Editing Monopropellant rocket

{{more citations needed|date=August 2011}}
{{Short description|Rocket that uses a single propellant with a catalyst}}
A '''[[monopropellant]] rocket''' (or "'''monochemical rocket'''") is a [[rocket]] that uses a single [[chemical]] as its [[propellant]].{{contradictory inline|section=New developments|reason=The opening sentence here says a monopropellant is a single chemical;  the entire new developments section covers nothing but oxidizer / fuel propellants which are not single chemical.|date=April 2025}}<ref>{{Cite book |url=https://app.knovel.com/web/view/khtml/show.v/rcid:kpEDHEAMPH/cid:kt008MK1A8/viewerType:khtml//root_slug:engineering-design-handbook/url_slug:liquid-monopropellant?kpromoter=federation&view=collapsed&zoom=1&page=11 |title=United States Army: Elements of Aircraft and Missile Propulsion |date=July 1969 |publisher=United States Army Material Command |pages=1–11 |access-date=March 1, 2024 |department=Department of Defense}}</ref> Monopropellant rockets are commonly used as small attitude and trajectory control rockets in satellites, rocket upper stages, crewed spacecraft, and spaceplanes.<ref>{{Cite book |last1=Sutton |first1=George |title=Rocket Propulsion Elements |last2=Biblarz |first2=Oscar |publisher=Wiley-Interscience |isbn=0-471-32642-9 |edition=7th |pages=259}}</ref>

==Chemical-reaction based monopropellant rockets==
The simplest monopropellant rockets depend on the [[chemical decomposition]] of a storable propellant after passing it over a catalyst bed.<ref>{{Cite book |last1=Price |first1=T |title=The Status of Monopropellant Hydrazine Technology |last2=Evans |first2=D |date=February 15, 1968 |publisher=National Aeronautics and Space Administration |series=TR 32-1227 |location=Pasadena, California |pages=1–2}}</ref> The power for the thruster comes from the high pressure gas created during the decomposition reaction that allows a [[Rocket engine nozzle|rocket nozzle]] to speed up the gas to create thrust.

The most commonly used monopropellant is [[hydrazine]] ({{chem2|N2H4, or H2N\sNH2}}), a compound unstable in the presence of a [[Catalysis|catalyst]] and which is also a strong [[reducing agent]]. The most common catalyst is granular [[alumina]] (aluminum oxide, {{chem2|Al2O3}}) coated with [[iridium]]. These coated granules are usually under the commercial labels Aerojet S-405 (previously made by [[Shell plc|Shell]])<ref>{{cite web |url=http://ir.aerojetrocketdyne.com/releasedetail.cfm?releaseid=708514 |title=Aerojet Announces Licensing and Manufacture of Spontaneous Monopropellant Catalyst S-405 |work=aerojetrocketdyne.com |author=Aerojet Rocketdyne |date=12 Jun 2003 |access-date=9 Jul 2015 |archive-date=5 December 2017 |archive-url=https://web.archive.org/web/20171205194721/http://ir.aerojetrocketdyne.com/releasedetail.cfm?releaseid=708514 |url-status=dead }}</ref> or [[Heraeus#Sold, restructured and disinvested businesses|W.C. Heraeus]] H-KC 12 GA (previously made by Kali Chemie).<ref>{{cite book|author1=Wilfried Ley|author2=Klaus Wittmann|author3=Willi Hallmann|title=Handbook of Space Technology|url=https://books.google.com/books?id=5LBx4EmBix8C&pg=PA317|year=2009|publisher=John Wiley & Sons|isbn=978-0-470-74241-9|page=317}}</ref> There is no [[igniter]] with hydrazine.  Aerojet S-405 is a spontaneous catalyst, that is, hydrazine decomposes on contact with the catalyst. The [[Chemical decomposition|decomposition]] is highly [[exothermic]] and produces a {{convert|1000|C|F}} gas that is a mixture of [[nitrogen]], [[hydrogen]] and [[ammonia]]. The main limiting factor of the monopropellant rocket is its life, which mainly depends on the life of the catalyst. The catalyst may be subject to catalytic poisoning and catalytic attrition which results in the catalyst failure. Another monopropellant is [[hydrogen peroxide]], which, when purified to 90% or higher concentration, is self-decomposing at high temperatures or when a catalyst is present.

