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CONVERSION OF SOLAR ENERGY VIA NEW AEROSPACE
TECHNOLOGY
by
J. H. Bloomer., DISCRAFT Corp., Portland, OR 97233
Presented 1994 to IECEC: AIAA/IEEE/ASME/SAE/AIChE/ACS/ANS
(Intersociety Energy Conversion Engineering Conference)
Aerospace technology today would access solar energy in space in any practical desired quantity, and beam
it down to earth for unlimited use in manufacturing, agriculture, housing, education, recreation, science,
astronautics.
Questions are, though: How access solar energy in space? Satellite mirrors driving heat turbogenerators?
Satellite solar cells? Sunpumped lasers? And how deliver the energy to earth’s vicinity? By microwave beam?
By laser beam? How transport the energy down through the atmosphere? Microwave beam? Laser beam?
Power cable? And how pick the energy up on the ground? Rectenna farm? Collector mirror? Cable downlink?
At what cost? Cost to whom? And when available?
This author respectfully submits that a mixture of new and old technologies can satisfactorily solve all
problems, and provide all answers.
For one, lasers, because providing immensely tighter, narrower, longer range beams, must be preferred in
the long run to masers, as most authors agree(1). But laser diffraction-limited transmitter-antenna optics (just
maximum-quality astronomical primaries in large size) have heretofore been very difficult, expensive or
impossible to build – particularly for space. Since ’66, though, there appears to have been a solution
(declassified in ‘65(2)), based essentially on introducing very shallow, static, capillary-boundary-constrained,
reflective, liquid-metal-plated, liquid-plastic pools onto interior surfaces of “rigidized” balloons erected
(inflated) in orbit(3,4,5) somewhat in the fashion of “Echo”(6) (Figs. 1,2,3). These pools in capillary (“zero-g”)
fashion, pull themselves –their own surfaces- into precision optical mirrors (as retouched by deliberatelyintroduced static masses providing “self-gravitation”(7,8) (Fig. 4). Cost-saving of this “hands-off” approach to
retouching, is expected to be immensely superior to that of the essentially real-time “adaptive optics”
method much in the news of late(9).
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Fig. 1. Liquid Surface in Lowered Gravity
N=1
N = 0.5
N = 0.05
N = 0.0

INFINITELY LONG TROUGH
N = VERTICAL LOAD IN G’S
 = CONTACT ANGLE
(WATER)

N
Fig. 2. Liquid Optic in Zero - Gravity
Z-AXIS
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Fig. 3. Error Due to Finite Load
C
R3
F
D

N
= CHARACTERISTIC = /lv
= RADIUS OF MIRROR
= FOCAL LENGTH = R3/2
= APERTURE
= F/D
= LOAD IN g0’S
10
3
D
1
 =  (c,R3,N,D) = ERROR =  1 +  2    Ng 0 C

2
R3
1
2
( g0 =
Ng0
Secondly, no one wants to send even low-intensity
Fig. 4. Liquid Optics Technology Satellite
maserbeams down through the atmosphere – let alone
high-intensity laserbeams(10,11,12). Everyone is quick to
point out that, the narrower and more powerful such
beams are, the more potentially destructive they are
to the environment, to fauna and flora, man and beast.
But narrow beams are required for efficiency in

transmission over interplanetary distances, and that
evidently is required. To add to the problem,
“narrowness” of coherent beams from diffractionlimited primary (maser or laser) optics, is inversely
proportional to the diameter of these optics, while
cost of visible-band (laser) such optics is proportional
to the fourth power of the diameter on earth.
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The author would like to suggest, though, that there appears to be a solution. This solution would permit us
to transmit energy in space by as narrow, and “tight” and powerful a laserbeam even, as we please, but halts
that beam “cold” at the top of the atmosphere (above the clouds).
Balloon-Borne Sea of Solar Cells at 80,000 Ft.
