L1 Series COR SPEC Rev 11-8-23.docx

L1SERIES-COR-REQ-0018, Revision - Effective Date:

Space Weather (SW) Next L1 Series, Code 491.0 L1SERIES-COR-REQ-0018, Revision -

Space Weather (SW) Next L1 Series SW L1 Coronagraph Requirement Specification (CSPEC)

SWO CMO

October 19, 2023

DRAFT

U.S. Department of Commerce (DOC) National Oceanic and Atmospheric Administration (NOAA) NOAA Satellite and Information Service (NESDIS)

National Aeronautics and Space Administration (NASA) Check https://ipdtdms.gsfc.nasa.gov/frontmenu_dsp.cfm to verify that this is the correct version prior to use.

SW L1 Coronagraph Requirement Specification (CSPEC) Review/Signature/Approval Page

Prepared by:

Mark Edison Systems Engineer

Date

SWO L1 Series NASA GSFC, Code 493

Reviewed by:

Charles “Hudson” Delee Systems Engineer

Date

SWO L1 Series

Approved by:

Timothy Van Sant L1 Series Project Manager

Date

SWO L1 Series

Electronic Approval available on-line at: IPD TDMS - Instruments Project Division TDMS (nasa.gov)

Preface

This document is under SWO Program configuration control. Once this document is approved, SWO approved changes are handled in accordance with Class I and Class II change control requirements as described in the SWO Configuration Management Procedure, and changes to this document shall be made by complete revision.

In this plan, all mandatory actions (i.e., requirements) are denoted by statements containing the term “shall.” The terms “may” or “can” denote discretionary privilege or permission; “should” denotes a good practice and is recommended but not required; “will” denotes expected outcome; and “are/is” denotes descriptive material.

Any questions should be addressed to:

SWO Configuration Management Office

NASA/GSFC

Code 490.0 Greenbelt, MD 20771

Change History Log Change History Log will be provided by CM prior to release

Deviations/Waivers Record

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Table of TBCs/TBDs/TBRs/TBSs

The L1 SERIES spacecraft will monitor up to six (TBR) analog instrument health and safety parameters defined by the Coronagraph contractor and command the Coronagraph into safe mode when any of those key values have been exceeded.

The Coronagraph +XCSRF axis is aligned with the instrument line of sight, the +YCRSF axis is perpendicular with the instrument mounting plane and the +ZCSRF axis completes the triad.

1. Test methods can be in accordance with the latest version of the Goddard Environmental Verification Specification (GEVS), MIL-STD-461C/462 as approved by the Project prior to commencement of testing

2. Guidelines for defining magnetic requirements are provided in "The Design, Construction and Test of Magnetically Clean Spacecraft - A Practical Guide (Mario H. Acuna)". TBD.

3. Default limit. The limit will be updated when all reveivers, including instruments, if any, have been defined.

4. Default limit. The limit will be updated when all transmitters, including launch vehicle, have been defined.

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Table of Contents

List of Figures

List of Tables

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Introduction General Information Scope This specification describes the performance and electrical, mechanical, environmental, and verification testing requirements for a space-qualified Coronagraph Instrument for the Space Weather Next Lagrange 1 (L1 Series) Series Mission.

Applicable Documents CSPEC6: The following documents and drawings in effect on the day this specification was signed shall apply to the fabrication and to the electrical, mechanical, and environmental requirements of the Coronagraph to the extent specified herein. In the event of conflict between this specification and any referenced document, this specification will govern, except for the L1 Series Coronagraph Statement of Work (L1SERIES-COR-SOW-0006), in which case the Statement of Work takes precedence.

The following is a list of the applicable specifications and publications.

Table 1 Applicable Documents (TBR)

Contract Description Coronagraph Description The Coronagraph instrument consists of a telescope module, an electronics box and the associated interconnecting cables up to the spacecraft provided interface.

The Coronagraph contract includes the delivery of One (1) Engineering Development Unit (EDU) with representative spacecraft mechanical and electrical interfaces. Three (3) Flight Units, plus parts for 3 additional flight units to be procured concurrently, plus parts for a robust sparing philosophy; and a flight spare instrument philosophy to mitigate risk of issues identified late in the launch integration flow.

