DRAFT_Specifications_.pdf

RESTORE-L-SPEC-001394

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RESTORE-L

VISION SENSOR SUBSYSTEM

CAMERA TECHNICAL

SPECIFICATION

Goddard Space Flight Center Greenbelt, Maryland

June, 2016

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CM FOREWORD

This document is a Satellite Servicing Capabilities Office (SSCO) Configuration Management

(CM)-controlled document. Changes to this document require prior approval of the applicable

Configuration Control Board (CCB) Chairperson or designee. Proposed changes shall be submitted to the SSCO Code 408 CM Office (CMO), along with supportive material justifying the proposed change. Changes to this document will be made by complete revision.

Questions or comments concerning this document should be addressed to:

NASA/Goddard Space Flight Center

SSCO, Code 408

Attention: Configuration Management Office

Greenbelt, Maryland 20771

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SATELLITE SERVICING CAPABILITIES OFFICE

DOCUMENT CHANGE RECORD

Date: June 10, 2016 Sheet 1 of 1

TITLE: Restore-L Vision Sensor Subsystem Camera Performance Specification

REV

LEVEL

DESCRIPTION OF CHANGE AUTHORIZATION

A

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Restore-L Vision Sensor Subsystem Camera Technical Specification

Prepared By:

Approved

Ross Henry

Restore-L Vision Sensor Subsystem Lead, NASA/551

6/10/16

Date

Reviewed By:

Approved

Kate Chamberlin

Restore-L Vision Sensor Subystem Deputy Lead, SGT/408

Kelvin Garcia

Restore-L I&T Lead, NASA/568

Roger Chiei

Restore-L Avionics Lead, LMCO/408

Eugene Skelton

Restore-L RPO Lead, LMCO/408

Torchia Kelly

Restore-L Mechanical Lead, Orbital ATK/408

Teri Gregory

Restore-L Thermal Lead, NASA/545

Nathan Smith

Restore-L Materials Lead, NASA/541

Seshagiri Nadendla

Restore-L VDSU Lead, J&T/408

Gardell Gefke

Restore-L Robot Systems Engineer, AS&D/408

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Arthur Lieberman

Restore-L Stress Analyst, Orbital ATK/408

Approved By:

Approved

Robert Smith

Restore-L Project Manager, NASA/408

Bo Naasz

Restore-L Mission Systems Engineering Lead, NASA/599

Robert Dedalis

Restore-L Chief Safety Officer, NASA/380

Joe Joyner

Restore-L Quality Assurance Engineer, Orbital ATK/408

Tina Montt De Garcia

Restore-L Contamination Lead, NASA/546 ii https://sscongin.ndc.nasa.gov/

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TABLE OF CONTENTS

Page

1.0 Introduction .................................................................................................................... 1-1

1.1 Purpose ................................................................................................................. 1-1

1.2 Scope .................................................................................................................... 1-1

1.3 Mission Concept of Operations (CONOPS) ........................................................ 1-1

1.4 Verb Application .................................................................................................. 1-2

1.5 Hardware Description .......................................................................................... 1-2

1.5.1 Flight Model............................................................................................. 1-2

1.5.2 Qualification Model ................................................................................. 1-3

1.5.3 Engineering Development Unit ............................................................... 1-3

1.5.4 Electrical Ground Support Equipment ..................................................... 1-3

1.6 Document Change Procedure .............................................................................. 1-3

2.0 Applicable Documents ................................................................................................... 2-1

3.0 Technical Requirements ................................................................................................ 3-1

3.1 General Requirements .......................................................................................... 3-1

3.1.1 Mission Life ............................................................................................. 3-1

3.1.2 Warm-Up Time ........................................................................................ 3-1

3.1.3 Shelf Life ................................................................................................. 3-1

3.1.4 Dormancy ................................................................................................. 3-1

3.1.5 Demise ..................................................................................................... 3-1

3.2 Optical Requirements........................................................................................... 3-2

3.2.1 Focal Plane Array Requirements ............................................................. 3-2

3.2.2 Auto-Exposure ......................................................................................... 3-4

3.2.3 Sun Exposure ........................................................................................... 3-4

3.2.4 Ultra-Violet (UV) / Infrared (IR) Blocking Filter.................................... 3-4

3.3 Mechanical Characteristics .................................................................................. 3-5

3.3.1 Mechanical Interface ................................................................................ 3-5

3.3.2 Mechanical CAD Model .......................................................................... 3-5

3.3.3 Mass ......................................................................................................... 3-5

3.3.4 Physical Envelope .................................................................................... 3-6

3.3.5 Mechanical Mounting .............................................................................. 3-6

3.3.6 Mechanical Mounting Notation ............................................................... 3-6

3.3.7 Alignment Features .................................................................................. 3-6

3.3.8 Lens Mount .............................................................................................. 3-6

3.3.9 Focal Plane Array to Primary Mounting Interface Alignment ................ 3-6

3.3.10 Optical Axis to Lens Mount Alignment................................................... 3-6

3.3.11 Electrical Connector Location ................................................................. 3-6

3.3.12 Chassis Grounding ................................................................................... 3-7

3.3.13 Identification and Marking ...................................................................... 3-7

3.4 Interface & Electrical Requirements .................................................................... 3-8

3.4.1 Power Interface ........................................................................................ 3-8

3.4.2 Video Interface....................................................................................... 3-10 iii https://sscongin.ndc.nasa.gov/

