Moon Umbrellas
The question of solar power during the lunar night has again come up.
Not being a scientist, and in fact, reading Catch-22 during my high school science classes, I hesitate to speak up. However, has anyone thought of controlling the sun’s flux by reflectors and umbrellas. We constantly use these techniques to control light in recording television and films and there is no reason they can’t work on the moon.
Place a solar reflector at a point in space where the push of the sun’s flux is balanced by the moon’s gravity. Bounce the sunlight onto the solar panels at the Moon Base during the night for continual power. Then it doesn’t matter where you place the moon base.
Bounce the sunlight during the day to double the available power.
The reflector could be thin film mylar. There is no atmospheric drag to deflect it. It could be curved to focus it or convexly curved to provide a broader, lower power over a large area, say to illuminate night exploration. By controlling the curvature and angle you could provide the requisite power for any need. You could power roving exploration vehicles from space by simply covering them with a moving beam. The panels could also serve as radio relays.
You could also place an umbrella between the sun and the moon surface to shield the base from the heat of the sun during working hours, to lower the temperature on equipment and people. A half-silvered reflector could control the amount of sunlight passing to give you any required temperature.
Placing more substantial umbrellas, made of compacted regolith or basalt, you could shield the moon base from nasties, such as gamma rays and solar flares, lower the radiation burden on the base, and extend the time for human surface activity.
In fact, moon umbrellas could serve as mini, movable atmospheres in protecting moon bases and controlling the sun’s power and other radiation. It would make it possible to live on the surface in domed cities with a view of the earth, moon surface and stars, rather than underground in lava tubes.
Could somebody with an actual degree help me out with this?
Thanks,
Chippro
Not being a scientist, and in fact, reading Catch-22 during my high school science classes, I hesitate to speak up. However, has anyone thought of controlling the sun’s flux by reflectors and umbrellas. We constantly use these techniques to control light in recording television and films and there is no reason they can’t work on the moon.
Place a solar reflector at a point in space where the push of the sun’s flux is balanced by the moon’s gravity. Bounce the sunlight onto the solar panels at the Moon Base during the night for continual power. Then it doesn’t matter where you place the moon base.
Bounce the sunlight during the day to double the available power.
The reflector could be thin film mylar. There is no atmospheric drag to deflect it. It could be curved to focus it or convexly curved to provide a broader, lower power over a large area, say to illuminate night exploration. By controlling the curvature and angle you could provide the requisite power for any need. You could power roving exploration vehicles from space by simply covering them with a moving beam. The panels could also serve as radio relays.
You could also place an umbrella between the sun and the moon surface to shield the base from the heat of the sun during working hours, to lower the temperature on equipment and people. A half-silvered reflector could control the amount of sunlight passing to give you any required temperature.
Placing more substantial umbrellas, made of compacted regolith or basalt, you could shield the moon base from nasties, such as gamma rays and solar flares, lower the radiation burden on the base, and extend the time for human surface activity.
In fact, moon umbrellas could serve as mini, movable atmospheres in protecting moon bases and controlling the sun’s power and other radiation. It would make it possible to live on the surface in domed cities with a view of the earth, moon surface and stars, rather than underground in lava tubes.
Could somebody with an actual degree help me out with this?
Thanks,
Chippro
9 Comments:
Thanks for your questions - a few comments:
First, the endless supply of sunlight will give rise to a variety of methods and mechanisms to harness this highly valuable source of energy from the Sun -- and mirrors in space will undoubtedly find many applications.
David Criswell has written about reflectors in Earth orbit for directing lunar-generated microwave energy to sites on the Earth (depicted in the Moonbook, Figure 6.1, page 89). Also, reflectors in space have been suggested for transmitting energy from one location on Earth to another.
I suspect that giant mirrors will be used for directing sunlight to desired locations on the Moon (lunar orbits are mostly unstable, but that can be overcome with solar sail navigation techniques) as you mentioned. In my Moonbook, we discussed solar sails (which are mirrors) for transportation; we also mentioned using them in stationary orbits above the north or south pole of a planetoid (such as Mercury and Mars) to serve as data relay points. The key to lunar base siting is power and direct communications with Earth (Malapert Mountain is optimum initial site in this respect). The key to lunar development is to begin with the first (limited capability) lunar base, THEN construct power / communication / transportation networks around the circumference of the Moon (polar region are preferred due to less construction effort and cost), THEN, by being connected into the continuously energized power, communication, and transportation grid, every location on the Moon will be available for exploration & settlement.
On the Moon, sunlight is desirable for power and solar oven applications, so I don't think we will be using solar umbrellas for shade in the near future. All equipment that does not absolutely need to be on the lunar surface will go underground because the underground environment is far less hazardous for every kind of equipment - same thing applies to people. Most of the work done on the Moon by humans will be underground or in structures that have tons of overhead regolith shielding.
