Antimatter propulsion spacecraft

{{short description|Rockets using antimatter as their power source}} {{Antimatter}} An '''antimatter propulsion spacecraft''' is a proposed hypothetical class of space technology that utilize antimatter for power within spacecraft propulsion. There are several designs that attempt to accomplish this goal.

The theoretical advantage of yield by conversion of fuel using the antimatter-matter annihilative reaction is energy production at annihilation is the maximal currently known,<ref name=Musielak30012026>{{cite conference|author=Dora Musielak|author-link=Dora Musielak|location=The University of Texas at Arlington |date=July 2024|url=https://www.researchgate.net/publication/382049783_Study_of_Matter-Antimatter_Annihilation_as_Source_of_Energy_to_Power_Interstellar_Probe|title=Study of Matter-Antimatter Annihilation as Source of Energy to Power Interstellar Probe|conference=UTA Physics Colloquium - Spring Semester 2024|page=2, 10, 15|doi=10.13140/RG.2.2.22685.73445|via=Schmidt, G. 62nd IAC 2011 p.6792–6812|quote=Motivation and Research Objectives Matter-antimatter annihilation releases most energy per unit mass of any known reaction in physics}}</ref><ref name=Schmidt28012026>{{Cite book|last=Schmidt|first=George|title=62nd International Astronautical Congress 2011 : (IAC 2011) : Cape Town, South Africa, 3-7 October 2011.|publisher=International Astronautical Federation|year=2012|isbn=978-1-61839-805-5|location=Paris|pages=6792–6812|chapter=Nuclear Systems for Space Power and Production|oclc=795367347}}</ref> as the specific energy of antimatter is the most energy dense.<ref>{{cite conference|author1=Gerald A. Smith|author2=Dan P. Coughlin|location=Synergistic Technologies, Inc., East Gate Dr., Los Alamos & Penn State University|url=https://pubs.aip.org/aip/acp/article-abstract/552/1/939/572933/High-density-storage-of-antimatter-for-space?redirectedFrom=fulltext|title=High density storage of antimatter for space propulsion applications|conference=AIP Conf. Proc. 552, 939–943|date=2001|doi=10.1063/1.1358031|via=Schmidt, G. 62nd IAC 2011 p.6792–6812|quote=The specific energy of antimatter is 180 MJ/μg, making it the largest specific energy density material known to humankind.}}</ref><ref name=Schmidt28012026/>

Certain theoretical integral antimatter thruster performances have the necessary parameters for interstellar missions.<ref name=Frisbee12032026>{{cite conference|last=Frisbee|first=R.|date=2000|title=Systems-Level Modeling of a Beam-Core Matter-Antimatter Annihilation Propulsion System|url=https://dataverse.jpl.nasa.gov/file.xhtml?fileId=1267&version=2.0|conference=36th Joint Propulsion Conference, 'Huntsville, AL, USA|publisher=JPL Open Repository|quote=This Isp, corresponding to an effective exhaust velocity of 0.33c, makes the beam-core engine an attractive candidate for interstellar missions}}</ref>

==Annihilation== Protonic annihilation produces charged particles which can be confined and directed magnetically which is not the case in electronic. Antiproton annihilation reactions produce charged pions, in addition to neutrinos and gamma rays.<ref name=AIAA-2003-4696>{{cite conference|author=Robert H. Frisbee|location=Jet Propulsion Laboratory, California Institute of Technology|url=https://saismaran.org/howtobuildanantimatterrocket.pdf|title=How to Build an Antimatter Rocket for Interstellar Missions-----Systems level Considerations in Designing Advanced Propulsion Technology Vehicles|conference=39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Huntsville Alabama, July 20-23,2003|publisher=saismaran.org (url of a Physics PhD student at Duke University)|page=3 (Antimatter for Propulsion Applications)|via=trs-new.jpl.nasa.gov/dspace/bitstream/2014/38278/1/03-1942.pdf}} {{webarchive|url=https://web.archive.org/web/20150502002952/http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38278/1/03-1942.pdf |date=2015-05-02 }} </ref>

