NationMaster - Encyclopedia: Solar sail

Solar sails (also called light sails or photon sails, especially when they use light sources other than the Sun) are a proposed form of spacecraft propulsion using large membrane mirrors. Radiation pressure is about 1e-5 Pa at Earth radii^[1] and decreases by the square of the distance from the light source (e.g. sun), but unlike rockets, solar sails require no reaction mass. Although the thrust is small, it continues as long as the light source shines and the sail is deployed. In theory a lightsail powered by an Earth-based laser can even be used to decelerate the spacecraft as it approaches its destination. Image File history File links Question_book-3. ... For other uses, see Light (disambiguation). ... Sol redirects here. ... A remote camera captures a close-up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is any method used to change the velocity of spacecraft and artificial satellites. ... Membrane mirrors are mirrors made of thin films of material, such as mylar. ... Radiation pressure is the pressure exerted upon any surface exposed to electromagnetic radiation. ... Working mass is a mass against which a system operates in order to produce acceleration. ...

Solar collectors, temperature-control panels and sun shades are occasionally used as expedient solar sails, to help ordinary spacecraft and satellites make minor corrections to their attitude and orbit without using fuel. This conserves fuel that would otherwise be used for maneuvering and attitude control. A few have even had small purpose-built solar sails for this use. For example, EADS Astrium built Eurostar E3000 geostationary communications satellites use solar sail panels attached to their solar cell arrays to off-load transverse angular momentum, thereby saving fuel (angular momentum is accumulated over time as the gyroscopic momentum wheels control the spacecraft's attitude - this excess momentum must be offloaded to protect the wheels from overspin). Some unmanned spacecraft (such as Mariner 10^[2]) have substantially extended their service lives with this practice. Aircraft attitude is used to mean two closely related aspects of the situation of an aircraft in flight. ... EADS Astrium, one of the three business units of EADS Space, this company being a subsidiary of EADS, is an European space manufacturer involved in the manufacture of spacecraft used for science, Earth observation and telecommunication, as well as the equipment and subsystems used therein and related ground systems. ... A geostationary orbit (abbreviated GEO) is a circular orbit in the Earths equatorial plane, any point on which revolves about the Earth in the same direction and with the same period as the Earths rotation. ... A solar cell, made from a monocrystalline silicon wafer A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. ... This gyroscope remains upright while spinning due to its angular momentum. ... Unmanned space missions are those using remote-controlled spacecraft. ... The Mariner 10 probe. ...

The science of solar sails is well-proven, but the technology to manage large solar sails is still undeveloped. Mission planners are not yet willing to risk multimillion dollar missions on unproven solar sail unfolding and steering mechanisms. This neglect has inspired some enthusiasts to attempt private development of the technology, such as the Cosmos 1. An artists rendering of Cosmos 1 orbiting the Earth. ...

The concept was first proposed by German astronomer Johannes Kepler in the seventeenth century. It was again proposed by Friedrich Zander in the late 1920s and gradually refined over the decades. Recent serious interest in lightsails began with an article by engineer and science fiction author Robert L. Forward in 1984. Kepler redirects here. ... Friedrich Zander (August 23, 1887 - March 28, 1933), often referred to as Fridrikh Tsander (transliterated from the Russian version of his name: Фридрих Артурович Цандер) or Fridrihs Canders (the Latvian version of it) was a Soviet pioneer of rocketry and spaceflight. ... Robert Lull Forward, commonly known as Robert L. Forward, (August 15, 1932 - September 21, 2002) was an American physicist and science fiction writer. ...

How they work

The spacecraft deploys a large membrane mirror which reflects light from the Sun or some other source. The radiation pressure on the mirror provides a minuscule amount of thrust by reflecting photons. Tilting the reflective sail at an angle from the Sun produces thrust at an angle normal to the sail. In most designs, steering would be done with auxiliary vanes, acting as small solar sails to change the attitude of the large solar sail (see the vanes on the illustration labeled Cosmos 1, below). The vanes would be adjusted by electric motors.^[3] Radiation pressure is the pressure exerted upon any surface exposed to electromagnetic radiation. ...