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3.4.3 Command Interface ................................................................................ 3-12

3.4.4 Telemetry Interface ................................................................................ 3-14

3.4.5 General Electrical Requirements ........................................................... 3-15

3.5 Thermal Requirements ....................................................................................... 3-20

3.5.1 Thermal Model....................................................................................... 3-20

3.5.2 Thermal Model Correlation ................................................................... 3-20

3.5.3 Temperature Sensor ............................................................................... 3-20

3.5.4 Temperature Limits ................................................................................ 3-20

3.6 Environmental Qualification Requirements ...................................................... 3-21

3.6.1 Static Loads ............................................................................................ 3-21

3.6.2 Random Vibration .................................................................................. 3-21

3.6.3 Acoustic Impingement ........................................................................... 3-21

3.6.4 Thermal .................................................................................................. 3-21

3.6.5 Vacuum .................................................................................................. 3-21

3.6.6 EMI / EMC ............................................................................................ 3-22

3.6.7 Radiation ................................................................................................ 3-23

3.6.8 Humidity ................................................................................................ 3-30

3.6.9 Venting ................................................................................................... 3-31

3.6.10 Atomic Oxygen ...................................................................................... 3-31

4.0 Verification Requirements ............................................................................................ 4-1

4.1 Verification Rationale .......................................................................................... 4-1

4.2 Inspection ............................................................................................................. 4-1

4.2.1 Final Inspection ........................................................................................ 4-1

4.3 Analysis................................................................................................................ 4-1

4.4 Test ....................................................................................................................... 4-1

4.4.1 Test Failure and Control of Nonconforming Product .............................. 4-1

4.4.2 Failure During Tests ................................................................................ 4-2

4.4.3 Modification of Hardware ........................................................................ 4-2

4.4.4 Re-Test Requirements .............................................................................. 4-2

4.5 Required Verification Tests ................................................................................. 4-3

4.5.1 Mass and Envelope Measurements .......................................................... 4-3

4.5.2 Performance and Functional Tests ........................................................... 4-3

4.5.3 EMI / EMC Test....................................................................................... 4-3

4.5.4 Load Tests ................................................................................................ 4-4

4.5.5 Random Vibration .................................................................................... 4-5

4.5.6 Sine Vibration .......................................................................................... 4-5

4.5.7 Thermal Vacuum Test.............................................................................. 4-6

5.0 Appendix B: Acronym List ........................................................................................... 5-1 iv https://sscongin.ndc.nasa.gov/

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LIST OF FIGURES

Figure Page

Figure 1-1: Restore-L Mission ConOps ....................................................................................... 1-1

Figure 3-1: Silicon Dose Depth Kernels for Restore LEO and ARRM Environments ............. 3-24

Figure 3-2: Silicon DDD equivalent fluence for Restore-L and ARRM Environments............ 3-26

Figure 3-3: Worst case integral solar proton fluxes for SEE evaluation ................................... 3-29

Figure 4-1: Thermal Vacuum Profile ........................................................................................... 4-6

LIST OF TABLES

Table Page

Table 2-1: Applicable Documents ............................................................................................... 2-1

Table 3-1: Shelf Life .................................................................................................................... 3-1

Table 3-2: Temperature Limits at Mounting Interface .............................................................. 3-21

Table 3-3: Required EMI/EMC Tests ........................................................................................ 3-22

Table 3-4: Restore-L & ARRM Radiation Environment ........................................................... 3-23

Table 3-5: Dose Depth Kernels for Restore LEO and ARRM Environments ........................... 3-25

Table 3-6: DDD equivalent fluence for Restore-L & ARRM Environments ............................ 3-27

Table 3-7: Worst Case Integral Peak Solar Proton Flux (Solar Maximum) .............................. 3-30

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1.0 INTRODUCTION

1.1 PURPOSE

The purpose of this document is to define the technical specifications for a visible wavelength camera system. This camera system is the primary sensor that will comprise the Vision Sensor

Subsystem (VSS) of NASA Goddard Space Flight Center’s (GSFC) Restore-L satellite servicing mission.