== Problems in design == The chief practical problems are creating antimatter and storing it.<ref>{{cite journal |last1=Chen |first1=Hui |last2=Wilks |first2=Scott C. |last3=Bonlie |first3=James D. |last4=Liang |first4=Edison P. |last5=Myatt |first5=Jason |last6=Price |first6=Dwight F. |last7=Meyerhofer |first7=David D. |last8=Beiersdorfer |first8=Peter |title=Relativistic Positron Creation Using Ultraintense Short Pulse Lasers |journal=Physical Review Letters |date=11 March 2009 |volume=102 |issue=10 |article-number=105001 |doi=10.1103/PhysRevLett.102.105001 |pmid=19392120 |bibcode=2009PhRvL.102j5001C }}</ref> ===Storage=== Most storage schemes proposed for interstellar craft require the production of frozen pellets of antihydrogen. This requires cooling of antiprotons, binding to positrons, and capture of the resulting antihydrogen atoms - tasks which have, {{As of|2010|lc=on}}, been performed only for small numbers of individual atoms. Storage of antimatter is typically done by trapping electrically charged frozen antihydrogen pellets in Penning or Paul traps. There is no theoretical barrier to these tasks being performed on the scale required to fuel an antimatter rocket. However, they are expected to be extremely (and perhaps prohibitively) expensive due to current production abilities being only able to produce small numbers of atoms, a scale approximately 10²³ times smaller than needed for a 10-gram trip to Mars.{{Citation needed|date=January 2026}} ===Energy output effect=== {{Anchor|effecient2016-01-30}}Generally, the energy from antiproton annihilation is deposited over such a large region that it cannot efficiently drive nuclear capsules. Antiproton-induced fission and self-generated magnetic fields may greatly enhance energy localization and efficient use of annihilation energy.<ref>{{cite journal |last1=Solem |first1=Johndale C. |title=Prospects for Efficient Use of Annihilation Energy |journal=Fusion Technology |date=December 1991 |volume=20 |issue=4P2 |pages=1040–1045 |doi=10.13182/FST91-A11946978 |bibcode=1991FuTec..20.1040S }}</ref><ref>{{cite journal|last1=Augenstein |first1=B. W.|last2=Solem|first2=J. C.|year=1990|title=Antiproton initiated fusion for spacecraft propulsion |journal=Report ND-3555-SDI (The RAND Corporation, Santa Monica, CA)}}{{vs|date=October 2025}}</ref> ====Extraction==== A secondary problem is the extraction of useful energy or momentum from the products of antimatter annihilation, which are primarily in the form of extremely energetic ionizing radiation. The antimatter mechanisms proposed to date have for the most part provided plausible mechanisms for harnessing energy from these annihilation products. The classic rocket equation with its "wet" mass (<math>M_0</math>)(with propellant mass fraction) to "dry" mass (<math>M_1</math>)(with payload) fraction (<math>\frac {M_0}{M_1}</math>), the velocity change (<math>\Delta v </math>) and specific impulse (<math>I_{\text{sp}}</math>) no longer holds due to the mass losses occurring in antimatter annihilation.<ref name=AIAA-2003-4696/> =====Modified relativistic rocket equation===== {{Further|Tsiolkovsky's rocket equation}} The loss of mass specific to antimatter annihilation requires a modification of the relativistic rocket equation given as<ref name=AIAA-98-3403>{{cite conference |last1=Frisbee |first1=R. H. |last2=Leifer |first2=S. D. |url=https://dataverse.jpl.nasa.gov/file.xhtml?fileId=43030&version=2.0|date=1998 |title=Evaluation of Propulsion Options for Interstellar Missions |hdl=2014/20238 |conference=AIAA Joint Propulsion Conference |location=Cleveland, OH, U.S.A. |publisher=JPL Open Repository }}</ref>

{{NumBlk|:|<math>\frac {M_0}{M_1} = \left(\frac{1+ \frac{\Delta v}{c}}{1- \frac{\Delta v}{c}}\right)^{\frac{c}{2 I_{\text{sp}}}} </math>|{{EquationRef|I}}}}

where <math>c</math> is the speed of light, and <math>I_{\text{sp}}</math> is the specific impulse (i.e. <math>I_{\text{sp}}</math>=0.69<math>c</math>).

The derivative form of the equation is<ref name=AIAA-2003-4696/>

{{NumBlk|:|<math>\frac {dM_{\text{ship}}}{M_{\text{ship}}}= \frac {-dv ( 1 - I_{\text{sp}} \frac {v}{c^2})} {(1 - \frac {v^2}{c^2})(-\frac {I_{\text{sp}} v^2}{c^2} + (1 - a) v + a I_{\text{sp}})} </math>|{{EquationRef|II}}}}

where <math>M_{\text{ship}}</math> is the non-relativistic (rest) mass of the rocket ship, and <math>a</math> is the fraction of the original (on board) propellant mass (non-relativistic) remaining after annihilation (i.e., <math>a</math>=0.22 for the charged pions).

Eq.II is difficult to integrate analytically. If it is assumed that <math>v \sim I_{\text{sp}}</math>, such that <math>(1 - \frac {I_{\text{sp}} v}{c^2}) \sim (1 - \frac {v^2}{c^2})</math> then the resulting equation is

{{NumBlk|:|<math>\frac {dM_{\text{ship}}}{M_{\text{ship}}}= \frac {-dv}{(-\frac {I_{\text{sp}} v^2}{c^2} + (1 - a) v + a I_{\text{sp}})} </math>|{{EquationRef|III}}}}

Eq.III can be integrated and the integral evaluated for <math>M_0</math> and <math>M_1</math>, and initial and final velocities (<math>v_i = 0</math> and <math>v_f = \Delta v</math>). The resulting relativistic rocket equation with loss of propellant is<ref name=AIAA-2003-4696/><ref name=AIAA-98-3403/>

