Editing Lightcraft (section)

{{Short description|Aerospace craft utilizing beam-powered propulsion}}
[[File:Lightcraft.jpg|thumb|300px|Lightcraft being propelled by laser]]
The '''Lightcraft''' is a [[spacecraft|space-]] or [[aircraft|air-]][[vehicle]] driven by [[beam-powered propulsion]], the energy source powering the craft being external. It was conceptualized by aerospace engineering professor [[Leik Myrabo]] at [[Rensselaer Polytechnic Institute]] in 1976,<ref name="Myrabo 1976">
{{cite journal
 | author = Myrabo, L.N.
 | author-link = Leik Myrabo
 | date = 1976
 | title = MHD propulsion by absorption of laser radiation
 | journal = Journal of Spacecraft and Rockets
 | volume = 13
 | issue = 8
 | url = http://ayuba.fr/pdf/myrabo1976.pdf
 | doi = 10.2514/3.27919
 | pages=466–472
 | bibcode = 1976JSpRo..13..466M
 }}
</ref> who developed the concept further with working prototypes,<ref name="Myrabo 1st test">{{cite conference
 |last1=Myrabo |first1=Leik N.
 |last2=Messitt |first2=Donald G.
 |last3=Mead Jr. |first3=Franklin B.
 |title=36th AIAA Aerospace Sciences Meeting and Exhibit
 |chapter=Ground and flight tests of a laser propelled vehicle
 |date=January 1998
 |conference=36th AIAA Aerospace Sciences Meeting and Exhibit
 |location=Reno, NV
 |book-title=AIAA-98-1001
 |chapter-url=http://ayuba.fr/pdf/myrabo1998a.pdf
 |doi=10.2514/6.1998-1001
}}</ref> funded in the 1980s by the [[Strategic Defense Initiative]] organization, and the decade after by the ''Advanced Concept Division'' of the [[United States Air Force|US Air Force]] [[Air Force Research Laboratory|AFRL]], [[NASA]]'s [[Marshall Space Flight Center|MFSC]] and the [[Lawrence Livermore National Laboratory]].<ref name="Popular Mechanics 1995">{{cite magazine
 |last1=Pope |first1=Gregory T.
 |title=Fly by microwaves
 |date=September 1995
 |magazine=Popular Mechanics
 |pages=44–45
 |url=http://ayuba.fr/pdf/popmech1995.pdf
 }}</ref><ref name="Wired">{{cite magazine
 |last1=Demerjian |first1=Ave
 |title=Laser-powered aircraft are the future of flight. Maybe 
 |date=20 February 2009
 |magazine=Wired
 |url=https://www.wired.com/2009/02/beamed-energy-i/
 |access-date=2018-04-05
}}</ref><ref name="PopSci">{{cite web
 |last1=Hsu |first1=Jeremy
 |title=Laser-Powered Lightcraft 'At the Cusp of Commercial Reality'
 |date=29 July 2009
 |website=Popular Science
 |url=http://www.popsci.com/military-aviation-amp-space/article/2009-07/high-powered-lightcraft-experiments-hint-future-space-travel
 |access-date=2018-04-05
}}</ref>

When a Lightcraft is in the atmosphere, air is used as the propellant material (reaction mass). In space, it would need to provide the propellant material from onboard tanks or from an [[ablation|ablative]] solid. By leaving the vehicle's power source on the ground and by using ambient atmosphere as a reaction mass for much of its ascent, a Lightcraft could potentially be capable of delivering a very large percentage of its launch mass to orbit as an [[Single-stage-to-orbit|SSTO]], a difficult task for [[Rocket engine#Terminology|chemical rocket]]s. As such, a Lightcraft is distinct from a [[solar sail]] because it is dependent on the expansion of [[reaction mass]] to accelerate rather than being accelerated by [[radiation pressure|light pressure]] alone. Within the atmosphere, the Lightcraft propulsion is dependent on the external laser power only, so propulsive power is not limited to that generated by usual on-board machinery (i.e. [[rocket]]s).<ref name="NewSpace 2010" />