GSFC Common MEL Guidance.pdf

GSFC’s Master Equipment List (MEL) Guidance for Proposals version 8/20/21

Rows

• The grouping of rows should indicate physical sub-assemblies for the parametric Integration & Test (I&T) estimate to be accurate.

o For example, the optic, its frame and mount should be shown as an assembly because that unit is assembled and tested in that configuration before it is integrated at the next highest level. At the next highest level of integration, all the mounted optics and the optical bench would be integrated together (with anything else that’s on the optical bench) because the optics would be aligned and characterized at this stage.

o Items in an assembly should be indented (use Excel indent button) beneath the assembly row o At the assembly level, the total quantities should indicate how many copies of that (identical) assembly are required in the flight unit, and that row should show the mass of a single assembly and the mass of all flight assemblies

• The name of the component should also include a short description, unless the name itself is self-explanatory or obvious.

• Put backup flight units on same row with primary flight units, and note the number of each. This is in order that independent cost modelers consider the NRE savings.

• Do not use the data grouping function in Excel.

• Use the Excel indent button (one indent per level) as needed. Do not color code the text.

• Use the “Level” column to indicate sub-assembly grouping, where the rows are a breakdown of the next highest-level row. The Level column should correlate with the number of indentations.

• You must set up the summation formulas for desired sub-assembly grouping. The template does not do this because it does not know the groupings of the rows.

• Projects may choose to complete the MEL at the instrument or subsystem level for some elements, rather than at the component level. The rows are at the discretion of the project.

• Projects may decide whether to show TRL by element, by subsystem, or both.

Intro Columns

Level

• Use the “Level” column to indicate sub-assembly grouping, where the rows are a breakdown of the next highest-level row. This is also shown by indentation.

Name

• Name of the component, subassembly, element …

Mass and Unit Columns

Unit Mass

• Current Best Estimate (CBE) mass of a single unit

# Unit Columns

Cold (Backup) Units (not needed for proposals)

This column is used by the IDL, and may be hidden for a proposal. Cold Units and Hot Units are both flown, and the sum of units is the total Flight Units in Column D.

If an engineer is looking for savings, he/she may want to consider the need for the Cold Units.

Hot (Primary) Units (not needed for proposals)

This column is used by the IDL, and may be hidden for a proposal. Cold Units and Hot Units are both flown, and the sum of units is the total Flight Units in Column D.

Flight Units A Flight Unit is the actual unit that will be launched. It either undergoes protoflight testing if a qualification model has not been tested, or it undergoes flight acceptance testing if a qualification model has been successfully tested. This column includes everything planned for flight - the primary & backup flight units. This includes flight units that must fly to provide redundancy (ie. hot or cold spares). Note, if an ETU is planned and depended on to be a backup flight unit, it should be in this column.

Flight Spare A Flight Spare is a duplicate of a component, subsystem, or the entire Flight Unit.

Flight Spares are preassembled, tested and ready to swap with the corresponding Flight Unit, or they are spare flight-qualified parts ready for assembly and subsequent acceptance level testing when a need arises. Flight units that must fly to provide redundancy are not included in the flight spares column. The flight spares column includes hardware on the ground that is intended to replace a non-functioning flight item. Note, if an ETU is planned and depended on to be a flight spare, it should be in this column. Kitted parts should not be included here, but noted in the “Additional Information” column.

ETU / Qual Units (optional)

This total should include Engineering Test Units (ETUs) and Qual Units that will be fully flight qualified, but are not part of the total number of units planned for flight or spare. ETUs are qualification units that are tested to flight environmental levels, and can be flown if necessary; they can serve as flight spare units. Cost Modelers will cost the ETUs the same as flight spares, which is why the AO does not ask for this column. A separate ETU column may help with clarity. The "Additional Information" column can also be used. If your ETU should not be costed as a full flight spare, then discuss it in additional information or put it in the EM / EDU / Prototype column.

