299
EXTRATERRESTRIAL
APPLICATIONS
OF
SOLAR OPTICS
FOR INTERIOR
RI,UMINATION
N93-17449
David
A. Eijadi
and
Kyle
D. Williams
BRW, Inc.
700 Third Street South
Minneapolis
MN 55415
Solar optics is a terrestrial technology that has potential extraterrestrial applications. Active solar optics
(ASO) and passive solar optics (PSO) are tuo approaches to the transmission
of sunh'ght to rerru)te
interks_ spaces. Active solar optics is most approptgate for task illumination,
while PSO is most
appropriate for general illuminations. Research into solar optics, motit_ted
by _
conse_c_tion, has
produced lightu_ight
and low-cost materials, products
that bale applications to NASA's Controlled
Ecological Life Support System (CELSS) program and its lunar base studies. Specifically, pr_m h'ght guides
have great potential in these contexts. Several applications of solar optics to lunar base concepts are
illustrated.
INTRODUCTION
The purpose
of solar
of the visible
or
task
optic
systems
and
powered
require
effectively
(ASO)
A sustained
thereby
precision
diffused
need smaller
aarpdwer source.
system
collecting
solar
design
and
effectively
require
initially
remote
to develop
the
developed
interiors
research
beamed
• .
criteria
design
the
need
beamed
will
Active
light
only
systems
and
beamed
and
The
sunlight
impetus
quantity
basic
sizing
lighting
and
and directionality
types
of
PSO
low-cost
S}_tem
materials
those
(CELSS)
of
strategies
(E/jad,)
of the available
that reduces
in comparison
an aperture
1983).
based
on
to con-
The
system
the
desired
sunlighL
There
systems
(Fig.
1)
[. t
_-
refractive
are two
have
throughout
included
possible,
focal
areas
the development
paid to alternatives
with
INTERIOR LENS
_N_
program
energy
the
and
development
conservation,
nonimaging
within
the
use
for heliostat
controls,
control
lessons
learned
transferable.
\
\
..j_L_....7
.
\
_,r]
-.
[
enclosures.
particular
attention
systems,
and strategies
artificial
that
reduce
the volume
of optical
material
required
to transtx)rt
light.
Terrestrial
and extraterrestrial
criteria will no doubt be different;
are directly
"%-.
II
of
hazards,
ease
for selective
optics
protective
of ASO systems,
integrated
of the
"X_\
II
II
II
considerations
of
"-_'///"_
_
][
of
or
applications
control
area
\/N.
that
When
imaging
optics are used, the possibility
is eliminated
through
the use of selective
filters
many
of fenestration
systems:
_
NASA's
PSO designs.
conflagration
however,
OPTICS
to lighted
designing
I f
in
.sources
enables
size
and
are used
light
natural
into
Wherever
has been
ventional
EXTERIOR LENS
for this
conservation,
parallel
Life Support
.
transmissivity.
Throughout
is a form
of aperture
MULTIPLIER LENS
technologies
_.
that do not produce
life or safety
weatherability,
and optical coatings
containment
PSO system
the ratio
o,ar
opt,c
,ec o,o es
for energy
requirements)
PSO and ASO systems
of lens designs
of construction,
and
light.
control
buildings.
(lightweight
volumeric
Controlled
Ecological
lunar base appli_:ations.
Critical
build
sunlighting
for concentrating
of Earth-sheltered
and development,
appfied
minimize
(PSO)
The
SOLAR
\
effort
began
in,9 8
Uu.n
the
"ene,
were
on
optics
as beamed
deliver
but
use
of general
dependence
Passive
as well
areas
is to enable
as a source
reduce
to
light
systems
design
.spectrum
illumination.
less
deliver
optics
(SO)
of the solar
illumination
electrically
solar
portion
PASSIVE
in developing
DETAIL OF "MULTIPLIER LENS"
terrestrial
Fig. 1.
