New Horizon was the first spacecraft launched in January 19, 2006. New Horizon's mission is a flyby so it is currently exploring the Kuiper belt. It has taken pictures of the Dwarf planet Pluto and it's 5 moons. It is predicted that New Horizon will leave our Solar System.
Pioneer 10 was launched in March 2, 1972. This was originally supposed to be a flyby pass Jupiter for jupiter for a 21 month mission but Pioneer 10 exceeded this and got to 30 years. Unfortunately, Pioneer sent it's last signal to Earth back in January 2003 and is drifting away.
Pioneer 11 is Pioneer 10's sister spacecraft. It was launched in April 6, 1973. Pioneer carries a message from humanity to the cosmos. Pioneer 11 is the first manmade object to flyby Saturn and capture images of it. The mission ended in 1995.
Voyager 1 was launched back in Sep. 5, 1977. This craft's mission is to explore interstellar space, the space beyond the Kuiper Belt and Outer Solar System. Voyager 1 is still active and alive. Before Voyager 1 left us, it took one last picture of Earth known as, "The Pale Blue Dot." While everybody was celebrating Valentines on Feb. 14, 1990, Voyager 1 was looking down at us one last time.
Voyager 2 was launched Aug. 20, 1977. Voyager 2 is currently the only spacecraft to flyby Uranus and Neptune. This craft was able to discover and learn more about the outer planets, Jupiter, Saturn, Uranus, and Neptune. Such discoveries include the great dark spot on Neptune. Like Voyager 1, it is currently in interestellar space.