In theory a lightsail driven by a laser or other beam from Earth can be used to decelerate a spacecraft approaching a distant star or planet, by detaching part of the sail and using it to focus the beam on the forward-facing surface of the rest of the sail.^[4] In practice, however, most of the deceleration would happen while the two parts are at a great distance from each other, and that means that, to do that focusing, it would be necessary to give the detached part an accurate optical shape and orientation.

Sails orbit, and therefore do not need to hover or move directly toward or away from the sun. Almost all missions would use the sail to change orbit, rather than thrusting directly away from a planet or the sun. The sail is rotated slowly as the sail orbits around a planet so the thrust is in the direction of the orbital movement to move to a higher orbit or against it to move to a lower orbit. When an orbit is far enough away from a planet, the sail then begins similar maneuvers in orbit around the sun.^[5]

The best sort of missions for a solar sail involves a dive near the sun, where the light is intense, and sail efficiencies are high. For this reason, most sails are designed to tolerate much higher temperatures than one might expect. Going close to the Sun may be done for different mission aims: for exploring the solar poles from a short distance, for observing the Sun and its near environment from a nonKeplerian circular orbit the plane of which may be shifted some solar radii, for flying-by the Sun such that the sail gets a very high speed.

An unsuspected feature, until the first half of the Nineties, of the solar sail propulsion is to allow a sailcraft to escape the solar system with a cruise speed higher or even much higher than a spacecraft powered by a nuclear electric rocket system. The spacecraft mass to sail area ratio does not need to achieve ultra-low values, even though the sail should be an advanced all-metal sail. This flight mode is also known as the fast solar sailing. Proven mathematically (like many other astronautical items well in advance of their actual launches), such sailing mode has been considered by NASA/Marshall as one of the options for a future precursor interstellar probe exploring the near interstellar space beyond the heliosphere. ^[6]

Most theoretical studies of interstellar missions with a solar sail plan to push the sail with a very large laser Beam-powered propulsion Direct Impulse beam. The thrust vector (spatial)vector would therefore be away from the Sun and toward the target.

Limitations of solar sails

Solar sails don't work well, if at all, in low Earth orbit below about 800 km altitude due to erosion or air drag.^[7] Above that altitude they give very small accelerations that take months to build up to useful speeds. Solar sails have to be physically large, and payload size is often small. Deploying solar sails is also highly challenging to date.

Solar sails must face the sun to decelerate. Therefore, on trips away from the sun, they must arrange to loop behind the outer planet, and decelerate into the sunlight.^[8]

Some authorities have claimed that solar sails cannot go towards their light source. This is false. In particular, sails can go toward the sun by thrusting against their orbital motion. This reduces the energy of their orbit, spiraling the sail toward the sun.^[9]

Investigated sail designs

"Parachutes" would have very low mass, but theoretical studies show that they will collapse from the forces placed by shrouds. Radiation pressure does not behave like aerodynamic pressure.^[10] From http://antwrp. ... From http://antwrp. ...

The highest thrust-to-mass designs known (2007) were theoretical designs developed by Eric Drexler.^[11] He designed a sail using reflective panels of thin aluminum film (30 to 100 nanometres thick) supported by a purely tensile structure. It rotated and would have to be continually under slight thrust. He made and handled samples of the film in the laboratory, but the material is too delicate to survive folding, launch, and deployment, hence the design relied on space-based production of the film panels, joining them to a deployable tension structure. Sails in this class would offer accelerations an order of magnitude higher than designs based on deployable plastic films. K. Eric Drexler (born April 25, 1955) is best known for popularizing the potential of molecular nanotechnology. ... A nanometre (American spelling: nanometer, symbol nm) (Greek: Î½Î¬Î½Î¿Ï‚, nanos, dwarf; Î¼ÎµÏ„ÏÏŽ, metrÏŒ, count) is a unit of length in the metric system, equal to one billionth of a metre (or one millionth of a millimetre), which is the current SI base unit of length. ... Tension is a reaction force applied by a stretched string (rope or a similar object) on the objects which stretch it. ...