Refractive PSO system
and
300
2nd
Conference
on Lunar
Bases
and Space Aclivities
Fresnel
lenses
of the
COLLECTOR
collector
in
a uniform
array
system
is turned
is diffused
of
efficiency,
light
the
and
a mathematical
efficiency
(E_ad,;
diffusion,
and
The
absorption
at
ratio
model
1983).
the
were
the
acrylic
Passive
solar
optics
require
system.
determination
and the distance
is
aimed
of the
is a function
at
of repose
of the latitude
from the system
a low
the
For
overall
scattering,
to
through
for each
system
the
the arrays.
electrical
to the target.
horizon.
light
a separate
angles
An
reaching
contribute
backup
arrays
area.
to estimate
dirt,
as light is reflected
The
target
used
of
of illumination
the
cff the
resulting
of illumination
depreciation
systems
direction,
a horizontal
,surface, can be
design
purposes.
Empirical
effects
in
90 ° to that
in each
the target to the total available
on
assumed
to be 10% for preliminary
testing
},
light
distribution
approximate
'.._',,........--- REFLECTOR
reflector
array so that
lighting
section
of
is designed
The topmost
Earth-based
systems,
for
panel
each
successively
"abutting collector
panel is aimed higher until all the
useful or desired
annual solar horizons
are within
one or more
regions
of the array. The
to redirect
Active
in that
Fig. 2.
solar
they
systems
(Fig. 2).
Each
system
terrestrial applications;
however,
to extraterrestrial
applications.
undesired
radiation
components
selective
to
radiation
the heliostat
and
and
needs
similar
in terms
protecting
proposed
is worth
of
the
exterior
shield
with
interior
PASSIVE
PSO
system
Fresnel
multiplier
lens;
one focal
consists
of
three
lens;
and exterior
apart
generally
result
can
system
the multiplier,
lenses
in an axial
The
cone
of vision
approximately
refractive
mechanically
of an ASO system
transport
and
(4)a
(3)artificial
distribution
system
RADIATION
SOLAR
Z)STAT
of view
but
The
PSO
exhibits
at an angle
GUIDE
and
expense
12.5% and 6.25%,
system
be installed
length
REDIRECTING
MIRRORS
of 32 °. The
at the
of view on one or both
MIRRORS
are spaced
of
depend-
INTERMEDIATE
NETWORK
axes, respect-
some
chromatic
to the ground
PASSIVE
installations
elements:
(3)reflector
sunlight
reflector
of
the
SOLAR
reflective
( I ) collector
OPTIC
equal
PSO
array; (2)
system
array.
The
collector
array
the
clerestory
window
opposes
the collector
consist
clerestory
through
faces
the
to the
array and
DISTRIBUTION
SYSTEM
SYSTEM
of
window;
sun
and
reflector
redirects
the
to the desired
target area. Sunlight
is diffused
approx10 ° when reflected
from either array. The pattern
of the
Fig. 3.
are ( 1 ) the
networks;
of the site for best performance.
REFLECTIVE
array. The
cone
the cone
It should
to the latitude
sunlight
imately
the
efficiency,
aberrations.
reflects
PSO ,systems
that
(3)pris-
arrangement.
the limitations
in a .solid angle
double
ing on increasing
and
controls;
elements:
and
of focal
major
from
MIRROR
Without
Current
with
SYSTEM
major
Fresnei
interior
length
OPTIC
azimuth.
three
a heliostat,
components
000
lens in order to
axes altitude
and
ively.
The four
(2)intermediate
(Oleson
lens is placed
ahead of the exterior
the cone of vision in one or both
total
are distinguished
a
multiplier
increase
multiplier
OPTICS
for protecting
consideration
SOLAR
(2)exterior
lens. The
approximately
f-stop
heliostat;
sources
process
applies
of filtering
A meteorite
to that
systems
a component,
area.
1986).