Along that line, I foresee the use of 1000's (or millions) of giant sails in orbit around Venus -- their purpose would be to block sunlight and permit the atmosphere of Venus to cool to the point that life forms could exist. We could then bring in water from comets (and Jovian moons) and transform Venus into a livable planet... Someone should make a video about these ideas!
Having a transparent radiation umbrella on the Moon would be terrific -- no one wants to be a mole. Difficulty is that very thick glass (transparent) structures that mitigate radiation hazards and also provides a window to the universe may not be possible. My guess is that people will live in large (volumes on the order of 100-1000 cubic miles), very comfortable underground malls. By that time, technology should be advanced to the point that the ceiling of such structures could be made of TV screens that depict exactly what one would see if the protective dome were not there (including a real time, dynamic view of the Earth).
Thanks,
David Schrunk
First, the endless supply of sunlight will give rise to a variety of methods and mechanisms to harness this highly valuable source of energy from the Sun -- and mirrors in space will undoubtedly find many applications.
David Criswell has written about reflectors in Earth orbit for directing lunar-generated microwave energy to sites on the Earth (depicted in the Moonbook, Figure 6.1, page 89). Also, reflectors in space have been suggested for transmitting energy from one location on Earth to another.
I suspect that giant mirrors will be used for directing sunlight to desired locations on the Moon (lunar orbits are mostly unstable, but that can be overcome with solar sail navigation techniques) as you mentioned. In my Moonbook, we discussed solar sails (which are mirrors) for transportation; we also mentioned using them in stationary orbits above the north or south pole of a planetoid (such as Mercury and Mars) to serve as data relay points. The key to lunar base siting is power and direct communications with Earth (Malapert Mountain is optimum initial site in this respect). The key to lunar development is to begin with the first (limited capability) lunar base, THEN construct power / communication / transportation networks around the circumference of the Moon (polar region are preferred due to less construction effort and cost), THEN, by being connected into the continuously energized power, communication, and transportation grid, every location on the Moon will be available for exploration & settlement.
On the Moon, sunlight is desirable for power and solar oven applications, so I don't think we will be using solar umbrellas for shade in the near future. All equipment that does not absolutely need to be on the lunar surface will go underground because the underground environment is far less hazardous for every kind of equipment - same thing applies to people. Most of the work done on the Moon by humans will be underground or in structures that have tons of overhead regolith shielding.
Along that line, I foresee the use of 1000's (or millions) of giant sails in orbit around Venus -- their purpose would be to block sunlight and permit the atmosphere of Venus to cool to the point that life forms could exist. We could then bring in water from comets (and Jovian moons) and transform Venus into a livable planet... Someone should make a video about these ideas!
Having a transparent radiation umbrella on the Moon would be terrific -- no one wants to be a mole. Difficulty is that very thick glass (transparent) structures that mitigate radiation hazards and also provides a window to the universe may not be possible. My guess is that people will live in large (volumes on the order of 100-1000 cubic miles), very comfortable underground malls. By that time, technology should be advanced to the point that the ceiling of such structures could be made of TV screens that depict exactly what one would see if the protective dome were not there (including a real time, dynamic view of the Earth).
Thanks,
David Schrunk
1:06 PM
First, the endless supply of sunlight will give rise to a variety of methods and mechanisms to harness this highly valuable source of energy from the Sun -- and mirrors in space will undoubtedly find many applications.
David Criswell has written about reflectors in Earth orbit for directing lunar-generated microwave energy to sites on the Earth (depicted in the Moonbook, Figure 6.1, page 89). Also, reflectors in space have been suggested for transmitting energy from one location on Earth to another.
I suspect that giant mirrors will be used for directing sunlight to desired locations on the Moon (lunar orbits are mostly unstable, but that can be overcome with solar sail navigation techniques) as you mentioned. In my Moonbook, we discussed solar sails (which are mirrors) for transportation; we also mentioned using them in stationary orbits above the north or south pole of a planetoid (such as Mercury and Mars) to serve as data relay points. The key to lunar base siting is power and direct communications with Earth (Malapert Mountain is optimum initial site in this respect). The key to lunar development is to begin with the first (limited capability) lunar base, THEN construct power / communication / transportation networks around the circumference of the Moon (polar region are preferred due to less construction effort and cost), THEN, by being connected into the continuously energized power, communication, and transportation grid, every location on the Moon will be available for exploration & settlement.
On the Moon, sunlight is desirable for power and solar oven applications, so I don't think we will be using solar umbrellas for shade in the near future. All equipment that does not absolutely need to be on the lunar surface will go underground because the underground environment is far less hazardous for every kind of equipment - same thing applies to people. Most of the work done on the Moon by humans will be underground or in structures that have tons of overhead regolith shielding.
Along that line, I foresee the use of 1000's (or millions) of giant sails in orbit around Venus -- their purpose would be to block sunlight and permit the atmosphere of Venus to cool to the point that life forms could exist. We could then bring in water from comets (and Jovian moons) and transform Venus into a livable planet... Someone should make a video about these ideas!