Ground Support Equipment Description The Coronagraph contract includes the delivery of (2) sets of the Electrical System Test Equipment (ESTE), (4) Coronagraph Emulators, (1) Flight Software Development Environment (FSDE), and (1) One Ground Processing Development System (GPDS). Additionally, Mechanical Ground Support Equipment (MGSE) such as lifting fixtures/handles, shipping containers, purge carts, drill templates, test fixtures, non-flight protective covers, etc. are included in the delivery. Electrical Ground Support Equipment includes, but is not limited to, test cables and break-out boxes.

The Coronagraph delivery includes the ground support equipment required to power and operate the Coronagraph at the vendor’s and spacecraft contractor’s facilities. The delivery also includes a standalone emulator that will interface to a spacecraft simulator for the purposes of interface testing, operations product development, and training.

Ground Support Equipment is necessary to operate the instrument during spacecraft testing. Supplying this equipment is considered part of the delivery for the instrument. More information is provided in the Contract Data Requirement List (CDRL).

Functional/Performance Requirments This section defines the functional and performance requirements for the Space Weather Next Lagrange 1 Series Coronagraph.

The requirements in this Specification pertain to the Coronagraph ‘system’, which may include all instrument hardware, software, and ground processing algorithms. The Coronagraph contractor is not responsible for the operational ground system, but certain specifications may require ground processing after collection but before data distribution, which the contractor is responsible for defining and developing.

Coronagraph Performance Requirements Scene Coverage CSPEC22: The Coronagraph shall capture radial coronal scenes from ≤ 3 RSun to ≥ 22 RSun (TBR-1).

CSPEC23: The Coronagraph shall capture the radial coronal scene with a ≥ 290° coverage satisfying all spatial and photometric requirements.

Rationale: The inner field of view represents a geometric cutoff, not a photometric cutoff, and does not account for spacecraft motions. The spatial range for the field of view ensures that a CME travelling at ~3000 km/s can have sufficient observations (with the cadence given in Section 4.1.6) to fit model parameters. The specification ensures at least three images for each CME observed, giving sufficient margin for determining the CME properties necessary for prediction. Note that the external occulter (EO) will vignette the coronal scene (reduce the A1 aperture that can view the coronal scene) and add to the image noise from the diffracted straylight. The angular scene coverage of 290° allows use of pylon(s) to support the occulter. The EO pylon(s) will vignette the coronal scene (reduce the A1 aperture that can view the coronal scene) and add to the image noise from the diffracted straylight off of the EO pylon edge and reflected straylight off of the aft face of the pylon(s). The impact of the EO pylon(s) on the vignetting and straylight will decrease with the polar angle from the center of any EO pylon(s). Therefore, it is recognized the spatial and photometric requirements will have localized effects near these instrument features.

Spatial Resolution CSPEC26: The Coronagraph shall capture coronal images with spatial resolution ≤ 70.0 arcsec (TBR-2) over the un-occulted field of view.

Rationale: The image spatial resolution is defined as the average of the optical spatial resolution in the sagittal and tangential planes of the optical system. The instrument spatial resolution applies to an image acquired under nominal pointing conditions (with no boresight jitter or pointed windowed stability during the averaged image acquisition time). The spatial resolution is defined as the distance, in arcsec, between two point-sources of equal brightness located at infinity. The relative intensity between the peaks of the imaged sources (100% intensity) and the intensity at the mid-point between the peaks is 90% or less.

Measurement Range CSPEC29: The Coronagraph shall capture coronal white light imagery with intensity of 1×10-11 BSun to 1×10-8 BSun (TBR-3).

Rationale: The coronagraph’s dynamic range shall be such that the expected signal of the F + K corona, the residual straylight, and the CME all as modulated by the vignetting will be covered over the entire field of view. Bsun (or B0) is the surface brightness of the solar disk, which is an extended source. It is equivalent to the observed flux density per solid angle.

Accuracy CSPEC31: The Coronagraph shall have photometric accuracy for the corona image of ≤ 10% in mean solar brightness (TBR-4).

Rationale: Setting absolute photometric accuracy, i.e. calibration, on the observed scene allows for determination of CME mass. Much of the image noise in the K corona image is shot noise with a Poisson distribution for the electrons collected at each pixel based on the total brightness of the instrumental straylight, the coronal scene, vignetting, and the detector dark current. The estimation error over a block of pixels dominated by Poisson statistical noise can be reduced by averaging over this block of pixels if the source brightness is not varying greatly over this pixel block.

