1. HERITAGE,
A LOVE-HATE RELATIONSHIP
Wayne Hartford
Jet Propulsion Laboratory
California Institute of Technology
Copyright 2009 California Institute of Technology. Government sponsorship acknowledged.
Used with Permission
2. OUTLINE
• Introduction and Objective
• Laying the Foundation
• Execution
• Change Containment
• Plan B
• Additional Thoughts
• Summary
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3. INTRODUCTION
• Nowadays resource constraints and expectations drive us to incorporate heritage designs,
hardware or software into new product concepts and developments.
– In fact, concepts that fail to include some amount of heritage can be perceived as risky or wasteful.
• The promise of heritage, or a least the perception, is that it will provide:
– the best value for the customer
– the best performance
– a competitive edge
– reduced cycle time and cost
– reduced risk
Programmatically, you just have to love anything with that kind of potential.
• But if not managed properly the dream can become a nightmare. So the objective of this
presentation is to explain when and why things go wrong and suggest a proactive approach to
maximizing the potential of heritage assets or deciding not to use it at all.
• Although infusing a heritage asset into a design can be made at almost anytime in a
development, this presentation considers the scenario where the decision is made during
mission or instrument concept development.
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4. PERSONAL EXPERIENCE WITH HERITAGE
The Parents The Children
Widefield and Planetary Camera (WF/PC) .…..…. .....WF/PC II
Pressure Modulator Infrared Radiometer (PMIRR) …..….. …..PMIRR II
*Voyager ISS Wide Angle Camera………. …..Cassini ISS Wide Angle Camera
Mars Climate Sounder (MCS) …..….. …..Diviner Lunar Radiometer (DLRE)
*No personal experience on the Voyager mission
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5. WHAT IS HERITAGE
• The broad definition - something which is inherited from one's ancestors.
– For this presentation we’ll use a somewhat narrower definition.
“An existing asset that will be reused for the same or similar purpose for which it was originally
intended”.
• The asset in this case can be hardware, software, personnel or a design that successfully met its
original intent.
– Specific examples of personal experience with heritage include:
• Personnel.
• Hardware, ranging from components to subassemblies.
• Software code for ground support to flight operations and science data processing.
• Designs, ranging from components to entire science instruments.
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6. CAN WE BUILD IT, YES WE CAN
(THIS IS NOT AN INDICTMENT OF OUR ANCESTORS)
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7. LAYING THE FOUNDATION (PART 1)
The Proposal - where reasonable people do unreasonable things.
• The Objective
– The goal when developing and proposing a concept is to present the most
compelling plan to advance, e.g., science, technology, profits…
• The Attitude
– For the teams of people that successfully develop and propose concepts, optimism
is the most prevalent attitude and is crucial to the process.
• Because without a “can do” attitude you probably won’t.
• The State
– The team normally has more questions than answers and reality only exists at the
surface, so the natural state or condition that prevails is one of ignorance.
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8. LAYING THE FOUNDATION (PART 2)
• The Environment
– Concepts and proposals are developed in a world where most anything
is possible in spite of limited resources.
– And when complete they generally exist in the form of “cartoons”,
block diagrams and descriptions of how things will work or act.
– Yet, it’s into this virtual and fuzzy reality the team is compelled to
incorporate a heritage (real) asset.
– The logic or illogic of the decision to use a particular heritage asset is
accepted because typically no one knows enough to say that it won’t
work and besides, it’s expected.
– So in spite of the fact that the combination of attitudes and conditions
don’t lend themselves to correctly assimilating the heritage asset, it
becomes part of the baseline plan and worthy of highlighting.
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10. FETTERED OPTIMISM
• When can-do becomes must-do
– “The best day of my life was when we submitted our
proposal, the second best day was when we were
selected”
• Executing a plan is always more challenging than
creating one because reality begins to obsolesce our
plans from the moment we implement them.
• But realizing that the decision to use a heritage asset is
part of a plan that was created by “unfettered optimism”
is useful information and should cause you enough
concern to question the plan.
• Top this off with a potential loss of corporate knowledge
between submission and selection and you just might
have a bona fide challenge on your hands.
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11. GETTING STARTED
• The proposal that is to be implemented may be the most realistic and
sensible plan ever, in which case you only need to confirm the facts.