Engineering Model (EM) / Engineering Demonstration Unit

(EDU) /

Prototype

Engineering Model (EM) and Engineering Demonstration Unit (EDU) are generally different names for the same model. These engineering units are flight-like in terms of fit, form, and functionality. They are used to reduce risk, or perform life-testing on parts that can degrade over time and/or with use, provided flight-like parts are used for life test unit. A prototype is generally a non-flight like model that is used to demonstrate functionality early in the project. It is not used for environmental testing or flight qualification. Prototypes are included in the Engineering Model column. Breadboards are employed for lower TRL items (see NPR 7123 TRL definitions), and should be notated in the “Additional Information” column so that they are not inadvertently costed as an EDU / Prototype.

• Multiple quantities within a row should be used for identical units

• When there are identical units across different sub-assemblies or assemblies, this can be called out as well (use the “Additional Information” column, so that the NRE is only spent once) o The component name or identifier can include a reference to the subsequent location in the

MEL where another occurrence of the identical component exists (e.g. identical item is shown in line 293 or identical item is shown in the Mirror 2 Assembly) o Identical items must have identical mass and material composition.

o If an optic is physically identical but has a different optical coating applied, it is typically not shown as an identical component because it is modeled and characterized differently o The NRE cost will be spread across the multiple incidents of that item.

Total Mass

• This is required in the MEL per the AO template.

• It is a formula: Unit Mass multiplied by the Number of Flight Units

Power Columns The columns required in the Standard AO MEL template are nominal “total power”, “contingency”, and “total power with contingency”. Information regarding the power demand for each instrument operational mode including peak, average, and stand-by power is requested elsewhere in the proposal document. The Peak and Quiescent/standby power information is not required to be in the MEL. Delete these columns if not used.

Nominal Power

• This is required in the MEL per the AO template.

• Total power should be presented by mode, often in a separate table; usually it doesn’t make sense to simply sum the power values.

Peak Power

• This is not required in the MEL (per the AO template) but the information is required in the proposal.

• Peak may not make sense for all missions, and may be misleading because it should not be totaled, except possibly by mode. Delete these columns if not used.

Quiescent Power

• This is not required in the MEL (per the AO template) but the information is of interest in the proposal.

• Delete these columns if not used.

Additional Recommended MEL Columns

Quoted Price

• Provide the $ quoted unit price. The expectation is that the cost modelers will use this value (vs modeled value) for this element. If the unit price of the flight unit is different from the unit price of the EM/EDU/Prototype, be specific.

• A Quoted price will not be taken at its face value (by TMC modelers) unless the component is COTS (and TRL-9 or at least TRL-8).

• Add additional information about the quote in the Additional Information column of the MEL.

o Provide clarification between the unit price and price of the total number of units, including minimum buy requirements.

o Most AO’s have this requirement – use the Additional Information Column: For Quotes, the date of the quote, expiration date, and similar purchase history should be described.

Composition

• For Structural elements: List the materials in the part (eg. Titanium, Tin, Lead). If possible, list the % composition by mass for electrical, mechanical, thermal, and optical elements.

• For Electronics elements: Use this column as well as the Additional Information column to provide the information required by the AO.

o Most AO’s have this requirement - List each electronic board separately, identify the functionality of each board (either in the MEL or in the Mission Implementation section), and provide the speed the board will be running at. If proposing Field-Programmable Gate Arrays (FPGAs) or Application-Specific Integrated Circuits (ASICs), or Radio Frequency Integrated Circuits (RFICs), list the design size (in the appropriate sizing parameter such as logic cells, logic elements), the board the chip(s) will be integrated onto, and how much heritage will be used in the design.

Additional Information These potential items may be included, as appropriate:

• Additional information for specific subsystem components that improves cost accuracy:

o Electrical components: each printed circuit board (PCB) must be called out unless the entire enclosed assembly is commercially purchased List % analog vs. digital electronics (this would not apply if it was a backplane); if it is significant, the mass of the connectors can also be represented (e.g. 45% analog, 50% digital and 5% connector mass)

Call out programmable logic devices such as FPGAs, ASICs, and processors Call out on-board memory and capacity If it is not obvious from the board name/function, also call out if there are ADC or

DACs Reliability class of electronic parts (Class S, Class B, or Class D); note that electronics parts class is not the same as Mission class (Class A, Class B, Class C, etc) o Optics: in addition to the substrate material, this information allows the modeler to use the more accurate detailed cost generator Surface finish Edge thickness Center thickness Raw volume (billet size before machining) and Finished Volume Material density % light-weighting (indicate whether this applies to material removed or remaining) o Microwave components: even though these may be printed circuit board (PCB) mounted components, microwave elements need to be called out separately to indicate their high voltage requirements, RF frequency and part mass Additional information may be required to model MMIC and MIMIC components o Harness: higher cost accuracy can be achieved if each individual harness between assemblies is identified.