1.2 SCOPE

This specification document describes the optical, electrical, mechanical, operating environment, and verification testing requirements for a space qualified, visible wavelength camera system for the GSFC Restore-L satellite servicing mission. This hardware will be referred to herein as the, “VSS camera.” The commercial vendor selected to manufacture the VSS camera will be referred to herein as the, “Contractor.” NASA GSFC will be referred to herein as the, “Government.”

This document contains the majority of the technical information regarding the VSS camera, while the programmatic aspects of its build are covered in the corresponding Statement of Work

(SOW) document number, RESTORE-L-SOW-001885.

1.3 MISSION CONCEPT OF OPERATIONS (CONOPS)

The Restore-L satellite servicing mission aims to autonomously rendezvous with, and robotically service an existing government-owned satellite. A summary of the concept of operations for the mission is shown below. The VSS camera will be utilized during the ‘Servicing’ portion of the mission as shown below.

Figure 1-1: Restore-L Mission ConOps

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1.4 VERB APPLICATION

Statements containing the verb “shall” are binding requirements regardless of location within this specification. The verbs “should” and “may” are used for stating non-mandatory goals or denoting a statement of best practice. The verb “will” is used in a statement of fact, expected occurrence, or declaration of purpose.

1.5 HARDWARE DESCRIPTION

The Government desires to procure a small, yet versatile visible wavelength spaceflight camera.

The Government envisions this camera system to be of the type commonly referred to in industry as a, “camera head” unit. That is, this camera system contains a lens, focal plane array, and supporting electronics that outputs the camera’s imagery. Complicated data manipulation and / or image processing is meant to occur outside of the camera, further downstream inside of the

Restore-L avionics subsystem.

The Government is still in the process of evaluating the exact optical specifications for the lens assemblies that each VSS camera will require. Therefore, the Contractor shall assume that they are only responsible for manufacturing the camera body and that the Government will provide the final spaceflight-ready optical lenses via Government Furnished Equipment (GFE) methods.

The Contractor shall be responsible for integrating these lenses onto each VSS camera and taking the entire camera system through environmental testing as described in Section 3.7. The

Government also requires that some VSS camera units be delivered with a commercial grade laboratory lens. Those specific details are outlined in the accompanying Statement of Work

(SOW) document number, RESTORE-L-SOW-001885.

The Government is also considering this camera design for future NASA missions such as the

Asteroid Robotic Redirection Mission (ARRM). As such, some of the environment requirements contained herein are enveloping requirements for both missions.

The following hardware descriptions are provided to delineate between the different types of deliverables requested in the Statement of Work (SOW) document number, RESTORE-L-SOW-

001885.

1.5.1 Flight Model

A flight model is the actual end item that is intended for deployment and operations in a space environment. It shall be subjected to formal functional and environmental acceptance testing as defined by GSFC-STD-7000A, “General Environment Verification Standard (GEVS) for GSFC

Flight Programs and Projects.” A flight unit will be subject to all sections and specifications within this document.

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1.5.2 Qualification Model

A qualification model is the development end item on which a partial or complete prototype qualification test campaign has been performed per GSFC-STD-7000A. The qualification model is tested to levels that demonstrate desired margins, particularly for exposing fatigue stress. In some cases this may mean testing to failure. The VSS camera qualification unit is not intended for spaceflight.

1.5.3 Engineering Development Unit

An Engineering Development Unit (EDU) fully reflects the intended final design of the flight model. In a traditional definition of an EDU, commercial grade Electrical, Electronic and

Electromechanical (EEE) parts may be used in an effort to reduce overall program costs. In this case, the Government desires that the VSS camera EDUs be a carbon copy of the flight units in terms of form, fit, build and function. The EDU cameras will be used for requirements verification, functional performance testing, verification of Electronic Ground Support

Equipment (EGSE), and may be used for Electromagnetic Compatibility (EMC) testing. The

VSS camera EDUs are not intended for spaceflight.

1.5.4 Electrical Ground Support Equipment

The electrical ground support equipment (EGSE) for the VSS camera shall be capable of interfacing with and operating a single VSS camera as a standalone component. The EGSE shall allow a user to power, command, view and save images/video from the VSS camera units.

Additionally, the EGSE shall display the real-time telemetry emanating from the camera units.

Depending on the architecture of the EGSE, components may include a power supply, breakout box and control computer.

1.6 DOCUMENT CHANGE PROCEDURE

The Satellite Servicing Capabilities Office (SSCO, Code 408) maintains configuration control of this document. Once baselined, all changes will require a Configuration Change Request (CCR) to be processed through the SSCO Windchill Configuration Management System.

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2.0 APPLICABLE DOCUMENTS

The following documents in effect on the day this specification was signed shall apply to the fabrication and to the electrical, mechanical, and environmental requirements of the VSS camera to the extent specified herein. In the event of conflict between this specification and any referenced document, this specification will govern, with the exception of the Statement of

Work, RESTORE-L-SOW-001885, in which case the SOW takes precedence. The following is a list of the applicable specifications and publications.