The highest-thrust to mass designs for ground-assembled deployable structures are square sails with the masts and guy lines on the dark side of the sail. Usually there are four masts that spread the corners of the sail, and a mast in the center to hold guide wires. One of the largest advantages is that there are no hot spots in the rigging from wrinkling or bagging, and the sail protects the structure from the sun. This form can therefore go quite close to the sun, where the maximum thrust is present. Control would probably use small sails on the ends of the spars.

In the 1970s JPL did extensive studies of rotating blade and rotating ring sails for a mission to rendezvous with Halley's Comet. The intention was that such structures would be stiffened by their angular momentum, eliminating the need for struts, and saving mass. In all cases, surprisingly large amounts of tensile strength were needed to cope with dynamic loads. Weaker sails would ripple or oscillate when the sail's attitude changed, and the oscillations would add and cause structural failure. So the difference in the thrust-to-mass ratio was almost nil, and the static designs were much easier to control. Image File history File links Sail-design-types. ... The JPL complex in Pasadena, Ca. ... This article is about the comet. ...

JPL's reference design was called the "heliogyro" and had plastic-film blades deployed from rollers and held out by centripetal forces as it rotated. The spacecraft's altitude and direction were to be completely controlled by changing the angle of the blades in various ways, similar to the cycle and collective pitch of a helicopter. Although the design had no mass advantage over a square sail, it remained attractive because the method of deploying the sail was simpler than a strut-based design. For other uses, see Helicopter (disambiguation). ...

JPL also investigated "ring sails" (Spinning Disk Sail in the above diagram), panels attached to the edge of a rotating spacecraft. The panels would have slight gaps, about one to five percent of the total area. Lines would connect the edge of one sail to the other. Weights in the middles of these lines would pull the sails taut against the coning caused by the radiation pressure. JPL researchers said that this might be an attractive sail design for large manned structures. The inner ring, in particular, might be made to have artificial gravity roughly equal to the gravity on the surface of Mars.

A solar sail can serve a dual function as a high-gain antenna. Designs differ, but most modify the metallization pattern to create a holographic monochromatic lens or mirror in the radio frequencies of interest, including visible light.

Pekka Janhunen from FMI has invented a type of solar wind sail called the electric solar wind sail[2]. It has little in common with the solar wind sail design externally, bacause the sails are substituted with straigthened conducting tethers (wires) which are placed radially around the host ship. The wires are electrically charged and thus an electric field is created around the wires. The electric field of the wires extends a few tens of metres into the surrounding solar wind plasma. Because the solar wind electrons react on the electric field similarly as on a concrete solar wind sail, the function radius of the wires is based on the electric field that is generated around the wire rather than the actual wire itself. This fact also makes it possible to maneuver a ship with electric solar wind sail by regulating the electric charge of the wires. A full-sized functioning electric solar wind sail would have 50-100 straightened wires with a length of about 20 km each. Finnish Meteorological Institute (Ilmatieteen laitos) is a government agency, which is a central place responsible for gathering and reporting weather data and forecasts in Finland. ... This article is about an authentication, authorization, and accounting protocol. ... In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. ...

Current progress

NASA has successfully tested deployment technologies on small scale sails in vacuum chambers.[3] Cosmos 1 solar sail. ... Cosmos 1 solar sail. ... An artists rendering of Cosmos 1 orbiting the Earth. ...

No solar sails have been successfully deployed as primary propulsion systems, but research in the area is continuing. On August 9, 2004 Japanese ISAS successfully deployed two prototype solar sails from a sounding rocket. A clover type sail was deployed at 122 km altitude and a fan type sail was deployed at 169 km altitude. Both sails used 7.5 micrometer thick film. The experiment was purely a test of the deployment mechanisms, not of propulsion.[4] is the 221st day of the year (222nd in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... The Japan Aerospace eXploration Agency (JAXA) is Japans aerospace agency. ... A micrometre (American spelling: micrometer, symbol Âµm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ...