A refractive
matic
physically
of the CELSS module
Olson,
is described
the same design
Consideration
addressed.
coating
REFRACTIVE
(1)
of
be
SOLAR
array are designed
to the target
tracks the solar disk. It is also possible
to physically
integrate
the
electrical
backup
illumination
system within the sunlight distribu-
Reflectb,,e PSO system.
tion network.
reflective
optics
have
of the reflector
the collector
ACTIVE
MINIMUM TARGET WIDTH
_TARGET
FLOOR
angles
the light from
Active solar optic system.
light
(Fig. 3).
Eijadi and
Simply
put,
reflectors
network.
tally
the
heliostat
or ve,*,ically
to
occupied
space.
Various materials
et al., 1987).
cables,
and
tracks
that beam the
The intermediate
the
delivery
were
prism
device,
a series
which
of
materials
included
holographic
pipes,
(PLG).
Distribution
guides
illuminates
for use in the system
network
pipes,
light
sun and positions
investigated
Intermediate
reflective
the
sunlight
into the intermediate
transport
network
transports
the light horizon-
is
evaluated
reflectors,
evaluated
specular
reflectors,
on the basis
of
interior
performance,
and
of integration
or
cost,
constructibility,
best
with
the
least
practices.
intermediate
amount
ease
networks
of physical
were
material
pipes
worked
nearly
as well.
with
the preferred
choice
for the
sources
should be high-intensity
as close
to the distribution
for that
resource
unnecessary
distribution
discharge
device
prior
to
absorption
and maintenance.
A proof-of-principle
model
at the
University
building.
of
Sunlight
alternately
and
introduced
distributions
with
was
light
into
nearly
Civil
from
identical
halide
fire
should
materials
used.
common
horizontal
practice.
Among
those
are heliostats,
distribution
networks,
and fixtures capable
electric
systems
for
have
light.
been
A conceptual
are
reduced
of
this paper
relates
transportation
The
light
to the
work
use
guides
on ASO
of both
are hollow
tubes
more
stable
resist
higher
made
at varying
weighs
formed
than
the
made
temperatures,
thicknesses
using the principle
The film used
thick
walls
polycarbonate,
248°F
but
about 0.13 lb/ft (0.064
into nearly microscopic
similar
study
plant
prompted
typically
the
presented
guides
either
for
the
light.
an optical
190°E
polycarbonate
Each
is 0.022"
film
(0.56
can
can
ram)
be
and
kg/m).
The surface of the film is
prismatic
facets that transmit
light
in the ASO system.
It is approximately
0.022"
(0.56 mm) and comes in widths up to 24" (61 cm). The
of the film are formed
into grooves
so that sunlight
is
reflected
with
backing
is added
a diffusion
to the film.
with
other
synthetic
any
OPTICS
of approximately
TO
FREEDOM
clearly
identified
solar
with
electric
other using
source.
fiber optic
Fresnel
power,
behavior
investigation
of fiber
cables
cables
hybrid
lenses
used
concentrates
during
the
light on 2712
The
fluorescent
10%. An aluminum
30
minutes
of
darkness
in the fluorescent
lamps
spaced
other
will have
because
transmit
each
a shorter
of mutual
by
system
light
of an HID
with
the
attributable
evaluated
HID/fiber
advantages
life span
in the
system.
optic
cables
light
source
and
HID/fiber
lamp
optic
were
than
HID
more difficult
lamps cannot
Each
study
of these
utilized
technology;
would,
optic
because
optic
(3)HID
in turn,
(1)the
cables
lamps
maintenance,
when
these
costs
work
require
the greatest
of additional
system
was
efficiency
and
and design
represented
HID
would
be transHID light source
that
fiber
system,
to the development
of better
and
The
hazard;
technology,
a_.d significant
losses of efficiency
at the interface
of the two; (2)higher
costs
an unknown
cooling,
system
is a health
interference.
considered
via fiber
and (4) this configuration
systems
The
orbit.
would
provide
lighting
would
optic
lamps
during
lamps
with the cables coming from the heliostat.
about the HID/fiber
optic system
include
integration
directly
HID light
manageable.
hybrid
be integrated
Concerns
associated
a
that transmit
lamp replacement
will be
HID lamp; and (4) fluorescent
was deemed
unknown
assumed
using
and the
is utilized
fluorescent
lights and fiber optic cables. Solar illumination
mitted
to the plants as before,
but a remote
would
one
glass fibers
adjacent
to the plant
trays,
to the plants
and the solar
( l ) mercury
closely
mass.
cycles
lamps
a remote
provide 7500 fc (80,700 lux).
