A colloid thruster (or "

electrospray The name electrospray is used for an apparatus that employs electricity to disperse a liquid or for the fine aerosol resulting from this process. High voltage is applied to a liquid supplied through an emitter (usually a glass or metallic capilla ...

thruster") is a type of low thrust electric propulsion

rocket engine A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accorda ...

that uses electrostatic acceleration of charged liquid droplets for propulsion. In a

colloid A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend ...

thruster, charged liquid droplets are produced by an electrospray process and then accelerated by a static electric field. The liquid used for this application tends to be a low-volatility

ionic liquid An ionic liquid (IL) is a salt in the liquid state. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as . While ordinary liquids such as water and gasoline are predominantly made of ...

. Like other

ion thruster An ion thruster, ion drive, or ion engine is a form of electric propulsion used for spacecraft propulsion. It creates thrust by accelerating ions using electricity. An ion thruster ionizes a neutral gas by extracting some electrons out of ...

s, its benefits include high efficiency, thrust density, and

specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...

; however it has very low total thrust, on the order of micronewtons. It provides very fine

attitude control Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle ...

or efficient acceleration of small spacecraft over long periods of time.

Flight use

Eight electrospray thrusters were first used in space on the NASA ST-7 ESA LISA Pathfinder mission, to demonstrate disturbance reduction. Having logged roughly 1,400 hours on-orbit, the Busek built thrusters system met 100% of their mission goals for the LISA Pathfinder mission. By the end of April 2015, Busek had developed a smaller electrospray colloid thruster capable of generating 20 mN in a 17.8 x 17.8 x 4.3 cm (7"×7"×1.7") package.

Experiments

In July 2013, scientists from

Michigan Technological University Michigan Technological University (Michigan Tech, MTU, or simply Tech) is a public research university in Houghton, Michigan, founded in 1885 as the Michigan Mining School, the first post-secondary institution in the Upper Peninsula of Michiga ...

and the

University of Maryland The University of Maryland, College Park (University of Maryland, UMD, or simply Maryland) is a public land-grant research university in College Park, Maryland. Founded in 1856, UMD is the flagship institution of the University System of ...

led by Kurt Terhune demonstrated an electrospray system within a

transmission electron microscope Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a gr ...

(TEM). This led to the discovery that the TEM environment formed needle-like structures on the thruster disrupting the way the electrospray system works.Watch a Tiny Space Rocket Work
Allison Mills,

Michigan Tech Michigan Technological University (Michigan Tech, MTU, or simply Tech) is a public research university in Houghton, Michigan, founded in 1885 as the Michigan Mining School, the first post-secondary institution in the Upper Peninsula of Michiga ...

, 8 August 2016, accessed 11 August 2016 The SkyFire nanosatellite, to be launched in 2021 for a lunar flyby, will demonstrate the use of this propulsion system.

References

External links

Colloid Thruster Lecture Notes - MIT
Engines Spacecraft propulsion Electrostatic motors {{Space-stub

Flight use

Experiments

See also

References

External links