Table 2-1: Applicable Documents

Document No. Title

ASTM E595

Standard Test Method for Total Mass Loss and Collected Volatile

Condensable Materials from Outgassing in a Vacuum Environment

GSFC-STD-7000A

Goddard Space Flight Center General Environmental Verification

Standard (GEVS)

NASA-HDBK-4002

Avoiding Problems Caused by Spacecraft On-Orbit Internal Charging

Effects

NASA-HDBK-4006 Low Earth Orbit Spacecraft Charging Design Handbook

RESTORE-PLAN-000513

Restore Servicing Vehicle (RSV) EMI/EMC & RF Compatibility

Control Plan

RESTORE-L-SPEC-001804

Restore-L Mission Natural and Induced Operating Environments

Specification

RESTORE-L-SOW-001885 Restore-L Vision Sensor Subsystem Camera Statement of Work

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3.0 TECHNICAL REQUIREMENTS

3.1 GENERAL REQUIREMENTS

3.1.1 Mission Life

The VSS camera shall operate within specification with no maintenance or calibration during the component mission life, defined to be one (1) year herein with a 10% operational duty cycle.

3.1.2 Warm-Up Time

The VSS camera shall meet performance requirements within one (1) minute of the application of power, for any of the specified environmental conditions defined herein, to the end of life of the component.

3.1.3 Shelf Life

The VSS camera shall operate within specification with no maintenance or calibration required up to five (5) years of storage under the conditions specified below.

Table 3-1: Shelf Life

Parameter Specification

Temperature: 25°C ± 15°C

Relative Humidity: 25% to 60%

Pressure: Sea Level to Vacuum (10-6 Torr)

3.1.4 Dormancy

The VSS camera shall operate within specification after three (3) years of dormancy in the operational environment.

3.1.5 Demise

The Contractor shall provide information and data to allow the Government to perform a demisability study for spacecraft disposal and re-entry.

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3.2 OPTICAL REQUIREMENTS

3.2.1 Focal Plane Array Requirements

3.2.1.1 Image Sensor Type

The VSS camera shall contain a solid state Complementary Metal-Oxide Semiconductor

(CMOS) focal plane array.

3.2.1.2 Wavelength Sensitivity

The VSS camera shall contain a focal plane array sensitive to visible wavelengths (~400 to ~700 nanometers) with mid-band peak responsivity greater than 1 V/lux.s.

3.2.1.3 Color Imagery

The VSS camera shall contain a focal plane array that provides color imagery via a Bayer pattern

Color Filter Array (CFA).

3.2.1.4 Image Resolution

The VSS camera shall contain a focal plane array that provides high-resolution video and imagery with a minimum 1280 x 1024 pixel resolution.

Note: Native sensor resolution may be higher.

3.2.1.5 Active Pixels

The VSS camera shall contain a focal plane array in which greater than 99% of the imaging pixels are alive and active (i.e. no more than 1% dead pixels).

3.2.1.6 Dynamic Range

The VSS camera shall contain a focal plane array with a linear dynamic range of ≥ 60 dB.

3.2.1.7 Frame Rate

The VSS camera shall contain a focal plane array that (a) provides high resolution video at a minimum frame rate of ten (10) frames per second (fps) at the resolution stated in requirement

3.2.1.4, and (b) outputs all pixels of the full frame image at a minimum rate of one (1) fps.

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3.2.1.8 Optical Format Minimum

The VSS camera shall contain a focal plane array whose diagonal dimension across the active pixel area is greater than 11mm (i.e. 2/3” optical format).

Note: Native optical format may be larger

3.2.1.9 Analog-to-Digital Conversion

The VSS camera shall contain a focal plane array with an on-chip Analog-to-Digital converter with a resolution of between 8 (minimum) and 12 (maximum) bits per pixel (bpp).

3.2.1.10 Windowing Capability

The VSS camera shall contain a focal plane array that performs on-chip Region-of-Interest (ROI)

(aka windowing) control.

3.2.1.11 Shutter Mode

The VSS camera shall contain a focal plane array that implements a global (snapshot) shutter mode.

3.2.1.12 Subsampling Mode

The VSS camera shall contain a focal plane array that performs on-chip subsampling to reduce the output resolution of the camera imagery without reducing the camera Field-of-View (FOV).

Note: For color sensors, the read-2-skip-2 (window/column) subsampling scheme is required.

3.2.1.13 Manual Commanding of FPA Parameters

The VSS camera shall accept and execute manual commands for the following specific focal plane array parameters:

Integration time (discrete pre-determined values)

Gain (discrete pre-determined values)

Frame Size (row & column size values)

Frame Rate (discrete pre-determined values)

Region of Interest control for window size and location

Analog-to-Digital Conversion (bits per pixel value)

Subsampling Mode (on / off)

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3.2.2 Auto-Exposure

The VSS camera shall employ an Automatic Gain & Exposure Control (AGEC) algorithm running internal to the camera to adjust for dynamic on-orbit lighting conditions.

