Field propulsion

{{Short description|Propulsion concepts and technologies}} {{distinguish|Spacecraft electric propulsion|Reactionless drive}} [[File:Advanced Composite Solar Sail System deployment.gif|thumb|Rendering of the deployment of a [[solar sail]] for the [[Solar sail#Advanced Composite Solar Sail System (ACS3)|Advanced Composite Solar Sail System (ACS3)]], released by [[NASA]] in 2023.]] [[Image:STS-75 Tethered Satellite System deployment.jpg|thumb|Deployment of the [[tethered satellite system]] during [[STS-75]] in 1996.]]

'''Field propulsion''' refers to [[propulsion systems|propulsion system]] concepts in which [[thrust]] arises from [[Coupling (physics)|interactions]] with external [[Field (physics)|fields]] or ambient [[Interplanetary medium|media]], rather than primarily from onboard [[Fuel|chemical propellant]].<ref name="NASA FP small 2024-03-17" /><ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|1}}{{efn|name=termusage|The term ''field propulsion'' appears explicitly in multiple sources cited in this article. Minami defined it as employing "a physical means to asymmetrically interact with the space vacuum".<ref name="Minami FP JBIS 2003" />{{rp|350}} Minami and Musha wrote that a "Field propulsion system can be propelled without mass expulsion" and that its thrust arises from interaction with "the substantial physical structure".<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|1}} Millis wrote: "For field propulsion, the fields themselves must act as the reaction mass".<ref name="Millis Coupling Gravity EM Spacetime 1995" />{{rp|95}} Myrabo's NASA contractor report also used ''field propulsion'' as a category heading in a taxonomy that grouped concepts under thermal, field, and photon headings.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|25-26}} NASA's later small-spacecraft survey uses the narrower label ''propellant-less propulsion systems'' for systems that "generate thrust via interaction with the surrounding environment".<ref name="NASA FP small 2024-03-17" />}} The idea developed alongside conventional [[rocket]]ry as a parallel line of thought in which a vehicle would "push off" its surroundings rather than rely entirely on carried propellant.<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|216-217}} Early ideas grew from studies of [[radiation pressure]] and electrically driven motion; later contractor and agency surveys organized advanced concepts under thermal, field, and photon headings.<ref name="Matloff Photon Sail 2004" />{{rp|1-2}}<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|25-26}} Several related propulsion systems discussed alongside field propulsion in the broader historical literature surveyed here have since been demonstrated in practice, including [[electrodynamic tether]]s in orbit, [[solar sail]] spacecraft such as [[IKAROS]], and terrestrial applications such as [[magnetic levitation|maglev]] transport, [[magnetohydrodynamics|MHD]] ship propulsion, and [[electrohydrodynamics|EHD]] thrust devices.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|25-26,I-2}}<ref name="NASA tether 1999-03-13" /><ref name="JAXA IKAROS 2010" /><ref name="Takezawa et al Yamato1 Jime 1994" /><ref name="Nature 2018 aeroplane et al" /> In narrower modern literature, related ''propellant-less propulsion'' discussions often focus on environment-coupled systems, while the historical contractor and survey literature treated field propulsion more broadly and sometimes grouped related terrestrial electromagnetic propulsion and some beamed-energy concepts within the same analytical framework.<ref name="NASA FP small 2024-03-17" /><ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|25-26,I-2}}<ref name="Gilland NIAC Plasma 2011" />{{rp|1-2}}

Related research has also examined [[Beam-powered propulsion|beamed-energy propulsion]], in which lasers, microwaves, or particle beams transmit power to a vehicle from a remote source, and more speculative proposals involving [[Spacetime|spacetime curvature]], [[vacuum polarization]], or [[zero-point energy]] interactions.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2,II-1}}<ref name="Millis BPPP NASA 1998" />{{rp|1-2}}<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|215-216,219}} [[NASA]]'s [[Breakthrough Propulsion Physics Program]] helped reframe the subject around conservation-law consistency, identifiable coupling mechanisms, and experimental reproducibility.<ref name="Millis BPPP NASA 1998" />{{rp|1-2,6}} Any claimed propulsion method that produces net thrust in a closed system without external interaction would violate [[conservation of momentum]], which follows from the spatial [[Translational symmetry|translation symmetry]] of physical law as expressed by [[Noether's theorem]].<ref name="Kim et al Physics WS" /><ref name="Millis BPPP NASA 1998" />{{rp|2}}

The subject has been treated by national [[space agency|space agencies]], academic research groups, and [[aerospace manufacturer|industry organizations]], and field propulsion concepts have appeared extensively in [[science fiction]], in many cases predating or paralleling the technical research. The influence has occasionally been direct: physicist [[Miguel Alcubierre]] said that his [[Alcubierre drive|warp metric]] was inspired by ''[[Star Trek]]'' terminology.<ref name="Alcubierre Warp 1994" /><ref name="Planetary Alcubierre 2014" />

==Background and history== {{Related|[[Non-rocket spacelaunch]]}} [[File:Johannes Kepler, portrait by Hans von Aachen.jpg|thumb|[[Johannes Kepler]] wrote of ideas analogous to [[solar sailing]] in 1610.]]

Traditional [[Rocket|rocketry]] has dominated [[Spacecraft propulsion|aerospace propulsion]] in the 20th and early 21st centuries.<ref name="NASA History of Rockets" /> Conventional rockets achieve motion by expelling mass, most commonly the [[combustion]] output from [[rocket propellant|chemical propellants]] to generate thrust via [[Newton's laws of motion#Third law|Newton's third law]], which is the familiar [[Space launch|rocket launch]] with [[Rocket engine#Principle of operation|explosive flame and smoke]] beneath it.<ref name="Sutton Rockets 2017" />{{rp|5-6}} Field propulsion concepts evolved as a parallel track, proposing instead that a spacecraft could "[[Propulsion|push off]]" its surrounding medium, converting environmental energy or momentum into [[acceleration]].<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|216-217}} In this article, ''field propulsion'' is used for [[propulsion systems|propulsion system]] concepts in which [[thrust]] arises from [[Coupling (physics)|interactions]] with external [[Field (physics)|fields]] or ambient [[Interplanetary medium|media]], rather than primarily from onboard [[Fuel|chemical propellant]], while noting that some later sources instead use the narrower label ''propellant-less propulsion'' for environment-coupled systems.<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|1}}<ref name="NASA FP small 2024-03-17" /> In the historical survey literature, however, the category was often drawn more broadly, extending to related externally powered and terrestrial electromagnetic concepts discussed within the same analytical family.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|25-26,I-2}}<ref name="NASA FP small 2024-03-17" />

While many proposals remained theoretical, certain environment-coupled systems were eventually demonstrated in space,<ref name="PS FP 2015-06-09" /><ref name="PS FP 2020 LightSail2" /> including [[solar sail]]s, [[magnetic sail]]s, and [[electrodynamic tether]]s, which couple with external [[photon]], [[Plasma (physics)|plasma]], or [[Magnetic field|magnetic fields]] instead of expelling [[working mass|onboard propellant]].<ref name="Gilland NIAC Plasma 2011" />{{rp|1-2}} Field propulsion is not a single technology but a spectrum of approaches, ranging from mature concepts that have been [[Test article (aerospace)|tested]] in flight to [[Theoretical spacecraft propulsion|highly speculative theoretical]] constructs.<ref name="Millis BPPP NASA 1998" />{{rp|2}}

===Pre-20th century to the 1910s=== The earliest field propulsion concepts began evolving prior to the 20th century. In 1610, [[Johannes Kepler]] wrote ''Dissertatio cum Nuncio Sidereo'' (''Conversation with the Messenger from the Stars'') to [[Galileo Galilei]], in response to Galilei's own ''[[Sidereus Nuncius]]'', describing the idea of winds in space propelling craft like the winds of the seas:<ref name="Kepler Quotes" /><ref name="Rosen Kepler" />{{rp|39}}

{{blockquote|As soon as somebody demonstrates the art of flying, settlers from our species of man will not be lacking [on the Moon and Jupiter] … Who would have believed that a huge ocean could be crossed more peacefully and safely than the narrow expanse of the Adriatic, the Baltic Sea or the English Channel? Provide ship or sails adapted to the heavenly breezes, and there will be some who will not fear even that void [of space]...}}

The physical basis for Kepler's intuition began to emerge over two centuries later. [[James Clerk Maxwell]] demonstrated in 1873 that [[electromagnetic radiation]] should be able to create pressure on physical surfaces.<ref name="Matloff Photon Sail 2004" />{{rp|1-2}} At the [[International Congress of Physics]] in 1900, [[Pyotr Lebedev]] presented ''Les forces de Maxwell-Bartoli dues à la pression de la lumière'', reporting experimental measurements of [[radiation pressure]] and providing the first quantitative confirmation of Maxwell's predictions with evidence that light exerts pressure on matter.<ref name="Lebedev FP 1900"/>{{rp|133-140}}<ref name="Rynin Vol 8 1932" />{{rp|332-333}} By 1905, [[Albert Einstein]] had [[Quantization (physics)|quantized]] Maxwell's findings to prove light particles could possess momentum.<ref name="Matloff Photon Sail 2004" />{{rp|2}}

===1920s-1950s=== [[File:Dynamo-electric machines. NAVASCUES, J, León, Spain. Aug. 21, 1928.png|thumb|Dynamo-electric machines, an early 1928 patent related to field propulsion.]]

In 1921, Tsiolkovsky published ''Extension of Man into Outer Space'', further exploring photon-based propulsion concepts.<ref name="Matloff Photon Sail 2004" />{{rp|2}} ''Перелеты на другие планеты'' (''Flights to Other Planets'') by [[Friedrich Zander]] was published in 1924 in ''Техника и жизнь'', a Russian science journal, describing concepts to achieve interplanetary flight by use of light-propelled "screens made of extremely thin sheets".<ref name="Zander FP 1924" /> Zander was reportedly inspired in this work by his colleague Tsiolkovsky's own research on the topic.<ref name="Matloff Photon Sail 2004" />{{rp|2}}

Between 1928 and 1932, [[Nikolai Rynin]] published ''Mezhplanetnye Soobshcheniya'' (''Interplanetary Flight and Communication''), a nine-volume Russian-language encyclopedia that the [[National Air and Space Museum]] described as the first encyclopedia on the history and theory of aerospace technology and spaceflight.<ref name="NASM Rynin" /> Its coverage included radiation-pressure propulsion and beamed-energy concepts,<ref name="Rynin Vol 1 1928" /> and the work of Lebedev, Tsiolkovsky, Goddard, [[Hermann Oberth]], and [[Robert Esnault-Pelterie]].<ref name="Rynin Vol 8 1932" />{{rp|332-333}} Rynin's first volume, ''Dreams, legends, and early fantasies'' (1928), organized spacecraft energy sources into three categories: energy transmitted from Earth to the vehicle, energy carried onboard, and energy derived from outer space; the last including "radiation pressure to bear on special large screens around the vehicle," an explicit description of photon-pressure propulsion.<ref name="Rynin Vol 1 1928" /> Rynin observed that the work surveyed in his encyclopedia "clearly shows that different people in different countries independently came to the same conclusion" regarding the feasibility of interplanetary travel.<ref name="Rynin Vol 8 1932" />{{rp|2}}

While encyclopedic surveys were documenting the theoretical landscape, parallel experimental work was emerging in Europe. In 1928, J. Navascués of [[León, Spain]] described a field coupled [[dynamo]]-electric machine concept "producing translatory motion of machine by current reaction with earth's field", in which "Propulsion is caused by cutting with a closed conducting turn the earth's [[magnetic flux]]".<ref name="Navascués FP 1928" />{{rp|7231}} After the 1930s, related field propulsion research concepts reached a lull in public published activity for over a decade through and after [[World War II]], appearing mainly in science fiction rather than in sustained technical development.<ref name="Choueiri FP 2004" />{{rp|12}}

The first clear postwar reappearance of these propulsion concepts in open scientific literature was in the 1958 [[Franklin Institute]] astronautics lecture series. H.W. Ritchey, vice-president of [[Thiokol]] and head of its rocket program,<ref name="Getty Ritchey" /> highlighted 'Field Propulsion' concepts, describing 'the use of fields' as a way to avoid an [[Jet engine|exhaust jet]].<ref name="Franklin FP Ritchey 1957" />{{rp|46-47}} In the same monograph, Israel Levitt, director of the Institute's [[Franklin Institute#Theaters|Fels Planetarium]], described solar propulsion methods including [[Krafft Arnold Ehricke]]'s solar thermal concepts, [[Richard Garwin]]'s radiation pressure sail proposals, and [[photon rocket]] research by Kurl Stanukovitch of Russia.<ref name="Franklin FP Levitt 1957" />{{rp|189-190,191-192,192-193}} U.S. Air Force general Donald L. Putt, who led [[Operation Paperclip]] after World War II,<ref name="Putt NASM" /> predicted that upcoming spacecraft would deploy "photo or ion field-type propulsion".<ref name="FP Globe 1958-05-31" />{{rp|6}}

===1960s-1970s=== [[File:Lspn comet halley.jpg|thumb|[[NASA]] and the [[Battelle Memorial Institute]] researched a [[solar sail]] mission to intercept [[Halley's Comet]] in the 1970s.]]

As spaceflight programs expanded throughout the 1960s, contractor studies for the [[U.S. Air Force]] and NASA increasingly organized advanced propulsion concepts under three main headings, Thermal, Field, and Photon, so that unconventional ideas could be compared within a common analytical framework.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|26}} A 1972 report from the [[Air Force Research Laboratory|Air Force Rocket Propulsion Laboratory]], followed by Jet Propulsion Laboratory studies in 1975 and 1982, carried this framework forward in published roadmaps. These studies emphasized "infinite [[specific impulse]]" systems that would obtain energy or [[working fluid]] from the ambient environment, and suggested that advances in lasers and superconductors could revive earlier discarded concepts such as laser propulsion or [[ramjets]].<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-1,25-26,406}} Later reviews characterized propulsion research in this period as driven by unrestricted creativity and "free-thinking".<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2}}

Terrestrial field propulsion concepts also attracted attention during this period. [[United Press International]] reported in 1964 on a proposal from the [[Westinghouse Air Brake Company]] to link [[Youngstown, Ohio]] with [[Pittsburgh]] via a "super conductor magnetic field propulsion" [[Transit Expressway Revenue Line|transit system]].<ref name="UPI FP 1964-01-03" />{{rp|9}} The ''[[Chicago Tribune]]'' later reported on early NASA advocacy of what was then called "field resonance propulsion," noting that related [[magnetohydrodynamics]] research had begun in 1971 as an extension of training astronauts on [[solar physics]].<ref name="Chicago Tribune FP 1980-01-29" />{{rp|15}}

Photon-pressure propulsion concepts also advanced through dedicated study programs. NASA funded the [[Battelle Memorial Institute]] in 1973 under Jerome L. Wright to study solar sailing concepts for a [[Halley's Comet]] intercept. In 1976, a formal solar sail rendezvous proposal managed by [[Louis Friedman]] at the [[Jet Propulsion Laboratory]] was submitted to NASA, but the sail concept was dropped in 1977 in favor of [[solar electric propulsion]], and the comet mission itself was later canceled.<ref name="Matloff Photon Sail 2004" />{{rp|2}}

