Editing Beam-powered propulsion (section)

== Economics ==
The motivation to develop beam-powered propulsion systems comes from the economic advantages gained due to improved propulsion performance. In the case of beam-powered launch vehicles, better propulsion performance enables some combination of increased payload fraction, increased structural margins, and fewer stages. [[JASON (advisory group)|JASON]]'s 1977 study of laser propulsion,<ref>{{Cite journal|last1=Dyson|first1=Freeman|last2=Perkins|year=1977|title=JASON Laser Propulsion Study|url=http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA047901|journal=Stanford Research Institute|access-date=2016-12-08|archive-url=https://web.archive.org/web/20161220091342/http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA047901|archive-date=2016-12-20|url-status=dead}}</ref> authored by [[Freeman Dyson]], succinctly articulates the promise of beam-powered launch: <blockquote>''"Laser propulsion as an idea that may produce a revolution in space technology. A single laser facility on the ground can in theory launch single-stage vehicles into low or high earth orbit. The payload can be 20% or 30% of the vehicle take-off weight. It is far more economical in the use of mass and energy than chemical propulsion, and it is far more flexible in putting identical vehicles into a variety of orbits."''</blockquote>This promise was quantified in a 1978 Lockheed Study<ref>{{Cite journal|last=Jones|first=W.|year=1979|title=Final Report. Laser Rocket System Analysis.|url=https://ntrs.nasa.gov/search.jsp?R=19790013166|journal=Lockheed Missiles and Space Company}}</ref> conducted for NASA:<blockquote>''"The results of the study showed that, with advanced technology, laser rocket system with either a space- or ground-based laser transmitter could reduce the national budget allocated to space transportation by 10 to 345 billion dollars over a 10-year life cycle when compared to advanced chemical propulsion systems (LO<sub>2</sub>-LH<sub>2</sub>) of equal capability."''</blockquote>

=== Beam director cost ===
The 1970s-era studies and others since have cited beam director cost as a possible impediment to beam-powered launch systems. A recent cost-benefit analysis<ref>{{Cite web|url=http://parkinresearch.com/microwave-thermal-rockets/|title=Microwave Thermal Rockets|last=Parkin|first=Kevin}}</ref> estimates that microwave (or laser) thermal rockets would be economical once beam director cost falls below 20 $/Watt. The current cost of suitable lasers is <100 $/Watt and the cost of suitable microwave sources is <$5/Watt. Mass production has lowered the production cost of microwave oven magnetrons to <0.01 $/Watt and some medical lasers to <10 $/Watt, though these are considered unsuitable for beam directors.