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APPENDIX
Compilation of Study Findings'
Conclusions, and Recommendations
Following is a compilation of the study findings, conclusions, and
recommendations.
FINDINGS
The committee arrived at the following findings:
Pending 1 (Chapter 2~: Of the three significantly different SDI
modes of operation (housekeeping, alert, and burst mode), require-
ments for the alert mode are inadequately defined, yet they appear to
be a major design-deterrn~nant. For that mode, the unprecedented
high power levels, durations, and unusual time-profiles-as well as
the associated voltages and currents-which are envisioned will usu-
ally make extrapolation from previous experience quite risky and
unreliable. A possible exception is in the area of turbine technol-
ogy, where an adequate range of power leveb has been validated for
terrestrial applications, although not for flight conditions. Proposed
space power systems will need to be space qualified for long-term
unattended use.
Finding 2 (Chapter 4~: The space power subsystems required to
power each SDI spacecraft are a significant part of a larger, complex
system into which they must be integrated, hence for obtaining a
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APPENDIX E
valid analysis they cannot be treated completely separately. (See
Conclusion 2 and Recommendation 1.)
Finding 3 (Chapter 4~: Existing space power architecture sys-
tem studies do not adequately address questions of survivability,
reliability, maintainability, and operational readiness that is, avail-
ability on very short notice.
F~ndmg 4 (Chapter 4~: Existing SDI space power architecture
system studies do not provide an adequate basis for evaluating or
comparing cost or cost-e~ectiveness among the space power systems
examined.
Finding 5 (Chapter 2~: Among the power systems that are
candidates for SD! applications, the least massive, autonomous self-
contained space power systems currently being considered entail tol-
erance of substantial amounts of effluent during system operation.
The feasibility of satisfactorily operating spacecraft sensors, weapons,
and power systems in the presence of effluent is still unresolved.
Finding 6 (Chapter 3~: Beaming power upward from earth by
microwaves or lasers (see Recommendation 6) has not been exten-
sively explored as a power or propulsion option.
Finding 7 (Chapter 6~: The present overall rate of progress
in improving the capability of space power-conversion and power-
conditioning components appears inadequate to meet SD] schedules
or NASA needs beyond the Space Station.
Finding 8 (Chapter 3~: The time needed for the development
and demonstration of a U.S. space nuclear reactor power system
currently exceeds the time required to plan and deploy a mission
dependent upon that power source.
CONCLUSIONS
The committee reached the following conclusions:
Conclusion 1 (Chapter 2~: Multimegawatt space power sources
(at levels of tens to hundreds of megawatts and beyond) will be
a necessity if the SD] program is to deploy electrically energized
weapons systems for ballistic missile defense.
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APPENDIX E
131
Conclusion 2 (Chapter 43: Gross estimated masses of SDI space
power systems analyzed in existing studies appear unacceptably large
to operate major space-based weapons. At these projected masses,
the feasibility of space power systems needed for high-power SDI con-
cepts appears impractical from both cost and launch considerations.
Avenues available to reduce power system costs and launch weights
include (a) to substantially reduce SDI power requirements; (b) to
significantly advance space power technology.
Conclusion 3 (Chapter 3~: The amount of effluent tolerable is a
critical discriminator in the ultimate selection of an SDI space power
system. Pending resolution of effluent tolerability, open-cycle power
systems appear to be the most mass-effective solution to burst-mode
electrical power needs in the multimegawatt regime. If an open-cycle
system cannot be developed, or if its interactions with the spacecraft,
weapons, and sensors prove unacceptable, the entire SDI concept will
be severely penalized from the standpoints of cost and launch weight
(absent one of the avenues stated in Conclusion 2, Chapter 4~.
Conclusion 4 (Chapter 2~: The rate of rme ("ramp-rate" ~ from
zero to full burst-mode power level appears to be a critical require-
ment. It is not apparent to the committee what relationships exist
among elapsed time for power build-up and system complexity, mass,
cost, and reliability.
Conclusion 5 (Chapter 5~: Major advances in materials, com-
ponents, and power system technology will be determining factors in
making SDI space power systems viable. Achieving such advances
will require skills, time, money, and significant technological innova-
tion. The development of adequate power supplies may well pace the
entire SDI program.
Conclusion 6 (Chapter 6~: Refocusing SDIO resources toward
near-term demonstrations could delay development of advanced po-
wer technology, and thereby seriously jeopardize meeting long-term
space power program objectives.
Conclusion 7 (Chapter 3~: A space nuclear reactor power sys-
tem, once available, could serve a number of applications- for ex-
ample, in NASA and military missions requiring up to 100 kWe of
power or more in addition to SDI.
