Voyager 1 was launched in September 1977 and is now on the verge of truly entering interstellar space. Expect an announcement any time that this has indeed happened.
The fact that the satellite is still functioning and returning useful scientific data to Earth is a truly magnificent engineering achievement. Indeed there are good grounds for suggesting that the Voyager missions (Voyager 2 is also still functioning) are the most cost effective parts of the whole history of human space exploration.
Maybe it is time to think about building vehicles specifically with the aim of exploring the interstellar medium? Out there we could possibly find out a lot about the galaxy’s physics and that could help with other questions about the nature and formation of the universe.