Voyager I mean.

https://news.sky.com/story/nasa-fixes-voyager-1-deep-space-probe-by-firing-thrusters-not-used-in-37-...

It's travelling at aroung 40,000 MPH and in 40 years has "only" gone about 12 billion miles so a lot of work needs to be done before space travel will become a possibility.

40,000 MPH is just too slow. Travelling at the speed of light would take 4½ years to get to the nearest star so that's a bit too slow?

The "trouble" with travelling so fast is that if a bit of space debris got in the way there'd be castrophic damage. We've seen meteors burning up in our atmosphere and most of those are only the size of a grain of sand so imagine hitting a bigger bit?

Most meteors we see burning up are remnants of comets or are from collisions between debris in the Asteroid Belt but some are from out in Space and it's these that might cause a problem in interstellar space travel so I suppose space travellers would need to coin a phrase from Star Trek, "Shields up"?