Patent Description:
All scenarios of warming of the earth's atmosphere discussed of the IPCC (Intergovernmental Panel on Climate Change) shown a temperature increase of <NUM> degrees or more beyond the level of the preindustrial age in every possible scenario.

There have been discussed many environmental engineering concepts that could potentially stop or slow down the increase of the atmosphere's temperature, such as simulating a volcanic eruption. This involves bringing sulfur particles into the stratosphere, which then reflect solar radiation and cause the average temperature on Earth to drop by half a degree for a short time. However, such an intervention would have significant side effects: The sulfur particles could damage the ozone layer and the temperature difference between the tropics and the poles would decrease. Moreover, such a process would not be reversible.

Another idea is based on blocking solar radiation from the earth and thus stopping global warming. The ideas range from giant sunshades to mirrors in space that would reflect the radiation. However, the costs are immense - and the implementation is not feasible due to the associated immense mass of such mirrors.

Thus, while in principle the idea of placing a mirror or a lens in the path between sun and earth is not new and actually is common knowledge, an actual solution has always been completely unrealistic when looked at in detail. The present application describes a solution required to reduce the incident solar energy on Earth. The here presented concept is technically highly challenging and costly, but nevertheless the only feasible solution for a global control of solar irradiation in a reversible manner. <CIT> discloses a polarization element having good polarization properties and being excellent in heat dissipation property and manufacturing costs. In order to solve this problem, a polarization element is provided that includes a substrate made of a transparent inorganic material, a grid structural body which is made of a transparent material and that includes a base portion provided along a surface of the substrate and protruding portions protruding from the base portion in a grid, and an optical functional layer which is formed on the protruding portions, and includes an absorptive layer for absorbing light, a reflective layer for reflecting light, or a multilayer having at least the absorptive layer and the reflective layer.

It is therefore the object of the invention to provide an improved foil and foil assembly for shading the earth.

The present invention relates to a concept of shading the earth by providing a foil and an arrangement of multiple foils that efficiently prevents solar flux from reaching the earth. At the same time, the present invention minimizes the weight of such foil and arrangement by combining multiple physical effects.

According to an aspect of the present invention, a foil is provided. The foil may comprise a carrier substrate and a (or an arbitrary) line pattern of vapor deposited aluminum layer on the carrier substrate. The carrier substrate may be ultrathin and may be made of a material that is substantially transparent for visible light, specifically due to the minimizes thickness. The line pattern may be an alternating pattern of first beam-shaped areas and second beam-shaped areas. Only the first beam shaped areas may be comprised of the aluminum layer on the carrier substrate. The second beam-shaped areas may be punctured to reduce weight of the foil. The aluminum layer may have a thickness of one atomic layer of aluminum.

Further, an assembly of multiple foils described herein may is provided for shading the earth. The assembly may comprise a plurality of foils, which are relatively positioned to each other in a predetermined arrangement. The assembly may further comprise a plurality of strings for connecting the plurality of foils to assemble the assembly in a predetermined arrangement. The assembly may be configured to interact with incident light from its path from the sun towards the earth by (a) partially reflecting the incident light, (b) partially absorbing the incident light and re-emitting it uniformly, and (c) partially Bragg diffracting the incident light. The mass of the assembly and the size of an effectively irradiated area of the assembly may be configured such that the assembly is in a force equilibrium of gravitational forces and photon pressure when arranged and positioned at a predetermined position between the earth and the sun.

Embodiments and aspects will be described in the following description and together with the accompanying drawings, wherein.

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings.

With the planet warming up and thus extra emitted radiation and with extra losses through clouds etc., an extra solar absorption of approximately <NUM> W/m<NUM> is given, compared to an average absorption of <NUM> W/m<NUM> on earth, which is <NUM>% of the incident solar flux calculated for the current imbalance, which is about <NUM> degree at the moment. A very similar number comes from the naïve estimate of a <NUM> influence of solar radiation on the earth's temperature. A reduction of <NUM> degree would correspond to <NUM>% reduction of solar flux.

The basic concept of the invention is the placement of a means for reduction of solar irradiation between earth and sun, close to the Lagrange Point L1, more than <NUM> Million km away from the position of the earth directly in the direction of the sun. The duration of the orbit of an object placed in L1 is synchronous with the earth. However, the object would require active control, as the position is not stable.