{{NumBlk|:|<math>\frac{M_0}{M_1}=\left(\frac{(-2I_{\text{sp}}\Delta v/c^2+1-a-\sqrt{(1-a)^2+4aI_{\text{sp}}^2/c^2})(1-a+\sqrt{(1-a)^2+4aI_{\text{sp}}^2/c^2})}{(-2I_{\text{sp}}\Delta v/c^2+1-a+\sqrt{(1-a)^2+4aI_{\text{sp}}^2/c^2})(1-a-\sqrt{(1-a)^2+4aI_{\text{sp}}^2/c^2})}\right)^{\frac{1}{\sqrt{(1-a)^2+4aI_{\text{sp}}^2/c^2}}} </math>|{{EquationRef|IV}}}} ====Radiation damage==== Another general problem with high powered propulsion is excess heat or waste heat, and as with antimatter-matter annihilation also includes extreme radiation. A proton-antiproton annihilation propulsion system transforms 39% of the propellant mass into an intense high-energy flux of gamma radiation. The gamma rays and the high-energy charged pions will cause heating and radiation damage if they are not shielded against. Unlike neutrons, they will not cause the exposed material to become radioactive by transmutation of the nuclei. The components needing shielding are the crew, the electronics, the cryogenic tankage, and the magnetic coils for magnetically assisted rockets. Two types of shielding are needed: radiation protection and thermal protection (different from Heat shield or thermal insulation).<ref name=AIAA-2003-4696/><ref name=Forward1985>{{cite journal |last1=Forward |first1=Robert |title=Antiproton annihilation propulsion |journal=Journal of Propulsion and Power |date=September 1985 |volume=1 |issue=5 |pages=370–374 |doi=10.2514/3.22811 }}</ref> ===Relativity=== Finally, relativistic considerations have to be taken into account. As the by products of annihilation move at relativistic velocities the rest mass changes according to relativistic mass–energy. For example, the total mass–energy content of the neutral pion is converted into gammas, not just its rest mass. It is necessary to use a relativistic rocket equation that takes into account the relativistic effects of both the vehicle and propellant exhaust (charged pions) moving near the speed of light. These two modifications to the two rocket equations result in a mass ratio (<math>\frac {M_0}{M_1}</math>) for a given (<math>\Delta v </math>) and (<math>I_{\text{sp}}</math>) that is much higher for a relativistic antimatter rocket than for either a classical or relativistic "conventional" rocket.<ref name=AIAA-2003-4696/>

===Other general issues=== thumb|left|200px|A proposed antimatter rocket The cosmic background hard radiation will ionize the rocket's hull over time and poses a health threat. Also, gas plasma interactions may cause space charge. The major interaction of concern is differential charging of various parts of a spacecraft, leading to high electric fields and arcing between spacecraft components. This can be resolved with well placed plasma contactor. However, there is no solution yet for when plasma contactors are turned off to allow maintenance work on the hull. Long term space flight at interstellar velocities causes erosion of the rocket's hull due to collision with particles, gas, dust and micrometeorites. At 0.2<math>c</math> for a 6 light year distance, erosion is estimated to be in the order of about 30&nbsp;kg/m² or about 1&nbsp;cm of aluminum shielding.<ref name=NASA20110406>[https://web.archive.org/web/20110621012238/http://science1.nasa.gov/science-news/science-at-nasa/2001/ast13nov_1sidebar/ ''Space Charge''] NASA science news, April 6, 2011</ref><ref name=HGarrett>[http://www.kiss.caltech.edu/workshops/systems2012/presentations/garrett.pdf ''There and Back Again: A Layman's Guide to Ultra-Reliability for Interstellar Missions''] {{webarchive|url=https://web.archive.org/web/20140508062130/http://www.kiss.caltech.edu/workshops/systems2012/presentations/garrett.pdf |date=2014-05-08 }} Henry Garrett, 30 July 2012</ref>

==Antimatter production== ===Cost=== The cost of one gram of antimatter during the fall of 2003 (producer unknown) was 62.5 trillion dollars.<ref>{{cite web |author=David Newman |date=2003 |url=https://ffden-2.phys.uaf.edu/212_fall2003.web.dir/tyler_freeman/modern.htm |location=Geophysical Institute |title=Antimatter Now and Later |publisher=University of Alaska Fairbanks}} {{web archive|url=https://web.archive.org/web/20030902082154/https://ffden-2.phys.uaf.edu/212_fall2003.web.dir/tyler_freeman/modern.htm|date=2 September 2003}}</ref> Energy expenditure during 2011 for CERN 1g was stated as 25 million billion kWh costing more than 1 million billion Euros.<ref>{{cite web|url=https://angelsanddemons.web.cern.ch/antimatter/making-antimatter.html|title=Making antimatter|publisher=CERN|date=2011}}</ref>{{efn|This is equivalent to $1.392 quadrillion (2011 prices)}} in 2019 within CERN 1g was stated as being $2700 trillion.<ref>{{cite web|url=https://dcmp.org/media/13749-physics-girl-why-this-stuff-costs-2700-trillion-per-gram-antimatter-at-cern|title=Physics Girl: Why This Stuff Costs $2700 Trillion Per Gram--Antimatter at CERN|publisher=Described and Captioned Media Program|via=visit.cern/node/201}} {{web archive|url=https://web.archive.org/web/20201031212313/https://dcmp.org/media/13749-physics-girl-why-this-stuff-costs-2700-trillion-per-gram-antimatter-at-cern|date=31 October 2020}}</ref>{{efn|An estimated requirement for return journey to Jupiter with a payload of 10 - 100 metric tons is 1 - 10 micrograms.<ref name=Schmidt30012026>{{cite web|author1=G.R. Schmidt|display-authors=et al.|date=2012|title=Antimatter Requirements and Energy Costs for Near-term Propulsion Applicatins|url=https://ntrs.nasa.gov/api/citations/19990110316/downloads/19990110316.pdf|page=11|doi=10.2514/2.5661|publisher=NASA}}</ref> 1 microgram of antimatter 2003 is $62.5 million, CERN costs would be approximately $2.7 billion; estimated.

