I'm wondering what the perihelion of the orbit of Ulysses spacecraft would have been had a trajectory adjustment after its Jupiter swingby not taken place? On Wikipedia it says "The size and shape of the orbit were adjusted to a much smaller degree so that aphelion remained at approximately 5 AU, Jupiter's distance from the Sun, and perihelion was somewhat greater than 1 AU, the Earth's distance from the Sun.", and I've tried to find more elaborate information on this trajectory adjustment, but haven't been able to dig anything up.

I'm asking because I'm running a simulation of Ulysses's trajectory, but it does not take the trajectory adjustment mentioned above into account, and the orbit you end up with has an aphelion at about 5 astronomical units, but the perihelion is well within the orbit of Mercury. So what I'm curious about is whether that would have been Ulysses's trajectory without the post Jupiter swingby burn.

  • $\begingroup$ My apologies fellow community members, but the burn in question was conducted on the 8'th of July 1991 before the Jupiter swingby, and not afterwards. This wasn't altogether clear in the wikipedia article. However, factoring in this burn, I get the correct orbit where the perihelion of Ulysses is just outside of Earth's orbit. $\endgroup$ – Happy Koala Sep 19 '18 at 18:57
  • $\begingroup$ Ah, here's a link for that: jpl.nasa.gov/news/news.php?feature=5674 "The 81/2-minute maneuver began at 6:24 a.m. Pacific Daylight Time. NASA and European Space Agency officials said the maneuver was minor and was designed to alter the spacecraft's trajectory by about 0.29 meters per second (less than one foot per second). " $\endgroup$ – uhoh Sep 20 '18 at 8:18
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    $\begingroup$ Indeed @uhoh! Feel free to turn that into an answer; for whatever reason I'm not entirely comfortable with the idea of answering my own questions, even though I realize that it could be of benefit to the wider community as a quality answer is a quality answer regardless of who did the answering, haha. If anybody is curious about the simulation, feel free to hit me up in the chat and I'll send a link to it once I'm back from work! $\endgroup$ – Happy Koala Sep 20 '18 at 8:31
  • $\begingroup$ Hey, yea, I didn't get a notification, no clue why, but here's a link to the simulator: thehappykoala.github.io/Gravity-Playground It's still a rather buggy affair and very much a work in progress, but feel free to check it out and if you have time provide feedback :)! $\endgroup$ – Happy Koala Sep 21 '18 at 6:35
  • $\begingroup$ And if you click on the credits you'll see that you're mentioned there; an answer you provided a while ago helped me implement the rotating reference frame feature. Let me know if you don't want to be listed, but I like giving credit when it's due! $\endgroup$ – Happy Koala Sep 21 '18 at 6:37

As stated in the comments above, the trajectory adjustment took place on the eighth of July 1991, before Ulysses swung by Jupiter. For more information on its trajectory, please consult:


By changing the start date of the simulation to the first of August 1991, half a year before the Jupiter gravity assist, I was able to simulate the actual orbit of Ulysses. In the image of my simulation below, you will see that Ulysses starts out in an orbit that follows the ecliptic, but once it encounters Jupiter in February 1992, it gets deflected out of the ecliptic into an orbit, which brings it over both the North and South poles of the Sun, with a periohelion just outside Earth's orbit and an aphelion of about five astronomical units.

enter image description here


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