Any object in L1 reduces the flux of photons on the earth's surface. An object with the cross section <NUM> x <NUM> x π = <NUM>. 3x10<NUM> m<NUM> would produce shade on the whole earth. A reduction of <NUM> degree would thus correspond to reducing the flux by <NUM>/<NUM>, or placing a dark spot of <NUM>. 8x10<NUM> m<NUM> close to L1.

The above described concept, however, comes with challenging problems. Any known technical solution so far would fail because of the mere dimension and therefore mass of this object, which prevents implementation on the position because of transporting it there. Further, a solar sail with more than <NUM><NUM> m<NUM> feels a lot of photon pressure acting on it. While this is no problem for most satellites, here the size and the very low intended mass would cause massive acceleration of the object due to photon pressure.

The present invention and the herein described inventive concepts solve these problems in an efficient manner as will be discussed in more details. The basic idea of the present invention suggests a material, which deploys different effects to reduce light reaching the earth. Further, the geometrical arrangement of the material causes the arrangement to actually stay in position as a shield and its availability.

<FIG> show exemplary arrangements of a foil that may be used according to an aspect of the invention. The foil <NUM> as illustrated is only for providing a better understanding of the structure of the foil <NUM> and the illustration is not to scale. Further, the exact geometry of the components in <FIG> are for illustrative purposes only and may differ from the actual geometry of the foil <NUM>.

The foil <NUM> comprises a carrier substrate <NUM>. The carrier substrate <NUM> may be made of formvar material or nylon and has a thickness in the range of <NUM>. Techniques for producing carrier materials <NUM> with less than <NUM> thickness exist and are state of the art.

The basic idea of production of the carrier substrate <NUM> is similar to making nylon: two liquids are placed in a bath on top of each other. The liquids do not mix and form a chemical reaction on their contact surface, which solidifies. If one pulls on this layer with a specified velocity, the thickness of the layer can be defined. This method can be arbitrarily scaled and an infinite length foil with a width defined by the maximum bath width can be produced.

The production of the material can be scaled up from this technique to an infinite length and even up to kilometer-scale wide sheets can be produced with a machine of sufficient width.

However, the above technique is only one possibility for producing the carrier substrate <NUM> and other techniques may also be sufficient to produce such ultrathin foil. An alternative technique may be stretching. Stretching techniques exist, where commercially available polypropylene films may be stretched to thicknesses in the range <NUM>-<NUM>. Such films are used as windows for soft x-ray proportional counters, gas absorption cells, energy-loss nuclear detectors, and high vacuum isolation.

The invention is not limited to a specific carrier substrate <NUM>, but it is advantageous to use a substrate that is particularly thin, particularly light, particularly stable and interacts only minimally or not at all with electromagnetic waves in the visible spectrum.

Directly from the production line, after the carrier substrate <NUM> dries and before it gets rolled for storage, the carrier substrate <NUM> may get punctured by patterned laser-light with typically <NUM> micrometer dimension to reduce the mass of the material by <NUM>%. As can be seen in <FIG>, punctures <NUM> are arranged in the carrier substrate <NUM> along a beam shape. The carrier substrate <NUM> is substantially transparent to visible light and beyond, i.e. substantially transparent for light with wavelength within the range of <NUM> and <NUM>.

In the non-patterned parts of the structure, aluminum structure with <NUM> spacing between <NUM> strips may be vapor deposited in a continuous foil-throughput machine with a thickness of <NUM>, which corresponds approximately to one atomic layer of aluminum.

Vapor deposition for plastic foils is industry standard e.g. for super-insulation foils: Here, the carrier substrate <NUM> may be guided into and out of a vacuum chamber with entrance and exit slits for the foil. Inside the chamber, aluminum vapor is produced through heating. The vapor deposits on the carrier substrate <NUM> and forms an optically thick layer, which may be a thickness of one atomic layer of aluminum.

In other words, a line pattern of vapor deposited aluminum layer <NUM> may be built on the carrier substrate <NUM>. The line pattern may be seen as an alternating pattern of first beam-shaped areas and second beam-shaped areas. Only the first beam shaped areas may be comprised of the aluminum layer <NUM> on the carrier substrate <NUM> and the second beam-shaped areas may be punctured to include holes <NUM> to reduce weight of the foil <NUM>. In an exemplary embodiment, the alternating pattern of the first and second beam-shaped areas comprise a width within a range of substantially <NUM> to <NUM>.

Alternatively, the laser punctures or holes <NUM> may be produced after the carrier substrate <NUM> is vapor deposited with the aluminum layer <NUM>, thereby removing the aluminum layer <NUM> along the second beam shaped areas. As such, the second beam shaped areas may be simply the areas, where the punctures are located.

