* Astronomy

  Micromachined Propulsion systems for very small satellites

Electric propulsion for spacecraft provides thrust by emitting electrically-charged particles extremely high speeds. Such thrusters do not burn fuel, they eject it. Since the speed of the outgoing particles are much higher for electric propulsion systems than for chemical rockets (high "specific impulse"), much higher efficiency is possible, allowing larger orbit changes with smaller amounts of fuel.
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EPFL - A Couple Drops of Fuel to Get to the Moon with MicroThrust

The first prototype of a new, ultra-compact motor that will allow small satellites to journey beyond Earth's orbit is just making its way out of the EPFL laboratories where it was built. The goal of the micro motor: to drastically reduce the cost of space exploration.