:<math>V 2026=V 2003 / 2019\times \frac {CPI2026} {CPI2003 / 2019}</math> :CPI 2003 is 184.000, 2019 is 255.658, 2026 is 324.122<ref>{{cite web|url=https://www.officialdata.org/us/inflation|title=CPI Inflation Calculator|publisher=officialdata.org|via=www.officialdata.org/us/inflation/2019?amount=27 www.officialdata.org/us/inflation/2003?amount=62}}</ref> 2026 cost of 2003 is $109.22 million; of 2019 is 3.423 billion.}} ====Potentially viable==== {{See also|Financial position of the United States|High-net-worth individual#UHNW characteristics}}

Cost of feasible (nuclear propulsive) quantities of available antimatter was estimated in 1999 as both $60 million per mission<ref name=Schmidt25032026>{{cite conference|last1=Schmidt|first1=G. R.|display-authors=et al|date=1 January 1999|location=NASA Marshall Space Flight Center, Pennsylvania State|url=https://ntrs.nasa.gov./citations/19990100915|title=Antimatter Production for Near-Term Propulsion Applications|publisher=NASA Technical Reports Server}}</ref> and $6.4 million (max.).<ref>{{cite conference|last1=Schmidt|first1=G. R.|display-authors=et al|date=1 January 1999|location=NASA Marshall Space Flight Center, Pennsylvania State|url=https://ntrs.nasa.gov./api/citations/19990110316/downloads/19990110316.pdf|title=Antimatter Production for Near-Term Propulsion Applications|publisher=NASA Technical Reports Server}}</ref> {{efn|The cost of 2003-2026 production of PC antimatter is estimated as 4.3688 quadrillion dollars which is 4.3688 × 10¹⁵ ($4,368,800,000,000,000)}}

===Rate=== The production rate of antimatter at CERN during 2009 was from 0.000000001 (1 billionth) to 0.00000001 (10 billionth) of a gram per year.<ref>{{cite book|author=Michio Kaku|author-link=Michio Kaku|date=2009|url=https://www.google.co.uk/books/edition/Physics_of_the_Impossible/coX3QMVjsYsC?hl=en&gbpv=0|chapter=Chapter 10. ANTIMATTER AND ANTI-UNIVERSES - PRODUCING ANTI-ATOMS AND ANTI-CHEMISTRY|title=Physics of the Impossible A Scientific Exploration of the World of Phasers, Force Fields, Teleportation and Time Travel|chapter-url=https://www.google.co.uk/books/edition/Physics_of_the_Impossible/coX3QMVjsYsC?hl=en&gbpv=1|publisher=Doubleday|ISBN=9780141030906}}</ref> ====Non-viable==== The antimatter requirement for a beamed-core power source for transit to the nearest<ref name=Schmidt30012026/> star — Proxima Centuri (4.2 light years away)<ref>{{cite web|author1=Deborah Byrd|author2=Kelly Kizer Whitt|date=22 October 2025|url=https://earthsky.org/astronomy-essentials/proxima-centauri-our-suns-nearest-neighbor/|title=Proxima Centauri, the closest star to our sun|publisher=EarthSky}}</ref> — is approximately 40 metric tonnes.<ref name=Schmidt30012026/> {{efn|The estimated time taken for PC mission generation at best-case 2009 rate of production is 4 quadrillion years}}

==Propulsion design== ===System=== The propulsion system is:<ref>{{cite web|author=David L. Morgan Jnr.|location=Polaris Way, Livermore, California|url=https://ntrs.nasa.gov/api/citations/19820013176/downloads/19820013176.pdf|title=CONCEITS FOR THE DESIGN OF AN ANTIMATTTEk ANNILHLLATLON ROCKET|page=3 - 1.introduction|publisher=NASA Technical Reports Server=ntrs.nasa.gov|publication-date=March 1982}}</ref> :1. Premade and, or, an onboard antimatter generator{{efn|An antiproton flux produced by spallation exists in interstellar medium<ref>{{cite journal|author=F. Donato |display-authors=et al.|location=Laboratoire de Physique Théorique (Annecy-le-Vieux); Université de Savoie; Université Joseph Fourier|url=https://iopscience.iop.org/article/10.1086/323684/fulltext/53633.text.html|title=Antiprotons from Spallations of Cosmic Rays on Interstellar Matter|journal=The Astrophysical Journal|volume=563|publication-date=10 December 2001 |publisher=The American Astronomical Society}}</ref> cosmic rays<ref>{{cite journal|author1=Michael Kachelriess|author2= Igor V. Moskalenko|author3=Sergey S. Ostapchenko|location=NTNU; Stanford University; Lomonosov Moscow State University, 119991 Moscow, Russia|date=2015 |url=https://iopscience.iop.org/article/10.1088/0004-637X/803/2/54/pdf|title=NEW CALCULATION OF ANTIPROTON PRODUCTION BY COSMIC RAY PROTONS AND NUCLEI|journal=The Astrophysical Journal|publication-date=20 April 2015|volume=803|issue=54|publisher=The American Astronomical Society: iop.org|DOI=10.1088/0004-637X/803/2/54|quote=Antiprotons in cosmic rays (CR) are produced in CR interactions with interstellar gas and are, therefore, called secondary. - antiproton “background” - in contrast to CR positrons that can be produced copiously in pulsars, there is no known astrophysical source of primary antiprotons}}</ref>}} :2. Storage :3. A way to separate or extract a certain amount of antimatter from the storage mass at the necessary rate :4. Generation of motion of antimatter as transferal to the annihilation location :5. An annihilation chamber :6. Control or channel of antimatter products as thrust