The foil <NUM> combines the physical effects of absorption of light (several percent), reflection of light (<NUM>% or less, depending on the patterning and structure of the aluminum) and Bragg diffraction (rest), depending on the patterning. As such, the patterning of the aluminum layer makes the foil <NUM> a combination of a mirror, an absorber and a Bragg grating.

An exemplary alternative realization could be parallel aluminum strips or a crossed pattern. Such composition may use thin layer reflection properties of aluminum together with diffraction properties of the aluminum fabric. in such alternative realization, no carrier substrate or at least less carrier substrate may be required.

Referring back to <FIG>, as discussed, the areas without aluminum layer <NUM> are substantially transparent for visible light. These areas may be areas, where light hits directly on the carrier substrate <NUM>, i.e. where no aluminum layer <NUM> is present, or where light passes one of the punctures <NUM>. Based on the given geometry and the spacing of the aluminum layers <NUM> and/or the punctures <NUM> on the substrate <NUM>, Bragg diffraction occurs and the light that passes the foil <NUM> is diffracted similar to light passing an a diffraction grating, which is an optical component with a periodic structure that diffracts light into several beams travelling in different directions.

Here, the spacing of the aluminum layers of <NUM>-<NUM> micrometer results in <NUM> degrees for <NUM> and <NUM> degrees for <NUM> deviation of the light beam for the zero-order maximum. At more than <NUM> Million km distance to the earth, this light does not reach the earth's surface.

Combining the effects, dimensions of the assembly can be estimated. The surface of <NUM>. 8x10<NUM> m<NUM> is multiplied with <NUM>/<NUM> for residual transmission and with <NUM> for the mass reduction due to laser punctures <NUM>. With a density of <NUM>/m<NUM> for the carrier substrate <NUM> and <NUM>/m<NUM> for the aluminum <NUM>, a mass of <NUM> tons is calculated.

While this number is massive for space transport, with a payload of approximately <NUM> tons per flight for this distance using a SpaceX Falcon heavy rocket, this results in <NUM> starts, or <NUM> starts for the SpaceX starship, which can in principle done within one year, compared to more than <NUM> needed flights using a conventional mirror foil. While these are massive numbers, in comparison to all other technical solutions this is at least an order of magnitude smaller and compares to a number of starts which has easily been accomplished by mankind in the past and can in principle be realized in a time-scale matching the need to reduce global warming.

A conceptual diagram of an assembly <NUM> comprising a plurality of foils <NUM> is shown in <FIG>. The assembly <NUM> as illustrated in <FIG> is highly simplified and only gives an impression of a possible outer geometry of the assembly <NUM>. In more detail, the outer shape of the assembly <NUM> may be comprised of a plurality of foils <NUM> that are arranged such that their surfaces are substantially directed towards the sun. Further details regarding the relative positioning of the plurality of foils <NUM> can be seen in <FIG>. Notably, the assembly <NUM> may either be the whole construction connected together, or the assembly <NUM> may be only a subpart of the whole system, e.g. the assembly may be a subset of foils <NUM> which are combined to be a partial unit in the whole system. In the second case, there may be a plurality of assemblies <NUM> that build the surface of the whole construction.

As can be seen in <FIG>, the assembly <NUM> may be placed near the Lagrange point L1. The L1 point lies on the line defined between the sun and the earth. It is the point where the gravitational attraction of the sun and that of the earth combine to produce an equilibrium. Due to the photon pressure force caused by the sun light incident to the foils <NUM>, the assembly <NUM> is not placed on the exact position of L1 but is placed closer to the sun, such that the assembly <NUM> is in a force equilibrium of gravitational forces and photon pressure when arranged and positioned at this predetermined position.

In order to span the plurality of foils <NUM> and to assemble the assembly <NUM>, the foils may be connected by strings (not shown) and the whole assembly <NUM> rotates around axis <NUM>. In this manner, no frame is required for spanning the individual foils <NUM>, but the centrifugal force resulting in the rotation spans the foils that are connected by strings.

The sun light <NUM>, when incident on the assembly <NUM> will be mainly mirror reflected or Bragg diffracted such that the light does not reach the earth <NUM> as conceptually shown in <FIG> as light rays <NUM>.

Heating of the material by the sun is not an issue, as the heat conductivity from front to back side is very high due to the small thickness, which causes the heat to radiate away efficiently on the shaded back side.