===1980s=== In the 1980s, earlier classification frameworks began giving way to attempts to identify and organize specific physical coupling mechanisms capable of producing measurable thrust. In 1980, NASA scientist Al Holt noted that proposed models for field propulsion interactions in this era ranged from Albert Einstein's [[united field theory]] efforts to work by "serious 'amateurs'," reflecting how wide the speculative literature around such ideas had become by that period.<ref name="Holt FP 1980 NTRS" /> That year, Holt was quoted by the ''Chicago Tribune'' in his advocacy of field propulsion: "One of the most important things to me is to help break down the inhibiting mental attitude that space-time field interactions will remain in the realm of [[science fiction]] for hundreds of years."<ref name="Chicago Tribune FP 1980-01-29" />{{rp|18}} Holt argued that progress toward field-dependent propulsion would require a dedicated "field physics laboratory" to quantify relationships among gravitation, electromagnetism, and spacetime structure, framing the potential payoff as performance beyond then-leading aircraft and spacecraft such as the [[Space Shuttle]], [[SR-71A]], and [[F-16]].<ref name="Holt FP 1980 NTRS" />

Solar sail engineering also advanced institutionally during this period: JPL's Halley studies compared square and [[heliogyro]] sail architectures, with the latter using long rotating blades as sails and favored for deployment,<ref name="Friedman Solar sailing 1978" /> while the World Space Foundation fabricated and ground-deployed a 20 m sail and built a 30 m sail stowed in a deployment structure.<ref name="Garner Solar Sail Summary 1999" />{{rp|2}} A backup solar sail mission to [[Comet Encke]] was also considered in 1983 as an alternative to intercepting Halley's comet.<ref name="Friedman Solar sailing 1978" />

The ''[[Huntsville Times]]'' reported on a program by [[TRW Inc.]]'s Defense and Space Systems Group researching magnetic field based field propulsion, called "force field propulsion", for vehicle launch applications.<ref name="Huntsville FP 1980-10-27" />{{rp|4}} [[Robert L. Forward]] in 1984 extended beamed-sail studies to the interstellar scale, suggesting that phased solar-system lasers could impart sustained acceleration to ultralight sails across astronomical distances, and potential interstellar exploration within a human lifetime.<ref name="Forward lightsails 1984" />{{rp|187,193}} By the late 1980s, magnetic sails emerged as a proposed propellantless concept that would use a [[Superconductor|superconducting]] loop to deflect the solar wind or interstellar plasma, and thereby generate thrust or drag without expelling onboard [[reaction mass]].<ref name="ZubrinAndrews1991" />{{rp|197-198,203}} The 1980s were a major period of solar sailing research publication, with materials created by a variety of researchers globally, bookended by attempts in 1979 and 1992 by the World Space Foundation and the [[Columbus Quincentenary|Christopher Columbus Quincentenary Jubilee Commission]] to promote a solar sailing race to the moon.<ref name="Matloff Photon Sail 2004" />{{rp|1-2}}

===1990s=== [[File:Yamato 1 Left Front View at Kobe Maritime Museum November 10, 2012 01.jpg|thumb|''[[Yamato 1]]'' on display in [[Kobe]], Japan.]]

Terrestrial electromagnetic propulsion concepts reached operational demonstration in the early 1990s. In 1990, the ''[[Daily Telegraph]]'' reported on Japanese development work toward a magnetohydrodynamic propulsion ship, including plans to install the magnetic propulsion equipment and conduct at-sea testing.<ref name="Telegraph FP 1990-04-19" />{{rp|11}} By 1991–1992, the Ship & Ocean Foundation's experimental ship ''[[Yamato 1]]'' had been completed and successfully propelled by superconducting MHD thrusters during harbor trials in [[Kobe Harbor|Kobe]].<ref name="Takezawa et al Yamato1 Jime 1994" />{{rp|402}}<ref name="Seattle Times Yamato1 1992-07-20" /> Parallel investment in magnetic field propulsion for ground transport was also accelerating: in 1992, the ''New York Times'' described U.S. investment in [[maglev]] development, noting that maglev trains would be lifted on magnetic cushions and propelled along a [[Railway track|guideway]] by alternating magnetic fields that create a "magnetic wave".<ref name="NYT maglev 1991-03-23" />{{rp|9}} The report said Congress had authorized a six-year, $700 million demonstration program and noted existing demonstration systems in Germany and Japan, including a reported speed record of 273 miles per hour on a test track.<ref name="NYT maglev 1991-03-23" />{{rp|9}}

Electrodynamic work matured across the decade. The Plasma Motor Generator flight in 1993 was later described by NASA as the most sophisticated and most successful electrodynamic-tether mission yet flown.<ref name="NASA tether 1999-03-13" /><ref name="Cosmo Lorenzini SR 1997" />{{rp|153-155,188}} [[STS-75]] in 1996 deployed the TSS-1R [[Tethered Satellite System]] payload aboard {{OV|Columbia|full=no}}, validating high-voltage electrodynamic behavior in orbit and proving the functionality of the [[space tether]] field propulsion concept; NASA described it as the first tethered-satellite mission and the longest structure yet flown in space.<ref name="NASA tether 1999-03-13" /><ref name="Cosmo Lorenzini SR 1997" />{{rp|153-155,188}} Beamed-energy propulsion concepts also reached flight-test maturity during this period. In 1997, the laser-propelled [[Lightcraft]] was successfully flown in a series of experiments at the High Energy Laser Systems Test Facility at [[White Sands Missile Range]] under a joint USAF/NASA flight demonstration program.<ref name="Lightcraft AIAA 1998" />{{rp|1}}

NASA's [[Breakthrough Propulsion Physics Project]] (BPP) in 1998 reframed field propulsion from a catalog of ideas into a research program defined by [[Falsifiability|falsifiable]] physical requirements, establishing conservation-law consistency, measurable coupling mechanisms, and experimental reproducibility as the central benchmarks for evaluating advanced propulsion concepts.<ref name="Millis BPPP NASA 1998" />{{rp|1-2,6}} The program organized research around three goals: propulsion with no propellant mass, maximum physically possible transit speeds, and breakthrough energy sources.<ref name="Millis BPPP NASA 1998" />{{rp|1,3-4}} Marc Millis of BPP framed the related "space coupling propulsion" problem as requiring a tangible reaction-mass-like property of the vacuum and a controllable coupling mechanism that yields net external thrust.<ref name="Millis Coupling Gravity EM Spacetime 1995" />{{rp|93,94-95,95}} BPP raised the question of whether propellantless effects could exist without violating conservation of momentum and energy, and the more speculative end of the spectrum — concepts that couple to the environment without carrying reaction mass — remained in the research phase.<ref name="Millis BPPP NASA 1998" />{{rp|1-2,6}}<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|215-216}}

===21st century=== [[File:IKAROS solar sail.jpg|thumb|Depiction of [[IKAROS]], the first spacecraft to use a [[solar sail]] as its main propulsion system.]] [[File:Plasma brake in low Earth orbit.jpg|thumb|The plasma brake consists of a thin wire, that, when charged, creates [[electrostatic]] drag in the [[ionosphere]] and can [[deorbit]] satellites.]]

The [[British National Space Centre]] and [[Society of British Aerospace Companies]] began organizing an annual field propulsion research conference in 2001, inaugurated in [[Brighton]] at the [[Institute of Development Studies]], with initial delegates including [[Harry Kroto]].<ref name="FP Conference page 2001" /><ref name="Observer FP 2001-01-07" />{{rp|13}} [[British Aerospace]] was confirmed in 2001 to have initiated a research program called "Project Greenglow" to research "the possibility of the control of gravitational fields."<ref name="BBC Greenglow 2016-03-23" /><ref name="Observer FP 2001-01-07" />{{rp|13}} As demonstrated systems accumulated flight heritage, research programs continued exploring more speculative coupling mechanisms.

Subsequent work largely extended this research, examining whether identifiable environmental interactions could meet the same [[conservation law]] and measurement criteria. Later [[NASA Institute for Advanced Concepts]] (NIAC) studies continued in the same mold, examining whether [[Alfvén wave]] plasma interactions might provide quasi-propellantless thrust.<ref name="Gilland NIAC Plasma 2011" />{{rp|1–2}} Yoshinari Minami of the [[Advanced Space Propulsion Investigation Committee]] argued in 2003 that a potential propulsion "breakthrough" could rely on field propulsion, defined as employing "a physical means to asymmetrically interact with the space vacuum."<ref name="Minami FP JBIS 2003" />{{rp|350}} By 2009, a recognized category of 'breakthrough propulsion concepts' had emerged in the interstellar transport literature, encompassing [[warp drive]], [[Wormhole|traversable wormholes]], and [[Vacuum energy|vacuum-energy]] ideas, though the same literature noted strong skepticism about claims that appeared to conflict with conventional demonstrated physics.<ref name="Czysz Bruno FP 2009" />{{rp|450-451}} Millis summarized the matter as: "For field propulsion, the fields themselves must act as the reaction mass."<ref name="Millis Coupling Gravity EM Spacetime 1995" />{{rp|95}}

While further research and study continued, new environment-coupled propellantless systems were launched into space. [[IKAROS]] (Interplanetary Kite-craft Accelerated by Radiation Of the Sun), launched by the [[JAXA|Japan Aerospace Exploration Agency]] (JAXA) on May 21, 2010, was the first spacecraft to use a solar sail as its main propulsion system.<ref name="NASA Chronicle 2018" /> [[LightSail|LightSail 1]] and LightSail 2 flew between 2015 and 2019, with functional sail-type propellantless systems active in [[outer space]].<ref name="PS FP 2015-06-09" /><ref name="PS FP 2020 LightSail2" /> NASA's Advanced Composite Solar Sail System (ACS3), launched on April 23, 2024, tested next-generation composite-boom solar-sail technology in orbit, and mission operators confirmed full sail deployment on August 29, 2024.<ref name="NASA ACS3 what-is" /><ref name="NASA ACS3 deploy 2024" /> Related electrostatic sail concepts also moved into in-space technology-demonstration phases in the 2020s, with AuroraSat-1 launching in 2022 as a plasma-brake technology demonstrator and Foresail-1p launching in 2025 with a [[plasma brake]] experiment intended to enable the first-ever space measurements of [[Coulomb]] drag for [[Orbital mechanics|orbital change]].<ref name="NASA SOA propulsion 2024" /><ref name="Aalto Foresail-1p 2025" />

===Arts and culture=== [[File:Godwin man in the moone cropped contrast brightness adjusted.png|thumb|The [[Book frontispiece|frontispiece]] of the second edition of Francis Godwin's ''[[The Man in the Moone|Man in the Moone]]'', 1659.]] [[File:Star Trek Warp Field.svg|thumb|A representation of a ''Star Trek'' "warp bubble".]]

Field propulsion concepts have appeared across literature, film, and television, in many cases predating or paralleling the technical development of the technologies and theories described in this article. Several fictional propulsion systems bear recognizable resemblances to environment-coupled, electromagnetic, or spacetime-interaction concepts later studied in aerospace research.

Fictional antigravity and photon-propulsion ideas emerged well before the underlying physics was formalized. The ''[[The Encyclopedia of Science Fiction|Encyclopedia of Science Fiction]]'' traces fictional gravity counteraction from [[Francis Godwin]]'s ''[[The Man in the Moone]]'' (1638), through [[George Tucker (author)|George Tucker]]'s ''[[A Voyage to the Moon (Tucker novel)|A Voyage to the Moon]]'' (1827) and its antigravity metal "lunarium," to [[Percy Greg]]'s coinage of "apergy" as an antigravity spacecraft propulsion force in ''[[Across the Zodiac]]'' (1880).<ref name="SFE Antigravity" /><ref name="SFE Apergy" /> The earliest of these treated the concept in quasi-scientific rather than purely magical terms.<ref name="SFE Antigravity" /> A more direct link between fiction and physics appeared in ''Aventures extraordinaires d'un savant russe'' (''The Extraordinary Adventures of a Russian Scientist'', 1888–1896) by [[Georges Le Faure]] and Henry de Graffigny, which featured photon-propelled mirror spacecraft; [[Colin R. McInnes]] noted in his 1999 book ''Solar Sailing'' that the story may have been inspired by James Clerk Maxwell's 1873 research into radiation pressure, an early forebear of field propulsion.<ref name="Matloff Photon Sail 2004" />{{rp|1-2,48}}<ref name="Miller Sail Gizmodo 2014-03-13" />

As technical rocketry advanced in the early 20th century, pulp fiction kept pace with its own propulsion inventions. [[H. G. Wells]]'s ''[[The First Men in the Moon]]'' (1901) popularized gravity shielding through "[[cavorite]]," a material used to construct a sphere capable of leaving Earth without expelling propellant.<ref name="SFE Antigravity" /> Similar ideas proliferated across the pulp era: [[Edgar Rice Burroughs]]'s [[Barsoom]] series, beginning with ''[[A Princess of Mars]]'' (serialized 1912), described Martian airships propelled by a stored "eighth ray" used for lift and maneuvering rather than aerodynamic wings or rocket thrust,<ref name="Burroughs Barsoom" /> while ''[[Armageddon 2419 A.D.]]'' by [[Philip Francis Nowlan]] (1928) described "repellor anti-gravity rays" used as "legs" for airships, alongside "inertron," a substance that reacts to gravity opposite to normal matter.<ref name="Nowlan Armageddon" /> The [[Buck Rogers]] comic strip, launched in 1929, carried Nowlan's repulsor-beam and inertron concepts into the visual medium.<ref name="Nowlan Armageddon" /> The ''Encyclopedia of Science Fiction'' credited [[E. E. Smith]]'s ''[[Spacehounds of IPC]]'' (1931) as containing the first use of the term "force field" in science fiction.<ref name="SFE Force Field" />

By mid-century, science fiction was moving beyond individual gadgets toward propulsion concepts with explicit theoretical rationales. The ''Encyclopedia of Science Fiction'' attributes early use of "space warp" and "hyperspace" terminology in the context of interstellar travel to [[John W. Campbell]]'s ''[[Islands of Space]]'' (serialized 1931 in ''[[Amazing Stories Quarterly]]''; published as a novel in 1957).<ref name="SFE Space Warp" /><ref name="SFE Hyperspace" /> [[James Blish]]'s [[Cities in Flight]] series, beginning with "Bindlestiff" (December 1950, ''[[Astounding Science Fiction]]''), introduced the "[[Spindizzy (Cities in Flight)|spindizzy]]," formally the Dillon-Wagoner Graviton Polarity Generator.<ref name="SFE Spindizzy" /> The ''Encyclopedia of Science Fiction'' described the spindizzy as, in its day, "one of the best-loved items of sf Terminology," and noted that Blish gave the device a rationale rooted in theoretical physics, in which gravity fields are generated or cancelled by rotation owing to a fictional "Blackett-Dirac effect."<ref name="SFE Spindizzy" /> The National Air and Space Museum identified ''[[Forbidden Planet]]'' (1956) as the first film to depict a [[faster-than-light]] [[starship]] built by humans;<ref name="Smithsonian FP 2021-01-27" /> ''[[Time (magazine)]]'' described the starship's propulsion as a "quanto-gravitetic hyperdrive," and the published screenplay text includes the same phrasing in its opening narration.<ref name="Time FP 1956-04-09" />

Fiction magazines of this era also served as platforms for promoting claimed real-world propulsion devices. The [[Dean drive]], a claimed reactionless device built by [[Norman L. Dean]], received extensive promotion from John W. Campbell in ''Astounding Science Fiction'' beginning in 1960.<ref name="Campbell Space Drive 1960" />{{rp|83-106}}<ref name="Campbell Instrumentation Dean 1960" />{{rp|95-99}} Campbell published photographs of the device operating on a bathroom scale,<ref name="Campbell Report Dean 1960" />{{rp|4-7}} and the June 1960 cover of ''Astounding'' featured a painting of a United States submarine near Mars supposedly propelled by a Dean drive.<ref name="Campbell Space Drive 1960" />{{rp|1}} In 1984, physicist Amit Goswami wrote that the Dean drive had become so embedded in genre consciousness that "it is now customary in SF circles to refer to a reactionless drive as a Dean drive."<ref name="Goswami 1985" />{{rp|23}} [[Cordwainer Smith]]'s "The Lady Who Sailed The Soul" (''[[Galaxy Science Fiction]]'', April 1960) is among the earliest clearly sourced fictional treatments of photon-pressure sailing as a spacecraft propulsion method.<ref name="SFE Solar Wind" /> ''[[The Visual Encyclopedia of Science Fiction]]'' catalogued antigravity, the Dean drive, inertialess drive, sails, and spindizzy as distinct propulsion categories for space travel in the genre.<ref name="Ash 1977" />

The influence between fiction and field propulsion research became most visible through television. ''[[Star Trek: The Original Series]]'' (premiered September 8, 1966) made "warp drive" and "[[tractor beam]]" household terms.<ref name="SFE Tractor Beam" /><ref name="Prucher 2007" />{{rp|167}} In addition to popularizing the concept of warp drives, the ''Star Trek'' franchise was recognized by the [[Space Frontier Foundation]] for their portrayal of solar sail technologies in the ''[[Star Trek: Deep Space Nine]]'' episode "[[Explorers (Star Trek: Deep Space Nine)|Explorers]]", where astronauts construct and fly a lightsail ship.<ref name="SFF 1990s Timeline" /><ref name="DS9 Companion 2000" />{{rp|236-237}} ''Star Trek'' would later introduce a biologically mediated propulsion system with ''[[Star Trek: Discovery]]''{{'s}} [[spore drive]], which uses a subspace fungal network for instantaneous travel.<ref name="Koch Discovery Spore 2018" /> Physicist [[Miguel Alcubierre]] stated that his 1994 theoretical warp metric, a solution formulated within general relativity describing the expansion of spacetime behind and contraction in front of a theoretical spacecraft, was directly inspired by the terminology used in ''[[Star Trek]]'';<ref name="Alcubierre Warp 1994" /> [[The Planetary Society]] described him as having developed the model "inspired by Star Trek."<ref name="Planetary Alcubierre 2014" /> Alcubierre's warp metric remains one of the clearest documented cases in which a science fiction concept directly catalyzed formal physics research into field propulsion.

