1. Voyager 1: Launched in 1977, it was the first spacecraft to reach interstellar space, confirmed in 2013.
2. Voyager 2: Also launched in 1977, it followed Voyager 1 into interstellar space, confirmed in 2018.
3. New Horizons: Launched in 2006, it flew by Pluto in 2015 and is now exploring the Kuiper Belt. While not yet in interstellar space, it is expected to cross the heliopause in the 2040s.
4. Pioneer 10: Launched in 1972, it was the first spacecraft to fly past Jupiter and is now considered to be in interstellar space, though confirmation is lacking due to its lack of communication.
5. Pioneer 11: Launched in 1973, it is also believed to be in interstellar space, but confirmation is lacking.
So, while "Voyager 1" is the first confirmed to be in interstellar space, there are several others that have potentially crossed the heliopause.
