Object Mission Date First To Achieve
Mercury Mariner 10 March 1974 Fly-by
Venus Mariner 2 December 1962 Fly-by
Venera 4 October 1967 Atmospheric probe
Venera 9 October 1975 Orbiter and surface pictures
Luna Luna 3 October 1959 Pictures from the far side
Luna 9 February 1966 Surface pictures
Luna 10 March 1966 Orbiter
Apollo 11 July 1969 Manned landing
Luna 16 September 1970 Unmanned sample return
Apollo 15 July 1971 Powered vehicle
Mars Mariner 4 July 1965 Fly-by
Mariner 9 November 1971 Orbiter
Mars 2 November 1971 Unmanned landing (capsule lost)
Viking 1 July 1976 Soft landing and surface pictures
Pathfinder July 1997 Powered vehicle
Jupiter Pioneer 10 December 1977 Fly-by
Galileo 7 December 1995 Orbiter & Atmospheric probe
Galileo & Cassini December 2000 Simultaneous study by two spacecraft
Saturn Pioneer 11 September 1979 Fly-by
Cassini July 2004 Orbiter
Titan Huygans January 2005 Atmospheric probe
Uranus Voyager 2 January 1986 Fly-by
Neptune Voyager 2 August 1989 Fly-by

Planetary space missions can be graded in order of difficulty.

  1. Fly-by probe: takes pictures as it moves past
  2. Atmospheric probe: takes readings as it plunges through the atmosphere
  3. Orbiter: braked into orbit by retrorockets and/or aerobraking
  4. Lander: retrorocket, parachute and/or air cusion allows soft landing
  5. Rover: able to move around the surface
  6. Sample return: scoops up soil sample, fires rocket to return to Earth
  7. Manned landing: the ultimate in exploration, but much more expensive

The Moon has been a target for all of these mission types. Mars has reached stage 5 and Venus is at stage 4.
Jupiter and Saturn are at stage 3, Titan is at stage 2, while Uranus and Neptune lag behind at stage 1.