==Definitions== Advanced-propulsion survey frameworks have grouped candidate concepts under headings such as thermal propulsion, field propulsion, and photon propulsion.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|26}}{{efn|name=termusage}} In that broader historical literature, ''field propulsion'' was not always used as a strict synonym for modern propellantless propulsion; depending on the framework, it could also encompass related beamed-energy concepts and terrestrial field-matter coupling systems treated within the same analytical family.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|25-26,I-2}} By contrast, propellantless propulsion in the narrower modern sense produces thrust through interaction with the surrounding environment rather than by expelling reaction mass.<ref name="NASA FP small 2024-03-17" /> Later usage, as in NIAC studies of environment-coupled momentum exchange, restricts the term to systems that derive thrust from external fields or media without expelling onboard reaction mass.<ref name="Gilland NIAC Plasma 2011" />{{rp|1-2}} The boundaries of the term have therefore varied across successive classification frameworks, program definitions, and research criteria over more than a century of use.<ref name="Millis BPPP NASA 1998" />{{rp|1-2}} This article discusses the subject across that full historical range as documented in the source literature.

[[File:Solar wind flow.gif|thumb|upright=1|Artist's impression of [[solar wind]] flow around Earth's [[magnetosphere]].]] Examples of field propulsion technologies include systems that attempt to draw on the photon field of sunlight, the [[charged particles]] of the [[solar wind]], or the [[Magnetosphere|magnetic fields]] of planetary environments.<ref name="Gilland NIAC Plasma 2011" />{{rp|1-2}} Broad definitions often include solar sail systems.<ref name="JAXA IKAROS 2010" /><ref name="Johnson et al NASA 2013" />{{rp|3}} Magnetic sail concepts, proposed by Dana Andrews and [[Robert Zubrin]], exemplify this approach.<ref name="ZubrinAndrews1991" />{{rp|197}} In the broader historical literature, related terrestrial electromagnetic field-matter systems such as [[electrohydrodynamics]] (EHD) and [[magnetohydrodynamics]] (MHD) were also sometimes discussed within the same field-propulsion family, alongside more speculative proposals involving [[general relativity]], [[quantum field theory]], or [[zero-point energy]].<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2,IX-14-15,IX-33,XIII-1-3}}<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|215-216,219}}

Conservation of momentum is a fundamental requirement of propulsion systems because momentum is always conserved.<ref name="Millis BPPP NASA 1998" />{{rp|2}} This conservation law is implicit in the published work of [[Isaac Newton]] and Galileo Galilei, but arises on a fundamental level from the spatial [[Translational symmetry|translation symmetry]] of the laws of physics, as given by [[Noether's theorem]].<ref name="Kim et al Physics WS" /> Open systems comply with the [[conservation of momentum]] by transferring it to or from the surrounding environment.<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|216-217}} Conservation laws can be satisfied in field propulsion via interaction with "a mass, a massive body, electromagnetic radiation, and space as a vacuum," as Minami described, adding that the "most promising interpretation" is treating vacuum as "a kind of reaction mass."<ref name="Minami FP JBIS 2003" />{{rp|351}}

For instance, terrestrial MHD drives accelerate conductive fluids using [[electromagnetic fields]], resulting in thrust through the [[Lorentz force]] in a surrounding reaction medium such as seawater or plasma.<ref name="Takezawa et al Yamato1 Jime 1994" /><ref name="Gilmore Barrett 2015" />{{rp|2}} Environment-coupled space approaches such as sails, tethers, or plasma-wave coupling instead exchange momentum with ambient photons, plasma, or magnetic fields, and remain possible only if the method of external coupling is strong enough.<ref name="Gilland NIAC Plasma 2011" />{{rp|1-2,11-12}}

In practice, the viability of any open field-coupled concept depends on coupling strength to the surrounding environment. For example, momentum exchange with the solar wind or a magnetosphere scales with local plasma density, magnetic-field magnitude, and wave/field interaction efficiency; in weak or highly variable environments, thrust and control authority are correspondingly limited.<ref name="Gilland NIAC Plasma 2011" />{{rp|7-10}}

Any propulsion method that claims to generate net thrust in a closed system without external interaction violates the conservation of momentum, which follows from the spatial translation symmetry of physical law (Noether's theorem).<ref name="Kim et al Physics WS" /><ref name="Millis BPPP NASA 1998" />{{rp|2}} Some speculative field propulsion concepts may require extensions to established physical theories, including [[Physics beyond the Standard Model|beyond the Standard Model]] of [[particle physics]] and [[cosmology]].<ref name="Dröscher Hauser" />{{rp|9}} Millis notes that proposed "[[space drive]]" schemes where forces act only internally produce no net motion, and relates this "net external force requirement" to the conservation of momentum.<ref name="Millis 1996-07-16" />{{rp|2-3}}

===Beamed-energy propulsion=== [[File:LightSail 2 with deployed solar sail.png|thumb|[[LightSail]]-2 with deployed [[solar sail]], July 23, 2019.]]

In the broader historical literature used here, [[beam-powered propulsion]] was often discussed alongside field propulsion because it shifted energy supply offboard and, in some concepts, also drew working fluid or momentum exchange from the surroundings, even though many such systems do not fit the narrower modern propellantless-only sense.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2,II-1,IX-14-IX-15}}<ref name="NASA FP small 2024-03-17" /> Beam-powered propulsion sends power from a remote source directly to a spacecraft propulsion system using directed-energy technologies such as lasers, microwaves, or relativistic charged-particle beams. A NASA contractor report surveyed such concepts, seeking large gains in payload, range, and terminal velocity beyond chemical rocket performance.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2,II-1}} The report identified enabling technologies (e.g., higher-current superconductors, potential room-temperature superconductors, [[metallic hydrogen]]) as then-potential paths to field propulsion prospects.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2}}

A study from the Air Force Research Laboratory concluded that researchers should prioritize concepts that draw both working fluid and energy from surroundings, because of their implications for outstanding performance.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2}} Proposals also include advanced electrostatic and MHD-based concepts that could leverage charged particle interactions with atmospheric fields or ionospheric plasmas and [[Earth's magnetic field|geomagnetic fields]] to produce directed motion.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|IX-14-15,IX-33,XIII-1-3}} Some approaches use atmospheric or environmental material as working fluid or interaction medium, drawing reaction mass or momentum exchange from the ambient environment rather than from onboard propellant.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2,IX-14-IX-15}} The study suggested improvements in technologies like high-power lasers or new energy transfer methods could revitalize previously discarded propulsion ideas, including laser propulsion and infinite-Isp ramjets.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2}}

===Ambient plasma-wave propulsion=== NIAC studies proposed "ambient plasma wave propulsion" in which RF energy is coupled into ambient plasma using a spacecraft antenna, generating Alfvén waves, low-frequency disturbances that travel along ambient magnetic field lines in plasma; the report describes the wave as adding momentum to the antenna and spacecraft and thereby providing thrust as a "truly propellantless propulsion system".<ref name="Gilland NIAC Plasma 2011" />{{rp|1-2}} The 2011 Phase I assessment found the approach technically immature but potentially enabling if sensitivity and power challenges can be overcome.<ref name="Gilland NIAC Plasma 2011" />{{rp|1,25-26}}

===Theoretical proposals=== [[File:Alcubierre Metric, Nasa, Sonny White 2011-09-02.png|thumb|Alcubierre metric, related to [[Alcubierre drive|Alcubierre drives]], by [[Harold G. White]], [[NASA]] [[Johnson Space Center]]. It depicts a 'warp bubble' in which spacetime [[Expansion of the universe#Dynamics of cosmic expansion|expands]] behind and [[Scale factor (cosmology)#Detail|contracts]] in front of an example spacecraft as a theoretical propulsion concept.]]

NASA's Breakthrough Propulsion Physics (BPP) memo framed research questions at the limits of physics, no-propellant propulsion, ultimate transit speeds, and breakthrough energy production, explicitly to sort physically testable ideas from non-viable claims.<ref name="Millis BPPP NASA 1998" />{{rp|1}} Field propulsion alone was described as insufficient for practical interstellar exploration because no propulsion theory currently exceeds the [[speed of light]], requiring a navigation theory as a secondary solution alongside propulsion theory.<ref name="Minami FP Practical 2005" />{{rp|1419}} Practical interstellar exploration was framed as a combined problem of propulsion theory and navigation theory, rather than as a propulsion-only problem.<ref name="Minami FP Practical 2005" />{{rp|1419; 1420}} A 2009 propulsion survey framed one motivation for field propulsion research in operational terms, arguing that if field interactions could reduce effective gravitational and inertial resistance, rocket thrust and propellant requirements for Earth-to-orbit flight would be substantially reduced.<ref name="Czysz Bruno FP 2009" />{{rp|439}}

Minami's navigation theory framing was situated within similar [[Extra dimensions|extra-dimensional]] theory discussions, including [[Kaluza-Klein theory]], [[supergravity|supergravity theory]], [[superstring theory]], [[M theory]], and [[D-brane]]-related superstring theory, as part of the paper's conceptual background for interstellar navigation.<ref name="Minami FP Practical 2005" />{{rp|1420}} Minami and Musha reviewed proposals outlined further below, including [[vacuum polarization]] (a quantum effect in which strong fields produce short-lived virtual particle pairs), engineered spacetime curvature, and zero-point-field interactions; they distinguish between two field propulsion concepts: one framed in terms of general relativity and one in terms of quantum field theory.<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|215-216,219}}

Vacuum-fluctuation phenomena such as the [[Casimir effect]] have been measured in many precision experiments and are reviewed extensively in the mainstream literature.<ref name="Klimchitskaya et al Casimir 2009" />{{rp|1827, 1829-1830}} However, attempts to obtain net thrust or a gravity coupling from static electromagnetic configurations (often framed as "electrogravitic" effects) have not produced reproducible anomalous forces in controlled tests.<ref name="Tajmar SciRep 2024 gravity-EM steady fields" />{{rp|2,15}}<ref name="Tajmar AIAA 2004 Biefeld-Brown corona wind" />{{rp|315,318}}

==Types== A wide range of propulsion methods have been proposed or demonstrated that fit within broad definitions of field propulsion. This taxonomy reflects how late twentieth-century contractor reports and program reviews organized the subject, and how later surveys distinguish environment-coupled momentum exchange from more speculative proposals.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|26}}<ref name="Gilland NIAC Plasma 2011" />{{rp|1-2}} One group comprises environment-coupled systems that utilize their surroundings to produce thrust, including solar sails, magnetic sails, and, with certain restrictions, electrodynamic tethers, which use the solar wind or ambient magnetic fields to generate thrust. In one example design, a magnetic sail uses a loop of superconducting cable to create a magnetic field that deflects solar wind plasma and imparts momentum to the attached spacecraft.<ref name="Gilland NIAC Plasma 2011" />{{rp|1-2}}<ref name="ZubrinAndrews1991" />{{rp|197}}

A more speculative class invokes direct interactions with a structured vacuum or with spacetime geometry, proposing thrust without expelling mass, an idea discussed in general relativity and quantum field theory literature but not empirically validated.<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|215,218-219}} The sections below follow the broader historical literature usage outlined above, treating propellantless environment-coupled systems as the core cases while also retaining related beamed-energy concepts, terrestrial field interactions, and more speculative proposals where the source literature grouped them under the same field-propulsion umbrella.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|25-26,I-2}}<ref name="NASA FP small 2024-03-17" /><ref name="Gilland NIAC Plasma 2011" />{{rp|1-2}}

===Demonstrated=== Various field propulsion approaches and systems have achieved experimental validation, flight heritage, or sustained engineering development.

====Environment-coupled momentum exchange==== [[File:Light Sail Probe to Alpha Centauri (26338959171).jpg|thumb|Rendering of an interstellar light sail craft.]] [[File:NASA magnetosphere plasma waves diagram.png|thumb|[[NASA Goddard Space Flight Center|NASA Goddard]] schematic of Earth's [[magnetosphere]] with regions of natural [[plasma waves]] (including [[Whistler (radio)|chorus]], [[Magnetosonic wave|magnetosonic]], [[Ultra low frequency|ultra-low frequency]] waves, and [[Plasmasphere|plasmaspheric hiss]]). Plasma-wave [[spacecraft propulsion|propulsion]] concepts propose to couple with such [[Plasma (physics)#Wave-particle interactions|wave-particle interactions]].]]