Having a transparent radiation umbrella on the Moon would be terrific -- no one wants to be a mole. Difficulty is that very thick glass (transparent) structures that mitigate radiation hazards and also provides a window to the universe may not be possible. My guess is that people will live in large (volumes on the order of 100-1000 cubic miles), very comfortable underground malls. By that time, technology should be advanced to the point that the ceiling of such structures could be made of TV screens that depict exactly what one would see if the protective dome were not there (including a real time, dynamic view of the Earth).
Thanks,
David Schrunk
1:06 PM
The reasons for going to the moon are varied and numerous. Not the least of which is the mining of regolith (moon dirt on the surface) for essential components such as Helium 3. Remember the lack of air on the moon allows for a mass driver (linear motor) to launch payloads of these products into space using only a long track and electricity.
But the long term prime real estate is in space, not on a planet. These lunar payloads can be used as raw material for space habitats which will afford its residents an opportunity for an unparralleled lifestyle, including earthlike gravity.
What do these people in space do for a living?
They are factory workers making stuff from the ingredients in lunar regolith. Even the leftovers become soil and solar storm radiation shielding for the giant habitats. This is no more a problem than putting a roof on your house here on earth to protect you from a rainstorm.
They are electrical workers, making giant solar cells to collect the sun's rays to make electricity and beam it to Earth via microwaves.
They are shopkeepers and service workers, plumbers and teachers, they are taxi drivers and gardeners. Very important those gardeners . . . they tend the greenery that refreshes the air!
I've had this image since the 70s. Download it to your computer. Look at it occasionally and share it with others. This is what our goal should be.
http://1632.org/bernal.jpg
--Dan
I was a guest on C to C in January.
I have an enabling technology for coating the mirrors on the lunar surface:
THE FUTURE DEVELOPMENT OF ENERGETIC THIN-FILM PROCESSES FOR SPACED BASED DEPOSITIONS
Michael L. Fulton
Ion Beam Optics Inc.
2060 E. Ave de Los Arboles #D243
Thousand Oaks, CA 91362-1376
ABSTRACT
NASA’s Lunar-Mars proposal (January 14, 2004) plans to use the Moon as an outpost for future voyages to Mars and beyond. The ability to deposit high performance thin-film coatings in the vacuum of lunar-space will be extremely valuable for executing many aspects of this new mission. Space-based thin-film depositions will enable the future development of flexible large-area space antennae and fixed telescope mirrors for lunar-station observatories. Deployable solar-propulsion concentrator arrays, coated in space, will accelerate the feasibility of human flights to Mars. Energetic deposition processes will be required for the efficient use of space-based thin-film coating technology. Advances in Filtered Cathodic Arc (FCA) technology enables the design and development of a robust system that can be robotically operated for depositing uniform thin films on large area deployed flexible substrates. Metals, especially gold and silver, will play a significant role in the development of advanced large area space deployable optical mirrors. Energetic processes, such as FCA, have terrestrially produced high performance metal, diamond-like-carbon (DLC), and dielectric material coatings that are suitable for space applications.
KEY WORDS: Space/Spacecraft/Satellite; Coatings/Films; Processing/Fabrication Equipment
1. INTRODUCTION
Based on NASA’s recent Lunar-Mars proposal (January 14, 2004), the Moon will be used as a temporary rest stop for voyages to Mars and beyond. This new government initiative revitalizes some of the earlier work that was done on “Lightweight Deployable Technologies” for space power and exploration. During the development of “Solar Thermal Propulsion” concepts the use of large-area deployable reflectors and concentrators were required (1). However, one crucial challenge in the development of this technology is the inherent difficulty associated with maintaining the mechanical stability of thin-film coatings after the device deploys from an acute folded state. If the thin-film coating is applied post deployment, then the performance of the film would not be compromised by the environmental insults of an earth launch, or the severe degrading stresses produced by unfolding a large flexible structure.
Returning to the Moon provides NASA with new opportunities and challenges. The author proposes that the ability to deposit high performance thin-film coatings in the vacuum of lunar-space will be extremely valuable in executing this new mission. One immediate requirement for developing space-based thin-film deposition technology is the apparent need for the inhabitants of a lunar station to be protected by a thermally controlled structure and window coatings. Another exciting application for spaced-based thin-film deposition technology is the coating of large-area space telescope mirrors that could be installed on the dark side of the Moon. If the Hubble Telescope is indeed decommissioned, then an astronomical observatory on the surface of the Moon would be a tremendous asset. Once assembled, the large-area adaptive-optical reflectors can be coated with pure silver, for example, that will not be contaminated, nor degraded, as experienced with earth-based coating technology.
