The US does actually have some other significant firsts in space, especially in the outer solar system:
- First probe to reach Jupiter (Pioneer 10)
- First probe to reach escape velocity needed to leave the solar system (Pioneer 10)
- Arguably, first probe to leave the solar system (Pioneer 10 or Voyager 1, depending on the definition of "leave the solar system")
- First probe to orbit Jupiter (Galileo)
- First probe to fly-by an asteroid (Galileo) -- passed by 951 Gaspra
- First probe to reach Saturn (Pioneer 11)
- First (and only) probe to visit Uranus (Voyager 2)
- First (and only) probe to visit Neptune (Voyager 2)
- First (and only) probe to visit Pluto (New Horizons)
- First probe to reach Mercury (Mariner 10)
- First probe to orbit Mercury (MESSENGER) -- also, to date, these are the only two probes to visit Mercury
- First probe to orbit two different celestial bodies (Dawn) -- it orbited the asteroids Vesta and Ceres. Also, the first time either body has been visited by a probe.
- First photograph of Earth from orbit (Explorer 6) -- not a particularly good image by modern standards, but a pretty significant first given the importance spy satellites have played in international relations since then (You can see the image here: https://en.wikipedia.org/wiki/File:First_satellite_photo_-_E... )
Somewhat less significant by modern standards, but still interesting:
- First probe to send back data from Venus (Mariner 2) -- the USSR had a fly-by before this (Venera 1), but lost contact with the probe and so couldn't get any data from the fly-by, unfortunately. Mariner 2 didn't have a camera though.
- First probe to successfully return images from Mars (Mariner 4) -- the USSR had the first fly-by (Mars 1), a few years earlier but they lost contact with the probe before it actually reached Mars.
- First probe to orbit Mars (Mariner 9) -- also the first to orbit another planet. Only just barely beat the USSR Mars 2 probe by about two weeks though.
- First probe to reach Jupiter (Pioneer 10)
- First probe to reach escape velocity needed to leave the solar system (Pioneer 10)
- Arguably, first probe to leave the solar system (Pioneer 10 or Voyager 1, depending on the definition of "leave the solar system")
- First probe to orbit Jupiter (Galileo)
- First probe to fly-by an asteroid (Galileo) -- passed by 951 Gaspra
- First probe to reach Saturn (Pioneer 11)
- First (and only) probe to visit Uranus (Voyager 2)
- First (and only) probe to visit Neptune (Voyager 2)
- First (and only) probe to visit Pluto (New Horizons)
- First probe to reach Mercury (Mariner 10)
- First probe to orbit Mercury (MESSENGER) -- also, to date, these are the only two probes to visit Mercury
- First probe to orbit two different celestial bodies (Dawn) -- it orbited the asteroids Vesta and Ceres. Also, the first time either body has been visited by a probe.
- First photograph of Earth from orbit (Explorer 6) -- not a particularly good image by modern standards, but a pretty significant first given the importance spy satellites have played in international relations since then (You can see the image here: https://en.wikipedia.org/wiki/File:First_satellite_photo_-_E... )
Somewhat less significant by modern standards, but still interesting:
- First probe to send back data from Venus (Mariner 2) -- the USSR had a fly-by before this (Venera 1), but lost contact with the probe and so couldn't get any data from the fly-by, unfortunately. Mariner 2 didn't have a camera though.
- First probe to successfully return images from Mars (Mariner 4) -- the USSR had the first fly-by (Mars 1), a few years earlier but they lost contact with the probe before it actually reached Mars.
- First probe to orbit Mars (Mariner 9) -- also the first to orbit another planet. Only just barely beat the USSR Mars 2 probe by about two weeks though.
Some other interesting links on space history:
- https://en.wikipedia.org/wiki/Timeline_of_space_exploration
- https://en.wikipedia.org/wiki/List_of_Solar_System_probes