Aluminum-Ice Rocket Propellant, or ALICE, is a

rocket propellant Rocket propellant is used as reaction mass ejected from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines. Overvi ...

that consists of a frozen mixture of nano-aluminum powder and

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

(i.e.

aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

and

ice Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...

). Aluminum has a stronger affinity for oxygen than most elements, which is most visible in

aluminothermic reaction Aluminothermic reactions are exothermic reaction, exothermic chemical reactions using aluminium as the reducing agent at high temperature. The process is industrially useful for production of alloys of iron. The most prominent example is the the ...

s such as

thermite Thermite () is a pyrotechnic composition of powder metallurgy, metal powder and metal oxide. When ignited by heat or chemical reaction, thermite undergoes an exothermic redox, reduction-oxidation (redox) reaction. Most varieties are not explos ...

. This allows aluminum to burn with a large release of heat in substances that one normally considers to be inert, such as carbon dioxide and water. However, aluminum combustion is normally hindered by the presence of a durable oxide layer that forms on the surface of aluminum particles, requiring significant heat to overcome. Additionally,

aluminum oxide Aluminium oxide (or aluminium(III) oxide) is a chemical compound of aluminium and oxygen with the chemical formula . It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium oxide. It is commonly ...

condenses out of the exhaust stream at high temperature, leaving it (and its heat of condensation) unable to contribute to expansion without another gas present to function as a working fluid. This generally has relegated aluminum's role in rocketry to that of being an additive to

solid rocket A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses solid propellants (fuel/ oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder. The inception of gunpowder rockets in warfare can be cr ...

propellants, increasing their density and combustion temperature, and stabilizing the burn. The oxide layer in nano-aluminum powder, however, is thinner and easier to overcome than in that of larger particles, making the combustion of aluminum with water ice easier to ignite and sustain. Furthermore, as the aluminum consumes the oxygen, it liberates hydrogen which functions as a low-molecular-mass working fluid to translate the

heat of combustion The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it. The ''calorific value'' is the total energy relea ...

(and subsequently condensation) into expansion and thrust. The high density of the mixture allows for reduced tankage mass and high thrust. The base combustion reaction is: : . ALICE has been proposed as a propellant well-suited for on-site production on outer space bodies such as the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

, as both

(a source of aluminum) and water are abundant resources in the universe, while the high propellant density decreases the dry mass of the rocket. Maintaining the propellant in a frozen state is relatively simple on most bodies in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

, while other high-performance propellants often involve cryogenic fluids that can pose long-term storage problems. One production method is to combine the powder with ice using resonant acoustic mixing, providing a consistent and homogenous result.

References

External links

* * * * * {{Cite news , last=Bland , first=Eric , date=November 3, 2009 , title=Aluminum Fuel Could Power Future Space Trips , url=http://news.discovery.com/tech/nanoaluminum-rocket-fuel.html , archive-url=https://web.archive.org/web/20120615202926/http://news.discovery.com/tech/nanoaluminum-rocket-fuel.html , archive-date=June 15, 2012 , work=DiscoveryNews
University-produced development and flight video

Purdue Purdue University is a public land-grant research university in West Lafayette, Indiana, United States, and the flagship campus of the Purdue University system. The university was founded in 1869 after Lafayette businessman John Purdue donat ...

and

Penn State #Redirect Pennsylvania State University The Pennsylvania State University (Penn State or PSU) is a Public university, public Commonwealth System of Higher Education, state-related Land-grant university, land-grant research university with ca ...

students, August 2009 Rocket propellants Spacecraft propulsion Monopropellants

See also

References

External links