&lt;p&gt;Propulsion technology is often critical for space missions.&amp;nbsp;High-value missions could be done with very&amp;nbsp;small spacecraft, even CubeSats, but these nanosatellites&amp;nbsp;currently have little propulsion capability. After&amp;nbsp;CubeSats are deployed, they usually just tumble or drift&amp;nbsp;away from the transport spacecraft. They cannot transfer&amp;nbsp;to higher value orbits, maintain their orbit, or even&amp;nbsp;deorbit. Larger spacecraft would benefit from highprecision&amp;nbsp;attitude-control systems to maintain the&amp;nbsp;desired orbit and point in the desired direction. Existing&amp;nbsp;attitude-control systems, like reaction wheels, are very&amp;nbsp;complex and may have insufficient lifetimes. NASA is&amp;nbsp;investing in Microfluidic Electrospray Propulsion (MEP)&amp;nbsp;thrusters to provide the new propulsion capabilities to&amp;nbsp;address both of these mission needs.&lt;/p&gt;&lt;p&gt;Chemical propulsion systems are limited to the combustion&amp;nbsp;energy available in the chemical bonds of the&amp;nbsp;fuel and the acceleration provided by a converging-diverging&amp;nbsp;nozzle. Electric propulsion uses electric&amp;nbsp;power to accelerate propellant to very high exhaust&amp;nbsp;velocities&amp;mdash;up to 10 times greater than for chemical&amp;nbsp;propulsion. This increases the momentum transfer efficiency&amp;nbsp;or the fuel economy. The propellant efficiency of&amp;nbsp;thrusters, which is proportional to the exhaust velocity,&amp;nbsp;is referred to as the &amp;ldquo;specific impulse,&amp;rdquo; or ISP, measured&amp;nbsp;in seconds. The state of the art for CubeSats is cold&amp;nbsp;gas propulsion with an ISP of 50 to 80 s. The chemical&amp;nbsp;propulsion main engine for the space shuttles demonstrated&amp;nbsp;an ISP of 450 s. However, the target ISP for MEP&amp;nbsp;systems is greater than 1500 s&amp;mdash;enough to transfer a&amp;nbsp;1-kg 10-cm cube from low Earth orbit to interplanetary&amp;nbsp;space with only 200 g of propellant.&lt;/p&gt;