3.2.2.1 Auto-Exposure Control

The auto-exposure control for the VSS camera shall be turned on and off via manual command.

3.2.3 Sun Exposure

3.2.3.1 Unpowered State

The VSS camera shall not be permanently damaged by sun exposure, within the unit’s field of view, for an indefinite duration when the unit is powered off.

3.2.3.2 Powered State

The VSS camera shall not be permanently damaged by sun exposure, within the unit’s field of view, for up to 15 minutes duration when the unit is powered on. The VSS camera shall meet its performance requirements within five (5) minutes after cessation of sun exposure.

3.2.4 Ultra-Violet (UV) / Infrared (IR) Blocking Filter

The VSS camera shall contain an internal UV / IR blocking filter to maximize the camera’s ability to generate accurate color images. The properties of this UV / IR blocking filter shall be the following:

a) Short-wavelength transmittance cut-on (FWHM): 400 nm

b) Long-wavelength transmittance cut-off (FWHM): 700 nm

c) Wavelength tolerance: ± 10 nm

d) The slope of the short-wave and long-wave cut-off shall be less than 10%

e) In-band (400nm – 700nm) average transmittance: > 90%

f) Out-of-band rejection: < 1e-3

g) Transmitted Wavefront Error (TWE): λ/4 @ 633 nm

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3.3 MECHANICAL CHARACTERISTICS

3.3.1 Mechanical Interface

The VSS camera mechanical interface shall be defined by the Contractor with a mechanical

Interface Control Document (ICD).

3.3.1.1 Coordinate Systems

The Contractor shall define a right-handed orthogonal coordinate frame, including an origin for the mechanical chassis of the VSS camera. This coordinate frame convention shall be defined in the mechanical ICD and used for all environmental testing (vibe, shock, etc.) and optical alignment activities.

3.3.1.2 Mass Properties

The Contractor shall include the approximate mass to within 10 grams and location of the center of mass of the VSS camera to within 1 cm in the mechanical ICD.

3.3.1.3 Physical Dimensions

The Contractor shall include the overall physical dimensions, locations and sizes of electrical connectors, optical datums, centers of optical surfaces, mounting hole locations, types and sizes of mounting bolts or other fasteners and any other critical mechanical infrastructure of the VSS camera in the mechanical ICD.

3.3.2 Mechanical CAD Model

The Contractor shall provide the Government with a STEP file of the as-designed VSS camera.

The step file shall contain all external interfaces/features representative of the as-built VSS camera.

3.3.3 Mass

The total mass of the VSS camera without lens shall be less than or equal to 400 grams.

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3.3.4 Physical Envelope

The VSS camera shall have bounding box dimensions of equal to or less than 5.715 cm (width) x

6.9 cm (length) and 5.715 cm (height) not including the lens, where the length dimension is parallel to the VSS camera optical boresight and the height and width dimensions span the front face of the camera enclosure.

3.3.5 Mechanical Mounting

The VSS camera shall include a mechanical mounting solution that includes multiple threaded fastener holes on each of the three adjoining orthogonal faces of the camera chassis that are parallel to the optical boresight. Fastener holes shall be blind and not penetrate the interior of the camera housing.

3.3.6 Mechanical Mounting Notation

The Contractor shall define one of the mounting interfaces of the VSS camera as the Primary

Mounting Interface and note its location on the mechanical ICD.

3.3.7 Alignment Features

The VSS camera mounting surfaces shall utilize precision alignment features (such as an alignment pin / hole) to maintain alignment when mounting.

Note: Specific alignment method shall be approved by the Government.

3.3.8 Lens Mount

The VSS camera shall include a C-mount type lens mount that accepts any C-Mount lens with a

17.52mm flange focal distance and an ANSI 1-32 UN 2A thread.

3.3.9 Focal Plane Array to Primary Mounting Interface Alignment

The VSS camera focal plane array shall be aligned to the camera’s primary mounting interface to within ± 10 arcminutes in roll, pitch and yaw.

3.3.10 Optical Axis to Lens Mount Alignment

The optical axis of the VSS camera as defined by the center pixel of the focal plane array shall be aligned to the camera’s C-Mount interface horizontally and vertically to within ± 30 arcminutes.

3.3.11 Electrical Connector Location

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The VSS camera shall have all electrical connectors that implement power, video, command, and telemetry located on the camera face opposite of the face containing the camera lens.

3.3.12 Chassis Grounding

The VSS camera shall provide a dedicated electrical chassis ground point that conforms to

Section 3.4.5.7.

Note: Specific grounding method shall be approved by the Government.

