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Claims  |
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What is claimed is:
1. A solar power system for use with a space vehicle in orbit, the space
vehicle having a payload bay and, for reference, a .+-.X axis extending in
the direction of orbit, a .+-.Y axis extending to opposite sides of the
payload bay and perpendicular to the .+-.X axis, a .+-.Z axis extending
perpendicular to said .+-.X and .+-.Y axes and through the payload bay,
and, when in orbit, the X-Z plane of the space vehicle coincides with the
orbital plane of the space vehicle, comprising:
a support structure fixed within the payload bay of the space vehicle;
a boom;
means for extending and retracting said boom along the .+-.Y axis;
rotation means for rotating said boom about the .+-.Y axis;
means for attaching said boom to said support structure, and said
attachment means and support structure being dimensioned and arranged such
that said boom has a z-axis level during stowage within the payload bay
which is the same as the z-axis level of said boom when said boom is being
extended and retracted by said extending and retracting means; and
solar panels supported by said boom.
2. A solar power system as recited in claim 1, wherein said boom includes a
first boom section with an inboard end, said first boom section being
adapted for extension by said extension and retraction means out away from
one side of said support structure, and a second boom section with an
inboard end which is adapted for extension by said extension and
retraction means out away from an opposite side of said support structure,
said first and second boom sections being attached to said attachment
means, and said rotation means including drive means to rotate the inboard
ends of said boom sections.
3. A solar power system as recited in claim 2, further comprising first and
second boom canisters and said rotation means including a shaft connected
to and extending between said boom canisters, said first boom section
adapted for stowage within said first boom canister, said second boom
section adapted for stowage within said second boom canister, and wherein
said first and second boom sections share a common central axis with said
shaft.
4. A solar power system as recited in claim 3, wherein said rotation means
rotates said shaft such that said first and second boom sections rotate
synchronously about the .+-.Y axis.
5. A solar power system as recited in claim 1, further comprising storage
means for storing said solar panels in a storage state;
deployment-retraction means for drawing said solar panels from said
storage means and for retracting said solar panels into said storage
means; said boom including first and second boom sections extending to
opposite sides of said support structure; and said power system further
comprising securement means for securing said storage means to an external
end of said first and second boom sections.
6. A solar power system as recited in claim 5, wherein said securement
means comprises first and second beta angle hinges connected to said solar
panel storage means and wherein said first beta angle hinge is connected
to the external end of said first boom section and said second beta angle
hinge is connected to the external end of said second boom section, said
storage means including first and second casing assemblies with each
casing assembly having a first pair of casings pivotably joined to one
another and a second pair of casings pivotably joined to one another, said
casing assemblies further including a mast canister extending between said
first and second pairs of casings in a respective one of said casing
assemblies, and said mast canisters being joined to said beta angle
hinges.
7. A solar power system as recited in claim 6, wherein the casings in said
first pair of casings are adapted for folding one upon another and for
pivoting away from one another so as to further extend along the .+-.Y
axis, and wherein the casings in said second pair of casings are adapted
for folding one upon another and for pivoting away from one another so as
to further extend along the .+-.Y axis.
8. A solar power system as recited in claim 7, wherein said mast canister
of said first casing assembly includes a first portion extending to one
side of said first beta angle hinge and a second portion extending on the
opposite side of said first beta angle hinge and said first portion
extending further away than said second portion, and said mast canister of
said second casing assembly having a first portion extending to one side
of said second beta angle hinge and a second portion extending to the
opposite side, and said second portion extending further out away from
said second beta angle hinge than said first portion such that each pair
of casings in said first casing assembly is laterally offset from each
pair of casings in said second casing assembly whereby the casings in said
casing assemblies, when in a stowage position, extend past one another in
a direction along the .+-.Y axis.
9. A solar power system as recited in claim 6, further comprising
electrical lines extending along said first and second boom sections and
electrically connected to said solar panels, said beta angle hinges having
about (.+-.65.degree.) pivot range, and said electrical line including a
flex cable extending past said beta angle hinge.
10. A solar power system as recited in claim 1, further comprising a
momentum wheel assembly having a momentum wheel adapted for rotation about
an axis parallel to the .+-.Y axis.
11. A solar power system as recited in claim 1, wherein said means for
attachment attaches said boom to said support structure so as to be
non-rotatable about the z-axis whereby there is avoided only development
of a moment about the z-axis due to said boom either before or during an
extension or retraction of said boom along the .+-.Y axis.
