NASA has awarded $67 million for a Mars engine

NASA has awarded a $67 million contract to rocket engine manufacturer Aerojet Rocketdyne, in order to create new type of electric propulsion system that could be used for deep space exploration missions. NASA eventually wants to use this type of propulsion on its future Asteroid Redirect Mission, as well as the space agency's ultimate Mars mission plans.
The goal of the 36-month project is to deliver an integrated system that could improve fuel efficiency by a factor of 10 over today’s chemical rocket propulsion systems, and double the thrust capability of current electric propulsion systems, like on the Dawn spacecraft that is now orbiting the dwarf planet Ceres in the asteroid belt.
New propulsion system will use solar panels on a spacecraft that convert sunlight into an electric charge, which is used to excite and accelerate the probe's on-board propellant. This ionized propellant is then driven out the back of the spacecraft, producing thrust that moves the vehicle forward. It's a technique that uses way less fuel than chemical propulsion.

http://www.theverge.com/2016/4/20/1...rocketdyne-solar-electric-propulsion-contract
http://www.geekwire.com/2016/engine...lion-nasa-contract-solar-electric-propulsion/