3.3.13 Identification and Marking

Each unit shall be permanently marked with the part number and a unique sequential serial number on an area designated by the mechanical Interface Control Drawing (ICD) in a manner that will endure the following without fading or removal:

a) Typical handling in aerospace manufacturing

b) Cleaning with isopropyl alcohol

c) Handling with gloves

d) Mechanical fastening

e) Environments listed in Section 3.6

The format of the unique serial number shall be defined such that flight, qualification, and EDU units of the VSS camera are easily distinguishable from one another. (i.e. F001 for flight, Q001 for qual, E001 for EDU, etc.)

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3.4 INTERFACE & ELECTRICAL REQUIREMENTS

3.4.1 Power Interface

3.4.1.1 Operating Voltage Level

The VSS camera shall be designed to operate over the input voltage of 5.0 V ± 0.5 Vdc at its primary input.

3.4.1.2 Maximum Steady State Power

The maximum steady state input power of the VSS camera shall not exceed 2.75 Watts.

3.4.1.3 Maximum Steady State Current

The maximum steady state current draw shall not exceed 0.55 amps at 5.0Vdc.

3.4.1.4 Input Ripple

The VSS camera shall comply with the input power line ripple and noise specification of ≦5 % peak to peak (p-p) when measured at 100 MHz bandwidth.

3.4.1.5 Camera Reflected Ripple

The VSS camera shall limit the reflected ripple to within +/- 0.10 volts peak to peak (p-p) on its input 5 Vdc nominal power line.

3.4.1.6 In-Rush Current

Maximum in-rush current of the VSS camera shall not exceed 0.9 amps peak limited to below 10 µs followed by 0.6 amps peak limited to below 10 ms period. This will include transient current limits, single event turn-on and operational mode changes.

3.4.1.7 Input Voltage Transients

The VSS camera shall sustain single event switching transients of +/-120 % on its input 5.5 Vdc power line.

3.4.1.8 Power Interruption

The VSS camera shall survive the sudden removal and subsequent resumption of input power without sustaining any permanent damage and/or performance degradation when in use.

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3.4.1.9 Input Under-Voltage

The VSS camera shall survive a sustained under-voltage condition on its input power (0 Vdc to

4.5 Vdc) without sustaining any permanent damage.

3.4.1.10 Internal Protection

The VSS camera power design shall protect itself against the following conditions:

a) Any internal sustained overload [120% to 150% of nominal load] conditions

b) Any internal sustained short circuit conditions

c) Any inrush current conditions observed during the start up or during any other normal/abnormal operational conditions observed. This includes all possible worst-case conditions of input line/output load and temperature conditions standalone or combined

3.4.1.11 Initial State

Upon the application of power, the VSS camera shall power up into a known and repeatable state that shall be defined in the electrical ICD.

Note: The Government expresses the desire to work with the Contractor to define the exact power-up parameters of the camera’s focal plane array (e.g. default integration time, frame rate, frame size, etc.)

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3.4.2 Video Interface

3.4.2.1 Video Physical Layer

The VSS camera shall employ Multipoint Low-Voltage Differential Signaling, M-LVDS

(LVDM / Bus-LVDS), as the physical layer for the video data.

3.4.2.2 Data Protocol

The VSS camera may utilize up to four (4) twisted pairs to enable the video data transmission protocol of the Contractor’s choosing. This total of four (4) twisted pairs can be allocated between data, clock and sync lines as deemed necessary by the Contractor to implement the protocol of their choosing. The Contractor is not required to utilize all four (4) twisted pairs if they are not deemed necessary.

3.4.2.3 Data Bandwidth Limit

The VSS camera shall be configured in such a manner that either by native design, or by manual command, the maximum allowable bandwidth down any given twisted pair shall not exceed 50

Mbps.

Note: Higher data rates are acceptable, however there shall be at least one operational mode of the VSS camera that adheres to this bandwidth limit while meeting all other requirements in this document.

3.4.2.4 Data Skew

The VSS camera shall have less than or equal to two (2) nanoseconds of data skew on any given data channel, referenced to its rising or falling clock edge while operating at the camera’s nominal clock frequency.

3.4.2.5 Clock Jitter

The VSS camera shall have (a) less than or equal to one (1) nanosecond peak to peak, cycle to cycle clock jitter and (b) less than or equal to one (1) nanosecond peak to peak of clock jitter between rising and falling edges within the clock cycle, while operating at the camera’s nominal clock frequency.

3.4.2.6 Video Data Format

The VSS camera shall output the raw Bayer pattern data from the image sensor via the video interface in its default operational mode.

Note: If an internal demosaicing algorithm is utilized internal to the VSS camera, a manual command to disable it shall be included in the camera design.

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3.4.2.7 Image Latency

The duration between the end of integration of a single frame and the last bit of that frame leaving the VSS camera shall not exceed 50ms.