12. A solar power system for use with a space vehicle in orbit, the space
vehicle having, for reference, a .+-.X axis extending forward to aft, a
.+-.Y axis extending port to starboard; a .+-.Z axis extending above and
below the space vehicle, and, when in orbit, the X-Z plane of the space
vehicle coincides with the orbital plane of the space vehicle, said solar
power system comprising:
an extendable and retractable boom which, when extended, extends to port
and starboard along the .+-.Y axis of the space vehicle;
a first beta angle hinge connected to a first external end of said boom and
a second beta angle hinge connected to a second external end of said boom;
support means joined to the space vehicle for supporting said boom;
means for attaching said boom to said support means;
means for rotating said boom about the .+-.Y axis;
means for extending said boom from a retracted position to the extended
position;
solar panels;
solar panel storage means for storing said solar panels, said storage means
including a first casing assembly secured to said first beta angle hinge
and a second casing assembly secured to said second beta angle hinge, said
first casing assembly including a first pair of solar panel casings and a
pivot joint pivotably connecting said first pair of solar panel casings
such that a casing in said first pair is foldable onto the other casing in
that pair and adapted for pivoting at the pivot joint about an axis
parallel to the .+-.X axis so as to extend along the direction of the
.+-.Y axis, and said second casing assembly including a first pair of
solar panel casings and a pivot joint pivotably connecting said first pair
of solar panel casings such that a casing in the pair is foldable onto the
other casing in that pair and is adapted for pivoting at the pivot joint
about an axis parallel to the .+-.X axis so as to extend along in the
direction of the -Y axis, and
said first casing assembly including a second pair of solar panel casings
pivotably joined and a mast canister secured to said first beta angle
hinge and extending between said first and second pairs of casings in said
first casing assembly, and said second casing assembly including a second
pair of solar panel casings and a mast canister secured to said second
beta angle hinge and positioned between said first and second pairs of
casings in said second casing assembly.
13. A solar power system as recited in claim 12, wherein said mast
canisters include a first and a second portion and said first portion of a
first of said mast canisters is longer than the first portion of a second
of said mast canisters and the second portion of said first mast canister
is shorter than the second portion of said second mast canister such that
the pairs of casings in said first casing assembly are laterally offset
from the pairs casings in said second casing assembly so that said casings
in said first casing assembly overlap along the Y axis with the casings in
said second casing assembly when said casing assemblies are in a stowage
mode.
14. A solar power system as recited in claim 12, further comprising a
momentum wheel assembly supported by said supporting means, said momentum
wheel assembly including a momentum wheel adapted for pivoting about an
axis parallel to the .+-.Y axis.
15. A solar power system for use with a space vehicle, comprising:
a support base;
an extendable boom positioned within a payload bay of the space vehicle
while in a stowage mode;
attachment means for attaching said boom to said support base;
rotation means for rotating said boom about an alpha axis extending
longitudinally along said boom;
extension means for extending said boom out away from said support base
along the alpha axis;
solar panels;
solar panel storage means for storing said solar panels;
securement means for securing said storage means to said extendable boom;
means for deploying and retracting said solar panels away from and into
said storage means;
said securement means including beta angle hinges for pivoting said solar
panels about a beta axis which beta axis extends essentially perpendicular
to the alpha axis of said boom and in a direction essentially parallel
with the direction said solar panels are extended by said deploying and
retracting means; and
said storage means including pairs of solar panel casings wherein each
casing in a pair is joined by a pivot joint to the other casing in that
pair, and means for unfolding one of the casings in each pair outwardly
along the alpha axis, and wherein said first and second beta angle hinges
are secured to respective external ends of said boom, and said storage
means includes a first mast canister extending between two of said pairs
of jointed casings and secured to said first beta angle hinge and a second
mast canister extending between an additional two of said pairs of jointed
casings and secured to said second beta angle hinge.
16. A solar panel system as recited in claim 15, wherein, for reference, a
z-axis extends perpendicular to said alpha axis and beta axis, and wherein
said support base and said attachment means are dimensioned and arranged
such that said boom has a z-axis level during the stowage mode which is
the same as the z-axis level of said boom when said boom is being extended
and retracted.
17. A solar power system as recited in claim 15, further comprising a
momentum wheel assembly supported by said support structure, said momentum
wheel including a momentum wheel adapted to pivot about an axis parallel
to the alpha axis.
18. A solar power system as recited in claim 15, wherein said attachment
means includes means for jettisoning said boom out of the payload bay, and
said means for jettisoning including means for releasing said boom from
attachment with said support base such that payload doors of the payload
bay are closeable following the jettisoning of said boom out of the
payload bay.
19. A solar power system as recited in claim 15, wherein said support
structure includes a cold plate positioned below said attachment means and
said solar power system further comprising means for cooling said cold
plate.
20. A solar power system as recited in claim 19 further comprising a
plurality of batteries supported by said support structure and in contact
with said cold plate.
21. A solar power system as recited in claim 15 comprising a redundant
power system comprised of solar cells, a shunting unit to control the use
of the power from the solar cells, a battery bank comprised of multiple
cell stacks, and a control and data acquisition computer to manage solar
tracking, battery charging, and battery bank power levels.