As stated above, an important aspect is the massive momentum transfer of incident solar flux, which causes a Mega-Newton force on the whole surface, which results in significant acceleration due to the extremely minimized mass. The photon pressure is <NUM>-<NUM> N/m<NUM>, amounting to <NUM>. 8x10<NUM>N for the whole surface, if it is placed like a solar sail. Typical forces from gravity and centrifugal force are almost <NUM> times smaller. To therefore control the motion of the objects, the photon pressure must be reduced accordingly.

The invention provides a solution to this problem by providing a stacked arrangement of the foils <NUM> in the shape of stairs, connected by strings. An exemplary scheme of the geometry and relative posture and positions of foils <NUM> can be seen in <FIG>. With this geometry of the assembled foils, the solar-sail effect can be minimized sufficiently and effectively the solar-sail effect is almost fully canceled.

As can be seen in <FIG>, light beams <NUM>, <NUM> and <NUM> are incident on foils 100a, 100b, and 100c, respectively. Following light beam <NUM>, the light reaches the front surface of foil 100a. From the front surface of foil 100a, the light beam <NUM> is reflected as light beam <NUM>' onto the back surface of neighboring foil 100b. Notably, the foils 100a and 100b are not arranged to each other in an exactly parallel manner, but are relatively inclined to each other by a small angle. In this manner, the light beam <NUM>' that reaches the back surface of the neighboring foil 100b is reflected by the foil 100b as light beam <NUM>". Due to the small angle between each of the neighboring foils <NUM>, the light beam <NUM>" is not parallel to the initial light beams <NUM>, <NUM>, and <NUM>, but is deflected in such a way that it misses the earth, as can be seen as angle <NUM> between the reflected beam <NUM>" and the direction of light beams <NUM>, <NUM>, <NUM>.

At the same time, the photon pressure caused by the light beam <NUM>' hitting the back surface of foil 100b almost cancels the photon pressure caused by incident light beam <NUM>, such that the total force caused by the photons from the sun is minimized.

In this way, most of the light is effectively not reflected back into the direction of the sub, but rather passed on with a slight deviation due to minor angular mismatches, to miss the position of the earth. By the symmetric arrangement (e.g. rotation symmetric) of several sets of stacked foils <NUM>, the transverse forces can be canceled if needed without losing efficiency in surface coverage.

With the foil <NUM> representing relatively well aligned surfaces by themselves, it is in principle possible to direct the light from each foil <NUM> or foil panel in a purposely chosen direction. This means, the Bragg diffracted light may be guided into a specific direction for each color, as well as the light reflected from the stack of foils.

Thus, there is a possibility to produce "focus regions" in space, where either white light from different foil panels is superimposed to increase the power density from <NUM> W/m<NUM> by more than a factor of <NUM>, only limited by the alignment quality. With a plurality of individually controlled foil stacks, such as several hundreds of them, in place to form the large surface together, their individual alignment mechanisms enables this procedure.

Use of this light power for in-space manufacturing may be implemented as follows: by placing focusing mirror optics (e.g. superinsulation foils etc.) of a predetermined size (e.g. <NUM><NUM>) in such a focus volume, e.g. placed in the L1 region, a power density in the magnitude of GW/m<NUM> may be obtained. Such power densities may be used for melting and evaporating of materials to be used in space similar to a vacuum furnace, or to pyrolytically process fuel ingredients for interstellar space travel. One possibility may be shooting the material to be processed in the form of a beam of macroscopic particles, ice, or gas through the region and collect it afterwards again.

Another possibility may be the spatial overlay of wavelength ranges from Bragg diffraction to form volumes in space with increased power density of up to MW/m<NUM> at specifically selected light wavelengths. Applications of such a volume in space could be higher specialized processing, e.g. chromatographic separation of materials, isotope enrichment or spectroscopy.

An alternative implementation of the foil <NUM> and an assembly, which is also remotely controllable but possibly consists of less elements can also be placed in a geostationary or solar-synchronous orbit around the earth, or in an orbit following the moon. Using the deflected light from the foil <NUM>, the light may be targeted on a predetermined and controllable area, such as several square-kilometer sized focus, on the earth's atmosphere to heat up air aiming to stop hurricanes or similar weather phenomena. For example, an approximately <NUM><NUM> sized foil assembly may be used to produce a <NUM><NUM> sized focus with a power density of <NUM> times the normal sun light. Notably the size of the foil assembly may also be bigger or smaller, depending on the use case.