It is simply that we suspend vast fabric –say canvas or equivalent with stiffeners- platforms at, say, 80,000 ft.
altitude from balloons. We might suspend a rectangular such carpet from 4 giant weather balloons attached
one at each corner. Then the carpet upper surface could be covered with the latest and best solar cells(25),
where the latter are matched for efficiency against the wavelength of our space-based – nominally
synchronous-orbiting - liquid-optical laser transmission system. Waste heat rejection at these altitudes
should be facilitated by the fact that even the very thin atmosphere still probably provides enough air for
adequate solar-cell convection cooling. Tether can be umbilical cord carrying power to ground.
Thirdly, investment cost –including life-cycle cost- of all this apparatus and these assemblages for orbit, solar
cells, powerplants, antennas, laser optics, collector-mirrors, spares, repair crews, maintenance crews, etc.- is
going to be high. Particularly for conventional boost-rocket (ex-military) vehicle technology, costs have been
estimated by many as running into the hundreds of millions, a billion or several billions of (’94) dollars (13,14)
per vehicle. Of course space transportation –rocket launch- technology costs are expected to come down
shortly by two orders of magnitude due to such innovations as the SSTO –Single Stage to Orbit- reusable
vehicle. Additionally this author’s proposed “epihydrostatic” (ultra-lowcost, expandable, rigidizable, selfforming) orbital macrolasers supplying solar laser power to electrical rockets all over interplanetary
space(15,16,17) (Fig. 7) should further drastically reduce space transportation system costs while extending their
scope. Debris damage repairs in such large-cross-section satellites in chosen synchronous orbit, will be
minimized by running in advance a broad-viewfield, electro-optical/lasergun, variable-orbit, “sweeping”
satellite, to reduce all significant debris-objects encountered to harmless “space dust” then electrostatically
remove same (permitted by including large “sweeper” onboard – nuclear – power(18).)
Ultimate Boon to Solar Energy Conversion: Free Enterprise
But to reduce the government subsidy in space to zero, and put space developments –both transportation
and utilities- in private hands where they belong, this author suggests we (privately) develop another system,
the VTOL, 5,000-passenger, circular-planform, aerospace SUPERSHUTTLE vehicle (see Fig. 5). Capable of
hauling sightseeing tourists to synchronous orbit and return at a suggested price of $200 per seat,
SUPERSHUTTLE –both VTOL aircraft and beam-climbing spacecraft rolled into one- would operate in the
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atmosphere on “BLASTWAVE”(19) (Fig. 6), LPG-burning jet engines, producing only water vapor as exhaust.
Likewise as spacecraft, SUPERSHUTTLE would accept energy from a synchronous-orbiting, liquid-mirror
macrolaser system, “tightened” beam(20) (Fig. 7), driving its (SUPERSHUTTLE’s) electric rockets, which would
exhaust water vapor again as sole expellant (“steamrockets”).
Fig. 5. Supershuttle
Fig. 6. Pulse Ramjet Blastwave Jet Engine
Predicated on six excursions per day at 3 hours each (reaching Geosynchronous Earth Orbit –GEO- at
approximately 1 g continuous acceleration/braking while “leading” the target sufficiently, might require
about 1 hour, as would of course the return SUPERSHUTTLE –if fully loaded at 5,000 passengers per
excursion- would earn about $1 million gross profit per jaunt to GEO. Presuming net profit of one-half after
expenses, salaries, spares, repairs, maintenance, life-cycle costs, etc., are accounted for –and that perhaps
half the people on the planet might end up as customers –each SUPERSHUTTLE should earn about $1.2
billion per year, net, indefinitely.
Putting SUPERSHUTTLE gross annual revenue of $2.4 billion in perspective, one-quarter this much would be
gained just by selling 747-airplane-proportional, required MACROLASER power at $.05 per kilowatt-hour,
yearlong.
SUPERSHUTTLE powerplant, if proportional to 747’s, would need 10 times the power to haul the (500-seat)
747 payload in air and space. This power would be delivered by a 1%-efficient solar MACROLASER system of
seven miles overall diameter. However 10× that amount might be a safe margin, requiring a solar
MACROLASER system of 22 miles overall diameter.