Unobstructed Field of View (UFOV) CSPEC33: The Coronagraph shall allow for an unobstructed field of view of no more than 50 deg (TBR-5) half cone angle.

Rationale: Allows for glint or other interference of spacecraft structures at angles larger than this.

Refresh Rate and Latency CSPEC35: The Coronagraph shall produce an image during nominal operations at a refresh rate of every 15 minutes or less (TBR-6).

CSPEC36: The Coronagraph shall produce an image with a latency of 13 minutes after end of image acquisition (TBR-7).

Rationale: The specifications ensure at least three images for each CME observed, giving sufficient margin for determining the CME properties necessary for prediction. Note that the Coronagraph instrument latency is only one component of the end-to-end latency budget. Total system data latency— from image acquisition completion at the spacecraft to SWPC’s generation of corresponding Level 3 data products—is 15 minutes; the 13 minutes allocated for the instrument includes data processing time (on-board, on the ground, or a combination) and data transfer with rates specified in Section 4.2.6. The latency value is set by the SWPC forecasters’ time needed for analyzing the images and by the cadence of the center’s real-time operational models.

Detector Well Depth CSPEC38: The Coronagraph instrument exposure time shall be such that total brightness measurement in electrons does not exceed 95% full well of detector.

Rationale: Ensure observations fit with refresh rate and latency requirements.

Operations during Storm conditions CSPEC39: The coronagraph shall provide data during a S4 (solar radiation) storm event.

Rationale: To fulfill its mission of providing the observational data needed for the SWPC Forecast Office to issue solar storm warnings and watches, the SWFO Program must be able to make observations during the most intense reasonably expected solar radiation storms and solar flares. Severe space weather of all types can occur at the same time. Previous non-operational missions such as ACE and SOHO have been significantly degraded and unable to make observations at times during the most intense solar storms and flares.

The solar radiation storm intensity scale goes from S1 to S5 (https://www.swpc.noaa.gov/noaascales-explanation). A solar storm of intensity S5 has never been observed, but is believed to be physically possible. A solar storm intensity of S4 includes storms where the 10 MeV integral proton fluxes reach at least 1x104 proton flux units (PFU) but do not reach 1x105 PFU.

Resource Allocations Mass Allocation CSPEC41: The Coronagraph instrument, including the imaging module, power supply box, intra-instrument harness, and thermal blankets, shall have a combined mass of ≤ 29.0 kg (includes margin).

CSPEC42: The Coronagraph instrument mass margin shall comply with GSFC-STD-1000H Rule 1.06.

Physical Envelope CSPEC43: The Coronagraph instrument volume (length*width*height), including the sensor unit (TBD-1), electronics box (TBD-2), mounts, sensor standoff bracket (if required), instra-instrument harness, thermal blankets, and connectors, for both stowed and operational configurations shall have dimensions that do not exceed a total volume of TBD-3 cm3. These dimensions pertain to both static and dynamic envelopes of the instrument.

CSPEC44: The Coronagraph maximum instrument volume during deployment of mechanisms shall have dimensions that do not exceed a total volume of TBD-4 cm3 Operational Power Allocation CSPEC46: The Coronagraph instrument average operational power shall not exceed 29 Watts when averaged over any 15-minute period.

Peak Operational Power CSPEC48: The Coronagraph instrument shall have a peak (instantaneous) power consumption of less than or equal to TBD-5 for a duration of 60 seconds.

Survival Heater Power CSPEC50: The Coronagraph instrument survival heater power shall not exceed TBD-6 Watts when averaged over any 60-minute period.

Telemetry CSPEC52: The Coronagraph instrument total data rate, including all overhead associated with Consultative Committee for Space Data Systems (CCSDS) packetization by the instrument at the spacecraft interface, shall not exceed 140 kbps averaged over 5 seconds.

Transient Magnetic Field CSPEC54: The Coronagraph instrument shall limit varying magnetic field less than 5 Hz to less than 4 nT zero-to-peak in any axis 1 meter from any face of the unit for any operating mode and changing configurations.