These systems generate thrust by exchanging momentum with external fields (magnetic, plasma, or photon), without expelling onboard reaction mass. Solar sails are a propellant-less propulsion method that produces thrust from [[Solar radiation pressure|solar photon pressure]], rather than by expelling reaction mass.<ref name="NASA FP small 2024-03-17" /><ref name="Johnson et al NASA 2013" />{{rp|4,5}} As with other environment coupled concepts, sail performance depends on local solar pressure: the [[interstellar probe]] concept uses a very close solar flyby to take advantage of "increased solar flux" and the resultant "increased solar photon pressure", and scaling to a 160,000 m2 sail would require advances in sail materials, deployment, and [[Spacecraft attitude control|attitude control]] systems.<ref name="Johnson et al NASA 2013" />{{rp|4}}

Sailcraft engineering couples ultra-light structures to stringent pointing and thermal constraints.<ref name="McInnes PhilTransA 2003" />{{rp|2990, 2995}}<ref name="Forward lightsails 1984" />{{rp|188}} Once deployed, thrust is almost normal to the sail, so small attitude changes steer the thrust vector.<ref name="McInnes PhilTransA 2003" />{{rp|2990-2991}} Performance evolves with materials science and control: lower [[areal density]] (mass per unit sail area) directly increases acceleration,<ref name="Forward lightsails 1984" />{{rp|188}} and by tilting the sail the small continuous thrust can be steered for precise trajectory shaping.<ref name="McInnes PhilTransA 2003" />{{rp|2990}} Square and heliogyro designs use [[thin film]] sails on deployable booms; reliable deployment of large, low-mass structures and thin films is a key challenge.<ref name="McInnes PhilTransA 2003" />{{rp|2991,3004-3005}} Typical sail films have reflective front coats and high-emissivity back coats; wrinkling and billowing reduce efficiency.<ref name="McInnes PhilTransA 2003" />{{rp|2993-2995}} Forward (''[[Journal of Spacecraft and Rockets]],'' 1984) outlined a proposed method of how solar-system-based laser systems and a roughly 1,000 km light-focusing [[Fresnel lens]] system could propel thin-film sails to ~0.11% of the speed of light, enabling an unmanned flyby of [[Alpha Centauri]] in approximately 40 years.<ref name="Forward lightsails 1984" />{{rp|187,193}} In Forward's proposal, a two-stage sail system in which a massive ring sail reflects laser light back onto a detached payload sail, enabling the unmanned spacecraft to rendezvous and brake within the Alpha Centauri system.<ref name="Forward lightsails 1984" />{{rp|193-194}}

Analyses of magnetic sail concepts indicate thrust arises from deflecting the solar wind around a spacecraft-supported magnetic field, with performance set by the distance at which solar-wind pressure balances the sail's magnetic pressure; larger effective magnetic cross-sections increase momentum transfer but require large-radius, high-current superconducting coils.<ref name="ZubrinAndrews1991" />{{rp|197-200}} Mission studies of magnetic sails show that they can perform [[Heliocentric orbit|heliocentric]] transfers between [[circular orbits]] by using the solar wind for outbound acceleration and inbound braking.<ref name="ZubrinAndrews1991" />{{rp|197-199}} Magsails have also been proposed for interstellar missions, where interaction with the interstellar medium provides propellantless terminal deceleration into a destination solar system.<ref name="ZubrinAndrews1991" />{{rp|201-203}} Key engineering challenges include the mass and size of the superconducting loop and the constraints imposed by achievable superconducting currents and magnetic fields.<ref name="ZubrinAndrews1991" />{{rp|197-199}} The design tradeoffs emphasize achieving a large effective magnetic cross-section for the superconducting loop while keeping its mass low.<ref name="ZubrinAndrews1991" />{{rp|199}} Magnetospheric plasma propulsion (M2P2) is a NIAC proposal by Robert Winglee, in which plasma injection inflates a magnetic bubble that couples with the solar wind. It is considered a variant of magnetic sails.<ref name="Winglee M2P2 NASA" /><ref name="Wired M2P2 1999-08-18" />

The most studied examples are electrodynamic tethers (EDT), which generate Lorentz-force-based drag or thrust by coupling a long current-carrying conductor to a planetary magnetic field, thereby exchanging momentum with a planetary magnetosphere or [[ionosphere]] to enable propellantless drag or thrust in suitable environments (e.g., low Earth orbit), and fall under broad definitions of field propulsion due to their use of external fields for momentum exchange.<ref name="Gilland NIAC Plasma 2011" />{{rp|1}}<ref name="Cutler Carroll Tethers 1992" />{{rp|136-138}}<ref name="Cosmo Lorenzini SR 1997" />{{rp|153-155, 83-84}} In operation, a conductive tether moving through a planetary magnetic field experiences a motional [[electromotive force]], a voltage induced by its motion through the field; closing the circuit through the ambient ionosphere allows current to flow, and the resulting Lorentz force can provide either drag (for [[deorbit]]) or, with external power injection, thrust along specific orbital geometries.<ref name="Cosmo Lorenzini SR 1997" />{{rp|137,146-147}} As open systems, they conserve momentum by reaction with the ambient plasma and magnetic field.<ref name="Cosmo Lorenzini SR 1997" />{{rp|188, 153-155}} Electrodynamic tethers have been deployed in several [[space tether missions]], including the TSS-1, TSS-1R, and Plasma Motor Generator (PMG) experiments.<ref name="Cosmo Lorenzini SR 1997" />{{rp|153-155, 83-84}} Electrodynamic tethers can also generate electrical power at the expense of [[orbital energy]].<ref name="Cosmo Lorenzini SR 1997" />{{rp|151}}

Related electrostatic sail concepts also entered in-space technology-demonstration phases in the 2020s. NASA's small-spacecraft propulsion survey described the [[electric sail]] and the closely related plasma brake as relatively immature environment-coupled propulsion technologies, and noted that AuroraSat-1, launched on May 5, 2022, served as a technology demonstration mission for a Plasma Brake module.<ref name="NASA SOA propulsion 2024" /> In 2025, [[Aalto University]] in [[Finland]] reported the launch of Foresail-1p carrying a Plasma Brake experiment intended to enable the first-ever space measurements of Coulomb drag, in which a charged tether interacts with surrounding plasma to change a satellite's orbit.<ref name="NASA SOA propulsion 2024" /><ref name="Aalto Foresail-1p 2025" />

===Development and testing=== These are concepts under active engineering development or testing that adapt field-based acceleration or coupling principles for new operational regimes. As in the historical survey literature discussed above, this section includes some systems that fall outside the narrower propellantless-only sense of field propulsion, especially externally powered concepts and terrestrial field-matter coupling applications.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|I-2,25-26}}<ref name="NASA FP small 2024-03-17" />

====Beamed-energy and externally powered thrust==== [[File:Laser broom (artistic).jpg|thumb|A rendering of a [[laser broom]] concept. Beamed-energy systems proposed for debris removal share technology heritage with laser propulsion concepts.]] Microwave electrothermal thrusters use microwave energy, potentially externally supplied, to heat a fluid propellant. When powered externally, it falls under beamed-energy propulsion with mass acceleration via directed fields. [[Laser propulsion|Laser ablation propulsion]] uses pulsed laser energy to ablate onboard material into a plasma jet; although it expels mass, the energy source is external, placing it within beamed-energy propulsion approaches. Photonic laser thrusters are a photon-pressure system that relies on externally beamed lasers instead of sunlight.

[[Leik Myrabo]]'s beamed-energy Lightcraft program, spanning several decades, employed a projected-power, combined-cycle MHD system designed to reconfigure across multiple flight regimes.<ref name="Czysz Bruno FP 2009" />{{rp|193}} Czysz and Bruno also highlighted the concept's very low onboard propellant requirement, writing that it had "the least onboard propellants of any system".<ref name="Czysz Bruno FP 2009" />{{rp|193}} Myrabo's architecture was described as scalable by siting the projector on Earth, in orbit, or on the Moon, explicitly noting propulsion implications for geosynchronous orbit, the Moon, and nearby planetary/moon systems.<ref name="Czysz Bruno FP 2009" />{{rp|193}} Research has been limited to laboratory testing and subscale atmospheric Lightcraft demonstrations, with orbital proposals remaining unflown.

====Field-interaction in atmosphere or dense media==== [[File:JR-Maglev-MLX01-2.jpg|thumb|[[SCMaglev]] during a test run on the [[Yamanashi Prefecture|Yamanashi]] test track in Japan, November 2005.]]

Broad historical treatments of field propulsion placed terrestrial field-matter coupling systems alongside space-oriented concepts, even though these operate in dense media rather than as propellantless spacecraft.<ref name="Myrabo NASA JPL Beam/Field Concepts 1983" />{{rp|IX-14-15,IX-33,XIII-1-3}}<ref name="Takezawa et al Yamato1 Jime 1994" /><ref name="Gilmore Barrett 2015" />{{rp|2}} Although not presently in wide use for space, there exist proven terrestrial examples of field propulsion in which electromagnetic fields act upon a conducting medium such as seawater or plasma for propulsion, known collectively as magnetohydrodynamics (MHD). MHD is similar in operation to electric motors, however, rather than using moving parts or metal conductors, fluid or plasma conductors are employed. The EMS-1 and more recently the ''Yamato 1''<ref name="Akagi et al 1994-05-27" />{{rp|562}} are examples of such electromagnetic field-propulsion systems, first described in 1994.<ref name="Meng 5333444" />

Electrohydrodynamics (EHD) is another method where electrically charged fluids are accelerated for propulsion and flow control; laboratory and flight demonstrations include [[Ion-propelled aircraft|ion devices]] driven by [[corona discharge]], in which a strong electric field ionizes surrounding air to create a thrust-producing flow of charged particles.<ref name="Gilmore Barrett 2015" />{{rp|2}}<ref name="Nature 2018 aeroplane et al" />{{rp|532-535}} Magnetohydrodynamic interaction concepts extending magnetohydrodynamics (MHD) to space plasma propose generating thrust by exchanging momentum with ambient charged particles via Lorentz-force coupling. If the interacting plasma is external (e.g., ionospheric or solar wind), the system qualifies as field propulsion.<ref name="Czysz Bruno FP 2009" />{{rp|450-451}}

[[Magnetic levitation]] (maglev) ground transport systems are another terrestrial example of propulsion via externally generated fields: maglev employs magnetic forces to lift, guide, and propel a vehicle over a guideway, with propulsion typically provided by a [[linear motor]] whose traveling magnetic field pulls or pushes the vehicle along the track.<ref name="BTS TSAR 2001 Maglev" /><ref name="FRA Maglev Deployment Program 1998" />{{rp|2342}}

===Proposed and theorized=== These concepts are discussed in aerospace literature primarily as theoretical or exploratory frameworks rather than operational propulsion technologies.

====Field propulsion based on physical structure of space==== [[File:Spacetime lattice analogy.svg|thumb|Representation of [[Earth]] curving surrounding [[spacetime]] in [[general relativity]], illustrating how [[gravitational field]]s are treated as distortions of the underlying [[manifold|spacetime structure]]. Some proposed field propulsion concepts aim to couple with such structural changes.]]

Minami and Musha frame field propulsion at the physics frontier as interaction with a "substantial physical structure" of space, drawing on general relativity at [[macroscopic]] scales and quantum field theory at microscopic scales.<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|215-216}} In Minami and Musha's framing, propulsive force arises from interaction with a physical structure of space instead of from expelling reaction mass.<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|216-217}} As one candidate concept, Minami treated space as "an elastic body like rubber" and argued that space curvature could create an "acceleration field," stating that "a space drive is produced in the region of curved space."<ref name="Minami FP JBIS 2003" />{{rp|352}}<ref name="Musha FP" />{{rp|20-21}} A 1979 NASA technical memorandum outlined a speculative field resonance propulsion concept that hypothesized thrust from a resonance between coherent pulsed [[electromagnetic field]] waveforms and gravitational waveforms associated with spacetime metrics, framed as potentially enabling galactic travel without prohibitive travel times.<ref name="Holt NASA 1979" />{{rp|ii}}

Minami and Musha distinguish between two field propulsion concepts: one framed in terms of general relativity and one in terms of quantum field theory.<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|215-220}} According to quantum field theory and [[quantum electrodynamics]], the [[quantum vacuum]] is modeled as a nonradiating electromagnetic background, existing in a zero-point state, the minimum energy allowed by the theory.<ref name="Musha FP" />{{rp|24-25}} It was proposed that applying this to an [[dielectric|electrically insulating]] material could, via Lorentz forces on charges bound within the material, affect its inertia and thereby create acceleration without internal mechanical stress.<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|216-219}} Potential concepts studied by NASA and other parties have included vacuum polarization, engineered spacetime curvature, and zero-point-field interactions; none have been experimentally validated, and all face unresolved consistency issues with momentum conservation.<ref name="Millis BPPP NASA 1998" />{{rp|2}}

==Ongoing missions and research== Several foundational ideas in field propulsion, from Kepler's 1610 vision of "sails adapted to the heavenly breezes", have since been realized in demonstrated spaceflight systems.{{efn|Kepler's 1610 passage is cited as a historical anticipation of photon-sail ideas, not as a technical description of modern solar sailing. The later sources document in-space solar-sail demonstrations, including IKAROS and LightSail missions.<ref name="Kepler Quotes" /><ref name="Rosen Kepler" />{{rp|39}}<ref name="PS FP 2015-06-09" /><ref name="PS FP 2020 LightSail2" /><ref name="NASA Chronicle 2018" />}} Meanwhile, concepts once unproven now fly in space, and research continues on the remaining unproven options.{{efn|This distinction separates systems with in-space demonstration or flight heritage from propulsion concepts that remain exploratory. ACS3 and Foresail-1p support the continuing demonstration side, while NIAC plasma-wave studies and NASA's Breakthrough Propulsion Physics work support the continuing research and evaluation of unproven concepts.<ref name="NASA ACS3 what-is" /><ref name="NASA ACS3 deploy 2024" /><ref name="Aalto Foresail-1p 2025" /><ref name="Gilland NIAC Plasma 2011" />{{rp|1,25-26}}<ref name="Millis BPPP NASA 1998" />{{rp|1-2}}}}

==Demonstrated and proposed systems== The following table summarizes first demonstrated usage, operational domain, and development status for field propulsion subtypes discussed in this article, ranging from systems with flight heritage to theoretical proposals.

{| class="wikitable sortable" style="width:100%;" |+ First demonstrated usage by field propulsion subtype |- ! Propulsion subtype ! Domain ! First demonstrated usage ! Date ! Vehicle / mission ! Status ! Remarks |- | [[Magnetic levitation|Magnetic levitation]] (maglev) | Ground | First commercial maglev people-mover scheduled for passenger operation | 1984 | [[Air-Rail Link#Maglev|Birmingham Airport Maglev]] people mover (Birmingham Airport ↔ Birmingham International railway station) | Operational (1984–1995) | ''[[New Scientist]]'' described in 1984 the world's first commercial maglev, scheduled for operation in April 1984, and noted linear induction motor propulsion.<ref name="NS Birmingham Maglev 1984" /> Terrestrial; propulsion via linear motor traveling magnetic field along guideway.<ref name="BTS TSAR 2001 Maglev" /><ref name="NYT maglev 1991-03-23" />{{rp|9}} |- | [[Electrodynamic tether]] | Space | TSS-1 deployment from Space Shuttle | 1992 | [[Space tether missions#TSS-1 mission|TSS-1]] ([[NASA]]) | Demonstrated | Environment-coupled; exchanges momentum with planetary magnetosphere. TSS-1R (1996, [[STS-75]]) and PMG also demonstrated.<ref name="Cosmo Lorenzini SR 1997" />{{rp|153–155, 83–84}}<ref name="NASA tether 1999-03-13" /> |- | [[Magnetohydrodynamics|Magnetohydrodynamic]] (MHD) ship drive | Marine | Superconducting MHD thruster propelled experimental ship in harbor trials | 1992 | ''[[Yamato 1]]'' ([[Kobe Harbor]], Japan) | Demonstrated | Terrestrial; electromagnetic field propulsion using seawater as conducting medium.<ref name="Takezawa et al Yamato1 Jime 1994" />{{rp|402}}<ref name="Seattle Times Yamato1 1992-07-20" /> |- | [[Lightcraft]] (beamed-energy) | Atmospheric | Subscale atmospheric flight demonstrations | 1997 | Lightcraft ([[Leik Myrabo]]) | Demonstrated (subscale atmospheric) | First flight in 1997.<ref name="Lightcraft AIAA 1998" />{{rp|1}} Beamed-energy combined-cycle MHD; orbital proposals remain unflown.<ref name="Czysz Bruno FP 2009" />{{rp|193}} |- | [[Solar sail]] | Space | First deep-space solar sail demonstration; confirmed photon acceleration | 2010 | [[IKAROS]] ([[JAXA]]) | Operational | Environment-coupled; propellantless. [[LightSail|LightSail 1]] (2015) and [[LightSail#LightSail 2|LightSail 2]] (2019) followed.<ref name="JAXA IKAROS 2010" /><ref name="PS FP 2015-06-09" /><ref name="PS FP 2020 LightSail2" /> NASA's [[Solar sail#Advanced Composite Solar Sail System (ACS3)|ACS3]] (2024) demonstrated composite-boom sail deployment.<ref name="NASA ACS3 what-is" /><ref name="NASA ACS3 deploy 2024" /> |- | [[Electrohydrodynamics|Electrohydrodynamic]] (EHD) aircraft | Atmospheric | Solid-state propulsion aircraft flight | 2018 | [[MIT EAD Airframe Version 2|MIT EHD aircraft]] (Xu et al.) | Demonstrated | Atmospheric; corona-discharge-driven ionic wind propulsion with no moving parts.<ref name="Nature 2018 aeroplane et al" />{{rp|532-535}}<ref name="Gilmore Barrett 2015" />{{rp|2}} |- | Ambient plasma-wave propulsion | Space | – | data-sort-value="9999" | – | – | Proposed | NIAC Phase I study; technically immature.<ref name="Gilland NIAC Plasma 2011" />{{rp|1,25-26}} |- | [[Beam-powered propulsion#Laser propulsion|Laser lightsail]] (interstellar) | Space | – | data-sort-value="9999" | – | – | Proposed | Laser-pushed thin-film sail to ~0.11c proposed by [[Robert L. Forward|Forward]] (1984).<ref name="Forward lightsails 1984" />{{rp|187,193}} |- | [[Magnetic sail|Magnetospheric plasma propulsion]] (M2P2) | Space | – | data-sort-value="9999" | – | – | Proposed | Plasma-inflated magnetic bubble couples with solar wind; NIAC proposal by Winglee; variant of magnetic sails.<ref name="Winglee M2P2 NASA" /><ref name="Wired M2P2 1999-08-18" /> |- | [[Magnetic sail]] | Space | – | data-sort-value="9999" | – | – | Proposed | Environment-coupled; superconducting loop deflects solar wind. Proposed by Andrews and [[Robert Zubrin|Zubrin]].<ref name="ZubrinAndrews1991" />{{rp|197}} |- | Vacuum / spacetime coupling | Space | – | data-sort-value="9999" | – | – | Theoretical | No experimental validation; unresolved consistency issues with momentum conservation.<ref name="Millis BPPP NASA 1998" />{{rp|2}}<ref name="Minami Musha Field Acta Astronautica 2012" />{{rp|215-216,219}} |}