A joint private project between Planetary Society, Cosmos Studios and Russian Academy of Science launched Cosmos 1 on June 21, 2005, from a submarine in the Barents Sea, but the Volna rocket failed, and the spacecraft failed to reach orbit. A solar sail would have been used to gradually raise the spacecraft to a higher earth orbit. The mission would have lasted for one month. A suborbital prototype test by the group failed in 2001 as well, also because of rocket failure. This article is in need of attention. ... Russian Academy of Sciences (Росси́йская Акаде́мия Нау́к) is the national academy of Russia. ... An artists rendering of Cosmos 1 orbiting the Earth. ... is the 172nd day of the year (173rd in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Location of the Barents Sea. ... Space launch vehicle Volna (wave in Russian), is a converted SLBM used for launching artificial satellites into Orbit. ...

A 15-meter-diameter solar sail (SSP, solar sail sub payload, soraseiru sabupeiro-do) was launched together with ASTRO-F on a M-V rocket on February 21, 2006, and made it to orbit. It deployed from the stage, but opened incompletely.^[12] Artists conception of ASTRO-F ASTRO-F (or Akari) is an infrared astronomy satellite developed by Japan Aerospace Exploration Agency, in cooperation with institutes of Europe and Korea. ... M-V rocket with the ASTRO-E satellite (Febr. ... is the 52nd day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

Sail materials

The best known material is thought to be a thin mesh of aluminium with holes less than ½ the wavelength of most light. Nanometre-sized "antennas" would emit heat energy as infrared. Although samples have been created, it is too fragile to unfold or unroll with known technology. Download high resolution version (3000x2171, 2078 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (3000x2171, 2078 KB) Wikipedia does not have an article with this exact name. ... A nanometre (American spelling: nanometer, symbol nm) (Greek: Î½Î¬Î½Î¿Ï‚, nanos, dwarf; Î¼ÎµÏ„ÏÏŽ, metrÏŒ, count) is a unit of length in the metric system, equal to one billionth of a metre (or one millionth of a millimetre), which is the current SI base unit of length. ...

The most common material in current designs is aluminized 2 µm Kapton film. It resists the heat of a pass close to the Sun and still remains reasonably strong. The aluminium reflecting film is on the Sun side. The sails of Cosmos 1 were made of aluminized PET film. A micrometre (American spelling: micrometer, symbol Âµm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... Kapton is a polyimide film developed by DuPont which can remain stable in a wide range of temperatures, from -269 Â°C to +400 Â°C. Kapton is used in, among other things, flexible printed circuits (flexible electronics) and Thermal Micrometeoroid Garments, the outside layer of spacesuits. ... Biaxially-oriented polyethylene terephthalate (boPET) polyester film is used for its high tensile strength, chemical and dimensional stability, transparency, gas and aroma barrier properties and electrical insulation. ...

Research by Dr. Geoffrey Landis in 1998-9, funded by the NASA Institute for Advanced Concepts, showed that various materials such as Alumina for laser lightsails and Carbon fiber for microwave pushed lightsails were superior sail materials to the previously standard aluminum or Kapton films.^[13] Geoffrey A. Landis emerged in the late 1980s as one of the foremost scientist-writers in the science fiction genre. ... NASA Institute for Advanced Concepts is apparently an organisation within NASA that funds research on advanced concepts, that is, not some boring present day concepts, but exciting future technologies. ... Aluminium oxide (or aluminum oxide) (Al2O3) is a chemical compound of aluminium and oxygen. ... Carbon fiber composite is a strong, light and very expensive material. ...

In 2000, Energy Science Laboratories developed a new carbon fiber material which might be useful for solar sails.^[14] The material is over 200 times thicker than conventional solar sail designs, but it is so porous that it has the same weight. The rigidity and durability of this material could make solar sails that are significantly sturdier than plastic films. The material could self-deploy and should withstand higher temperatures.