Static Magnetic Field CSPEC56: The Coronagraph instrument shall limit the static magnetic field to less than 40 nT in any axis 1 meter from any face of the unit for any operating mode.

Coronagraph Operating Modes Mode Transitions CSPEC59: The Coronagraph instrument shall transition from the current mode to any other mode without causing damage to itself.

Deterministic Power on Configuration CSPEC61: The Coronagraph instrument shall initialize into a predetermined configuration.

Safe Mode Provision of Safe Mode CSPEC64: The Coronagraph instrument shall provide a Safe Mode. Safe mode is an operating mode of the instrument during which all non-essential subsystems are shut down and only essential functions are active. Safe mode represents a configuration in which the instrument is thermally, mechanically, and optically “safe” without receiving commands from the Spacecraft.

CSPEC65: The Coronagraph instrument shall be capable of remaining in a safe configuration for at least 168 hours without ground intervention.

Entry Into Safe Mode CSPEC67: The Coronagraph instrument shall enter Safe Mode upon detection of internal faults that can cause damage to the instrument.

The L1 SERIES spacecraft will monitor up to six (TBR) analog instrument health and safety parameters defined by the Coronagraph contractor and command the Coronagraph into safe mode when any of those key values have been exceeded.

Normal Operational Mode CSPEC70: In normal operational mode, the Coronagraph instrument shall be in a fully functional configuration in which designed measurements are made in accordance with the performance requirements listed in section 4.1 of this document and are available to be sent to the spacecraft for downlink.

On-Orbit Operations CSPEC72: The Coronagraph instrument shall operate normally, within specification, while flying aboard a 3-axis stabilized spacecraft with orbital limit constraints as stated in this specification.

Station Keeping CSPEC74: The Coronagraph instrument shall continuously operate during all spacecraft maneuvers.

CSPEC75: The instrument shall meet all performance requirements within 300 seconds (TBR-9) after the spacecraft interface has returned to being within specification following spacecraft maneuvers.

Instrument Data Availability CSPEC16: The Coronagraph instrument shall have a 99.9 % (TBR-8) probability of operating continuously on-orbit during nominal observation mode (which excludes non-Coronagraph related Spacecraft Safe Holds, instrument calibrations and storm conditions).

CSPEC17: The Coronagraph Instrument shall limit on-orbit calibrations to no more than four (4) calibrations per year with each calibration lasting no more than 30 minutes.

CSPEC18: The Coronagraph instrument shall be capable of maintaining nominal observation mode without ground interaction for a minimum of four days.

CSPEC19: The instrument shall ensure there are no gaps in HAP data due to planned instrument events during NWS-declared Critical Space Weather Days.

Rationale: Once a Critical Space Weather Day is declared by NWS it is expected that any pre-planned instrument activities (e.g., calibration maneuvers) will have the flexibility to be re-scheduled without impacting instrument performance. The expected cadence and duration of NWS-declared Critical Space Weather Days is (TBR).

CSPEC20: The instrument shall provide a 99% (TBR-10) or greater probability of providing all of the instrument's HAP data during S4 class solar radiation storms or solar flare conditions including class X50, verifying through analysis using the “Worst Week” October 1989 model in CREME96 or equivalent.

Rationale: the CREME96 model includes the October 1989 solar particle event worst week model that conservatively bounds the single event effects environment in S4 and X50 solar events. It is expected that the probability of occurrence of outages as well as Bit Error Rates (BER) due to SEE will be used in the analysis that verifies this probability (CSPEC323 and CSPEC328 have been deleted and are being replaced with this requirement). Further definition of the worst week model can be found here: https://creme.isde.vanderbilt.edu/CREME-MC/help/solar-energetic-particle-environment.

Power The spacecraft will provide a power feed to the Coronagraph Instrument operational electronics.

The spacecraft will provide a power feed for the Coronagraph Instrument survival heaters.

Voltage Range CSPEC80: The Coronagraph instrument shall operate over the bus voltage range of 30 +/-4 VDC at the primary power inputs during all normal mission phases and for all expected load conditions (except when turned off).

Abnormal Voltages CSPEC82: The Coronagraph instrument shall survive without performance degradation after indefinite exposure to an anomalous voltage range of 0 to +40 VDC.