Typically, the instrument-to-spacecraft harness is assumed to end at a near-by connector bulkhead o Mechanisms: higher cost accuracy can be achieved if the custom mechanism design is broken down into these parts:

Mechanical parts: shaft, gears, bearings etc Electrical parts: actuator, launch lock, harness Opto-mechanical parts: encoder, position sensors o Detectors: detectors are typically modeled with a different parametric tool, SEER-H (for Hardware) where the following information is required Detector technology (e.g. HgCdTe, Silicon CCD, micro-bolometer) Wavelength of operation Array size (row pixels x column pixels) Frame rate (frames/sec) Readout noise (electronics/root Hz) Radiation tolerance (Rad) Units to purchase: flight, flight spares, and engineering grade test units Identify if flight spare detector(s) are assumed to be integrated with the other MEL components shown in that sub-assembly Program schedule: start date for development and start date for production

Vendor & Part #

• Specify if this is procurement of catalog or quoted item.

Volume

• Provide if relevant.

Quote Information

• Provide a pointer to where the quote has been provided in the proposal.

• Note the year of the quote so that inflation can be added, if necessary.

• Indicate the number of units to be delivered for that price, as it may include a flight spare and a development unit.

• Confirm that the price includes qualification of that hardware, including radiation testing, if applicable, otherwise a grassroots estimate of qualification expenses will need to be added.

• In order to accurately estimate the I&T associated with a purchased component, list the physical composition of that part: %electrical, %mechanical, thermal%, etc.

• FYI – Please know that for purchased items, there will be additional costs incurred for the purchase acquisition and the technical design and integration in order to capture all lifecycle costs associated with that purchase:

o The acquisition fee captures the largely non-technical labor to execute the procurement process.

o The design & integration fee captures the technical design, analysis, and test on the part of the instrument team to provide the engineering assessment that the specific COTS hardware meets all of the performance requirements for that instrument build, in that relevant flight environment, as well as to design the specific interfaces across multiple disciplines to accommodate that specific COTS part.

o In some cases, the cost estimate is lower using the modeled cost than a quoted cost due to these factors. Explore both alternatives.

Identical Items

• If this item is identical to another row, you can note it here (for NRE savings).

ETU Approach

• If you have an ETU and feel that is needs more explanation than just including it in the total of Flight Spare or Flight Unit, use this column to explain your approach.

Notes

• Any other relevant information…

• If you need additional columns, place them to the right of “Additional Information” column, and make the heading a different color.

• Feel free to add additional tabs and include all of the information you collected.

Flight Software

• There is a separate Excel file template for flight software CSCI specifications related to AO requirements.

Heritage Columns

This portion was added to meet AO requirements for number of pages to describe Heritage. These columns will be generated as proposal tables to summarize the mission or instrument’s Heritage claims.

Color-coding should happen automatically. The tables will be included in the Heritage Appendix of the proposal.

AO Requirements Discuss each element of any heritage from which the proposed investigation derives substantial benefit, including heritage from spacecraft subsystems, instruments, ground systems, flight and ground software, test set ups, simulations, analyses, etc. This discussion shall be at an appropriate level of granularity (e.g., component, assembly, subsystem) to clearly separate the heritage element from other elements of the design. The discussion of each element shall include:

• a concise description of the design heritage claimed;

• the anticipated benefits to the proposed investigation;

• a brief rationale supporting the claim that the benefits of heritage will be achieved; and

• for any proposed elements with substantial design heritage, a comparison of the cost of the heritage items to the proposed cost.

Proposals must substantiate all heritage claims, including descriptions of changes required to accommodate project-unique applications and needs. Where enhancements to heritage elements are proposed or heritage is from a different application, sufficient descriptions must be provided to independently assess the current level of maturity.