3.4.2.8 Image Latency Jitter

The image latency shall not vary by more than 5ms.

3.4.2.9 Demosaicing Algorithm

3.4.2.9.1 Ground Support Equipment Implementation

The demosaicing algorithm that interpolates color imagery from the raw Bayer pattern data shall reside in the VSS camera Ground Support Equipment (GSE).

3.4.2.9.2 Flight Implementation

The demosaicing algorithm that interpolates color imagery from the raw Bayer pattern data shall be made available to the Government in one of the following forms:

a) Scientific Journal Reference: If the Contractor’s demosaicing algorithm is based upon an open source algorithm that is readily available in scientific literature, then the algorithm type and referenced journal article shall be provided.

b) Algorithm Description Document (ADD): If the demosaicing algorithm is a unique creation of the Contractor, then an ADD that details the mathematics and implementation of the demosaicing algorithm is required.

Note: Government access to the demosaicing source code software / firmware is not required.

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3.4.3 Command Interface

3.4.3.1 Command Ability

The VSS camera shall accept commands to vary critical internal settings of the camera while the camera is in an active video mode.

3.4.3.2 Command Physical Layer

The VSS camera shall employ Low-Voltage Differential Signaling (LVDS) via a single (1) twisted pair as the physical layer for the command interface.

3.4.3.3 Command Transmission Integrity

The VSS camera shall utilize Cyclic Redundancy Check (CRC) protocols on the command line to detect errors during command transmit and receive.

3.4.3.4 Reset

The VSS camera shall utilize a reset command that causes the processor to start over at the beginning of the boot sequence as if power had been cycled off and on. All parameters shall be reinitialized to their default values when this command is executed.

3.4.3.5 Test Pattern

The VSS camera shall by command, output a test pattern image to verify the functionality of the data interfaces, integrity of the transmission line medium, and image format interpretation.

3.4.3.5.1 Test Pattern Verification

The contractor shall provide the Government with the expected format and content of the VSS camera test pattern image.

3.4.3.6 Valid Command Protection

No sequence or combination of valid commands shall damage the VSS camera, reduce its life expectancy, or cause any malfunction.

3.4.3.7 Valid Command Counter

(a) The VSS camera shall employ an internal command counter that tracks the number of commands that the camera has received and successfully executed. (b) The command counter shall increment by a value of one (1) for each successful command received / executed.

3.4.3.8 Invalid Commands

The VSS camera shall trigger an error flag that is reported in the camera telemetry when an invalid command is received by the camera.

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3.4.3.9 No Operation Command

The VSS camera shall accept a no-operation (no-op) command, the execution of which results in no change in the camera’s operational status other than the command counter incrementing by a value of one (1).

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3.4.4 Telemetry Interface

3.4.4.1 Telemetry Ability

The VSS camera shall output the heath and status of all critical components, including temperature(s) of the detector, necessary to determine the general overall state and configuration of the system.

3.4.4.2 Telemetry Physical Layer

The VSS camera shall employ Low-Voltage Differential Signaling (LVDS) via a single (1) twisted pair as the physical layer for telemetry interface.

3.4.4.3 Telemetry Update Rate

The VSS camera shall automatically output the health and status telemetry at a rate that is synchronous with the camera’s frame rate such that telemetry values can be correlated to a single camera frame.

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3.4.5 General Electrical Requirements

3.4.5.1 Interface Control Document

The Contractor shall provide an electrical Interface Control Document (ICD) that includes at a minimum, the following content:

a) Overall definition of the VSS camera system, it’s modes of operations, and command sequence to achieve an active operational state

b) Definition, part numbers and pin outs of the various electrical connectors

c) Power draw under different operating modes while powered at minimum, maximum and nominal voltages

d) Grounding Scheme

e) The format and structuring of any data / command / telemetry / interfaces

f) Full set of commands, their syntax, their variables, and any applicable calibration coefficients capable of being input to the system

3.4.5.2 Input Safety

The presence or absence of any combination of the input signals applied in any sequence shall not damage the VSS camera, reduce its life expectancy, or cause any malfunction, either when the unit is powered or when it is not.

3.4.5.3 Connector Covers / Connector Savers

The Contractor shall provide flight-approved RF, electrostatic discharge control covers and connector savers for all of the VSS camera connectors.

3.4.5.4 Isolation Requirements

a) The VSS camera shall provide a minimum of 1 MΩ isolation between two independent power feeds (includes supply and return lines).

b) All of the grounding and power returns shall be isolated in the VSS camera design.

c) The returns from different power output circuits shall be isolated from each other.

d) The returns of input (primary) and output (secondary) side shall be isolated from each other.

3.4.5.5 Internal Fusing / Over Current Protection

There shall be no internal fusing in the VSS camera. If required, components may use resettable solid-state switches for over-current protection.

