All of the NASA missions traveling through the solar system are far-ranging robots. In addition to the missions highlighted below, check out others at Missions.
Mars Science Laboratory Curiosity Rover
The Mars Science Laboratory Curiosity Rover is studying Mars' habitability, carrying the biggest, most advanced suite of instruments for scientific studies ever sent to the Martian surface. It has relied on new technological innovations, especially for landing. The spacecraft descended on a parachute and then, during the final seconds prior to landing, lowered the upright rover on a tether to the surface, much like a sky crane. On the surface, the rover is be able to roll over obstacles up to 75 cm high and travel up to 90 m per hour.
As a mission belonging to NASA's Discovery Program, Dawn is responsible for driving new technology innovation. The Dawn spacecraft uses ion propulsion to get the additional velocity needed to reach Vesta, to spiral to lower altitudes on Vesta, to leave Vesta and cruise to Ceres and to spiral to a low altitude orbit at Ceres. Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity ten times that of chemical rockets.
The systems for this spacecraft were designed to address the challenges of becoming the first mission to orbit Mercury, in the high radiation environment so close to the sun. MESSENGER is tough, with a sunshade and other protection to withstand searing sunlight and roasting heat bouncing back from the planet below, and lightweight, since most of its mass was fuel used to slow the spacecraft down enough to be captured by Mercury's gravity.
Juno will avoid Jupiter's highest radiation regions by approaching over the north, dropping to an altitude below the planet's radiation belts - which are analogous to Earth's Van Allen belts, but far more deadly - and then exiting over the south. To protect sensitive spacecraft electronics, Juno will carry the first radiation shielded electronics vault, a critical feature for enabling sustained exploration in such a heavy radiation environment.