That's pretty meaningless though, the speed of interest is the heliocentric velocity. Juno was accelerating toward the largest planet in the solar system and or

That's pretty meaningless though, the speed of interest is the heliocentric velocity. Juno was accelerating toward the largest planet in the solar system and orbiting it, not doing a gravitational slingshot. The current record is Voyager 1, which got its speed from a flyby tour of the outer solar system. It is going 17 km/s. https://en.wikipedia.org/wiki/List_of_artificial_objects_leaving_the_Solar_System https://en.wikipedia.org/wiki/List_of_artificial_objects_lea...