==See also== {{Sister project links}}

* {{anl|Bussard ramjet}} * {{anl|Emerging technologies}} * [[History of aviation]] * [[History of rockets]] * [[History of spaceflight]] * {{anl|New Millennium Program}} * {{anl|Non-rocket spacelaunch}} * {{anl|Spacecraft electric propulsion}} * [[Timeline of aviation]] * [[Timeline of rocket and missile technology]] * [[Timeline of spaceflight]]

==Notes== {{notelist}}

==References== {{US government sources}} <references>

<ref name="Aalto Foresail-1p 2025">{{Cite web |date=2025-12-01 |title=Finland's Foresail-1p science satellite successfully launched into space |url=https://www.aalto.fi/en/news/finlands-foresail-1p-science-satellite-successfully-launched-into-space |website=[[Aalto University]] |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20260314023902/https://www.aalto.fi/en/news/finlands-foresail-1p-science-satellite-successfully-launched-into-space |archive-date=2026-03-14}}</ref>

<ref name="Akagi et al 1994-05-27">{{cite journal|url=http://www.ovaltech.ca/pdfss/mhddesign.pdf|title=Optimal Design of Thruster System for Superconducting Electromagnetic Propulsion Ship| first1=Shinsuke |last1=Akagi|first2=Kikuo|last2=Fujita |first3=Kazuo |last3=Soga|journal=Proceedings of the 5th International Marine Design Conference |url-status=dead|date=1994-05-27|access-date=2026-02-11|archive-url=https://web.archive.org/web/20210930060643/http://www.ovaltech.ca/pdfss/mhddesign.pdf|archive-date=2021-09-30}}</ref>

<ref name="Alcubierre Warp 1994">{{cite journal | last=Alcubierre | first=Miguel | author-link=Miguel Alcubierre | title=The warp drive: hyper‑fast travel within general relativity | journal=Classical and Quantum Gravity | volume=11 | issue=5 | pages=L73–L77 | year=1994 | doi=10.1088/0264-9381/11/5/001 | arxiv=gr-qc/0009013 }}</ref>

<ref name="Ash 1977">{{Cite book |editor-last=Ash |editor-first=Brian |title=The Visual Encyclopedia of Science Fiction |date=1977 |publisher=[[Harmony Books]] |location=New York |isbn=978-0-517-53175-4|url=https://archive.org/details/visualencycloped00ashb}}</ref>

<ref name="BBC Greenglow 2016-03-23">{{Cite web|date=2016-03-23|title=Project Greenglow and the battle with gravity|url=https://www.bbc.com/news/magazine-35861334|url-status=live|website=[[BBC]]|archive-url=https://web.archive.org/web/20160323010453/https://www.bbc.com/news/magazine-35861334|archive-date=2016-03-23}}</ref>

<ref name="BTS TSAR 2001 Maglev">{{cite web|title=Transportation Statistics Annual Report 2001: Chapter 3, Transportation System Condition and Extent|website=[[Bureau of Transportation Statistics]]|publisher=[[United States Department of Transportation]]|url=https://www.bts.gov/archive/publications/transportation_statistics_annual_report/2001/chapter_03|access-date=2026-02-16}}</ref>

<ref name="Burroughs Barsoom">{{Cite web|title=A Princess of Mars|date=1912|last=Burroughs |first=Edgar Rice|author-link=Edgar Rice Burroughs |url=https://www.gutenberg.org/cache/epub/62/pg62.txt|url-status=live|website=[[Project Gutenberg]]|archive-url=https://web.archive.org/web/20260215055355/https://www.gutenberg.org/cache/epub/62/pg62.txt|archive-date=2026-02-15}}</ref>

<ref name="Campbell Instrumentation Dean 1960">{{Cite journal |last=Campbell |first=John W. |author-link=John W. Campbell |title=Instrumentation for the Dean Device |journal=[[Analog Science Fiction and Fact|Astounding/Analog Science Fact & Fiction]] |volume=LXVI |issue=3 |date=November 1960 |pages=95–99 |url=https://www.luminist.org/archives/SF/AN.htm |archive-url=https://web.archive.org/web/20230420221225/https://s3.us-west-1.wasabisys.com/luminist/SF/AN/AN_1960_11.pdf |archive-date=2023-04-20}}</ref>

<ref name="Campbell Report Dean 1960">{{Cite journal |last=Campbell |first=John W. |author-link=John W. Campbell |title=Report on the Dean Drive |journal=[[Analog Science Fiction and Fact|Astounding/Analog Science Fact & Fiction]] |volume=LXVI |issue=1 |date=September 1960 |pages=4–7 |url=https://www.luminist.org/archives/SF/AN.htm |archive-url=https://web.archive.org/web/20230420221735/https://s3.us-west-1.wasabisys.com/luminist/SF/AN/AN_1960_09.pdf |archive-date=2023-04-20}}</ref>

<ref name="Campbell Space Drive 1960">{{Cite journal |last=Campbell |first=John W. |author-link=John W. Campbell |title=The Space Drive Problem |journal=[[Analog Science Fiction and Fact|Astounding/Analog Science Fact & Fiction]] |volume=LXV |issue=4 |date=June 1960 |pages=83–106|url=https://www.luminist.org/archives/SF/AN.htm|archive-url=https://web.archive.org/web/20230420220958/https://s3.us-west-1.wasabisys.com/luminist/SF/AN/AN_1960_06.pdf|archive-date=2023-04-20}}</ref>

<ref name="Chicago Tribune FP 1980-01-29">{{Cite news|date=1980-01-29|title=A farout idea: Tunneling through space-time barrier|last1=Preston|first1=Marylynn|url=https://www.newspapers.com/image/386953911/?terms=%22field%20propulsion%22|url-status=live|website=[[Chicago Tribune]]|quote='One of the most important things to me', Holt says, 'is to help break down the inhibiting mental attitude that space-time field interactions will remain in the realm of science fiction for hundreds of years.'|pages=15,18|archive-url=https://web.archive.org/web/20260216180122/https://www.newspapers.com/image/386953911/?terms=%22field%20propulsion%22|archive-date=2026-02-16|access-date=2026-02-16}}</ref>

<ref name="Choueiri FP 2004">{{cite journal |last=Choueiri |first=Edgar Y. |author-link=Edgar Choueiri|title=A Critical History of Electric Propulsion: The First Fifty Years (1906-1956) |journal=[[Journal of Propulsion and Power]] |volume=20 |issue=2 |pages=193-203 |date=2004 |url=https://mae.princeton.edu/sites/g/files/toruqf7696/files/ChoueiriHistJPC04.pdf|archive-url=https://web.archive.org/web/20251004004258/https://mae.princeton.edu/sites/g/files/toruqf7696/files/ChoueiriHistJPC04.pdf|archive-date=2025-10-04|quote=The reader will soon note a measure of the vagaries of that evolution: while the earliest thoughts and experiments related to EP are almost all about electrostatic propulsion, the first laboratory electric thruster was electrothermal and the first electric thruster to ever fly in space was of the pulsed (mostly electromagnetic) plasma type.}}</ref>

<ref name="Cosmo Lorenzini SR 1997">{{cite report | title=Tethers in Space Handbook | edition=3rd | editor-last1=Cosmo | editor-first1=Mario L. | editor-last2=Lorenzini | editor-first2=Enrico C. | publisher=[[NASA Marshall Space Flight Center]]; [[Smithsonian Astrophysical Observatory]] | date=December 1997 | url=https://ntrs.nasa.gov/api/citations/19980018321/downloads/19980018321.pdf | access-date=2025-12-01 | archive-url=https://web.archive.org/web/20220228050645/https://ntrs.nasa.gov/api/citations/19980018321/downloads/19980018321.pdf | archive-date=2022-02-28}}</ref>

<ref name="Cutler Carroll Tethers 1992">{{cite book | last1=Cutler | first1=Andrew H. | last2=Carroll | first2=Joseph A. | year=1992 | chapter=Tethers | editor1-last=Towell | editor1-first=Donald D. | editor2-last=Franklin | editor2-first=Sharon | editor3-last=Shoji | editor3-first=James M. | title=Space Resources. Volume 2: Energy, Power, and Transport | series=NASA Special Publication | number=SP-509 | publisher=[[NASA Johnson Space Center]] | location=Houston, TX | pages=136–145 | url=https://ntrs.nasa.gov/citations/19930007726 | id=NTRS 19930007726 | access-date=2025-12-01 | archive-url=https://web.archive.org/web/20250419211449/https://ntrs.nasa.gov/api/citations/19930007726/downloads/19930007726.pdf | archive-date=2025-04-19 | quote=Electrically conducting tethers will couple to the Earth’s magnetic field. In low Earth orbit (LEO) there is sufficient plasma density to allow large currents to flow through the tether and close the loop efficiently through the plasma. The interaction between the current and the magnetic field produces a force that propels the tether... without expending propellant.}}</ref>

<ref name="Czysz Bruno FP 2009">{{cite book |editor1-last=Czysz |editor1-first=Paul A. |editor2-last=Bruno |editor2-first=Claudio |title=Future Spacecraft Propulsion Systems: Enabling Technologies for Space Exploration |edition=2nd |publisher=[[Springer Publishing]] |location=Berlin; Heidelberg |year=2009 |isbn=978-3-540-88813-0}}</ref>

<ref name="Dröscher Hauser">{{cite web |last=Dröscher |first=Walter |last2=Hauser |first2=Jochem |title=Introduction to Physics, Astrophysics and Cosmology of Gravity-Like Fields |publisher=HPCC-Space GmbH |date=November 2015|url=https://gravitymodification.com/wp-content/uploads/2015/08/PrimerPhysicsGravityExcerpt1.pdf |format=PDF |access-date=2026-02-12|archive-url=https://web.archive.org/web/20161116165206/https://gravitymodification.com/wp-content/uploads/2015/08/PrimerPhysicsGravityExcerpt1.pdf|archive-date=2016-11-16|quote=According to this novel approach, apart from leading to a change in the [[wiktionary:Weltbild|Weltbild]] of physics by extending the general theory of relativity, gravitational engineering may eventually become a technological reality and lead to a novel era of spaceflight, i.e., propellantless propulsion. As a further consequence for physics, this theoretical view would force major extensions of both the standard model of cosmology and particle physics by providing a mechanism for the existence of dark matter and dark energy as well as novel fundamental particles.}}</ref>

<ref name="DS9 Companion 2000">{{Cite book |last1=Erdmann |first1=Terry J. |last2=Block |first2=Paula M. |title=[[Star Trek: Deep Space Nine Companion]] |date=2000 |publisher=[[Pocket Books]] |isbn=0-671-50106-2|pages=236–237}}</ref>

<ref name="FP Conference page 2001">{{Cite web|date=2001-07-21|title=First International Field Propulsion Meeting, University of Sussex, Brighton, England. January 20st-22nd 2001|url=http://workshop.cwc.net/|url-status=dead|quote=This WORKSHOP was called as the European response to the establishment of the NASA 'Breakthrough Propulsion Physics' workshops, & is open to all International participants, on a Global basis. Following recent coverage in the Public and scientific media, with regard to emerging experimental and engineering results in the field of 'Propellentless propulsion', and theoretical and experimental work on the 'Electrogravitics' hypothesis, it was decided that a European focus for this area was needed, external to NASA and the United States, and also International in character.|website=[[Society of British Aerospace Companies]]|archive-url=https://web.archive.org/web/20010721131905/http://workshop.cwc.net/|archive-date=2001-07-21}}</ref>

<ref name="FP Globe 1958-05-31">{{Cite web|date=1958-05-31|title=Aviation Men Told Airpower War Deterrent|last1=Riley|first1=Arthur A.|url=https://www.newspapers.com/image/433482982/?match=1&terms=%22field%20propulsion%22|url-status=live|website=[[Boston Daily Globe]]|quote=Putt prophesized that there would be 'undreamed-of' strides in the field of propulsion with vehicles boosted away from the earth with million-pound rocket engines which could continue with photo or ion field-type propulsion, and this should cover our solar system.|archive-url=https://web.archive.org/web/20260214014454/https://www.newspapers.com/image/433482982/?match=1&terms=%22field%20propulsion%22|archive-date=2026-02-14|page=6}}</ref>

<ref name="Forward lightsails 1984">{{cite journal | last = Forward | first = Robert L. | author-link=Robert L. Forward|title = Roundtrip interstellar travel using laser-pushed lightsails | journal =[[Journal of Spacecraft and Rockets]] | volume = 21 | issue = 2 | pages = 187–195 | date = March–April 1984 | doi = 10.2514/3.8632 | bibcode = 1984JSpRo..21..187F | issn = 0022-4650 | url = https://arc.aiaa.org/doi/10.2514/3.8632 | archive-url = https://web.archive.org/web/20131221025144/https://path-2.narod.ru/design/base_e/rit-1.pdf | archive-date = 2013-12-21| url-access = subscription }}</ref>

<ref name="FRA Maglev Deployment Program 1998">{{cite web|title=Magnetic Levitation Transportation Technology Deployment Program (Final Rule)|website=[[Federal Railroad Administration]]|publisher=[[United States Department of Transportation]]|url=https://railroads.dot.gov/elibrary/magnetic-levitation-transportation-technology-deployment-program|access-date=2026-02-16|archive-url=https://web.archive.org/web/20210424154954/https://railroads.dot.gov/elibrary/magnetic-levitation-transportation-technology-deployment-program|archive-date=2021-04-24|pages=2342-2348}}</ref>