Passengers would experience very brief periods of very gradually advancing low or zero-g –like fighter-pilotsonce between earth and GEO and once in boarding the (centrifugal, 1 g, rotating) GEO Station (mechanically
independent of the associated –static- MACROLASER).
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Fig. 7. Orbital Macrolaser Tightened-Beam System
1
2
4
5
7
3
8
10
6
9
11
12
13
At the extreme left of the figure is the great solar-collecting mirror (60 miles in dia.), (1). CO2-type macrolaser
is shown symbolically, although in actual fact, a free-electron-type (variable-wavelength in near-infrared and
perhaps 4-5 times more efficient) laser will be used. The great solar-collecting mirror focuses solar energy
onto the semi-silvered collar-like pumping mechanism (9). Energy trapped by multiple reflections in collar (9)
is transferred to the transparent, hollow laser cylindrical cavity (8). Rod (8) is maintained concentric with
collar (9) by strut-supports (10). The laser cavity is filled with a gas which absorbs the reflected solar energy
and “lases”, i.e., transmits a coherent beam normal to the rod’s end-surface mirrors. The end-mirror nearest
the great solar mirror (1) is partially silvered, so that a portion of the coherent energy in the rod continuously
escapes. The “escaping” beam is diverged by “secondary” lens (6). The latter is rigidly attached to laser-rod
(8) and “pump” (9), by strut-supports (7). The diverged coherent beam (4) illuminates the large (1-milediameter) liquid-surface primary mirror (3). High-precision “primary” (3) is bordered by a rigid plastic-foam
boundary-ring (2). Laser energy (5), focused by reflection from primary (3), passes through the empty interior
of collar (9) and emerges in the form of focused high-energy coherent beam (11). The beam (11) supplies
energy at or near its focus to disc-like craft (12), which might carry a protected payload as shown at (13).
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Permanent Balloon-Borne Space Gate at 80,000 Ft
Again to exclude power beams entirely from entering the atmosphere, SUPERSHUTTLE would begin and end
each trip to GEO only at one of the 80,000-ft-high, balloon-borne, carpets. Carpet would be reachable from
anywhere on earth by SUPERSHUTTLE operating as a VTOL/amphibious/cruise “conventional” chemicalpowered –albeit circular-planform or disc (saucer) shaped- aircraft. The disc-shape is convenient for efficient
absorption of energy diffraction-disc (focal spot) of the cooperative macrolaser, earth-going beam,
dispatched from synchronous orbit above. Main purposes of SUPERSHUTTLE might be, spectacular symbol to
popularize spaceflight (advertising), plus that of testing the entire concept of “epihydrostatic” macrolaser
(probably sunpumped CO2(21)), power-beaming, cooperative satellites.
Permanent, 7-Terawatt, Space-Based, Solar Orbital Utility
A self-boosted orbital solar (probably sunpumped CO2(21)) macrolaser utility-power system –boosted
exponentially in stages under its own (collected solar) power and circumferentially assembled(17)
(continuously via astronauts and robots) in orbit (Fig. 8) –would reach 500 miles (collector) diameter in
about 310 days from 200,000-lb LEO “seed” at starting (collector) diameter of 1 mile (if its exponential
growth rate is 1/80th per day).
Fig. 8. Orbital Macrolaser
System Construction
Such a (500-mi.-diameter)
system, at characteristic 1%
efficiency, would deliver on
the
ground
about
7
terawatts of power. This is
perhaps
comparable
to
earth’s total present power
consumption
from
all
sources combined –coal, oil,
hydro, nuclear.
Delivery of this power level continuously for one year at a standard rate of $.05 per kilowatt-hour, would
earn about $3 trillion gross profit.