===Methods=== Theoretical antimatter inclusion propellant methods:<ref name=Musielak30012026/> :Beam: annihilation product only :Nuclear hybrid: with fusion and{{efn|Which is: fission instigates fusion <ref name=tajmar>{{cite book|author=martin tajmar|date=8 September 2012|location=ARC Seibersdorf Research GmBH, Seibersdorf|chapter-url=https://www.google.co.uk/books/edition/Advanced_Space_Propulsion_Systems/zK3wCAAAQBAJ?hl=en&gbpv=1&dq=fission+antimatter+propulsion&pg=PA72&printsec=frontcover|chapter=4. Nuclear Propulsion Systems|title=advanced space propulsion systems|page=72: 4.5 Antimatter Propulsion|publisher=Springer-Verlag Wien GmbH|ISBN=3709105471}}</ref>}} or fission: ::antiparticles to create or catalyse a reaction ::radioisotope :Thermal:<ref name=Lafleur10032026>{{cite journal|last=Lafleur|first=Trevor|location=PlasmaPotential - Physics Consulting and Research, Canberra|url=https://www.sciencedirect.com/science/article/abs/pii/S0094576521005865|title=Evaluation of solid-core thermal antimatter propulsion concepts|journal=Acta Astronautica|volume=191|issue=February 2022|doi=10.1016/j.actaastro.2021.10.045}}</ref> ::plasma core ::solid core :::annihilation particles contained within the propulsion generator and controlled for heating a rocket working fluid ::::using conventional propellants: carbon dioxide, hydrogen, methane, water<ref name=Lafleur10032026/> :::electricity generation<ref name=Lafleur10032026/> ::::using electro-thruster types: arcjet, gridded ion, Hall thruster<ref name=Lafleur10032026/>

The alternatives to direct antimatter annihilation propulsion offer the possibility of feasible vehicles with, in some cases, vastly smaller amounts of antimatter but require a lot more matter propellant.<ref name=ADA446638>{{cite journal|author=Claude Deutsch|date=October 2006|location=University of Paris-Saclay |url=https://www.researchgate.net/publication/231788463_Fusion_reactions_and_matter-antimatter_annihilation_for_space_propulsion|title=Fusion Reactions and Matter-Antimatter Annihilation for Space Propulsion|journal=Laser and Particle Beams|doi=10.1017/S0263034606060691|volume=24|issue=04|ISSN=1469-803X|publisher=Cambridge University Press|editor=Katarzyna Batani|via=apps.dtic.mil/dtic/tr/fulltext/u2/a446638.pdf}}{{Webarchive|url=https://web.archive.org/web/20231004161223/https://apps.dtic.mil/dtic/tr/fulltext/u2/a446638.pdf |date=2023-10-04 }}</ref>

====Beam antimatter rocket: direct use of reaction products==== Charged pions can be channelled by a magnetic nozzle, producing thrust. This type of antimatter rocket is a '''pion rocket''' or '''beamed core''' configuration.<ref name=AIAA-2003-4696/>

Positron annihilation has also been proposed for rocketry. Annihilation of positrons produces only gamma rays. Early proposals for this type of rocket, such as those developed by Eugen Sänger, assumed the use of some material that could reflect gamma rays, used as a light sail or parabolic shield to derive thrust from the annihilation reaction, but no known form of matter (consisting of atoms or ions) interacts with gamma rays in a manner that would enable specular reflection. The momentum of gamma rays can, however, be partially transferred to matter by Compton scattering.<ref name=AIAA-2001-3231>{{cite conference|author1=Darrel Smith|author2=Jonathan Webb|date=July 2001|url=https://lifeboat.com/pdfs/antimatter.pdf|title=The Antimatter Photon Drive: A Relativistic Propulsion System|location=Embry-Riddle Aeronautical University|publisher=American Institute of Aeronautics and Astronautics: lifeboat.com |conference=AIAA 37th Joint Propulsion Conference and Exhibit|doi=10.2514/6.2001-3231|via=physicsx.pr.erau.edu/ExoticPropulsion/propulsion2.pdf}}</ref><ref name=WebbTATRSBCAR>[http://physicsx.pr.erau.edu/ExoticPropulsion/APD/APD%20Word/Thermal.pdf ''Thermal Analysis of a Tungsten Radiation Shield for Beamed Core Antimatter Rocketry''] Jonathan A. Webb</ref>