Concerns
in using the fluorescent/fiber
the
and
systems,
with
to
grow
illumination
fluorescent
integrated
to
cost,
short
and
need
1986).
In fact,
based
on a
volume,
with
of two
optic
the
illumination
system using fluorescent
lamps was identified
as the
In this system,
a heliostat
with an array of 2712
fluorescent
lamps,
750fc
(8070 lux)
in
film. The films are called
3M. The acrylic film is
the
of
growth
lamps; (3)fluorescent
than with a remote
of total internal reflection
(Saxe et al., 1986).
in the PSO system
is an optical-grade
acrylic
to that used
outgassing
are
in the
and artificial
with
but
vs.
study
lighting
combination
concerns
light
of the
with
OF SOLAR
design
Unknown
be
sunlight
grade polycarbonate
or acrylic polymer
"Scotchlamp
Film" by their manufacturer,
than
degradation
to
USED
systems
of the prism
and distribution
greater
the
associated
light to the plant-growth
units. Solar illumination
the 60 minutes
of available
sunlight,
and the
selective
offered
PROPERTIES
OF MATERIALS
FOR SOLAR OPTICS
of the
no
artifidal
supplement
(2)
aspect
be
base,
Hazards
SPACE STATION
identified:
unique
or a lunar
in
vertical
and
of delivering
A variety
heliostats
system
is presently
marketplace.
The
station
APPLICATIONS
The hybrid
best choice.
were
identical
A complete
Canada.
of ASO
and/or
heliostat
source
by Whitehead
systems
to
with
Engineering
PLG and produced
in Toronto,
components
control
the
Mineral
operation
Several
and
space
not be a problem.
parametric
the energy
using
of
is feasible.
such as the
were
downward
associated
and
sunlight
of the
device
and
in
in LEO. No
a rethinking
distribution
fabricated,
coatings
with
The
designed,
beamed
conjunction
plants in the CELSS module
(Oleson
and Olson,
an all-solar
illumination
system
was preferred,
efficiencies.
installed
in
to any
a metal
the same
guides
because
constructed
Minnesota's
oxygen
be subjected
(light
fixture)
should
be linear
and oriented
maximize
distribution
and minimize
room losses
to the
com-
the films degrade
monatomic
not
as possible
utilization.
design,
exposed
personal
into
device. Artificial
light
(HID) sources located
is paid for and should
losses
light
with
301
decidedly
incorporated
Prism
the current
impact
needed
films should
their design. They should be dedicated,
airtight passageways
that
are as short as possible.
Depending
on precise distances,
PLG and
reflective
With
of or
similar films
(A. Zderad,
optics
manufacturing
process to determine
if direct exposure
If the films are used in a controlled
environment
included
fiber optic cables, diffusing
and PLG. Each
component
was
conventional
construction
It was concluded
that
1988).
presence
films
lens guides,
devices
the
of solar
testing has been performed
in deep ,space. A further investigation
of the thermal
and ionic space environment
in relation
to these
(E/jadi
fiber optic
solid-angle
Applications
Testing
has been performed
on
low-Earth-orbit
(lEO)
environment
munication,
the
Williams:
is an
were
were
are
required
preheating;
mass of all the
fiber optic cable required.
identified
as having
the
safety,
accessibility,
compared
to the
centralized
fluorescent
302
2nd
While
solar
Conference
two
artificial
transmission
guides
rather
than fiber
to improve
the
cost
and utilize
source.
