification Method Analysis, Test
Allocation DET, LEN
7.5.4
L4_CAM_31 Lens Temperature Variation
ID Number
Requirement
Rationale
Parent(s)
L4_CAM_31 Lens Temperature Variation
The variation of the average lens temperature for each Camera shall be no greater than 5°C during HASO for an entire orbit.
Allocated from the systematic error budget.
IRD_44 - The Instrument shall maintain the centers of the Camera lens assemblies at an operating temperature of -75ᴼC ± 10ᴼC during nominal operations across
LAHO and HASO, given the thermal environment provided by the spacecraft as specified in the MTICD.
Verification Method Analysis
Allocation
7.5.5
L4_CAM_18 CCD Temperature
ID Number
Requirement
Rationale
L4_CAM_18 CCD Temperature
Each Camera shall maintain the CCDs at an operating temperature of <-60°C during nominal operational conditions.
CCD photometric performance is affected by warm columns / pixels and dark current. In order to meet noise requirements, the CCD temperature must be below -60°C.
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Parent(s) IRD_61 - The Instrument shall maintain the Camera CCDs at an operating temperature of < -60ᴼC during nominal operations across LAHO and HASO, given the thermal environment provided by the spacecraft as specified in the MTICD.
Verification Method Analysis, Test
Allocation DET
7.5.6
L4_CAM_26 Power Dissipation
[Deleted]
7.5.7
L4_CAM_19 MTICD and MICD - Camera
ID Number
Requirement
Rationale
Parent(s)
L4_CAM_19 MTICD and MICD – Camera
Each Camera shall conform to the MTICD and MICD.
Flowdown from IRD_45.
IRD_45 - The Instrument shall conform to the MTICD.
Verification Method Inspection
Allocation
7.5.8
L4_CAM_20 EICD - Camera
ID Number
Requirement
Rationale
L4_CAM_20 EICD - Camera
Each Camera shall conform to the EICD.
Flowdown from IRD_46. EICD includes requirements for component grounding and ESD control.
Parent(s) IRD_46 - The Instrument shall conform to the EICD.
Verification Method Inspection, Test
Allocation LEN, DET, FLX, HOD
7.5.9
L4_CAM_53 CAM-DHU ICD – Camera
ID Number
Requirement
Rationale
L4_CAM_20 EICD – Camera
Each Camera shall conform to the CAM-DHU ICD.
The electrical and data interfaces between the Cameras and the DHU are defined in the CAM-DHU ICD.
Parent(s)
Verification Method Test, Inspection, Demonstration
Allocation DET
7.5.10
L4_CAM_21 CRF – Camera
[Deleted]
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7.5.11
L4_CAM_22 External Optical Surface – Contamination Control
ID Number L4_CAM_22 External Optical Surface – Contamination Control
Requirement
Rationale
Each Camera shall be delivered for Observatory Integration and Test with a cleanliness level on the external surface of front optical element of 350A per MIL-
STD-1246C.
The Instrument has a more stringent cleanliness requirement at this phase to accommodate predicted contamination due to Observatory Integration, Test and
Launch operations. Additional detail is provided in the TESS Contamination
Control Plan.
Parent(s) IRD_49 - The Instrument shall be delivered for Observatory Integration and Test with a cleanliness level on the external surface of front optical element of 350A per MIL-STD-1246C.
Verification Method Inspection, Test
Allocation LEN
7.5.12
L4_CAM_29 CCD - Contamination Control
ID Number
Requirement
Rationale
Parent(s)
L4_CAM_29 CCD – Contamination Control
Each Camera shall be delivered for Observatory Integration and Test with a cleanliness level on the CCD surface of 150A/2 per MIL-STD-1246C.
Contamination reduces effective area of the Camera.
IRD_64 - The Instrument shall be delivered for Observatory Integration and Test with a cleanliness level on the CCD surface of 150A/2 per MIL-STD-1246C.
