The Mars Science Laboratory landed on Mars in August 2012. It is a car-sized rover designed to investigate Mas for traces of life/the potential for life in the past.
Pluto will be visited by the spacecraft New Horizon in 2015
Voyager 2 is the only spacecraft to have currently visited both.
All of the eight planets have been visited or orbited by space probes.
The first spacecraft to visit Mercury was Mariner 10 in 1974 -> 1975
April 2008 At present the only planet in our solar system that has not been visited (either by an orbiting spacecraft or flyby spacecraft) has been the recently planet downgraded body of Pluto. There is a mission currently in motion to visit this distant outpost.
No spacecraft has visited all the planets.
Pluto will be visited by the spacecraft New Horizon in 2015
no
voyager 2
Voyager 2 is the only spacecraft to have currently visited both.
yes
Yes
none
Apollo 17
Humans, no. Unmanned spacecraft, yes.
No, only a few unmanned spacecraft have visited Venus. A manned flyby mission was planned by the US in the 1970s following the successful moon landings of the Apollo program, but it was cancelled.
Voyager 2 is the only spacecraft to visited Neptune.