The
are
technology,
so a reduction
transmit
to eliminate
cables
physical
PLG is a
(C. Wheelwright,
to utilize ASO
of HID lamps
and fiber
for
will
of light
reduce
with
less
optic
could
module;
concentrate
and (4) The
the
system
rays
station
space
air plenum,
fluorescent
mass for the
light
the opportunity
the
heliostat
to a porthole
incorporating
the
Domvtn,
exists
on
PLG can filter
UV and IR radiation
in a similar fashion as fiber
important
when plant growth is concerned
(Saxe
the
harmful
optics, which
et al., 1986).
down
is similar
is
OF SOLAR
TO THE
The
initial
advantage
conservation
SO on
of
of available
the
outposts
Moon
for
wavelengths,
interior
heliostat
thereby
ASO
for
scheme
First,
many
with
solar
The
disadvantages
and,
of using
second,
harmful
concepts
SO
from
the
may be mitigated
night
lunar
are,
loss
to be excessive
lunar
this
fact
we
operations.
energy
is desirable
made
the
wherever
first,
equatorial
plane
for continuous
latitudes, there
nights.
is only
In either
location,
axis enables
on tracking
the horizontal
day
than
rather
the
could
then pipe
illumination.
spectrum
for
simple:
The
need
for
housing
(H6rz,
to provide
in
general
and ASO is used to provide
with it.
an operational
1985).
applications
access
during
of solar
luminance
has not
been
that
base
from
Fig. 4.
the
This
office
buildings.
illumination
habitat
use
is located,
lighting.
Lun_ outpost using ASO.
of solar
either
as
at the lunar
of the Moon.
SOLAR
RADIATION
_....
•
PSO WITH
COATING
•"
SELECTIVE
\
__.A;O_
1V2° to the
availability
two-week
the design
from
of the
movement
there
systems.
emphasis
The
movement
be simplified
small
to be placed
of the sun during
seasonal
is a
(Burke,
1985). At
days and two-week
PSO and ASO systems
Earth-based
the PSO design
vertical,
ecliptic,
the
on
by tracking
lunar
the ,sun
and speculated
on
schematic
diagrams
illustrated
lunar
the
..
-
....
.-..
We have taken several lunar base schemes
how PSO and ASO might
be apl_iied. The
represent
,A. MoouEs_
Earth.
stages
of
development
..
. .
,
Fig. 5.
.
-.-.
.
.
. •
• . . .
.
Operational
/
....
..
.
.
-
.
base using ASO and PSO.
or
,scheme
determined.
the
light
As the base
solar
Iack
the
This concept
for the CELSS module.
in Fig. 5 shows
is used
is to integrate
the ASO ,system can grow
a lava tube
for
(Walter,
optics
proves
lunar
sunlight
will be
Similarly, the ASO design
can
on one axis rather than two.
here
concept
outpost
light diffuser.
Removing
the
could be lined with PLG. A
interior
terrestrial
optics
concepts
environradiation
if dust
assumption
inclined
will be modified
tilt of the lunar
One
an
evaluation
use of SO would be if a polar location were
site for hmar habitation.
Because the Moon's
possibility
the lower
on the Moon
Solar
visible
a primary
source
of power
and interior illumination
poles, or as a secondary
source at the lower latitudes
The most promising
selected as the initial
interesting
an HID lamp,
modules,
current
such
lighting
lunar
is very
the
if a_-ailable
the
with
to provide
inside
shows
natural
in efficiency
Earth can be utilized (Ehn'cke,
1985).
The location
of the first lunar site
Given
for
or
radiation.
the desired
the potential
space station
habitat
and
of all-artificial
sources
is the
sunlight
to these
shielded
can filter out undesired
transmitting
for any
of using
regolith
illumination.
Third,
the technology
is the only mechanical
device used.
access
outpost
advantages
areas
from
1987).
shown
base
Passive
diagrams
OPTICS
the
Longer-range
threefold.
to transmit
SO systems
Assoc.,
more
to
The
modified
BASE
habitable
protection
provides
a way
menus. Second,
using
space.
are
encapsulate
formations
LUNAR
the
use
several
to the one proposed
the lava tube
THE APPLICATION
for
the
A preliminary
identified
plenum
similar
1985).
can be easily
fluorescent
lamp, and
lamp, the plenum
space
incorporates
advanced
et al.,
but
Figure4
1985).
supplemented
the
The
(Duke
outposts.