One method to reach relativistic velocities uses a matter-antimatter GeV gamma ray laser photon rocket made possible by a relativistic proton-antiproton pinch discharge, where the recoil from the laser beam is transmitted by the Mössbauer effect to the spacecraft.<ref name="AA-20120821">{{cite journal |last=Winterberg |first=F. |title=Matter–antimatter gigaelectron volt gamma ray laser rocket propulsion |date=21 August 2012 |journal=Acta Astronautica |volume=81 |issue=1 |pages=34–39 |bibcode = 2012AcAau..81...34W |doi = 10.1016/j.actaastro.2012.07.001 }}</ref>

A new annihilation process has purportedly been developed by researchers from the University of Gothenburg, Sweden. Several annihilation reactors have been constructed in the past years{{when|date=November 2024|reason=which past years?}} which attempted to convert hydrogen or deuterium into relativistic particles through laser annihilation. The technology was explored by research groups led by Prof. Leif Holmlid and Sindre Zeiner-Gundersen, and a third relativistic particle reactor is currently being built at the University of Iceland. In theory, emitted particles from hydrogen annihilation processes could reach 0.94c and can be used in space propulsion.<ref>{{cite journal |last1=Holmlid |first1=Leif |last2=Zeiner-Gundersen |first2=Sindre |title=Future interstellar rockets may use laser-induced annihilation reactions for relativistic drive |journal=Acta Astronautica |date=October 2020 |volume=175 |pages=32–36 |doi=10.1016/j.actaastro.2020.05.034 |bibcode=2020AcAau.175...32H |doi-access=free |hdl=20.500.11815/2191 |hdl-access=free }}</ref> However the veracity of Holmlid's research is under dispute and no successful implementations have been peer reviewed or replicated.<ref>{{cite report |type=Preprint |last1=Hansen |first1=Klavs |last2=Engelen |first2=Jos |title=Comment on 'Ultradense protium p(0) and deuterium D(0) and their relation to ordinary Rydberg matter: A review' 2019 Physica Scripta 94, 075005 |date=2022 |arxiv=2207.08133 }}</ref> ====Nuclear catalyzed fission/fusion or spiked fusion====

This is a hybrid approach in which antiprotons are used to catalyze a fission/fusion reaction or to "spike" the propulsion of a fusion rocket or any similar applications.

The antiproton-driven Inertial confinement fusion (ICF) Rocket concept uses pellets for the D-T reaction. The pellet consists of a hemisphere of fissionable material such as U²³⁵ with a hole through which a pulse of antiprotons and positrons is injected. It is surrounded by a hemisphere of fusion fuel, for example deuterium-tritium, or lithium deuteride. Antiproton annihilation occurs at the surface of the hemisphere, which ionizes the fuel. These ions heat the core of the pellet to fusion temperatures.<ref name=NIAC98-02FR>{{cite book |last1=Kammash |first1=Terry |last2=Galbraith |first2=David L. |last3=Cassenti |first3=Brice N. |title=AIP Conference Proceedings |chapter=An antiproton-driven magnetically insulated inertial fusion propulsion system |date=1995 |volume=324 |pages=567–570 |doi=10.1063/1.47235 }}</ref>

The antiproton-driven Magnetically Insulated Inertial Confinement Fusion Propulsion (MICF) concept relies on self-generated magnetic field which insulates the plasma from the metallic shell that contains it during the burn. The lifetime of the plasma was estimated to be two orders of magnitude greater than implosion inertial fusion, which corresponds to a longer burn time, and hence, greater gain.<ref name=NIAC98-02FR/>

The antimatter-driven P-B¹¹ concept uses antiprotons to ignite the P-B¹¹ reactions in an MICF scheme. Excessive radiation losses are a major obstacle to ignition and require modifying the particle density, and plasma temperature to increase the gain. It was concluded that it is entirely feasible that this system could achieve I_sp~10⁵s.<ref name=NASA7347634540>{{cite journal |last1=Kammash |first1=Terry |last2=Martin |first2=James |last3=Godfroy |first3=Thomas |title=Antimatter Driven P-B11 Fusion Propulsion System |journal=AIP Conference Proceedings |date=17 January 2003 |volume=654 |issue=1 |pages=497–501 |doi=10.1063/1.1541331 |bibcode=2003AIPC..654..497K |hdl=2027.42/87345 |hdl-access=free }}</ref>

A different approach was envisioned for AIMStar in which small fusion fuel droplets would be injected into a cloud of antiprotons confined in a very small volume within a reaction Penning trap. Annihilation takes place on the surface of the antiproton cloud, peeling back 0.5% of the cloud. The power density released is roughly comparable to a 1 kJ, 1 ns laser depositing its energy over a 200&nbsp;μm ICF target.<ref name=AIAA-99-2700>{{cite book |last1=Lewis |first1=Raymond |last2=Meyer |first2=Kirby |last3=Smith |first3=Gerald |last4=Howe |first4=Steven |title=35th Joint Propulsion Conference and Exhibit |chapter=AIMStar - Antimatter Initiated Microfusion for pre-cursor interstellar missions |date=1999 |doi=10.2514/6.1999-2700 }}</ref>

The ICAN-II project employs the antiproton catalyzed microfission (ACMF) concept which uses pellets with a molar ratio of 9:1 of D-T:U²³⁵ for nuclear pulse propulsion.<ref name=AIAA-1998-3589>{{cite book |last1=Gaidos |first1=G. |last2=Laiho |first2=J. |last3=Lewis |first3=R. A. |last4=Smith |first4=G. A. |last5=Dundore |first5=B. |last6=Fulmer |first6=J. |last7=Chakrabarti |first7=S. |title=AIP Conference Proceedings |chapter=Antiproton-catalyzed microfission/fusion propulsion systems for exploration of the outer solar system and beyond |date=1998 |volume=420 |pages=1365–1372 |doi=10.1063/1.54761 }}</ref>

====Thermal antimatter rocket: heating of a propellant====

This type of antimatter rocket is termed a '''thermal antimatter rocket''' as the energy or heat from the annihilation is harnessed to create an exhaust from non-exotic material or propellant.