Power Transients The Coronagraph instrument shall meet its performance requirements in the presence of transients specified in MIL-STD-461F, Figure CS115-1 and Figure CS116-2.

Sudden Removal of Power CSPEC86: The Coronagraph instrument shall meet its performance requirements without degradation after exposure to an abrupt, unannounced removal of power.

Over-Current Protection The Coronagraph instrument does not use non-resetting over-current protection (i.e., fuses) internal to the unit Primary Power Return Ground CSPEC90: The Coronagraph instrument shall provide a dedicated Primary Power return in the same connector as the primary power.

Turn On Current Transients CSPEC92: The Coronagraph instrument shall limit any change in operational power current at any time (including initial power turn-on) to no more than 0.2A/µs. (TBR) Electrical Grounding Primary Power DC Isolation CSPEC95: The Coronagraph primary power interfaces, primary power and primary power returns, shall be isolated from the unit chassis by a DC resistance of greater than or equal to 10 Megaohms.

Survival Power Isolation CSPEC97: The Coronagraph survival heater power interfaces shall be isolated from the unit chassis by a DC resistance of greater than or equal to 10 Megaohms.

Rationale: Returning the instrument survival heater power returns to the spacecraft single point ground and isolating the survival heater power returns from the instrument chassis helps control common mode noise current and minimize magnetic field effects due to ground loops.

Internally Generated Secondary to Primary DC Isolation CSPEC99: Secondary power inputs shall be isolated from primary power by a DC resistance of greater than 10 Megaohms.

Rationale: Isolating the instrument secondary power returns from the instrument primary power returns helps control common mode noise currents and minimizes magnetic field effects due to ground loops.

Internally Generated Secondary Return CSPEC101: The Coronagraph shall reference its secondary returns (power and signal grounds) to the unit chassis ground.

Rationale: NASA-HDBK-4001 ELECTRICAL GROUNDING ARCHITECTURE FOR UNMANNED SPACECRAFT Mechanical Contact Resistance CSPEC103: The DC resistance of the mechanical contact between two conductive mating mechanical surfaces (internal to the unit) shall be less than or equal to 2.5 mΩ DC resistance.

Rationale: Low resistance contacts are essential for maintaining a zero potential ground.

Grounding CSPEC105: The DC resistance between the Mag Electronics Unit chassis and the observatory chassis shall be ≤ 2.5 milliohms.

Rationale: Low resistance contact between instrument chassis to spacecraft structure is essential for maintaining a zero potential ground.

CSPEC106: The Coronagraph shall provide a ground lug for a grounding strap to be attached from the Coronagraph Electronics Unit chassis for connection to the spacecraft conductive structure.

Rationale: This provides a method/location for tying the instrument ground to the spacecraft conductive structure.

CSPEC107: The grounding lug location on the Cornagraph Electronics Unit chassis or the tie points in contact with the ground strap shall be defined in the MICD. The ground lug contact area must remain free of any material finish that may affect the reliability of the ground connection and will be shown in the MICD.

Connector DC Resistance CSPEC109: Coronagraph connector backshells shall be electrically connected to Electronics Unit chassis with a DC resistance ≤ 2.5 mΩ.

Rationale: Low resistance contact between instrument chassis to spacecraft structure is essential for maintaining a zero potential ground.

Signal and Data Interfaces Passive Analog Telemetry CSPEC112: The Coronagraph shall utilize no more than three analog signals to monitor critical temperature points when the Coronagraph is powered off.

Rationale: Common best practices for on-orbit operations deems that the Spacecraft will be able to monitor health and safety of the instrument if the instrument is in any configuration other than the normal operational configuration, e.g. safe or survival mode. Six signals is also deemed reasonable given the complexity of the instrument.

Data Signal Interface CSPEC114: The Coronagraph Instrument shall interface for data transfer to or from the spacecraft by SpaceWire (ECSS-E-ST-50-12C-rev.1) data bus.

Rationale: SpaceWire is the preferred standard high-rate data interface.

The spacecraft will provide two data signal interface feeds to the Coronagraph Electronics Unit for command and telemetry. The spacecraft will also provide an interface line for a Pulse Per Second (PPS).

Telemetry Source Packet Format CSPEC117: The Coronagraph shall transfer all data to the spacecraft using the CCSDS 133.0-B-1 Section 4.1 Protocol Data Unit definition shown in the Telemetry Source Packet Definition Figure 1.

