An antimatter rocket is a proposed class of rockets that use antimatter as their power source. There are several types of design that attempt to accomplish this goal. The advantage to this class of rocket is that a large fraction of the rest mass of a matter/antimatter mixture may be converted to energy, allowing antimatter rockets to have a far higher energy density and specific impulse than any other proposed class of rocket. A Soyuz rocket, at Baikanur launch pad. ... For the physics of antimatter, see the article on antiparticles; for other senses of this term, see antimatter (disambiguation). ... Energy density is the amount of energy stored in a given system or region of space per unit volume or per unit mass, depending on the context. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ...

Antimatter rockets can be divided into three types: those that directly use the products of antimatter annihilation for propulsion, those that heat a working fluid which is then used for propulsion, and those that heat a working fluid to generate electricity for some form of electric spacecraft propulsion system. This article or section does not cite its references or sources. ...

Direct use of reaction products

Antiproton annihilation reactions produce charged and uncharged mesons, in addition to gamma rays. The charged mesons can be channelled by a magnetic nozzle, producing thrust. This type of antimatter rocket is a beamed core configuration. It is not perfectly efficient; energy is lost as the rest mass of the charged and uncharged mesons, lost as the kinetic energy of the uncharged mesons (which can't be deflected for thrust), and lost as gamma rays. The antiproton (aka pbar) is the antiparticle of the proton. ... Mesons of spin 1 form a nonet In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... This article is about electromagnetic radiation. ... This page is a candidate for speedy deletion. ...

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 to derive thrust from the annihilation reaction. No viable means of reflecting gamma rays has been proposed (no solid material has this property, and plasma is not sufficiently reflective to gamma rays under practically attainable conditions). The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... Eugen Sänger (September 22, 1905 - February 10, 1964) was an Austrian aerospace engineer best known for his contributions to lifting body and ramjet technology. ... Solar sails (also called light sails, especially when they use light sources other than the Sun) are a proposed form of spacecraft propulsion. ... A plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentation. ...

Antimatter heating of an exhaust fluid

Several methods for heating an exhaust fluid using the gamma rays produced by positron annihilation have been proposed^[1]. 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 annhilation 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. In a nuclear thermal rocket a working fluid, usually hydrogen, is heated in a high temperature nuclear reactor, and then expands through a rocket nozzle to create thrust. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Rocket Nozzle A nozzle is a mechanical device designed to control the characteristics of a fluid flow as it exits from an enclosed chamber into some medium. ... For Pb as an abbreviation, see PB. General Name, Symbol, Number lead, Pb, 82 Chemical series Post-transition metals or poor metals Group, Period, Block 14, 6, p Appearance bluish gray Standard atomic weight 207. ... General Name, Symbol, Number xenon, Xe, 54 Chemical series noble gases Group, Period, Block 18, 5, p Appearance colorless Standard atomic weight 131. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ...

Antimatter power generation

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 electric propulsion proposals (typically high specific impulse and low thrust). This article or section does not cite its references or sources. ... In a nuclear electric rocket, nuclear thermal energy is changed into electrical energy that is used to power one of the electrical propulsion technologies. ... In a nuclear thermal rocket a working fluid, usually hydrogen, is heated in a high temperature nuclear reactor, and then expands through a rocket nozzle to create thrust. ...

Difficulties with antimatter rockets

The chief practical difficulties with antimatter rockets are the problems of creating antimatter and storing antimatter. Creating antimatter requires input of vast amounts of energy, at least equivalent to the rest energy of the created particle/antiparticle pairs, and typically (for antiproton production) tens of thousands to millions of times more^{[citation needed]}. Most proposed antimatter rocket designs require a fairly small amount of antimatter (around 10 grams for a 11 month trip to Mars)[1] 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 2007 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. While there is no theoretical barrier to these tasks being performed on the scale required to fuel an antimatter rocket, they are expected to be extremely (and perhaps prohibitively) expensive^{[citation needed]}. 2007 is a common year starting on Monday of the Gregorian calendar. ... Penning traps are devices for the storage of charged particles using a constant magnetic field and a constant electric field. ... A quadrupole ion trap (also known as a Paul trap, QIT, twisted quadrupole ion trap or sometimes just ion trap) refers to an ion trap that uses static and radio frequency (RF) ~1MHz oscillating electric fields to trap ions as well a mass spectrometer that uses such a trap to...

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. Radiation hazard symbol. ...

See also

• Spacecraft propulsion
• Antimatter catalyzed nuclear pulse propulsion
• Redshift rocket

A remote camera captures a close-up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Propulsion means to add speed or acceleration to an object, by an engine or other similar device. ... Antimatter catalysed nuclear pulse propulsion is a variation of nuclear pulse propulsion based upon the injection of antimatter into a mass of nuclear fuel which normally would not be useful in propulsion. ... The redshift rocket, envisioned by novelist Karl Schroeder, is a fictional method of spacecraft propulsion. ...

References

1. ^ Smith, Gerald; Metzger, John; Meyer, Kirby; Thode, Les. Positron Propelled and Powered Space Transport Vehicle for Planetary Missions.