Energetic deposition processes will enable the efficient use of space-based thin-film coating technology. One of the most promising technologies for this application is Filtered Cathodic Arc Deposition (FCAD). More than a century ago Thomas Edison produced coatings using a vacuum arc in a “Process of Duplicating Phonograms” (2). Nevertheless, only in the last decade has arc technology penetrated commercial markets, particularly in the coating of machine tools with metal nitrides. Sanders et al published an excellent comprehensive review of the arc technology over decade ago (3). Arc Technology could play a vital role in the future production of high quality thin-films for space-based deposition applications.
Even though a small number of research institutes have investigated filtered cathodic arc deposition for several years, early research work concentrated on the unique material properties of thin-films deposited using this method. Historically, carbon has received most of the research attention while aluminum oxide (Al2O3) and other materials, like titanium nitride (TiN), have more recently undergone serious laboratory investigation. The earliest studies found that the Filtered Cathodic Arc Deposition (FCAD) thin-film properties were highly dependent on the ion energy (usually controlled by applying a substrate bias) (4). Additionally, it was found that these films were rendered less useful by the unacceptably high density of particles adhering to the deposited coating. These, so-called, “macro-particles” were generated simultaneously with the FCAD ions, and could not be removed completely by the early filtering system designs (5-6).
Filtering techniques were investigated and the resultant reduction in macro-particles enabled the deposition of coatings that could be used in a number of critical applications. The new filtering designs involved changing the angles of the duct bend, increasing the substrate-to-target distance, and improving the mechanical filters (7-8). One of the most notable recent commercial application for the FCAD technology is the coating of Gillette razor blades with Diamond-Like-Carbon (DLC) (9).
2. TERRESTIAL PROCESS TECHNOLOGY
Before discussing the space deposition technology, the terrestrial version of the Filtered Cathodic Arc (FCA) system is presented in this section. In the space environment it is envisaged that the FCA technology will be employed without the incorporation of the Ion Assisted Deposition (IAD) technology. The first generation space applications will probably involve simple metal films; however, as the future need grows for more advanced space coatings incorporation of other energetic technology may be required.
2.1 Ion-Assisted Filtered Cathodic Arc Deposition (IFCAD) System
By coupling Ion-Assisted-Deposition (IAD) with FCAD a significant advancement in the deposition of optical thin-films is under development. It is now commonly understood that IAD substantially improves thin-film properties when compared to conventional Physical Vapor Deposition (PVD) (10-11).
Figure 1: IFCAD System
The above figure schematically represents the terrestrial Ion-assisted Filtered Cathodic Arc Deposition (IFCAD) technology.
The “self-sustaining” arc, produced in the water-cooled cathode block by a conventional arc welding power-supply, vaporizes the target material generating high-energy ions, neutral atoms and particles. Gold (Au+), Silver (Ag+), Carbon (C+), Aluminum (Al3+), or other charged ions are ejected from a metal arc-target and magnetically steered out of the duct, while a mechanical “non-line-of-sight path” filter captures the undesired macro-particles and neutrals. As the ejected ions emerge from the duct, an oscillating electromagnetic field scans (or sweeps) the plasma-beam to provide a uniform deposition over the substrate area. Analogous to brush painting, the ion beam is swept side to side to uniformly coat the substrate. Simultaneously, a beam of gas ions, from an end-Hall ion source, impinges on the arriving arc-generated ions, resulting in dense, well-adhered, stable thin-films. Since the only heat generated by this process resides in the water-cooled cathode assembly (external to the chamber), the substrate remains close to room temperature during the thin-film deposition (12-13).
The Ion-Assisted Filtered Cathodic Arc Deposition (IFCAD) system consists of a cylindrical rotary deposition chamber, orientated horizontally, and two Filtered Cathodic Arc (FCA) sources. One FCA source is associated with an end-Hall gridless Ion-Assisted-Deposition (IAD) ion gun.
Figure 2: Photographs of Terrestrial IFCAD Chamber
2.2 Ion Assist Deposition (IAD) Technology
The gridless ion source that is incorporated into the FCA process emerged from the pioneering work during the 1960’s of the Soviet Union and NASA in the development of ion thrusters for space propulsion, the Kaufman gridded ion generating source was adaptively designed for thin-film depositions (14-16). Early work with a modified gridded ion source proved that lower voltages and higher beam currents were most suitable for Ion Assisted Deposition (IAD) applications (17).
Therefore, an end-Hall ion source, described by Kaufman et al, was built for Optical Coating Laboratory Inc. (OCLI) (18). The author had the privilege of being the first engineer to put this source into a production application. Specifically, there was a dramatic need to increase the durability of deposited Zinc Sulfide (ZnS) layers. There are two primary crystal states for ZnS, Wurtzite (hexagonal) and Zinc Blende (cubic). In conventional Physical Vapor Deposition (PVD) substrate temperature is the first order effect for determining the durability of the ZnS layer. With the application of this first end-Hall ion source a ZnS cubic close packing (Zinc Blende) thin-film microstructure was attained. Astonishingly, the revolutionary benefit of this process was that the obtained film performance appeared almost independent of the substrate temperature. This first end-Hall IAD film was an order of magnitude more durable than any conventionally deposited ZnS film produced at OCLI up to that time.