The '''solid core''' concept uses antiprotons to heat a solid, high-atomic weight ('''''Z'''''), refractory metal core. Propellant is pumped into the hot core and expanded through a nozzle to generate thrust. The performance of this concept is roughly equivalent to that of the nuclear thermal rocket (<math>I_{\text{sp}}</math> ~ 10³ sec) due to temperature limitations of the solid. However, the antimatter energy conversion and heating efficiencies are typically high due to the short mean path between collisions with core atoms (efficiency <math>\eta_e</math> ~ 85%).<ref name=ADA446638/> Several methods for the '''liquid-propellant thermal antimatter engine''' using the gamma rays produced by antiproton or positron annihilation have been proposed.<ref name=Vulpetti1987>{{cite journal |last1=Vulpetti |first1=G. |title=A further analysis about the liquid-propellant thermal antimatter engine design concept |journal=Acta Astronautica |date=August 1987 |volume=15 |issue=8 |pages=551–555 |doi=10.1016/0094-5765(87)90155-X |bibcode=1987AcAau..15..551V }}</ref><ref>{{cite web |title= Positron Propelled and Powered Space Transport Vehicle for Planetary Missions |url= http://www.niac.usra.edu/files/library/meetings/fellows/mar06/1147Smith.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.niac.usra.edu/files/library/meetings/fellows/mar06/1147Smith.pdf |archive-date=2022-10-09 |url-status=live |last= Smith |first= Gerald |author2= Metzger, John|author3= Meyer, Kirby|author4= Thode, Les |date=2006-03-07 |access-date=2010-04-21}}</ref> These methods resemble those proposed for nuclear thermal rockets. One proposed method is to use positron annihilation gamma rays to heat a solid engine core. Hydrogen gas is ducted through this core, heated, and expelled from a rocket nozzle. A second proposed engine type uses positron annihilation within a solid lead pellet or within compressed xenon gas to produce a cloud of hot gas, which heats a surrounding layer of gaseous hydrogen. Direct heating of the hydrogen by gamma rays was considered impractical, due to the difficulty of compressing enough of it within an engine of reasonable size to absorb the gamma rays. A third proposed engine type uses annihilation gamma rays to heat an ablative sail, with the ablated material providing thrust. As with nuclear thermal rockets, the specific impulse achievable by these methods is limited by materials considerations, typically being in the range of 1000–2000 seconds.<ref name=Vulpetti1989>{{cite journal |last1=Vulpetti |first1=Giovanni |last2=Pecchioli |first2=Mauro |title=Considerations about the specific impulse of an antimatter-based thermal engine |journal=Journal of Propulsion and Power |date=September 1989 |volume=5 |issue=5 |pages=591–595 |doi=10.2514/3.23194 }}</ref>

The '''gaseous core''' system substitutes the low-melting point solid with a high temperature gas (i.e. tungsten gas/plasma), thus permitting higher operational temperatures and performance (<math>I_{\text{sp}}</math> ~ 2 × 10³ sec). However, the longer mean free path for thermalization and absorption results in much lower energy conversion efficiencies (<math>\eta_e</math> ~ 35%).<ref name=ADA446638/>

The '''plasma core''' allows the gas to ionize and operate at even higher effective temperatures. Heat loss is suppressed by magnetic confinement in the reaction chamber and nozzle. Although performance is extremely high (<math>I_{\text{sp}}</math> ~ 10⁴-10⁵ sec), the long mean free path results in very low energy utilization (<math>\eta_e</math> ~ 10%).<ref name=ADA446638/>