22. A method of providing solar power to a space vehicle in orbit,
comprising:
extending a retracted first boom section to one side of the space vehicle
along an alpha axis;
extending a retracted second boom section to the opposite side of the space
vehicle along the alpha axis;
pivoting a first of a first pair of solar panel casings joined to said
first boom section out further away from the space vehicle along the alpha
axis;
pivoting a first of a second pair of solar panel casings joined to said
second boom section out further away from the space vehicle along the
alpha axis; and
deploying said solar panels from said solar casings in a direction
transverse to the alpha axis;
synchronously rotating said boom sections about the alpha axis so as to
rotate said panels to track the sun; and
derotating said first and second boom sections on a dark side portion of
the orbit such that flex cables extending along said first and second boom
sections are unwound.
23. A method as recited in claim 22, further comprising the step of
retaining said boom sections at the same height with respect to the space
vehicle when said boom sections are in stowage and when said boom sections
are being extended.
24. A method as recited in claim 22, further comprising rotating said solar
panel casings about a beta angle hinge connected at the external ends of
said first and second boom sections.
25. A method as recited in claim 22, further comprising rotating said solar
panel casings about a beta angle hinge connected at the external ends of
said first and second boom sections.
26. A method as recited in claim 22, further comprising rotating a momentum
wheel to negate momentum created by rotation of said boom sections.
27. A method as recited in claim 22, wherein said step of deploying said
solar panels includes maintaining the center of gravity of said solar
powered space vehicle at essentially the same place during solar panel
stowage and solar power operation through symmetrical deployment of said
solar power panels from a support base which is fixed at the same height
during deployment and stowage.
28. A method for providing solar power derived from the sun to an orbiting
space vehicle, which, for reference, has a .+-.X axis extending forward to
aft, a .+-.Y axis extending port to starboard, a .+-.Z axis extending
above and below the space vehicle, and when in orbit, the X-Z plane of the
space vehicle coincides with the orbital plane of the space vehicle,
comprising:
placing said space vehicle in essentially a local vertical attitude and
maintaining said space vehicle in essentially the local vertical attitude
by pitching said space vehicle at essentially a constant pitch rate;
deploying boom sections which extend in the .+-.Y direction, and then solar
panels in a direction perpendicular to the direction of extension of the
boom sections;
fixing, in solar inertial coordinates, the deployed solar panels positioned
at the end of the boom sections, while said space vehicle orbits about the
sunlit side of the orbit, by rotating said boom sections about the .+-.Y
axis in a first direction opposite to the pitch rotation and at
essentially the same rate as the pitch rotation;
rotating said boom sections in a direction opposite to said first direction
during a dark side portion of the orbit so as to unwind electric cables
extending along said boom sections;
accelerating a momentum wheel to negate any change in momentum which
develops during rotation of said boom sections in said first direction,
during rotation of said boom sections in said second direction, and to
stabilize and control any minor cyclic pitch excursions of the space
vehicle.
29. A solar power system for use with a space vehicle having a payload bay
comprising:
a support structure fixed within the payload bay of the space vehicle;
a boom;
means for extending and retracting said boom along an alpha axis extending
to the sides of the payload bay;
rotation means for rotating said boom about the alpha axis;
means for attaching said boom to said support structure;
solar panels;
storage means for storing said solar panels in a storage state;
deployment-retraction means for drawing said solar panels from said storage
means and for retracting said solar panels into said storage means; said
boom including first and second boom sections extending to opposite sides
of said support structure; and said power system further comprising
securement means for securing said storage means to an external end of
said first and second boom sections, said securement means comprising
first and second beta angle hinges connected to said solar panel storage
means and wherein said first beta angle hinge is connected to the external
end of said first boom section and said second beta angle hinge is
connected to the external end of said second boom section, said storage
means including first and second casing assemblies with each casing
assembly having a first pair of casings pivotably joined to one another
and a second pair of casings pivotably joined to one another, said casing
assemblies further including a mast canister extending between said first
and second pairs of casings in a respective one of said casing assemblies,
and said mast canisters being joined to said beta angle hinges. |
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Claims |
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Description |
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FIELD OF THE INVENTION
The present invention relates to a solar power system used as a method of
generating electricity for a space vehicle such as the space Shuttle.
BACKGROUND OF THE INVENTION
Presently, the Space Shuttle Orbiters derive electrical energy from "fuel
cells" which chemically combine oxygen and hydrogen to produce
electricity. Fours sets of cryogenic storage tanks containing the oxygen
and hydrogen reactants are normally expended in about eight days at
typical power usage levels.