Most chemical-reaction monopropellant rocket systems consist of a [[fuel tank]], usually a [[titanium]] or [[aluminium]] sphere, with an [[Ethylene propylene rubber|ethylene-propylene rubber]] container or a [[surface tension]] [[propellant management device]] filled with the fuel. The tank is then pressurized with [[helium]] or [[nitrogen]], which pushes the fuel out to the motors. A [[Pipe (fluid conveyance)|pipe]] leads from the tank to a [[poppet valve]], and then to the decomposition chamber of the rocket motor. Typically, a [[satellite]] will have not just one motor, but two to twelve, each with its own valve.

The [[Spacecraft attitude control|attitude control]] rocket motors for satellites and [[space probe]]s are often very small, {{convert|25|mm|in|abbr=on}} or so in [[diameter]], and mounted in groups that point in four directions (within a plane).

The rocket is fired when the [[computer]] sends [[direct current]] through a small [[electromagnet]] that opens the poppet valve. The firing is often very brief, a few [[millisecond]]s, and — if operated in air — would sound like a pebble thrown against a metal trash can; if on for long, it would make a piercing hiss.

Chemical-reaction monopropellants are not as efficient as some other propulsion technologies. Engineers choose monopropellant systems when the need for simplicity and reliability outweigh the need for high delivered impulse. If the propulsion system must produce large amounts of thrust, or have a high [[specific impulse]], as on the main motor of an interplanetary spacecraft, other technologies are used.

==Solar-thermal based monopropellant thrusters==
A concept to provide [[low Earth orbit]] (LEO) [[propellant depot]]s that could be used as way-stations for other spacecraft to stop and refuel on the way to beyond-LEO missions has proposed that waste gaseous [[hydrogen]]—an inevitable byproduct of long-term [[liquid hydrogen]] storage in the [[Radiative heat transfer|radiative heat]] environment of [[outer space|space]]—would be usable as a monopropellant in a [[Solar thermal rocket|solar-thermal]] propulsion system.  The waste hydrogen would be productively utilized for both [[orbital stationkeeping|orbital station-keeping]] and attitude control, as well as providing limited propellant and thrust to use for [[Orbital maneuver#Non-impulsive maneuvers|orbital maneuvers]] to better [[Space rendezvous|rendezvous]] with other spacecraft that would be inbound to receive fuel from the depot.<ref name=aiaa20100902>
{{cite web |last=Zegler |first=Frank |title=Evolving to a Depot-Based Space Transportation Architecture |url=http://www.ulalaunch.com/site/docs/publications/DepotBasedTransportationArchitecture2010.pdf |work=AIAA SPACE 2010 Conference & Exposition |publisher=AIAA |access-date=2011-01-25 |author2=Bernard Kutter |date=2010-09-02 |page=3 |quote=the waste hydrogen that has boiled off happens to be the best known propellant (as a monopropellant in a basic solar-thermal propulsion system) for this task. A practical depot must evolve hydrogen at a minimum rate that matches the station keeping demands. |url-status=dead |archive-url=https://web.archive.org/web/20111020010301/http://www.ulalaunch.com/site/docs/publications/DepotBasedTransportationArchitecture2010.pdf |archive-date=2011-10-20 }}</ref>

Solar-thermal monopropellant thrusters are also integral to the design of a next-generation cryogenic [[upper stage]] [[rocket]] proposed by U.S. company [[United Launch Alliance]] (ULA).  The [[Advanced Common Evolved Stage]] (ACES) is intended as a lower-cost, more-capable and more-flexible upper stage that would supplement, and perhaps replace, the existing ULA [[Centaur (rocket stage)|Centaur]] and ULA [[Delta IV#Vehicle description|Delta Cryogenic Second Stage]] (DCSS) upper stage vehicles.  The ACES [[Integrated Vehicle Fluids]] option eliminates all [[hydrazine]] and [[helium]] from the space vehicle—normally used for attitude control and station keeping—and depends instead on solar-thermal monopropellant thrusters using waste hydrogen.<ref name=aiaa20100902_p5>Zegler and Kutter, 2010, p. 5.</ref>

