NEXT is one of the projects in the solar electric propulsion technology area.  This project is developing the next generation ion engine technology and is managed by the NASA Glenn Research Center.  NEXT is a propulsion system that could revolutionize the way we send science missions deeper into the solar system.  The thruster uses xenon gas and electrical power to drive future spacecraft. The goal of NEXT program is to develop an ion thruster capable of supporting several key NASA missions in the next decade.  The thruster system will enable NASA to reach destinations in our solar system that cannot be reached by conventional chemical propulsion.

The major feature of NEXT is a thruster that utilized design knowledge gained from the ion thruster that successfully propelled the Deep Space 1 to a flyby of asteroid Braille and the comet Borrelly.  NEXT will have a significant increase in power compared to that of Deep Space 1's ion thruster while increasing efficiency and system performance characteristics.  Advanced power processing, xenon propellant management and thruster gimbal technologies are also being developed by the team to complete the NEXT ion propulsion system

Ion Thrusters
An ion propulsion system's efficient use of fuel and electrical power enable modern spacecraft to travel farther, faster, and cheaper than any other propulsion technology currently available.  Ion thrusters are currently used for stationkeeping on communication satellites and for main propulsion on deep space probes. 

Solar sail propulsion uses the Sun's energy to enable travel through space, much the way wind pushes sailboats across water.  The technology bounces a stream of solar energy particles called photons off giant, reflective sails made of lightweight material 40 to 100 times thinner than a piece of writing paper.  The continuous pressure provides sufficient thrust to perform maneuvers, such as hovering at a point in space and rotating the space vehicle's plane of orbit, which would require too much propellant for conventional rocket systems.  Because the Sun provides the necessary propulsive energy, solar sails also require no onboard propellant, thus reducing payload mass.

NASA's In-Space Propulsion Technologies Program is developing experiments to demonstrate tether-based propulsion - which draws power from the Sun and uses the magnetic field surrounding the Earth to propel spacecraft without the use of on-board propellant.  The innovative technology could dramatically reduce the cost of raising the orbits of other spacecraft, including those destined for deep-space missions.