There has been some theoretical speculation about using molecular manufacturing techniques to create advanced, strong, hyper-light sail material, based on nanotube mesh weaves, where the weave "spaces" are less than ½ the wavelength of light impinging on the sail. While such materials have as-of-yet only been produced in laboratory conditions, and the means for manufacturing such material on an industrial scale are not yet available, such materials could weigh less than 0.1 g/m²^[15] making them lighter than any current sail material by a factor of at least 30. For comparison, 5 micrometre thick Mylar sail material weighs 7 g/m², aluminized Kapton films weighs up to 12 g/m²,^[16] and Energy Science Laboratories' new carbon fiber material weighs in at 3g/m².^[14] Molecular engineering is any means of manufacturing molecules. ... Look up Nanotube in Wiktionary, the free dictionary. ... Mylar is a trade name of DuPont Teijin Films of Hopewell, VA, United States, for biaxially-oriented polyethylene terephthalate (BOPET) polyester film used for its high tensile strength, chemical and dimensional stability, transparency, and electrical insulation. ... Kapton is a polyimide film developed by DuPont which can remain stable in a wide range of temperatures, from -269 Â°C to +400 Â°C. Kapton is used in, among other things, flexible printed circuits (flexible electronics) and Thermal Micrometeoroid Garments, the outside layer of spacesuits. ...

Applications

Robert Forward proposed the use of lasers to push solar sails, providing beam-powered propulsion. Given a sufficiently powerful laser and a large enough mirror to keep the laser focused on the sail for long enough, a solar sail could be accelerated to a significant fraction of the speed of light. To do so, however, would require the engineering of massive, precisely-shaped optical mirrors or lenses (wider than the Earth for interstellar transport), incredibly powerful lasers, and more power for the lasers than humanity currently generates. Robert Lull Forward commonly known as Robert L. Forward (August 15, 1932 - September 21, 2002) was a United States physicist and science fiction writer. ... For other uses, see Laser (disambiguation). ... Beam-powered propulsion is a class of spacecraft propulsion mechanisms that use energy beamed to the spacecraft from a remote power plant. ... The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness.[1] It is the speed of all electromagnetic radiation, including visible light, in a vacuum. ...

A potentially easier approach would be to use a maser to drive a "solar sail" composed of a mesh of wires with the same spacing as the wavelength of the microwaves, since the manipulation of microwave radiation is somewhat easier than the manipulation of visible light. The hypothetical "Starwisp" interstellar probe design would use a maser to drive it. Masers spread out more rapidly than optical lasers thanks to their longer wavelength, and so would not have as long an effective range. A hydrogen radio frequency discharge, the first element inside a hydrogen maser (see description below) A maser is a device that produces coherent electromagnetic waves through amplification due to stimulated emission. ... Starwisp is a hypothetical unmanned interstellar probe design proposed by Robert L. Forward. ...

Masers could also be used to power a painted solar sail, a conventional sail coated with a layer of chemicals designed to evaporate when struck by microwave radiation.^[17] The momentum generated by this evaporation could significantly increase the thrust generated by solar sails, as a form of lightweight ablative laser propulsion. Vaporization redirects here. ... Thrust is a reaction force described quantitatively by Newtons Second and Third Laws. ... Ablative Laser Propulsion or ALP is a form of beam-powered propulsion in which an external laser is used to burn off a plasma plume from a solid metal propellent, thus producing thrust. ...

To further focus the energy on a distant solar sail, designs have considered the use of a large zone plate. This would be placed at a location between the laser or maser and the spacecraft. The plate could then be propelled outward using the same energy source, thus maintaining its position so as to focus the energy on the solar sail. Binary zone plate: The areas of each ring, both light and dark, are equal. ...

Spacecraft fitted with solar sails can also be placed in close orbits about the Sun that are stationary with respect to either the Sun or the Earth, a type of satellite called a statite. This is possible because the propulsion provided by the sail offsets the gravitational potential of the Sun. Such an orbit could be useful for studying the properties of the Sun over long durations. A statite is a hypothetical type of artificial satellite that employs a solar sail to continuously modify its orbit in ways that gravity alone would not allow. ...