The author had the opportunity to design, develop, and produce the window coatings for the International Space Station (ISS). Due to the large substrate size (29 inches dia.) it was theorized that by placing two ion sources in the chamber a superior coating would result. However, a serious problem ensued. The two sources, in simultaneous operation, arced vigorously, creating destabilizing oscillations in the power supply feed-back control system. By reconfiguring the chamber and the attending process conditions only one ion source was eventually used to successfully complete the required Space Station Window coatings.
Concurrent with the advanced work on the International Space Station (ISS) window coatings an investigation using a new ion source technology was initiated. Motivated by the need for a higher conversion of gas to ions this source was evaluated in a chamber with a similar configuration to the original two ion source set-up used for the ISS window program. The benefits for a higher conversion of gas to ions in the IAD process go beyond the ostensible requirement of placing two ion sources in the same chamber. Developing ion sources that use less operating gas is very beneficial for manufacturing high performance thin-film coatings and will be very important for future space-based IAD technology.
Summarizing generally, it has been demonstrated that bombardment of a growing film with energetic ions enhances the performance of the thin-film properties for optical filter applications. Improved film adhesion is achieved by ionic bombardment of the substrate prior to film deposition. Densification of the film, deposited on either heated or unheated substrates, is achieved with IAD. Other film properties may be positively influenced by this technique, such as: residual stress modification; surface morphology modification (crystal orientation, smoothing, and grain size); enhanced optical performance (stable refractive indices and low-absorption); and durability (10-11).
2.3 Ion-Assisted Filtered Cathodic Arc Deposition (IFCAD)
IFCAD couples Ion-Assisted-Deposition (IAD) with Filtered Cathodic Arc technology to provide a versatile platform for depositing high performance coatings in advancement optical and electro-optical material applications. The IFCAD technology processes produce super hard advanced thin-film materials such as: Amorphous Diamond-Like-Carbon (A-DLC); Aluminum Oxide (Al2O3); Aluminum Nitride (AlN); Titanium Nitrite (TiN); Titanium Oxide (TiO2: Rutile); Indium Tin Oxide (ITO); and many others are now feasible. In addition, the IFCAD system is designed to have the ability to deposit A-DLC, amorphous Al2O3, and many other materials in multi-layer thin-film structures suitable for advanced optical applications. The film properties produced by IFCAD technology are superior to other processes at elevated deposition temperatures, for example: the A-DLC thin-films have a micro-hardness in excess of 50 GPa (Diamond = 100 GPa); and the amorphous Al2O3 films have a hardness in excess of 20 GPa (bulk sapphire is 35 GPa). The new IFCAD system is ultimately designed to be an enabling technology for many novel commercial, military, and space applications (12-13).
• Al2O3 clear film of high hardness
• Ta2O5 optical coating material (2.1n)
• TiO2 high index optical coating material (>2.6 n)
• AlN purple decorative film
• TiN hard reddish gold wear resistant film
• TiCN dark gray and hard wearing
• CrN dull gray with low coefficient of friction
• ZrN brass colored film with good corrosion resistance
• ITO transparent conductive thin-film
• C3N3 material exhibiting extreme hardness (potentially)
Figure 3: Some of the Advanced IFCAD Thin-Film Materials
2.4 Applications using Terrestrial Ion-Assisted Filtered Cathodic Arc Deposition
There is an enormous number of potential applications for IFCAD technology, including: EUV mirrors; room temperature transparent conductors; thin-film reflectors; MEMS devices; Rugate filters; telecommunication filters; field emission flat panel displays; UV microlithography; scratch resistant ophthalmic lens; protective and barrier coatings; plastic Fresnel lenses; air craft and automobile windows; spacecraft thermal blanket coatings; hydrophobic films; credit card magnetic heads and tape; architectural glass; web and in-line coatings on plastics.
EUV mirrors, as one example, are of particular interest to NASA for space-based astronomical instrumentation. Considerable work has been done in this area at Goddard Space Flight Center (GSFC) where multi-layer coatings with high reflectance in the spectral range of 50 to 121.6nm have been produced and measured (14). Amorphous Diamond-Like-Carbon (A-DLC) deposited by the FCAD technology has shown great promise in this application, measuring a reflection of about 40% at 74nm wavelength.
The following table represents a comparison of the Carbon films produced by difference deposition methods. It should be noted that the FCA technology produces a very hard film at very low deposition temperatures.
Property Nat. Diamond CVD DLC DLC (a:CH) FCA (t:aC)
Hardness GPa 100 80 - 100 10 - 50 70 - 100
Density g/cm3 3.5 3.2 – 3.4 1.7 – 2.2 3.0 – 3.3
Friction Coeff. 0.1 0.1 (polished) 0.1 0.1
Film Roughness N/A 3μm Optically Smooth Optically Smooth
Adhesion N/A Low Moderate High
Process T oC N/A >600 20 – 325 20 - 150
Structure Crystalline Sp3 Crystalline Sp3 Amorphous
mostly Sp2 Amorphous
mostly Sp3
Reactive Gas N/A Yes Yes None
Transform T oC N/A >600 250 – 350 >500
Figure 4: Table of diamond-like-carbon produced with IFCAD
4. RELATED SPACE WORK
4.1 Protective Space Coatings
Protective coatings are of prime interest for solar power concentrator arrays and ultra-light inflatable Fresnel lens solar concentrators (21). The author had the opportunity to work on Boeing’s program for developing concentrator arrays using silicone Fresnel lenses. Deep Space I, launched on October 24, 1998, used solar concentrator arrays that were based on the architecture developed earlier at The Boeing High Technology Center.
Since silicone degrades in the presence of UV in the space environment the Fresnel concentrator needs protection from this radiation in order to maintain the high efficiency of the lens for the lifetime of the mission. The Deep Space I mission uses silicone Fresnel lenses covered with a thin cerium doped glass to absorb the UV. However, it was demonstrated that silicone Fresnel lenses could be coated with a dielectric thin-film reflector to protect the lens from UV. The major advantage for using a thin-film coating substitute for the glass is significant payload weight savings (22). The thin-film UV blocking design developed by Boeing for the Photovoltaic Array Space Power (PASP) module was deposited directly onto the silicone Fresnel lenses. This concept was successfully tested in space (23).
Work done by the author this year, using a specially configured IAD process for this application, is yet to be published. Fresnel silicone lenses (DC93-500) have been successfully coated and tested for UV degradation. As of this publication of this paper the testing is not complete, but the preliminary results to date are excellent. After 1000 ESH (Equivalent Sun Hours) of VUV radiation exposure, the Fresnel lens exhibits negligible change in optical performance. This coated Fresnel lens has also been subjected to 200 thermal cycles (-170o C to +70o C) without any apparent lost of optical or mechanical performance. In the future, the use of concentrators for space power applications could offer a significant technical advantage over conventional flat panel arrays. The coating developed for UV protection of Fresnel silicone lenses could also be applied after deployment in space on other UV radiation sensitive surfaces.
Figure 5: Measured spectrum of silicone (DC93-500) Fresnel lens, providing UV blocking and high transmission
4.2 Thermal Control
Thermal blanket coatings have been used from the beginning of the space program to protect the space vehicle from UV and IR radiation. The author had the opportunity to participate on the Boeing team which investigated the results from the Long Duration Exposure Facility (LDEF). LDEF was a satellite that spent 69 months in space to test a huge assortment of materials and coatings for space applications (24).
Kapton, and silicone were two of many materials exposed to Atomic Oxygen (AO) and UV radiation for the duration of the flight. Coated and uncoated Kapton and silicone samples were evaluated and compared for relative degradation after exposure to the high fluence of UV radiation and AO on the prolonged LDEF space flight. The study was comprehensive, involving a number of research groups examining hundreds of samples, resulting in a voluminous set of documents. Future space-based depositions will play a significant role in thermal control coatings.
5. FCA COATING TECHNOLOGY FOR SPACE APPLICATIONS
5.1 Space Deposition System (Pictures)
5.2 Space Antennas
L’Garde Corporation has specialized in the design and deployment of large-area space structures for solar propulsion and antennas (20). In the May 1996 the inflatable antennae experiment (IAE) was launched on Shuttle Mission 77. Antennae reflectors have a stowed volume of the inflatable device that is about one tenth of the deployed structure. This pioneering experiment has opened the way for the development of this technology for a number of applications (25). Thin-film coatings will be required for most of the following future envisaged applications of inflatable structures:
• Sunshades for space telescopes
• Deployment and support for solar arrays
• Planetary rovers
• Pressurized habitats in space or on planetary surfaces
• Extremely light weight solar sails, exploiting photon pressure
• Balloons to operate in planetary atmospheres
• Antenna reflectors
• Solar concentrators
• Precision booms
• Optical telescope mirrors
5.3 Space Solar Propulsion
Thin-film reflectors are of particular interest to the solar space propulsion effort, sponsored primarily by the Air Force and NASA. This technology relies on using large area coated polymer structures to reflect and focus concentrated solar energy to a space thruster. The solar thermal thruster is a high performance space vehicle suitable for transferring payloads from low earth orbit (LEO) to geosynchronous orbits (GEO). One vehicle design plans to use large inflatable parabolic concentrators to focus sunlight onto a high temperature absorber (26). This concept would be insured a greater success if the coating was deposited on the reflector after it is deployed.