=====Electro===== The idea of using antimatter to power an electric space drive has also been proposed. These proposed designs are typically similar to those suggested for nuclear electric rockets. Antimatter annihilations are used to directly or indirectly heat a working fluid, as in a nuclear thermal rocket, but the fluid is used to generate electricity, which is then used to power some form of electric space propulsion system. The resulting system shares many of the characteristics of other charged particle/electric propulsion proposals, that typically being high specific impulse and low thrust (see also [http://large.stanford.edu/courses/2017/ph240/payzer1/ antimatter power generation]).<ref name=Seitzman>[http://soliton.ae.gatech.edu/people/jseitzma/classes/ae4451/electricpropulsion2.pdf ''Electric Rocket Propulsion: A Background''] {{Webarchive|url=https://web.archive.org/web/20130805125119/http://soliton.ae.gatech.edu/people/jseitzma/classes/ae4451/electricpropulsion2.pdf |date=2013-08-05 }} Jerry M. Seitzman, 2003-2004</ref><ref name=US20140026535A1>[https://patents.google.com/patent/US20140026535 ''High Specific Impulse Superfluid and Nanotube Propulsion Device, System and Propulsion Method''] Michael Wallace, Joseph D. Nix, Christopher W. Smith, 2014</ref> ===Relative powers=== ====Efficiency==== :'''Beam''': 100% mass=energy though estimated 70% available.<ref>{{cite journal|last1= Omira |first1=Sawsan|last2=Mourad|first2=Abdel|location=United Arab Emirates University, Al-Ain|editor=Xiande Fang / Hussam Jouhara|title=Future of antimatter production, storage, control, and annihilation applications in propulsion technologies|url=https://www.sciencedirect.com/science/article/pii/S2666202724004518|journal=International Journal of Thermofluids|volume=25|issue=January 2025|doi=10.1016/j.ijft.2024.101012|quote=Abstract Utilizing antimatter annihilation - 100% efficiency when antimatter meets matter. Approximately 70% of this energy can be harnessed for propulsion}}</ref> Proton-Antiproton annihilation (p{{SubatomicParticle|Antiproton}} annihilation) estimated utilisable product-energy per stage of three product types: pion, 40% of energy caused by initial annihilation at this product stage is utilisable, muon 31%, positron-electron 16%<ref name=LaPointe11032026>{{cite web|last= LaPointe|first=Mike|date=1 February 2020|location=NASA Marshall Space Flight Center|title=Antimatter Propulsion: Antimatter Propulsion Concepts: Proton-Antiproton Beam Core Engine|url=https://ntrs.nasa.gov/api/citations/20200001904/downloads/20200001904.pdf}}</ref> Not perfectly efficient; energy is lost as the rest mass of the charged (22.3%) and uncharged pions (14.38%), lost as the kinetic energy of the uncharged pions (which can't be deflected for thrust); and lost as neutrinos and gamma rays (see antimatter as fuel).<ref name=AIAA-2003-4696/> :'''Fission''': (using uranium) 0.1% mass post reaction outputs energy.<ref>{{cite web|author=M. Ripani|date=2019|location=INFN|url=https://static.sif.it/SIF/resources/public/files/va2019/ripani1.pdf|title=Energy from nuclear fission: basics|publisher=Joint EPS-SIF International School on Energy|quote=Amount of energy and reaction products When a uranium nucleus fissions into two daughter nuclei fragments, about 0.1 % of uranium mass appears as fission energy}}</ref> Catalysticalized anti-protonic neutron output is a range of a six-multiple of the power of conventional process.<ref name=tajmar/>

====Thrust speed==== :'''Beam''' :Keane ''et al'' 2012: Monte Carlo simulation using Geant4: v_e ~ 0.69c.<ref>{{cite journal |last1=Keane |first1=Ronan|location=Cornell University |last2=Zhang |first2=Wei-Ming |date=January 2012 |title=Beamed Core Antimatter Propulsion: Engine Design and Optimization|journal=Journal of the British Interplanetary Society|arxiv=1205.2281|quote=www.researchgate.net/publication/224934449_Beamed_Core_Antimatter_Propulsion_Engine_Design_and_Optimization}}</ref> {{math|''I''_sp}}{{efn|{{math|''I''_sp}} is Impulse ({{math|''I''}}) + specific ({{math|_sp}})}} is 2.8 × 10⁷ seconds (s)<ref name=LaPointe11032026/>{{efn|(10⁷ s<ref>{{cite web|author1=G.A. Smith|author2=K.J. Kramer|author3=K.J. Meyer|date=2001|location=Synergistic Technologies Corporation Los Alamos; Pennsylvania State University|url=https://nss.org/wp-content/uploads/Space-Manufacturing-conference-13-069-Antimatter-Initiated-Microfission-Fusion.pdf |title=ANTIMATTER-INITIATED MICROFISSION/ FUSION: CONCEPT, MISSIONS, AND SYSTEMS STUDIES FOR EXPLORATION OF DEEP SPACE|page=69|publisher=Space Studies Institute: nss.org}}</ref><ref name=Frisbee12032026/> being 0.33c<ref name=Frisbee12032026/>)}} :'''Nuclear pulse'''<ref name=Matloff25032026>{{cite book|author=Gregory L. Matloff|editor=John Mason|location=New York University|chapter-url=https://www.google.com/books/edition/Deep_Space_Probes/x8LgBwAAQBAJ?hl=en&gbpv=1&dq=ANTIMATTER+STORAGE&pg=PA78&printsec=frontcover|title= Deep-Space Probes|chapter=Chapter 6: The Nuclear Option|page=78|publisher=Springer-Praxis|publication-date=27 November 2013|ISBN=9781447136415|quote=Schmidt ''et al''. have recently examined the cost saving if tiny amounts of antimatter are used - specific impulse for such an antimatter interstellar-precursor mission is }}</ref> :Schmidt ''et al'' 1999:<ref name=Schmidt25032026/><ref name=Matloff25032026/> 13600 - 67000s {{math|''I''}}{{math|_sp}}<ref name=Matloff25032026/>

==See also== *Nuclear photonic rocket ==Notes== {{notelist}} ==References== {{reflist|30em}}

Category:Antimatter Category:Rocket propulsion