• It’s also possible that the plan is not the best thing since sliced bread.
• You might be inheriting the design for one component or the actual
hardware and software for an entire instrument.
• No matter what the conditions, there are some sensible steps that you
should take, if for no other reason but self-preservation.
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12. FIRST THINGS FIRST
• Performing Reconnaissance
– You’ll want to collect every scrap of documentation concerning the heritage asset you
can get your hands on.
• Requirement documents, ICD’s, review packages, board reports, action items, test reports,
analyses, waivers, inspection reports, failure reports, EIDP’s, etc.
• Then you should question everyone that originally worked on the heritage asset and request any
relevant notes, email or recollections they may have pertaining to the heritage asset.
– Keep in mind that each bit of relevant information that is missing probably means a
lesson that you’ll have to learn the hard way.
• If there is a significant lack of documentation, you should have your first concern.
– The information should be organized and then disseminated to the implementing team
for review and comment.
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13. DETERMINING THE VIRTUES
• There are three chief characteristics of a heritage asset that need to be understood.
They are:
– Reproducibility – is it practical to reproduce the heritage asset.
– Compatibility – how compatible is it with the new use.
– Adaptability – does the asset lend itself to modification.
• The degree to which these characteristics are true or present are a major factor in
how effectively and efficiently the heritage asset can be used.
• If the characteristics are complimentary then you have a fighting chance, but if
they’re contradictory then maybe the heritage asset isn’t the right solution.
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14. CAN WE BUILD IT, WE DON’T KNOW (PART 1)
• Reproducibility – “the ability to reproduce a asset within cost and schedule
constraints”.
– Unless the heritage asset is assembled, tested, has the right pedigree and sitting on a shelf ready for
use the first question that needs to be answered is whether it can be reproduced.
• Until you’ve confirmed that it’s practical to reproduce the heritage asset, understanding the other characteristics
have little value.
• And reproducibility may be the most difficult characteristic to understand because this is an all or nothing
proposition. Until know you that every part is available and every process can be duplicated, you’ve got
nothing.
• This also means that it can take a good deal of time to confirm reproducibility, so this effort should started
immediately.
– And just because a copy of the asset is sitting on a shelf ready to go doesn’t mean you’re out of the
woods.
• If the unit that’s sitting on the shelf is the last of its kind what will you do if it gets damaged. If you don’t have
sufficient spares to cover your needs and the unexpected then you have a different kind of risk.
• Or perhaps the unit doesn’t have the documentation necessary to establish its pedigree and deem it acceptable
for use.
– So even with the asset in hand determining reproducibility may still important.
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15. CAN WE BUILD IT, WE DON’T KNOW (PART 2)
• Availability, or lack thereof is what will jeopardize reproducibility.
– Availability of most everything, including:
• Electronics parts – especially old ones or custom parts like IC’s, hybrids and ASIC’s, for smaller
projects it’s usually not practical to fund the restart of a fab line or wait a year for a special part.
• Personnel – in-house or out, without heritage staff you loose access to undocumented
information covering things like design changes, assembly tricks, test configurations, etc.
• Materials – especially true for polymerics and solvents. Environmental concerns may have
affected the availability of certain chemicals or the ability to work with hazardous materials.
• Documentation – there’s the obvious things like a complete review package, a full set of
drawings or a comprehensive test report, and then there’s the things that are missing, and you
don’t know they’re missing.
• Capabilities – any loss of capability necessary for reproduction can compromise your plans and
this can be a real problem if it involves the loss of a proprietary design or processes performed
by a vendor.
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16. WILL IT WORK, WE HOPE SO!
• Compatibility
– From NASA’s Lesson Learned:
“Reliance on heritage hardware/software in spacecraft design, without a thorough analysis of compatibility
with mission requirements and required changes, can result in the use of design and components which are
inappropriate for the mission.”1
– There are any number of factors that can cause varying degrees of incompatibility.
– But it boils down to establishing the new and understanding the old.
• Establishing the new takes a good deal of time because it isn’t complete until a comprehensive
and stable set of requirements have been established and flowed down to the heritage asset.