Nixon,
Teague
heliostat,
and
lunar
and
preliminary
between
sun's
first
substituting
CELSS module
if the heliostat
is mounted
on the space station
structure
for better solar access, and a lens with the proper
focal
length
the
studies
location
personal
communication,
1988). An opportunity
exists, however,
if the habitat
modules
are used
(Kaplicky
that
the
There
anticipated;
as the
reveal
connection
be
pole
lighting
strategies
modules
favor
and
can
for this
Current
laboratory
guides
volumes
of 50; (3)
HID
HID light
in previous
assume a lunar
latitude.
light
costs
same
hybrid
identified
lamps
of HID
amount
the
by a factor
the
prism
one
light
opportunities
of a remote
calculations
PLG for the fiber optic
device
using
only
of prism
of the
advantages
same
assuming
use
characteristics
the integration
the
evaluated,
The
of development
order-of-magnitude
transfer
were
may offer some
integration
unlike
so that
design,
cables
to consider
optics,
and Space Activities
evaluated.
mass
(1)The
known
PLG can
optic
and
Bases
systems
was
the inherent
reasons
application
material,
lighting
system
system
(2)
on Lunar
-
.
within
is
Eijadi
The
scheme
scale
of
As the
with
lunar
gives
is
SO
Fig. 6
as
is for
is limited
grows,
diagram
shows
a sense
used
in
systems
community
it. The
and
shown
the
of
the
PSO
orientation
both
by
the
illumination
being
to
building-specific
transmitted
a serf-sufficient
only
used
the
colony.
and
The
volumc
scheme
as general
can
grow
with
solar
light
_
\
SOLAR
RADIATION
•
being
_
_
r- HELIOSTAT
ARRAY
TO
| PIPE SUNLIGHT
THROUGH
]
UTILITY
SHAFT
|
_
_
J. (1985)
Space
and
base,
Ehricke
K.
Eijadi
D
(1983)
Conference
PSO
-__-_--v
on
Self-sufficient
Department
HOrz E (1985)
using ASO and PSO.
colony
as
and
Space
412.
Lunar
Kaplicky
J.
ActitSties
SO systems
needed
for
is most
most
filter
been
lunar
module
base.
in this paper
to
deliver
human
appropriate
appropriate
harmful
technologies
CELSS
described
proven
various
for
and
be
for
the
activities
general
for general
radiation.
should
Energy
the
(T
Nixon
system
to
and
known
on
and
Earth.
task
various
for
use
with
Active
development
Both
that
the
of
technologies
quality
illumination,
illumination
only.
It is concluded
considered
the
are
quantity
solar
and
of light
Oleson
optics
PSO
is
systems
can
these
same
space
phases
station
of
the
the
21st
Planetary
M
Report
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177421,
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Bennett
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Multi-Axis
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Controlled
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Cobb
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Proceeck'ngs
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Acti*¢ties
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Space
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a
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Olson
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Illuminating
Walter,
Century
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Systems
Saxe
lunar
of
of the 2Ist
and
Miami
M., and
shelters
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Actim'ties
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Suntracker
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ed.),
Alternate
In Lunar
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Actit$ties
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Civil
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Clean Energy Research
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Miami.
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The
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(W. W. MendeR,
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l r_-_-_._j
I_
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_____.__]
/_;_. •
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II'_
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84. Lunar
PSO
of
optics
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PLATFORM
Applications
To determine the feasibility of applying SO to extraterrestrial
applications, and in particular lunar bases, further investigation as
to the effect of the thermal and ionic environment and of lunar
Burke
RESEARCH
Williams:
dust on the SO sTstem must be undertaken.
illumination
Active
illumination,
horizontally
colony.
available
and
Lighting
E,_dlu,
tton.