== History ==
[[File:Lunar Landing Research Vehicle No. 2 in 1967 (ECN-1606) retouched.jpg|thumb|Lunar Landing Research Vehicle with 18 Hydrogen Peroxide Monopropellant Thrusters]]
Soviet designers had begun experimenting with monopropellant rockets as early as 1933.<ref name=":0" /> They believed their monopropellant mixes of [[Dinitrogen tetroxide|nitrogen tetroxide]] with gasoline, or toluene, and kerosene would lead to an overall simpler system; however, they ran into problems with violent explosions with pre-mixed fuel and oxidizer serving as a monopropellant that led the designers to abandon this approach.<ref name=":0">{{Cite book |last=Sutton |first=George |title=History of Liquid Propellant Rocket Engines |publisher=American Institute of Aeronautics and Astronautics |year=2006 |isbn=1563476495 |location=Reston, Virginia |pages=533–534}}</ref>

[[Hellmuth Walter|Helmuth Walter]] was a German engineer an early pioneer of monopropellant rockets using hydrogen peroxide as fuel.<ref name=":02">{{Cite web |last=Stokes |first=P. R. |date=14 January 1998 |title=Hydrogen Peroxide for Power and Propulsion |url=http://www.cue-dih.co.uk/aerospace/aeropdfs/htp_for_prop.pdf |url-status=dead |archive-url=https://web.archive.org/web/20060215104117/http://www.cue-dih.co.uk/aerospace/aeropdfs/htp_for_prop.pdf |archive-date=15 February 2006 |access-date=24 January 2024}}</ref> Although his initial work was on submarine propulsion the same jets of oxygen produced by for combustion in gas turbines could be directed through a nozzle to generate thrust.<ref name=":02" /> The rocket Walter developed was used in the German [[Messerschmitt Me 163 Komet|ME-163]] fighter aircraft in 1944, the first aircraft to break the 1000 km/h (635 mph).<ref name=":02" />  

After World War Two the British would continue to experiment with hydrogen peroxide monopropellants.<ref name=":02" /> They would develop the [[de Havilland Sprite]] a hydrogen peroxide rocket that could produce 5000lbf of thrust over 16 seconds. Not intended for space flight the rocket would provide hot and high takeoff capability to the [[De Havilland Comet|de Havilland Comet 1]] the first commercial jet airliner.<ref name=":02" /> 

In the United States, when NASA began studying monopropellants at the Jet Propulsion Laboratory (JPL) the properties of the existing propellants demanded that the thrusters be impractically large.<ref name=":1" /> The addition of a catalyst and pre-heating propellant made them more efficient, but raised concerns over safety and handling of hazardous propellants like anhydrous [[hydrazine]].<ref name=":1">{{Cite web |last1=Price |first1=T.W. |last2=Evans |first2=D. D. |date=February 15, 1968 |title=The Status of Monopropellant Hydrazine Technologies |url=https://ntrs.nasa.gov/api/citations/19680006875/downloads/19680006875.pdf |access-date=March 21, 2024 |series=TR 32-1227 |publisher=National Aeronautics and Space Administration |pages=1–2}}</ref> However the simplicity of the thrusters designed around early monopropellants offered many simplicities and were first tested in 1959 on the [[Pioneer P-3|Able-4]] mission.<ref name=":12" /> This test allowed for the [[Ranger program|Ranger]] and [[Mariner program|Mariner]] missions to use a similar thruster for correction maneuvers<ref name=":12">{{Cite web |last1=Price |first1=T.W. |last2=Evans |first2=D. D. |date=February 15, 1968 |title=The Status of Monopropellant Hydrazine Technologies |url=https://ntrs.nasa.gov/api/citations/19680006875/downloads/19680006875.pdf |access-date=March 21, 2024 |series=TR 32-1227 |publisher=National Aeronautics and Space Administration |pages=1–2}}</ref> and in the orbital insertion of [[Telstar]], considered by the National Air and Space Museum to be the most significant communications satellite in the beginning of the space race.<ref>{{Cite web |title=Telstar |url=https://airandspace.si.edu/collection-objects/communications-satellite-telstar/nasm_A20070113000 |access-date=March 8, 2024 |website=National Air and Space Museum}}</ref>
[[File:Centaur rocket stage.jpg|thumb|Centaur III Upper Stage with 12 Hydrazine Monopropellant Thrusters]]
In 1964, NASA began use of the [[Lunar Landing Research Vehicle]] to train Apollo astronauts in piloting the [[Apollo Lunar Module|Lunar Excursion Module]] (LEM) using an attitude control system consisting of 16 hydrogen peroxide monopropellant thrusters to steer the LEM to the lunar surface.<ref>{{Cite web |date=October 30, 2019 |title=55 Years Ago: The First Flight of the Lunar Landing Research Vehicle |url=https://www.nasa.gov/history/55-years-ago-the-first-flight-of-the-lunar-landing-research-vehicle/ |access-date=March 8, 2024 |website=National Aeronautics and Space Administration}}</ref>