Rationale: Use of CCSDS standards simplifies command and telemetry data handling system and interface design.

Figure 1 Telemetry Source Packet Definition CSPEC120: The Coronagraph telemetry Source packets shall be variable length with a maximum data zone of 8192 octets including Secondary Header.

Rationale: CCSDS 133.0-B-1 Space Packet Protocol, Blue Book, Issue 1, September 2003 CSPEC121: The Coronagraph shall set the telemetry source packet Secondary Header Flag to the value 1.

Rationale: CCSDS 133.0-B-1 Space Packet Protocol, Blue Book, Issue 1, September 2003 CSPEC122: The Coronagraph shall set the Telemetry Source Packet Sequence Flags to the value of 11.

Note: Segmentation services are not permitted.

Rationale: CCSDS 133.0-B-1 Space Packet Protocol, Blue Book, Issue 1, September 2003 CSPEC123: The Coronagraph shall set the Telemetry Source Packet Time Code per CCSDS 301.B-4 Time Code Formats, Day Segmented format in the Time Code Format Figure 2.

Rationale: CCSDS is a data format interface standard developed by NASA to create commonality to simplify data processing and routing.

Figure 2 Time Code Format Note: The P-Field is implied and not included in the actual time message.

The Spacecraft will maintain a continuous time system on-board that can be related to UTC time on the ground.

Command Source Packet Format CSPEC130: The Coronagraph shall receive all data from the spacecraft formatted per CCSDS 133.0-B-1 Section 4.1 Protocol Data Unit definition shown in the Command Source Packet Definition Figure 3.

Rationale: CCSDS is a data format interface standard developed by NASA to create commonality to simplify data processing and routing.

INSERT FIGURE

Figure 3 Command Source Packet CSPEC133: The Coronagraph command Source packets shall be variable length with a maximum data zone of 8192 octets.

Rationale: CCSDS 133.0-B-1 Space Packet Protocol, Blue Book, Issue 1, September 2003 CSPEC134: The Coronagraph shall receive Command Source Packet with Secondary Header Flag set to the value 0.

Rationale: CCSDS 133.0-B-1 Space Packet Protocol, Blue Book, Issue 1, September 2003 CSPEC135: The Coronagraph shall receive Command Source Packet with the Sequence Flags set to the value of 11.

Note: Segmentation services are not permitted.

Rationale: CCSDS 133.0-B-1 Space Packet Protocol, Blue Book, Issue 1, September 2003 Clock Signal Interface CSPEC137: The Coronagraph shall receive a Pulse Per Second (PPS) time pulse from spacecraft clock line by the interface defined in CSPEC114.

Rationale: TBD to allow for flexibility The Spacecraft will maintain Spacecraft time correlation to within +/- 0.95 sec of UTC and will provide the Coronagraph a 1 PPS with a time code message.

The spacecraft will provide a clock interface feed to the Coronagraph Electronics Unit.

CSPEC140: The Coronagraph shall receive from the spacecraft a time code message on the data line as defined in Spacecraft Time Message Packet Figure 4. The time code message is the time applicable to receipt of the 1 PPS.

Rationale: CCSDS 133.0-B-1 Space Packet Protocol, Blue Book, Issue 1, September 2003

Figure 4 Spacecraft Time Message Packet Figure Command and Housekeeping telemetry CSPEC144: The Coronagraph instrument shall provide command and housekeeping telemetry functions in all powered modes.

Rationale: Housekeeping telemetry are data required to monitor instrument operation, health, and safety. Command functions may be required to maintain the health and safety of the instrument.

Commands for Autonomous Functions CSPEC146: The Coronagraph shall execute commands to individually enable and disable each autonomous function.

Rationale: Allows flexibility to maintain the health and safety of the instrument during on-orbit operations.

Limits and Triggers CSPEC148: The Coronagraph autonomous limits and triggers shall be changeable by command.

Rationale: Allows flexibility to maintain the health and safety of the instrument during on-orbit operations.

On-Board Processor Reset CSPEC150: The Coronagraph On-Board Processor shall be reset by command.

Rationale: Common best practices dictate this capability for on-orbit anomaly troubleshooting, e.g. to terminate hung processes.