By pointing this high intensity light source with e.g. <NUM> kW/m<NUM> for an exposure time of one hour on clouds of an unwanted weather phenomenon over open sea, the dynamics of a storm may be massively altered: an optically thick layer of water can be evaporated within seconds. A cloud contains up to <NUM> water per m<NUM>. With a heat capacity of <NUM> J/kg/K, the light needs <NUM> to heat this amount of water by <NUM> degrees. With a cloud thickness of e.g. <NUM>, the laser would fully vaporize a heavy cloud in one hour and completely change the dynamics of a hurricane due to the convection behavior and rapid transport of the hot vapor.

As such, the foil <NUM> as disclosed herein may not only be used for manufacturing the assembly <NUM> for shading the earth, but many different application areas are given.

In the following, this application describes the specific requirements and architecture of the assembly <NUM> for shading the earth, i.e. the assembly <NUM> as it may be placed near the Lagrange point L1.

The assembly <NUM> for shading the earth may include the following components and the following structure. The assembly may comprise a plurality of foils <NUM>, which are relatively positioned to each other in a predetermined arrangement. The foils comprise the carrier substrate <NUM>, which is substantially transparent for visible light. Further, the foils <NUM> each comprise a line pattern of vapor deposited aluminum layer <NUM> on the carrier substrate <NUM>. The line pattern is an alternating pattern of (i) first beam-shaped areas and (ii) second beam-shaped areas. Basically, only the first beam shaped areas are comprised of the aluminum layer <NUM> on the carrier substrate <NUM>. The aluminum layer <NUM> may have a thickness of one atomic layer of aluminum. The second beam-shaped areas are punctured to reduce weight of the foil <NUM>. The assembly may further comprise a plurality of strings for connecting the plurality of foils <NUM> to assemble the assembly <NUM> in the predetermined arrangement.

The assembly <NUM> may be configured to interact with incident light from its path from the sun towards the earth by (a) partially reflecting the incident light, (b) partially absorbing the incident light, and (c) partially Bragg diffracting the incident light.

The mass of the assembly <NUM> and the size of an effectively irradiated area of the assembly <NUM> may be configured such that the assembly <NUM> is in a force equilibrium of gravitational forces and photon pressure when arranged and positioned at a predetermined position between the earth and the sun.

The assembly <NUM> may be comprised of multiple subsets of assemblies comprising the stepped arrangement as illustrated in <FIG>. The individual assemblies may be relatively small (several kilometers in size to enable the use of off-the-shelf strings without excessive forces). Unfolded deployment of the material may be ensured by applying angular momentum to the respective assemblies of stacks. In an embodiment, the assembly may be rotation-symmetric. The angular momentum may be applied during remote installation.

For an ordered alignment of the assembly <NUM>, the centrifugal force may be necessary, which may be achieved by a rotational momentum of the entire arrangement, i.e. of all subsets of the assembly <NUM>. The arrangement can be chosen relatively freely, as long as the foils rotate around a common center of gravity. The symmetry axis of the whole construction may be defined as the common center of gravity of the assembly, i.e. of the plurality of foils.

The rotation may then be used to spread out the foils <NUM> and stabilize the structure. In an embodiment, two opposite assemblies of foils with different shape but same dynamic inertia may also work and it is not required to have a rotation-symmetric geometry.

As discussed above, implementation of the assembly <NUM> may be a placement slightly beyond L1, so that there is gravitational drag towards the sun and a different orbit duration. These effects are then counteracted by aligning the material with an angle to purposely use photon momenta not only to balance the forces but also to stabilize the position actively.

With balanced forces between gravitational drag, orbital acceleration and photon pressure, control of an assembly is done using conventional thrusters or propulsion devices at the installation, which is stabilized using strings. The actual force is then applied by the photon pressure itself, which then acts on the rotated structure of the assembly <NUM>.

The individual assemblies of foils <NUM> may be placed independently over a volume in free space of approximately the size of the earth's cross section or larger, as the central region of the sun is the relevant parameter and not the earth.

Claim 1:
A foil (<NUM>) comprising:
a carrier substrate (<NUM>), wherein the carrier substrate is substantially transparent for visible light;
a line pattern of vapor deposited aluminum layer (<NUM>) on the carrier substrate, wherein the line pattern is an alternating pattern of (i) first beam-shaped areas and (ii) second beam-shaped areas, wherein only the first beam shaped areas are comprised of the aluminum layer on the carrier substrate, characterized in that:
the second beam-shaped areas are punctured to reduce weight of the foil, and
the aluminum layer has a thickness of one atomic layer of aluminum.