Such a spacecraft could conceivably be placed directly over a pole of the Sun, and remain at that station for lengthy durations. Likewise a solar sail-equipped spacecraft could also remain on station nearly above the polar terminator of a planet such as the Earth by tilting the sail at the appropriate angle needed to just counteract the planet's gravity. Additionally, it has been theorized by da Vinci Project contributor T. Pesando that solar sail-utilizing spacecraft successful in interstellar travel could be used to carry their own zone plates or perhaps even masers to be deployed during flybys at nearby stars. Such an endeavour could allow future solar-sailed craft to effectively utilize focused energy from other stars rather than from the Earth or Sun, thus propelling them more swiftly through space and perhaps even to more distant stars. However, the potential of such a theory remains uncertain if not dubious due to the high-speed precision involved and possible payloads required. World map with terminator (April) A composite image showing the terminator dividing night from day, running across Europe and Africa. ... The da Vinci Project is a privately-funded, volunteer-staffed attempt to launch a reusable manned suborbital spacecraft. ...

Future Visions

Despite the loss of Cosmos 1 (which was due to a failure of the launcher), scientists and engineers around the world remain encouraged and continue to work on solar sails. While most direct applications created so far intend to use the sails as inexpensive modes of cargo transport, some scientists are investigating the possibility of using solar sails as a means of transporting humans. This goal is strongly related to the management of very large (i.e. well above 1 km²) surfaces in space and the sail making advancements. Thus, in the near/medium term, solar sail propulsion is aimed chiefly at accomplishing a very high number of non-crewed missions in any part of the solar system and beyond.

Solar sails in fiction

Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Founded in Istanbul in 1991, Mavi Jeans designs a full collection of jeanswear, for young women and men. ... Sir Arthur Charles Clarke, CBE, Sri Lankabhimanya (16 December 1917 â€“ 19 March 2008) was a British (lived in Sri Lanka since 1956) science fiction author, inventor, and futurist, most famous for the novel 2001: A Space Odyssey, written in collaboration with director Stanley Kubrick, a collaboration which led also to... The Wind from the Sun (ISBN 0151968101) is a collection of short stories by science fiction writer Arthur C. Clarke. ... Poul William Anderson (November 25, 1926â€“July 31, 2001) was an American science fiction author of the genres Golden Age. ... John Holbrook Vance (born August 28, 1916 in San Francisco, California) is generally described as an American fantasy and science fiction author, though Vance himself has reportedly objected to such labels. ... The Mote in Gods Eye, by Larry Niven and Jerry Pournelle, is a science fiction novel that was first published in 1974. ... This article does not cite any references or sources. ... Jerry Eugene Pournelle, Ph. ... Rocheworld (1990), also known as The Flight of the Dragonfly (1984) is a science fiction novel by Robert Forward in which he uses a light sail propulsion system to set the crew on an interstellar mission. ... Robert Lull Forward, commonly known as Robert L. Forward, (August 15, 1932 - September 21, 2002) was an American physicist and science fiction writer. ... Tron is a 1982 Walt Disney Productions science fiction movie starring Jeff Bridges as Kevin Flynn (and Clu), Bruce Boxleitner as Alan Bradley (and Tron), Cindy Morgan as Lora (and Yori)and Dan Shor as Ram. ... Film poster for Star Wars Episode II: Attack of the Clones Star Wars Episode II: Attack of the Clones (2002) is the fifth Star Wars science fiction movie released and the second part of the prequel trilogy which began with Star Wars Episode I: The Phantom Menace. ... Count Dooku, also known as Darth Tyranus, is a fictional character from the Star Wars universe and Palpatines apprentice. ... This article is about a hypothetical method of space travel. ... Star Trek IV: The Voyage Home (Paramount Pictures, 1986; see also 1986 in film) is the fourth feature film based on the popular Star Trek science fiction television series. ... Space station Star Trek: Deep Space Nine (ST:DS9 or STDS9 or DS9 for short) is a science fiction television series produced by Paramount and set in the Star Trek universe. ... The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness.[1] It is the speed of all electromagnetic radiation, including visible light, in a vacuum. ... A tachyon (from the Greek (takhÃºs), meaning swift, fast) is any hypothetical particle that travels at superluminal velocity. ... Cordwainer Smith â€“ pronounced CORDwainer Smith â€“ was the pseudonym used by American author Paul Myron Anthony Linebarger (July 11, 1913 â€“ August 6, 1966) for his science fiction works. ... Heavens Reach is the third novel in the Uplift Storm series by David Brin. ... A cut-away diagram of an idealized Dyson shellâ€”a variant on Dysons original conceptâ€”1 AU in radius. ... Charles David George Charlie Stross (born Leeds, October 18, 1964) is a writer based in Edinburgh, Scotland. ... GSX-401FW This article is about a fictional mobile suit from the Cosmic Era timeline of the anime Gundam metaseries - specifically the ONA Gundam SEED C.E. 73: Stargazer. ... Mobile Suit (MS in short): Space Utility Instrumental Tactical Mobile Suits are humanoid weapon systems in the Gundam anime series. ... The Cosmic Era is the fictional timeline of the anime television series Mobile Suit Gundam SEED and its spinoff projects. ... Title of the series Mobile Suit Gundam SEED (or Gundam Seed) is an anime television series from Japan. ... For Nuclear Technologies like the Neutron Jammer and GENESIS please see Cosmic Era Superweapons for more information. ... Treasure Planet is a 2002 Academy Award nominated science fiction animated feature film produced by Walt Disney Feature Animation, and released by Walt Disney Pictures on November 27, 2002. ... The Outer Limits is an American television series. ... Enlightenment is a serial in the British science fiction television series Doctor Who, which was originally broadcast in four twice-weekly parts from March 1 to March 9, 1983. ... Bernard Werber (born September 18, 1961 in Toulouse) is the most famous French writer of science fiction of the 1990s and 2000s. ... This article is about the book. ... Pierre Boulle (20 February 1912 â€“ 30 January 1994) was a French novelist largely known for two famous works, The Bridge over the River Kwai (1952) and Planet of the Apes (1963). ...