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APPENDIX E
Conclusion 8 (Chapter 2~: Survivability and vulnerability con-
cerns for SDI space power systems have not yet been adequately
addressed in presently available studies relevant to SD} space power
needs.
RECOMMENDATIONS
The committee arrived at the following recommendations:
Recommendation 1 (Chapter 4~: Usmg the latest available ~nfor-
mation, an in-depth fuB-vehicle-eystem preliminary design study-for
two substantially different candidate power systems for a common
weapon platform-sho~d be perfonned now, m order to reveal sec-
ondary or tertiary requirements and limitations in the technology
base which are not readily apparent in the current space power ar-
chitecture system studies. Care should be exercised in establishing
viable technical assumptions and performance requirements, includ-
ing survivability, maintainability, availability, ramp-rate, voltage,
current, torque, effluents, and so on. This study should carefully
define the available technologies, their deficiencies, and high-leverage
areas where investment will produce significant improvement. The
requirement for both alert-mode and burst-mode power and energy
must be better defined. Such an in-depth system study will improve
the basis for power system selection, and could also be helpful in
refining mission requirements.
Recommendation 2 (Chapter 3~: To remove a major obstacle to
achieving SD] burst-mode objectives, estimate as soon as practicable
the tolerable on-orbit concentrations of effluents. These estimates
should be based to the maximum extent possible~n the results of
space experiments, and should take into account unpacts of effluents
on high-voltage insulation, space-platform sensors and weapons, the
orbital environment, and power generation and distribution.
Recommendation 3: Rearrange space power R&D priorities as
follows:
a. (Chapter 3) Give early, careful consideration to the regu-
latory, safety, and National lDn~rironmental Policy Act re-
qu~rements for Mace nuclear power systems Tom manufac-
ture throw launch, orbital service, safe orbit requirements,
and disposition.
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APPENDIX E
133
b. (Chapter 6) The SP-100 nuclear power system is applicable
both to SD] requirements and to other civil and military
space missions. Therefore SP-100 development should be
completed, following critical reviews of SP-100 performance
goals, design, and design margins.
c. (Chapter 6) SOT burst-mode requirements exceed by one
or more orders of magnitude the maximum power output
of the SP-100. Therefore both the nuclear and nonnuclear
SD! mult~megawatt programs should be pursued. Hard-
ware development should be coordinated with the results of
implementing Recommendation 5.
Recommendation 4 (Chapter 6~: Consider deploying the SP-
100 or a chemical power system on an nn~nned orbital platfonn at
an early date. Such an orbital "wall sockets could power a number of
scientific and engineering experiments. It would concurrently provide
experience relevant to practical operation of a space power system
similar to systems that might be required by the SDI alert and burst
modes.
Recommendation 5 (Chapter 5~: Make additional and effec-
tive m~restments now in technology and demonstrations leading to
advanced components, inclu~mg but not limited to:
thermal management, including radiators;
. materials structural, thermal, environmental, and super-
conductmg;
electrical generation, conditioning, switching, transmission,
and storage; and
. long-term cryostorage of H2 and O2.
Advances in these areas will reduce power system mass and environ-
mental impacts, improve system reliability, and, in the long term,
reduce life-cycle power system cost.
Recommendation 6 (Chapter 3~: Review again the potential for
ground-based power generation (or energy storage) with subsequent
electromagnetic transmission to orbit.
Recommendation 7 (Chapter 2~: After adequate evaluation of
potential threats, *farther analyze the subject of ndnerabdity and
survivability, mainly at the overall system level. Data resulting
from implementing Recommendation 1 would be appropriate for this
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APPENDIX E
analysis. Pending such analysis, candidate power systems should
be screened for their potential to satisfy interim SDIO survivabil-
ity requirements, reserving judgment as to when or whether those
requirements should constrain technology development. Convey the
screening results to the advocates of those candidate power systems,
to stimulate their finding ways to enhance survivability an they de-
velop the technology.
Recommendation 8 (Chapter 6~: ICb further U.S. capabilities
ant! progress In civil as well as military applications of power tech-
nology, both on the ground and in space, and to maintain a rate
of progress In advanced technologies adequate to satisfy national
needs for space power, plan and implement a focused federal pro-
gram to develop the requisite space power te~mologies and systems.
This program-based on a umItlyear federal commitment~hould be
at least as large as the present combined NASA, DOD (including
SDIO), and DOE: space power programs, Independent of the extent
to which SD! itself is funded.
Representative terms from entire chapter:
sdi space