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3.4.5.6 Test / Debug Inputs

If required, the VSS camera test and/or debug interfaces shall follow the test signal rules below:

a) VSS camera power shall not be applied or accessed at or through a test connector

b) Test connectors shall meet the same specifications as any flight connectors

c) Circuits wired to the test connectors shall be designed to prevent damage due to an external short, test equipment malfunction or electrostatic discharge (ESD) event.

d) Test / debug interfaces are not considered part of the flight interface. As such, the VSS camera shall be able to perform nominally during spaceflight without access to these interfaces

3.4.5.7 Grounding

All services within the VSS camera shall be referenced to a common ground. Mating surfaces shall be free from nonconductive finishes and shall maximize contact surface area. Connector shells shall be electrically bonded to the chassis through an electrical resistance not exceeding

2.5 mΩ. Unless specifically approved by the Government, the component’s ground connection shall be made through its mounting interface.

3.4.5.8 External Surface and Differential Charging Mitigation

a) The external conductive surfaces of the VSS camera shall be grounded with less than a 1

MΩ resistance to the chassis mount.

b) Partially conductive surfaces (e.g., paints, coatings) applied over a conductive substrate shall have a Resistivity- thickness product

Equation 3-1 𝒓𝒕 < 𝟐𝑬𝟗 𝒐𝒉𝒎 − 𝒄𝒎𝟐 where r is the material resistivity in ohm-centimeters and t is the material thickness in centimeters.

c) Partially conductive surfaces/coating applied over a dielectric (and grounded at the edges) material shall have material resistivity such that;

Equation 3-2 𝒓𝒉𝟐 𝒕 ≤ 𝟒𝑬𝟗 𝒐𝒉𝒎 − 𝒄𝒎𝟐 where r is the material resistivity in ohm-centimeters, h is the greatest distance on a surface to a ground point, in centimeters and t is the material thickness in centimeters.

d) Any partially conductive surfaces applied over a non-conductive (dielectric) substrate shall be grounded at the edges and shall have a surface resistivity of less than 10E9 ohms per square.

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3.4.5.9 Surface Conductivity and External Discharge Protection

a) A surface charging analysis shall be performed including an inventory of all surface materials and their resistivity and thickness.

b) An inventory shall include triple points, floating conductors and multiple conductor element components.

c) All of the camera external surfaces > 6 cm2 (0.9375 in2) shall be conductive with a surface resistivity of less than 10E9 Ω/sq. (at vacuum conditions and the minimum expected operating temperature).

d) The VSS camera external surfaces with surface resistivity greater than 10E9 Ω /sq. (at vacuum conditions and the minimum expected operating temperature) shall be limited to

60 cm2 (9.30 in2) total, per any 1 m2 (1550 in2) area, with no single surface area with surface resistivity greater than 10E9 Ω /sq. greater than 6 cm2 (0.9375 in2).

e) The following requirements shall apply to VSS camera Lens and Optics exposed to space environment.

1. Provide conductive coating with resistivity < 109 ohm/sq. (at vacuum and minimum operating temperature conditions).

2. Ground the conductive coating around the edges with a grounding impedance of <

1Mohm.

3. Protect the victim circuits against possibility of any ESD discharges by filtering and/or transient voltage suppression techniques.

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3.4.5.10 Internal Charging

a) The component design of the VSS camera shall prevent internal charging/discharging effects that can damage the internal components or disrupt operations.

b) Internal charging effects shall be controlled by shielding all electronics elements with greater than or equal to 110 mil aluminum equivalent shield thickness so that the internal charging rate is benign.

c) Internal dielectric materials of the VSS camera shall have a bulk resistivity less than

10E9 ohms-cm, or a surface resistivity less than 10E9 ohms per square.

d) The VSS camera shall ground all of its internal floating conductors with surface area > 1 in2 with less than 10E9 ohm resistance (at the minimum expected operating temperature and in vacuum after bakeout).

e) All exceptions or deviations to these requirements shall be assessed and approved by the

Government

Note: Further investigation into these effects and mitigations of internal charging can be found in the NASA document, Avoiding Problems Caused by Spacecraft On-Orbit Internal Charging

Effects, NASA-HDBK-4002.

3.4.5.11 Dielectric Strength

a) To minimize the electrical discharge caused by the internal charging of dielectrics, the strength of the electrical field in the dielectrics should be kept less than 10E6 V/m.

b) At a junction point between a conducting surface and dielectric surface, a potential difference shall be limited to 100 volt.

c) In order to limit differential voltage, a maximum current density of 10 nA/cm2 through the dielectric shall be used to calculate the maximum resistivity of the dielectric materials.

3.4.5.12 Insulation Resistance

When high-resistance material surfaces need to have higher insulation values, charging analysis of high-resistance material surfaces shall be conducted to show that the electrical potential of the insulators…