Busek Co. Inc. is an American spacecraft propulsion company providing thrusters, electronics, and complete systems for spacecraft.
Busek was founded in 1985 by Vlad Hruby and incorporated in Natick, Massachusetts. Starting as a small laboratory outside of Boston, Massachusetts, Busek facilities have expanded to over 20,000 square feet of laboratory, engineering, testing, and product assembly space.
Busek products have spaceflight heritage on several missions, including:
The first US Hall thruster flown in space, Busek's BHT-200, was launched aboard the Air Force Research Laboratory’s (AFRL) TacSat-2 satellite. The Busek thruster was part of the Microsatellite Propulsion Integration (MPI) Experiment and was integrated on TacSat-2 under the direction of the DoD Space Test Program. TacSat-2 launched on December 16, 2006 from the NASA Wallops Flight Facility. 
The first electrospray thruster in space was manufactured by Busek and launched aboard the European Space Agency's LISA Pathfinder satellite on December 3, 2015. The micro-newton colloid-style electric thruster was developed under contract with NASA’s Jet Propulsion Laboratory (NASA ST-7 Program), and part of NASA’s Disturbance Reduction System (DRS) which serves a critical role in the LISA Pathfinder science mission. 
Aerojet, under license with Busek, manufactured a 4 kW Hall thruster (the BPT-4000) which was flown aboard the USAF AEHF communications spacecraft. The thruster is credited with saving the first satellite by raising it to geosynchronous orbit after failure of the spacecraft's main apogee engine.
Busek will be providing Hall thrusters for NASA's Artemis Program. As part of the Power and Propulsion Element, Busek's 6kW Hall thrusters will work in combination with NASA's Advanced Electric Propulsion System to provide orbit raising and station keeping capabilities for the Lunar Gateway. The Lunar Gateway's unique polar near-rectilinear halo orbit (NRHO) will require periodic orbit adjustment, and electric propulsion will use solar energy for this task. 
Busek has demonstrated a variety of experimental xenon Hall thrusters at power levels up to and exceeding 20 kW. Busek has also developed Hall thrusters that operate on iodine, bismuth, carbon dioxide, magnesium, zinc, and other substances. In 2008, a xenon fueled Busek Hall thruster appeared in National Geographic. An iodine fueled 200 W Busek Hall thruster will fly on NASA's upcoming iSat (Iodine Satellite) mission. Busek is also preparing a 600 Watt iodine Hall thruster system for future Discovery Class missions. 
In September 2013, NASA awarded an 18‑month Phase I contract to Busek to develop an experimental concept called High Aspect Ratio Porous Surface (HARPS) microthruster system for use in tiny CubeSat spacecraft.
In order to deal with human-caused space debris, Busek proposed in 2014 a remotely controlled vehicle to rendezvous with debris, capture it, and attach a smaller deorbit satellite to the debris, then drag the debris/smallsat-combination, by means of a tether, to the desired location. The larger sat would then tow the debris/smallsat combination to either deorbit or move it to a higher graveyard orbit by means of electric propulsion. The larger satellite is named the ORbital DEbris Remover, or ORDER which will carry over 40 SUL (Satellite on an Umbilical Line) deorbit sats plus sufficient propellant for the large number of orbital maneuvers required to effect a 40-satellite debris removal mission over many years. Busek is projecting the cost for such a space tug to be US$80 million.