How far will the Voyager 1 actually travel before it stops?

 As of March 2026, Voyager 1 is approximately 23.5 to 24 light-hours away from Earth. The probe is over 24 billion kilometers (15 billion miles) away and is expected to reach the milestone of being one full light-day—24 hours—away from Earth by November 2026. Currently it is in interstellar space, having passed the heliopause.

Voyager 1 uses nuclear batteries that have been qorking since 1977, but will probably exhaust by 2036. Then this probe will be totally useless, disconnected and dead metal.

It will go on traveling. It is very unlikely that it will hit something. It will take tens of thousands of years before it reaches another star system. Now it takes 47 hours to send a command to it and get the feedback or response. If it will fall into the hands of an intelligent alien race after one hundred thousand years, by that time it might be possible human will no longer exist. So sad.

How do scientists measure and track something as far away as Voyager 1 in space?

 Great question!

Since the signals from the two Voyager spacecraft are SO faint at their current distances (e.g., Voyager 1 is an entire light-day from Earth), if we did not have a very good idea where they are, we would be unlikely to ever find them.

As to the instruments used to communicate with them, we rely on the NASA Deep Space Network, supplemented occasionally by the Very Large Array, the Very Long Baseline Array, the European Deep Space Network and the Japanese Deep Space Network.

Here is a rough diagram of the NASA DSN:

and here are pictures of the radiotelescopes at each location:

We are currently in the process of upgrading the dishes at each location: