Reduced startup costs can open up new space activities such as spacecraft manufacture and assembly. (Source: NASA)
by Jeff Greenblatt and Al Anzaldua
Monday, July 29, 2019
<img src = "http://s7.addthis.com/static/btn/v2/lg-share -en.gif "width =" 125 "height =" 16 "alt =" Bookmark and Share and Potential Benefits of Space-based Abilities for Life on Earth from an Environmental, Social and Economic Perspective, Including:
- Space activities that have a positive effect today (eg Earth observation for weather and climate)
- Space activities that could have a positive impact in the next 5 to 20 years (eg mega-constellations of communications satellites)
- Space activities This could have a positive impact in the longer term (eg widespread space production and industrialization).
In the following, we describe nearly 30 types of activities, which can either bring significant benefits now or have a positive impact in the coming decades.
The world is already profiting greatly from space technology, particularly in terms of communications, location services, earth observation, and economic activities associated with state-funded space programs. Mankind's space capabilities have increased significantly since Sputnik's launch in 1
|Low start-up costs will continue to dramatically change the economics of many space business models, enabling a new era of capabilities once thought unaffordable.|
One reason for this recent explosion of space related activities is the sinking launch cost of low Earth orbit (LEO). In the past, the introduction of LEO was one of the most expensive elements in space travel. In the past, the average cost was more than $ 10,000 per kilogram of takeoff mass. Recently, however, space companies such as SpaceX, Blue Origin, and United Launch Alliance (ULA) have successfully introduced reusable launcher technology, which promises to significantly lower launch costs for LEO. SpaceX's Falcon Heavy has the industry's lowest cost, with a base price of $ 1,655 per kilogram for LEO.  The long-term ambitions of SpaceX and many other companies are to reduce these costs to $ 100 per kilogram or less.  Such low startup costs will continue to dramatically change the economics of many space business models, opening a new era of abilities once considered prohibitive.
Other technologies, such as producing materials from the Moon, Mars, or asteroids in space, could further enhance the economics of space activities by drastically reducing the amount and cost of Earth-fired material. A good example is the procurement of rocket fuels from deep-water lunar regions or asteroids in space, which could reduce transport costs to locations outside LEO.
Space Activities with Positive Impact Today
1. Earth Observation on Weather Forecasting and Climate Observation: Accurate weather forecasting made possible by space systems has become an important element in our daily lives, affecting government , Industry and personal decisions. Satellites used for weather forecasting almost certainly save thousands of lives each year by warning the public about storms. Although no one can tell exactly how many lives are saved each year, it should be noted that in 1900 a hurricane in Galveston, Texas killed 6,000 to 12,000 people because they had no warning. Earth observation satellites also monitor greenhouse gases and other important climate indicators as well as the overall health of the Earth's ecosystem. Without this kind of environmental information from satellites, plans to tackle climate change would have less scientific basis.
2. Earth Observation: Earth Observation provides information and support for agricultural production, fisheries management, freshwater management and forestry, and monitoring of harmful activities such as illegal logging, livestock, fires and polluting mining.
3. Space-based Communication Services: Space communication capabilities have a positive effect on almost every aspect of human civilization. Satellite technologies have already revolutionized banking, finance, navigation and day-to-day communications, making international and national long distance calls, video feeds, streaming media and satellite TV and radio routine. (See point 1 in the next subheading, where we are heading in this area.)
4. Spaceborne Positioning, Navigation and Timing (PNT) Services: Global PNT satellite systems, which can accurately locate a location on the Earth's surface within a few meters (or much better), have and seafaring improved. Logistics (including passenger services), precision farming, military operations, power grids and many other industrial and social aspects of life on earth. Mobile-based space-based location services used by applications on mobile phones, from maps to dating services, are so heavily integrated into modern life that their sudden onset is viewed as catastrophic.
5. Increasing Economic Opportunities in Commercial and Non-Space Sector Expansion: Apart from the long-standing commercial satellite services, our expanding space industry is bringing along the process of overcoming the exclusive dependence on limited government budgets and cost surcharges offers economic opportunities, not only for those working directly in the space sector, but also for non-space operators, including many small businesses. In other words, an expanding commercial space industry will not only create high-tech jobs, but also everyday jobs in construction, catering, wholesale, retail, finance and more in the communities where commercial space companies operate.
6. Inspiration for STEAM Training: Beyond the economy, a healthy space sector will continue to inspire young and old people for new frontiers, discoveries, and technologies, and interest in STEAM disciplines (natural sciences, This contributes to the creation of a science-based society capable of participating in an increasingly technology-driven world.
7th International Space Cooperation Against Geopolitical Tensions: Joint space projects between nations are sometimes the only positive force counteracting mutual distrust and geopolitical rivalries. The ISS is a prime example of such a project, to which all participating nations are proud. Cross-border business-to-business relationships also serve the same purpose. We are a global community, and the public and private space efforts make us interdependent and connected.
|Offering people the opportunity to experience the overview effect at first hand can lead to major changes in attitudes toward the environment and social well-being, and become a major "side effect" of a growing space tourism industry.|
8. Outer Earth Spalling: Since the beginning of the space program, there have been more than 2,000 examples of space-developed technologies that have since found useful applications on Earth, including cordless power tools, freeze-dried Food and fire retardant fire-fighting equipment, integrated circuit, light insulation, kidney dialysis improvements, flash detection and automated credit card transactions. Each year, NASA spins out spin-offs across a broad range of topics covering transportation, public safety, consumer goods, energy and environment, information technology, industrial productivity, and health and medicine. Future health-related spin-offs are expected to result from addressing the medical issues of isolated populations in outer space.
Space Activities with Potential for Positive Impact over the Next 5 to 20 Years
1. Megaconstellations : This is an emerging business with great potential that could potentially increase the efficiency, capacity and safety of a variety of services for earthbound business customers by dramatically reducing communication latency while increasing throughput and global coverage. Data satellite constellations, most of which are scheduled to launch for LEO, will benefit end-users of banking, maritime, energy, Internet, mobile and government services. A related aspect of this service business is focused on everyday Internet end users and will provide high-speed and bandwidth global coverage that benefits billions of people. Thousands of LEO satellites are planned by SpaceX, OneWeb, Telesat, Amazon, Samsung and others. However, such constellations require orbit mitigation and remediation services, as discussed below.
2. Space production of hard-to-produce materials on Earth: There are currently only a few materials that can only be produced in the weightlessness of space and that have a sufficient value on Earth for their production as well to justify at today's high startup costs. The hallmark is ZBLAN, a fiberglass material that can result in significantly lower signal losses per fiber length than anything that can be produced on Earth. This material is being experimentally manufactured by Made In Space, Inc. on the ISS with two competitors working on similar products. Other on-orbit fabrication projects at ISS include biodynamics, industrial crystallization, superalloy casting, human stem cell growth, and ceramic stereolithography. 
3. Fast Suborbital Point-to-Point Transport: Supersonic air transport dates back to the Concorde in the 1970s. More recently, several companies have begun exploring technologies for even faster transportation with so-called "hypersonic" aircraft. SpaceX has announced that it will use its currently under development Starship / Super Heavy missile system to skip these companies and carry out a point-to-point (P2P) suborbital journey that temporarily leaves the Earth's atmosphere shortly thereafter another place to reenter the planet. The potential savings in travel time with this technology are enormous, allowing access to all parts of the world in less than an hour. While current technologies continue to rely on fossil fuels as blowing agents, it is possible to replace them with hydrogen / oxygen blowing agents that are electrolyzed from water. Such technology would not emit carbon dioxide and could thus be a "green" alternative to long-haul flights, while significantly reducing travel times.
4. Space Tourism: There are now several start-up companies whose sole purpose is to provide cost-effective access to the edge of space. Some use suborbital rocket technology, which allows some minutes of weightlessness at a height of about 100 kilometers above the surface, while others use high altitude balloons to make access to high altitudes more cost effective without becoming weightless. The desire among ordinary people to travel into space is strong. A recent survey found that more than 60 percent of Americans would do so if they could afford a ticket.  Space tourism, including hotels encircling earth and moon, sports arenas, yacht cruises, and the like, could soon be open to millions of people with declining access costs to space.
5. The Summary Effect: A well-known phenomenon experienced by virtually every human being who has traveled to space and looked back on our world from above is the "overview effect,"  of which is normal Unity and concern for the fragility of our planet are described as a sudden but lasting feeling of the human being.  Allowing people the opportunity to experience first-hand the overview effect can lead to major changes in attitudes towards the environment and social well-being, and become a major "side effect" of a growing space tourism industry.
6. Asteroid Prevention: With increasing knowledge of the space environment, humanity has become aware that asteroids that may cause great damage sporadically invade the Earth's atmosphere and reach the surface. Although an early warning system is an obvious first response to this threat (though this feature is far from operational), some asteroids can pose such a deadly threat that a distraction is the only way to make a devastating loss of life on Earth avoid. Several technologies have been studied to accomplish this task, but the capability is still in its infancy. A side effect of investing in such a capability is that the more we learn about such "deadly" asteroids, the better we can identify valuable asteroid asteroid degradation products.
7. Space Solar Energy: In space, sunlight is not filtered by the Earth's atmosphere, and in orbits of sufficiently high altitude, sunlight can shine more than 99 percent of the year.  The principle of space sun energy (SSP) is to capture this abundant sunlight and then radiate it to the earth's surface after conversion to microwaves or laser light, where ground-based receivers convert the energy into electricity.
Such a system can power much of the day. In addition, due to its position in space, the energy can be radiated to virtually any location on Earth within sight of the satellite and instantaneously directed to locations thousands of miles apart, or even to multiple locations simultaneously through the use of phased array -Technology. An early application could focus on the power supply of isolated communities or on disaster relief.
|It is possible that space-based data centers will ultimately become more cost effective, resulting in lower power consumption and lower CO2 emissions on Earth.|
By reducing the cost of deploying and mass-producing SSP modules, SSP can potentially become cheaper than wind or solar power today, a few cents per kilowatt-hour. ] With maturity, and especially with the beginning of mass production of units in modular SSP systems from in-situ space resources, it will be able to replace much of the base load power as well as peak power generation as the power is sent everywhere it can be requested on request. In addition, the provision of base load power through SSP will reduce the need for energy storage by batteries or other systems that could negatively impact the environment.
8. Space-based Data Centers: Along with the communications network itself, data centers are at the heart of the Internet, which drives much of today's economy, but consume more and more power. Nowadays, data centers are often in cold climates to take advantage of lower operating temperatures and cooling loads, and for similar reasons, there have been serious discussions about placing data centers underwater.
Another option could be to place servers and their power supply directly in space using virtually unlimited solar energy (see previous discussion on SSP) to reduce the burden of earth-based electricity systems on their power supply. While cooling can be more demanding (the vacuum in space is a very good thermal insulator), there are several benefits including increased physical safety, reduced signal transfer times, and superior performance of rotating disk drives in microgravity. Space-based data centers may ultimately become more cost-efficient, resulting in lower power requirements and lower CO2 emissions on Earth.
9. Space depletion of high quality elements: The focus of most space depletion companies today is on water, which delivers rocket fuel in orbit and thus contributes to reducing the cost of space operations. Other abundant materials such as iron and other metals will be valuable for space construction and avoid the cost of starting structures from the earth. However, space depletion could eventually mature to the extent that other valuable elements could be obtained as a natural by-product of large volumes of processed material, justifying the high cost of manufacturing in space. Prime examples are the platinum group metals (platinum, palladium, rhodium, rhenium, osmium and iridium, together referred to as PGM) and gold, which today can achieve prices of $ 30,000 or more per kilogram. It is possible that some other elements, such as For example, "critical materials" listed by the US Department of Energy could reach a similar price level over the next two decades and become accessible to space depletion. Delivering large quantities of space-based material can be cost-effective if it is returned by using space-produced ablative heat shields that can be obtained by controlled landings in shallow water. The space depletion techniques are also different from the water-based approaches commonly used on Earth and would instead rely primarily on thermal separation and multi-stage processes to aggregate small amounts of metal, typically found in terrestrial ores, into ever higher concentrations. For example, some asteroids may contain high concentrations of high grade metals that are suitable for mechanical separation.
10. Closed Circuit Ecosystems, Material Recycling and In-situ Resource Use: Limited physical resources and the inherently high costs of operating in space naturally lead to the efficient use and recycling of gases, Water, nutrients and other materials for life support and other purposes. Efficient reuse and / or recycling of plastics, aluminum, steel and other structural materials also offers great benefits. Once these systems have matured for space applications, the potential for using these technology solutions on Earth is enormous, saving energy and material resources and shifting people's perspective from one-off to circular economic thinking. In addition, there is a need for large-scale space operations that rely as much as possible on in-situ resources and literally use the rocks and regoliths around which the missiles land as raw materials for construction, life support, and other needs. If such processes can be developed with a high degree of efficiency and reliability in space, there is also the potential to adapt them for use on earth for construction and processing goods.
11. Intensive Organic Cultivation Techniques: With increasing numbers of crewmembers in space, and in particular with the construction of bases on distant worlds such as Mars, it will be impractical to feed these populations with imported food. This requires the development of high-density, water-efficient, energy-efficient and fully organic farming methods operating in a closed loop. It is to be expected that such techniques are widely used on earth to increase food production.
12. Science projects and programs that can only be performed in space (or even better): In addition to the science and technology projects and programs listed above, there are others that are only conducted in outer space can. For example, the Earth's atmosphere filters out some wavelengths of light so that telescopes that want to observe in those bands can only be placed in outer space. The moon shore is protected from the moon by electromagnetic emissions from the earth. For this reason, with reasonable care and infrastructure, it is an ideal place to monitor low-frequency radio waves from space. Many other types of telescopes benefit from being outside the Earth's atmosphere. Freed from the gravity of the earth, extremely large structures could be assembled in the orbit, z. Modular arrays for radio and optical interferometry telescopes and other types of receivers or transmitters. Finally, risky biological experiments could be carried out in isolated laboratories in space or on the moon to protect the earth's population with a huge harsh vacuum.
13. Orbital Debris Management : Although this is not a technology of direct use to the Earth, the removal of debris from spent rocket stages, faulty satellites, and all other types of space debris into orbits places one is an increasing threat to space operations and must eventually be dealt with. The worst scenario is that a series of accidental or intentional collisions in orbit lead to an exponential increase in debris, resulting in an inability to operate in space – the so-called "Kessler syndrome". To solve this problem, technologies are being studied in different ways, but it is currently very expensive. With lower start-up costs and space infrastructure investments, it may be possible to cost-effectively manage debris (at least one company, Cislunar Industries, plans to melt debris from orbit and refine useful materials for use in space.) Another company, Star Technology and Research Corporation is developing a non-fuel-consuming electrodynamic soil eliminator (EDDE), which may also be useful for monitoring debris in orbit.
Space activities with potential for positive effects in the distant future
1. Widespread space production and industrialization: Finally, the falling costs of space-based manufacturing and the rising cost of earth-based production (due to increasing scarcity, environmental impacts) , Labor standards, etc.) have many causes, if not Virtually all extractive industries and their downstream manufacturing processes are moving into space. The impact of such a change would be serious, as the side effects of these activities would be shifted to locations in space that would not adversely affect biological ecosystems, endangered species or human populations. The much larger area of space would provide virtually unlimited space, energy and materials for operation. Provided that such industrial activities are carried out responsibly so as not to pollute or otherwise adversely affect the ability of future generations to use space resources (an example of which is described above under Orbital debris removal), this could be crucial to the permanent conservation and restoration of the health of the earth.
|Provided that such industrial activities are carried out responsibly so as not to pollute or otherwise impair the ability of future generations to use space resources, this could be vital for the long term preservation and restoration of Earth's health his.|
2. Waste Disposal in Space: As the space launch becomes more reliable, it will be possible to dispose of toxic substances outside the Earth. For example, in about a century, the launch of space should be highly reliable and allow nuclear waste to be disposed of orbitally without future generations having access to it to mine valuable materials. Storage of nuclear waste on Earth for hundreds of years is a much simpler problem than the current much greater challenge of storing it over tens of thousands of years. This change of perspective could make the clean-up of nuclear waste much easier.
3. Building a space-based "sunscreen" to reduce global warming: The severity of climate change may require radical approaches, such as reducing sunlight on the earth's surface in conjunction with greatly reduced greenhouse gas emissions. Known in the climate cycle as "solar geoengineering" or "solar radiation management" (SRM), most approaches are based on the injection of aerosol particles in the stratosphere, others increase the cloud reflection or directly block the sunlight in space. First proposed three decades ago, the  concept of bringing a fleet of spacecraft into orbit to reduce incident solar radiation and lower surface temperatures has received increasing attention following Roger Angel's publication of influential paper in 2006.  The introduction of asteroid dust with similar effects into the Earth orbit has also been investigated.  While no identified SRM method can perfectly neutralize the effects of climate change (and can not stop ocean acidification), SRM may be the only way to rapidly lower global temperatures. The benefits of space-based approaches include the absence of unwanted chemical interactions in the Earth's atmosphere and the ability to be switched off quickly when unforeseen consequences are detected. Launching trillions of tiny spacecraft to create a huge "sunscreen" over the planet is no longer possible today, but could be possible with lower start-up costs, the development of ultralight awning materials, and mass production of spacecraft.
4. Physical Benefits of Low Gravity: Although currently very speculative, a number of physical illnesses that could be aggravated by Earth's gravity (including obesity, joint pain, and osteoporosis), may result in low gravity teilweise oder vollständig beseitigt werden Umweltbedingungen wie Mond, Mars oder künstliche Schwerkraft (rotierender Lebensraum) in der Erdumlaufbahn. Niedrige Schwerkraft ist von der Schwerelosigkeit (technisch gesehen „Mikrogravitation“) zu unterscheiden, wie sie an Bord der ISS zu finden ist und die nachweislich fast überall negative Auswirkungen auf die Gesundheit hat. Die Forschung auf diesem Gebiet steckt noch in den Kinderschuhen, da für künstliche Gravitationszentrifugen im Orbit fast keine Mittel zur Untersuchung dieser Wirkungen beim Menschen zur Verfügung stehen. Wenn eine Finanzierung zustande kommt und positive Ergebnisse erzielt werden, könnte es äußerst wünschenswert sein, Zeit in geringer Schwerkraft zu verbringen, um eine beträchtliche Anzahl von Menschen dazu zu bewegen, den Weltraum zu besuchen oder sogar dort zu leben.
5. Nahrungsmittelproduktion im Weltraum für Menschen auf der Erde: Sobald die Weltraumtechnologie so weit fortgeschritten ist, dass sich Millionen von Menschen im Weltraum selbst versorgen können, könnten die weitaus größeren Ressourcen des Weltraums für den Anbau von Nahrungsmitteln für Menschen auf der Erde genutzt werden Gut. In der Tat könnte die derzeitige Spannung zwischen der Nutzung des Bodens für die menschliche Besiedlung, die Landwirtschaft, die industriellen Tätigkeiten und den Naturschutz unterbrochen werden, wodurch genügend Raum für all diese konkurrierenden Bedürfnisse geschaffen wird. Anfänglich würden nur kleine Mengen an Nahrungsmitteln oder Spezialgegenständen, die als zu teuer erachtet werden oder die die Ökosysteme der Erde belasten, zur Erde transportiert, aber schließlich könnten große Teile der Welt aus dem Weltraum gespeist werden.
6. Migration der menschlichen Bevölkerung in den Weltraum: Einer der Haupttreiber der Weltraumentwicklung ist die Schaffung neuer Orte, an denen Menschen leben, arbeiten und erforschen können. Während derzeit nur sehr wenige Menschen in der Lage sind, den Weltraum zu besuchen, ist die Weltraumgemeinschaft heute auf einem klaren Weg, eine kommerzielle Weltraumtourismusbranche aufzubauen und kleine, aber permanente menschliche Stützpunkte auf dem Mond und dem Mars zu errichten. Sehr große Weltraumhotels ähneln kleinen Weltraumsiedlungen in Äquatorial-LEO (in Erdnähe und in Äquatornähe), in denen die Strahlungswerte im Weltraumvergleich sehr niedrig sind. Der größte Unterschied könnte die Rotationsrate sein, da die Hotelgäste möglicherweise nur ein wenig Schwerkraft wünschen, um das Besteck an Ort und Stelle zu halten, wohingegen Siedlungen die volle Schwerkraft der Erde wünschen, damit Kinder stark aufwachsen. Solche kleinen Lebensräume können zu sehr großen Weltraumsiedlungen führen (z. B. "O'Neill-Zylinder"), die mit Weltraumressourcen ausgestattet sind, die jeweils Millionen von Menschen beherbergen können. Letztendlich könnten solche Siedlungen es der menschlichen Bevölkerung ermöglichen, zu wachsen, um die viel größere Region des Sonnensystems zu füllen, wodurch der Druck auf das begrenzte Land und die begrenzten Ressourcen der Erde verringert wird.
7. Möglichkeiten für soziales, wirtschaftliches und politisches Experimentieren: Da Weltraumsiedlungen physisch und ökologisch voneinander getrennt wären, besteht die Möglichkeit, neue Ideen auszuprobieren, ohne andere negativ zu beeinflussen. Darüber hinaus können solche Aktivitäten die einheimischen Kulturen nicht zerstören oder die lokalen Ökosysteme aus dem einfachen Grund schädigen, dass es keine gibt (mit einem entfernten Potenzial für mikrobielles Leben auf Mars, Europa, Enceladus oder möglicherweise an anderen Orten). Ungeachtet der Dezimierung der einheimischen Kulturen und Die Schrecken der Sklaverei und die Expansion der westlichen Kultur in die Neue Welt boten Gelegenheit, neue soziale, wirtschaftliche und politische Systeme zu errichten. Die Siedler der Neuen Welt haben nicht nur die Demokratie nach westlichem Vorbild weiterentwickelt, sondern auch lokale Ressourcen entdeckt, die sie in Form von Handelsgütern, die das wirtschaftliche, kulturelle und soziale Leben in Europa bereicherten, nach Europa zurückgebracht haben. Die weitverbreitete Migration von Menschen in Weltraumsiedlungen würde ähnliche Experimentiermöglichkeiten bieten und die kollektiven Frustrationen von Menschen auf der ganzen Welt nutzen, die sich nicht in der Lage fühlen, ihre kaputten Systeme zu ändern, ohne jedoch die einheimische Bevölkerung auszubeuten. Erfolg im Weltraumbereich würde wahrscheinlich im Laufe der Zeit zur Rückübertragung neuer Ansätze und Produkte auf die Erde führen, ohne dass die Gefahr einer Ausbeutung durch den Menschen besteht.
8. Untersuchung und Erhaltung von Ökosystemen im Weltraum: Die Rekonstruktion komplexer Ökosysteme im Weltraum könnte Gelegenheit bieten, unser Wissen zu verfeinern, um terrestrische Umgebungen besser zu schützen, und wertvolle Erfahrungen bei der Erhaltung solcher Ökosysteme für die Unterstützung des menschlichen Lebens im Weltraum liefern. In the long term, O'Neill cylinders could also be used to recreate Earth environments on a large scale, with the express purpose of preserving endangered species, or even regenerating previously extinct species with genetic technology. Such efforts may become some of the more powerful legacies of the Space Age: the preservation of biodiversity most affected by human expansion.
We believe that the benefits that humanity currently derives from Space, plus the vast anticipated future benefits described in this paper, overwhelmingly support the case for the continued exploration, development and settlement of Space.
An earlier version of this paper appears on the National Space Society website. The authors also gratefully acknowledge the contribution of Jason Aspiotis to the first draft of our paper and David Cheuvront to later drafts.
- Little public information has been disclosed on Falcon Heavy prices, but on February 12, 2018, Elon Musk posted on Twitter a reusable price of $95 million for 90% of expendable capacity to LEO. Based on an expendable capacity of 63,800 kilograms posted on the SpaceX website in July 2019, this makes for a base price of $1,655/kilogram.
- Elon Musk estimated in 2017 that the cost of sending a payload to Mars would be less than $140/kilogram. Using his estimates, sending this payload to LEO would cost $103/kilogram (https://doi.org/10.1089/Space.2017.29009.emu).
- Comstock, D (2019). “Explore Humans in Space: LEO Economic Development Strategy Overview & Near Term Plans,” Presentation to the NASA Space Portal Commercial Space Zoom Meeting, 26 June.
- LEO Tourism Market Analysis (2020-2030) (in progress)/li>
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- Garan, R (2015). The Orbital Perspective: Lessons in Seeing the Big Picture from a Journey of 71 Million MilesOakland, CA: Berrett-Koehler Publishers, ISBN 978-1-62656-246-2.
- Mankins, JC (2014). The Case for Space Solar PowerHouston, TX: Virginia Edition Publishing, ISBN 978-0-9913370-1-9.
- See graphs on pages 26 – 30. Mankins, JC (2016). “New Developments in Space Solar Power,” 67th International Astronautical Congress, 26-30 September.
- Early, JT (1989). “The Space based solar shield to offset greenhouse effect,” J Br Interplanet Soc 42:567–569.
- Angel, R (2006). “Feasibility of cooling the Earth with a cloud of small Spacecraft near the inner Lagrange point (L1),” Proc Natl Acad Sci 103: 17184-17189.
- Bewick, R, JP Sanchez, CR McInnes (2012). “The feasibility of using an L1 positioned dust cloud as a method of Space-based geoengineering,” Adv Space Res 49: 1212–1228.
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