• But you can begin to complete half the picture immediately, performing the reconnaissance will
help you to understand the limitations, problems and idiosyncrasies that could compromise
compatibility.
• As the other half of the picture unfolds you will gain a sense of whether the plan will hold
together or the heritage asset will have to be modified or replaced entirely.
• And it’s best not to assume that requirements or qualification testing previously performed on
the heritage asset have defined the actual design limits, often designs have more margin than
required. If there is any concerns regarding environmental compatibility, investigate and
establish the real limits of the design through reanalysis or test.
1 Lesson Number: 0346, Lesson Date: 1994-10-21
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17. CAN WE FIX IT, WE THINK SO!
• Adaptability
– From NASA’s Lesson Learned
“Often the more effort and expense that went into a device the harder it will be to change.”1
– Some things lend themselves to change and others don’t, the harder it is to make a
change the harder you should fight the change.
– And a lot will depend on the type of change you need to make, but some
characteristics of the heritage asset should cause concern if modification is a
consideration.
– Is it the last of its kind and can’t be reproduced?
– Do you lack understanding of the asset?
– Is it complex?
– Is the packaging dense?
– Are there hazardous materials involved?
– Is it delicate?
– Is it bolted together or glued?
1 Lesson Number: 0346, Lesson Date: 1994-10-21
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18. CHANGE CONTAINMENT
• Changing an existing design or hardware is not like the changes that take place as a new design
evolves.
• It’s an intrusion into something that has already been optimized for a very specific purpose and
it’s unlikely that adaptability was built in.
• So before you think change, remember the three rules of using heritage,
1. It’s best to leave the heritage as is.
2. You really don’t want to change a thing.
3. Don’t even think about it.
• But in spite of the rules you may well find yourself in the unenviable position of changing the
heritage asset, in which case you should think of the change as a “fault” which needs to be
contained.
– As resistant as you should be to any change, be even more resistant to changes that have the potential
to propagate.
– Keep in mind that changes to the design or actual hardware may force requalification testing.
– Stay open to the possibility of changing your mind, and deciding after all not to modify the heritage
asset.
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19. PLAN B
• Diminishing Returns
– Remember the reason the heritage asset was there in the first place, it was suppose to
provide better value, reduce cycle time, cost, risk, etc.
• But there’s another risk, one of sticking with the original plan no matter what. And then slowly
but surely it becomes more and more difficult to force the heritage asset into the new design until
the size of your investment prevents you from changing course.
• If You Have No Where Else to Turn You Probably Won’t Turn.
– So if there are any concerns regarding reproducibility or compatibility and adaptability
and it looks like the promise might be broken, you owe it to your customer and yourself to
have a Plan B.
– Without too much expense a fallback plan can be carried through PDR and if by that time
it’s still not clear that the heritage asset will work, then it’s even better that you have an
option.
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20. BEING PROACTIVE
• Proposing
– Spend some quality time validating the decision to use the heritage asset.
– Manage expectations by improving communications between the proposal team and the
implementation team.
• Execution
– Don’t trust the plan.
– Start the reconnaissance early.
– Dig deep in the details when determining reproducibility.
– Strive to establish compatibility as early as possible.
– Investigate the real capabilities of the heritage asset.
– If compatibility is a problem then consider creating a more suitable environment as opposed to
modifying the asset.
– Contain changes to prevent the waterfall effect.
– Give yourself a way out, create a Plan B
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21. ADDITIONAL THOUGHTS
• Spare hardware is generally second class.
• AT TRL 5 the readiness of a component has made the leap to operation in a “relevant
environment”. If the anticipated environment lies outside the bounds of the heritage
environment for any component or component within an assembly then consider the design to
be at TRL 4 and manage it accordingly.
• Engineers generally don’t care to design a peg to fit someone else’s hole, they prefer to design
both the peg and the hole.
• Heritage in staff is highly desirable, find out who worked on the previous development and
secure their support for the new build.
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22. SUMMARY
Heritage is a double edged sword, it can be seen as a way to offset the cost
and risk of implementing new technology somewhere else in the project.
But it can in fact preempt an innovation that would have otherwise been
created.
It’s seldom all that its cracked up to be but it does have a place and can
provide a benefit if used sensibly and managed properly.
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