Editing Arcjet rocket (section)

{{Short description|Type of spacecraft electric propulsion system}}
An '''arcjet rocket''' or '''arcjet thruster''' is a form of [[electrically powered spacecraft propulsion]], in which an [[electrical discharge]] ([[arc discharge|arc]]) is created in a flow of propellant<ref>John, R. R., Bennett, S., and Connors, J. P., "Arcjet Engine Performance: Experiment and Theory," ''AIAA Journal, Vol. 1,'' No. 11, Nov. 1963. [http://arc.aiaa.org/doi/pdf/10.2514/3.2103 http://arc.aiaa.org/doi/pdf/10.2514/3.2103]</ref><ref>Wallner, Lewis E. and Czika, Joseph, Jr, ''[https://web.archive.org/web/20140909035419/http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA392837 ARC-Jet Thrustor for Space Propulsion],'' NASA Technical note TN D-2868, NASA Lewis Research Center, June 1965 (accessed September 8 2014)</ref> (typically [[hydrazine]] or [[ammonia]]). This imparts additional energy to the propellant, so that one can extract more work out of each kilogram of propellant, at the expense of increased power consumption and (usually) higher cost. Also, the [[thrust]] levels available from typically used arcjet engines are very low compared with chemical engines.

When the energy is available, arcjets are well suited to keeping stations in orbit and can replace [[monopropellant rocket]]s.

Aerojet [[MR-510]] series arcjet engines are currently used on [[Lockheed Martin A2100]] satellites using hydrazine as a propellant,<ref>{{cite web|title=Lockheed Martin Awards Aerojet Rocketdyne Contract to Provide Propulsion Subsystems on A2100 Satellites|url=http://www.nasdaq.com/press-release/lockheed-martin-awards-aerojet-rocketdyne-contract-to-provide-propulsion-subsystems-on-a2100-20150623-00960|website=Nasdaq|access-date=13 August 2015}}</ref> providing over 585 s average [[specific impulse]] at 2 [[Watt|kW]].<ref>{{cite book|title=30 Years of Electric Propulsion Flight Experience at Aerojet Rocketdyne|publisher=33rd International Electric Propulsion Conference|page=3}}</ref>

In [[Germany]], researchers at the [[University of Stuttgart]]'s Institute of Space Aviation Systems have been working with arcjets for years and have developed various [[hydrogen]]-powered arcjet engines capable of power outputs from 1 to 100&nbsp;kW. The heated hydrogen reaches exit speeds of {{convert|16|km/s}}. An arcjet-propelled test satellite by the name of [[Baden-Württemberg 1]] (BW1) was scheduled to go to the Moon by 2010. No such launch has yet occurred. Baden-Württemberg 1 would have used [[polytetrafluoroethylene]] (PTFE) propellant.<ref>[http://www.elringklinger.de/en/germany-land-of-ideas-elringklinger-drives-satellite Bietigheim-Bissingen, 11/20/2008] {{webarchive |url=https://web.archive.org/web/20140318021932/http://www.elringklinger.de/en/germany-land-of-ideas-elringklinger-drives-satellite |date=March 18, 2014 }}</ref>