Arcjet rocket
Encyclopedia
Arcjets are a form of electric propulsion for spacecraft
, whereby an electrical discharge (arc) is created in a flow of propellant (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 station keeping in orbit and can replace monopropellant rocket
s.
In Germany
, researchers at the University of Stuttgart
's Institute of Space Aviation Systems have been looking into these challenges for years and have developed various hydrogen
-powered arcjet engines capable of power outputs from 1 to 100 kW
. The heated hydrogen reaches exit speeds of just under 10 miles per second (16 km/s). An arcjet-propelled test satellite by the name of Baden-Württemberg 1 (BW1) is scheduled to go to the moon.
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
, whereby an electrical discharge (arc) is created in a flow of propellant (typically hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
or ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
). 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
Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....
levels available from typically used arcjet engines are very low compared with chemical engines.
When the energy is available, arcjets are well suited to station keeping in orbit and can replace monopropellant rocket
Monopropellant rocket
A monopropellant rocket is a rocket that uses a single chemical as its propellant.-Chemical-reaction monopropellant rockets:...
s.
In Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, researchers at the University of Stuttgart
University of Stuttgart
The University of Stuttgart is a university located in Stuttgart, Germany. It was founded in 1829 and is organized in 10 faculties....
's Institute of Space Aviation Systems have been looking into these challenges for years and have developed various hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
-powered arcjet engines capable of power outputs from 1 to 100 kW
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
. The heated hydrogen reaches exit speeds of just under 10 miles per second (16 km/s). An arcjet-propelled test satellite by the name of Baden-Württemberg 1 (BW1) is scheduled to go to the moon.