If a proposal claims any heritage from which the proposed investigation derives substantial benefit, this appendix shall discuss each element to an appropriate level of granularity (e.g., component, assembly, subsystem) to clearly separate the heritage element from other elements of the design. The evaluation team will use a scale with three levels (full, partial, or none) as illustrated in the table below.

Heritage Columns

All of these columns should be completed for internal use and cost assessment. The project will subsequently determine the best approach to present the data in the proposal, to make the strongest story for selection.

TRL (used for MEL & Heritage)

• State the TRL level at the time of proposal submission. Possible values are integers 1 through 9.

• Use NPR 7123.1C (Appendix E) TRL definitions, found on the “TRL Definitions” tab of the template.

• For additional assistance in determining TRL, refer to SP-20205003605, [NASA] Technology

Readiness Assessment Best Practices Guide.

Similarity to Existing

• Options:

o NT: New Technology, never flown before.

o EC: Engineering Change. Not New Technology; proven technology with minor modification in engineering approach/design, workmanship, manufacturing processes, size, or configuration which does not materially affect the performance limits of the technology, and does not change the performance of this element in its relevant environment.

o Identical: This element has flown before, and full heritage is leveraged.

Heritage Summary

• 7 Columns: adhere to the directions in the AO table above

• Options are F (Full), P (Partial), N (None), or NA (Not Applicable)

Reference Mission(s)

• List the acronyms of the mission(s) that have flown this element.

Heritage Justification and Additional Information

• Justify the TRL assessment and explain any nuances.

• List specific flight missions that flew this hardware (the more the better), and detail commonality.

What is the same, and what is different from the version flown? Is this a risk? Why or why not?

What testing do you plan to do to eliminate the risk?

• Use the words “identical” and “build-to-print” if accurate – these make a strong case. Note that there is no such thing as slightly modified build-to-print. But you can say that this component is identical except for X.

• Note if this is commercial off-the-shelf (COTS).

• Explain plans for environmental testing that will raise the TRL or validate this element in a new environment.

• If this is just an Engineering Change, explain why (eg. new layout but no new materials or functionality; or new shape is required to fit volume constraints).

• If the environmental difference does not impact this type of element, state that.

• Include analogous Cost Basis data here, if appropriate (or in the cost section).

Possible Additional Columns

Vendor Maturity Description

• Some Vendors provide a maturity code. If needed, please add a column. There may be slight variations in descriptions provided by the vendor, so this must be handled on a case-by-case basis.

An example translation from typical codes to TRL levels is:

Code Description TRL OTS Off-the-shelf (exists, sitting on the shelf), spaceflight proven

COTS Commercial-of-the-shelf (published price, I can buy it from a catalog), spaceflight proven

BTP Build-to-print 9 HSM Heritage Simple Modification, Minor Modification of existing design

HM Heritage Modification, Average Modification of existing design

HMM Heritage Major Modification, Major Modification of existing design

New New Design 5

Heritage Against Environmental Requirements Some missions may require definition of multiple “relevant environments” to assess TRL. If the mission design/architecture is more complex than a spacecraft bus with instruments, it may be necessary to define various “environments” which relate to TRL assessment of components being proven in the “relevant” environment. If necessary, these columns could be added:

Location

• Specify the (environment-relevant) location of this element in flight. For example, spacecraft interior/exterior, within a vault, etc.

Temperature

• The column header should state the possible temperature range for each location on this mission.

• Each row should state the temperature range within which this element has been qualified either through prior flight (specify) or through environmental testing.

Pressure

• The column header should state the possible pressure range for each location on this mission.

• Each row should state the pressure range within which this element has been qualified either through prior flight (specify) or through environmental testing.

Load

• The column header should state the maximum load expected for mission.

• Each row should state the maximum load for which this element has been qualified either through prior flight (specify) or through environmental testing.

Radiation TID

• The column header should state the maximum radiation dosage (TID) for each location on this mission.

• Each row should state the maximum radiation dosage for which this element has been qualified either through prior flight (specify) or through environmental testing.

PRICE Cost Modeling Columns

These columns have been added for the cost analyst to add the codes used for GSFC’s independent Cost Modeling. In light of the fact that a Cost Appendix is not permitted in Step 1 and Single Step proposals, a project may choose to include this information in the Heritage Foldout rendering of the spreadsheet.