Background
Chris Chromik, a long-time PRICE user and member of the IPAO at Langley
Research Center provided independent cost estimates to Jet Propulsion Laboratory
on the Space Interferometry Mission (SIM) project from Oct. 2000 through
April 2001. Chris attributed his successful application of a parametric
model to the totally new interferometry technology to the flexibility of
the PRICE Hardware Estimating Model and the PRICE Software Estimating Model
to model low level components.
Estimating at a lower level made the process more practical because at the subsystem level there are no technical or cost analogies. Open communication with engineers and analysts at Jet Propulsion Laboratory, TRW, and Lockheed Martin also contributed to the estimate's completion, and Chris considers this to be a key factor in successfully applying parametric models to the space environment.
The Approach for Modeling Interferometry
Chris approached this new technology by breaking down the subsystems (starlight,
metrology, real-time control, precision support structure) into the components
(~300 total "boxes"). While many of these components pushed the state of
the art in functionality, they were items for which a range of complexity
factors already existed in PRICE H (optics, electronics, structure). Chris
went through every item with the project to find out the state of the design
and engineering complexity.
Calibration
Chris calibrated at the "box level" wherever possible. This typically was
done for common spacecraft components such as antennae, transponders, and
where historical vendor prices were available. The spacecraft bus was about
80% calibrated. For the items that could not be calibrated such as the unique
instrument components, Chris used the conceptual complexity generator in
PRICE H. This is a tool the PRICE clients and consultants often use to determine
complexity factors for uncalibrated items. The conceptual generators provide
modeling guidelines based on functional descriptions, material type, number
of parts, electronic component type. Also, Chris used the conceptual generator
to crosscheck some of his calibrated complexity factors.
Schedule
The nominal schedule calculations in both PRICE H and S were used to verify
the program management's schedule for SIM. Model output durations were exported
to Microsoft Project and compared to the project schedule.
Challenges
Chris' greatest challenge was determining the appropriate integration levels
in PRICE H and whether the highest integration input parameters would actually
capture the difficulty. There were many redundant pieces of hardware in
each subsystem, so some economies of scale had to be captured as well as
integration costs for redundant hardware interfacing with multiple subsystems.
Chris also had to model the subcontractor tiering levels which were complicated
due to the organization of the integrated product development team. Modeling
the various mark-up costs for each vendor at the appropriate level was a
concern (estimating the multiple G&A fees if LM buying from vendor, for
example). For all of these challenges, Chris was able to crosscheck his
approaches with a PRICE Executive Consultant.
Keys to Success
According to Chris, PRICE can be applied to estimating new, space technology
because it is flexible enough to estimate at low levels of detail that can
often break complex subsystems into manageable components. Communication
with the project team to model the development process, and with design
engineers to translate technical parameters into model inputs is also instrumental
in the successful application of PRICE.