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The Solar Power Satellite
The (microwave) Solar Power Satellite concept(10,11,12) has since ’68 fired the world’s imagination as perhaps
no other space project since “Apollo”. However, the cost context of the (microwave-beaming) SPS is truly
discouraging in prospect. For example, launch vehicles in the West are characterized by yearly operating
costs from $1-$5 billion (fixed & recurring) and operational costs from $60-$1000 million per flight(14). SPACE
SHUTTLE missions today cost about $1/2 billion each and weigh about 200,000 lb, whereas SPS will –for a 5gigawatt system- weigh 1,000 times as much as SPACE SHUTTLE or at least 100,000 tons. Thus at the same
per-pound value, a single 5-GW SPS will be worth at least $1/2 trillion. Actually, infrastructure costs for SPS
will drive this figure much higher(14). Since it’s proposed to build a whole fleet of SPS’s simultaneously –say 6then we could be looking at a minimum on-line cost for these six of at least $3 trillion. But MACROLASER
system above, delivering 7 TW, if –mostly membranous- materials, and crews could be provided fast enough,
could fuel itself into orbit and be fully on-line at the end of a year, furnishing $3 trillion/yr worth of power. Six
SPS’s would cost $3+ trillion to build, might require 10 yrs. to build, and would furnish ½% as much power as
one MACROLASER system.
Space experts and engineers agree that low-cost SSTO rockets operating much like conventional aircraft,
would reduce the cost of transportation into space by at least 2 orders of magnitude(13). But of course space
transportation is only one of the costs of SPS. Too SSTO projects are undergoing “tough sledding” in Congress
–and well perhaps they should be; perhaps they shouldn’t need to be funded any longer by Congress anyway.
Present proposal shows significant U.S. Government subsidy to the aerospace industry is probably obsolete,
unnecessary and retrogressive.
Critical experiments in Liquid Space Optics
Experiments are needed on: potential spacecraft outgassed monolayer effects changing liquid-metal surface
tension, variable surface tension effects on optical image or laserbeam collimation, ripple or vibration effects
on optical surfaces, attitude-control system (probably using RRC(22) subliming propellant microrockets)
effects, high-power laserbeam heating effects on optical-surface tension, quality, etc. Experience to date
evidently is only with dynamic (rotating) liquid-metal systems of (paraboloidal) astronomical optics, such as
R.W. Wood’s mercury experiments in 1908(23) and Ermanno Borra’s electro-optical experiments of 1993 on
same type apparatus(24).
Elementary experiments on static liquid optics systems, might begin with ground-based simulation tests
using the experimental apparatus shown in Fig. 9, essentially meant to create and test and artificial zero-g,
liquid-metal, “capillary epihydrostatic”, optical surface (G). Density of clear, contained liquid (E) is precisely
matched to density of reflective liquid metal (H) such as to create precision concave mirror (G), where mirror
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radius of curvature is determined by (fixed) contact angle on toroidal boundary-surface, (F). Zero-g drop tests
from a tower might be performed with equipment such as the Northrop apparatus shown in Fig. 10, drop
time was 2.2 seconds. A more elaborate drop-test is shown in Fig. 11, consisting of a capsule for balloon-drop
from 80,000 ft. Droptime was about a minute. High flying aircraft have been put in parabolic arc to provide a
certain amount of zero-g test time. Liquid space optics’ ultimate testbed is a “Liquid Optics Technology
Satellite” (LOTS) as shown in Fig. 4, provided with both reflective and refractive liquid optics and a
microwave downlink antenna. Latter vehicle, following expansion (inflation) and rigidization from rocket
payload shroud (at bottom of figure), would power internal equipment via thin-film solar cells covering its
exterior (spherical) wall(12,25).
Fig. 9. Optics Zero-g Simulation via Matched Liquid Density
J
F
A
C
Q
B
I
G
E
5”
R
D
H
K
A
F
1”
S
T
L
M
O
“1”  FORWARD
“0”  REVERSE
L
10
10
P
Page 10
Fig. 10. Optics Zero-g Short-Free-Fall Test
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Fig. 11. Optics Zero-g Long-Free-Fall Test
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REFERENCES
1. Toussaint, M., “Energy Transmission in Space; An Enabler Technology,” SPS 91 Power From Space
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2. Military Secrecy Order, implemented June 15, 1965 by USAF on “Space Telescope” subject-matter of
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1964.
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