QUESTION: I know that the journey to Jupitor took longer expected, What other investigations did it do on its way to jupitor? ANSWER from Dr. Karen Buxbaum on January 4, l996: You are correct that the journey to Jupiter took a long time. If Galileo had launched in 1982 as originally expected, or even in 1984 or 1985 as it might have done, the journey would have taken more like two years. With the 1989 launch, the mission plan had to be redesigned to use a weird, looping trajectory that required just over six years to get us to Jupiter! We used the opportunities that nature and the mission plan provided to us to do many other investigations. I will mention them only briefly here, since there are so many. Many of the results have already been published and can be accessed from your school or public library. Also, our investigators (the Galileo scientists) are making more and more of their findings accessible via the internet. There are Galileo World Wide Web (WWW) pages at JPL and at some of the investigator institutions. You can search for them using key words like Jupiter or Galileo. Back to your question... > Four months after our launch in October, 1989 Galileo flew by Venus. We planned to use all of the orbiter instruments both to see if they were working well and to learn some new stuff about Venus--cloud composition, cloud motions, magneti fields, etc. As we flew by Venus, we accomplished our main goal--the first of three gravity assists that added speed to the spacecraft's motion. In December of 1990 and again in 1992, Galileo flew by the Earth for its second and third gravity assist fly-bys, gaining the necessary speed to finally get the spacecraft on its way to Jupiter! On both of those occasions, we again used the entire payload of orbiter science instruments to study the Earth and the Moon, learning unique things about our own world and refining our knowledge about how to use the instruments to best advantage in the prime mission at Jupiter. A major investigation took place in mid-1991 when Galileo had the first ever spacecraft encounter with an asteroid. We successfully investigated the shape, composition, rotational motion, and magnetic properties of the asteroid Gaspra. Some of the images were returned early, but then all of the data were played back from the on-board tape recorder when we flew near the Earth the second time in December, 1992. In early 1993 we slightly changed the spacecraft flight path so that it would fly by the asteroid Ida in mid 1993. That was the second ever asteroid encounter. The great discovery from the Ida encounter was the asteroid "moon" that we named Dactyl. Dactyl is a small (about 1.5 km across) asteroid that orbits Ida. Some scientists had speculated that there could be such orbiting moons around larger asteroids, but their existence was very controversial before the Galileo discovery of Dactyl! Finally in 1994, the year we didn't plan to have a special big science activity, comet Shoemaker-Levy 9 crashed into Jupiter and Galileo was the ONLY spacecraft that could take pictures of what was happening as the comets crashed. It was hard for us to prepare the observations and command sequences that would acquire the Shoemaker-Levy data because we were swamped with other work and we did not have special funding to do much of the work. (It is exciting but stressful to take advantage of unanticipated opportunities.) Regardless of the difficulties, the results were spectacular and well worth the effort. Lots of scientific journal articles have been written about Galileo results and other observational findings that came from Earth based observatories. All along the way to Jupiter we did what we generally referred to as "cruise science." Our magnetometer took measurements of magnetic fields in interplanetary space. Our dust detector measured dust impacts (very small, high velocity impacts of interplenatary and maybe interstellar dust). Our extreme-ultraviolet spectrometer measured the uneven distribution of certain molecules in space to learn how they were influenced by the solar wind and other physical forces. And our radio science team actually used our spacecraft-to-ground radio signal to study the sun (when Galileo and the Earth were on opposite sides of the sun) and also, at other times, to search for gravity waves. Cruise science provided a long-term, rich source of science data over the years of flight to Jupiter. And that, is the short version of what other investigations we did on the way to Jupiter. If any of this makes you curious, makes you wonder, then hit the library!! Happy New Year, Karen ANSWER from Leslie Tamppari on January 2, 1996: Galileo has been very busy during it's 6 year trip! It took the "scenic route" to Jupiter. This route took us by Venus, back by the Earth and Moon, out to the asteroid belt for a close look at the asteroid Gaspra, back in past the Earth and Moon, back out to the asteroid belt for a close look at Ida and it's satellite Dactyl, and finally on to Jupiter! After we saw Ida and Dactyl, our spacecraft was positioned perfectly, while on it's way to Jupiter, to have a direct view of the big comet, Shoemaker-Levy 9, crash into Jupiter! Each of these was considered an "encounter." During each of these encounters, all 11 instruments aboard our spacecraft were taking as much data and pictures as possible. During the 6 year trip, Galileo did a lot of "firsts." In other words, no one has done that before and so Galileo's data is very important. On the second Earth/Moon encounter, we saw the north pole of the Moon, pretty close up. That was a first. The Gaspra encounter was the first time a spacecraft had ever flown that close to an asteroid! The Ida encounter was only the second time a spacecraft had ever flow that close to an asteroid! And during that flyby, Galileo discovered that Ida had it's own moon! This was a major discovery! That moon was later named Dactyl. And the big comet crash into Jupiter, Shoemaker-Levy 9, was an event that will probably only happen once in our lifetimes. That probably doesn't happen more that once every 1000 years or so! The telescopes from Earth couldn't see the comet's impact site directly; they had to wait for Jupiter to turn enough so they could see it. But, Galileo could see it clearly from where it was in space! That was also a very important event.