Verification Method Inspection
Allocation DET
7.5.13
L4_CAM_30 Internal Optical Surfaces -Contamination Control
ID Number
Requirement
Rationale
L4_CAM_30 Internal Optical Surfaces - Contamination Control
Each Camera shall be delivered for Observatory Integration and Test with a cleanliness level on the internal optical surfaces of 250A/2 per MIL-STD-1246C.
Instrument has a more stringent cleanliness requirement to allow for contamination during Observatory Integration and Test and Launch Operations.
IRD_66 - The Instrument shall be delivered for Observatory Integration and Test Parent(s) with a cleanliness level on the internal optical surfaces of 250A/2 per MIL-STD-
1246C.
Verification Method Inspection
Allocation LEN
7.5.14
L4_CAM_27 Purge Ports - Camera
ID Number
Requirement
Rationale
L4_CAM_27 Purge Ports - Camera
Each Camera shall have purge ports to support a purge system that will maintain a dry nitrogen environment inside the Camera through launch preparations in compliance with the TESS Contamination Control Plan.
Instrument is responsible for providing a purge system and the required ground support equipment to meet MRD_120.
IRD_50 - The Instrument shall have a purge system to maintain a dry nitrogen Parent(s) environment inside the Cameras through launch preparations. Details describing the implementation of this purge system shall be in the TESS Contamination
Control Plan.
Verification Method Inspection
Allocation DET
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7.5.15
L4_CAM_32 ERD 3.1.1.1 Limit Loads - Camera
[Deleted]
Document 37-11602
7.5.16
L4_CAM_33 ERD 3.1.3 Sine Vibration - Camera
[Deleted]
7.5.17
L4_CAM_34 ERD 3.1.4 Random Vibration - Camera
[Deleted]
7.5.18
L4_CAM_35 ERD 3.1.5 Shock - Camera
[Deleted]
7.5.19
L4_CAM_36 ERD 3.1.7 Ambient Pressure -Camera
[Deleted]
7.5.20
L4_CAM_37 ERD 3.1.9 Humidity - Camera
[Deleted]
7.5.21
L4_CAM_38 ERD 3.1.8.2 Temperature Performance Requirements – Camera
[Deleted]
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Acronym
SEU
SOH
STOP
SW
TBD
TBR
TESS
FOV
FW
HAR
HASO
HOD
HW
ICD
IRD
LAHO
LEN
MAU
MICD
MRD
MTICD
PDR
POC
PPS
QE
ACS
ARD
CAM
CCD
CCSDS
CDR
CPA
CSA
DET
DHU
EICD
ERD
FFI
FLX
FMEA
FMECA
Release Date: 14 June 2015
Title: TESS Instrument Camera L4 Requirements Rev A
8.0
LIST OF ABBREVIATIONS AND ACRONYMS
Document 37-11602
Definition
Attitude Control System
Allocations Reference Document
Camera (L4 subsystem designation)
Charge-Coupled Device
Consultative Committee for Space Data Systems
Critical Design Review
Camera Plate Assembly (L4 subsystem designation)
Camera Structure Assembly (part of the Instrument)
Detector Assembly (L5 assembly designation)
Data Handling Unit
Spacecraft-Instrument Electrical Interface Control Document
Environmental Requirements Document
Full Frame Images
Camera Flexures (L5 assembly designation)
Failure Mode and Effects Analysis
Failure Modes, Effects and Criticality Analysis
Field of View
Firmware
Harness (L4 subsystem designation)
High Altitude Science Operations
Lens Hood (L5 assembly designation)
Hardware
Interface Control Document
Instrument Requirements Document
Low Altitude Housekeeping Operations
Lens Assembly (L5 assembly designation)
Master Avionics Unit
Spacecraft-Instrument Mechanical Interface Control Document
Mission Requirements Document
Mechanical Thermal Interface Control Document (ref doc 4)
Preliminary Design Review
Payload Operations Center
Pulse Per Second
Quantum Efficiency
Single Event Upset
State-of-Health
Structural Thermal Optical Performance
Software
To Be Determined
To Be Reviewed
Transiting Exoplanet Survey Satellite
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