To extend the duration of an Orbiter mission for more than eight days, it
is possible to utilize additional storage tanks. Indeed, Columbia (OV102)
sometimes carries a fifth tank set to extend the mission by about two
days. For longer durations, it becomes necessary to carry even larger
amounts of reactants for the fuel cells in the payload bay (approximately
400 lbm/day of flight extension). An additional pallet of four tank sets
could be used to increase the mission duration from 8 to 16 days. The
pallet containing the four tank sets, however, adds a mass of about 9000
lb which reduces the weight of the payload that can be lifted into orbit.
The weight of the storage tank sets are such that extended durations
beyond two weeks may not be practical due to the weight of the storage
tanks required for such a mission.
Furthermore, the combination of these reactants contained in the storage
tanks is a highly combustible mixture. A significant safety concern is
thus raised whenever large quantities of the reactants are carried in the
payload bay, especially during launch.
An earlier conceptual design of providing the Orbiter with electricity
derived from solar energy was called a Power Extension Package (PEP). The
PEP featured a solar array package and was carried into space on a pallet
in the Orbiter payload bay. The "Remote Manipulator System" (RMS) was then
used to grapple the array, lift it out of the payload bay and allow the
array to unfold. The array had articulating joints permitting the Orbiter
to assume any arbitrary attitude while the PEP remained pointing at the
sun.
There are several disadvantages inherent in this PEP system. It requires
the RMS to lift the PEP out into space and to maintain it perpendicular to
the sun. To achieve the perpendicular relationship, three articulation
joints had to be adjusted and readjusted upon any shift in Orbiter
attitude. Power transfer took place across all of the rotating joints,
which in turn necessitated complicated wiring systems. The required use of
the RMS, which is not carried on most missions, added weight to the
Orbiter and complexity to the mission. These factors had a very
significant impact on mission cost.
In addition, PEP motion could subject the Orbiter to acceleration forces
which would degrade microgravity conditions. This had the potential effect
of interfering with microgravity experiments or manufacturing processes
being conducted.
U.S. Pat. No. 4,630,791 illustrates a space-based solar operated power
module which also relies on the RMS to deploy, meaning that it also
produced many of the same disadvantages as the PEP.
Moreover, the extension of the solar panel mounting tubes in U.S. Pat. No.
4,630,791 longitudinally along the length of the Orbiter's payload bay has
a highly limiting effect on the size of the cargo which can be stowed. The
stowing of the solar panel mounting tubes longitudinally along the payload
bay can also lead to problems of entanglement between the mounting tubes
and various cargo structures stowed in the cargo bay.
SUMMARY OF THE INVENTION
The purpose of this invention is to provide electrical power to the Space
Shuttle/Orbiter, derived from photovoltaic arrays, which will permit the
Orbiter to fly extended duration missions of 30 days or more. The power
system will utilize the solar cells and batteries in such a way as to
provide the maximum level of reliability and safety. During this extended
mission, the preferred orientation or attitude of the Orbiter is a
"local-vertical" attitude defined as an attitude in which the Orbiter
coordinate directions remain fixed with respect to the "local-vertical" or
zenith-nadir directions. Among a variety of possible "local-vertical"
attitudes, it is preferred that the x-axis is horizontal (nose or tail
pointing in the velocity direction), and the payload bay direction (-z is
either in the zenith or nadir direction. In any local-vertical attitude,
the Orbiter maintains a constant inertial coordinate rotation rate. In the
preferred attitude the entire payload bay is maintained in nearly "0-g" or
weightless condition, free from almost all gravity gradient forces.
The solar panels of the present invention are stowed during launch and
reentry within casings which are supported by a truss-like structure in
the Orbiter payload bay. When the payload bay doors are open, the solar
panel arrays, while remaining folded within the casings, are extended on
booms which protrude beyond the Orbiter wings (y--y direction). The solar
panel arrays are then deployed such that the panels unfold like an
accordion in a direction perpendicular to the boom. In achieving full
deployment of the solar panel arrays an RMS is not required. It is only
after the casings for the arrays have fully extended beyond the wings of
the Orbiter that the panels are deployed from their casings in a direction
perpendicular to the y--y axis of the boom.
With the Orbiter in the preferential local vertical attitude, the solar
arrays can then be rotated about the (y--y) axis to track the sun in a
"solar inertial" attitude. The arrays are fixed in inertial coordinates,
but counter-rotate in Orbiter coordinates at the pitch rate of the
Orbiter. The deployed solar panel arrays continue in steady state rotation
until it becomes necessary to unwind the cables during orbital night time.
An additional "beta-angle" hinge on the array boom allows the arrays to be
tilted to point directly at the sun. The angle of tilt of the array panels
is the same as that which a line to the sun makes with the (x-z) orbital
plane, and is usually referred to as the "beta-angle".
To prevent the cables from winding up tightly, the rotation about the
(y--y) axis, or "alpha rotation" is reversed on t | | |