Upper stage vehicles began using monopropellant thrusters as a convenient control device in the early 1960s when General Dynamics proposed the Centaur upper stage to the United States Airforce<ref>{{Cite web |last=Arrighi |first=Robert |title=Centaur: America's Workhorse in Space |url=https://www.nasa.gov/history/centaur-americas-workhorse-in-space/ |access-date=April 19, 2024 |publisher=National Aeronautics and Space Administration |publication-date=December 12, 2012}}</ref> of which versions are still in use in [[United Launch Alliance]]'s [[Atlas-Centaur|Atlas]] and [[Vulcan Centaur|Vulcan]] rockets.<ref>{{Cite web |year=2010 |title=Atlas V Users Guide |url=https://www.ulalaunch.com/docs/default-source/rockets/atlasvusersguide2010a.pdf?sfvrsn=f84bb59e_2 |access-date=April 19, 2024 |publisher=United Launch Alliance}}</ref>

==New developments==
NASA is developing a new monopropellant propulsion system for small, cost-driven spacecraft with [[delta-v]] requirements in the range of 10–150&nbsp;m/s. This system is based on a [[hydroxylammonium nitrate]] (HAN)/water/fuel monopropellant blend which is extremely dense, environmentally benign, and promises good performance and simplicity.<ref>{{Cite conference |last=Jankovsky |first=Robert S. |date=July 1–3, 1996 |title=HAN-Based Monopropellant Assessment for Spacecraft |url=https://ntrs.nasa.gov/citations/19960048008 |conference=32nd Joint Propulsion Conference |location=Lake Buena Vista, Florida |publisher=NASA |id=NASA Technical Memorandum 107287; AIAA-96-2863}}</ref>

The EURENCO Bofors company produced LMP-103S as a 1-to-1 substitute for hydrazine by dissolving 65% [[ammonium dinitramide]], NH<sub>4</sub>N(NO<sub>2</sub>)<sub>2</sub>, in 35% water solution of [[methanol]] and ammonia.  LMP-103S has 6% higher specific impulse and 30% higher impulse density than hydrazine monopropellant. Additionally, hydrazine is highly toxic and carcinogenic, while LMP-103S is only moderately toxic. LMP-103S is UN Class 1.4S allowing for transport on commercial aircraft, and was demonstrated on the [[Prisma (satellite project)|Prisma]] satellite in 2010. Special handling is not required. LMP-103S could replace hydrazine as the most commonly used monopropellant.<ref>{{Cite web |title=Green propellant LMP 103S |url=https://www.ecaps.se/rocket-fuel-1 |url-status=live |archive-url=https://web.archive.org/web/20240425184351/https://www.ecaps.se/rocket-fuel-1 |archive-date=April 25, 2024 |access-date=April 25, 2024 |website=ecaps.se}}</ref><ref>{{Cite web |title=High Performance Green Propulsion (LMP-103S) |url=https://www.ecaps.space/hpgp-performance.php |url-status=dead |archive-url=https://web.archive.org/web/20230607062315/https://www.ecaps.space/hpgp-performance.php |archive-date=June 7, 2023 |access-date=February 3, 2023 |website=ecaps.space}}</ref>

== See also ==
* [[Monopropellant]]
* [[Hypergolic propellant]]
* [[Liquid-propellant rocket]]
* [[Mars Reconnaissance Orbiter]]
* [[Reaction wheel]]
* [[Nitrous oxide fuel blend]]
*[[Rocket propulsion technologies (disambiguation)]]

==References==
{{Reflist}}

==External links==
* [http://www.hydrogen-peroxide.us/uses.htm Technical Reports on Hydrogen Peroxide as a Monopropellant for Rockets]
* [http://www.google.com/patents/US20090133788.pdf USPAT 20090133788 Nitrous oxide fuel blend monopropellants]{{dead link|date=January 2025|bot=medic}}{{cbignore|bot=medic}}
{{spacecraft propulsion}}

{{DEFAULTSORT:Monopropellant Rocket}}
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[[Category:Rocket engines by propellant]]
[[Category:Monopropellant rocket engines| ]]
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[[pt:Foguete monopropulsor]]