5.4 Solar Power via Moon
By the year 2050 three to five times more energy will be required provide a prosperous life system for the human population of earth. However, the current means of energy production will be unable to meet this need without substantial negative consequences such as pollution, safety, reliability of supply, and cost. One innovative solution to this problem is collect solar energy on the surface of the moon, convert it to microwave energy and beam it back to the earth to supply electric power to augment other energy production methods (27). Without dwelling on the details of this proposal, suffice it to say that the need for depositing highly reflective coatings on the deployed optical concentrators will be required.
5.5 Solar Power from Space
Solar power from space has been proposed from nearly the beginning of man space flight. In this scheme solar collectors are placed in geosynchronous orbit and the solar energy is converted into a microwave beam that transports the energy back to a receiving station on the earth (28). Generating electrical power by collecting solar energy and beaming it back to the earth is fraught with economic and technical problems. However, with the use of thin-film space-based deposition technology will be an enabling step in the development of either the solar power from the moon or earth orbiting satellites.
5.6 Lunar Astronomical Observation
The establishment of a lunar base will be critical for the providing support for the future human flights to Mars. One of the ancillary benefits to having a lunar base is the ability to set up an astronomical observation facility. It is envisaged that very large-area reflectors, using adaptive optical systems, can be assembled on the lunar landscape. In order to maximize the unobstructed view (from earth’s shine) this could be built on the dark-side of the moon. Also, extremely powerful earth observations could be accomplished from setting up an observatory on the surface of the moon.
The lunar environment is particularly favorable for space-based depositions of large-area reflectors for telescopes. Lunar vacuum is on the order of 5.0 X 10-13 Torr. The typical vacuum required to deposit thin-films in a terrestrial chamber is in the 10-6 Torr range—seven orders of magnitude less favorable than the lunar surface. In Low Earth Orbit (LEO) metal film depositions would be compromised by oxidation. The LEO atomic oxygen fluence is on the order of 2.3 X 1020 atoms/cm2. Therefore, on the lunar surface pure silver, for example, could be deposited on the telescope mirrors with out being contaminated, corroded, nor degraded as observed in coatings produced by earth-based technology (29).
6. CONCLUSION
Since space-based deposition technology is not encumbered by a vacuum chamber, then other factors like power consumption, control, efficiency, and reliability must be considered. Filtered Cathodic Arc Deposition (FCAD) has the potential to satisfy theses requirements. The FCAD power is supplied by an arc welding transformer—this power supply would serve the dual function of a conventional arc welder for the lunar station. Simplicity is the central attribute of the FCAD technology; therefore, the source can be mounted on a robotic arm and the beam of deposition ions are applied to the substrate in a “paint brush” manner using laser guided controls to insure coating uniformity.
Space exploration and even colonization appears on the horizon and Filtered Cathodic Arc Deposition technology could play an important role in facilitating this endeavor by providing robotically deposited coatings over enormous space deployed structures for solar power and radiation protection. Spaced-based deposition of advanced materials could open a whole new era in astronomical observation, including large area telescopes on the surface of the moon.
As work progresses with these and other energetic deposition processes, it is the fervent hope of the author that scientists and engineers continuously seek imaginatively beneficial ways to apply their inventions and technology.
7. ACKNOWLEGEMENTS
A special thanks to Joyce A. Dever, NASA Glenn, for encouraging the presentation of my work for the SAMPE conference. The following companies have provided assistance and support for this work: Entech Inc.; L’Garde; Surface Optics Inc.; Thin Film Technology; and ZC&R Inc.
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Sorry to burst your bubbie, but if we went to the moon and imported 13 trillion watts of power to the earth, it would cause the greatest global warming ever, and literally fry us.
Simple math:
1) The earth right now receives 75 trllion watts of power from the sun.
2) Adding 13 trllion watts of imported power would increase energy to the planet 17%.
3) This would be equivelnt to moving the earth orbit 13% closer to the sun, which would surely fry us all.
The ONLY solution is wind power or earth solar, of these earth solar is the best.
We should just mass produce solar cells and wind turbines and cover the reletively small amount of land neded for them and be done with it.
We should also change building and architect codes to provide and require local energy systems. For example, we should design a DC current power system for use inside the home, complete with special outlet plugs for DC appliances.
Sorry to burst your bubbie, but if we went to the moon and imported 13 trillion watts of power to the earth, it would cause the greatest global warming ever, and literally fry us.
Simple math:
1) The earth right now receives 75 trllion watts of power from the sun.
2) Adding 13 trllion watts of imported power would increase energy to the planet 17%.
3) This would be equivelnt to moving the earth orbit 13% closer to the sun, which would surely fry us all.
The ONLY solution is wind power or earth solar, of these earth solar is the best.
We should just mass produce solar cells and wind turbines and cover the reletively small amount of land neded for them and be done with it.
We should also change building and architect codes to provide and require local energy systems. For example, we should design a DC current power system for use inside the home, complete with special outlet plugs for DC appliances.