<ref name="Franklin FP Levitt 1957">{{cite report |chapter=Satellites and Travel in the Future |title=Ten Steps into Space: A Series of Lectures Sponsored by The Franklin Institute, March-May, 1958, in Philadelphia |last1=Levitt|first1=Israel Monroe|series=Journal of the Franklin Institute |number=Monograph No. 6 |publisher=[[The Franklin Institute]]|website=[[Washington Headquarters Services]] |location=Philadelphia, Pennsylvania |date=December 1958 |url=https://www.esd.whs.mil/Portals/54/Documents/FOID/Reading%20Room/Other/15F1747_DOC_01_Ten_Steps_into_Space_Monograpgh_6_ADB193716.pdf |access-date=2026-02-17|pages=179-202|archive-url=https://web.archive.org/web/20190309204848/https://www.esd.whs.mil/Portals/54/Documents/FOID/Reading%20Room/Other/15F1747_DOC_01_Ten_Steps_into_Space_Monograpgh_6_ADB193716.pdf|archive-date=2019-03-09}}</ref>

<ref name="Franklin FP Ritchey 1957">{{cite report |chapter=Rocket Fuels - Liquid and Solid| title=Ten Steps into Space: A Series of Lectures Sponsored by The Franklin Institute, March-May, 1958, in Philadelphia |last1=Ritchey|first1=H.W.|series=Journal of the Franklin Institute |number=Monograph No. 6 |quote=There might be another way of doing it if we can get around this requirement for an exhaust jet by the use of fields. We might be able to do this in a touch more simple and direct way by breaking the laws of Newton, or at least bending them to our will, to the point where we don't have to squirt a working fluid backwards to make a force. To show you that it could be done, in Fig. 11 I have drawn a picture of the Earth and its magnetic field, with a flying saucer. This flying saucer has a coil of wire around the outside of it and it sends a terrifically high current through that coil of wire and generates a current sheet. Some of the Earth's vertical components in the magnetic field are trapped by that current sheet, creating a force that tends to lift the saucer away from the Earth.|publisher=[[The Franklin Institute]]|website=[[Washington Headquarters Services]] |location=Philadelphia, Pennsylvania |date=December 1958 |url=https://www.esd.whs.mil/Portals/54/Documents/FOID/Reading%20Room/Other/15F1747_DOC_01_Ten_Steps_into_Space_Monograpgh_6_ADB193716.pdf |access-date=2026-02-17|pages=46-47|archive-url=https://web.archive.org/web/20190309204848/https://www.esd.whs.mil/Portals/54/Documents/FOID/Reading%20Room/Other/15F1747_DOC_01_Ten_Steps_into_Space_Monograpgh_6_ADB193716.pdf|archive-date=2019-03-09}}</ref>

<ref name="Friedman Solar sailing 1978">{{cite journal |last=Friedman |first=Louis |title=Solar sailing: The concept made realistic |journal=[[Acta Astronautica]]|volume=5 |issue=5-6 |year=1978 |pages=297-308 |doi=10.1016/0094-5765(78)90033-8 | url=https://ntrs.nasa.gov/citations/19780038658 |archive-url=https://web.archive.org/web/20260313165301/https://ntrs.nasa.gov/citations/19780038658 | archive-date=2026-03-13}}</ref>

<ref name="Garner Solar Sail Summary 1999">{{cite conference |last1=Garner |first1=Charles E. |last2=Diedrich |first2=Benjamin |last3=Leipold |first3=Manfred |title=A Summary of Solar Sail Technology and Demonstration Status |conference=35th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit |date=1999 |url=https://ntrs.nasa.gov/api/citations/20000059207/downloads/20000059207.pdf|archive-url=https://web.archive.org/web/20240818074755/https://ntrs.nasa.gov/api/citations/20000059207/downloads/20000059207.pdf|archive-date=2024-08-18}}</ref>

<ref name="Getty Ritchey">{{Cite web|date=|title=IBM 7090|url=https://www.gettyimages.co.uk/detail/news-photo/american-businessman-dr-hw-ritchey-vice-president-of-the-news-photo/1457958980|url-status=live|website=[[Getty Images]]|quote=American businessman Dr HW Ritchey, Vice President of the Thiokol Chemical Corporation and Technical Director of the company's Rocket Division, stands pointing at a chart above an IBM 7090 mainframe computer, across the top of the chart it reads, 'a network of computer centers for design, data acquisition, and proof of performance' below which it reads 'Thiokol Chemical Corporation' as well as a list of Thiokol's requirements and results, at an US Air Force facility for the launch of ICBM (intercontinental ballistic missile), United States, November 1959.|archive-url=https://web.archive.org/web/20260304044430/https://www.gettyimages.co.uk/detail/news-photo/american-businessman-dr-hw-ritchey-vice-president-of-the-news-photo/1457958980|archive-date=2026-03-04}}</ref>

<ref name="Gilland NIAC Plasma 2011">{{cite report| last1 = Gilland| first1 = James H.| last2 = Williams| first2 = George J.| title = The Potential for Ambient Plasma Wave Propulsion| publisher = [[NASA Institute for Advanced Concepts]] (NIAC)| date = 2011| url = https://www.nasa.gov/wp-content/uploads/2017/07/01-niac_2011_phasei_gilland_thepotentialforambientplasma_tagged.pdf| access-date = 2025-06-06| archive-url = https://web.archive.org/web/20240612082051/https://www.nasa.gov/wp-content/uploads/2017/07/01-niac_2011_phasei_gilland_thepotentialforambientplasma_tagged.pdf| archive-date=2024-06-12}}</ref>

<ref name="Gilmore Barrett 2015">{{Cite journal |last1=Gilmore|first1=Christopher K. | last2=Barrett | first2=Steven R. H. | title=Electrohydrodynamic thrust density using positive corona-induced ionic winds for in-atmosphere propulsion | journal=[[Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences]] | volume=471 | issue=2175 | article-number=20140912 | date=2015 | doi=10.1098/rspa.2014.0912 | url=https://royalsocietypublishing.org/doi/10.1098/rspa.2014.0912| url-status=live | archive-url=https://web.archive.org/web/20191025024354/https://royalsocietypublishing.org/doi/10.1098/rspa.2014.0912 | archive-date=2019-10-25| url-access=subscription }}</ref>

<ref name="Goswami 1985">{{cite book|first1=Amit |last1=Goswami|first2=Maggie |last2=Goswami|title=The Cosmic Dancers: Exploring the Science of Science Fiction|url=https://books.google.com/books?id=3YnWAAAAMAAJ|access-date=2026-03-04|date=July 1985|publisher=[[McGraw-Hill]]|isbn=978-0-07-023867-1|page=23}}</ref>

<ref name="Holt NASA 1979">{{cite report |last=Holt |first=Alan C. |title=Field Resonance Propulsion Concept |type=NASA Technical Memorandum |number=NASA-TM-80961 |institution=[[National Aeronautics and Space Administration]], [[Lyndon B. Johnson Space Center]] |location=Houston, Texas |date=August 1979 |url=https://ntrs.nasa.gov/api/citations/19800010907/downloads/19800010907.pdf |id=JSC-16073; NTIS N80-19184; NTRS 19800010907 |access-date=2026-02-13|archive-url=https://web.archive.org/web/20201208160021/https://ntrs.nasa.gov/api/citations/19800010907/downloads/19800010907.pdf|archive-date=2020-12-08}}</ref>

<ref name="Holt FP 1980 NTRS">{{cite conference |last=Holt |first=Alan C. |title=Prospects for a breakthrough in field-dependent 'propulsion' |website=[[NASA STI Program]] |date=1980-06-01 |url=https://ntrs.nasa.gov/citations/19800054809 |access-date=2026-02-20 |type=Conference paper |id=NASA NTRS 19800054809 |conference=Joint Propulsion Conference (AIAA/SAE/ASME), Hartford, Connecticut, June 30 to July 2, 1980}}</ref>

<ref name="Huntsville FP 1980-10-27">{{Cite news|date=1980-10-27|title=Magnetism Suggested To Launch Space Probes|last1=Dooling|first1=Dave|url=https://www.newspapers.com/image/1184409937/?match=1&terms=%22field%20propulsion%22|url-status=live|website=[[The Huntsville Times]]|page=4|archive-url=https://web.archive.org/web/20260216190835/https://www.newspapers.com/image/1184409937/?match=1&terms=%22field%20propulsion%22|archive-date=2026-02-16|access-date=2026-02-16}}</ref>

<ref name="JAXA IKAROS 2010">{{Cite web|date=2010-07-09|title=Small Solar Power Sail Demonstrator 'IKAROS' Confirmation of Photon Acceleration|url=https://global.jaxa.jp/press/2010/07/20100709_ikaros_e.html|url-status=live|website=[[Japan Aerospace Exploration Agency]]|archive-url=https://web.archive.org/web/20250404103214/https://global.jaxa.jp/press/2010/07/20100709_ikaros_e.html|archive-date=2025-04-04}}</ref>

<ref name="Johnson et al NASA 2013">{{cite conference |last1=Johnson |first1=Les |author2-link=Grover Swartzlander |last2=Swartzlander |first2=Grover A. |last3=Artusio-Glimpse |first3=Alexandra |title=An Overview of Solar Sail Propulsion within NASA |conference=International Symposium on Solar Sailing |website=[[NASA]]|location=Glasgow, United Kingdom |date=2013-06-11 |url=https://ntrs.nasa.gov/api/citations/20140000641/downloads/20140000641.pdf|access-date=2026-02-10|archive-url=https://web.archive.org/web/20231115022758/https://ntrs.nasa.gov/api/citations/20140000641/downloads/20140000641.pdf|archive-date=2023-11-15|quote=JAXA began a series of deployment test flights in 2004, leading to the successful flight of the Interplanetary Kite-craft Accelerated by Radiation Of the Sun (IKAROS) in 2010. The IKAROS is the first deep-space demonstration of solar sailing. The IKAROS verified solar radiation pressure effects on the sail and performing in-flight guidance and navigation techniques using the solar sail.}}</ref>

<ref name="Kepler Quotes">{{Cite web|date=August 1610|title=Science Quotes by Johannes Kepler|last1= Kepler |first1= Johannes |authorlink1=Johannes Kepler|url=https://todayinsci.com/K/Kepler_Johannes/KeplerJohannes-Quotations.htm|url-status=live|archive-url=https://web.archive.org/web/20260301120956/https://todayinsci.com/K/Kepler_Johannes/KeplerJohannes-Quotations.htm|archive-date=2026-03-01}}</ref>

<ref name="Kim et al Physics WS">{{cite book |last1=Ho-Kim |first1=Quang |last2=Kumar |first2=Narendra |last3=Lam |first3=Harry C. S. |title=Invitation to Contemporary Physics |year=2004 |publisher=[[World Scientific]] |page=19 |isbn=978-981-238-303-7|url-status=dead|url=http://dspace.rri.res.in/bitstream/2289/6139/1/Invitation%20to%20contep%20Phys.pdf|archive-url=https://archive.org/details/invitationtocont00hoki|archive-date=2025-12-05}}</ref>

<ref name="Klimchitskaya et al Casimir 2009">{{cite journal |last1=Klimchitskaya |first1=G. L. |last2=Mohideen |first2=U. |last3=Mostepanenko |first3=V. M. |title=The Casimir force between real materials: Experiment and theory |journal=[[Reviews of Modern Physics]] |volume=81 |issue=4 |pages=1827–1885 |date=2009-12-21 |doi=10.1103/RevModPhys.81.1827 |url=https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.81.1827 |archive-url=https://web.archive.org/web/20210828135809/https://journals.aps.org/rmp/pdf/10.1103/RevModPhys.81.1827 |archive-date=2021-08-28|arxiv=0902.4022 }}</ref>

<ref name="Koch Discovery Spore 2018">{{cite conference|last1=Koch|first1=Evelyn|title=Weird Fungi in Space – The Mycelium Network as the Other in Star Trek: Discovery|book-title=Fantastic Beasts, Monstrous Cyborgs, Aliens and Other Spectres: Alterity in Fantasy and Science Fiction|publisher=[[University of Freiburg|Albert-Ludwigs-Universität Freiburg]]|location=Freiburg, Germany|date=19–20 October 2018|url=https://www.academia.edu/38394751|archive-url=https://web.archive.org/web/20250525230116/https://www.researchgate.net/publication/331224496_Weird_Fungi_in_Space_-_The_Mycelium_Network_as_the_Other_in_Star_Trek_Discovery|archive-date=2025-05-25|url-status=live|quote=a semi-fictitious fungal species called ''prototaxites stellaviatori'' which by means of their invisible mycelium network enable spaceships to jump through the universe and even to parallel universes, a method referred to as ‘organic propulsion system' in the series.}}</ref>

<ref name="Lebedev FP 1900">{{Cite conference |last=Lebedev|first=P. |author-link=Pyotr Lebedev |title=Les forces de Maxwell-Bartoli dues à la pression de la lumière|trans-title=The Maxwell–Bartoli forces due to the pressure of light|language=fr |book-title=Congrès international de physique, Paris 1900 |publisher=Gauthier-Villars |location=Paris| date=1900 |volume=2|pages=133-140|url=https://gallica.bnf.fr/ark:/12148/bpt6k9813485f.texteImage |website=[[Bibliothèque nationale de France]] |access-date=2026-03-05|archive-url=https://web.archive.org/web/20250421184413/https://gallica.bnf.fr/ark:/12148/bpt6k9813485f.texteImage|archive-date=2025-04-21|url-status=live}}</ref>

<ref name="Lightcraft AIAA 1998">{{cite conference |last1=Myrabo |first1=Leik N. |author-link1=Leik Myrabo|last2=Messitt |first2=Donald G. |last3=Mead|first3=Franklin B., Jr. |title=Ground and Flight Tests of a Laser Propelled Vehicle |conference=36th AIAA Aerospace Sciences Meeting and Exhibit |location=Reno, Nevada |date=1998 |publisher=[[American Institute of Aeronautics and Astronautics]] |series=AIAA Paper |number=98-1001 |doi=10.2514/6.1998-1001 |url=https://ayuba.fr/pdf/myrabo1998a.pdf |url-status=live |archive-url=https://web.archive.org/web/20250804223650/https://ayuba.fr/pdf/myrabo1998a.pdf |archive-date=2025-08-04}}</ref>

<ref name="Matloff Photon Sail 2004">{{cite report |last=Matloff |first=Gregory L. |title=Photon Sail History, Engineering, and Mission Analysis |publisher=[[NASA]] |website=[[NASA Technical Reports Server]] |date=2004-09-01 |url=https://ntrs.nasa.gov/api/citations/20050199476/downloads/20050199476.pdf |archive-url=https://web.archive.org/web/20260312154014/https://ntrs.nasa.gov/api/citations/20050199476/downloads/20050199476.pdf |archive-date=2026-03-12 |url-status=live}}</ref>

<ref name="McInnes PhilTransA 2003">{{cite journal | last=McInnes | first=Colin R. | title=Solar sailing: mission applications and engineering challenges | journal=[[Philosophical Transactions of the Royal Society A]]| volume=361| pages=2989–3008 | date=2003 | issue=1813 | doi=10.1098/rsta.2003.1280 | url=https://eprints.gla.ac.uk/28/1/Roy_SocA.pdf | archive-url=https://web.archive.org/web/20160304205450/https://eprints.gla.ac.uk/28/1/Roy_SocA.pdf | archive-date=2016-03-04 | location=[[University of Glasgow]] | pmid=14667309 | bibcode=2003RSPTA.361.2989M }}</ref>

