Now that we’ve reached the outer solar system, I have to make a decision: Do I cover each planetary system as a unit or do I do an article for each individual “world”? We can exclude all the smaller moons and focus on just the big rounds ones, but even then it would be kind of dumb to have separate articles on say Saturn and Titan since they were co-explored by the same vessels.
It can be argued that the investigation of Jupiter was one of the key ingredients kicking off the Scientific Age, though of course things are always more complicated and messier than that. Nevertheless, Galileo’s observations that there were objects clearly revolving about another body in the sky and not about the Earth ruffled some feathers. Apart obviously from the Sun, Jupiter is the most greatest distinguishing factor of our solar system and yet because of its great distance has been explored a great deal less than the Earth’s sister worlds of Venus and Mars.
Modern Exploration of Jupiter:
- Pioneer 10 (1974) – NASA flyby mission that carried a number of instruments and took the first closeup shots of Jupiter and its moons, though the resolution was fairly low compared to later missions.
- Pioneer 11 (1975) – NASA flyby mission, a twin to Pioneer 10. Investigated the polar regions of Jupiter as it performed a gravitational assist maneuver, and did some further low-resolution shots of the major moons.
- Voyager 1 (1979) – NASA flyby mission that greatly improved on the capabilities of the earlier Pioneer probes (compare this shot of Io from Pioneer 11 with this one from Voyager 1) and the number of images returned was such that animations could be made. Discovered Jupiter’s ring system and Io’s volcanic activity. Ongoing.
- Voyager 2 (1979) – NASA flyby mission, a twin to Voyager 1 that further investigated the Jovian system. Of particular note are the high-resolution images taken of Europe (Voyager 1’s were comparatively low resolution) that strongly hinted of an underground ocean. Ongoing.
- Ulysses (1992) – NASA solar observation mission that used Jupiter as a gravitational assist that made some measurements of Jupiter’s magnetosphere.
- Galileo (1995) – NASA orbiter and atmospheric entry probe mission that studied the Jovian system for 7 years before having a controlled crash into Jupiter’s atmosphere (though the deployment of its high-gain antenna failed so the amount of data returned was not as great as was hoped). Returned a great deal of data about Jupiter and its moons, and included an atmospheric entry component that directly probed the atmosphere. On approach it witnessed the collision of the comet Shoemaker-Levy 9 with Jupiter.
- Cassini (2000) – NASA Saturn mission that used Jupiter as a gravitational assist and returned some of the highest resolution images of Jupiter yet taken as well as information about atmospheric circulation. Ongoing.
- New Horizons (2007) – NASA Pluto mission that used Jupiter as a gravitational assist. Given its more recent construction, the cameras on board were again better than previous missions and returned a fair amount of data on the Jovian system (of certain interest, an animation of an eruption on Io). Ongoing.
- Juno (2016?) – NASA orbiter mission current on approach to Jupiter to be placed in a polar orbit and will be only the second orbiter in that system (the third overall for the outer solar system after Galileo and Cassini). Interestingly, because of advances in solar technology Juno will rely on solar panels to power its nine instruments unlike previous missions which required nuclear-based RTGs. Ongoing.
- Jupiter Icy Moon Explorer (202x?) – Proposed ESA mission focusing on Ganymede.
- Io Volcanic Observer (202x?) – Proposed NASA mission focusing on Io.