Exploring the Unknown - NASA's History Office

the desired average expected return on investment was 20.8%, or a risk premium of about
11% over current operations. The 29.5% projected return on investment for silicon ribbon
manufacturing exceeds this criterion by a substantial margin.
Another more comprehensive method of risk analysis is to evaluate risk as a function
of time and then risk-adjust the cash flows for use in calculating a risk adjusted rate of
return. To do this, first the technical, legal, and market risks associated with the commercial
space manufacturing of silicon ribbon are evaluated.
Evaluation of technical risk required definition of the research and development
activities for the silicon ribbon process and process apparatus. The research and development
required was divided into three phases, ground and sounding rocket research and
development, Shuttle sortie development, and pilot plant demonstration. A proposed
timetable for these activities is shown in Figure 18. The approximate cost of these activities
is $36M, not including launch costs. For the purpose of risk analysis, three objectives
were identified as being necessary to the technical implementation of space manufacturing;
basic process development, manufacturing plant development, and mission operations.
These objectives were divided into thirty-six technical risk elements in three levels
of detail similar to a work breakdown structure. These elements were then classified as
(1) proven space technology, (2) existing knowledge requiring development for space
application, and (3) new technology requiring research. The applicable range of probability
of success for these categories is: (1) greater than 0.99, (2) more than 0.95 but less
than 0.99, and (3) less than 0.95, respectively. A subjective evaluation was made of where
the risk for each element fell within the applicable range. The results of this analysis are
shown in Figure 19. The probability of technical success increases with time from 0.22
today, to 0.48 at the completion of ground and sounding rocket research and development
in 1981, to 0.69 at the completion of Shuttle sortie process demonstration, and finally
to 0.95 at the completion of a pilot plant demonstration in 1985.
Figure 18. Research and development schedule
EXPLORING THE UNKNOWN 511
Microgravity Flights
Ground Experiments
Physical Properties
Meniscus Shaping
Process Apparatus Development
Sounding Rocket
Physical Properties
Melt Stability and Liquid/Solid Interface
Melt-Seed Interaction
Crystal Growth in Microgravity
Crystal Morphology
Meniscus Shaping in Microgravity
Shuttle Sorties
Meniscus Shaping
Melt/Feed Rod Interaction
Continuous Crystal Growth
Reseed Effects
Thermal and Mechanical Control
Solar Furnace
Prototype Process Operation
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