<ref name="Meng 5333444">{{Cite patent|country=US|number=5333444|pubdate=1994-08-02|title=Superconducting electromagnetic thruster|assign1=[[United States Secretary of the Navy]]|inventor1-last=Meng|inventor1-first=James C. S.}}</ref>

<ref name="Miller Sail Gizmodo 2014-03-13">{{Cite web|date=2014-03-13|title=How the Solar Sail Could Fuel Interplanetary Travel|last1=Miller|first1=Ron|url=https://gizmodo.com/how-the-solar-sail-might-one-day-fuel-interplanetary-tr-1535937811|url-status=live|archive-url=https://web.archive.org/web/20221001080651/https://gizmodo.com/how-the-solar-sail-might-one-day-fuel-interplanetary-tr-1535937811|archive-date=2022-10-01}}</ref>

<ref name="Millis 1996-07-16">{{cite report |last=Millis |first=Marc G. |title=The Challenge to Create the Space Drive |type=NASA Technical Memorandum |number=107289 |institution=[[NASA Lewis Research Center]] |location=Cleveland, Ohio |date=1996-07-16 |url=https://ntrs.nasa.gov/api/citations/19960048672/downloads/19960048672.pdf |id=19960048672 |language=en |access-date=2026-02-12|archive-url=https://web.archive.org/web/20210716191800/https://ntrs.nasa.gov/api/citations/19960048672/downloads/19960048672.pdf|archive-date=2021-07-16|quote=A typical expectation is that the induced forces would just act between the vehicle's field-inducing device and the rest of the vehicle, like blowing in your own sails, or trying to move a car by pushing on it from the inside. In such cases all the forces act internally and there would be no net motion of the vehicle. For reference, this issue can be called the net external force requirement. The net external force requirement is closely related to conservation of momentum. Conservation of momentum requires that the momentum imparted to the vehicle must be equal and opposite to the momentum imparted to a reaction mass. In the case of a field drive, there is no obvious reaction mass for the vehicle to push against.}}</ref>

<ref name="Millis BPPP NASA 1998">{{cite report| last=Millis| first=Marc G.| title=NASA Breakthrough Propulsion Physics Program| publisher=[[NASA Lewis Research Center]]| date=June 1998| series=NASA Technical Memorandum| number=NASA/TM–1998–208400| location=Cleveland, OH| url=https://ntrs.nasa.gov/api/citations/19980201240/downloads/19980201240.pdf| archive-url=https://web.archive.org/web/20210623050310/https://ntrs.nasa.gov/api/citations/19980201240/downloads/19980201240.pdf| archive-date=2021-06-23| access-date=2025-06-13 | language=en}}</ref>{{rp|1}}

<ref name="Millis Coupling Gravity EM Spacetime 1995">{{cite report |last=Millis |first=Marc G. |title=Coupling Gravity, Electromagnetism and Space-Time for Space Propulsion Breakthroughs |institution=[[NASA Lewis Research Center]] |url=https://ntrs.nasa.gov/citations/19950002760 |access-date=2026-02-20 |id=NASA NTRS 19950002760 |archive-url=https://web.archive.org/web/20250414002513/https://ntrs.nasa.gov/api/citations/19950002760/downloads/19950002760.pdf |archive-date=2025-04-14 |pages=93,94-95,95 |quote=For field propulsion, the fields themselves must act as the reaction mass.}}</ref>

<ref name="Minami FP JBIS 2003">{{cite journal |last=Minami |first=Yoshinari |title=An Introduction to Concepts of Field Propulsion |journal=[[Journal of the British Interplanetary Society]] |volume=56 |issue=9 |date=September 2003 |pages=350–359 |url=https://www.researchgate.net/publication/259659196_An_Introduction_to_Concepts_of_Field_Propulsion |access-date=2026-02-20}}</ref>

<ref name="Minami FP Practical 2005">{{cite conference |last=Minami |first=Yoshinari |title=A Perspective of Practical Interstellar Exploration: Using Field Propulsion and Hyper-Space Navigation Theory |book-title=[[AIP Conference Proceedings]] |date=February 13–17, 2005 |pages=1419–1428 |location=Albuquerque, New Mexico |type=conference paper |conference=[[Space Technology and Applications International Forum]] |url=https://pubs.aip.org/aip/acp/article-abstract/746/1/1419/605761/A-Perspective-of-Practical-Interstellar |archive-url=https://web.archive.org/web/20260221012510/https://www.researchgate.net/profile/Yoshinari-Minami/publication/228741646_A_Perspective_of_Practical_Interstellar_Exploration-_Using_Field_Propulsion_and_Hyper-Space_Navigation_Theory/links/5572264308aeacff1ffac9b5/A-Perspective-of-Practical-Interstellar-Exploration-Using-Field-Propulsion-and-Hyper-Space-Navigation-Theory.pdf |archive-date=2026-02-21 |doi=10.1063/1.1867273|url-access=subscription }}</ref>

<ref name="Minami Musha Field Acta Astronautica 2012">{{cite journal| last1=Minami| first1=Yoshinari| last2=Musha| first2=Takaaki| title=Field propulsion systems for space travel| journal=[[Acta Astronautica]]| volume=81| issue=1| pages=59–66| date=January 2012| publisher=[[Elsevier]]| doi=10.1016/j.actaastro.2012.02.027| url=https://www.academia.edu/53605673| archive-url=https://web.archive.org/web/20260303194810/https://www.academia.edu/53605673/Field_propulsion_systems_for_space_travel | archive-date=2026-03-03 | access-date=2025-09-17| issn=0094-5765| language=en|quote=Field propulsion systems were proposed by many researchers to overcome the speed limit of the conventional space propulsion system. Field propulsion system can be propelled without mass expulsion; its propulsion principle can induce a propulsive force (i.e., thrust) that arises from the interaction of the substantial physical structure.}}</ref>{{rp|1-2}}

<ref name="Musha FP">{{cite book|last1=Musha|first1=Takaaki|title=Field Propulsion System for Space Travel: Physics of Non-Conventional Propulsion Methods for Interstellar Travel|date=15 February 2018|publisher=[[Bentham Science Publishers]]|isbn=978-1-60805-566-1|pages=20–37}}</ref>

<ref name="Myrabo NASA JPL Beam/Field Concepts 1983">{{cite report | title=Advanced Beamed-Energy and Field Propulsion Concepts | last1=Myrabo |first1=Leik N. | author1-link =Leik Myrabo | publisher=[[Braddock Dunn & McDonald|BDM Corporation]] for the [[California Institute of Technology]] and [[Jet Propulsion Laboratory]] | date=May 31, 1983 | type=Contractor Report | series=[[NASA]] Contractor Report Series | number=NASA-CR-176108 | location=McLean, Virginia | url=https://ntrs.nasa.gov/api/citations/19850024873/downloads/19850024873.pdf | archive-url =https://web.archive.org/web/20211214024616/https://ntrs.nasa.gov/api/citations/19850024873/downloads/19850024873.pdf | archive-date=2021-12-14 | id=BDM/W-83-225-TR; NAS 1.26:176108; Accession 85N33186 | access-date=2026-02-19}}</ref>{{rp|25-26,32,36,406,456}}

<ref name="NASA ACS3 deploy 2024">{{Cite web |date=2024-08-29 |title=NASA Composite Booms Deploy, Mission Sets Sail in Space |url=https://www.nasa.gov/blogs/smallsatellites/2024/08/29/nasa-composite-booms-deploy-mission-sets-sail-in-space/ |website=[[NASA]] |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20260110034257/https://www.nasa.gov/blogs/smallsatellites/2024/08/29/nasa-composite-booms-deploy-mission-sets-sail-in-space/ |archive-date=2026-01-10}}</ref>

<ref name="NASA ACS3 what-is">{{Cite web |title=Advanced Composite Solar Sail System: Using Sunlight to Power Deep Space Exploration (ACS3) |url=https://www.nasa.gov/smallspacecraft/what-is-acs3/ |website=[[NASA]] |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20260205090722/https://www.nasa.gov/smallspacecraft/what-is-acs3/ |archive-date=2026-02-05}}</ref>

<ref name="NASA Chronicle 2018">{{cite book|url=https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf|title=Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016|page=2|last1=Siddiqi|first1=Asif A.|lccn=2017059404|isbn=978-1-62683-042-4|publisher=NASA History Program Office|edition=second|year=2018|id=SP2018-4041|series=The NASA history series|location=Washington, DC}}</ref>

<ref name="NASA History of Rockets">{{Cite web|title= Brief History of Rockets|url=https://www.grc.nasa.gov/www/k-12/TRC/Rockets/history_of_rockets.html|url-status=live|website=[[NASA John H. Glenn Research Center at Lewis Field]]|archive-url=https://web.archive.org/web/20250930224445/https://www.grc.nasa.gov/www/k-12/TRC/Rockets/history_of_rockets.html|archive-date=2025-09-30}}</ref>

<ref name="NASA FP small 2024-03-17">{{Cite web|date=2024-03-17|title=State-of-the-Art of Small Spacecraft Technology|url=https://www.nasa.gov/smallsat-institute/sst-soa/in-space_propulsion/|url-status=live|website=[[NASA]]|archive-url=https://web.archive.org/web/20250827105154/https://www.nasa.gov/smallsat-institute/sst-soa/in-space_propulsion/|archive-date=2025-08-27|quote=Propellant-less propulsion systems generate thrust via interaction with the surrounding environment (e.g., solar photon pressure, planetary magnetic fields, solar wind and ionospheric plasma pressures, and planetary atmospheres). By contrast, chemical and electric propulsion systems generate thrust by expulsion of reaction mass (i.e., propellant). Four propellant-less propulsion technologies have undergone in-space demonstrations to date, including solar sails, tethers, electric sails (and plasma brakes), and aerodynamic drag devices.}}</ref>

<ref name="NASA SOA propulsion 2024">{{Cite web |date=2024-03-17 |title=4.0 In-Space Propulsion |url=https://www.nasa.gov/smallsat-institute/sst-soa/in-space_propulsion/ |website=[[NASA]] |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20260203134733/https://www.nasa.gov/smallsat-institute/sst-soa/in-space_propulsion/ |archive-date=2026-02-03}}</ref>

<ref name="NASA tether 1999-03-13">{{Cite web|date=1999-03-13|title=#25c. The Space Tether Experiment|url=https://pwg.gsfc.nasa.gov/Education/wtether.html|url-status=live|website=[[NASA|NASA's Polar, Wind, and Geotail projects]]|archive-url=https://web.archive.org/web/20020831061040/https://pwg.gsfc.nasa.gov/Education/wtether.html|archive-date=2002-08-31}}</ref>

<ref name="Nature 2018 aeroplane et al">{{cite journal| last1=Xu| first1=Haofeng| last2=He| first2=Yiou | last3=Strobel| first3=Kieran L.| last4=Gilmore | first4=Christopher K. | last5=Kelley | first5=Sean P. | last6=Hennick | first6=Cooper C. | last7=Sebastian | first7=Thomas | last8=Woolston | first8=Mark R. | last9=Perreault | first9=David J. | last10=Barrett | first10=Steven R. H. | title=Flight of an aeroplane with solid-state propulsion | journal=[[Nature (journal)|Nature]] | date=2018-11-21 | volume=563 | pages=532-535 | doi=10.1038/s41586-018-0707-9 | url=https://www.nature.com/articles/s41586-018-0707-9 | access-date=2025-11-18 | archive-url=https://web.archive.org/web/20251118174323/https://www.nature.com/articles/s41586-018-0707-9 | archive-date=2025-11-18| url-access=subscription }}</ref>

<ref name="Navascués FP 1928">{{cite book |title=The Illustrated Official Journal (Patents)|date=1930-01-08 |publisher=[[The Stationery Office|H.M. Stationery Office]] |location=London |url=https://www.google.com/books/edition/Illustrated_official_journal_patents/2gGRoFdcjaMC?hl=en&gbpv=0|quote=...producing translatory motion of machine by current reaction with earth's field. Propulsion is caused by cutting with a closed conducting turn the earth's magnetic flux...|page=7231}}</ref>

<ref name="NASM Rynin">{{Cite web|title=Nikolai Alekseevich Rynin|url=https://pioneersofflight.si.edu/content/nikolai-alekseevich-rynin-0|website=[[National Air and Space Museum]]|quote=An engineer, Rynin took an early interest in advocating space exploration. In 1928 he published Interplanetary Communications, the first encyclopedia on the history and theory of rocket technology and spaceflight.|access-date=2026-03-06|archive-url=https://web.archive.org/web/20260120080639/https://pioneersofflight.si.edu/content/nikolai-alekseevich-rynin-0|archive-date=2026-01-20}}</ref>

<ref name="Nowlan Armageddon">{{Cite web|title=Armageddon--2419 A.D.|date=1928|last=Nowlan |first=Philip Francis|author-link=Philip Francis Nowlan |url=https://www.gutenberg.org/files/32530/32530-h/32530-h.htm|url-status=live|website=[[Project Gutenberg]]|archive-url=https://web.archive.org/web/20260205120550/https://www.gutenberg.org/files/32530/32530-h/32530-h.htm|archive-date=2026-02-05}}</ref>

<ref name="NS Birmingham Maglev 1984">{{Cite news|date=1984-03-15|title=Birmingham maglev off to flying start|last=Hamer|first=M.|publisher=[[New Scientist]]|website=[[National Academies of Sciences, Engineering, and Medicine]]|url=https://trid.trb.org/View/203071|access-date=2026-03-03|archive-url=https://web.archive.org/web/20201125172258/https://trid.trb.org/View/203071|archive-date=2020-11-25}}</ref>

<ref name="NYT maglev 1991-03-23">{{Cite news|date=1991-03-23|title=U.S. investing in magnetic trains|last1=Browne|first1=Malcolm W.|url=https://www.newspapers.com/image/625691079/?match=1&terms=%22field%20propulsion%22 |website=[[New York Times]], [[Sacramento Bee]]|page=9}}</ref>

<ref name="Observer FP 2001-01-07">{{Cite news|date=2001-01-07|title=Scientists switch to warp drive as sci-fi energy source is tapped|last1=McKie|first1=Robin|author-link1=Robin McKie|url=https://www.newspapers.com/image/258306118/?match=1&terms=%22field%20propulsion%22|url-status=live|website=[[The Observer]]|archive-url=https://web.archive.org/web/20260216202742/https://www.newspapers.com/image/258306118/?match=1&terms=%22field%20propulsion%22|archive-date=2026-02-16|page=13|access-date=2026-02-16}}</ref>

<ref name="Planetary Alcubierre 2014">{{Cite web |date=2014-09-09 |title=Miguel Alcubierre, Inventor of Warp Drive? |url=https://www.planetary.org/planetary-radio/0909-miguel-alcubierre-inventor-of-warp-drive |url-status=live |website=[[The Planetary Society]] |archive-url=https://web.archive.org/web/20250118074942/https://www.planetary.org/planetary-radio/0909-miguel-alcubierre-inventor-of-warp-drive |archive-date=2025-01-18|quote=Inspired by Star Trek, distinguished physicist Miguel Alcubierre developed the general relativity-based model for warp drive 20 years ago.}}</ref>

<ref name="Prucher 2007">{{Cite book |last=Prucher |first=Jeff |title=Brave New Words: The Oxford Dictionary of Science Fiction |date=2007 |publisher=[[Oxford University Press]] |isbn=978-0-19-530567-8 |url=https://archive.org/details/bravenewwordsoxf00pruc|page=167|quote=The television show Star Trek, which first aired in 1966, has probably had a greater effect on the English language than any other single science fiction creation, with the possible exception of George Orwell's Nineteen Eighty-Four}}</ref>