CSPEC151: An autonomous power-on reset occurrence shall be unambiguously identifiable via telemetry.

Note: This does not imply real-time telemetry as the reset is occurring.

Rationale: Common best practices dictate this capability for on-orbit anomaly troubleshooting Micro-switches CSPEC153: Micro-switches shall be used for information only and not used to initiate on-board autonomous activity or as an on-board interlock.

Rationale: Common best practices dictate this capability for on-orbit anomaly troubleshooting. Micro-switches are not reliable enough for autonomous actions.

Flight Software Flight Load Non-volatile Memory CSPEC156: The Coronagraph flight software image shall be contained in its entirety in non-volatile memory.

Rationale: Allows for power-cycling without loss of the stored flight software image.

Software Updates CSPEC158: The flight software modules shall be reprogrammable.

Rationale: Provides flexibility should operational changes be required following an anomaly, as the instrument ages, etc.

Software Table Updates CSPEC160: Instrument configuration data (e.g. Table Loads or Configuration Parameters) shall be reprogrammable during integration and test phases and on-orbit without computer restart.

Rationale: Common best practices dictate this capability to avoid unnecessary power cycles of the instrument.

CSPEC161: Modified instrument configuration data (e.g. Table Loads or Configuration Parameters) shall be committed to operational use by ground command.

Rationale: Common best practice to ensure “a person in the loop” before making a configuration change.

Flexibility and Ease of Software Modification CSPEC163: The Coronagraph flight software shall be deterministic in terms of scheduling and prioritization of critical processing tasks to ensure their timely completion.

Rationale: To ensure that a critical task gets executed in the intended timeframe.

CSPEC164: Instrument configuration data (e.g. Table Loads or Configuration Parameters) shall be referenced such that data can be loaded and dumped by the ground without reference to memory address.

Rationale: Common best practices dictates this capability for ease of operation and to reduce risk of loading to the wrong memory address.

CSPEC165: The definition of instrument commands within the ground database (excluding memory diagnostic/load commands) shall not be dependent on physical memory addresses within the flight software.

Rationale: To avoid the need to rebuild the command and telemetry database every time the flight software is recompiled; modifying the code results in address changes leading to command changes and then re-testing commands.

Version Identifiers CSPEC167: The Coronagraph software and firmware versions shall each have an internal identifier (embedded in the executive program) that can be included in the instrument engineering data.

Rationale: Common best practice to ensure that knowledge of version is always accessible.

CSPEC168: This software identifier shall be configuration management controlled.

Rationale: Common best practice.

Warm Restart CSPEC170: The Coronagraph flight software shall provide a restart by command with preservation of instrument configuration data and memory tables.

Memory Tests CSPEC172: The Coronagraph flight software shall provide a mechanism to verify the contents of all memory areas.

Rationale: Common best practice.

Memory Dump CSPEC174: The Coronagraph flight software, and associated on-board computer hardware, shall provide the capability to dump any memory location.

Rationale: Common best practice.

CSPEC175: The flight software memory dump capability shall not disturb normal operations and instrument data processing.

Rationale: Common best practice.

Fault Detection and Correction Control CSPEC177: If applicable, Coronagraph shall provide the capability to enable and disable any internal Fault Detection and Correction (FDC) features.

Rationale: Allows flexibility in the on-orbit operations.

Health and Safety Monitoring CSPEC179: The Coronagraph flight software shall provide health and safety monitoring, including memory checksum and watchdog timer.

Rationale: Common best practice for maintaining health and safety of the instrument.

Physical Requirements Interface and Design Units and Exclusions CSPEC182: The contractor shall use metric units to design the instrument and for developing interfaces with the spacecraft including any drawings, documents, models, except for the following cases:

· Heritage Component or unit: Components or units that has been previously qualified, or of similar design heritage, may be specified in English units where use of metric equivalents would lead to additional cost to the program.

· Fasteners: Although bolt patterns will be defined using metric dimensioning, use of English fasteners (with hole dimensioning and tolerancing) is permitted.

· Angular Measurement: Angular measurement may be expressed in degree of arc or in an appropriate subdivision of degree of arc such as second of arc (arc-sec) when advantageous to application.

Mass Properties Accuracy…