Misunderstandings

Critics of the solar sail argue that solar sails are impractical for orbital and interplanetary missions because they move on an indirect course. However, when in Earth orbit, the majority of mass on most interplanetary missions is taken up by fuel. A robotic solar sail could therefore multiply an interplanetary payload by several times by reducing this significant fuel mass, and create a reusable, multimission spacecraft. Most near-term planetary missions involve robotic exploration craft, in which the directness of the course is unimportant compared to the fuel mass savings and fast transit times of a solar sail. For example, most existing missions use multiple gravitational slingshots to reduce necessary fuel mass, in order to save transit time at the cost of directness of the route.

There is also a misunderstanding that solar sails capture energy primarily from the solar wind high speed charged particles emitted from the sun. These particles would impart a small amount of momentum upon striking the sail, but this effect would be small compared to the force due to radiation pressure from light reflected from the sail. The force due to light pressure is about 5000 times as strong as that due to solar wind. A much larger type of sail called a magsail would employ the solar wind. A magnetic sail or magsail is a proposed method of spacecraft propulsion. ...

Technical Criticism of Solar Sail Concept

It has been proposed that momentum exchange from reflection of photons is an unproven effect that may violate the thermodynamical Carnot rule. This criticism was raised by Thomas Gold of Cornell, leading to a public debate in the spring of 2003.^[19] This criticism has been refuted by Benjamin Diedrich pointing out that the Carnot Rule does not apply to an open system. Further explanation of lab results demonstrating is provided. [5] James Oberg has also refuted Dr. Gold's analysis: "But ‘solar sailing’ isn’t theoretical at all, and photon pressure has been successfully calculated for all large spacecraft. Interplanetary missions would arrive thousands of kilometers off course if correct equations had not been used. The effect for a genuine ‘solar sail’ will be even more spectacular."[6] The Carnot cycle is a particular thermodynamic cycle, modeled on the Carnot heat engine, studied by Nicolas LÃ©onard Sadi Carnot in the 1820s and expanded upon by Benoit Paul Ã‰mile Clapeyron in the 1830s and 40s. ... This article is about Thomas Gold, an Austrian astrophysicist. ... James Edward Oberg (b. ...

Another alleged solution is that when reflected by a solar sail, a photon undergoes a Doppler shift; its wavelength increases (and energy decreases) by a factor dependent on the velocity of the sail, transferring energy from the sun-photon system to the sail.^[20] The Doppler effect is the apparent change in frequency or wavelength of a wave that is perceived by an observer moving relative to the source of the waves. ...

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