<ref name="PS FP 2015-06-09">{{Cite web|date=2015-06-09|title=LightSail Test Mission Declared Success; First Image Complete|last1=Davis|first1=Jason|url=https://www.planetary.org/articles/20150609-lightsail-test-mission-success|url-status=live|website=[[The Planetary Society]]|archive-url=https://web.archive.org/web/20200814171847/https://www.planetary.org/articles/20150609-lightsail-test-mission-success|archive-date=2020-08-14}}</ref>

<ref name="PS FP 2020 LightSail2">{{Cite web|date=2020|title=LightSail: Flight|url=https://www.planetary.org/sci-tech/lightsail|url-status=live|archive-url=https://web.archive.org/web/20200731051427/https://www.planetary.org/sci-tech/lightsail|archive-date=2020-07-31|quote=LightSail® is a crowdfunded project from The Planetary Society to demonstrate that solar sailing is a viable means of propulsion for CubeSats — small, standardized spacecraft that are part of a global effort to lower the cost of space exploration. Our LightSail 2 spacecraft, which launched on June 25, 2019 and reentered Earth's atmosphere on Nov. 17, 2022, used sunlight alone to change its orbit.}}</ref>

<ref name="Putt NASM">{{Cite web|title=LtGen. Donald L. Putt, USAF|url=https://airandspace.si.edu/support/wall-of-honor/ltgen-donald-l-putt-usaf|url-status=live|website=[[National Air and Space Museum]]|quote=Near the end of the war in Europe he was sent there to head up Air Corps Technical Intelligence and to evaluate captured scientific facilities in Germany. The most significant discovery was the Goering Institute at Braunschweig where he, in conjunction with Dr. von Karman and others, discovered supersonic wind tunnels, swept wing aircraft designs and many eminent scientists. Col. Putt headed up Operation Paperclip which brought very significant scientific equipment, documents and German aeronautical scientists to the United States.|archive-url=https://web.archive.org/web/20220506162105/https://airandspace.si.edu/support/wall-of-honor/ltgen-donald-l-putt-usaf|archive-date=2022-05-06}}</ref>

<ref name="Rosen Kepler">{{Cite book |last=Kepler |first=Johannes |author-link=Johannes Kepler |translator-last=Rosen |translator-first=Edward |title=Kepler's Conversation with Galileo's Sidereal Messenger |series=The Sources of Science, No. 5|publisher=Johnson Reprint Corporation |location=New York |year=1965 |page=39}}</ref>

<ref name="Rynin Vol 1 1928">{{cite book|last=Rynin |first=Nikolai A. |author-link=Nikolai Rynin|title=Interplanetary Flight and Communication: Dreams, Legends, and Early Fantasies|series=Interplanetary Flight and Communication |volume=1 |issue=1|orig-date=1928 |date=1971|publisher=Israel Program for Scientific Translations|location=Jerusalem|id=NASA TT F-640|url=https://archive.org/stream/nasa_techdoc_19710013614/19710013614_djvu.txt|access-date=2026-03-06}}</ref>

<ref name="Rynin Vol 8 1932">{{cite book|last=Rynin |first=Nikolai A. |author-link=Nikolai Rynin|title=Interplanetary Flight and Communication: Theory of Space Flight|series=Interplanetary Flight and Communication |volume=3 |issue=8|orig-date=1932 |date=1971|translator=R. Hardin|publisher=Israel Program for Scientific Translations|location=Jerusalem|id=NASA TT F-647|url=https://archive.org/stream/nasa_techdoc_19720015159/19720015159_djvu.txt|access-date=2026-03-06}}</ref>

<ref name="Seattle Times Yamato1 1992-07-20">{{Cite web|date=1992-07-20|title=Engineering: May The Force Be With You|last=Nickerson|first=Colin |website=[[The Seattle Times]]|url=https://archive.seattletimes.com/archive/19920720/1503104/engineering----may-the-force-be-with-you}}</ref>

<ref name="SFE Antigravity">{{Cite web|title=Antigravity|url=https://sf-encyclopedia.com/entry/antigravity|url-status=live|website=[[The Encyclopedia of Science Fiction]]|archive-url=https://web.archive.org/web/20260203083851/https://sf-encyclopedia.com/entry/antigravity|archive-date=2026-02-03}}</ref>

<ref name="SFE Apergy">{{Cite web|title= Apergy |url=https://sf-encyclopedia.com/entry/apergy|url-status=live|website=[[The Encyclopedia of Science Fiction]]|archive-url=https://web.archive.org/web/20260227121944/https://sf-encyclopedia.com/entry/apergy|archive-date=2026-02-27}}</ref>

<ref name="SFE Force Field">{{Cite web|title=Force Field |url=https://sf-encyclopedia.com/entry/force_field|url-status=live|website=[[The Encyclopedia of Science Fiction]]|archive-url=https://web.archive.org/web/20250718111215/https://sf-encyclopedia.com/entry/force_field|archive-date=2025-07-18}}</ref>

<ref name="SFE Hyperspace">{{Cite web|title=Hyperspace|url=https://sf-encyclopedia.com/entry/hyperspace|url-status=live|website=[[The Encyclopedia of Science Fiction]]|archive-url=https://web.archive.org/web/20251016190924/https://sf-encyclopedia.com/entry/hyperspace|archive-date=2025-10-16}}</ref>

<ref name="SFE Solar Wind">{{Cite web|title=Solar Wind|url=https://sf-encyclopedia.com/entry/solar_wind|url-status=live|website=[[The Encyclopedia of Science Fiction]]|archive-url=https://web.archive.org/web/20250713205806/https://sf-encyclopedia.com/entry/solar_wind|archive-date=2025-07-13}}</ref>

<ref name="SFE Space Warp">{{Cite web|title=Space Warp|url=https://sf-encyclopedia.com/entry/space_warp|url-status=live|website=[[The Encyclopedia of Science Fiction]]|archive-url=https://web.archive.org/web/20250802155609/https://sf-encyclopedia.com/entry/space_warp|archive-date=2025-08-02}}</ref>

<ref name="SFE Spindizzy">{{Cite web|title=Spindizzy|url=https://sf-encyclopedia.com/entry/Spindizzy|url-status=live|website=[[The Encyclopedia of Science Fiction]]|archive-url=https://web.archive.org/web/20251126112631/https://sf-encyclopedia.com/entry/spindizzy|archive-date=2025-11-26}}</ref>

<ref name="SFE Tractor Beam">{{Cite web|title=Tractor Beam|url=https://sf-encyclopedia.com/entry/tractor_beam|url-status=live|website=[[The Encyclopedia of Science Fiction]]|archive-url=https://web.archive.org/web/20260116130525/https://sf-encyclopedia.com/entry/tractor_beam|archive-date=2026-01-16}}</ref>

<ref name="SFF 1990s Timeline">{{Cite web |title=Our History: The 1990s |url=https://www.spacefrontier.org/copy-of-2000s|website=[[Space Frontier Foundation]] |archive-url=https://web.archive.org/web/20260118190304/https://www.spacefrontier.org/copy-of-2000s |archive-date=2026-01-18|quote=The conference featured an awards ceremony recognizing the Clementine lunar probe team for their work on frontier-enabling technology and the producers of Star Trek: Deep Space Nine for an episode on solar sails, reflecting the Foundation’s appreciation for both technical innovation and cultural inspiration.}}</ref>

<ref name="Smithsonian FP 2021-01-27">{{Cite web|date=2021-01-27|title=Imagining Faster-Than-Light Travel|last=Weitekamp |first=Margaret A.|url=https://airandspace.si.edu/stories/editorial/imagining-faster-light-travel|url-status=live|website=[[National Air and Space Museum]]|archive-url=https://web.archive.org/web/20250716032310/https://airandspace.si.edu/stories/editorial/imagining-faster-light-travel|archive-date=2025-07-16}}</ref>

<ref name="Sutton Rockets 2017">{{cite book| last1=Sutton| first1=George P.| last2=Biblarz| first2=Oscar| title=Rocket Propulsion Elements| edition=9th| publisher=[[Wiley (publisher)|Wiley]]| year=2017| isbn=978-1-118-75365-1| url=https://ftp.idu.ac.id/wp-content/uploads/ebook/tdg/DESIGN%20SISTEM%20DAYA%20GERAK/Rocket%20Propulsion%20Elements.pdf| archive-url=https://web.archive.org/web/20220612011026/https://ftp.idu.ac.id/wp-content/uploads/ebook/tdg/DESIGN%20SISTEM%20DAYA%20GERAK/Rocket%20Propulsion%20Elements.pdf| archive-date=2022-06-12}}</ref>{{rp|33}}

<ref name="Takezawa et al Yamato1 Jime 1994">{{cite journal | last1=Takezawa |first1=Setsuo |last2=Tamama |first2=Hiroshi |last3=Sugawara |first3=Kazumi |last4=Sakai |first4=Hiroshi |last5=Matsuyama |first5=Chiaki |last6=Morita |first6=Hiroaki |last7=Suzuki |first7=Hiromi|last8=Ueyama|first8=Yoshihiro|title=Operation of the Thruster for Superconducting Electromagnetohydrodynamic Propulsion Ship “YAMATO1”|journal=Journal of the Marine Engineering Society in Japan|volume=29|issue=6|year=1994|pages=402–411|doi=10.5988/jime1966.29.402|url=https://www.jstage.jst.go.jp/article/jime1966/29/6/29_6_402/_article |quote=The Ship & Ocean Foundation set up a research and development committee for MHD ship propulsion in 1985 and started an extensive R & D studies, and to construct an experimental ship to demonstrate that a ship can really be propelled by MHD thrusters with all the necessary machinery and equipments on board. The experimental ship, named the YAMATO 1, was completed in the fall of 1991 and was actually propelled successfully by MHD thrusters in the summer of 1992 in KOBE harbour.}}</ref>

<ref name="Tajmar AIAA 2004 Biefeld-Brown corona wind">{{cite journal |last=Tajmar |first=M. |title=Biefeld-Brown Effect: Misinterpretation of Corona Wind Phenomena |journal=[[AIAA Journal]] |volume=42 |issue=2 |date=2012-05-02 |doi=10.2514/1.9095 |url=https://arc.aiaa.org/doi/10.2514/1.9095 |access-date=2025-12-15|url-access=subscription }}</ref>

<ref name="Tajmar SciRep 2024 gravity-EM steady fields">{{cite journal |last=Tajmar |first=M. |last2=Kößling |first2=M. |last3=Neunzig |first3=O. |title=In-depth experimental search for a coupling between gravity and electromagnetism with steady fields |journal=[[Scientific Reports]] |volume=14 |article-number=19427 |date=2024-08-21 |doi=10.1038/s41598-024-70286-w |url=https://www.nature.com/articles/s41598-024-70286-w |access-date=2025-12-15 |archive-date=2024-08-28 |archive-url=https://web.archive.org/web/20240828154507/https://www.nature.com/articles/s41598-024-70286-w.pdf|pmc=11339412 }}</ref>

<ref name="Telegraph FP 1990-04-19">{{Cite news|date=1990-04-19|title=Magnetic propulsion ship on the horizon|last1=Petty|first1=John|url=https://www.newspapers.com/image/751423945/?match=1&terms=%22field%20propulsion%22 |website=[[The Daily Telegraph]]|page=11}}</ref>

<ref name="Time FP 1956-04-09">{{Cite web|date=1956-04-09|title=Cinema: The New Pictures, Apr. 9, 1956|url=https://time.com/archive/6804514/cinema-the-new-pictures-apr-9-1956/|url-status=live|website=[[Time (magazine)|Time]]}}</ref>

<ref name="UPI FP 1964-01-03">{{Cite web|date=1964-01-03|title=Future City Transit May Be Really Rapid|url=https://www.newspapers.com/image/63109488/?match=1&terms=%22field%20propulsion%22|url-status=live|website=[[United Press International]], [[Bennington Banner]]|archive-url=https://web.archive.org/web/20260214220422/https://www.newspapers.com/image/63109488/?match=1&terms=%22field%20propulsion%22|archive-date=2026-02-14|quote=Further away but possibly the ultimate answer in moving large numbers of people in safety are compressed air propulsion and super conductor magnetic field propulsion. Super conductor magnetic field propulsion will need a major research project before it is feasible. But there has been a proposal for such a magnetic line linking Youngston, Ohio, with Pittsburgh.|page=9}}</ref>

<ref name="Winglee M2P2 NASA">{{Cite web|title=Prototyping of Mini-Magnetospheric Plasma Propulsion (M2P2)|last1=Winglee|first1=Robert|url=https://science.gsfc.nasa.gov/670/seminar/previous_lep/spring2002/Winglee_a.html|url-status=live|website=[[NASA|NASA Heliophysics Science Division]]|archive-url=https://web.archive.org/web/20210325162815/https://science.gsfc.nasa.gov/670/seminar/previous_lep/spring2002/Winglee_a.html|archive-date=2021-03-25}}</ref>

<ref name="Wired M2P2 1999-08-18">{{Cite web|date=1999-08-18|title=Plasma-Powered Trip to the Stars|url=https://www.wired.com/1999/08/plasma-powered-trip-to-the-stars/|url-status=live|website=[[Wired (magazine)|Wired]]|quote=Developed by a team at the University of Washington, the Mini-Magnetospheric Plasma Propulsion system, or M2P2, has a maximum speed of 180,000 miles per hour, or 4.3 million miles a day, about ten times the speed of a space shuttle. The brainchild of geophysicist Robert Winglee, the M2P2 system employs a huge plasma field around a satellite. The field catches solar wind, like an enormous electromagnetic sail.}}</ref>

<ref name="Zander FP 1924">{{Cite web|date=1924|title=Перелеты на другие планеты|trans-title=Flights to Other Planets|last1=Zander |first1=Friedrich |authorlink1=Friedrich Zander|lang=ru|url=https://ru.wikisource.org/wiki/Страница:Перелеты_на_другие_планеты_(Цандер,_1924).pdf/2|url-status=live|website=[[Wikisource]]|publisher=Техника и жизнь|number=13|archive-url=https://web.archive.org/web/20220905220954/https://ru.wikisource.org/wiki/%D0%A1%D1%82%D1%80%D0%B0%D0%BD%D0%B8%D1%86%D0%B0:%D0%9F%D0%B5%D1%80%D0%B5%D0%BB%D0%B5%D1%82%D1%8B_%D0%BD%D0%B0_%D0%B4%D1%80%D1%83%D0%B3%D0%B8%D0%B5_%D0%BF%D0%BB%D0%B0%D0%BD%D0%B5%D1%82%D1%8B_(%D0%A6%D0%B0%D0%BD%D0%B4%D0%B5%D1%80,_1924).pdf/2|archive-date=2022-09-05|quote=«…вероятно, выгоднее будет лететь при помощи зеркал или экранов из тончайших листов…» (translation: "it would probably be more advantageous to fly by means of mirrors or screens made of extremely thin sheets.")}}</ref>

<ref name="ZubrinAndrews1991">{{Cite journal |last1=Zubrin |first1=Robert M. |last2=Andrews |first2=Dana G. |date=March 1991 |title=Magnetic sails and interplanetary travel |url=https://arc.aiaa.org/doi/10.2514/3.26230 |journal=[[Journal of Spacecraft and Rockets]] |language=en |volume=28 |issue=2 |pages=197–203 |doi=10.2514/3.26230 |bibcode=1991JSpRo..28..197Z |issn=0022-4650|url-access=subscription }}</ref>{{Rp|location=Sec. VIII}}

</references>

[[Category:Aerospace engineering]] [[Category:Applied sciences]] [[Category:Astrodynamics]] [[Category:Celestial mechanics]] [[Category:Exploratory engineering]] [[Category:Field propulsion]] [[Category:Hypothetical technology]] [[Category:NASA programs]] [[Category:Propulsion]] [[Category:Spacecraft components]] [[Category:Spacecraft propulsion]] [[Category:Spacecraft design]] [[Category:Spaceflight]]