Pluto is one such planet that has not yet been reached by a space probe.
Never have. It is beyond the sun and we don't have the space techo to get there yet. I don't think there has even in a probe to the planet.
The Mercury Messenger is an orbiting space probe observing the planet Mercury. We generally reserve the word "rover" for a tracked or wheeled vehicle which moves around on the surface, and we haven't tried to do that yet.
to small satelites called pioneer 10 and 11 has explored Pluto
We have no way to know the answer to that question. No human has ever stepped onto another planet, and no space probe has sent back evidence that suggests that life exists on another planet. That's not saying that it doesn't, just that we've never seen evidence of it yet.
Not yet. The New Horizons space probe will fly by Pluto in 2015. It will be the first.
We have not reached Jupiter, yet. That will be the new Space Race
That depends where you are in space. If you are near Earth, maybe Pluto. If you are near Pluto, maybe Mercury.
If I remember correctly from astronomy class it is because the space is to cold for a terrestrial planet to form together, but yet still to warm for a jovial planet.
i think that the first probe was Voyager II in 1977
As of yet, only the Voyager 2 probe has been sent to Neptune. It passed Neptune in 1989.
Simply because it's too far away! Missions to explore space that were launched decades ago still haven't reached the edge of the known solar system yet (i.e. Pluto).
All 8 of the planets in our solar system have been visited by spacecraft, either fly-bys, or actual landings. The dwarf planet pluto has yet to be visited, but a space probe called New Horizons is on its way and should reach Pluto in 2015.