Which spacecraft is currently headed for interstellar space after flying past several outer planets?

The Voyager spacecraft, specifically Voyager 1 and Voyager 2, are the only probes that have not only traversed the outer planets of our solar system but are also currently headed for interstellar space. Launched in 1977, these spacecraft provided unprecedented data about the gas giants such as Jupiter and Saturn, as well as Uranus and Neptune in Voyager 2’s case.

Voyager 1 famously entered interstellar space in August 2012, followed by Voyager 2 in November 2018, marking significant milestones in human space exploration as these spacecraft continue to send valuable data back to Earth about the heliosphere and the surrounding interstellar medium.

The Pioneer missions, while also significant in their contributions to space exploration, have not traveled beyond the solar system's influence in the same manner as the Voyagers. Similarly, the Lunar Orbiters were focused on mapping the Moon and did not venture into the outer solar system, and the Mariners conducted missions primarily to the inner planets such as Venus and Mars. Therefore, the Voyager missions stand out as the correct answer for this question regarding spacecraft heading towards interstellar space after visiting the outer planets.