P.S. The carbon nanotube sounds interesting. It might be that you can run it up to the ionosphere, and pull an electric current out to ground. That could possibly give a lot of power. It could also tend to cause stabilized weather patterns.
Hello NASA, we have another little problem!!!!
Maybe a lot of you young folks don't remember or weren't around at the time, but the Apollo Missions were a real thrill.
Personally I was corresponding with NASA, as I had speculated on the possibility that the moon could affect accelerated growth, whereby I envisioned lunar materials providing a huge benefit to agriculture.
But, although it turned out that the lunar materials did in fact affect accelerated growth they also had a down side. The lunar materials also affected genetic deformities and cancerous growths.
At the time, no one could understand why this was occurring, as there was no radioactivity involved other than what was considered normal background levels.
NASA was kind enough to forward pictures and text to me on the tests run on two plant species, beans and corn.
The lunar material was pulverized to a fine powder and placed in solution with water. This solution was poured onto the soil in which bean and corn seed had been planeted.
Both species grew at a fantastic rate, but produced severely deformed bean and corn plants with cancerous growths of a substantial size.
As no one knew what to make of this I felt very strongly that this was an opportunity to discover something new, so I worked on the problem on and off for sevcral decades.
Eventually I had it figured out, as it was due to a non-uniform relationship between the Earth and the moon that was causing the problem.
In effect the underlying dynamics of the lunar material was distorting the uniform continuance of field associated with the cellular structure of both the corn and beans.
Why I had originally suggested that the lunar material could cause accelerated growth was due to my having determined that the underlying dynamics of the moon were determined of the basis of a high energy potential, which was substantially higher than that of our planet Earth. But I had not considered the possibility that a non-uniform relationship might exist.
After further study I realized that not only was this non-uniformity factor a possibility but that it was merely an aspect of any relative relationship involving differences in time field frequencies, as the different fields of frequency accelerate at different rates.
All of which is very interesting, but what does it mean?
The bottom line is simple, we lack a general understanding and anything close to the technology required to uniformly access another planetary body, be it a moon, planet or star etc.
So what we are faced with is a brick wall, in terms of our ability to safely access the resources of space.
In recent years I wrote to the Canadian Space Agency informing them of my willingness to share my work with them, as I felt this gave them a significant bargaining chip in their dealings with NASA.
There response informed me that they had carefully checked my information out and had found that no such test results occurred in relation to the lunar material returned during the Apollo Missions.
I was dumbfounded, how could this be possible? But on checking directly with NASA I soon discovered that the original test results had been significantly altered to reflect a uniform relationship existing between the Earth and the moon.
Now we want to go back and build a moon base, as was originally planned decades ago.
Wait a minute, we have a very serious problem here and any attempt to establish a permanent manned base on the moon is going to put the health and safety of the lunar crew in serious danger.
On top of this NASA is talking about utilizing Martian water for a manned mission to Mars. Anyone who drinks that water, regardless of it's apparent purity, is going to become very ill, which would represent a clear and present danger to the mission crew.
Obviously there are many people still around who remember the various plant and animal species subjected to the lunar material and undoubtedly they remember the structural alterations and ill effects, which NASA now denies occurred.
Of course this problem should have put the whole idea of manned missions in question, which it obviously did, as there have been no manned missions to the moon or any other planetary body since.
But now it's suddenly okay, I don't think so.
Hard scientific data was sensored and ultimately fudged to reflect a clear to go in relation to further developments, which were in fact a waste of money. To the point where we are now floundering around trying to make something look good.
We have people claiming the moon landing was faked, which simply muddies the water.
There is no possible way that the original lunar tests could have been faked, no way.
But they were fudged, as anyone can see from taking a look at the NASA archives. It states very clearly that the lunar materials caused no structural alterations or ill effects to the various plant and animal species tested.
But that the lunar material did affect accelerated growth in plants, which suggests that lunar material could be of benefit to terestrial farmers.
Come on, who are you trying to kid with this stuff.
Now we come to the idea of placing solar panels on the moon and beaming the power down to Earth.
Whoa boy, we are talking non-uniform potentials here, which is nothing to play around with. You do what I think you want do and you are going to have problems you wouldn't imagine even in your worst nightmares.
We already have tidal influences corresponding to the non-uniformity existing between the Earth and the sun and the Earth and the moon.
You start playing with electrical discharges originating from the moon and you'll wish you were somewhere else.
Earth orbit and the moon are two completely different situations, it's like trying to compare roast beef and plum jam. It's the old apples and oranges thing.
If you want more on this go to my blog, which is Gravity Control Idealism linked to gravitycontrol.org
Someone or a group of people have deliberately altered the lunar test results. Aside from causing all of us a lot of headaches, it has also resulted in a lot of time and money being wasted for nothing.
Back in the late 60's and early 70's this was all widely publisized, so how did it get altered? But it did get altered.
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